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Title:
INHIBITORS OF CD73-MEDIATED IMMUNOSUPPRESSION
Document Type and Number:
WIPO Patent Application WO/2018/094148
Kind Code:
A1
Abstract:
Compounds that modulate the conversion of AMP to adenosine by 5'- nucleotidase, ecto, and compositions containing the compounds and methods for synthesizing the compounds, are described herein. The use of such compounds and compositions for the treatment and/or prevention of a diverse array of diseases, disorders and conditions, including cancer- and immune-related disorders, that are mediated by 5'- nucleotidase, ecto is also provided.

Inventors:
KALISIAK JAROSLAW (US)
LAWSON KENNETH (US)
LELETI MANMOHAN (US)
LINDSEY ERICK (US)
MILES DILLON (US)
NEWCOMB ERIC (US)
POWERS JAY (US)
SHARIF EHESAN (US)
Application Number:
US2017/062166
Publication Date:
May 24, 2018
Filing Date:
November 17, 2017
Export Citation:
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Assignee:
ARCUS BIOSCIENCES INC (US)
International Classes:
A61K31/70; C07H19/16
Domestic Patent References:
WO1994017803A11994-08-18
WO2017120508A12017-07-13
Foreign References:
US5700786A1997-12-23
US6713623B22004-03-30
US5646128A1997-07-08
Attorney, Agent or Firm:
KEZER, William, B. et al. (US)
Download PDF:
Claims:
WHAT IS CLAIMED IS: 1. A compound having the formula:

or a pharmaceutically acceptable salt, hydrate, or solvate thereof, wherein,

Rla and Rlb are independently selected from the group consisting of hydrogen, optionally

substituted Ci-C6 alkyl, optionally substituted aryl, optionally substituted -C(R2aR2b)- aryl, -C(R2aR2b)-0-C(0)-OR3, -C(R2aR2b)-0-C(0)R3 , and -C(R2a R2b)C(0)OR3;

optionally, Rla and Rlb groups are combined to form a 5- to 6-membered heterocyclic ring;

each R2a and R2b is independently selected from the group consisting of H and optionally

substituted Ci-C6 alkyl;

each R3 is independently selected from the group consisting of H, Ci-C6 alkyl, C1-C4 alkoxy(Ci- C4)alkyl and optionally substituted aryl;

R5a and R5b are independently selected from the group consisting of H, optionally substituted Ci- C6 alkyl, -C(0)OR3, C3-C6 cycloalkyl(Ci-C6)alkyl, aryl(Ci-C6)alkyl, C3-C6 cycloalkyl and aryl;

each X is independently selected from the group consisting of O, H, and S;

A is selected from the group consisting of:

each of which is optionally substituted with from 1 to 5 R6 substituents, and wherein the subscript n is an integer from 0 to 3;

Z is selected from the group consisting of NH, NR6, and O; each R6 is independently selected from the group consisting of CH3, ORg, CN, F, and optionally substituted Ci-C6 alkyl; or two R6 groups on adjacent ring vertices are optionally joined together to form a 5- to 6-membered ring having at least one heteroatom as a ring vertex; and

Het is select from the group consisting of:

wherein the wavy line indicates the point of attachment to the remainder of the compound, wherein each G, when present, is independently selected from the group consisting of N and CRe, and wherein: Ra is selected from the group consisting of H, H2, HR , HC(0)R7a, R aR , R7a, OH, SR7a and OR7a;

Rb is selected from the group consisting of H, halogen, H2, HR7a, R7aR7b, R7a, OH, and OR7a;

Rc and Rd are independently selected from the group consisting of H, halogen, haloalkyl, H2,

HR7a, R7aR7b, R7a, OH, OR7a, SR7a,

S02R7a, -X^NHz, -X^ HR73, -X^ R^R713, -X^OH, -X^OR73, -X^SR73

and -X^SOzR73;

each Re is independently selected from the group consisting of H, halogen, and optionally

substituted Ci-C6 alkyl;

each Rg is independently selected from the group consisting of H and -C(0)-Ci-C6 alkyl;

each X1 is Ci-C4alkylene; and

each R7a and R7b is independently selected from the group consisting of optionally substituted Ci-Cio alkyl, optionally substituted C2-Cio alkenyl, optionally substituted C2-Cio alkynyl, optionally substituted C3-C7 cycloalkyl, optionally substituted C3-C7 cycloalkylCi- C4alkyl, optionally substituted 4-7 membered cycloheteroalkyl, optionally substituted 4-7 membered cycloheteroalkylCi-C4alkyl, optionally substituted aryl, optionally substituted arylCi-C4alkyl, optionally substituted arylC2-C4alkenyl, optionally substituted arylC2- C4alkynyl, optionally substituted heteroaryl, optionally substituted heteroarylCi-C4alkyl, optionally substituted heteroarylCi-C4alkenyl, and optionally substituted heteroarylC2- C4alkynyl; or R7a and R7b when attached to the same nitrogen atom are optionally joined together to form a 4- to 7-membered heterocyclic ring, optionally fused to an aryl ring. 2. A compound of claim 1, wherein A is:

which is optionally substituted with from 1 to 5 R6.

A compound of claim 2, wherein A is selected from the group consisting

A compound of claim 1, wherein Het

5. A compound of claim 4, wherein Rc is other than hydrogen.

6. A compound of claim 5, having a formula selected from the group consisting of:

7. A compound of claim 6, wherein each X is oxygen.

8. A compound of claim 7, wherein Re is hydrogen.

9. A compound of claim 8, wherein each Rg is hydrogen.

10. A compound of claim 1, wherein R5a is selected from the group consisting of H, optionally substituted Ci-4alkyl, -C(0)OR3, C3-C6 cycloalkyl(Ci-C4)alkyl and aryl(Ci- C4)alkyl, and R5b is H.

11. A compound of claim 1, wherein R a is selected from the group consisting of H, optionally substituted Ci-4alkyl, -C(0)OR3, C3-C6 cycloalkyl(Ci-C4)alkyl and aryl(Ci- C4)alkyl, R5b is H, and each X is O. 12. A compound of claim 1, wherein R5a is selected from the group consisting of H, optionally substituted Ci-4alkyl, -C(0)OR3, C3-C6 cycloalkyl(Ci-C4)alkyl and aryl(Ci- C4)alkyl, R5b is H, each X is O, and Rla and Rlb are H.

13 A compound of claim 1, wherein Het is selected from

14. A compound of claim 13, wherein R a is selected from the group consisting of optionally substituted Ci-3alkyl, -C(0)OH, C3-C6 cycloalkyl(Ci-C2)alkyl and phenyl(Ci-C2)alkyl, R5b is H, each X is O, and Rla and Rlb are H. 15. A compound of claim 13, wherein R5a is selected from the group consisting of optionally substituted Ci-3alkyl, -C(0)OH, C3-C6 cycloalkyl(Ci-C2)alkyl and phenyl(Ci-C2)alkyl, R5b is H, each X is O, Rla and Rlb are H, Re is H, and Ra is selected from the group consi sting of NH2, HR7a and R7aR7b . 16. A compound of claim 13, wherein R5a is selected from the group consisting of optionally substituted Ci-3alkyl, -C(0)OH, C3-C6 cycloalkyl(Ci-C2)alkyl and phenyl(Ci-C2)alkyl, R5b is H, each X is O, Rla and Rlb are H, Re is H, Rc is other than H, and Ra is HR7a. 17. A compound of claim 16, wherein R7a is selected from the group consisting of optionally substituted C3-C7 cycloalkyl, optionally substituted C3-C7 cycloalkylCi- C4alkyl, optionally substituted 4-7 membered cycloheteroalkyl, and optionally substituted 4-7 membered cycloheteroalkylCi-C4alkyl.

18. A compound of claim 17, wherein R is C3-C7 cycloalkyl, or 4-7 membered cycloheteroalkylCi-C4alkyl.

19. A compound of claim 18, wherein R7a is cyclopentyl.

20. A compound of claim 6, having the formula:

21. A compound of claim 20, wherein R and R are H; each X is O; Rg is H; and Rc is CI.

22. A compound of claim 6, having the formula:

23. A compound of claim 22, wherein R and R are H; each X is O; Rg is H; and Rc is CI.

24. A compound of claim 20, having the formula:

A compound of claim 22, having the formula:

A compound of claim 6, having the formula:

27. A compound of claim 26, wherein Rla and R are H; each X is O; Rg is H; and Rc is CI. 28. A compound of claim 6, having the formula:

29. A compound of claim 28, wherein R and R are H; each X is O; Rg is H; and Rc is CI. 30. A compound of claim 26, having the formula:

A compound of claim 28, having the formula:

32. A compound of claim 1, selected from the compounds of Table 1. 33. A pharmaceutical composition comprising a compound of any one of claims 1 to 32, and a pharmaceutically acceptable excipient. 34. A method of treating a disease, disorder, or condition, mediated at least in part by CD73, said method comprising administering an effective amount of a compound of any one of claims 1 to 32, to a subject in need thereof. 35. A method of claim 34, wherein said compound is administered in an amount effective to reverse or stop the progression of CD73 -mediated immunosuppression. 36 A method of claim 34, wherein said disease, disorder, or condition is cancer.

37. A method of claim 36, wherein said cancer is a cancer of the prostate, colon, rectum, pancreas, cervix, stomach, endometrium, brain, liver, bladder, ovary, testis, head, neck, skin (including melanoma and basal carcinoma), mesothelial lining, white blood cell (including lymphoma and leukemia), esophagus, breast, muscle, connective tissue, lung

(including small-cell lung carcinoma and non-small-cell carcinoma), adrenal gland, thyroid, kidney, or bone; or is glioblastoma, mesothelioma, renal cell carcinoma, gastric carcinoma, sarcoma (including Kaposi's sarcoma), choriocarcinoma, cutaneous basocellular carcinoma, or testicular seminoma. 38. A method of claim 36, wherein said cancer is selected from the group consisting of melanoma, colon cancer, pancreatic cancer, breast cancer, prostate cancer, lung cancer, leukemia, a brain tumor, lymphoma, ovarian cancer, and Kaposi's sarcoma. 39. A method of claim 34, wherein said disease, disorder, or condition is an immune-related disease, disorder or condition selected from the group consisting of rheumatoid arthritis, kidney failure, lupus, asthma, psoriasis, colitis, pancreatitis, allergies, fibrosis, anemia fibromyalgia, Alzheimer's disease, congestive heart failure, stroke, aortic valve stenosis, arteriosclerosis, osteoporosis, Parkinson's disease, infections, Crohn's disease, ulcerative colitis, allergic contact dermatitis and other eczemas, systemic sclerosis and multiple sclerosis. 40. A combination comprising a compound of claim 1 to 32, and at least one additional therapeutic agent. 41. A combination of claim 40, wherein the at least one additional therapeutic agent is a chemotherapeutic agent, an immune- and/or inflammation-modulating agent, an anti- hypercholesterolemia agent, or an anti-infective agent. 42. A combination of claim 40, wherein the at least one additional therapeutic agent is an immune checkpoint inhibitor.

43. A kit comprising a compound of any one of claims 1 to 32, and at least one additional therapeutic agent. 44. A kit of claim 43, wherein the at least one additional therapeutic agent is a chemotherapeutic agent, an immune- and/or inflammation-modulating agent, an anti- hypercholesterolemia agent, or an anti-infective agent. 45. A kit of claim 43, wherein the at least one additional therapeutic agent is an immune checkpoint inhibitor. 46. A method of treating cancer in a subject, said method comprising administering to said subject an effective amount of a compound of any one of claims 1 to 32 and an immune checkpoint inhibitor. 47. A method in accordance with claim 46, wherein said administering is prior to, concurrent with, or subsequent to, radiation treatment. 48. A method in accordance with claim 46, wherein said compound and said immune checkpoint inhibitor are administered in combination. 49. A method in accordance with claim 46, wherein said compound and said immune checkpoint inhibitor are administered sequentially. 50. A method in accordance with claim 46, wherein said compound is administered after said immune checkpoint inhibitor. 51. A method in accordance with claim 46, wherein said compound is administered prior to said immune checkpoint inhibitor. 52. A combination, kit or method of any one of 42, 45, 46, wherein said immune checkpoint inhibitor is selected from the group consisting of ipulimumab, nivolumab and lambrolizumab.

53. A method of treating cancer in a subject, said method comprising administering to said subject an effective amount of a compound of any one of claims 1 to 32.

54. A method of claim 53, wherein said cancer is a cancer of the prostate, colon, rectum, pancreas, cervix, stomach, endometrium, brain, liver, bladder, ovary, testis, head, neck, skin (including melanoma and basal carcinoma), mesothelial lining, white blood cell (including lymphoma and leukemia), esophagus, breast, muscle, connective tissue, lung

(including small-cell lung carcinoma and non-small-cell carcinoma), adrenal gland, thyroid, kidney, or bone; or is glioblastoma, mesothelioma, renal cell carcinoma, gastric carcinoma, sarcoma (including Kaposi's sarcoma), choriocarcinoma, cutaneous basocellular carcinoma, or testicular seminoma. 55. A method of claim 53, wherein said cancer is selected from the group consisting of melanoma, colon cancer, pancreatic cancer, breast cancer, prostate cancer, lung cancer, leukemia, a brain tumor, lymphoma, ovarian cancer, and Kaposi's sarcoma. 56. A method in accordance with claim 53, wherein said administering is prior to, concurrent with, or subsequent to, radiation treatment.

Description:
INHIBITORS OF CD73-MEDIATED IMMUNOSUPPRESSION

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Application Ser. No. 62/424,241, filed November 18, 2016, the entire content of which is incorporated herein by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

[0002] NOT APPLICABLE

REFERENCE TO A "SEQUENCE LISTING," A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISK

[0003] NOT APPLICABLE

BACKGROUND OF THE INVENTION

[0004] Purinergic signaling, a type of extracellular signaling mediated by purine nucleotides and nucleosides such as ATP and adenosine, involves the activation of purinergic receptors in the cell and/or in nearby cells, resulting in the regulation of cellular functions. Most cells have the ability to release nucleotides, which generally occurs via regulated exocytosis (see

Praetorius, H. A.; Leipziger, J. (1 March 2010) Ann Rev Physiology 72(1): 377-393). The released nucleotides can then be hydrolyzed extracellularly by a variety of cellular membrane- bound enzymes referred to as ectonucleotidases.

[0005] Ectonucleotides catalyze the conversion of ATP to adenosine, an endogenous modulator that impacts multiple systems, including the immune system, the cardiovascular system, the central nervous system, and the respiratory system. Adenosine also promotes fibrosis in a variety of tissues. In the first step of the production of adenosine, ectonucleoside triphosphate diphosphohydrolase 1 (ENTPDl), also known as CD39 (Cluster of Differentiation 39), hydrolyzes ATP to ADP, and then ADP to AMP. In the next step, AMP is converted to adenosine by 5'-nucleotidase, ecto (NT5E or 5NT), also known as CD73 (Cluster of Differentiation 73).

[0006] The enzymatic activities of CD39 and CD73 play strategic roles in calibrating the duration, magnitude, and chemical nature of purinergic signals delivered to various cells (e.g., immune cells). Alteration of these enzymatic activities can change the course or dictate the outcome of several pathophysiological events, including cancer, autoimmune diseases, infections, atherosclerosis, and ischemia-reperfusion injury, suggesting that these ecto-enzymes represent novel therapeutic targets for managing a variety of disorders.

[0007] CD73 inhibition with monoclonal antibodies, siRNA, or small molecules delays tumor growth and metastasis (Stagg, J. (2010) PNAS U.S.A.107: 1547-52). For example, anti-CD73 antibody therapy was shown to inhibit breast tumor growth and metastasis in animal models (Stagg, J. (26 Jan 2010) PNAS U.S.A, 107(4): 1547-52). In addition, the use of antibodies that specifically bind CD73 has been evaluated for the treatment of bleeding disorders (e.g., hemophilia) (U.S. Patent No. 9,090,697). Recently, there have been several efforts to develop therapeutically useful CD73 small molecule inhibitors. For example, Bhattarai et al. ((2015) J Med Chem 58:6248-63) have studied derivatives and analogs of α,β-Methylene-ADP (AOPCP), one of the most metabolically stable, potent and selective CD73 inhibitors known, and purine CD73 derivatives have been reported in the patent literature (WO 2015/164573). However, the development of small molecules has been hampered due to, for example, less than ideal metabolic stability.

[0008] In view of the role played by CD73 in cancer, as well as a diverse array of other diseases, disorders and conditions, and the current lack of CD73 inhibitors available to medical practitioners, new CD73 inhibitors, and compositions and methods associated therewith, are needed. BRIEF SUMMARY OF THE INVENTION

[0009] The present invention relates to compounds that modulate the conversion of AMP to adenosine by 5'-nucleotidase, ecto (NT5E or 5NT; also known as CD73), and compositions (e.g., pharmaceutical compositions) comprising the compounds. Such compounds, including methods of their synthesis, and compositions are described in detail below.

[0010] The present invention also relates to the use of such compounds and compositions for the treatment and/or prevention of a diverse array of diseases, disorders and conditions mediated, in whole or in part, by CD73. C 73 inhibitors have been linked to the treatment of a diverse array of disorders, including cancer, fibrosis, neurological and neurodegenerative disorders (e.g., depression and Parkinson's disease), cerebral and cardiac ischemic diseases, immune-related disorders, and disorders with an inflammatory component. [See, e.g., Sorrentino et al (2013) Oncolmmunol, 2:e22448, doi: 10.4161/onci.22448; and Regateiro et al. (2012) Clin. Exp.

Immunol, 171 : 1-7]. In particular embodiments, the compounds described herein act to inhibit the immunosuppressive activity and/or the anti-inflammatory activity of CD73, and are useful as therapeutic or prophylactic therapy when such inhibition is desired. Unless otherwise indicated, when uses of the compounds of the present invention are described herein, it is to be understood that such compounds may be in the form of a composition (e.g., a pharmaceutical composition). [0011] As used herein, the terms "CD73 inhibitor", "CD73 blocker", "adenosine by 5'- nucleotidase, ecto inhibitor", "NT5E inhibitor", "5NT inhibitor" and all other related art- accepted terms refer to a compound capable of modulating, either directly or indirectly, the CD73 receptor in an in vitro assay, an in vivo model, and/or other means indicative of therapeutic efficacy. The terms also refer to compounds that exhibit at least some therapeutic benefit in a human subject.

[0012] Although the compounds of the present invention are believed to effect their activity by inhibition of CD73, a precise understanding of the compounds' underlying mechanism of action is not required to practice the invention. For example, the compounds can also effect their activity, at least in part, through modulation (e.g., inhibition) of other components of the purinergic signaling pathway (e.g., CD39). The purinergic signaling system consists of transporters, enzymes and receptors responsible for the synthesis, release, action, and

extracellular inactivation of (primarily) ATP and its extracellular breakdown product adenosine (Sperlagh, B. et al. (Dec 2012) Neuropsychopharmacologia Hungarica 14(4):231-38). Because inhibition of CD73 results in decreased adenosine, CD73 inhibitors can be used for the treatment of diseases or disorders mediated by adenosine and its actions on adenosine receptors, including Al, A 2 A, A 2B and A3, [see Yegutkin, GG (May 2008) Biochimica Biophysica Acta 1783(5):673- 94].

[0013] For purposes of the present disclosure, the purinergic signaling process can be described as comprising the following components. The purinergic receptors (PI, P2X and P2Y), a first component, are membrane receptors that mediate various physiological functions (e.g., relaxation of gut smooth muscle) as a response to the release of ATP or adenosine; in general, all cells have the ability to release nucleotides into the extracellular environment, frequently through regulated exocytosis. The nucleoside transporters (NTs), a second component, are membrane transport proteins which transport nucleoside substrates (e.g., adenosine) across cell membranes; the extracellular concentration of adenosine can be regulated by NTs, possibly in the form of a feedback loop connecting receptor signaling with transporter function. As previously described, the ectonucleotidases (CD73 and CD39) hydrolyze nucleotides released into the extracellular environment and comprise a further component.

Another component of the purinergic signaling process comprises the pannexins; in particular, the pannexin-1 channel (PANXl) is an integral component of the P2X/P2Y purinergic signaling pathway and the key contributor to pathophysiological ATP release.

[0014] In one particular aspect, the present invention provides compounds having Formula

R la and R lb are independently selected from the group consisting of hydrogen, optionally

substituted Ci-C 6 alkyl, optionally substituted aryl, optionally substituted -C(R 2a R 2b )- aryl, -C(R 2a R 2b )-0-C(0)-OR 3 , -C(R 2a R 2b )-0-C(0)R 3 , and -C(R 2a R 2b )C(0)OR 3 ;

optionally, R la and R lb groups are combined to form a 5- to 6-membered heterocyclic ring;

each R 2a and R 2b is independently selected from the group consisting of H and optionally

substituted Ci-C 6 alkyl; each R 3 is independently selected from the group consisting of H, Ci-C 6 alkyl, C1-C4 alkoxy(Ci-

C 4 )alkyl and optionally substituted aryl;

R 5a and R 5b are independently selected from the group consisting of H, optionally substituted Ci-

C 6 alkyl, -C(0)OR 3 , C 3 -C 6 cycloalkyl(Ci-C 6 )alkyl aryl(Ci-C 6 )alkyl, C 3 -C 6 cycloalkyl and aryl;

each X is selected from the group consisting of O, H, and S;

A is selected from the group consisting of:

each of which is optionally substituted with from 1 to 5 R 6 substituents, and wherein the subscript n is an integer from 0 to 3;

Z is selected from the group consisting of NH, NR 6 , and O;

each R 6 is independently selected from the group consisting of CH 3 , OR g , CN, F, and

optionally substituted Ci-C 6 alkyl; or two R 6 groups on adjacent ring vertices are optionally joined together to form a 5- to 6-membered ring having at least one heteroatom as a ring vertex; and

Het is selected from the group consisting of:

wherein the wavy line indicates the point of attachment to the remainder of the compound, wherein each G, when present, is independently selected from the group consisting of N and CR e , and wherein:

R a is selected from the group consisting of H, H 2 , HR 7a , HC(0)R 7a , R 7a R 7b , R 7a , OH, SR 7: and OR 7a ;

R b is selected from the group consisting of H, halogen, H 2 , HR 7a , R 7a R 7b , R 7a , OH, and OR 7a ; R c and R d are independently selected from the group consisting of H, halogen, haloalkyl, H 2 , HR 7a , R 7a R 7b , R 7a , OH, OR 7a , SR 7a ,

S0 2 R 7a , -X^NHz, -X^ HR 73 , -X^ R^R 713 , -X^OH, -X^OR 73 , -X^SR 73

and -X^SOzR 73 ;

each R e is independently selected from the group consisting of H, halogen, and optionally

substituted Ci-C 6 alkyl;

each R g is independently selected from the group consisting of H and -C(0)-Ci-C 6 alkyl;

each X 1 is Ci-C4alkylene; and

each R 7a and R 7b is independently selected from the group consisting of optionally substituted Ci-Cio alkyl, optionally substituted C 2 -Cio alkenyl, optionally substituted C 2 -Cio alkynyl, optionally substituted C3-C7 cycloalkyl, optionally substituted C3-C7 cycloalkylCi- C 4 alkyl, optionally substituted 4-7 membered cycloheteroalkyl, optionally substituted 4-7 membered cycloheteroalkylCi-C 4 alkyl, optionally substituted aryl, optionally substituted arylCi-C 4 alkyl, optionally substituted arylC 2 -C 4 alkenyl, optionally substituted arylC 2 - C 4 alkynyl, optionally substituted heteroaryl, optionally substituted heteroarylCi-C 4 alkyl, optionally substituted heteroarylCi-C 4 alkenyl, and optionally substituted heteroarylC 2 - C 4 alkynyl; or R 7a and R 7b when attached to the same nitrogen atom are optionally joined together to form a 4- to 7-membered heterocyclic ring, optionally fused to an aryl ring.

[0015] In some embodiments, the present invention contemplates methods for treating or preventing cancer in a subject (e.g., a human) comprising administering to the subject a therapeutically effective amount of at least one CD73 inhibitor described herein. The present invention includes methods of treating or preventing a cancer in a subject by administering to the subject a CD73 inhibitor in an amount effective to reverse or stop the progression of CD73- mediated immunosuppression. In some embodiments, the CD73 -mediated immunosuppression is mediated by an antigen-presenting cell (APC).

[0016] Examples of the cancers that can be treated using the compounds and compositions described herein include, but are not limited to: cancers of the prostate, colorectum, pancreas, cervix, stomach, endometrium, brain, liver, bladder, ovary, testis, head, neck, skin (including melanoma and basal carcinoma), mesothelial lining, white blood cell (including lymphoma and leukemia) esophagus, breast, muscle, connective tissue, lung (including small-cell lung carcinoma and non-small-cell carcinoma), adrenal gland, thyroid, kidney, or bone; glioblastoma, mesothelioma, renal cell carcinoma, gastric carcinoma, sarcoma, choriocarcinoma, cutaneous basocellular carcinoma, and testicular seminoma. In some embodiments of the present invention, the cancer is melanoma, colon cancer, pancreatic cancer, breast cancer, prostate cancer, lung cancer, leukemia, a brain tumor, lymphoma, sarcoma, ovarian cancer, or Kaposi's sarcoma. Cancers that are candidates for treatment with the compounds and compositions of the present invention are discussed further hereafter.

[0017] The present invention contemplates methods of treating a subject receiving a bone marrow transplant or peripheral blood stem cell transplant by administering a therapeutically effective amount of an CD73 inhibitor sufficient to increase the delayed-type hypersensitivity reaction to tumor antigen, delay the time-to-relapse of post-transplant malignancy, increase relapse-free survival time post-transplant, and/or increase long-term post-transplant survival.

[0018] In certain embodiments, the present invention contemplates methods for treating or preventing an infective disorder (e.g., a viral infection) in a subject (e.g., a human) comprising administering to the subject a therapeutically effective amount of at least one CD73 inhibitor (e.g., a novel inhibitor of the instant invention). In some embodiments, the infective disorder is a viral infection (e.g., a chronic viral infection), a bacterial infection, a fungal infection, or a parasitic infection. In certain embodiments, the viral infection is human immunodeficiency virus or cytomegalovirus.

[0019] In still other embodiments, the present invention contemplates methods for treating and/or preventing immune-related diseases, disorders and conditions; diseases having an inflammatory component; as well as disorders associated with the foregoing; with at least one CD73 inhibitor of the instant invention. Examples of immune-related diseases, disorders and conditions are described hereafter.

[0020] Other diseases, disorders and conditions that can be treated or prevented, in whole or in part, by modulation of CD73 activity are candidate indications for the CD73 inhibitor compounds of the present invention. [0021] The present invention further contemplates the use of the CD73 inhibitors described herein in combination with one or more additional agents. The one or more additional agents may have some CD73 -modulating activity and/or they may function through distinct

mechanisms of action. In some embodiments, such agents comprise radiation (e.g., localized radiation therapy or total body radiation therapy) and/or other treatment modalities of a non- pharmacological nature. When combination therapy is utilized, the CD73 inhibitor(s) and the one additional agent(s) may be in the form of a single composition or multiple compositions, and the treatment modalities can be administered concurrently, sequentially, or through some other regimen. By way of example, the present invention contemplates a treatment regimen wherein a radiation phase is followed by a chemotherapeutic phase. The combination therapy can have an additive or synergistic effect. Other benefits of combination therapy are described hereafter.

[0022] In some embodiments, the present invention further comprises the use of the CD73 inhibitors described herein in combination with bone marrow transplantation, peripheral blood stem cell transplantation, or other types of transplantation therapy. [0023] In particular embodiments, the present invention contemplates the use of the inhibitors of CD73 function described herein in combination with immune checkpoint inhibitors. The blockade of immune checkpoints, which results in the amplification of antigen-specific T cell responses, has been shown to be a promising approach in human cancer therapeutics. Examples of immune checkpoints (ligands and receptors), some of which are selectively upregulated in various types of tumor cells, that are candidates for blockade include PD1 (programmed cell death protein 1); PDL1 (PD1 ligand); BTLA (B and T lymphocyte attenuator); CTLA4

(cytotoxic T-lymphocyte associated antigen 4); TIM3 (T-cell membrane protein 3); LAG3 (lymphocyte activation gene 3); A2aR (adenosine A2a receptor A2aR); and Killer Inhibitory Receptors. Immune checkpoint inhibitors, and combination therapy therewith, are discussed in detail elsewhere herein.

[0024] In other embodiments, the present invention provides methods for treating cancer in a subject, comprising administering to the subject a therapeutically effective amount of at least one CD73 inhibitor and at least one chemotherapeutic agent, such agents including, but not limited to alkylating agents (e.g., nitrogen mustards such as chlorambucil, cyclophosphamide, isofamide, mechlorethamine, melphalan, and uracil mustard; aziridines such as thiotepa; methanesulphonate esters such as busulfan; nucleoside analogs (e.g., gemcitabine); nitroso ureas such as carmustine, lomustine, and streptozocin; topoisomerase 1 inhibitors (e.g., irinotecan); platinum complexes such as cisplatin and carboplatin; bioreductive alkylators such as mitomycin, procarbazine, dacarbazine and altretamine); DNA strand-breakage agents (e.g., bleomycin); topoisomerase II inhibitors (e.g., amsacrine, dactinomycin, daunorubicin, idarubicin, mitoxantrone, doxorubicin, etoposide, and teniposide); DNA minor groove binding agents (e.g., plicamydin); antimetabolites (e.g., folate antagonists such as methotrexate and trimetrexate; pyrimidine antagonists such as fluorouracil, fluorodeoxyuridine, CB3717, azacitidine, cytarabine, and floxuridine; purine antagonists such as mercaptopurine, 6-thioguanine, fludarabine, pentostatin; asparginase; and ribonucleotide reductase inhibitors such as hydroxyurea); tubulin interactive agents (e.g., vincristine, estramustine, vinblastine, docetaxol, epothilone derivatives, and paclitaxel);

hormonal agents (e.g., estrogens; conjugated estrogens; ethinyl estradiol; diethylstilbesterol; chlortrianisen; idenestrol; progestins such as hydroxyprogesterone caproate,

medroxyprogesterone, and megestrol; and androgens such as testosterone, testosterone propionate, fluoxymesterone, and methyltestosterone); adrenal corticosteroids (e.g., prednisone, dexamethasone, methylprednisolone, and prednisolone); leutinizing hormone releasing agents or gonadotropin-releasing hormone antagonists (e.g., leuprolide acetate and goserelin acetate); and antihormonal antigens (e.g., tamoxifen, antiandrogen agents such as flutamide; and antiadrenal agents such as mitotane and aminoglutethimide). The present invention also contemplates the use of the CD73 inhibitors in combination with other agents known in the art (e.g., arsenic trioxide) and other chemotherapeutic agents that may be developed in the future.

[0025] In some embodiments drawn to methods of treating cancer, the administration of a therapeutically effective amount of an CD73 inhibitor in combination with at least one chemotherapeutic agent results in a cancer survival rate greater than the cancer survival rate observed by administering either agent alone. In further embodiments drawn to methods of treating cancer, the administration of a therapeutically effective amount of an CD73 inhibitor in combination with at least one chemotherapeutic agent results in a reduction of tumor size or a slowing of tumor growth greater than reduction of the tumor size or tumor growth observed by administration of either agent alone. [0026] In further embodiments, the present invention contemplates methods for treating or preventing cancer in a subject, comprising administering to the subject a therapeutically effective amount of at least one CD73 inhibitor and at least one signal transduction inhibitor (STI). In a particular embodiment, the at least one STI is selected from the group consisting of bcr/abl kinase inhibitors, epidermal growth factor (EGF) receptor inhibitors, her-2/neu receptor inhibitors, and farnesyl transferase inhibitors (FTIs). Other candidate STI agents are set forth elsewhere herein.

[0027] The present invention also contemplates methods of augmenting the rejection of tumor cells in a subject comprising administering an CD73 inhibitor in conjunction with at least one chemotherapeutic agent and/or radiation therapy, wherein the resulting rejection of tumor cells is greater than that obtained by administering either the CD73 inhibitor, the chemotherapeutic agent or the radiation therapy alone.

[0028] In further embodiments, the present invention provides methods for treating cancer in a subject, comprising administering to the subject a therapeutically effective amount of at least one CD73 inhibitor and at least one immunomodulator other than an CD73 inhibitor.

[0029] The present invention contemplates embodiments comprising methods for treating or preventing an infective disorder (e.g., a viral infection) in a subject (e.g., a human) comprising administering to the subject a therapeutically effective amount of at least one CD73 inhibitor and a therapeutically effective amount of an anti -infective agent(s), such as one or more

antimicrobial agents.

[0030] In additional embodiments, treatment of an infective disorder is effected through the co-administration of a vaccine in combination with administration of a therapeutically effective amount of an CD73 inhibitor of the present invention. In some embodiments, the vaccine is an anti-viral vaccine, including, for example, an anti-HIV vaccine. In other embodiments, the vaccine is effective against tuberculosis or malaria. In still other embodiments, the vaccine is a tumor vaccine (e.g., a vaccine effective against melanoma); the tumor vaccine can comprise genetically modified tumor cells or a genetically modified cell line, including genetically modified tumor cells or a genetically modified cell line that has been transfected to express granulocyte-macrophage stimulating factor (GM-CSF). In particular embodiments, the vaccine includes one or more immunogenic peptides and/or dendritic cells.

[0031] In certain embodiments drawn to treatment of an infection by administering an CD73 inhibitor and at least one additional therapeutic agent, a symptom of infection observed after administering both the CD73 inhibitor and the additional therapeutic agent is improved over the same symptom of infection observed after administering either alone. In some embodiments, the symptom of infection observed can be reduction in viral load, increase in CD4 + T cell count, decrease in opportunistic infections, increased survival time, eradication of chronic infection, or a combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 depicts a simplified representation of extracellular purinergic signaling.

DETAILED DESCRIPTION OF THE INVENTION

[0033] Before the present invention is further described, it is to be understood that the invention is not limited to the particular embodiments set forth herein, and it is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0034] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. [0035] It must be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology such as "solely," "only" and the like in connection with the recitation of claim elements, or use of a "negative" limitation.

[0036] The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed.

General

[0037] The number of subjects diagnosed with cancer and the number of deaths attributable to cancer continue to rise. Traditional treatment approaches comprising chemotherapy and radiotherapy are generally difficult for the patient to tolerate and become less effective as cancers (e.g., tumors) evolve to circumvent such treatments. Recent experimental evidence indicates that CD73 inhibitors may represent an important new treatment modality for cancer (e.g., breast cancer) treatment.

[0038] Promising data also support the role of inhibitors of CD73 function to inhibit the antiinflammatory activity of CD73 and/or the immunosuppressive activity of CD73, and thus CD73 inhibitors may be useful to treat, for example, immunosuppressive diseases (e.g., HIV and AIDs). Inhibition of CD73 may also be an important treatment strategy for patients with neurological or neuropsychiatric diseases or disorders such as depression.

[0039] The present invention is drawn to, inter alia, small molecule compounds having CD73 inhibitory activity, as well as compositions thereof, and methods of using the compounds and compositions for the treatment and prevention of the diseases, disorders and conditions described herein. Definitions

[0040] Unless otherwise indicated, the following terms are intended to have the meaning set forth below. Other terms are defined elsewhere throughout the specification.

[0041] The term "alkyl", by itself or as part of another substituent, means, unless otherwise stated, a straight or branched chain hydrocarbon radical, having the number of carbon atoms designated (i.e. Ci- 8 means one to eight carbons). Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, n-pentyl, n-hexyl, n-heptyl, n- octyl, and the like.

[0042] The term "cycloalkyl" refers to hydrocarbon rings having the indicated number of ring atoms (e.g., C3-6 cycloalkyl) and being fully saturated or having no more than one double bond between ring vertices. "Cycloalkyl" is also meant to refer to bicyclic and polycyclic hydrocarbon rings such as, for example, bicyclo[2.2.1]heptane, bicyclo[2.2.2]octane, etc.

[0043] The term "cycloheteroalkyl" refers to a cycloalkyl ring having the indicated number of ring vertices (or members) and having from one to five heteroatoms selected from N, O, and S, which replace one to five of the carbon vertices, and wherein the nitrogen and sulfur atoms are optionally oxidized, and the nitrogen atom(s) are optionally quaternized. The cycloheteroalkyl may be a monocyclic, a bicyclic or a polycylic ring system. Non limiting examples of cycloheteroalkyl groups include pyrrolidine, imidazolidine, pyrazolidine, butyrolactam, valerolactam, imidazolidinone, hydantoin, dioxolane, phthalimide, piperidine, 1,4-dioxane, morpholine, thiomorpholine, thiomorpholine-S-oxide, thiomorpholine-S,S-oxide, piperazine, pyran, pyridone, 3-pyrroline, thiopyran, pyrone, tetrahydrofuran, tetrhydrothiophene, quinuclidine, and the like. A cycloheteroalkyl group can be attached to the remainder of the molecule through a ring carbon or a heteroatom.

[0044] As used herein, a wavy line, that intersects a single, double or triple bond in any chemical structure depicted herein, represent the point attachment of the single, double, or triple bond to the remainder of the molecule. Additionally, a bond extending to the center of a ring (e.g., a phenyl ring) is meant to indicate attachment at any of the available ring vertices. One of skill in the art will understand that multiple substituents shown as being attached to a ring will occupy ring vertices that provide stable compounds and are otherwise sterically compatible. For a divalent component, a representation is meant to include either orientation (forward or reverse). For example, the group "-C(0) H-" is meant to include a linkage in either

orientation: -C(0) H- or - HC(O)-, and similarly, "-O-CH2CH2-" is meant to include both -O-CH2CH2- and -CH2CH2-O-.

[0045] The terms "alkoxy," "alkylamino" and "alkylthio" (or thioalkoxy) are used in their conventional sense, and refer to those alkyl groups attached to the remainder of the molecule via an oxygen atom, an amino group, or a sulfur atom, respectively. Additionally, for dialkylamino groups, the alkyl portions can be the same or different and can also be combined to form a 3-7 membered ring with the nitrogen atom to which each is attached.

Accordingly, a group represented as dialkylamino or -NR a R b is meant to include piperidinyl, pyrrolidinyl, morpholinyl, azetidinyl and the like.

[0046] The terms "arylalkyl" and "heteroarylalkyl" are used in their conventional sense, and refer to those groups wherein an aryl group or a heteroaryl group is attached remainder of the molecule via C1-C4 alkylene linker. An exemplary embodiment of "arylalkyl" is phenylmethyl (or benzyl). Similarly, an exemplary embodiment of "heteroarylalkyl" is, for example, 3- pyridylpropyl. When Optionally substituted' is used to describe either of the terms "arylalkyl" or "heteroarylalkyl", it is meant to refer to those groups wherein the aryl or heteroaryl portion is optionally substituted as in the definitions below, and the alkyl portion is optionally substituted as in the definitions below

[0047] The terms "halo" or "halogen," by themselves or as part of another substituent, mean, unless otherwise stated, a fluorine, chlorine, bromine, or iodine atom. Additionally, terms such as "haloalkyl," are meant to include monohaloalkyl and polyhaloalkyl. For example, the term "C1-4 haloalkyl" is mean to include trifluoromethyl, 2,2,2-trifluoroethyl, 4- chlorobutyl, 3-bromopropyl, and the like.

[0048] The term "aryl" means, unless otherwise stated, a polyunsaturated, typically aromatic, hydrocarbon group which can be a single ring or multiple rings (up to three rings) which are fused together or linked covalently. Non-limiting examples of aryl groups include phenyl, naphthyl and biphenyl.

[0049] The term "heteroaryl" refers to aryl groups (or rings) that contain from one to five heteroatoms selected from N, O, and S, wherein the nitrogen and sulfur atoms are optionally oxidized, and the nitrogen atom(s) are optionally quaternized. A heteroaryl group can be attached to the remainder of the molecule through a heteroatom. Non-limiting examples of heteroaryl groups include pyridyl, pyridazinyl, pyrazinyl, pyrimindinyl, triazinyl, quinolinyl, quinoxalinyl, quinazolinyl, cinnolinyl, phthalazinyl, benzotriazinyl, purinyl, benzimidazolyl, benzopyrazolyl, benzotriazolyl, benzisoxazolyl, isobenzofuryl, isoindolyl, indolizinyl, benzotriazinyl, thienopyridinyl, thienopyrimidinyl, pyrazolopyrimidinyl, imidazopyri dines, benzothiaxolyl, benzofuranyl, benzothienyl, indolyl, quinolyl, isoquinolyl, isothiazolyl, pyrazolyl, indazolyl, pteridinyl, imidazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiadiazolyl, pyrrolyl, thiazolyl, furyl, thienyl and the like. Substituents for a heteroaryl ring can be selected from the group of acceptable substituents described below. [0050] The above terms (e.g., "alkyl," "aryl" and "heteroaryl"), in some embodiments, will be optionally substituted. Selected substituents for each type of radical are provided below.

[0051] Optional substituents for the alkyl radicals (including those groups often referred to as alkylene, alkenyl, alkynyl and cycloalkyl) can be a variety of groups selected from:

halogen, -OR', -NR'R", -SR\ -SiR'R"R"', -OC(O)R\ -C(O)R\ -CO 2 R\ -CONR'R", -OC(O)NR'R", -NR"C(O)R\ -NR'-C(O)NR"R"\ -NR"C(O) 2 R\ -NH-C(NH 2 )=NH,

-NR'C(NH 2 )=NH, -NH-C(NH 2 )=NR', -S(O)R', -S(O) 2 R', -S(O) 2 NR'R", -NR'S(O) 2 R", -CN and -NO 2 in a number ranging from zero to (2 m'+l), where m' is the total number of carbon atoms in such radical. R', R" and R'" each independently refer to hydrogen, unsubstituted Ci-8 alkyl, unsubstituted aryl, aryl substituted with 1 -3 halogens, unsubstituted Ci- 8 alkyl, Ci- 8 alkoxy or Ci- 8 thioalkoxy groups, or unsubstituted aryl-Ci-4 alkyl groups. When R' and R" are attached to the same nitrogen atom, they can be combined with the nitrogen atom to form a 3-, 4-, 5-, 6-, or 7-membered ring. For example, -NR'R" is meant to include 1-pyrrolidinyl and 4-morpholinyl. [0052] Similarly, optional substituents for the aryl and heteroaryl groups are varied and are generally selected from: -halogen, -OR', -OC(O)R', -NR'R", -SR', -R', -CN, -NO2, - CO2R', -CONR'R", -C(O)R', -OC(O)NR'R", -NR"C(O)R', -NR"C(O) 2 R', -NR'- C(O)NR"R"', -NH-C(NH 2 )=NH, -NR'C(NH 2 )=NH, -NH-C(NH 2 )=NR', -S(O)R', - S(O) 2 R', -S(O) 2 NR'R", -NR'S(O) 2 R", -N 3 , perfluoro(Ci-C 4 )alkoxy, and perfluoro(Ci-

C 4 )alkyl, in a number ranging from zero to the total number of open valences on the aromatic ring system; and where R', R" and R'" are independently selected from hydrogen, Ci -8 alkyl, Ci -8 haloalkyl, C 3-6 cycloalkyl, C 2-8 alkenyl and C 2-8 alkynyl. Other suitable substituents include each of the above aryl substituents attached to a ring atom by an alkylene tether of from 1-4 carbon atoms.

[0053] Two of the substituents on adjacent atoms of the aryl or heteroaryl ring may optionally be replaced with a substituent of the formula -T-C(O)-(CH 2 ) q -U-, wherein T and U are independently -NH-, -O-, -CH 2 - or a single bond, and q is an integer of from 0 to 2.

Alternatively, two of the substituents on adjacent atoms of the aryl or heteroaryl ring may optionally be replaced with a substituent of the formula -A-(CH 2 ) r -B-, wherein A and B are independently -CH 2 -, -O-, -NH-, -S-, -S(O)-, -S(O) 2 -, -S(O) 2 NR'- or a single bond, and r is an integer of from 1 to 3. One of the single bonds of the new ring so formed may optionally be replaced with a double bond. Alternatively, two of the substituents on adjacent atoms of the aryl or heteroaryl ring may optionally be replaced with a substituent of the formula - (CH 2 ) s -X-(CH 2 )t-, where s and t are independently integers of from 0 to 3, and X is -O-, - NR'-, -S-, -S(O)-, -S(O) 2 -, or -S(O) 2 NR'-. The substituent R' in -NR'- and -S(O) 2 NR'- is selected from hydrogen or unsubstituted Ci- 6 alkyl.

[0054] As used herein, the term "heteroatom" is meant to include oxygen (O), nitrogen (N), sulfur (S) and silicon (Si). [0055] The term "pharmaceutically acceptable salts" is meant to include salts of the active compounds which are prepared with relatively nontoxic acids or bases, depending on the particular substituents found on the compounds described herein. When compounds of the present invention contain relatively acidic functionalities, base addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of the desired base, either neat or in a suitable inert solvent. Examples of salts derived from pharmaceutically- acceptable inorganic bases include aluminum, ammonium, calcium, copper, ferric, ferrous, lithium, magnesium, manganic, manganous, potassium, sodium, zinc and the like. Salts derived from pharmaceutically-acceptable organic bases include salts of primary, secondary and tertiary amines, including substituted amines, cyclic amines, naturally-occuring amines and the like, such as arginine, betaine, caffeine, choline, Ν,Ν'-dibenzylethylenediamine, diethylamine, 2- diethylaminoethanol, 2-dimethylaminoethanol, ethanolamine, ethylenediamine, N- ethylmorpholine, N-ethylpiperidine, glucamine, glucosamine, histidine, hydrabamine, isopropylamine, lysine, methyl glucamine, morpholine, piperazine, piperidine, polyamine resins, procaine, purines, theobromine, triethylamine, trimethylamine, tripropylamine, tromethamine and the like. When compounds of the present invention contain relatively basic functionalities, acid addition salts can be obtained by contacting the neutral form of such compounds with a sufficient amount of the desired acid, either neat or in a suitable inert solvent. Examples of pharmaceutically acceptable acid addition salts include those derived from inorganic acids like hydrochloric, hydrobromic, nitric, carbonic, monohydrogencarbonic, phosphoric,

monohydrogenphosphoric, dihydrogenphosphoric, sulfuric, monohydrogensulfuric, hydriodic, or phosphorous acids and the like, as well as the salts derived from relatively nontoxic organic acids like acetic, propionic, isobutyric, malonic, benzoic, succinic, suberic, fumaric, mandelic, phthalic, benzenesulfonic, p-tolyl sulfonic, citric, tartaric, methanesulfonic, and the like. Also included are salts of amino acids such as arginate and the like, and salts of organic acids like glucuronic or galactunoric acids and the like (see, for example, Berge, S.M., et al,

"Pharmaceutical Salts", Journal of Pharmaceutical Science, 1977, 66, 1-19). Certain specific compounds of the present invention contain both basic and acidic functionalities that allow the compounds to be converted into either base or acid addition salts.

[0056] The neutral forms of the compounds may be regenerated by contacting the salt with a base or acid and isolating the parent compound in the conventional manner. The parent form of the compound differs from the various salt forms in certain physical properties, such as solubility in polar solvents, but otherwise the salts are equivalent to the parent form of the compound for the purposes of the present invention. [0057] In addition to salt forms, the present invention provides compounds which are in a prodrug form. Prodrugs of the compounds described herein are those compounds that readily undergo chemical changes under physiological conditions to provide the compounds of the present invention. Additionally, prodrugs can be converted to the compounds of the present invention by chemical or biochemical methods in an ex vivo environment. For example, prodrugs can be slowly converted to the compounds of the present invention when placed in a transdermal patch reservoir with a suitable enzyme or chemical reagent.

[0058] Certain compounds of the present invention can exist in unsolvated forms as well as solvated forms, including hydrated forms. In general, the solvated forms are equivalent to unsolvated forms and are intended to be encompassed within the scope of the present invention. Certain compounds of the present invention may exist in multiple crystalline or amorphous forms. In general, all physical forms are equivalent for the uses contemplated by the present invention and are intended to be within the scope of the present invention.

[0059] Certain compounds of the present invention possess asymmetric carbon atoms (optical centers) or double bonds; the racemates, diastereomers, geometric isomers, regioisomers and individual isomers (e.g., separate enantiomers) are all intended to be encompassed within the scope of the present invention. When a stereochemical depiction is shown, it is meant to refer the compound in which one of the isomers is present and substantially free of the other isomer. 'Substantially free of another isomer indicates at least an 80/20 ratio of the two isomers, more preferably 90/10, or 95/5 or more. In some embodiments, one of the isomers will be present in an amount of at least 99%.

[0060] The compounds of the present invention may also contain unnatural proportions of atomic isotopes at one or more of the atoms that constitute such compounds. Unnatural proportions of an isotope may be defined as ranging from the amount found in nature to an amount consisting of 100% of the atom in question. For example, the compounds may incorporate radioactive isotopes, such as for example tritium ( 3 H), iodine-125 ( 125 I) or carbon-14 ( 14 C), or non-radioactive isotopes, such as deuterium ( 2 H) or carbon-13 ( 13 C). Such isotopic variations can provide additional utilities to those described elsewhere within this application. For instance, isotopic variants of the compounds of the invention may find additional utility, including but not limited to, as diagnostic and/or imaging reagents, or as cytotoxic/radiotoxic therapeutic agents. Additionally, isotopic variants of the compounds of the invention can have altered pharmacokinetic and pharmacodynamic characteristics which can contribute to enhanced safety, tolerability or efficacy during treatment. All isotopic variations of the compounds of the present invention, whether radioactive or not, are intended to be encompassed within the scope of the present invention.

[0061] The terms "patient" or "subject" are used interchangeably to refer to a human or a non- human animal (e.g., a mammal).

[0062] The terms "administration", "administer" and the like, as they apply to, for example, a subject, cell, tissue, organ, or biological fluid, refer to contact of, for example, an inhibitor of CD73, a pharmaceutical composition comprising same, or a diagnostic agent to the subject, cell, tissue, organ, or biological fluid. In the context of a cell, administration includes contact (e.g., in vitro or ex vivo) of a reagent to the cell, as well as contact of a reagent to a fluid, where the fluid is in contact with the cell. [0063] The terms "treat", "treating", treatment" and the like refer to a course of action (such as administering an inhibitor of CD73 or a pharmaceutical composition comprising same) initiated after a disease, disorder or condition, or a symptom thereof, has been diagnosed, observed, and the like so as to eliminate, reduce, suppress, mitigate, or ameliorate, either temporarily or permanently, at least one of the underlying causes of a disease, disorder, or condition afflicting a subject, or at least one of the symptoms associated with a disease, disorder, condition afflicting a subject. Thus, treatment includes inhibiting (e.g., arresting the development or further development of the disease, disorder or condition or clinical symptoms association therewith) an active disease.

[0064] The term "in need of treatment" as used herein refers to a judgment made by a physician or other caregiver that a subject requires or will benefit from treatment. This judgment is made based on a variety of factors that are in the realm of the physician's or caregiver's expertise. [0065] The terms "prevent", "preventing", "prevention" and the like refer to a course of action (such as administering an CD73 inhibitor or a pharmaceutical composition comprising same) initiated in a manner (e.g., prior to the onset of a disease, disorder, condition or symptom thereof) so as to prevent, suppress, inhibit or reduce, either temporarily or permanently, a subject's risk of developing a disease, disorder, condition or the like (as determined by, for example, the absence of clinical symptoms) or delaying the onset thereof, generally in the context of a subject predisposed to having a particular disease, disorder or condition. In certain instances, the terms also refer to slowing the progression of the disease, disorder or condition or inhibiting progression thereof to a harmful or otherwise undesired state. [0066] The term "in need of prevention" as used herein refers to a judgment made by a physician or other caregiver that a subject requires or will benefit from preventative care. This judgment is made based on a variety of factors that are in the realm of a physician's or caregiver's expertise.

[0067] The phrase "therapeutically effective amount" refers to the administration of an agent to a subject, either alone or as part of a pharmaceutical composition and either in a single dose or as part of a series of doses, in an amount capable of having any detectable, positive effect on any symptom, aspect, or characteristic of a disease, disorder or condition when administered to the subject. The therapeutically effective amount can be ascertained by measuring relevant physiological effects, and it can be adjusted in connection with the dosing regimen and diagnostic analysis of the subject's condition, and the like. By way of example, measurement of the serum level of an CD73 inhibitor (or, e.g., a metabolite thereof) at a particular time post- administration may be indicative of whether a therapeutically effective amount has been used.

[0068] The phrase "in a sufficient amount to effect a change" means that there is a detectable difference between a level of an indicator measured before (e.g., a baseline level) and after administration of a particular therapy. Indicators include any objective parameter (e.g., serum concentration) or subjective parameter (e.g., a subject's feeling of well-being).

[0069] The term "small molecules" refers to chemical compounds having a molecular weight that is less than about lOkDa, less than about 2kDa, or less than about lkDa. Small molecules include, but are not limited to, inorganic molecules, organic molecules, organic molecules containing an inorganic component, molecules comprising a radioactive atom, and synthetic molecules. Therapeutically, a small molecule may be more permeable to cells, less susceptible to degradation, and less likely to elicit an immune response than large molecules. [0070] The term "ligand" refers to, for example, a peptide, a polypeptide, a membrane- associated or membrane-bound molecule, or a complex thereof, that can act as an agonist or antagonist of a receptor. A ligand encompasses natural and synthetic ligands, e.g., cytokines, cytokine variants, analogs, muteins, and binding compositions derived from antibodies, as well as small molecules. The term also encompasses an agent that is neither an agonist nor antagonist, but that can bind to a receptor without significantly influencing its biological properties, e.g., signaling or adhesion. Moreover, the term includes a membrane-bound ligand that has been changed by, e.g., chemical or recombinant methods, to a soluble version of the membrane-bound ligand. A ligand or receptor may be entirely intracellular, that is, it may reside in the cytosol, nucleus, or some other intracellular compartment. The complex of a ligand and receptor is termed a "ligand-receptor complex."

[0071] The terms "inhibitors" and "antagonists", or "activators" and "agonists" refer to inhibitory or activating molecules, respectively, for example, for the activation of, e.g., a ligand, receptor, cofactor, gene, cell, tissue, or organ. Inhibitors are molecules that decrease, block, prevent, delay activation, inactivate, desensitize, or down-regulate, e.g., a gene, protein, ligand, receptor, or cell. Activators are molecules that increase, activate, facilitate, enhance activation, sensitize, or up-regulate, e.g., a gene, protein, ligand, receptor, or cell. An inhibitor may also be defined as a molecule that reduces, blocks, or inactivates a constitutive activity. An "agonist" is a molecule that interacts with a target to cause or promote an increase in the activation of the target. An "antagonist" is a molecule that opposes the action(s) of an agonist. An antagonist prevents, reduces, inhibits, or neutralizes the activity of an agonist, and an antagonist can also prevent, inhibit, or reduce constitutive activity of a target, e.g., a target receptor, even where there is no identified agonist.

[0072] The terms "modulate", "modulation" and the like refer to the ability of a molecule (e.g., an activator or an inhibitor) to increase or decrease the function or activity of CD73, either directly or indirectly. A modulator may act alone, or it may use a cofactor, e.g., a protein, metal ion, or small molecule. Examples of modulators include small molecule compounds and other bioorganic molecules. Numerous libraries of small molecule compounds (e.g., combinatorial libraries) are commercially available and can serve as a starting point for identifying a modulator. The skilled artisan is able to develop one or more assays (e.g., biochemical or cell- based assays) in which such compound libraries can be screened in order to identify one or more compounds having the desired properties; thereafter, the skilled medicinal chemist is able to optimize such one or more compounds by, for example, synthesizing and evaluating analogs and derivatives thereof. Synthetic and/or molecular modeling studies can also be utilized in the identification of an Activator.

[0073] The "activity" of a molecule may describe or refer to the binding of the molecule to a ligand or to a receptor; to catalytic activity; to the ability to stimulate gene expression or cell signaling, differentiation, or maturation; to antigenic activity; to the modulation of activities of other molecules; and the like. The term "proliferative activity" encompasses an activity that promotes, that is necessary for, or that is specifically associated with, for example, normal cell division, as well as cancer, tumors, dysplasia, cell transformation, metastasis, and angiogenesis.

[0074] As used herein, "comparable", "comparable activity", "activity comparable to", "comparable effect", "effect comparable to", and the like are relative terms that can be viewed quantitatively and/or qualitatively. The meaning of the terms is frequently dependent on the context in which they are used. By way of example, two agents that both activate a receptor can be viewed as having a comparable effect from a qualitative perspective, but the two agents can be viewed as lacking a comparable effect from a quantitative perspective if one agent is only able to achieve 20% of the activity of the other agent as determined in an art-accepted assay (e.g., a dose-response assay) or in an art-accepted animal model. When comparing one result to another result (e.g., one result to a reference standard), "comparable" frequently (though not always) means that one result deviates from a reference standard by less than 35%, by less than 30%, by less than 25%, by less than 20%, by less than 15%, by less than 10%, by less than 7%, by less than 5%), by less than 4%, by less than 3%, by less than 2%, or by less than 1%. In particular embodiments, one result is comparable to a reference standard if it deviates by less than 15%, by less than 10%, or by less than 5% from the reference standard. By way of example, but not limitation, the activity or effect may refer to efficacy, stability, solubility, or immunogenicity.

[0075] "Substantially pure" indicates that a component makes up greater than about 50% of the total content of the composition, and typically greater than about 60% of the total polypeptide content. More typically, "substantially pure" refers to compositions in which at least 75%, at least 85%), at least 90% or more of the total composition is the component of interest. In some cases, the polypeptide will make up greater than about 90%, or greater than about 95% of the total content of the composition.

[0076] The terms "specifically binds" or "selectively binds", when referring to a

ligand/receptor, antibody/antigen, or other binding pair, indicates a binding reaction which is determinative of the presence of the protein in a heterogeneous population of proteins and other biologies. Thus, under designated conditions, a specified ligand binds to a particular receptor and does not bind in a significant amount to other proteins present in the sample. The antibody, or binding composition derived from the antigen-binding site of an antibody, of the contemplated method binds to its antigen, or a variant or mutein thereof, with an affinity that is at least twofold greater, at least ten times greater, at least 20-times greater, or at least 100-times greater than the affinity with any other antibody, or binding composition derived therefrom. In a particular embodiment, the antibody will have an affinity that is greater than about 10 9 liters/mol, as determined by, e.g., Scatchard analysis (Munsen, et al. 1980 Analyt. Biochem. 107:220-239). [0077] The term "response," for example, of a cell, tissue, organ, or organism, encompasses a change in biochemical or physiological behavior, e.g., concentration, density, adhesion, or migration within a biological compartment, rate of gene expression, or state of differentiation, where the change is correlated with activation, stimulation, or treatment, or with internal mechanisms such as genetic programming. In certain contexts, the terms "activation",

"stimulation", and the like refer to cell activation as regulated by internal mechanisms, as well as by external or environmental factors; whereas the terms "inhibition", "down-regulation" and the like refer to the opposite effects. [0078] The terms "polypeptide," "peptide," and "protein", used interchangeably herein, refer to a polymeric form of amino acids of any length, which can include genetically coded and non- genetically coded amino acids, chemically or biochemically modified or derivatized amino acids, and polypeptides having modified polypeptide backbones. The terms include fusion proteins, including, but not limited to, fusion proteins with a heterologous amino acid sequence, fusion proteins with heterologous and homologous leader sequences, with or without N-terminus methionine residues; immunologically tagged proteins; and the like.

[0079] As used herein, the terms "variants" and "homologs" are used interchangeably to refer to amino acid or DNA sequences that are similar to reference amino acid or nucleic acid sequences, respectively. The term encompasses naturally-occurring variants and non-naturally- occurring variants. Naturally-occurring variants include homologs (polypeptides and nucleic acids that differ in amino acid or nucleotide sequence, respectively, from one species to another), and allelic variants (polypeptides and nucleic acids that differ in amino acid or nucleotide sequence, respectively, from one individual to another within a species). Thus, variants and homologs encompass naturally occurring DNA sequences and proteins encoded thereby and their isoforms, as well as splice variants of a protein or gene. The terms also encompass nucleic acid sequences that vary in one or more bases from a naturally-occurring DNA sequence but still translate into an amino acid sequence that corresponds to the naturally-occurring protein due to degeneracy of the genetic code. Non-naturally-occurring variants and homologs include polypeptides and nucleic acids that comprise a change in amino acid or nucleotide sequence, respectively, where the change in sequence is artificially introduced (e.g., muteins); for example, the change is generated in the laboratory by human intervention ("hand of man"). Therefore, non-naturally occurring variants and homologs may also refer to those that differ from the naturally-occurring sequences by one or more conservative substitutions and/or tags and/or conjugates.

[0080] The term "muteins" as used herein refers broadly to mutated recombinant proteins. These proteins usually carry single or multiple amino acid substitutions and are frequently derived from cloned genes that have been subjected to site-directed or random mutagenesis, or from completely synthetic genes. [0081] The terms "DNA", "nucleic acid", "nucleic acid molecule", "polynucleotide" and the like are used interchangeably herein to refer to a polymeric form of nucleotides of any length, either deoxyribonucleotides or ribonucleotides, or analogs thereof. Non-limiting examples of polynucleotides include linear and circular nucleic acids, messenger RNA (mRNA),

complementary DNA (cDNA), recombinant polynucleotides, vectors, probes, primers and the like.

5'-Nucleotidase, ecto and Inhibition Thereof

[0082] Human CD73 (also referred to as 5 '-nucleotidase, ecto; NT5E; or 5NT) is a 574 amino acid residue protein (Accession No. AAH6593). Eukaryotic CD73 functions as a noncovalent homodimer with two structural domains, wherein the N- and C-terminal domains are connected by a hinge region that enables the enzyme to undergo large domain movements and switch between open and closed conformations (Knapp, K. et al. (2012) Structure 20:2161-73).

[0083] As used herein, the terms "CD73 inhibitor", "CD73 blocker", "adenosine by 5'- nucleotidase, ecto inhibitor", "NT5E inhibitor", "5NT inhibitor" and all other related art- accepted terms refer to a compound capable of modulating, either directly or indirectly, the CD73 receptor in an in vitro assay, an in vivo model, and/or other means indicative of therapeutic efficacy. The terms also refer to compounds that exhibit at least some therapeutic benefit in a human subject. An CD73 inhibitor may be a competitive, noncompetitive, or irreversible CD73 inhibitor. "A competitive CD73 inhibitor" is a compound that reversibly inhibits CD73 enzyme activity at the catalytic site; "a noncompetitive CD73 inhibitor" is a compound that reversibly inhibits CD73 enzyme activity at a non-catalytic site; and "an irreversible CD73 inhibitor" is a compound that irreversibly eliminates CD73 enzyme activity by forming a covalent bond (or other stable means of inhibiting enzyme function) with the enzyme. [0084] CD73 inhibitors can modulate purinergic signaling, a type of extracellular signaling mediated by purine nucleotides and nucleosides such as ATP and adenosine. Purinergic signaling involves the activation of purinergic receptors in the cell and/or in nearby cells, resulting in the regulation of cellular functions. The enzymatic activity of CD73 plays a strategic role in calibrating the duration, magnitude, and chemical nature of purinergic signals delivered to various cells (e.g., immune cells). Alteration of these enzymatic activities can change the course or dictate the outcome of several pathophysiological events, including cancer, autoimmune and inflammatory diseases, infections, atherosclerosis, and ischemia-reperfusion injury, suggesting that these ecto-enzymes represent novel therapeutic targets for managing a variety of disorders.

[0085] Studies using tissues that overexpress CD73 and using CD73 knock-out mice have provided evidence that CD73 inhibitors have potential utility for melanomas, lung cancer, prostate cancer, and breast cancer (see, e.g., Sadej R. (2006) Melanoma Res 16:213-22).

Because higher expression levels of CD73 are associated with tumor neovascularization, invasiveness, resistance to chemotherapy, and metastasis, CD73 inhibitors can be used to control tumor progression and metastasis. Other potential utilities are discussed elsewhere herein.

[0086] As set forth above, although the compounds of the present invention are believed to affect their activity by inhibition of CD73, a precise understanding of the compounds' underlying mechanism of action is not required to practice the invention. For example, the compounds can also affect their activity, at least in part, through modulation (e.g., inhibition) of other components of the purinergic signaling pathway (e.g., CD39). The purinergic signaling system consists of transporters, enzymes and receptors responsible for the synthesis, release, action, and extracellular inactivation of (primarily) ATP and its extracellular breakdown product adenosine (Sperlagh, B. et al. (Dec 2012) Neuropsychopharmacologia Hungarica 14(4):231-38). Figure 1 depicts a simplified representation of extracellular purinergic signaling (see, e.g., North RA (Oct 2002) Physiological Reviews 82(4): 1013-67). As indicated therein, there are several potential opportunities for modulation of the signaling process. However, as will be apparent to the skilled artisan, some of these opportunities are more tractable than others.

Identification of CD73 inhibitors Possessing Desirable Characteristics

[0087] The present invention is drawn, in part, to the identification of inhibitors of CD73 with at least one property or characteristic that is of therapeutic relevance. Candidate inhibitors may be identified by using, for example, an art-accepted assay or model, examples of which are will be apparent to the skilled artisan. The assay used to determine the CD73 inhibitory activity of the compounds described herein is set forth in the Experimental section.

[0088] After identification, candidate inhibitors can be further evaluated by using techniques that provide data regarding characteristics of the inhibitors (e.g., pharmacokinetic parameters). Comparisons of the candidate inhibitors to a reference standard (which may the "best-of-class" of current inhibitors) are indicative of the potential viability of such candidates.

[0089] CD73 inhibitors that can serve as reference or benchmark compounds include α,β- Methyl ene-ADP (AOPCP) and its derivatives and analogs described by Bhattarai et al. ((2015) J Med Chem 58:6248-63) and the purine CD73 derivatives reported in PCT Publn. 2015/164573. Other reference compounds subsequently identified by the skilled artisan can also be used to assess the viability of candidate CD73 inhibitors.

Compounds of the Invention

[0090] Provided herein are compounds having Formula (I): or a pharmaceutically acceptable salt, hydrate, or solvate thereof, wherein,

R la and R lb are independently selected from the group consisting of hydrogen, optionally

substituted Ci-C 6 alkyl, optionally substituted aryl, optionally substituted -C(R 2a R 2b )- aryl, -C(R 2a R 2b )-0-C(0)-OR 3 , -C(R 2a R 2b )-0-C(0)R 3 , and -C(R 2a R 2b )C(0)OR 3 ;

optionally, R la and R lb groups are combined to form a 5- to 6-membered heterocyclic ring;

each R 2a and R 2b is independently selected from the group consisting of H and optionally

substituted Ci-C 6 alkyl;

each R 3 is independently selected from the group consisting of H, Ci-C 6 alkyl, C1-C4 alkoxy(Ci-

C 4 )alkyl and optionally substituted aryl;

R 5a and R 5b are independently selected from the group consisting of H, optionally substituted Ci-

C 6 alkyl, -C(0)OR 3 , C 3 -C 6 cycloalkyl(Ci-C 6 )alkyl and aryl(Ci-C 6 )alkyl; each X is selected from the group consisting of O, NH, and S;

A is selected from the roup consisting of:

each of which is optionally substituted with from 1 to 5 R 6 substituents, and wherein the subscript n is an integer from 0 to 3;

Z is selected from the group consisting of NH, NR 6 , and O;

each R 6 is independently selected from the group consisting of C¾, OR g , CN, F, and optionally substituted Ci-C 6 alkyl; or two R 6 groups on adjacent ring vertices are optionally joined together to form a 5- to 6-membered ring having at least one heteroatom as a ring vertex; and

Het is selected from the group consisting of:

wherein the wavy line indicates the point of attachment to the remainder of the compound, wherein each G, when present, is independently selected from the group consisting of N and CR e and wherein:

R a is selected from the group consisting of H, H 2 , HR 7a , HC(0)R 7a , R 7a R 7b , R 7a , OH, SR 7: and OR 7a ;

R b is selected from the group consisting of H, halogen, H 2 , HR 7a , R 7a R 7b , R 7a , OH, and OR 7a ; R c and R d are independently selected from the group consisting of H, halogen, haloalkyl, H 2 , HR 7a , R 7a R 7b , R 7a , OH, OR 7a , SR 7a ,

S0 2 R 7a , -X^NHz, -X^ HR 73 , -X^NR^R 713 , -X^OH, -X^OR 73 , -X^SR 73

and -X^SOzR 73 ;

each R e is independently selected from the group consisting of H, halogen, and optionally

substituted Ci-C 6 alkyl;

each R g is independently selected from the group consisting of H and -C(0)-Ci-C 6 alkyl;

each X 1 is Ci-C4alkylene; and

each R 7a and R 7b is independently selected from the group consisting of optionally substituted

Ci-Cio alkyl, optionally substituted C 2 -Cio alkenyl, optionally substituted C 2 -Cio alkynyl, optionally substituted C3-C7 cycloalkyl, optionally substituted C3-C7 cycloalkylCi-C4alkyl, optionally substituted 4-7 membered cycloheteroalkyl, optionally substituted 4-7 membered cycloheteroalkylCi-C4alkyl, optionally substituted aryl, optionally substituted arylCi-C4alkyl, optionally substituted arylC 2 -C4alkenyl, optionally substituted arylC 2 -C4alkynyl, optionally substituted heteroaryl, optionally substituted heteroarylCi-C4alkyl, optionally substituted heteroarylCi-C4alkenyl, and optionally substituted heteroarylC 2 -C4alkynyl; or R 7a and R 713 when attached to the same nitrogen atom are optionally joined together to form a 4- to 7-membered heterocyclic ring, optionally fused to an aryl ring.

[0091] For the above formula, the term Optionally substituted' is used in connection with alkyl groups, cycloalkyl groups, cycloheteroalkyl groups, aryl groups and heteroaryl groups. Within each of these groups, some selected optional substituents are as follows:

Alkyl groups: halogen, -OR', -NR'R", -SR', -SiR'R"R"', -OC(0)R', -C(0)R', -C0 2 R', -

CONR'R", -OC(0)NR'R", -NR"C(0)R', -NR'-C(0)NR"R"', -NR"C(0) 2 R', -CN and -N0 2 . R', R" and R'" each independently refer to hydrogen, unsubstituted C1-4 alkyl, or C1-4 haloalkyl. When R' and R" are attached to the same nitrogen atom, or when R" and R"'are attached to the same nitrogen, they can be combined with the nitrogen atom to form a 3-, 4-, 5-, 6-, or 7-membered ring. For example, -NR'R" is meant to include 1-pyrrolidinyl and 4- morpholinyl. Cycloalkyl groups and cycloheteroalkyl groups: The selected substituents noted above for 'alkyl groups' are also useful with cycloalkyl and cycloheteroalkyl groups. Addtionally, each of the cycloalkyl and cycloheteroalkyl groups can be optionally substituted with oxo (=0).

Aryl groups and heteroaryl groups: -halogen, -OR', -OC(0)R', -NR'R", -R\ -CN, -N0 2 , - C0 2 R', -CONR'R", -C(0)R\ -OC(0)NR'R", -NR"C(0)R', -NR"C(0) 2 R', -NR'-

C(0)NR"R"', -S(0) 2 R', -S(0) 2 NR'R", -NR'S(0) 2 R", and perfiuoro(Ci-C 4 )alkyl, where R', R" and R'" are independently selected from hydrogen, Ci- 4 alkyl, Ci -4 haloalkyl and C3-6 cycloalkyl.

[0092] In some embodiments, R la and R lb groups can be combined to form a 5- to 6- membered heterocyclic ring. In such embodiments, any suitable portion of the R la group and R lb group may for a covalent bond thereby forming a heterocyclic ring. For example, in one set of embodiments, R la can be a substituted benzyl group, and R lb can be an ethyl group where the 2- position of the ethyl group and the benzylic carbon form a covalent bond. In another set of embodiments, R la can be a phenyl group and R lb can be methyl group where the ortho position of the phenyl group and the methyl form a covalent bond. In still further embodiments, R a can be a propyl group, and R lb can be a butyl group where the 1 -position of the propyl group and the 2-position of the ethyl group form a covalent bond. Other combinations of R la and R lb are also contemplated.

[0093] In one selected group of embodiments, compounds of Formula (I) are provided wherein A has the formula: which is optionally substituted with from 1 to 5 R 6 . The optional R 6 substituents as part of A in addition to the R 6 substituent that is present when Z is R 6 .

[0094] In another selected group of embodiments, compounds of Formula (I) are provided wherein A has a formula selected from the group consisting of:

wherein each R g is independently selected from the group consisting of H and C(0)-Ci-C 6 alkyl.

[0095] In still other selected embodiments, compounds of Formula (I) are provided wherein Het has the formula:

wherein each G is independently selected from the group consisting of N and CR e . In some selected embodiments, R c is other than H.

[0096] In yet other selected embodiments, compounds of Formula (I) are provided that are represented by one of the following subformulae:

wherein each R g is independently selected from the group consisting of H and C(0)-Ci-C6 alkyl.

[0097] Still further selected embodiments of the subformulae above, are those wherein each X is oxygen. In other selected embodiments of the subformulae above, each X is oxygen and R e is hydrogen. In still other selected embodiments of the subformulae above, each X is oxygen, R e is hydrogen, and each R g is hydrogen. [0098] Returning to Formula (I), in some embodiments, R is selected from the group consisting of H, optionally substituted Ci-4alkyl, -C(0)OR 3 , C3-C6 cycloalkyl(Ci-C4)alkyl and aryl(Ci-C 4 )alkyl, and R 5b is H.

[0099] In other embodiments, R 5a is selected from the group consisting of H, optionally substituted Ci -4 alkyl, -C(0)OR 3 , C 3 -C 6 cycloalkyl(Ci-C 4 )alkyl and aryl(Ci-C 4 )alkyl, R 5b is H, and each X is O.

[0100] In still other embodiments, R 5a is selected from the group consisting of H, optionally substituted Ci -4 alkyl, -C(0)OR 3 , C 3 -C 6 cycloalkyl(Ci-C 4 )alkyl and aryl(Ci-C 4 )alkyl, R 5b is H, each X is O, and R la and R lb are H. [0101] In another group of selected embodiments, compounds of Formula (I) are provided wherein Het is selected from:

wherein R a , R c and R e have the meanings provided with reference to Formula (I) above.

[0102] In some further selected embodiments of the subgenera described above, R 5a is selected from the group consisting of optionally substituted Ci -3 alkyl, -C(0)OH, C 3 -C 6 cycloalkyl(Ci- C 2 )alkyl and phenyl(Ci-C 2 )alkyl, R 5b is H, each X is O, and R la and R lb are H.

[0103] In still other selected embodiments of the subgenera described above, R 5a is selected from the group consisting of optionally substituted Ci -3 alkyl, -C(0)OH, C 3 -C 6 cycloalkyl(Ci- C 2 )alkyl and phenyl(Ci-C 2 )alkyl, R 5b is H, each X is O, R la and R lb are H, R e is H, and R a is selected from the group consisting of H 2 , HR 7a and R 7a R 7b .

[0104] In yet other selected embodiments of the subgenera described above, R 5a is selected from the group consisting of optionally substituted Ci -3 alkyl, -C(0)OH, C 3 -C 6 cycloalkyl(Ci- C 2 )alkyl and phenyl(Ci-C 2 )alkyl, R 5b is H, each X is O, R la and R lb are H, R e is H, R c is other than H, and R a is HR 7a . [0105] In some embodiments of Formula (I) and the subgenera described herein, R a is selected from the group consisting of optionally substituted Ci-C4alkyl, C(0)OR 3 , aryl(Ci- C 4 )alkyl, C3-C8cycloalkyl(Ci-C 4 )alkyl. In further selected embodiments, R 5a is selected from the group consisting of methyl, ethyl, ethyl-2-ol, C(0)OH, benzyl, and cyclopropylmethyl. [0106] In some embodiments of Formula (I) and the subgenera described herein, R a , when present, is HR 7a or R 7a R 7b and R 7a is selected from the group consisting of optionally substituted C3-C7 cycloalkyl, optionally substituted C3-C7 cycloalkylCi-C 4 alkyl, optionally substituted 4-7 membered cycloheteroalkyl, and optionally substituted 4-7 membered cycloheteroalkylCi-C 4 alkyl. R 713 , when present, is Ci -4 alkyl. [0107] In some embodiments of Formula (I) and the subgenera described herein, R a , when present, is HR 7a or R 7a R 7b and R 7a is C3-C7 cycloalkyl, or 4-7 membered cycloheteroalkylCi- C 4 alkyl. R 713 , when present, is Ci -4 alkyl.

[0108] In some embodiments of Formula (I) and the subgenera described herein, R a , when present, is HR 7a or R 7a R 7b and R 7a is cyclopentyl. R 7b , when present, is Ci -4 alkyl. [0109] Still other selected embodiments of the Formula (I), are compounds having a subformulae selected from the following:

(Ila) (Ilia)

wherein X, R la , R lb , R 5a , R 7a , R 713 and R c have the meanings provided with respect to Formula (I), and certain selected embodiments as described herein; and each R g is independently selected from the group consisting of H and C(0)-Ci-C 6 alkyl.

[0110] In some selected embodiments of formulae Ila, Ilia, lie, and IIIc, R la and R lb are H; each X is O; R g is H; and R c is CI. In still other embodiments of these formulae, R 5a is selected from the group consisting of methyl, ethyl and cyclopropylmethyl. [0111] In some selected embodiments of formulae lib, Illb, lid, and Hid, R and R are H; each X is O; R g is H; R c is CI; and R 7b is CH 3 . In still other embodiments of these formulae, R 5a is selected from the group consisting of methyl, ethyl and cyclopropylmethyl.

[0112] In still other selected embodiments, compounds are provided as set out in Table 1.

Methods of Synthesis

[0113] In general, the compounds provided herein can be prepared by conventional methods as described in the Examples below.

Modifications to Enhance Inhibitor Characteristics

[0114] It is frequently beneficial, and sometimes imperative, to improve one of more physical properties of the treatment modalities disclosed herein and/or the manner in which they are administered. Improvements of physical properties include, for example, methods of increasing water solubility, bioavailability, serum half-life, and/or therapeutic half-life; and/or modulating biological activity.

[0115] Modifications known in the art include pegylation, Fc-fusion and albumin fusion.

Although generally associated with large molecule agents (e.g., polypeptides), such

modifications have recently been evaluated with particular small molecules. By way of example, Chiang, M. et al. (J. Am. Chem. Soc, 2014, 136(9):3370-73) describe a small molecule agonist of the adenosine 2a receptor conjugated to the immunoglobulin Fc domain. The small molecule- Fc conjugate retained potent Fc receptor and adenosine 2a receptor interactions and showed superior properties compared to the unconjugated small molecule. Covalent attachment of PEG molecules to small molecule therapeutics has also been described (Li, W. et al., Progress in Polymer Science, 2013 38:421-44).

Therapeutic and Prophylactic Uses [0116] The present invention contemplates the use of the CD73 inhibitors described herein in the treatment or prevention of a broad range of diseases, disorders and/or conditions, and/or the symptoms thereof. While particular uses are described in detail hereafter, it is to be understood that the present invention is not so limited. Furthermore, although general categories of particular diseases, disorders and conditions are set forth hereafter, some of the diseases, disorders and conditions may be a member of more than one category, and others may not be a member of any of the disclosed categories.

[0117] Oncology-related Disorders. In accordance with the present invention, an CD73 inhibitor can be used to treat or prevent a proliferative condition or disorder, including a cancer, for example, cancer of the uterus, cervix, breast, prostate, testes, gastrointestinal tract (e.g., esophagus, oropharynx, stomach, small or large intestines, colon, or rectum), kidney, renal cell, bladder, bone, bone marrow, skin, head or neck, liver, gall bladder, heart, lung, pancreas, salivary gland, adrenal gland, thyroid, brain (e.g., gliomas), ganglia, central nervous system (CNS) and peripheral nervous system (PNS), and cancers of the hematopoietic system and the immune system (e.g., spleen or thymus). The present invention also provides methods of treating or preventing other cancer-related diseases, disorders or conditions, including, for example, immunogenic tumors, non-immunogenic tumors, dormant tumors, virus-induced cancers (e.g., epithelial cell cancers, endothelial cell cancers, squamous cell carcinomas and papillomavirus), adenocarcinomas, lymphomas, carcinomas, melanomas, leukemias, myelomas, sarcomas, teratocarcinomas, chemically-induced cancers, metastasis, and angiogenesis. The invention contemplates reducing tolerance to a tumor cell or cancer cell antigen, e.g., by modulating activity of a regulatory T-cell and/or a CD8+ T-cell (see, e.g., Ramirez-Montagut, et al. (2003) Oncogene 22:3180-87; and Sawaya, et al. (2003) New Engl. J. Med. 349: 1501-09). In particular embodiments, the tumor or cancer is colon cancer, ovarian cancer, breast cancer, melanoma, lung cancer, glioblastoma, or leukemia. The use of the term(s) cancer-related diseases, disorders and conditions is meant to refer broadly to conditions that are associated, directly or indirectly, with cancer, and includes, e.g., angiogenesis and precancerous conditions such as dysplasia. [0118] In certain embodiments, a cancer be metastatic or at risk of becoming metastatic, or may occur in a diffuse tissue, including cancers of the blood or bone marrow (e.g., leukemia). In some further embodiments, the compounds of the invention can be used to overcome T-cell tolerance. [0119] In some embodiments, the present invention provides methods for treating a proliferative condition, cancer, tumor, or precancerous condition with an CD73 inhibitor and at least one additional therapeutic or diagnostic agent, examples of which are set forth elsewhere herein.

[0120] Immune-related Disorders and Disorders with an Inflammatory Component. As used herein, terms such as "immune disease", "immune condition", "immune disorder",

"inflammatory disease", "inflammatory condition", "inflammatory disorder" and the like are meant to broadly encompass any immune-related condition (e.g., an autoimmune disease) or a disorder with an inflammatory component that can be treated by the CD73 inhibitors described herein such that some therapeutic benefit is obtained. Such conditions frequently are

inextricably intertwined with other diseases, disorders and conditions. By way of example, an "immune condition" may refer to proliferative conditions, such as cancer, tumors, and angiogenesis; including infections (acute and chronic), tumors, and cancers that resist eradication by the immune system.

[0121] The CD73 inhibitors of the present invention can be used to increase or enhance an immune response; to improve immunization, including increasing vaccine efficacy; and to increase inflammation. Immune deficiencies associated with immune deficiency diseases, immunosuppressive medical treatment, acute and/or chronic infection, and aging can be treated using the compounds disclosed herein. The CD73 inhibitors can also be used to stimulate the immune system of patients suffering from iatrogenically-induced immune suppression, including those who have undergone bone marrow transplants, chemotherapy, or radiotherapy.

[0122] In particular embodiments of the present disclosure, the CD73 inhibitors are used to increase or enhance an immune response to an antigen by providing adjuvant activity. In a particular embodiment, at least one antigen or vaccine is administered to a subject in combination with at least one CD73 inhibitor of the present invention to prolong an immune response to the antigen or vaccine. Therapeutic compositions are also provided which include at least one antigenic agent or vaccine component, including, but not limited to, viruses, bacteria, and fungi, or portions thereof, proteins, peptides, tumor-specific antigens, and nucleic acid vaccines, in combination with at least one CD73 inhibitor of the present invention.

[0123] Microbial-related Disorders. By inhibiting the immunosuppressive and antiinflammatory activity of CD73, the present invention contemplates the use of the CD73 inhibitors described herein in the treatment and/or prevention of any viral, bacterial, fungal, parasitic or other infective disease, disorder or condition for which treatment with an CD73 inhibitor may be beneficial. Examples of such diseases and disorders include HIV and AIDS, staphylococcal and streptococcal infections (e.g., Staphylococcus aureus and streptococcus sanguinis, respectively), leishmania, toxoplasma, trichomonas, giardia, Candida albicans, bacillus anthracis, and pseudomonas aeruginosa. Compounds of the invention can be used to treat sepsis, decrease or inhibit bacterial growth, and reduce or inhibit inflammatory cytokines. [0124] CNS-related and Neurological Disorders. Inhibition of CD73 may also be an important treatment strategy for patients with neurological, neuropsychiatric, neurodegenerative or other diseases, disorders and conditions having some association with the central nervous system, including disorders associated with impairment of cognitive function and motor function.

Examples include Parkinson's disease, extra pyramidal syndrome (EPS), dystonia, akathisia, tardive dyskinesia, restless leg syndrome (RLS), epilepsy, periodic limb movement in sleep (PLMS), attention deficit disorders, depression, anxiety, dementia, Alzheimer's disease,

Huntington's disease, multiple sclerosis, cerebral ischemia, hemorrhagic stroke, subarachnoid hemorrhage, and traumatic brain injury.

[0125] Other Disorders. Embodiments of the present invention contemplate the administration of the CD73 inhibitors described herein to a subject for the treatment or prevention of any other disorder that may benefit from at least some level of CD73 inhibition. Such diseases, disorders and conditions include, for example, cardiovascular (e.g., cardiac ischemia), gastrointestinal (e.g., Crohn's disease), metabolic (e.g., diabetes), hepatic (e.g., hepatic fibrosis, NASH, and NAFLD), pulmonary (e.g., COPD and asthma), ophthalmologic (e.g., diabetic retinopathy), and renal (e.g., renal failure) disorders.

[0126] In some embodiments, the CD73 inhibitors of the present invention may be used to inhibit statin-induced adenosine production, or reduce or decrease increases in blood glucose caused by a statin in a subject taking a statin (e.g., lovastatin and pravastatin)

Pharmaceutical Compositions

[0127] The CD73 inhibitors of the present invention may be in the form of compositions suitable for administration to a subject. In general, such compositions are "pharmaceutical compositions" comprising an CD73 inhibitor(s) and one or more pharmaceutically acceptable or physiologically acceptable diluents, carriers or excipients. In certain embodiments, the CD73 inhibitors are present in a therapeutically acceptable amount. The pharmaceutical compositions may be used in the methods of the present invention; thus, for example, the pharmaceutical compositions can be administered ex vivo or in vivo to a subject in order to practice the therapeutic and prophylactic methods and uses described herein.

[0128] The pharmaceutical compositions of the present invention can be formulated to be compatible with the intended method or route of administration; exemplary routes of administration are set forth herein. Furthermore, the pharmaceutical compositions may be used in combination with other therapeutically active agents or compounds as described herein in order to treat or prevent the diseases, disorders and conditions as contemplated by the present invention.

[0129] The pharmaceutical compositions containing the active ingredient (e.g., an inhibitor of CD73 function) may be in a form suitable for oral use, for example, as tablets, capsules, troches, lozenges, aqueous or oily suspensions, dispersible powders or granules, emulsions, hard or soft capsules, or syrups, solutions, microbeads or elixirs. Pharmaceutical compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions, and such compositions may contain one or more agents such as, for example, sweetening agents, flavoring agents, coloring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparations. Tablets, capsules and the like contain the active ingredient in admixture with non-toxic pharmaceutically acceptable excipients which are suitable for the manufacture of tablets. These excipients may be, for example, diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents, for example, corn starch, or alginic acid;

binding agents, for example starch, gelatin or acacia, and lubricating agents, for example magnesium stearate, stearic acid or talc.

[0130] Tablets, capsules and the like, suitable for oral administration, may be uncoated or coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action. For example, a time-delay material such as glyceryl monostearate or glyceryl distearate may be employed. They may also be coated by techniques known in the art to form osmotic therapeutic tablets for controlled release. Additional agents include biodegradable or biocompatible particles or a polymeric substance such as polyesters, polyamine acids, hydrogel, polyvinyl pyrrolidone, polyanhydrides, polyglycolic acid, ethylene- vinylacetate, methylcellulose, carboxymethylcellulose, protamine sulfate, or lactide/glycolide copolymers, polylactide/glycolide copolymers, or ethylenevinylacetate copolymers in order to control delivery of an administered composition. For example, the oral agent can be entrapped in microcapsules prepared by coacervation techniques or by interfacial polymerization, by the use of hydroxymethylcellulose or gelatin-mi crocapsules or poly (methylmethacrolate) microcapsules, respectively, or in a colloid drug delivery system. Colloidal dispersion systems include macromolecule complexes, nano-capsules, microspheres, microbeads, and lipid-based systems, including oil-in-water emulsions, micelles, mixed micelles, and liposomes. Methods for the preparation of the above-mentioned formulations will be apparent to those skilled in the art. [0131] Formulations for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example, calcium carbonate, calcium phosphate, kaolin or microcrystalline cellulose, or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example peanut oil, liquid paraffin, or olive oil. [0132] Aqueous suspensions contain the active materials in admixture with excipients suitable for the manufacture thereof. Such excipients can be suspending agents, for example sodium carboxymethylcellulose, methylcellulose, hydroxy-propylmethylcellulose, sodium alginate, polyvinyl-pyrrolidone, gum tragacanth and gum acacia; dispersing or wetting agents, for example a naturally-occurring phosphatide (e.g., lecithin), or condensation products of an alkylene oxide with fatty acids (e.g., polyoxy-ethylene stearate), or condensation products of ethylene oxide with long chain aliphatic alcohols (e.g., for heptadecaethyleneoxycetanol), or condensation products of ethylene oxide with partial esters derived from fatty acids and a hexitol (e.g., poly oxy ethylene sorbitol monooleate), or condensation products of ethylene oxide with partial esters derived from fatty acids and hexitol anhydrides (e.g., polyethylene sorbitan monooleate). The aqueous suspensions may also contain one or more preservatives.

[0133] Oily suspensions may be formulated by suspending the active ingredient in a vegetable oil, for example arachis oil, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin. The oily suspensions may contain a thickening agent, for example beeswax, hard paraffin or cetyl alcohol. Sweetening agents such as those set forth above, and flavoring agents may be added to provide a palatable oral preparation.

[0134] Dispersible powders and granules suitable for preparation of an aqueous suspension by the addition of water provide the active ingredient in admixture with a dispersing or wetting agent, suspending agent and one or more preservatives. Suitable dispersing or wetting agents and suspending agents are exemplified herein.

[0135] The pharmaceutical compositions provided herein may also be in the form of oil-in- water emulsions. The oily phase may be a vegetable oil, for example olive oil or arachis oil, or a mineral oil, for example, liquid paraffin, or mixtures of these. Suitable emulsifying agents may be naturally occurring gums, for example, gum acacia or gum tragacanth; naturally occurring phosphatides, for example, soy bean, lecithin, and esters or partial esters derived from fatty acids; hexitol anhydrides, for example, sorbitan monooleate; and condensation products of partial esters with ethylene oxide, for example, polyoxyethylene sorbitan monooleate. [0136] The pharmaceutical compositions typically comprise a therapeutically effective amount of an CD73 inhibitor contemplated by the present invention and one or more pharmaceutically and physiologically acceptable formulation agents. Suitable pharmaceutically acceptable or physiologically acceptable diluents, carriers or excipients include, but are not limited to, antioxidants (e.g., ascorbic acid and sodium bisulfate), preservatives (e.g., benzyl alcohol, methyl parabens, ethyl or n-propyl, p-hydroxybenzoate), emulsifying agents, suspending agents, dispersing agents, solvents, fillers, bulking agents, detergents, buffers, vehicles, diluents, and/or adjuvants. For example, a suitable vehicle may be physiological saline solution or citrate buffered saline, possibly supplemented with other materials common in pharmaceutical compositions for parenteral administration. Neutral buffered saline or saline mixed with serum albumin are further exemplary vehicles. Those skilled in the art will readily recognize a variety of buffers that can be used in the pharmaceutical compositions and dosage forms contemplated herein. Typical buffers include, but are not limited to, pharmaceutically acceptable weak acids, weak bases, or mixtures thereof. As an example, the buffer components can be water soluble materials such as phosphoric acid, tartaric acids, lactic acid, succinic acid, citric acid, acetic acid, ascorbic acid, aspartic acid, glutamic acid, and salts thereof. Acceptable buffering agents include, for example, a Tris buffer, N-(2-Hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid) (HEPES), 2-(N-Morpholino)ethanesulfonic acid (MES), 2-(N-Morpholino)ethanesulfonic acid sodium salt (MES), 3-(N-Morpholino)propanesulfonic acid (MOPS), and N- tris[Hydroxymethyl]methyl-3-aminopropanesulfonic acid (TAPS).

[0137] After a pharmaceutical composition has been formulated, it may be stored in sterile vials as a solution, suspension, gel, emulsion, solid, or dehydrated or lyophilized powder. Such formulations may be stored either in a ready-to-use form, a lyophilized form requiring reconstitution prior to use, a liquid form requiring dilution prior to use, or other acceptable form. In some embodiments, the pharmaceutical composition is provided in a single-use container

(e.g., a single-use vial, ampoule, syringe, or autoinjector (similar to, e.g., an EpiPen®)), whereas a multi-use container (e.g., a multi-use vial) is provided in other embodiments.

[0138] Formulations can also include carriers to protect the composition against rapid degradation or elimination from the body, such as a controlled release formulation, including liposomes, hydrogels, prodrugs and microencapsulated delivery systems. For example, a time delay material such as glyceryl monostearate or glyceryl stearate alone, or in combination with a wax, may be employed. Any drug delivery apparatus may be used to deliver an CD73 inhibitor, including implants (e.g., implantable pumps) and catheter systems, slow injection pumps and devices, all of which are well known to the skilled artisan.

[0139] Depot injections, generally administered subcutaneously or intramuscularly, can also be utilized to release the CD73 inhibitors disclosed herein over a defined period of time. Depot injections are usually either solid- or oil-based and generally comprise at least one of the formulation components set forth herein. One of ordinary skill in the art is familiar with possible formulations and uses of depot injections.

[0140] Pharmaceutical compositions as provided herein can also be in the form of a sterile injectable aqueous or oleagenous suspensions. This suspension may be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents mentioned herein. The sterile injectable preparation may also be a sterile injectable solution or suspension in a non-toxic parenterally-acceptable diluent or solvent, for example, as a solution in 1,3 -butane diol. Acceptable diluents, solvents and dispersion media that may be employed include water, Ringer's solution, isotonic sodium chloride solution, Cremophor EL™ (BASF, Parsippany, NJ) or phosphate buffered saline (PBS), ethanol, polyol (e.g., glycerol, propylene glycol, and liquid polyethylene glycol), and suitable mixtures thereof. In addition, sterile, fixed oils are

conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed, including synthetic mono- or diglycerides. Moreover, fatty acids such as oleic acid, find use in the preparation of injectables. Prolonged absorption of particular injectable formulations can be achieved by including an agent that delays absorption (e.g., aluminum monostearate or gelatin). [0141] The present invention contemplates the administration of the CD73 inhibitors in the form of suppositories for rectal administration. The suppositories can be prepared by mixing the drug with a suitable non-irritating excipient which is solid at ordinary temperatures but liquid at the rectal temperature and will therefore melt in the rectum to release the drug. Such materials include, but are not limited to, cocoa butter and polyethylene glycols. [0142] The CD73 inhibitors contemplated by the present invention may be in the form of any other suitable pharmaceutical composition (e.g., sprays for nasal or inhalation use) currently known or developed in the future.

Routes of Administration

[0143] The present invention contemplates the administration of CD73 inhibitors, and compositions thereof, in any appropriate manner. Suitable routes of administration include oral, parenteral (e.g., intramuscular, intravenous, subcutaneous (e.g., injection or implant),

intraperitoneal, intracisternal, intraarticular, intraperitoneal, intracerebral (intraparenchymal) and intracerebroventricular), nasal, vaginal, sublingual, intraocular, rectal, topical (e.g., transdermal), buccal and inhalation. Depot injections, which are generally administered subcutaneously or intramuscularly, may also be utilized to release the CD73 inhibitors disclosed herein over a defined period of time.

[0144] Particular embodiments of the present invention contemplate oral administration.

Combination Therapy

[0145] The present invention contemplates the use of CD73 inhibitors alone or in combination with one or more active therapeutic agents. The additional active therapeutic agents can be small chemical molecules; macromolecules such as proteins, antibodies, peptibodies, peptides, DNA, RNA or fragments of such macromolecules; or cellular or gene therapies. In such combination therapy, the various active agents frequently have different, complementary mechanisms of action. Such combination therapy may be especially advantageous by allowing a dose reduction of one or more of the agents, thereby reducing or eliminating the adverse effects associated with one or more of the agents. Furthermore, such combination therapy may have a synergistic therapeutic or prophylactic effect on the underlying disease, disorder, or condition.

[0146] As used herein, "combination" is meant to include therapies that can be administered separately, for example, formulated separately for separate administration (e.g., as may be provided in a kit), and therapies that can be administered together in a single formulation (i.e., a "co-formulation").

[0147] In certain embodiments, the CD73 inhibitors are administered or applied sequentially, e.g., where one agent is administered prior to one or more other agents. In other embodiments, the CD73 inhibitors are administered simultaneously, e.g., where two or more agents are administered at or about the same time; the two or more agents may be present in two or more separate formulations or combined into a single formulation (i.e., a co-formulation). Regardless of whether the two or more agents are administered sequentially or simultaneously, they are considered to be administered in combination for purposes of the present invention. [0148] The CD73 inhibitors of the present invention may be used in combination with at least one other (active) agent in any manner appropriate under the circumstances. In one embodiment, treatment with the at least one active agent and at least one CD73 inhibitor of the present invention is maintained over a period of time. In another embodiment, treatment with the at least one active agent is reduced or discontinued (e.g., when the subject is stable), while treatment with an CD73 inhibitor of the present invention is maintained at a constant dosing regimen. In a further embodiment, treatment with the at least one active agent is reduced or discontinued (e.g., when the subject is stable), while treatment with an CD73 inhibitor of the present invention is reduced (e.g., lower dose, less frequent dosing or shorter treatment regimen). In yet another embodiment, treatment with the at least one active agent is reduced or discontinued (e.g., when the subject is stable), and treatment with the CD73 inhibitor of the present invention is increased (e.g., higher dose, more frequent dosing or longer treatment regimen). In yet another

embodiment, treatment with the at least one active agent is maintained and treatment with the CD73 inhibitor of the present invention is reduced or discontinued (e.g., lower dose, less frequent dosing or shorter treatment regimen). In yet another embodiment, treatment with the at least one active agent and treatment with the CD73 inhibitor of the present invention are reduced or discontinued (e.g., lower dose, less frequent dosing or shorter treatment regimen).

[0149] Oncology-related Disorders. The present invention provides methods for treating and/or preventing a proliferative condition, cancer, tumor, or precancerous disease, disorder or condition with an CD73 inhibitor and at least one additional therapeutic or diagnostic agent. [0150] In certain embodiments, the present invention provides methods for tumor suppression of tumor growth comprising administration of an CD73 inhibitor described herein in

combination with a signal transduction inhibitor (STI) to achieve additive or synergistic suppression of tumor growth. As used herein, the term "signal transduction inhibitor" refers to an agent that selectively inhibits one or more steps in a signaling pathway. Signal transduction inhibitors (STIs) of the present invention include: (i) bcr/abl kinase inhibitors (e.g., GLEEVEC); (ii) epidermal growth factor (EGF) receptor inhibitors, including kinase inhibitors and antibodies; (iii) her-2/neu receptor inhibitors (e.g., HERCEPTIN); (iv) inhibitors of Akt family kinases or the Akt pathway (e.g., rapamycin); (v) cell cycle kinase inhibitors (e.g., flavopiridol); and (vi) phosphatidyl inositol kinase inhibitors. Agents involved in in immunomodulation can also be used in combination with the CD73 inhibitors described herein for the suppression of tumor growth in cancer patients.

[0151] Examples of chemotherapeutic agents include, but are not limited to, alkylating agents such as thiotepa and cyclosphosphamide; alkyl sulfonates such as busulfan, improsulfan and piposulfan; aziri dines such as benzodopa, carboquone, meturedopa, and uredopa; ethyl enimines and methylamelamines including altretamine, triethylenemelamine, trietylenephosphoramide, triethylenethiophosphaoramide and trimethylolomelamime; nitrogen mustards such as chlorambucil, chlornaphazine, cholophosphamide, estramustine, ifosfamide, mechlorethamine, mechlorethamine oxide hydrochloride, melphalan, novembichin, phenesterine, prednimustine, trofosfamide, uracil mustard; nitrosureas such as carmustine, chlorozotocin, fotemustine, lomustine, nimustine, ranimustine; antibiotics such as aclacinomysins, actinomycin,

authramycin, azaserine, bleomycins, cactinomycin, calicheamicin, carabicin, caminomycin, carzinophilin, chromomycins, dactinomycin, daunorubicin, detorubicin, 6-diazo-5-oxo-L- norleucine, doxorubicin, epirubicin, esorubicin, idarubicin, marcellomycin, mitomycins, mycophenolic acid, nogalamycin, olivomycins, peplomycin, potfiromycin, puromycin, quelamycin, rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex, zinostatin, zorubicin; anti-metabolites such as methotrexate and 5-fluorouracil (5-FU); folic acid analogs such as denopterin, methotrexate, pteropterin, trimetrexate; purine analogs such as fludarabine, 6- mercaptopurine, thiamiprine, thioguanine; pyrimidine analogs such as ancitabine, azacitidine, 6- azauridine, carmofur, cytarabine, dideoxyuridine, doxifluridine, enocitabine, floxuridine, 5-FU; androgens such as calusterone, dromostanolone propionate, epitiostanol, mepitiostane, testolactone; anti-adrenals such as aminoglutethimide, mitotane, trilostane; folic acid replenish er such as frolinic acid; aceglatone; aldophosphamide glycoside; aminolevulinic acid; amsacrine; bestrabucil; bisantrene; edatraxate; defofamine; demecolcine; diaziquone; elformithine;

elliptinium acetate; etoglucid; gallium nitrate; hydroxyurea; lentinan; lonidamine; mitoguazone; mitoxantrone; mopidamol; nitracrine; pentostatin; phenamet; pirarubicin; podophyllinic acid; 2- ethylhydrazide; procarbazine; razoxane; sizofiran; spirogermanium; tenuazonic acid; triaziquone;

2,2',2"-trichlorotriethylamine; urethan; vindesine; dacarbazine; mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine; arabinoside (Ara-C); cyclophosphamide; thiotepa; taxoids, e.g., paclitaxel and doxetaxel; chlorambucil; gemcitabine; 6-thioguanine; mercaptopurine;

methotrexate; platinum and platinum coordination complexes such as cisplatin and carboplatin; vinblastine; etoposide (VP- 16); ifosfamide; mitomycin C; mitoxantrone; vincristine; vinorelbine; navelbine; novantrone; teniposide; daunomycin; aminopterin; xeloda; ibandronate; CPT11;

topoisomerase inhibitors; difluoromethylornithine (DMFO); retinoic acid; esperamicins;

capecitabine; and pharmaceutically acceptable salts, acids or derivatives of any of the above.

[0152] Chemotherapeutic agents also include anti-hormonal agents that act to regulate or inhibit hormonal action on tumors such as anti-estrogens, including for example tamoxifen, raloxifene, aromatase inhibiting 4(5)-imidazoles, 4-hydroxytamoxifen, trioxifene, keoxifene, onapristone, and toremifene; and antiandrogens such as flutamide, nilutamide, bicalutamide, leuprolide, and goserelin; and pharmaceutically acceptable salts, acids or derivatives of any of the above. In certain embodiments, combination therapy comprises administration of a hormone or related hormonal agent.

[0153] Additional treatment modalities that may be used in combination with an CD73 inhibitor include radiotherapy, a monoclonal antibody against a tumor antigen, a complex of a monoclonal antibody and toxin, a T-cell adjuvant, bone marrow transplant, or antigen presenting cells (e.g., dendritic cell therapy), including TLR agonists which are used to stimulate such antigen presenting cells.

[0154] In certain embodiments, the present invention contemplates the use of the compounds described herein in combination with adoptive cell therapy, a new and promising form of personalized immunotherapy in which immune cells with anti-tumor activity are administered to cancer patients. Adoptive cell therapy is being explored using tumor-infiltrating lymphocytes (TIL) and T cells engineered to express, for example, chimeric antigen receptors (CAR) or T cell receptors (TCR). Adoptive cell therapy generally involves collecting T cells from an individual, genetically modifying them to target a specific antigen or to enhance their anti-tumor effects, amplifying them to a sufficient number, and infusion of the genetically modified T cells into a cancer patient. T cells can be collected from the patient to whom the expanded cells are later reinfused (e.g., autologous) or can be collected from donor patients (e.g., allogeneic).

[0155] In certain embodiments, the present invention contemplates the use of the compounds described herein in combination with RNA interference-based therapies to silence gene expression. RNAi begins with the cleavage of longer double-stranded RNAs into small interfering RNAs (siRNAs). One strand of the siRNA is incorporated into a ribonucleoprotein complex known as the RNA-induced silencing complex (RISC), which is then used to identify mRNA molecules that are at least partially complementary to the incorporated siRNA strand. RISC can bind to or cleave the mRNA, both of which inhibits translation.

[0156] Immune Checkpoint Inhibitors. The present invention contemplates the use of the inhibitors of CD73 function described herein in combination with immune checkpoint inhibitors.

[0157] The tremendous number of genetic and epigenetic alterations that are characteristic of all cancers provides a diverse set of antigens that the immune system can use to distinguish tumor cells from their normal counterparts. In the case of T cells, the ultimate amplitude (e.g., levels of cytokine production or proliferation) and quality (e.g., the type of immune response generated, such as the pattern of cytokine production) of the response, which is initiated through antigen recognition by the T-cell receptor (TCR), is regulated by a balance between co- stimulatory and inhibitory signals (immune checkpoints). Under normal physiological conditions, immune checkpoints are crucial for the prevention of autoimmunity (i.e., the maintenance of self-tolerance) and also for the protection of tissues from damage when the immune system is responding to pathogenic infection. The expression of immune checkpoint proteins can be dysregulated by tumors as an important immune resistance mechanism. [0158] Examples of immune checkpoints (ligands and receptors), some of which are selectively upregulated in various types of tumor cells, that are candidates for blockade include PD1 (programmed cell death protein 1); PDL1 (PD1 ligand); BTLA (B and T lymphocyte attenuator); CTLA4 (cytotoxic T-lymphocyte associated antigen 4); TIM3 (T-cell membrane protein 3); LAG3 (lymphocyte activation gene 3); TIGIT (T cell immunoreceptor with Ig and ITIM domains); A2aR (adenosine A2a receptor A2aR); and Killer Inhibitory Receptors, which can be divided into two classes based on their structural features: i) killer cell immunoglobulin- like receptors (KIRs), and ii) C-type lectin receptors (members of the type II transmembrane receptor family). Other less well-defined immune checkpoints have been described in the literature, including both receptors (e.g., the 2B4 (also known as CD244) receptor) and ligands (e.g., certain B7 family inhibitory ligands such B7-H3 (also known as CD276) and B7-H4 (also known as B7-S1, B7x and VCTNl)). [See Pardoll, (April 2012) Nature Rev. Cancer 12:252-64].

[0159] The present invention contemplates the use of the inhibitors of CD73 function described herein in combination with inhibitors of the aforementioned immune-checkpoint receptors and ligands, as well as yet-to-be-described immune-checkpoint receptors and ligands. Certain modulators of immune checkpoints are currently available, whereas others are in late- stage development. To illustrate, when it was approved for the treatment of melanoma in 2011, the fully humanized CTLA4 monoclonal antibody ipilimumab (YERVOY; Bristol-Myers Squibb) became the first immune checkpoint inhibitor to receive regulatory approval in the US. Fusion proteins comprising CTLA4 and an antibody (CTLA4-Ig; abatcept (ORENCIA; Bristol- Myers Squibb)) have been used for the treatment of rheumatoid arthritis, and other fusion proteins have been shown to be effective in renal transplantation patients that are sensitized to Epstein Barr Virus. PD1 antibodies are under development (e.g., nivolumab (Bristol-Myers Squibb) and lambrolizumab (Merck)), and anti-PDLl antibodies are also being evaluated (e.g., MPDL3280A (Roche)). Nivolumab has shown promise in patients with melanoma, lung and kidney cancer.

[0160] The present invention encompasses pharmaceutically acceptable salts, acids or derivatives of any of the above. [0161] Metabolic and Cardiovascular Diseases. The present invention provides methods for treating and/or preventing certain cardiovascular- and/or metabolic-related diseases, disorders and conditions, as well as disorders associated therewith, with an CD73 inhibitor and at least one additional therapeutic or diagnostic agent. [0162] Examples of therapeutic agents useful in combination therapy for the treatment of hypercholesterolemia (and atherosclerosis as well) include statins (e.g., CRESTOR, LESCOL, LIPITOR, MEVACOR, PRAVACOL, and ZOCOR), which inhibit the enzymatic synthesis of cholesterol; bile acid resins (e.g., COLESTID, LO-CHOLEST, PREVALITE, QUESTRAN, and WELCHOL), which sequester cholesterol and prevent its absorption; ezetimibe (ZETIA), which blocks cholesterol absorption; fibric acid (e.g., TRICOR), which reduces triglycerides and may modestly increase HDL; niacin (e.g., NIACOR), which modestly lowers LDL cholesterol and triglycerides; and/or a combination of the aforementioned (e.g., VYTORIN (ezetimibe with simvastatin). Alternative cholesterol treatments that may be candidates for use in combination with the CD73 inhibitors described herein include various supplements and herbs (e.g., garlic, policosanol, and guggul).

[0163] The present invention encompasses pharmaceutically acceptable salts, acids or derivatives of any of the above.

[0164] Immune-related Disorders and Disorders Having an Inflammatory Component. The present invention provides methods for treating and/or preventing immune-related diseases, disorders and conditions; and diseases, disorders and conditions having an inflammatory component; with an CD73 inhibitor and at least one additional therapeutic or diagnostic agent.

[0165] Examples of therapeutic agents useful in combination therapy are specific to the underlying disease, disorder or condition, and are known to the skilled artisan.

[0166] Microbial Diseases. The present invention provides methods for treating and/or preventing viral, bacterial, fungal and parasitic diseases, disorders and conditions, as well as disorders associated therewith, with an CD73 inhibitor and at least one additional therapeutic or diagnostic agent (e.g., one or more other antiviral agents and/or one or more agents not associated with viral therapy). [0167] Such combination therapy includes anti-viral agents targeting various viral life-cycle stages and having different mechanisms of action, including, but not limiting to, the following: inhibitors of viral uncoating (e.g., amantadine and rimantidine); reverse transcriptase inhibitors (e.g., acyclovir, zidovudine, and lamivudine); agents that target integrase; agents that block attachment of transcription factors to viral DNA; agents (e.g., antisense molecules) that impact translation (e.g., fomivirsen); agents that modulate translation/ribozyme function; protease inhibitors; viral assembly modulators (e.g., rifampicin); anti retroviral s such as, for example, nucleoside analogue reverse transcriptase inhibitors (e.g., azidothymidine (AZT), ddl, ddC, 3TC, d4T); non-nucleoside reverse transcriptase inhibitors (e.g., efavirenz, nevirapine); nucleotide analogue reverse transcriptase inhibitors; and agents that prevent release of viral particles (e.g., zanamivir and oseltamivir). Treatment and/or prevention of certain viral infections (e.g., HIV) frequently entail a group ("cocktail") of antiviral agents.

[0168] Other antiviral agents contemplated for use in combination with an CD73 inhibitor include, but are not limited to, the following: abacavir, adefovir, amantadine, amprenavir, ampligen, arbidol, atazanavir, atripla, boceprevirertet, cidofovir, combivir, darunavir, delavirdine, didanosine, docosanol, edoxudine, emtricitabine, enfuvirtide, entecavir, famciclovir, fosamprenavir, foscarnet, fosfonet, http://en.wikipedia.org/wiki/Fusion_inhibitor ganciclovir, ibacitabine, imunovir, idoxuridine, imiquimod, indinavir, inosine, various interferons (e.g., peginterferon alfa-2a), lopinavir, loviride, maraviroc, moroxydine, methisazone, nelfinavir, nexavir, penciclovir, peramivir, pleconaril, podophyllotoxin, raltegravir, ribavirin, ritonavir, pyramidine, saquinavir, stavudine, telaprevir, tenofovir, tipranavir, trifluridine, trizivir, tromantadine, truvada, valaciclovir, valganciclovir, vicriviroc, vidarabine, viramidine, and zalcitabine.

[0169] The present invention contemplates the use of the inhibitors of CD73 function described herein in combination with antiparasitic agents. Such agents include, but are not limited to, thiabendazole, pyrantel pamoate, mebendazole, praziquantel, niclosamide, bithionol, oxamniquine, metrifonate, ivermectin, albendazole, eflornithine, melarsoprol, pentamidine, benznidazole, nifurtimox, and nitroimidazole. The skilled artisan is aware of other agents that may find utility for the treatment of parasitic disorders. [0170] Embodiments of the present invention contemplate the use of the CD73 inhibitors described herein in combination with agents useful in the treatment or prevention of bacterial disorders. Antibacterial agents can be classified in various manners, including based on mechanism of action, based on chemical structure, and based on spectrum of activity. Examples of antibacterial agents include those that target the bacterial cell wall (e.g., cephalosporins and penicillins) or the cell membrane (e.g., polymyxins), or interfere with essential bacterial enzymes (e.g., sulfonamides, rifamycins, and quinolines). Most antibacterial agents that target protein synthesis (e.g., tetracyclines and macrolides) are bacteriostatic, whereas agents such as the aminoglycoside are bactericidal. Another means of categorizing antibacterial agents is based on their target specificity; "narrow-spectrum" agents target specific types of bacteria (e.g., Gram- positive bacteria such as Streptococcus), while "broad-spectrum" agents have activity against a broader range of bacteria. The skilled artisan is aware of types of anti -bacterial agents that are appropriate for use in specific bacterial infections.

[0171] Embodiments of the present invention contemplate the use of the CD73 inhibitors described herein in combination with agents useful in the treatment or prevention of fungal disorders. Antifungal agents include polyenes (e.g., amphotericin, nystatin, and pimaricin); azoles (e.g., fluconazole, itraconazole, and ketoconazole); allylamines (e.g., naftifine, and terbinafine) and morpholines (e.g., amorolfine); and antimetabolies (e.g., 5-fluorocytosine).

[0172] The present invention encompasses pharmaceutically acceptable salts, acids or derivatives of the agents (and members of the classes of agents) set forth above.

Dosing

[0173] The CD73 inhibitors of the present invention may be administered to a subject in an amount that is dependent upon, for example, the goal of administration (e.g., the degree of resolution desired); the age, weight, sex, and health and physical condition of the subject to which the formulation is being administered; the route of administration; and the nature of the disease, disorder, condition or symptom thereof. The dosing regimen may also take into consideration the existence, nature, and extent of any adverse effects associated with the agent(s) being administered. Effective dosage amounts and dosage regimens can readily be determined from, for example, safety and dose-escalation trials, in vivo studies (e.g., animal models), and other methods known to the skilled artisan.

[0174] In general, dosing parameters dictate that the dosage amount be less than an amount that could be irreversibly toxic to the subject (the maximum tolerated dose (MTD)) and not less than an amount required to produce a measurable effect on the subject. Such amounts are determined by, for example, the pharmacokinetic and pharmacodynamic parameters associated with ADME, taking into consideration the route of administration and other factors.

[0175] An effective dose (ED) is the dose or amount of an agent that produces a therapeutic response or desired effect in some fraction of the subjects taking it. The "median effective dose" or ED50 of an agent is the dose or amount of an agent that produces a therapeutic response or desired effect in 50% of the population to which it is administered. Although the ED50 is commonly used as a measure of reasonable expectance of an agent's effect, it is not necessarily the dose that a clinician might deem appropriate taking into consideration all relevant factors. Thus, in some situations the effective amount is more than the calculated ED50, in other situations the effective amount is less than the calculated ED50, and in still other situations the effective amount is the same as the calculated ED50.

[0176] In addition, an effective dose of the CD73 inhibitors of the present invention may be an amount that, when administered in one or more doses to a subject, produces a desired result relative to a healthy subject. For example, for a subject experiencing a particular disorder, an effective dose may be one that improves a diagnostic parameter, measure, marker and the like of that disorder by at least about 5%, at least about 10%, at least about 20%, at least about 25%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, or more than 90%, where 100% is defined as the diagnostic parameter, measure, marker and the like exhibited by a normal subject.

[0177] In certain embodiments, the CD73 inhibitors contemplated by the present invention may be administered (e.g., orally) at dosage levels of about 0.01 mg/kg to about 50 mg/kg, or about 1 mg/kg to about 25 mg/kg, of subject body weight per day, one or more times a day, to obtain the desired therapeutic effect.

[0178] For administration of an oral agent, the compositions can be provided in the form of tablets, capsules and the like containing from 1.0 to 1000 milligrams of the active ingredient, particularly 1.0, 3.0, 5.0, 10.0, 15.0, 20.0, 25.0, 50.0, 75.0, 100.0, 150.0, 200.0, 250.0, 300.0, 400.0, 500.0, 600.0, 750.0, 800.0, 900.0, and 1000.0 milligrams of the active ingredient.

[0179] In certain embodiments, the dosage of the desired CD73 inhibitor is contained in a "unit dosage form". The phrase "unit dosage form" refers to physically discrete units, each unit containing a predetermined amount of the CD73 inhibitor, either alone or in combination with one or more additional agents, sufficient to produce the desired effect. It will be appreciated that the parameters of a unit dosage form will depend on the particular agent and the effect to be achieved.

Kits

[0180] The present invention also contemplates kits comprising an CD73 inhibitor, and pharmaceutical compositions thereof. The kits are generally in the form of a physical structure housing various components, as described below, and may be utilized, for example, in practicing the methods described above.

[0181] A kit can include one or more of the CD73 inhibitors disclosed herein (provided in, e.g., a sterile container), which may be in the form of a pharmaceutical composition suitable for administration to a subject. The CD73 inhibitors can be provided in a form that is ready for use (e.g., a tablet or capsule) or in a form requiring, for example, reconstitution or dilution (e.g., a powder) prior to administration. When the CD73 inhibitors are in a form that needs to be reconstituted or diluted by a user, the kit may also include diluents (e.g., sterile water), buffers, pharmaceutically acceptable excipients, and the like, packaged with or separately from the CD73 inhibitors. When combination therapy is contemplated, the kit may contain the several agents separately or they may already be combined in the kit. Each component of the kit may be enclosed within an individual container, and all of the various containers may be within a single package. A kit of the present invention may be designed for conditions necessary to properly maintain the components housed therein (e.g., refrigeration or freezing).

[0182] A kit may contain a label or packaging insert including identifying information for the components therein and instructions for their use (e.g., dosing parameters, clinical pharmacology of the active ingredient(s), including mechanism of action, pharmacokinetics and

pharmacodynamics, adverse effects, contraindications, etc.). Labels or inserts can include manufacturer information such as lot numbers and expiration dates. The label or packaging insert may be, e.g., integrated into the physical structure housing the components, contained separately within the physical structure, or affixed to a component of the kit (e.g., an ampule, tube or vial).

[0183] Labels or inserts can additionally include, or be incorporated into, a computer readable medium, such as a disk (e.g., hard disk, card, memory disk), optical disk such as CD- or DVD- ROM/RAM, DVD, MP3, magnetic tape, or an electrical storage media such as RAM and ROM or hybrids of these such as magnetic/optical storage media, FLASH media or memory-type cards. In some embodiments, the actual instructions are not present in the kit, but means for obtaining the instructions from a remote source, e.g., via the internet, are provided.

EXPERIMENTAL

[0184] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the present invention, and are not intended to limit the scope of what the inventors regard as their invention, nor are they intended to represent that the experiments below were performed or that they are all of the experiments that may be performed. It is to be understood that exemplary descriptions written in the present tense were not necessarily performed, but rather that the descriptions can be performed to generate data and the like of a nature described therein. Efforts have been made to ensure accuracy with respect to numbers used (e.g., amounts, temperature, etc.), but some experimental errors and deviations should be accounted for. [0185] Unless indicated otherwise, parts are parts by weight, molecular weight is weight average molecular weight, temperature is in degrees Celsius (°C), and pressure is at or near atmospheric. Standard abbreviations are used, including the following: wt = wildtype; bp = base pair(s); kb = kilobase(s); nt = nucleotides(s); aa = amino acid(s); s or sec = second(s); min = minute(s); h or hr = hour(s); ng = nanogram; μg = microgram; mg = milligram; g = gram; kg = kilogram; dl or dL = deciliter; μΐ or μΐ ^ = microliter; ml or mL = milliliter; 1 or L = liter; μΜ = micromolar; mM = millimolar; M = molar; kDa = kilodalton; i.m. = intramuscular(ly); i.p. = intraperitoneal(ly); SC or SQ = subcutaneous(ly); QD = daily; BID = twice daily; QW = weekly; QM = monthly; HPLC = high performance liquid chromatography; BW = body weight; U = unit; ns = not statistically significant; PBS = phosphate-buffered saline; IHC =

immunohistochemistry; DMEM = Dulbeco's Modification of Eagle's Medium; EDTA = ethylenediaminetetraacetic acid.

[0186] LC: Agilent 1100 series; Mass spectrometer: Agilent G6120BA, single quad

LC-MS method: Agilent Zorbax Eclipse Plus C18 , 4.6 χ 100 mm, 3.5 μΜ, 35 °C, 1.5 mL/min flow rate, a 2.5 min gradient of 0% to 100% B with 0.5 min wash at 100% B; A = 0.1% of formic acid / 5% acetonitrile / 94.9% water; B = 0.1% of formic acid / 5% water / 94.9% acetonitrile

Flash column: ISCO Rf+

Reverse phase HPLC: ISCO-EZ; Column: Kinetex 5 μιη EVO C18 100 A; 250 χ 21.2 mm (Phenomenex)

Example 1

Synthesis of [({[(2R,3 J V,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin-9-y l]-3,4- dihydroxyoxolan-2-yl]methyl}carbamoyl)methyl]phosphonic acid

H 2 0

Step e

[0187] Step a: A mixture of 2,6-dichloro-9-(2,3,5-tri-0-acetyl-beta-D-ribofuranosyl)puri ne (13.5 g, 30 mmol), cyclopentylamine (3.2 mL, 33 mmol, 1.1 equiv.), and triethylamine (4.6 mL, 33 mmol, 1.1 equiv.) in MeOH (60 mL) was stirred at rt for overnight. 7M H 3 in MeOH (20 mL) was added and reaction was stirred at rt for 1 day. Reaction mixture was evaporated and the crude product was used in the next step without purification. ESI MS [M+H] + for

C15H21CIN5O4, calcd 370.1, found 370.2.

[0188] Step b: The product from Step a was dissolved in acetone (100 mL) and 2,2- dimethoxypropane (40 mL) and p-TsOH x H 2 0 (7.1 g, 37.5 mmol, 1.25 equiv.) was added. The reaction mixture was stirred at rt for overnight, then diluted with brine (100 mL) and carefully quenched with saturated NaHC0 3 (200 mL). After extraction with EtOAc (2 χ 200 mL), combined organics were dried over MgS0 4 , filtered and evaporated to give crude product that was used in the next step without purification (12.2 g, 98%). ESI MS [M+H] + for

C18H25CIN5O4, calcd 410.2, found 410.1. [0189] Step c: 1) Para-toluenesulfonyl chloride (1.68 g, 8.8 mmol) in pyridine (5 ml) was added dropwise to a solution of the product from Step b (3.0 g, 7.33 mmol) in pyridine (45 ml) at 0°C. The mixture was stirred at 0°C for 30 minutes then allowed to warm to room

temperature. After stirring overnight, the reaction was concentrated to dryness. The crude material obtained was reconstituted in ethyl acetate and washed with saturated NaHC0 3 and brine, dried over MgS0 4 and concentrated under reduced pressure. The desired tosylate (3.61 g. 87%) was obtained following column chromatography (S1O2, 10 to 60% gradient of EtOAc and hexane). ESI MS [M+H] + C^FLoClNsOeS for, calcd 564.2, found 564.2.

[0190] 2) To a solution of the above tosylate (1.0 g, 1.77 mmol) in DMF (8.85 mL) was added sodium azide (345 mg, 5.31 mmol). The resulting suspension was sealed and heated to 80°C overnight. After cooling to room temperature the reaction mixture was partitioned between ethyl acetate and water. The organic layer washed with water and brine, dried over MgS0 4 , and concentrated under reduced pressure. The title compound (548 mg) was used without further purification. ESI MS [M+H] + CisHzsClNsOs for, calcd 435.2, found 435.2. [0191] Step d: To a solution of the product from Step c (548 mg, 1.26 mmol) in THF (6.3 mL) and water (0.42 mL) at room temperature was added triphenylphosphine (992 mg, 3.78 mmol). After stirring overnight the reaction was diluted with ethyl acetate and washed with 1M NaOH, water, and brine. The organics were dried over MgS0 4 and concentrated under reduced pressure. The title compound was obtained following column chromatography (Si0 2 , 0 to 10% gradient of methanol and CH 2 C1 2 ). ESI MS [M+H] + CisHzsClNeOs for, calcd 409.2, found 409.2.

[0192] Step e: 1) To a solution of the product from Step d (1.26 mmol),

diethylphosphonoacetic and (1.51 mmol), and diisopropylethylamine (1.10 mL, 6.3 mmol) in DMF (6 mL) at room temperature was added HATU (574 mg, 1.51 mmol). The mixture was stirred for 1 hour then diluted with ethyl acetate and washed sequentially with 10% citric acid, sat. NaHCCb, water and brine. The organics were dried over MgS0 4 and concentrated under reduced pressure. The title compound (553 mg, 75%, two-steps) was obtained following column chromatography (Si0 2 , 0 to 10% gradient of methanol and CH 2 C1 2 ). ESI MS [M+H] +

C 24 H 36 C1N 6 07P for, calcd 587.2, found 587.3. [0193] 2) To a solution of the product above (540 mg, 0.921 mmol) in acetonitrile (5 mL) was added trimethylsilylbromide (1 ml). The reaction was stirred at room temperature for 3 hours the water (1 mL) was added and the reaction allowed to stir overnight. The reaction was

concentrated with a stream of nitrogen the diluted with water (3 ml) and purified directly by preparative HPLC (CI 8, gradient of acetonitrile and water with 0.1% TFA). ¾ NMR (400 MHz, DMSO-i&) δ 8.48 (d, J= 15.3 Hz, 1H), 8.35 (d, J= 7.5 Hz, 1H), 7.99 (t, J= 5.9 Hz, 1H), 5.79 (d, J= 6.2 Hz, 1H), 4.68 - 4.51 (m, 1H), 4.43 (q, J= 7.2 Hz, 1H), 4.07 (dd, J= 5.3, 3.4 Hz, 1H), 3.93 (td, J= 5.5, 3.3 Hz, 1H), 3.39 (dt, J= 14.4, 5.4 Hz, 2H), 2.75 - 2.55 (m, 2H), 2.15 - 1.83 (m, 2H), 1.78 - 1.44 (m, 6H). ESI MS [M+H] + C17H24CIN6O7P for, calcd 491.1, found 491.2.

Example 2

Synthesis of [({[(2R,3 J V,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin-9-y l]-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl]phospho nic acid

HO " 'OH Step b [0194] Step a: 1) To a solution of the product from step b from example 1 (6.29 g) in dichloroethane (125 mL) at 0 °C was added Dess-Martin periodinane (7.17 g, 16.9 mmol). The resulting suspension was allowed to warm to room temperature and stir overnight. The reaction was diluted with ethyl acetate and washed with 1M NaOH, water, and brine. The organic layer was dried over MgS0 4 and concentrated under reduced pressure. The crude material was used without further purification. ESI MS [M+H 2 0+H] + for CISHMCINSOS, calcd 426.2, found 426.3

[0195] 2) To a flask charged with crude aldehyde from the previous step was added

dichloroethane (150 mL). To the resulting solution was added methylamine (40wt% in water, 2.4 g, 30.6 mmol) followed by sodium triacetoxyborohydride (3.89 g, 18.4 mmol). The reaction was complete after two hours and parti oned between ethyl acetate and 1M NaOH. The organic layer was washed with water and brine, dried over MgS0 4 and concentrated under reduced pressure. Purification by column chromatography (Si0 2 , 0 to 15% gradient of methanol and CH 2 C1 2 ) provide the title compound (2.7g, 43%) as an off-white solid. ESI MS [M+H] + for

Ci9H 27 ClN 6 03, calcd 423.2, found 423.3. [0196] Step b: 1) To a solution of the product from Step a (146 mg, 0.345 mmol),

diethylphosphonoacetic acid (81 mg, 0.414 mmol) and diisopropylethylamine (0.30 mL, 1.73 mmol) in DMF (3.5 mL) at room temperature was added HATU (157 mg, 0.414 mmol). The mixture was stirred for 1 hour then diluted with ethyl acetate and washed sequentially with 10% citric acid, sat. NaHCC , water and brine. The organics were dried over MgS0 4 and concentrated under reduced pressure. The acetonide protected phosphono-acetamide (125 mg, 60%) was obtained following column chromatography (Si0 2 , 0 to 10% gradient of methanol and CH 2 C1 2 ). ESI MS [M+H] + C 25 H38C1N 6 0 7 P for, calcd 601.2, found 601.4.

[0197] 2) To a solution of the product above (125 mg) in acetonitrile (5 mL) was added trimethylsilylbromide (0.5 ml). The reaction was stirred at room temperature for 3 hours the water (0.5 mL) was added and the reaction allowed to stir overnight. The reaction was concentrated with a stream of nitrogen the diluted with water (5 ml) and purified directly by preparative HPLC (C18, gradient of acetonitrile and water with 0.1% TFA). ¾ NMR (400 MHz, DMSO-i&) δ 8.49 - 8.40 (m, 0.6H), 8.39 - 8.32 (m, 0.4H), 5.83 (d, 0.4H), 5.80 (d, J= 6.2 Hz, 0.6H), 5.28 - 4.93 (m, 0.4H), 4.67 - 4.57 (m, 1H), 4.56 - 4.34 (m, 1H), 4.18 - 4.00 (m, 2H), 3.90 - 3.70 (m, 1H), 3.51 - 3.38 (m, 1H), 3.05 (s, 2H), 3.02 - 2.82 (m, 1H), 2.80 (s, 1H), 1.94 (d, J = 8.8 Hz, 2H), 1.73 (d, J= 16.3 Hz, 3H), 1.66 - 1.44 (m, 4H). ESI MS [M-H] " CisHieClNeOvP for, calcd 503.1, found 503.1.

Example 3

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]meth l}(ethyl)carbamoyl)methyl]phosphonic acid

[0198] The title compound was obtained using identical procedure as for example 2, starting from ethylamine hydrochloride and triethylamine to give white solid: ¾ MR (mixture of rotamers, 400 MHz, DMSO-^) δ 8.50 - 8.29 (m, 2H), 5.91 - 5.69 (m, 1H), 5.04 (s, 0.5H), 4.71 (s, OH), 4.59 - 4.49 (m, OH), 4.43 (d, J= 7.6 Hz, 1H), 4.17 - 4.02 (m, 2H), 3.87 - 3.74 (m, 1H), 3.50 - 3.33 (m, 2H), 3.26 (dt, J= 15.0, 6.9 Hz, 1H), 2.94 - 2.62 (m, 2H), 1.93 (s, 2H), 1.72 (s, 3H), 1.68 - 1.43 (m, 5H), 1.05 (t, J= 7.0 Hz, 2H), 0.96 (t, J= 6.9 Hz, 2H). ESI MS [M-H] " for CwHisClNeOvP, calcd 517.1, found 517.2

Example 4

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]meth l}(2-hydroxyethyl)carbamoyl)methyl]phosphonic acid

[0199] The title compound was obtained using identical procedure as for example 2, starting from ethanolamine to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-i¾) δ 8.52 - 8.17 (m, 2H), 5.83 - 5.64 (m, 1H), 4.97 (s, 0.5H), 4.67 - 4.51 (m, 0.5H), 4.49 - 4.30 (m, 0.5H), 4.15 - 3.95 (m, 2H), 3.93 - 3.71 (m, 1H), 3.52 - 3.32 (m, 2H), 3.07 - 2.81 (m, 1H), 2.72 (d, 7= 21.1 Hz, 1H), 1.86 (s, 2H), 1.65 (s, 2H), 1.58 - 1.41 (m, 4H). ESI MS [M-H] " for CwHisClNeOsP, calcd 533.1, found 533.2

Example 5

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}(propan-2-yl)carbamoyl)methyl]ph osphonic acid

[0200] The title compound was obtained using identical procedure as for example 2, starting from isopropylamine to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-i¾) δ 8.43 (s, 1H), 8.38 - 8.30 (m, 1H), 5.84 (d, 7= 4.2 Hz, 0.5H), 5.78 (d, 7= 6.3 Hz, 0.5H), 4.79 - 4.68 (m, 0.5H), 4.51 - 4.35 (m, 1H), 4.30 - 4.08 (m, 3H), 3.99 (q, 7= 5.6 Hz, 0.5H), 3.74 (d, 7 = 5.6 Hz, 1H), 3.68 (dd, 7= 14.2, 4.8 Hz, 1H), 3.29 (dd, 7= 14.1, 6.8 Hz, 1H), 3.04 - 2.80 (m, 2H), 2.76 - 2.62 (m, 0.5H), 2.05 - 1.86 (m, 2H), 1.78 - 1.66 (m, 2H), 1.66 - 1.48 (m, 4H), 1.20 - 0.93 (m, 6H). ESI MS [M-H] " for CioHsoClNeOvP, calcd 531.2, found 531.2

Example 6

Synthesis of {[benzyl({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H -purin-9-yl]-3,4- dihydroxyoxolan-2-yl]methyl})carbamoyl]methyl}phosphonic acid

[0201] The title compound was obtained using identical procedure as for example 2, starting from benzylamine to give white solid: ¾ NMR (400 MHz, DMSO-d) δ 8.53 - 8.24 (m, 2H), 7.45 - 7.03 (m, 5H), 5.89 - 5.70 (m, 1H), 4.87 - 4.77 (m, 0.5H), 4.72 - 4.36 (m, 3H), 4.20 - 4.07 (m, 2H), 3.94 - 3.61 (m, 1H), 3.54 - 3.30 (m, 0.5H), 3.12 - 2.96 (m, 0.5H), 2.92 - 2.64 (m, 1H), 1.93 (s, 2H), 1.80 - 1.66 (m, 2H), 1.65 - 1.48 (m, 4H). ESI MS [M-H] " for C24H30CIN6O7P, calcd 579.2, found 579.3

Example 7

Synthesis of 2-(N-{[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-pur in-9-yl]-3,4- dihydroxyoxolan-2-yl] meth l}-2-phosphonoacetamido)acetic acid

[0202] The title compound was obtained using identical procedure as for example 2, starting from glycine tert-butyl ester hydrochloride to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-i&) δ 8.53 - 8.29 (m, 3H), 5.82 (d, J= 4.6 Hz, 0.5H), 5.78 (d, J= 6.5 Hz,

0.5H), 5.26 - 4.96 (m, 1H), 4.87 - 4.79 (m, 0.5H), 4.70 - 4.55 (m, 1H), 4.57 - 4.37 (m, 2H), 4.28 (br. s, 1H), 4.26 - 4.18 (m, 0.5H), 4.13 (s, 1H), 4.09 - 4.02 (m, 2H), 3.99 - 3.71 (m, 2H), 3.40 (dd, J= 14.3, 7.8 Hz, 1H), 3.11 - 2.64 (m, 3H), 2.06 - 1.84 (m, 2H), 1.72 (br. s, 2H), 1.63 - 1.48 (m, 4H). ESI MS [M-H] " for CigHieClNeOgP, calcd 547.1, found 547.2

Example 8 Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]meth l}(cyclopropylmethyl)carbamoyl)methyl]phosphonic acid

[0203] The title compound was obtained using identical procedure as for example 2, starting from cyclopropylmethylamine to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-i&) δ 8.40 (s, 0.5H), 8.34 - 8.23 (m, 1.5H), 5.81 (d, J= 4.1 Hz, 0.5H), 5.76 (d, J= 5.9 Hz, 0.5H), 4.70 - 4.58 (m, 1H), 4.52 - 4.35 (m, 1H), 4.19 - 4.02 (m, 2H), 3.93 - 3.75 (m, 1.5H), 3.48 (d, J= 10.4 Hz, 0.5H), 3.36 (dd, J= 15.5, 6.3 Hz, 0.5H), 3.28 - 3.15 (m, 1H), 3.08 (dd, J = 13.9, 6.7 Hz, 0.5H), 2.97 - 2.63 (m, 2H), 1.92 (br. s, 2H), 1.70 (br. s, 2H), 1.63 - 1.45 (m, 4H), 1.20 - 0.86 (m, 1H), 0.48 - 0.28 (m, 2H), 0.20 - 0.07 (m, 2H). ESI MS [M-H] " for

C21H30CIN6O7P, calcd 543.2, found 543.2

Example 9

Synthesis of [({[(2R,3S,4R,5R)-5-{2-chloro-6-[cyclopentyl(methyl)amino]-9 H-purin-9-yl}- 3,4-dihydroxyoxolan-2-yl]meth l}(cyclopropylmethyl)carbamoyl)methyl]phosphonic acid

[0204] The title compound was obtained using identical procedures as for example 1 and example 2, starting from cyclopropylmethylamine to give white solid: ¾ NMR (mixture or rotamers, 400 MHz, DMSO-d 6 ) δ 8.48 (s, 1H), 8.36 (s, 1H), 5.85 (d, J= 4.0 Hz, 1H), 5.80 (d, J = 5.9 Hz, 1H), 4.61 (dd, J= 5.9, 4.7 Hz, 0.5H), 4.46 (dd, J= 5.3, 4.0 Hz, 0.5H), 4.17 - 4.05 (m, 3H), 3.86 (td, J= 9.0, 8.3, 4.3 Hz, 2H), 3.54 (dd, J= 14.0, 6.9 Hz, 1H), 3.37 (dd, J= 15.3, 6.5 Hz, 1H), 3.30 - 3.20 (m, 2H), 3.12 (dd, J= 13.8, 6.7 Hz, 1H), 2.99 - 2.84 (m, 2H), 2.83 - 2.69 (m, 0.5H), 1.93 - 1.80 (m, 4H), 1.79 - 1.55 (m, 9H), 1.07 - 0.84 (m, 1H), 0.49 - 0.32 (m, 2H), 0.24 - 0.10 (m, 2H). ESI MS [M-H] " for C22H32CIN6O7P, calcd 557.2, found 557.2

Example 10

Synthesis of [({[(2R,3S,4R,5R)-5-{2-chloro-6-[cyclopentyl(methyl)amino]-9 H-purin-9-yl}- 3,4-dihydroxyoxolan-2-yl] meth l}(ethyl)carbamoyl)methyl] phosphonic acid

[0205] The title compound was obtained using identical procedures as for example 1 and example 2, starting from ethylamine hydrochloride to give white solid: ¾ MR (mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.50 (s, 1H), 8.37 (s, 1H), 5.86 (d, J= 4.4 Hz, 0.5H), 5.82 (d, J = 6.2 Hz, 1H), 4.65 (dd, J= 6.3, 4.6 Hz, 1H), 4.50 (t, J= 4.8 Hz, 0.5H), 4.11 (tt, J= 5.7, 2.8 Hz, 3H), 3.85 - 3.66 (m, 2H), 3.44 (dq, J= 14.6, 7.4 Hz, 3H), 3.34 - 3.20 (m, 1H), 2.94 - 2.66 (m, 3H), 1.92 - 1.57 (m, 2H), 1.80 - 1.54 (m, 9H), 1.06 (t, J= 7.1 Hz, 3H), 0.97 (t, J= 7.0 Hz, 2H). ESI MS [M-H] " for C20H30CIN6O7P, calcd 531.2, found 531.2

Example 11

Synthesis of [({[(2R,3S,4R,5R)-5-(2-chloro-6-{[(3S)-oxolan-3-yl]amino}-9H -purin-9-yl)-3,4- dihydroxyoxolan-2-yl]meth l}(methyl)carbamoyl)methyl]phosphonic acid

[0206] The title compound was obtained using identical procedure as for examples 1 and 2, starting from (,S)-2-aminotetrahydrofuran to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-i&) δ 8.61 - 8.43 (m, 1.6H), 8.38 (d, J= 1.3 Hz, 0.4H), 5.83 (d, J= 4.5 Hz, 0.4H), 5.81 - 5.77 (m, 0.6H), 4.61 (app s, 1.4H), 4.50 (s, 0.6H), 4.16 - 4.01 (m, 2H), 3.94 - 3.67 (m, 5H), 3.65 - 3.54 (m, 1H), 3.42 (s, 1H), 3.03 (s, 2H), 2.97 - 2.79 (m, 1H), 2.78 (s, 1H), 2.74 - 2.62 (m, 0.4H), 2.26 - 2.09 (m, 1H), 2.07 - 1.85 (m, 1H). ESI MS [M-H] " for Cn^ClNeOsP, calcd 505.1, found 505.3

Example 12

Synthesis of [({[(2R,3 J V,4R,5R)-5-[6-chloro-4-(cyclopentylamino)-lH-pyrazolo[ 3,4- d]pyrimidin-l-yl]-3,4-dihydroxyoxolan-2- yl]methyl}(methyl)carbamoyl)methyl]phosphonic acid

[0207] Step a: The nucleoside derivative (22 g, 49.3 mmol) was dissolved in MeOH (100 mL) and cooled to 0 °C. Cyclopentylamine (5. lg, 51.8 mmol, 1.05 equiv.), and triethylamine (7.2 mL, 51.8 mmol, 1.05 equiv.) were added and reaction mixture was stirred at 0 °C for 15 min then at rt for 4 h. 7M H 3 in MeOH (60 mL) was added and reaction was stirred at rt for 1 day. Reaction mixture was evaporated and the crude product was used in the next step without purification. ESI MS [M+H] + for C15H21CIN5O4, calcd 370.1, found 370.2

[0208] Step b: To a suspension of the product from Step a (4.2 g, 11.4 mmol) in acetone (20 mL) and 2,2-dimethoxypropane (20 mL), p-TsOH x H 2 0 (0.646 g, 3.4 mmol, 0.3 equiv.) was added. The reaction mixture was stirred at r.t for 30 min then evaporated. The residue was stirred with saturated NaHC0 3 (10 mL) and H 2 0 (50 mL). White solid was filtered off, washed with H 2 0 (2 30 mL) and dried under vacuum (4.2 g, 90%). ¾ MR (400 MHz, DMSO-^) δ 8.70 (d, J= 7.2 Hz, 1H), 8.24 (s, 1H), 6.18 (s, 1H), 5.28 (dd, J= 6.1, 1.8 Hz, 1H), 4.90 (dd, J = 6.2, 2.1 Hz, 1H), 4.85 (t, J= 5.8 Hz, 1H), 4.41 (q, J= 6.9 Hz, 1H), 4.16 - 4.06 (m, 1H), 3.51 - 3.40 (m, 1H), 3.38 - 3.30 (m, 1H), 2.04 - 1.92 (m, 2H), 1.79 - 1.52 (m, 6H), 1.50 (s, 3H), 1.31 (s, 3H). ESI MS [M+H] + for C18H25CIN5O4, calcd 410.2, found 410.2

[0209] Step c: An acetonide protected nucleoside (2 g, 4.9 mmol) was dissolved in CH2CI2 (50 mL) and cooled to 0 °C. Solid NaHC0 3 (412 mg, 4.9 mmol) was added followed by Dess- Martin periodinane (2.5 g, 5.9 mmol, 1.2 equiv.) and reaction mixture was stirred at r.t for lh (or until LCMS analysis shows no more starting material). Reaction mixture was quenched with saturated aqueous NaHC0 3 and organic layer was separated, dried over MgS0 4 , filtered and evaporated. Crude product was used in the next step without purification. ESI MS [M+H] + for Ci 8 H 23 ClN50 4 , calcd 408.1, found 408.2.

[0210] Step d: The product from Step c was dissolved in CH2CI2 (100 mL) and stirred with 40% aqueous solution of Me H 2 (4.2 mL, 49 mmol, 10 equiv.) at rt for 10 min. Na(OAc) 3 BH (2.1 g, 9.8 mmol, 2 equiv.) was added and reaction was stirred at rt for lh when the second portion of Na(OAc) 3 BH (2.1 g, 9.8 mmol, 2 equiv.) was added and stirred for additional 2.5h. Reaction mixture was quenched with saturated aqueous NaHC0 3 (50 mL) and organic layer was separated, dried over MgS0 4 , filtered and evaporated. Crude product was purified by column chromatography (Si0 2 , Hex→100% EtOAc) to give yellow solid (540 mg, 26%). ESI MS

[M+H] + for Ci9H 28 ClN 6 03, calcd 423.2, found 423.3.

[0211] Step e: To the mixture of: product from Step d (530 mg, 1.25 mmol),

diethylphosphonoacetic acid (247 mg, 1.25 mmol) and DIPEA (263 μΐ., 1.5 mmol, 1.2 equiv.) in anhydrous DMF (8 mL) solid HATU (574 mg, 1.5 mmol, 1.2 equiv.) was added. Reaction mixture was stirred at rt for lh then diluted with H 2 0 (30 mL) and extracted with MTBE (3 x 10 mL). Combined organics were dried over MgS0 4 , filtered and evaporated to give crude product that was used in the next step without purification. ESI MS [M+H] + for C 2 5H3 C1N 6 07P, calcd 601.2, found 601.1. [0212] Step f: The crude product from Step e (330 mg, 0.55 mmol) was dissolved in anhydrous CH3CN (5 mL), TMS-Br (0.5 mL) was added and reaction was stirred at rt for overnight. Quenched with H 2 0 (1 mL) and stirred at rt for 4 h, or until LCMS analysis shows complete cleavage of the acetonide protecting group. The reaction mixture was evaporated and purified by reverse phase HPLC (C I 8 column, 0 to 30% gradient of acetonitrile and water with 0.1% TFA) to give the product as a white solid in 41% yield (140 mg): ¾ MR (400 MHz,

DMSO^) δ 8.76 - 8.61 (m, 1H), 8.32 - 8.18 (m, 1H), 6.05 - 5.95 (m, 1H), 4.64 - 4.52 (m, 1H), 4.48 - 4.32 (m, 2H), 4.32 - 4.20 (m, 1H), 4.20 - 4.12 (m, 1H), 4.12 - 3.98 (m, 2H), 3.98 - 3.86 (m, 1H), 3.81 - 3.69 (m, 1H), 3.66 - 3.55 (m, 1H), 3.16 - 2.67 (m, 4H), 2.04 - 1.91 (m, 2H), 1.78 - 1.45 (m, 6H). ESI MS [M+H] + for calcd 505.1, found 505.3.

Example 13

Synthesis of [({[(2R,3S,4R,5R)-5-[6-chloro-4-(cyclopentylamino)-lH-pyrazo lo[3,4- d] pyrimidin- 1-yl] -3,4-dihydroxyoxolan-2-yl] methyl} (cyclopropylmethyl)- carbamoyl)methyl]phosphonic acid

[0213] The title compound was obtained using identical procedure as for example 12, starting from cyclopropylmethylamine to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-i&) δ 8.73 - 8.60 (m, 1H), 8.27 - 8.14 (m, 1H), 6.10 - 5.83 (m, 1H), 4.59 (dd, J= 5.1, 4.7 Hz, 0.5H), 4.40 (d, J= 6.3 Hz, 0.5H), 4.36 - 4.31 (m, 0.5H), 4.30 - 4.21 (m, 0.5H), 4.20 - 4.13 (m, 0.5H), 4.12 - 4.05 (m, 1H), 4.00 (d, J= 13.8 Hz, 0.5H), 3.74 (m, 1H), 3.50 (d, J= 15.7 Hz, 1H), 3.24 - 3.04 (m, 2H), 2.99 - 2.87 (m, 1H), 2.87 - 2.70 (m, 0.5H), 2.62 - 2.53 (m, 0.5H), 2.08 - 1.86 (m, 2H), 1.71 (br. s, 2H), 1.64 - 1.47 (m, 4H), 0.93 - 0.78 (m, 1H), 0.48 - 0.26 (m, 2H), 0.25 - 0.01 (m, 2H). ESI MS [M-H] " for CiiHsoClNeOvP, calcd 543.2, found 543.2

Example 14

Synthesis of [({[(2R,3R,4 J V,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin-9-yl]- 4- fluoro-3-hydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl] phosphonic acid

[0214] Step a: 2,6-dichloropurine (3.6 g, 18.8 mmol) was dissolved in 90 mL of acetonitrile and treated with CS2CO3 (7.5 g, 23 mmol, 1.2 equiv.). The mixture was stirred at room temperature for 30 min. The known bromo derivative (8.75 g, 21 mmol, 1.1 equiv.) was dissolved in 100 mL of acetonitrile and added to the mixture dropwise via an addition funnel. The mixture was allowed to stir overnight at room temperature. The mixture was filtered on a pad of silica gel and concentrated. The residue was adsorbed on silica and purified using column chromatography (hexanes / ethyl acetate) to provide the product as a white solid in 77% yield (7.72g). ¾ NMR (400 MHz, Chloroform-ύ δ 8.39 (d, J= 3.0 Hz, 1H), 8.10 (ddt, J= 8.5, 3.1, 0.9 Hz, 4H), 7.74 - 7.36 (m, 6H), 6.64 (dd, J = 21.8, 2.8 Hz, 1H), 5.83 - 5.69 (m, 1H), 5.40 (ddd, J = 49.9, 2.8, 0.8 Hz, 1H), 4.89 - 4.77 (m, 2H), 4.62 (q, J = 4.0 Hz, 1H). ESI MS [M+H] + for C24H17CI2FN4O5, calcd 531.1, found 531.1 [0215] Step b: 1) The dichloride from Step a (0.75 g, 1.4 mmol), cyclopentyl amine (0.2 mL, 2.1 mmol, 1.5 equiv.), and Et 3 N (0.4 mL, 2.8 mmol, 2.0 equiv.) in anhydrous EtOH (5 mL) was stirred at 70 °C for 4 hours. The reaction mixture was then cooled to room temperature and the product was collected by filtration and used without further purification (white solid, 0.69 g, 73%). ESI MS [M+H] + for C29H28CIFN5O5, calcd 580.2, found 580.3.

[0216] 2) The product from above (0.68 g, 1 mmol) and K 2 C0 3 (0.4 g, 3 mmol, 3 equiv) were dissolved in 10 mL of methanol and stirred at room temperature for 4 hours. The reaction mixture was then filtered and concentrated on a pad of silica gel. The reaction mixture was purified using column chromatography (methylene chloride / methanol) to provide the product as a white solid. (88%, 0.33 g) ESI MS [M+H] + for Ci5H 2 oClFN 5 0 3 , calcd 372.1, found 372.3.

[0217] Step c: 1) A solution of the diol from the above step (875 mg; 2.35 mmol) and imidazole (456 mg, 6.70 mmol) in DCM (12 mL) was cooled to 0 °C and TBSC1 (674 mg, 4.47 mmol) was added as a solid in one portion. The mixture was warmed to r.t. and stirred for 1 hour. The solvent was removed and the residue purified by silica gel chromatography (0 to 30% EtOAc in hexanes) to afford the desired product as a white solid (946 mg; 83%).

[0218] 2) A solution of the product from the above step (987 mg, 2.03 mmol), ?- toluenesulfonic acid monohydrate (34 mg; 0.203 mmol) in 3,4-dihydro-2H-pyran (4 mL) and THF (20 mL) was stirred at r.t. for 14 h. The reaction was quenched with triethylamine, the solvent was evaporated, and the residue was passed through a plug of silica gel (EtOAc). [0219] 3) The residue was redissolved in THF (17 mL), cooled to 0 °C, and TBAF (2.05 mL, 1.0 M solution in THF) was added dropwise. The mixture was stirred at 0 °C for 30 minutes. The solvent was evaporated and the residue purified by silica gel chromatography (0-5% MeOH in DCM) to afford the desired product as a colorless oil (742 mg, 80%). ESI MS [M+H] + for C20H27CIFN5O4, calcd 456.2, found 456.3. [0220] Step d: 1) To a solution of the product from step c (470 mg, 1.03 mmol) in

dichloroethane (10 mL) at 0°C was added Dess-Martin periodinane (522 mg, 1.27 mmol). The resulting suspension was allowed to warm to room temperature and stir overnight. The reaction was diluted with ethyl acetate and washed with 1M NaOH, water and brine, dried over MgS0 4 and concentrated under reduced pressure. The crude material was used directly in the following step.

[0221] 2) To a flask charged with crude aldehyde was added dichloroethane (5 mL). To the resulting solution was added methylamine (40wt% in water, 400 mg, 5.15 mmol) followed by sodium triacetoxyborohydride (262 mg, 1.24 mmol). The reaction was complete after six hours and partioned between ethyl acetate and water. The organic layer was washed with brine, dried over MgS0 4 and concentrated under reduced pressure. Purification by column chromatography (S1O2, 5 to 20% gradient of methanol and CH2CI2) provide the title compound (75 mg, 11%) as an off-white solid. ESI MS [M+H] + for C21H30CIFN6O3, calcd 469.2, found 469.3. [0222] Step e: 1) To a solution of the product from Step d (75 mg, 0.16 mmol),

diethylphosphonoacetic acid (38 mg, 0.19 mmol) and diisopropylethylamine (84 μί, 0.48 mmol) in DMF (2 mL) at room temperature was added HATU (72 mg, 0.19 mmol). The mixture was stirred for 1 hour then diluted with ethyl acetate and washed sequentially with 10% citric acid, sat. NaHCCb, water and brine. The organics were dried over MgS0 4 and concentrated under reduced pressure. The resulting phosphono-acetamide was used without further purification.

[0223] 2) To a solution of the product above in acetonitrile (2.5 mL) was added

trimethylsilylbromide (0.25 ml). The reaction was stirred at room temperature for 3 hours the water (0.25 mL) was added and the reaction allowed to stir overnight. The reaction was concentrated with a stream of nitrogen the diluted with water (5 ml) and purified directly by preparative HPLC (C18, gradient of acetonitrile and water with 0.1% TFA). ¾ NMR (mixture of rotamers, 400 MHz, DMSO-^) δ 8.36 - 8.28 (m, 1H), 8.24 - 8.19 (m, 1H), 8.15 (d, J= 2.4 Hz, OH), 6.34 - 6.14 (m, 1H), 5.21 - 5.07 (m, 1H), 5.04 - 4.86 (m, 1H), 4.42 - 4.22 (m, 2H), 4.04 - 3.88 (m, 1H), 3.83 - 3.60 (m, 1H), 3.58 - 3.44 (m, 1H), 3.03 (s, 2H), 2.97 - 2.60 (m, 3H), 1.86 (d, J= 8.1 Hz, 2H), 1.68 - 1.58 (m, 2H), 1.58 - 1.41 (m, 5H). ESI MS [M-H] " for

Ci8H 2 5ClFN60 6 P, calcd 505.1, found 505.1.

Example 15

Synthesis of 2-({[(2S)-l-oxo-l-(propan-2-yloxy)propan-2-yl]amino}(phenoxy )phosphoryl) acetic acid

Step a

[0224] Step a: To a solution of [2-(benzyloxy)-2-oxoethyl]phosphonic acid (17.5 mmol) in pyridine (100 mL) was added phenol (6.33 g, 67.22 mmol), H-Ala-OiPr-HCl (4.39 g, 26.19 mmol) and triethylamine (27 mL, 192 mmol). To this suspension was added via cannula a freshly prepared solution of triphenylphosphine (15.6 g, 59.3 mmol) and aldrithiol (13.5 g, 61.1 mmol) in pyridine (100 ml). The reaction was heated to 60°C overnight. After cooling to room temperature diluted with ethyl acetate and washed sequentially with 10% citric acid, sat.

NaHC0 3 , water and brine. The organics were dried over MgS0 4 and concentrated under reduced pressure. The desired product (2.21 g, 30%) was obtained following two chromatographic separations (S1O2, gradient of EtOAc and hexane, followed by Si0 2 , 0 to 10% gradient of methanol and CH 2 C1 2) . ESI MS [M+H] + for C 2 iH 26 N0 6 P, calcd 420.2, found 420.2

[0225] Step b: To a solution of the product from step a (2.21 g, 5.27 mmol) in ethanol (50 mL) under a nitrogen atmosphere was added Pd/C (10wt% wet, 250 mg). The nitrogen atmosphere was displaced with hydrogen and reaction stirred at room temperature. In 1 hour increments 250 mg Pd/C was added up to 750 mg total, each time displacing the hydrogen with nitrogen before addition and subsequently sparging the reaction with hydrogen. After 5 hours the reaction was diluted with ethyl acetate and filtered through a pad of celite and concentrated under reduced pressure to afford the title compound (1.50 g, 86%) which was greater than 90% purity as judged by ¾ MR and used without further purification. ¾ MR (Mixture of diastereomers, 400 MHz, DMSO-i&) δ 7.35 (ddd, J= 8.6, 7.5, 3.7 Hz, 2H), 7.22 - 7.12 (m, 3H), 5.63 (ddd, J= 23.0, 12.5, 9.9 Hz, 1H), 4.84 (dp, J= 7.5, 6.2 Hz, 1H), 3.94 - 3.81 (m, 1H), 3.08 (dd, J= 5.9, 2.4 Hz, 1H), 3.03 (dd, J = 6.1, 2.4 Hz, 1H), 1.25 - 1.10 (m, 9H). ESI MS [M+H] + for Ci 4 H 20 NO 6 P, calcd 330.1, found 330.2 Example 16

Synthesis of propan-2-yl (2S)-2-({[({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino) purin-9-yl]-3,4-dihydroxyoxolan-2-yl]methyl}(methyl)carbamoy l)methyl](phenoxy)- phosphor l}amino)propanoate

[0226] Step a: The product of Step a from example 2 (500 mg, 1.18 mmol) was dissolved in acetonitrile (5 mL) and 6N HC1 (1 mL) was added. The reaction was stirred at room temperature overnight then diluted with acetonitrile (20 ml) and concentrated to dryness under reduced pressure to provide the desired amine-hydrochloride which was used directly in the proceeding reaction. ESI MS [M+H] + for CieHzsClNeOs, calcd 383.2, found 383.3.

[0227] Step b: To a screw-top vial charged with the product from step a (1.18 mmol) was added DMF (6 mL) followed by the Protide phosphoramidate from example 15 (388 mg, 1.18 mmol) and diisopropylethylamine (617 μί, 3.54 mmol). HATU (448 mg, 1.18 mmol) was subsequently added and the mixture was stirred for 1 hour then diluted with ethyl acetate and washed sequentially with 10% citric acid, sat. NaHC0 3 , water and brine. The organics were dried over MgS0 4 and concentrated under reduced pressure. The desired product (206 mg, 25%) was obtained by column chromatography (S1O2, 0 to 10% gradient of methanol and CH 2 C1 2 ). ¾ MR (Mixture of diastereomers androtamers, 400 MHz, DMSO-de) δ 8.47 (s, 1H), 8.42 - 8 (m, 2H), 7.39 - 7.25 (m, 3H), 7.18 - 7.03 (m, 4H), 5.83 (dd, J= 11.2, 5.4 Hz, 2H), 5.63 (d, J 5.6 Hz, OH), 5.56 - 5.24 (m, 4H), 4.88 - 4.75 (m, 1H), 4.72 - 4.58 (m, 1H), 4.57 - 4.47 (m, OH), 4.48 - 4.36 (m, 1H), 4.24 - 4.05 (m, 3H), 3.94 - 3.68 (m, 3H), 3.59 - 3.42 (m, 1H), 3.34 (s, 2H), 3.31 - 3.12 (m, 3H), 3.05 (s, 3H), 2.89 - 2.79 (m, 1H), 1.96 (d, J= 27.9 Hz, 3H), 1.78 - 1.65 (m, 3H), 1.63 - 1.47 (m, 6H), 1.24 - 1.01 (m, 14H). ESI MS [M+H] + for C30H41CIN7O8P, calcd 694.2, found 694.4

Example 17

Synthesis of methyl (2S)-2-({[({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)

9-yl]-3,4-dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)meth yl](phenoxy)- phosphoryl}amino)propanoate

[0228] The title compound was obtained using identical procedures as for example 16 to give white solid: ¾ NMR (mixture of diastereomers and rotamers, 400 MHz, DMSO-de) δ 8.46 - 8.40 (m, 0.6H), 8.36 - 8.34 (m, 0.3H), 8.33 - 8.26 (m, 1.2H), 7.35 - 7.24 (m, 2H), 7.15 - 7.02 (m, 3H), 5.81 (dd, J = 13.7, 5.2 Hz, 1H), 5.66 - 5.38 (m, 2H), 5.35 (app d, J= 6.1 Hz, 0.4H), 5.28 (dd, J= 8.6, 4.6 Hz, 0.7H), 4.69 - 4.56 (m, 0.6H), 4.56 - 4.47 (m, 0.4H), 4.47 - 4.33 (m, 0.6H), 4.22 - 4.01 (m, 2H), 4.00 - 3.65 (m, 2H), 3.57 - 3.46 (m, 3H), 3.27 - 3.12 (m, 2H), 3.03 (s, 2H), 2.89 - 2.75 (m, 1H), 2.01 - 1.81 (m, 2H), 1.76 - 1.63 (m, 2H), 1.63 - 1.43 (m, 4H), 1.18 (d, J= 7.1 Hz, 1H), 1.13 (d, J= 7.0 Hz, 1.2H), 1.08 (d, J = 7.0 Hz, 0.5H). ESI MS [M+H] + for CisHsvClNvOsP, calcd 666.2, found 666.3 Example 18

Synthesis of propan-2-yl (2S)-2-({[({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)- 9H- purin-9-yl]-3,4-dihydroxyoxolan-2-yl]methyl}(methyl)carbamoy l)methyl]({[(2S)-l-oxo-l- (propan-2-yloxy)propan-2-yl]amino})phosphoryl}amino)propanoa te

[0229] Step a: To a solution of [2-(benzyloxy)-2-oxoethyl]phosphonic acid (17.5 mmol) in pyridine (90 mL) was added H-Ala-OiPr*HCl (11.7 g, 69.84 mmol) and triethylamine (24 mL, 175 mmol). To this suspension was added via cannula a freshly prepared solution of

triphenylphosphine (14.1 g, 69.84 mmol) and aldrithiol (15.4 g, 69.8 mmol) in pyridine (90 ml). The reaction was heated to 60°C for 6 hours. After cooling to room temperature the reaction was diluted with ethyl acetate and washed sequentially with 10% citric acid, sat. NaHC0 3 , water and brine. The organics were dried over MgS0 4 and concentrated under reduced pressure. The desired product was purified by column chromatography (S1O2, 0 to 15% gradient of methanol and CH 2 C1 2 >. Fraction containing the desired amidate were repurified by reverse phase chromatography (CI 8, gradient of MeCN and H 2 0 containing 0.1% formic acid). ESI MS

[M+H] + for C 2 iH 33 N 2 0vP, calcd 457.2, found 457.3.

[0230] Step b: To a solution of the product from step a (47 mg, .103 mmol) in ethanol (2 mL) under a nitrogen atmosphere was added Pd/C (10wt% wet, 50 mg). The nitrogen atmosphere was displaced with hydrogen and reaction stirred at room temperature. After 5 hours the reaction was diluted with ethyl acetate and filtered through a pad of celite and concentrated under reduced pressure to afford the title compound (38 mg) which was used without further purification. ESI MS [M+H] + for C14H27N2O7P, calcd 367.2, found 367.3. [0231] Step c: To a screw-top vial charged with the product from example 16 step a (0.15 mmol) was added DMF (2 mL) followed by the bis-phosphoramidate from step b (0.10 mmol) and diisopropylethylamine (90 μΐ,, 0.515 mmol). HATU (47 mg, 0.124 mmol) was subsequently added and the mixture was stirred for 1 hour then diluted with ethyl acetate and washed sequentially with 10% citric acid, sat. NaHCCb, water and brine. The organics were dried over MgS0 4 and concentrated under reduced pressure. The desired product (42 mg, 57%) was obtained by column chromatography (S1O2, gradient of ethyl acetate and hexane. ¾ MR (mixture of diastereomers and rotamers, 400 MHz, DMSO-<f 6 ) δ 8.49 (s, 0.6H), 8.43 - 8.31 (m, 1.3H), 5.84 (d, J= 4.3 Hz, 0.4H), 5.80 (d, J= 6.1 Hz, 0.6H), 5.12 - 4.97 (m, 0.6H), 4.93 - 4.80 (m, 2H), 4.69 - 4.38 (m, 5H), 4.23 - 4.02 (m, 3H), 3.89 - 3.70 (m, 4H), 3.61 - 3.42 (m, 1H), 3.10 - 2.75 (m, 5H), 1.92 (s, 2H), 1.74 - 1.66 (m, 3H), 1.66 - 1.48 (m, 4H), 1.34 - 1.10 (m, 18H). ESI MS [M+H] + for calcd 731.3, found 731.4.

Example 19

Synthesis of propan-2-yl (2S)-2-({[({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)- 9H- purin-9-yl]-4-hydroxy-3-[(2-methylpropanoyl)oxy]oxolan-2- yl]meth l}(methyl)carbamoyl)methyl](phenoxy)phosphoryl}amino)propano ate

[0232] To a solution of example 16 (250 mg, 0.36 mmol) in pyridine (3.6 mL) at 0 °C was added isobutyryl chloride (38 μί, 0.36 mmol) dropwise via syringe. The reaction was allowed to warm to room temperature and stir for two hours. The reaction was concentrated under reduced pressure and resulting residue was reconstituted in ethyl acetate and washed sequentially with saturated sodium bicarbonate, water and brine. The organics were dried over magnesium sulfate and concentrated to dryness. The crude product was purified by column chromatography (CI 8, gradient of MeCN and H 2 0 containing 0.1% formic acid) to provide the title compound (166 mg, 60%) as a white powder following lyophilization. ¾ NMR (mixture of diastereomers and rotamers, 400 MHz, DMSO-^) δ 8.49 - 8.32 (m, 2H), 7.35 - 7.20 (m, 2H), 7.18 - 6.98 (m, 3H), 6.17 - 6.01 (m, 1H), 5.90 - 5.80 (m, 1H), 5.59 - 5.43 (m, 1.5H), 5.36 (t, J= 10.9 Hz, 0.5H), 4.88 - 4.68 (m, 1H), 4.45 - 4.35 (m, 1H), 4.35 - 4.27 (m, 0.5H), 4.04 - 3.76 (m, 3H), 3.62 (dd, J = 14.1, 7.2 Hz, 0.5H), 3.30 (s, 3H), 3.25 - 3.12 (m, 2H), 3.09 - 2.98 (m, 2H), 2.67 - 2.51 (m,

1.5H), 1.91 (s, 2H), 1.69 (s, 2H), 1.64 - 1.45 (m, 5H), 1.21 - 0.87 (m, 20H). ESI MS [M+H] + for C34H47CIN7O9P, calcd 764.3, found 764.4

Example 20

Synthesis of 7V-{[(2R,3 J V,4R,5R)-5-[2-chloro-6-(cyclopentylamino)- 9H-purin-9-yl]-3,4- dihydroxyoxolan-2-yl] methyl} -2- [4-(3-chlorophenyl)-2-oxo-l,3^ 5 - dioxaphosphinan- 2-yl]-7V-methylacetamide

[0233] Step a: To the acetonide (example 2, step bl, 545 mg, 1.00 mmol), and DMF (20 μΐ in dichloromethane (5 mL) was added oxalyl chloride (186 μΐ., 2.20 mmol) dropwise at r.t. The reaction mixture was heated at 45 °C for 90 minutes. The reaction was then concentrated. To the residue was added Et 3 N (418 μΐ ^ , 3.00 mmol) and dichloromethane (5 mL), the mixture cooled to -20 °C, and a solution of l-(3-chlorophenyl)-l,3-propanediol (187 mg, 1.00 mmol) in

dichloromethane (5 mL) was added dropwise. The reaction mixture was stirred at -20 °C for 30 minutes, warmed to r.t., and stirred for an additional 1 hour. The solvent was evaporated and the residue purified by silica gel chromatography (0-5% MeOH in dichloromethane) to afford the desired product as a yellow solid (241 mg, 35%). [0234] Step b: A solution of the product from step a (241 mg, 0.346 mmol) in TFA/H2O (6.9 mL, 1 : 1 ratio) was stirred at r.t. for 1 hour. The solvent was evaporated and the residue purified directly by reverse phase HPLC (CI 8 column, 0 to 60% gradient of acetonitrile and water with 0.1%) TFA) to afford the desired product as a white solid (170 mg, 75%, 3 :2 mixture of P-C diastereomers). ¾ MR (400 MHz, DMSO-d 6 ) δ 8.51 - 8.29 (m, 2H), 7.55 - 7.29 (m, 4H), 5.88 - 5.57 (m, 2H), 4.70 - 4.02 (m, 6H), 3.96 - 3.65 (m, 1H), 3.58 - 3.25 (m, 2H), 3.09 (s, 1H), 3.04 (d, J= 6.5 Hz, 1H), 2.84 (s, 1H), 2.20 - 1.84 (m, 4H), 1.63 (d, J= 63.1 Hz, 6H). ESI MS [M+H] + for CivHMChNeOvP, calcd 655.2, found 655.2.

Example 21

Synthesis of diphenyl [({[(2R,35',4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin -9- yl]-3,4-dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl ]phosphonate

[0235] The title compound was synthesized in similar fashion to example 20 using 2 equivalent of phenol): ¾ NMR (1 : 1 mixture of rotamers ,400 MHz, DMSO-<f 6 ) δ 8.42 - 8.40 (m, 1H), 8.35 (t, J= 8.8 Hz, 1H), 7.43 - 7.26 (m, 4H), 7.26 - 7.13 (m, 4H), 7.13 - 7.00 (m, 1H), 5.87 - 5.82 (m, 1H), 4.67 - 4.24 (m, 4H), 4.18 - 4.05 (m, 2H), 3.68 - 3.58 (m, 2H), 3.72 - 3.37 (m, 3H), 3.07 (s, 1.5H), 2.86 (s, 1.5H), 2.05 - 1.41 (m, 8H). ESI MS [M+H] + for

C30H34CIN6O7P, calcd 656.2, found 657.3.

Example 22

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl](phenox y)phosphinic acid

[0236] The title compound was synthesized in similar fashion to example 20, using 1 equivalent of phenol): ¾ NMR (2: 1 mixture of rotamers, 400 MHz, DMSO-<f 6 ) δ 8.32 - 8.24 (m, 2H), 7.29 - 7.21 (m, 4H), 5.82 - 5.80 (m, 2H), 5.10 - 3.37 (m, 6H), 3.20 - 2.98 (m, 2H), 1.92 - 1.85 (m, 2H), 1.67 - 1.42 (m, 6H). ESI MS [M-H] " for C24H30CIN6O7P, calcd 579.2, found 579.3.

Example 23

Synthesis of N-{[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)- 9H-purin-9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}-N- methyl-2-(2-oxo-2,4-dihydro-l,3^ 5 - benzodioxa hosphinin-2- l)acetamide

[0237] The phosphonyl chloride (230 mg, 0.39 mmol) was dissolved in anhydrous CH2CI2 (5 mL) and cooled to 0 °C. Solid 2-(hydroxymethyl)phenol (72 mg, 0.58 mmol, 1.5 equiv.) was added followed by triethylamine (217 μΐ., 1.56 mmol, 4 equiv.). Reaction was stirred at 0 °C for lh, then quenched with trifluoroacetic acid (3 mL) and stirred at rt for 5 h. The reaction mixture was evaporated and purified by reverse phase HPLC (CI 8 column, 0 to 40% gradient of acetonitrile and water with 0.1% TFA) to give the product as a white solid in 11% yield (32 mg): 1 H MR (400 MHz, OMSO-d 6 ) δ 8.42 (d, J= 2.4 Hz, 1H), 8.40 - 8.31 (m, 1H), 7.39 - 6.97 (m, 4H), 5.86 - 5.75 (m, 1H), 5.55 - 5.23 (m, 3H), 4.66 - 4.38 (m, 2H), 4.25 - 3.98 (m, 2H), 3.90 - 3.60 (m, 2H), 3.57 - 3.23 (m, 6H), 2.04 - 1.85 (m, 2H), 1.79 - 1.45 (m, 6H). ESI MS [M+H] + for C25H31CIN6O7P, calcd 593.2, found 593.3

Example 24

Synthesis of N-{[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)- 9H-purin-9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}-N- methyl-2-(2-oxo-2,4-dihydro-lH-3,l^ 5 - benzoxazaphosphinin-2-yl)acetamide

[0238] 1) To a solution of the product from example 20-Step al (250 mg, 0.43 mmol) and diisopropylethylamine (374 μί, 2.15 mmol) in dichloromethane (8.6 mL) was added 2- aminobenzyl alcohol (106 mg, 0.86 mmol) in a single portion. The reaction was stirred overnight the concentrated to dryness. The resulting residue was used directly in the next step. ESI MS [M+H] + for C28H35CIN7O6P, calcd 632.2, found 632.3.

[0239] 2) To a screw-top vial containing the product from the above step was added 90% v/v TFA/H2O. The mixture was stirred for 15 minutes the partitioned between ethyl acetate and saturated NaHCCb. The organics were washed with brine, dried over MgS0 4 and concentrated under reduced pressure. The crude product was reconstituted in DMSO (2mL) and the title compound was isolated following preparative HPLC (CI 8, gradient of MeCN and H2O containing 0.1% formic acid). ¾ NMR (mixture of diastereomers and rotamers, 400 MHz,

DMSO-i&) δ 8.53 - 8.29 (m, 3H), 7.27 - 7.09 (m, 2H), 6.93 - 6.79 (m, 2H), 5.85 - 5.73 (m, 1H), 5.62 (d, J= 5.7 Hz, 0.5H), 5.49 (d, J= 6.1 Hz, 0.5H), 5.38 (dd, J= 5.9, 2.8 Hz, 0.5H), 5.29 (dd, J = 5.8, 4.8 Hz, 0.5H), 5.24 - 4.96 (m, 2H), 4.68 - 4.50 (m, 1H), 4.49 - 4.35 (m, 0.5H), 4.18 - 3.95 (m, 2H), 3.77 - 3.63 (m, 1H), 3.26 - 3.07 (m, 2H), 3.08 - 2.91 (m, 2H), 2.05 - 1.86 (m, 3H), 1.78 - 1.66 (m, 2H), 1.66 - 1.48 (m, 3H). ESI MS [M+H] + for CisHsiClNvOeP, calcd 592.2, found 592.2.

Example 25

Synthesis of N-{[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)- 9H-purin-9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}-N- methyl-2-(8-methyl-2-oxo-2,4-dihydro-lH- 3,1,2λ 5 - benzoxazaphosphinin-2-yl)acetamide

[0240] The title compound was obtained using identical procedures as for example 24, from 3- methyl-2-aminobenzyl alcohol to give white solid: ¾ NMR (mixture of diastereomers and rotamers, 400 MHz, DMSO-^) δ 8.45 - 8.27 (m, 2H), 7.86 - 7.68 (m, 1H), 7.15 - 6.92 (m, 2H), 6.88 - 6.75 (m, 1H), 5.85 - 5.73 (m, 1H), 5.48 (d, J= 6.2 Hz, 0.5H), 5.37 (d, J= 5.8 Hz, 0.5H), 5.28 (dd, J= 9.7, 4.8 Hz, 0.5H), 5.14 - 4.95 (m, 2H), 4.65 - 4.36 (m, 1H), 4.25 - 3.86 (m, 1H), 3.78 - 3.56 (m, 1H), 3.22 - 2.84 (m, 3H), 2.28 - 2.11 (m, 3H), 2.02 - 1.84 (m, 2H), 1.79 - 1.65 (m, 2H), 1.65 - 1.47 (m, 4H). ESI MS [M+H] + for CieHssClNvOeP, calcd 606.2, found 606.3 Example 26

Synthesis of bis({[(propan-2-yloxy)carbonyl]oxy}methyl) ({[(2R,3»V,4R,5R)-5-[2-chloro-

6-(cyclopentylamino)-9H-purin-9-yl]-3,4-dihydroxyoxolan-2 - yl]methyl}(methyl)carbamoyl)methanephosphonate

[0241] Step a: The acetonide (example 2, step bl, 500 mg, 0.92 mmol) was placed under nitrogen and dissolved in 2 mL anhydrous DMF. To the resulting solution was added

chloromethyl isopropyl carbonate (1.3 mL, 9.2 mmol, 10 equiv.) followed by N,N- diisopropylethylamine (1.6 mL, 9.2 mmol, 15 equiv.). The mixture was heated to 60 °C for 9 hours. After cooling to room temperature the mixture was concentrated under reduced pressure and the crude residue was purified by reverse phase flash chromatography (CI 8 column, 0 to 100% gradient of acetonitrile and water with 0.1% formic acid) to give the mono alkylated product as a white solid (26a, 90 mg, 15%) and the bis alkylated product as a white solid (26b, 220 mg, 31%).

[0242] Step b: 26b from Step a (220 mg) was dissolved in 4 mL of 90% TF A/water at 0 °C. After stirring at ambient temperature for 15 minutes, the mixture was concentrated under reduced pressure and the crude residue was purified by reverse phase flash chromatography (CI 8 column, 0 to 100%) gradient of acetonitrile and water with 0.1%> formic acid) to provide the product as a white solid ¾ MR (400 MHz, DMSO^) δ δ 8.42 (s, 0.6H), 8.37 - 8.33 (m, 1.4H), 5.83 (dd, J = 13.0, 5.4 Hz, 1H), 5.68 - 5.48 (m, 4H), 5.36 (dd, J= 13.0, 5.3 Hz, 1H), 4.89 - 4.76 (m, 2H), 4.64 (d, J= 5.7 Hz, 0.8H), 4.55 (d, J= 5.5 Hz, 0.6H), 4.43 (d, J= 7.4 Hz, 0.8H), 4.16 (d, J= 5.3 Hz, 0.5H), 4.07 (dt, J= 7.2, 3.8 Hz, 2H), 3.86 - 3.62 (m, 2H), 3.49 - 3.37 (m, 2H), 2.98 (s, 2H), 2.82 (s, 1H), 1.92 (s, 2H), 1.71 (s, 2H), 1.55 (d, J= 8.5 Hz, 5H), 1.24 (dt, J= 6.2, 1.2 Hz, 13H). ESI MS [M+H] + for C28H43C1N6013P, calcd 737.2, found 737.3.

Example 27

Synthesis of [({[(2R,3 J V,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin-9-y l]-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl]({[(pro pan-2- yloxy)carbonyl]oxy}methoxy)phosphinic acid

[0243] The title compound was synthesized in similar fashion to example 26 from compound 26a: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-d) δ δ 8.42 (s, 0.6H), 8.34 (d, J = 1.2 Hz, 0.4H), 8.31 (d, J= 7.8 Hz, 0.8H), 5.82 (d, J= 4.4 Hz, 0.3H), 5.78 (d, J= 6.0 Hz, 1H), 5.46 (t, J= 11.1 Hz, 0.8H), 5.02 (s, 0.5H), 4.84 - 4.70 (m, 1H), 4.60 (s, 0.4H), 4.49 (s, 1H), 4.41 (d, J = 8.8 Hz, 1.5H), 4.14 (s, 1.3H), 4.06 (s, 2H), 3.73 (s, 1.5H), 3.44 (s, 1.3H), 2.98 (d, J= 23.1 Hz, 2H), 2.78 (s, 1H), 1.91 (s, 2H), 1.70 (s, 2H), 1.54 (s, 4H), 1.21 (dt, J= 6.3, 1.1 Hz, 7H). ESI MS [M+H] + for C23H35CIN6O10P, calcd 621.2, found 621.3.

Example 28

Synthesis of 6 s[(ethoxycarbonyl)oxy] methyl ({[(2R,3S,4R,5R)-5-[2-chloro-6-

(cyclopentylamino)-9H-purin-9-yl]-3,4-dihydroxyoxolan-2-y l]methyl}(methyl)carbamoyl)- methanephosphonate

[0244] The title compound was synthesized in similar fashion to example 26: ¾ NMR

(mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.40 (d, J= 1.2 Hz, 1H), 8.40 - 8.26 (m, 1H), 5.90 - 5.73 (m, 1H), 5.69 - 5.43 (m, 4H), 5.43 - 5.26 (m, 1H), 5.01 (s, 0.5H), 4.61 (s, 0.6H), 4.52 (s, 0.4H), 4.41 (d, J= 7.4 Hz, 0.7H), 4.24 - 4.11 (m, 4H), 4.05 (d, J= 7.3 Hz, 1H), 3.84 - 3.58 (m, 1H), 3.50 - 3.33 (m, 2H), 2.96 (s, 2H), 2.80 (s, 1H), 1.91 (s, 2H), 1.69 (s, 2H), 1.64 - 1.47 (m, 4H), 1.26 - 1.16 (m, 6H). ESI MS [M+H] + for CieHsgClNeOisP, calcd 709.2, found 709.3.

Example 29

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2yl]methyl}(methyl)carbamoyl)methyl]({[(etho xycarbonyl)oxy]methoxy}) phosphinic acid

[0245] The title compound was synthesized in similar fashion to example 27: ¾ NMR

(mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.53 - 8.12 (m, 2H), 6.52 (s, 0.4H), 5.77 (d, J = 25.6 Hz, 1H), 5.51 - 5.30 (m, 1H), 5.18 (s, 0.4H), 4.49 (d, J= 56.9 Hz, 1H), 4.24 - 4.00 (m, 3H), 2.90 (d, J= 134.9 Hz, 2H), 2.62 (d, J= 21.2 Hz, 1H), 1.91 (s, 2H), 1.69 (s, 2H), 1.54 (s, 4H), 1.19 (td, J = 7.1, 3.6 Hz, 3H). ESI MS [M+H] + for C22H33CIN6O10P, calcd 607.2, found 607.3

Example 30

Synthesis of 6 s[(methoxycarbonyl)oxy] methyl ({[(2R,3S,4R,5R)-5-[2-chloro-6- (cyclopentylamino)-9H-purin-9-yl]-3,4-dihydroxyoxolan-2-yl]m ethyl}(methyl)carbamoyl)- methanephosphonate

[0246] The title compound was obtained using identical procedures as for example 26 to give white solid: 'HNMR (Mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.45 - 8.22 (m, 2 H), 5.83 (dd, J = 12.7, 5.3 Hz, 1 H), 5.66 - 5.46 (m, 5 H), 5.34 (d, J= 13.4 Hz, 1 H), 4.73 - 4.37 (m, 2 H), 4.20 - 4.00 (m, 2 H), 3.77 (t, J= 2.6 Hz, 6 H), 3.52 - 3.35 (m, 2 H), 3.05 - 2.73 (m, 3 H), 2.05 - 1.84 (m, 2 H), 1.75 - 1.43 (m, 6 H). ESI MS [M+H] + for C24H35CIN6O13P, calcd 681.2, found 681.3

Example 31

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl]({[(met hoxycarbonyl)- oxy]methoxy})phosphinic acid

[0247] The title compound was obtained using identical procedures as for example 27 to give white solid: 'H NMR (mixture of rotamers, 400 MHz, DMSO- 6 ) δ 8.45 (s, 1 H), 8.39 - 8.29 (m, 1 H), 5.86 - 5.77 (m, 1 H), 5.54 - 5.44 (m, 3 H), 4.70 - 4.37 (m, 2 H), 4.20 - 4.05 (m, 2 H), 3.74 (s, 3H), 3.34 (s, 3 H, masked by HDO), 3.07 - 2.77 (m, 3 H), 1.96 - 1.91 (m, 2 H), 1.78 - 1.45 (m, 6 H). ESI MS [M+H] + for C 2 IH 3 IC1N 6 OIOP, calcd 593.2, found 593.3

Example 32

Synthesis of fos({[(2,2-dimethylpropoxy)carbonyl]oxy}methyl) ({[(2R,3S,4R,5R)-5-[2- chloro-6-(cyclopentylamino)-9H-purin-9-yl]-3,4-dihydroxyoxol an-2- yl]methyl}(methyl)carbamo l)methanephosphonate

[0248] The title compound was obtained using identical procedures as for example 26 to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.41 - 8.36 (m, 0.6H), 8.36 - 8.33 (m, 0.4H), 8.30 (app d, J= 7.7 Hz, 1H), 5.87 - 5.76 (m, 1H), 5.64 - 5.45 (m, 6H), 5.33 (dd, J= 5.9, 1.6 Hz, 0.4H), 5.30 (dd, J= 4.8, 1.6 Hz, 0.6H), 4.67 - 4.48 (m, 1H), 4.46 - 4.36 (m, 0.6H), 4.18 - 3.99 (m, 2H), 3.90 - 3.59 (m, 6H), 3.51 - 3.32 (m, 2H), 2.96 (s, 2H), 2.80 (s, 1H), 2.08 - 1.81 (m, 2H), 1.78 - 1.64 (m, 2H), 1.64 - 1.47 (m, 4H), 0.92 - 0.85 (m, 18H). ESI MS [M+H] + for FORMULA, calcd 793.3, found 793.4

Example 33

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl]({[(2,2 -dimethylpropoxy)- carbonyl]oxy}methox hosphinic acid

[0249] The title compound was obtained using identical procedures as for example 27 to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.45 - 8.24 (m, 2H), 5.82 (d, J= 4.5 Hz, 0.4H), 5.79 (d, J= 6.2 Hz, 0.6H), 5.58 - 5.39 (m, 2H), 4.69 - 4.32 (m, 2H), 4.18 - 3.97 (m, 2H), 3.84 - 3.66 (m, 3H), 3.55 - 3.32 (m, 1H), 3.16 - 2.71 (m, 5H), 2.08 - 1.80 (m, 2H), 1.73 - 1.64 (m, 2H), 1.62 - 1.47 (m, 5H). ESI MS [M+H] + for CisHssClNeOioP, calcd

649.2, found 649.3

Example 34

Synthesis of fa ' s({[(2-methoxyethoxy)carbonyl]oxy}methyl) ({[(2R,3S,4R,5R)-5-[2-chloro-6- (cyclopentylamino)-9H-purin-9-yl]-3,4-dihydroxyoxolan-2-yl]m ethyl}(methyl)carbamoyl)- methanephosphonate

[0250] The title compound was obtained using identical procedures as for example 26 to give white solid: ¾ MR (mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.45 - 8.19 (m, 2 H), 5.87 - 5.68 (m, 1 H), 5.68 - 5.26 (m, 5 H), 4.69 - 4.35 (m, 2 H), 4.31 - 3.96 (m, 5 H), 3.87 - 3.59 (m, 1 H), 3.59 - 3.50 (m, 3 H), 3.49 - 3.19 (m, 5 H), 3.00 - 2.73 (m, 3 H), 2.04 - 1.84 (m, 2 H), 1.80 - 1.65 (m, 2 H), 1.65 - 1.46 (m, 4 H). ESI MS [M+H] + for CisifcClNeOisP, calcd 769.2, found 769.3

Example 35

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl]({[(2-m ethoxyethoxy)carbonyl]- oxy}methoxy)phosphinic acid

[0251] The title compound was obtained using identical procedures as for example 27 to give white solid: 'HNMR (Mixture of rotamers, 400 MHz, DMSO- 6 ) δ 8.53 - 8.23 (m, 2 H), 5.82 (dd, J = 15.0, 5.2 Hz, 1 H), 5.50 (t, J= 10.6 Hz, 3 H), 4.66 - 4.36 (m, 1 H), 4.24 (tt, J= 4.0, 2.4 Hz, 1 H), 4.08 (s, 1 H), 3.76 (s, 1 H), 3.58 - 3.50 (m, 6 H, masked by HDO), 3.25 (s, 3 H), 3.06 - 2.77 (m, 3 H), 2.07 - 1.84 (m, 2 H), 1.79 - 1.44 (m, 6 H). ESI MS [M+H] + for CisHssClNeOnP, calcd 637.2, found 637.3

Example 36 Synthesis of ({[({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-puri n-9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl]({[(2,2 -dimethylpropanoyl)oxy]- methoxy})phosphoryl}oxy)methyl 2,2-dimethylpropanoate

[0252] The title compound was synthesized in similar fashion to example 26: ¾ NMR

(mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.43 (s, 1H), 8.35 (d, J= 8.6 Hz, 1H), 7.95 (s, 0.3H), 5.82 (dd, J= 11.6, 5.3 Hz, 1H), 5.58 (td, J= 14.2, 13.7, 5.6 Hz, 4H), 5.36 (dd, J= 11.5, 5.3 Hz, 1H), 5.05 (s, 0.4H), 4.64 (s, 0.7H), 4.53 (s, 0.4H), 4.47 - 4.37 (m, 1H), 4.16 (s, 0.4H), 4.13 - 4.01 (m, 1H), 3.91 - 3.61 (m, 1H), 2.98 (s, 2H), 2.89 (d, J= 0.5 Hz, 1H), 2.82 (s, 1H), 2.77 - 2.68 (m, 1H), 1.92 (s, 2H), 1.71 (s, 2H), 1.56 (s, 4H), 1.15 (d, J= 8.2 Hz, 18H). ESI MS [M+H] + for C30H47CIN6O11P, calcd 733.3, found 733.3.

Example 37

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl]({[(2,2 -dimethylpropanoyl)oxy]- methoxy})phosphinic acid

[0253] The title compound was synthesized in similar fashion to example 27: ¾ NMR

(mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.43 (s, 0.4H), 8.34 (s, 0.4H), 8.30 (d, J= 7.5 Hz, 1H), 5.91 - 5.69 (m, 1H), 5.62 - 5.31 (m, 2H), 5.02 (s, 0.6H), 4.60 (s, 0.6H), 4.41 (s, 1H), 4.10 (d, J= 31.6 Hz, 2H), 3.78 (d, J= 17.6 Hz, 1H), 3.02 (s, 2H), 2.94 (d, J= 20.8 Hz, 1H), 2.79 (s, 1H), 1.92 (s, 3H), 1.70 (s, 2H), 1.54 (s, 4H), 1.19 - 1.05 (m, 8H). ESI MS [M+H] + for

C24H37CIN6O9P, calcd 619.2, found 619.3.

Example 38

Synthesis of fa ' s({[(propan-2-yloxy)carbonyl]oxy}methyl) ({[(2R,3S,4R,5R)-5-[2-chloro-6- (cyclopentylamino)-9H-purin-9-yl]-3,4-dihydroxyoxolan-2-yl]m ethyl}(cyclopropylmethyl)- carbamoyl)methanephos honate

[0254] The title compound was obtained using identical procedures as for example 26 to give white solid: ¾ NMR (Mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.47 - 8.18 (m, 2H), 5.86 - 5.73 (m, 1H), 5.62 - 5.43 (m, 6H), 5.33 (dd, J= 6.1, 2.3 Hz, 0.4H), 5.27 (dd, J= 4.9, 2.3 Hz, 0.6H), 4.85 - 4.73 (m, 2H), 4.68 (br s, 0.6H), 4.57 - 4.32 (m, 1.4H), 4.21 - 4.02 (m, 2H), 3.96 - 3.67 (m, 2H), 3.53 - 3.34 (m, 2H), 3.26 - 3.01 (m, 2H), 2.04 - 1.82 (m, 2H), 1.76 - 1.64 (m, 2H), 1.64 - 1.45 (m, 5H), 1.27 - 1.17 (m, 12H), 1.03 - 0.89 (m, 1H), 0.38 (h, J= 5.1 Hz, 2H), 0.16 (dt, J= 12.5, 8.4 Hz, 2H). ESI MS [M+H] + for CsifteClNeOisP, calcd 777.3, found 777.4

Example 39

Synthesis of [({[(2R,3S,4R,5R)-5-[2-chloro-6-(cyclopentylamino)-9H-purin- 9-yl]-3,4- dihydroxyoxolan-2-yl]methyl}(cyclopropylmethyl)carbamoyl)met hyl]({[(propan-2- yloxy)carbonyl]oxy}methox hosphinic acid

[0255] The title compound was obtained using identical procedures as for example 27 to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.40 (s, 0.6H), 8.35 - 8.27 (m, 1.4H), 5.81 (d, J= 4.0 Hz, 0.4H), 5.76 (d, J= 6.0 Hz, 0.6H), 5.51 - 5.37 (m, 2H), 4.81 - 4.71 (m, 1H), 4.71 - 4.58 (m, 0.4H), 4.51 - 4.35 (m, 1.6H), 4.21 - 4.01 (m, 2.4H), 3.90 - 3.76 (m, 2.6H), 3.22 - 2.74 (m, 4H), 2.02 - 1.82 (m, 2H), 1.76 - 1.63 (m, 2H), 1.64 - 1.44 (m, 4H), 1.25 - 1.16 (m, 6H), 1.05 - 0.84 (m, 1H), 0.45 - 0.30 (m, 2H), 0.23 - 0.07 (m, 2H). ESI MS [M+H] + for CieHssClNeOioP, calcd 661.2, found 661.3 Example 40

Synthesis of bis({[(propan-2-yloxy)carbonyl]oxy}methyl) ({[(2R,3S,4R,5R)-5-(2-chloro-6-

{[(3S)-oxolan-3-yl]amino}-9H-purin-9-yl)-3,4-dihydroxyoxo lan-2- yl]methyl}(methyl)carbamo l)methanephosphonate

[0256] The title compound was obtained using identical procedures as for example 26 to give white solid: ¾ NMR (Mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.61 - 8.28 (m, 2H), 5.82 (app dd, J = 12.0, 5.0 Hz, 1H), 5.66 - 5.43 (m, 5H), 5.37 - 5.27 (m, 1H), 4.86 - 4.73 (m, 2H), 4.57 (d, J= 35.6 Hz, 2H), 4.19 - 3.99 (m, 2H), 3.95 - 3.64 (m, 4H), 3.64 - 3.55 (m, 1H), 3.50 3.34 (m, 2H), 2.96 (s, 2H), 2.80 (s, 1H), 2.18 (br s, 1H), 2.08 - 1.84 (m, 1H), 1.27 - 1.17 (m, 12H). ESI MS [M+H] + for C27H40CIN6O14P, calcd 739.2, found 739.3

Example 41

Synthesis of [({[(2R,3S,4R,5R)-5-(2-chloro-6-{[(3S)-oxolan-3-yl]amino}-9H -purin-9-yl)-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl]({[(pro pan-2- yloxy)carbonyl]oxy}methox hosphinic acid

[0257] The title compound was obtained using identical procedures as for example 27 to give white solid: ¾ NMR (Mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.60 - 8.46 (m, 1.6H), 8.41 (s, 0.4H), 5.82 (d, 7 = 4.1 Hz, 0.4H), 5.76 (d, 7= 5.9 Hz, 0.6H), 5.43 - 5.31 (m, 1.6H), 5.31 - 5.13 (m, 0.4H), 4.80 - 4.71 (m, 0.6H), 4.68 - 4.42 (m, 1.4H), 4.15 - 4.00 (m, 1H), 3.94 - 3.79 (m, 2H), 3.75 - 3.64 (m, 2H), 3.63 - 3.56 (m, 1H), 3.10 - 2.97 (m, 4H), 2.77 - 2.63 (m, 4H), 2.27 - 2.09 (m, 1H), 2.07 - 1.80 (m, 1H), 1.26 - 1.09 (m, 6H). ESI MS [M+H] + for

C22H32CIN6O11P, calcd 623.2, found 623.3

Example 42

Synthesis of 6i ' s({[(2-methoxyethoxy)carbonyl]oxy}methyl) ({[(2R,3S,4R,5R)-5-(2-chloro-6- {[(3S)-oxolan-3-yl]amino}-9H-purin-9-yl)-3,4-dihydroxyoxolan -2- yl]methyl}(methyl)carbamoyl)methanephosphonate

[0258] The title compound was obtained using identical procedures as for example 26 to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.59 - 8.33 (m, 2H), 5.84 (d, 7= 4.6 Hz, 0.4H), 5.81 (d, 7= 6.1 Hz, 0.6H), 5.65 - 5.45 (m, 5H), 5.34 (d, 7= 5.9 Hz, 0.4H), 5.33 - 5.28 (m, 0.6H), 4.67 - 4.48 (m, 2H), 4.28 - 4.20 (m, 4H), 4.18 - 3.99 (m, 2H), 3.93 - 3.64 (m, 4H), 3.60 (dd, 7 = 8.7, 4.5 Hz, 1H), 3.56 - 3.48 (m, 4H), 3.48 - 3.34 (m, 2H), 3.34 - 3.26 (m, 4H), 3.26 - 3.18 (m, 5H), 2.96 (s, 2H), 2.80 (s, 1H), 2.29 - 2.09 (m, 1H), 2.08 - 1.82 (m, 1H). ESI MS [M+H] + for C27H40CIN6O16P, calcd 771.2, found 771.3 Example 43

Synthesis of fos[(ethoxycarbonyl)oxy] methyl ({[(2R,3S,4R,5R 5-(2-chloro-6-{[(3S)-oxolan-3- yl]amino}-9H-purin-9-yl)-3,4-dihydroxyoxolan-2- yl]methyl}(methyl)carbamoyl)methanephosphonate

[0259] The title compound was obtained using identical procedures as for example 26 to give white solid: ESI MS [M+H] + for calcd 711.2, found 711.3

Example 44

Synthesis of [({[(2R,3S,4R,5R)-5-(2-chloro-6-{[(3S)-oxolan-3-yl]amino}-9H -purin-9-yl)-3,4- dihydroxyoxolan-2yl]methyl}(methyl)carbamoyl)methyl]({[(etho xycarbonyl)oxy]methoxy}) phosphinic acid

[0260] The title compound was obtained using identical procedures as for example 27 to give white solid: ¾ MR (400 MHz, DMSO^) δ 8.59 - 8.45 (m, 1.6H), 8.40 (s, 0.4H), 5.83 (d, J = 4.4 Hz, 0.4H), 5.79 (d, J= 6.1 Hz, 0.6H), 5.51 - 5.41 (m, 3H), 4.61 (br s, 1.6H), 4.50 (br s, 0.4H), 4.18 - 4.09 (m, 2.4H), 4.09 - 4.02 (m, 1.6H), 3.94 - 3.81 (m, 2H), 3.81 - 3.67 (m, 1H), 3.62 - 3.56 (m, 1H), 3.49 - 3.38 (m, 1H), 3.02 (s, 2H), 2.99 - 2.81 (m, 2H), 2.78 (s, 1H), 2.26 - 2.10 (m, 1H), 2.07 - 1.86 (m, 1H), 1.28 - 1.10 (m, 3H). ESI MS [M+H] + for CiiHsoClNeOnP, calcd 609.1, found 609.3

Example 45

Synthesis of fos({[(2,2-dimethylpropoxy)carbonyl]oxy}methyl) ({[(2R,3S,4R,5R)-5-(2- chloro-6-{[(3S)-oxolan-3-yl]amino}-9H-purin-9-yl)-3,4-dihydr oxyoxolan-2- yl]methyl}(methyl)carbamo l)methanephosphonate

[0261] The title compound was obtained using identical procedures as for example 26 to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.56 (s, 1H), 8.44 (d, J= 1.1 Hz, 0.6H), 8.39 (d, J= 1.1 Hz, 0.3H), 5.83 (d, J= 4.4 Hz, 0.4H), 5.80 (d, J= 6.1 Hz, 0.6H), 5.63 - 5.49 (m, 5H), 5.36 (dd, J= 5.9, 1.1 Hz, 0.4H), 5.33 (dd, J= 4.9, 1.1 Hz, 0.6H), 4.67 - 4.48 (m, 2H), 4.18 - 3.98 (m, 1H), 3.94 - 3.54 (m, 10H), 3.49 - 3.34 (m, 2H), 2.96 (s, 2H), 2.80 (s, 1H), 2.26 - 2.08 (m, 1H), 2.07 - 1.84 (m, 1H), 0.88 (s, 21H). ESI MS [M+H] + for

calcd 795.3, found 795.5

Example 46

Synthesis of [({[(2R,3S,4R,5R)-5-(2-chloro-6-{[(3S)-oxolan-3-yl]amino}-9H -purin-9-yl)-3,4- dihydroxyoxolan-2-yl]methyl}(methyl)carbamoyl)methyl]({[(2,2 - dimethylpropoxy)carbon l]oxy}methoxy)phosphinic acid

[0262] The title compound was obtained using identical procedures as for example 27 to give white solid: ¾ NMR (mixture of rotamers, 400 MHz, DMSO-d 6 ) δ 8.60 - 8.46 (m, 1.6H), 8.40 (s, 0.4H), 5.82 (d, J = 4.4 Hz, 0.4H), 5.81 - 5.75 (m, 0.6H), 5.51 - 5.36 (m, 2H), 4.69 - 4.42 (m, 2H), 4.17 - 3.97 (m, 1H), 3.94 - 3.66 (m, 6H), 3.59 (dd, J= 8.9, 4.7 Hz, 1H), 3.43 (dd, J= 13.8, 7.1 Hz, 0.4H), 3.12 - 2.65 (m, 6H), 2.28 - 2.10 (m, 1H), 2.06 - 1.85 (m, 1H), 0.87 (s, 9H). ESI MS [M+H] + for C24H36CIN6O11P, calcd 651.2, found 651.3

TABLE 1

STRUCTURE Example Potency

Table 1: Specific Examples (Potency: CD73 IC50: + means > 1 μΜ, ++ means 100 nM to 1 μΜ, +++ means < 100 nM).