Pharmaceutically Active Lipid-Based Formulation of Nucleoside-Lipid Conjugates

Inventors: Jia-Ai Zhang, Sydney Ugwu, Lan Ma, Moghis U Ahmad, Shoukath M AIi, Abdul R Khan,

Imran Ahmad

Field of the Invention

The present invention relates to novel formulations of nucleoside-lipid conjugates, the methods of preparing them and the methods for administering them. More particularly, the present invention relates to methods for making liposomal formulations of nucleoside-cardiolipin and analogues thereof.

Background of the Invention

Nucleoside analogues are compounds which mimic naturally occurring nucleosides by participating in nucleic acid metabolism. With this capability, nucleoside analogues are known to be clinically useful therapeutic agents. To date, several nucleoside analogues have been developed for the treatment of cancer and viral infections.

One example of a nucleoside analogue is a dideoxynucleoside analogue. Examples of dideoxynucleoside analogues include potent agents used for the treatment of AIDS such as 3'-Azido- 3'deoxythymidine (AZT) (See Mitsuya et al. Proc. Natl. Acad. Sci. U.S.A., 82, 7096-7100 (1985)), dideoxyinosine (ddl), dideoxycytidine (ddC) (See Mitsuya and Border, Proc. Natl. Acad. Sci. U.S.A., 83, 1911-1915 (1986)), 2'3'-didehydro~2'dideoxythymidine (d4T) and 3'-azido-2',3'-dideoxyuridine (AZddU). See Balzarini et al., MoI. Pharmacol., 32, 162-167 (1987). Serious toxicity, however, was noted with AZT as indicated by the anemia and granulocytopenia associated with its administration. See Fischl et al., New Eng. J. Med., 317, 185-191 (1987); See also Richman et al, New Eng. J. Med., 317, 192-197 (1987).

Another example of a nucleoside analogue is cytarabine (1-β-D-arabinofuranosylcytosine, ara-C). Used for the treatment of hematological malignancies, cytarabine interferes with the growth of cancer cells. Upon entering the cells, cytarabine is phosphorylated to triphosphates (araCTP) by deoxycytidine kinases (dCK). The active form of cytarabine, araCTP, then inhibits DNA polymerase by replacing deoxycytidine triphosphate (dCTP) with araCTP. See Damaraju et al., Oncogene, 22, 7524-7536 (2003). Although effective, the compound has a short half-life due to the deamination and dephosphorylation of its active form to its inactive form by cytidine deaminase and cytoplasmic 5 '-nucleotidase respectively.

Fludarabine (9-β-D-arabinofuranosyl-2-fluoroadenine) is another example of a nucleoside analogue. Used to treat low-grade lymphomas and chronic lymphocytic leukemia, fludarabine is a purine nucleoside analog that is administered as a 5 '-monophosphate (F-araAMP). See Chun et al., J. Clin. Oncol., 9, 175-188 (1991). Before entering cells, F-araAMP is dephosphorylated by plasma phosphatases and ecto-5'-nucleotidases to fludarabine (F-araA). Once dephosphorylated, F-araA is then transmitted to cells by nucleoside transporters (NTs). Like other nucleoside analogues, fludarabine is initially phosphorylated by dCK to its monophosphate (fludara, F-araAMP) form and then further phosphorylated to its triphosphate (F-araATP) form. The active form, F-araATP, then inhibits several enzymes involved in nucleoside synthesis and DNA replication. In noncycling cells, other F-araATP mechanisms include incorporation into RNA resulting in premature chain termination and impairment of cellular protein synthesis. See Damaraju et al, Oncogene, 22, 7524-7536 (2003).

Another example of a nucleoside analogue is cladribine (2-chloro-2'-deoxyadenosine, 2-CdA). Similar to fludarabine, cladribine is used to treat low-grade lymphomas and chronic lymphocytic leukemia. Cladribine differs from fludarabine, however, with chlorine substituted for fluorine at the 2-position of the adenine moiety. See Damaraju et al, Oncogene, 22, 7524-7536 (2003).

Capecitabine (5'-deoxy-5-N-[(pentoxy)carbonyl]cytidine), a prodrug of 5'-fluorouracil, is another example of a nucleoside analogue. After oral administration, capecitabine is metabolized by carboxyesterases to 5'-deoxy-5-fluorocytidine and then deaminated by cytidine deaminase to 5'deoxy-5- fluorouridine. As a metabolite of capecitabine, 5'-deoxy-5-fluorouridine monophosphate inhibits thymidylate synthase and is incorporated into DNA as 5'-deoxy-5-fluorouridine triphosphate. The last activation step is catalyzed by thymidine phosphorylase, which converts 5'-deoxy-5-fluorouridine into 5- flurouracil. Unlike other 5-fluorouracil treatments, capecitabine has shown activity in metastatic colorectal cancer. See Damaraju et al, Oncogene, 22, 7524-7536 (2003).

Another example of a nucleoside analogue is gemcitabine. Currently marketed as Gemzar ^® , gemcitabine (2',2'-difluorodeoxyribofuranosylcytosine) is a difluorinated analogue of deoxycytidine that is used for the treatment of non-small cell lung cancer, colon cancer and pancreatic cancer. Once administered, gemcitabine is rapidly activated from its inactive form to its active form of diphosphate (dFdCDP) and triphosphate (dFdCTP) nucleosides. Upon activation, gemcitabine exhibits cell phase specificity by targeting cells undergoing DNA synthesis (S-phase) and cells progressing through the Gl/S- phase boundary. See Physicians ' Desk Reference, 56 ^th Edition. The cytotoxicity of gemcitabine results from the actions of gemcitabine diphosphate and gemcitabine triphosphate. Firstly, gemcitabine diphosphate reduces the concentrations of deoxynucleoside triphosphates for DNA synthesis by inhibiting ribonucleotide reductase (a necessary enzyme for deoxynucleotide synthesis). By reducing the amount of

deoxynucleoside triphosphates, specifically dCTP, gemcitabine diphosphate allows for self-potentiation by facilitating the incorporation of gemcitabine triphosphate. As a result, gemcitabine triphosphate can successfully compete with dCTP for incorporation into DNA. Once incorporated, DNA polymerase epsilon is unable to remove the gemcitabine nucleotide. As a result, only one additional nucleotide is added to the growing DNA strands resulting in the inhibition of DNA synthesis and the promotion of cell apoptosis.

Although promising in many respects, the use of gemcitabine and other nucleoside analogues remains hindered by their short plasma half-life. For example, once administered, deoxycytidine deaminase rapidly deaminates gemcitabine to its inactive form of 2'2'-difluorodeoxyuridine (dFdU). See Myhren et ah, US Patent No. 6,384,019 Bl; See also Johnson, P.G. et ah, Cancer Chromatography and Biological Response Modifiers, Annual 16, Chap. 1, ed. Pinedo et al. (1996). As a result, many nucleoside analogues must be administered at high levels (e.g. gemcitabine at 1000 mg/m ² with a 30-minute intravenous infusion) in order to achieve therapeutic drug levels. Levels exceeding these amounts, however, produce significant toxic side effects.

In order to address this issue, many approaches have been attempted to improve the therapeutic index of gemcitabine and other nucleoside prodrugs by developing lipid-nucleoside conjugates and nucleoside derivatives. See, e.g., Immodino et. al. J Controlled Release 100: 331-346 (2004), Kotchetkov et al Anticancer Res., 20, 2915-2922 (2000) and U.S. Patent Appl. Pub No. US2002/0082242 Al; See also Alexander et. al. J.MedChem., 46, 4205-4208 (2003), U.S Patent Nos. 5,051,499, 6,384,019 Bl and 4,921,951 and EP 0376518 Bl; See also Calvagno et ah, 2003 Controlled Release Society 30 ^th Annual Meeting Proceedings, Moog et. ah Cancer Chemother Pharmacol, 49, 356-366 (2002) and Alexander et. ah, J.MedChem., 46, 4205-4208 (2003). However, no development thus far, has successfully produced a pharmaceutical formulation comprising nucleoside-lipid conjugates of the formulas described herein. A need exists for such formulations and methods of producing them thereof.

Brief Summary of the Invention

The present invention provides novel formulations of nucleoside-lipid conjugates, the methods of preparing them and the methods for administering them. Specifically, methods for making liposomal formulations of nucleoside-cardiolipin and analogues thereof are provided.

Numerous advantages may be realized by the present invention, namely, protecting the drugs from degradation and, thereby, extending the drugs' plasma half-life and intracellular release as a result of the encapsulation of the prodrugs. Further, compositions that demonstrate greater efficacy and higher

cytotoxicity are produced. Accordingly, the nucleoside-lipid conjugates produced demonstrate greater in- vitro and in-vivo activity.

Other advantages and features of the invention will become apparent from the following description and from reference to the drawings.

Brief Description of the Drawings

FIG. 1 is a flow diagram depicting the thin-film hydration method used in preparing liposomes in accordance with the invention; and

FIG. 2 is a flow diagram depicting the solvent dilution method used in preparing liposomes in accordance with the invention.

Detailed Description of the Invention

The present invention provides novel liposomal formulations of nucleoside-lipid conjugates, specifically nucleoside-cardiolipin conjugates, the methods of preparing them and the methods for administering them.

The nucleoside-lipid conjugates comprise a novel class of nucleoside-cardiolipin analogues of formula I.

In formula I, Y ₁ and Y ₂ are the same or different and are -O-C(O)-, -O, -S-, -NH-C(O)- or the like and Ri and R ₂ are the same or different and are selected from a group consisting of H, saturated alkyl group and unsaturated alkyl group. Further, X is selected from a group consisting of H, alkyl group ranging from C ₁ to C ₁₀ and a cation, preferably a non-toxic cation such as ammonium, sodium, potassium,

calcium and barium. R ₃ is selected from a group consisting of cytosine, guanine, adenine, thymine, uracil, inosine, hypoxanthine and xanthine, wherein R ₃ is optionally substituted with one, two, three or four substituents selected from the group consisting of halo, nitro, alkyl, alkenyl, alkoxy, aryl, triflurormethyl, and N(R ^a )(R ^b ), wherein R ^a and R ^b are independently selected from the group consisting of H and (C ₁ -C ₈ ) alkyl. Still further, R ₄ and R ₅ are same or different and are selected from a group consisting of halo group (H, F, Cl, Br, I), nitro, hydroxyl, substituted alkyl, an alkyl group (C ₁ -C ₁₅ ) and an alkoxy group such as methoxy, ethoxy, propoxy, butoxy, and polyalkoxy. Lastly, R ₅ is selected from a group consisting of H, OH, azido group, amino group, substituted amino, alkyl group and halo group.

The nucleoside-lipid conjugates also comprise a novel class of nucleoside-cardiolipin analogues of formula II.

Il

In formula II, Y ₁ and Y ₂ are the same or different and are -O-C(O)-, -0-, -S-, -NH-C(O)- or the like and R ₁ and R ₂ are the same or different and are selected from a group consisting of hydrogen, saturated alkyl group and unsaturated alkyl group. Further, R ₃ and R ₇ are same or different and are selected from a group consisting of cytosine, guanine, adenine, thymine, uracil, inosine, hypoxanthine and xanthine, wherein R ₃ and/or R ₇ are optionally substituted with one, two, three or four substituents selected from the group consisting of halo, nitro, alkyl, alkenyl, alkoxy, aryl, triflurormethyl and N(R ^a )(R ^b ), wherein R ^a and R ^b are independently selected from the group consisting of H and (C ₁ -C ₈ ) alkyl. R _t and R ₅ are same or different and are selected from a group consisting of halo group (H, F, Cl, Br, I), nitro, hydroxyl, substituted alkyl, alkyl group (C ₁ -C ₁₅ ) and alkoxy group such as methoxy, ethoxy, propoxy, butoxy or polyalkoxy group. Lastly, R ₅ is selected from a group consisting of H, OH, azido group, amino group, substituted amino, alkyl group and halo group.

The nucleoside-lipid conjugates still further comprise a novel class of nucleoside-cardiolipin analogues of formula III.

In formula III, Y ₁ and Y ₂ are the same or different and are -O-C(O)-, -0-, -S-, -NH-C(O)- or the like and Ri and R ₂ are the same or different and are selected from a group consisting of H, saturated and unsaturated alkyl group. X is selected from a group consisting of H, alkyl group ranging from Ci to C ₁₀ and a cation, preferably a non-toxic cation such as ammonium, sodium, potassium, calcium and barium. Further, R ₃ is selected from a group consisting of cytosine, guanine, adenine, thymine, uracil, inosine, hypoxanthine and xanthine, wherein R ₃ is optionally substituted with one, two, three or four substituents selected from the group consisting of halo, nitro, alkyl, alkenyl, alkoxy, aryl, trifluoromethyl, and N(R ^a )(R ^b ), wherein R ^a and R ^b are independently selected from the group consisting of H and (C ₁ -C ₈ ) alkyl groups. R ₄ and R ₅ are same or different and are selected from a group consisting of halo group (H, F, Cl, Br, I), nitro, hydroxyl, substituted alkyl, alkyl group (C ₁ -C ₁₅ ) and alkoxy group such as methoxy, ethoxy, propoxy, butoxy and polyalkoxy.

The nucleoside-lipid conjugates also comprise a novel class of nucleoside-cardiolipin analogues of formula IV.

IV

In formula IV, Y ₁ and Y ₂ are the same or different and are -O-C(O)-, -0-, -S-, -NH-C(O)- or the like and R ₁ and R ₂ are the same or different and are selected from a group consisting of H, saturated alkyl group and unsaturated alkyl group. R ₃ and R ₇ are the same or different and are selected from a group

consisting of cytosine, guanine, adenine, thymine, uracil, inosine, hypoxanthine and xanthine, wherein R ₃ and/or R ₇ is optionally substituted with one, two, three or four substituents selected from the group consisting of halo, nitro, alkyl, alkenyl, alkoxy, aryl, trifluoromethyl and N(R ^a )(R ^b ), wherein R ^a and R ^b are independently selected from the group consisting of H and (C _r C ₈ ) alkyl. Still further, R ₄ and R ₅ are same or different and are selected from a group consisting of halo group (H, F, Cl, Br, I), nitro, hydroxy 1, substituted alkyl, alkyl group (C ₁ -Ci ₅ ) and alkoxy group such as methoxy, ethoxy, propoxy, butoxy and polyalkoxy.

The term "linker" is defined herein as a group or chain containing one or more functional groups for covalent binding with the lipid carrier and biologically active nucleoside. Preferred embodiments comprise a linker having at least two functional groups, wherein the linker has a first end and a second end and wherein the lipid is attached to the first end of the linker through a first linker functional group and the nucleoside is attached the second end of the linker through a second linker functional group. These groups can be designated either as weak or strong, based on the stability of the covalent bond which the linker functional group will form between the linker and either the lipid carrier or the biologically-active nucleoside. The weak functionalities include, but are not limited to, phosphoramidite, phosphoesters (such as phosphodiester, phosphotriester and phosphonate), carbonate, amide, carboxyl-phosphoryl anhydride, ester and thioester. The strong functionalities include, but are not limited to, ether, thioether, amine, amide, and ester. The use of a strong linker functional group between the linker and the nucleoside will tend to decrease the rate at which the compound will be released in vivo, whereas the use of a weak linker functional group between the linker and the nucleoside may act to facilitate in vivo release of the compound. In preferred embodiments, each of the first and second functional linker groups is a hydroxyl group, a primary or secondary amino group, a phosphate group or a substituted derivative thereof, a carboxylic acid, carbonate, carbamate or a carbonyl group. The "linker" herein also comprises, in addition to the functional groups at either end, (CH ₂ ) _n groups (where n = 0-20) in the center optionally substituted with functional groups, such as alkyl, alkoxy, hydroxyl, carbonyl, carboxyl, carbamate, aldehyde, amino, halo, polyalkoxy, PEG groups, phosphate, phosphonate and pyrophosphate groups.

The term "lipid" as used herein includes cardiolipin and cardiolipin derivatives or analogues having varying fatty acid and or alkyl chain with or without unsaturation.

The term "alkyl" encompasses saturated or unsaturated straight chain and branched-chain hydrocarbon moieties. The term "substituted alkyl" comprises alkyl groups further bearing one or more substituents selected from hydroxyl, alkoxy (of a lower alkyl group), mercapto (of a lower alkyl group), cycloalkyl, substituted cycloalkyl, halogen, cyano, nitro, amino, amido, imino, thio, -C(O)H, acyl, oxyacyl, carboxyl and the like. X is more preferably H, methyl, ethyl, benzyl, ammonium or sodium ion.

In a preferred embodiment, for formulae I-IV, the five-membered cyclic sugar is ribofuranose, arabinofuranose, deoxyribofiiranose or xylofuranose. The nomenclature is based on the specific orientation or absence of the hydroxyl groups at C2' and C3' position and the attachment of the heterocylic base at Cl'.

It must be noted that the nucleoside moiety, in the formulae above (I-IV), does not indicate the stereochemistry of the compounds of the present invention, and the stereochemistry is not a critical aspect of the invention. Accordingly, it will be understood that the present invention refers to a nucleoside-lipid conjugate of all possible stereochemical orientations, while recognizing that certain stereochemical species will be found to be more effective than other orientations. For example, it has been found that nucleosides with β configuration (attachment of base to the 5-membered cyclic sugar at C-I ') are more efficacious than the α-nucleosides. The β-nucleosides are, therefore, preferred compounds for making the present nucleoside-lipid conjugates.

In a preferred embodiment, for formulae I-IV, Ri and R ₂ are the same or different and are selected from a group comprising Ci-C ₂₄ saturated and/or unsaturated alkyl group, more preferably between Ce and Ci ₈ carbon atoms.

Further, in a preferred embodiment R ₃ is cytosine, guanine, adenine, thymine, uracil, inosine, hypoxanthine or xanthine. R ₃ is optionally substituted with one, two, three or four substituents selected from the group consisting of halo, nitro, alkyl, alkenyl, alkoxy, aryl, trifluoromethyl and N(R ^a )(R ^b ), wherein R ^a and R ^b are independently selected from the group consisting of H and (C ₁ -C ₈ ) alkyl.

Still further, in a preferred embodiment, R ₄ and R ₅ are the same or different and are selected from a group consisting of halo (F, Cl, Br, I), nitro, hydrogen, hydroxyl, alkyl, substituted alkyl and alkoxy, such as methoxy, ethoxy, propoxy or butoxy group.

In a preferred embodiment, R ₆ is preferably hydrogen, hydroxyl group, azido, amino, substituted amino or halo (F, Cl, Br, I) group.

Yet still further, in a preferred embodiment, the linker comprises an alkyl, substituted alkyl, dicarbonyl alkyl (for example, succinimidoyl group), alkoxy, polyalkoxy, PEGylated (PEG) group, phosphate, phosphonate, diphosphate, triphosphate, phosphodiester, phosphotriester, phosphoramidite, a peptide, dipeptide, polypeptide and the like.

In a more preferred embodiment, the compound, according to general formula I, is a gemcitabine- cardiolipin conjugate having the structures V and VI, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro, Rj is hydroxy 1 group, X is methyl or ammonium, Yi and Y ₂ are oxo (-O-) groups, the linker is succinimidoyl group and

©

VI, X = NH4

Ri and R ₂ are the same or different and are H, C ₁ -C ₃₄ saturated or unsaturated alkyl groups.

Further, in a more preferred embodiment, the compound, according to general formula I, is a gemcitabine-cardiolipin conjugate having the structures VII and VIII, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro, R ₅ is hydroxyl group, X is methyl or ammonium, Yi and Y ₂ are -O-C(O)-, the linker is a succinimidoyl group and

© VIII, X= NH4

Ri and R ₂ are the same or different and are H, CpC ₃₄ saturated or unsaturated alkyl groups.

Still further, in a more preferred embodiment, the compound, according to general Formula I, is a gemcitabine-cardiolipin conjugate having the structures IX and X, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro, R ₅ is hydroxyl group, X is methyl or ammonium, Yi and Y ₂ are oxo (-0-) groups, the linker is a succinimidoyl group and

X, X = NH4

R ₁ is H, C ₁ -C ₃₄ saturated or unsaturated alkyl groups and R ₂ is a methyl group.

In a more preferred embodiment, the compound, according to general formula III, is a gemcitabine-cardiolipin conjugate having the structures XI and XII, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro groups, X is methyl or ammonium, Yi and Y ₂ are oxo (-0-) groups, the linker is succinimidoyl group and

© XII ₁ X = NH4

R ₁ and R ₂ are the same or different and are H, C ₁ -C ₃₄ saturated or unsaturated alkyl groups.

Further, in a more preferred embodiment, the compound, according to general formula III, is a gemcitabine-cardiolipin conjugate having the structures XIII and XIV, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro group, X is methyl or ammonium, Y ₁ and Y ₂ are -0-(CO)- groups, the linker is a succinimidoyl group and

©

X1V, X = NH4

Ri and R ₂ are the same or different and are H, CpC ₃₄ saturated or unsaturated alkyl groups.

Still further, in a more preferred embodiment, the compound, according to general Formula III, is a gemcitabine-cardiolipin conjugate having the structures XV and XVI, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro group, X is methyl or ammonium, Yi and Y ₂ are oxo (-0-) groups, the linker is succinimidoyl group and

θ XVI, X = NH4

Ri is H, Ci-C ₃₄ saturated or unsaturated alkyl groups and R ₂ is a methyl group.

In a more preferred embodiment, the compound, according to general Formula I, is a gemcitabine- cardiolipin conjugate having the structures XVII and XVIII, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro, R ₆ is hydroxy I group, X and R ₈ are methyl or ammonium, Yi and Y ₂ are oxo (-0-) groups, the linker is a phosphodiester (R ₈ is ammonium) or phosphotriester (R ₈ is a methyl) and

© XVIII, X = NH4

Ri and R ₂ are the same or different and are H, C ₁ -C ₃₄ saturated or unsaturated alkyl groups.

Further, in a more preferred embodiment, the compound, according to general formula I, is a gemcitabine-cardiolipin conjugate having the structures XIX and XX, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro, R ₅ is hydroxyl group, X and R ₈ are methyl or ammonium, Y ₁ and Y ₂ are -0-(CO)- groups, the linker is a phosphodiester (R ₈ is ammonium) or phosphotriester (R ₈ is a methyl) and

© XX, X = NH4

Ri and R ₂ are the same or different and are H, C ₁ -C ₃₄ saturated or unsaturated alkyl groups.

Still further, in a more preferred embodiment, the compound, according to general formula I, is a gemcitabine-cardiolipin conjugate having the structures XXI and XXII, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro, R ₅ is hydroxyl group, X and R ₈ are methyl or ammonium, Y ₁ and Y ₂ are oxo (-O-) groups, the linker is a phosphodiester (R ₈ is ammonium) or phosphotriester (R ₈ is a methyl) and

θ XXII, X = NH4

Ri is H, CpC ₃₄ saturated or unsaturated alkyl groups, and R ₂ is methyl group.

In a more preferred embodiment, the compound, according to general formula III, is a gemcitabine-cardiolipin conjugate having the structures XXIII and XXIV, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro groups, X and Rs are methyl or ammonium, Yi and Y ₂ are oxo (-0-) groups, the linker is a phosphodiester (R ₈ is ammonium) or phosphotriester (R ₈ is a methyl) and

©

XXIV, X = NH4

Ri and R ₂ are the same or different and are H, CpC ₃₄ saturated or unsaturated alkyl groups.

Further, in a more preferred embodiment, the compound, according to general formula III, is a gemcitabine-cardiolipin conjugate having the structures XXV and XXVI, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro groups, X and R ₈ are methyl or ammonium, Yi and Y ₂ are -0-(CO)- groups, the linker is a phosphodiester (R ₈ is ammonium) or phosphotriester (R ₈ is a methyl) and

© XXVI, X = NH4

Ri and R ₂ are the same or different and are H, C ₁ -C ₃₄ saturated or unsaturated alkyl groups.

Still further, in a more preferred embodiment, the compound, according to general formula III, is a gemcitabine-cardiolipin conjugate having the structures XXVII and XXVIII, wherein R ₃ is cytosine, R ₄ and R ₅ are fluoro groups, X and R ₈ are methyl or ammonium, Y ₁ and Y ₂ are oxo (-0-) groups, the linker is a phosphodiester (R ₈ is ammonium) or phosphotriester (R ₈ is a methyl) and

©

XXVIII, X = NH4

R ₁ is H, C ₁ -C ₃₄ is saturated or unsaturated alkyl groups, and R ₂ is a methyl group.

In a more preferred embodiment, the compound, according to general formula II, is a gemcitabine-cardiolipin conjugate having the structure XXIX, wherein R ₃ and R ₇ are cytosine, R ₄ and R ₅ are fluoro, R ₆ is hydroxyl, Y ₁ and Y ₂ are oxo (-0-) or -0-C(O)- groups, the linker is - CH ₂ CH ₂ CH ₂ NHCOCH ₂ CH ₂ C(O)-group and

XXIX

Ri and R ₂ are the same or different and are H, CpC ₃₄ saturated or unsaturated alkyl groups

In a more preferred embodiment, the compound, according to general formula IV, is a gemcitabine-cardiolipin conjugate having the structure XXX, wherein R ₃ and R ₇ are cytosine, R ₄ and R ₅ are fluoro, Y ₁ and Y ₂ are oxo (-0-) or -OC(O)- groups, the linker is -CH ₂ CH ₂ CH ₂ NHCOCH ₂ CH ₂ C(O)-group and

xxx

Ri and R ₂ are the same or different and are H, CpC ₃₄ saturated or unsaturated alkyl groups

In addition to the nucleoside-lipid conjugate, the formulation may further comprise phospholipids and/or lysophospholipids. Suitable phospholipids include phosphatidylcholine (PC),

phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylglycerol (PG), phosphatidic acid (PA), phosphatidylinositol (PI), sphingomyelin (SPM), lysophosphotidylglycerol, lysophosphatidic acid, lysophosphotidylcholine, lysophosphatidylserine, polymer modified lipids, such as PEG modified lipids and the like, alone or in combination. Phosphatidylglycerols such as dimyristoylphosphatidylglycerol, dioleoylphosphatidylglycerol, distearoylphosphatidylglycerol, dipalmitoylphosphatidylglycerol, diarachidonoylphosphatidylglycerol and mixtures thereof may also be used. In addition, the phospholipids, dimyristoylphosphatidylcholine (DMPC), distearoylphosphatidylcholine (DSPC), dipalmitoylphosphatidylcholine (DPPC), diarachidonoyl phosphatidylcholine (DAPC), egg phosphatidylcholine, soy phosphatidylcholine or hydrogenated soy phosphatidylcholine (HSPC) can be used as well as mixtures thereof. Other lipids that may be employed include ganglioside (GMl) and polymer modified lipids thereof, synthetic or natural cardiolipin and analogues thereof and synthetic positively charged cardiolipin and analogues thereof.

Any suitable amount of nucleoside-lipid conjugate may be employed. Suitable amounts of nucleoside-cardiolipin analogue concentrations include from about 0.1 mg/mL or more to about 50 mg/mL, such as between about 0.1 mg/mL to about 35 mg/mL, between about 0.5 mg/mL to about 25 mg/mL, between about 1 mg/mL to about 20 mg/mL, between about 5 mg/mL to about 20 mg/mL or between about 10 mg/mL to about 20 mg/mL. Suitable compositions also generally contain a molar ratio of nucleoside-cardiolipin analogue to lipids of about 1:1 to about 1:7, such as between about 1 :2 to about 1:5 or about 1 :3. In addition, suitable liposomes or lipid complexes comprise at least about 10 wt.% or more of the nucleoside- cardiolipin analogue, more preferably at least 70 wt. % or more, even more preferably about 90 wt.% or more and most preferably about 95 wt.% or more, such as about 99 wt.% or more.

The nucleoside-lipid conjugate formulations may also include at least one sterol or steroid component such as cholesterol, polyethylene glycol derivatives of cholesterol (PEG-cholesterols), coprostanol, cholestanol or cholestane or α-tocopherol. They may also contain sterol derivatives such as cholesterol hemisuccinate (CHS), cholesterol sulfate and the like. Organic acid derivatives of tocopherols, such as α-tocopherol hemisuccinate (THS), can also be used.

Liposomes, according to the present invention, can be multilamellar vesicles, unilamellar vesicles, or a mixture thereof. Moreover, the liposomes can be of varying size or can be substantially uniform in size. For example, the liposomes can have a size range of about 1 mm or less and, more preferably, are in the micron or sub-micron range. For example, the liposomes can have a diameter of about 5μm or less, such as about lμm or less, or even about 0.5μm or less, such as about 0.2μm or less or even about O.lμm or less. In addition, suitable liposomes may be neutral, negatively or positively charged.

In addition to the nucleoside-lipid conjugates, liposomes can include stabilizers, absorption enhancers, antioxidants, phospholipids, biodegradable polymers and medicinally active agents, among other ingredients.

In some embodiments, it is preferable for liposomes also to include targeting agents such as a carbohydrate, or a protein or ligands that bind to a specific substrate, such as antibodies (or fragments thereof) or ligands that recognize cellular receptors. The inclusion of such agents (such as a carbohydrate, or one or more proteins selected from groups of proteins consisting of antibodies, antibody fragments, peptide, peptide hormones, receptor ligands, such as an antibody to a cellular receptor, and mixtures thereof) can facilitate targeting the liposome to a predetermined tissue or cell type. For example, U.S.

Patent No. 6,056,973, which is herein incorporated by reference, discloses a number of targeting agents and target cells. See Col. 11, 1. 1-41.

Liposomes, according to the present invention, can be prepared by any suitable technique. These methods include thin film hydration, as illustrated in FIG. 1 and reverse-phase evaporation, solvent dilution procedures, as illustrated in FIG. 2. Further methods include infusion procedures (not illustrated) and detergent dilution (not illustrated). A review of these and other methods for producing liposomes can be found in the text Liposomes., Marc J. Ostro, ed., Marcel Dekker, Inc., New York, Chapter 1 (1983), which is herein incorporated by reference.

For the thin-film hydration method as illustrated in FIG. 1, the dissolved lipophilic ingredients are mixed together (including the nucleoside-cardiolipin conjugate) and then the solvent(s) are evaporated or lyophilized to form a (preferably homogenous) lipid phase or lipid film. The lipid phase can be formed, for example, in a suitable organic solvent, such as is commonly employed in the art. Suitable solvents include any non-polar or slightly polar solvent, such as ?-butanol, ethanol, methanol, chloroform, methylene chloride, ethyl formate, methyl acetate or acetone that can be evaporated without leaving a pharmaceutically unacceptable residue. Drying can be by any suitable means such as by lyophilization or vacuum drying.

The dried lipid phase is then hydrated with a polar aqueous solution so as to form a lipid composition including the compound. Mixing the polar solution with the dry lipid phase can be by any means that strongly homogenizes the mixture. The homogenization can be effected by vortexing, magnetic stirring and/or sonicating.

Once formed, the liposomes can be treated, after the aqueous phase, to produce a homogenous population of liposomes. These methods include extrusion, ultrasonic exposure, the French press

technique, hydrodynamic shearing, and homogenization using, for example, a homogenizer or microfluidization techniques. The preferred method involves the extrusion of liposomes after the aqueous phase. For the extrusion technique, suitable filters include those that can be used to obtain the desired size range of liposomes from a filtrate. For example, the liposomes can be formed and thereafter filtered through a 5 micron filter to obtain liposomes of about 5 microns or less. Alternatively, 1 μm or less, 500 nm or less, 200 nm or less, 100 nm or less or other suitable filters can be used to obtain liposomes of desired size. The preferred method uses a lOOnm filter.

Once the liposomes are treated to produce a homogenous population of liposomes, the liposomes may be sterilized. To obtain a sterile pharmaceutical product, the liposomes may be filtered through microbial retentative filters (.22μm filters or less). Other methods of sterilization include steam autoclaving and gamma irradiation.

To improve the shelf life, the liposomes can be dried or dehydrated to form a dried liposome or lipid complex using standard freeze-drying equipment or equivalent apparatus, wherein the dehydration or drying is conducted under reduced pressure. In addition, the liposomes or lipid complexes may be frozen in liquid nitrogen before dehydration.

Another preferred step, to improve the shelf life of the compositions, includes the additions of sugars. These sugars are selected from a group consisting of trehalose, maltose, lactose, sucrose, glucose and dextran. The more preferred sugars from this group are trehalose and sucrose. In addition, other more complicated sugars may be used such as aminoglycosides, including streptomycin and dihydrostreptomycin. The sugars are added at any point after the lipid phase. The preferred method involves the addition of the sugars during the addition of the aqueous solution, wherein the sugars are dissolved in the aqueous solution prior to adding the aqueous phase to the lipid solution.

The liposomal composition may be reconstituted with suitable diluents. These diluents are selected from a group consisting of 5% dextrose, sodium chloride (0.9% NaCl), sterile water, lactated Ringer's solution and mixtures thereof.

The present invention also includes the use of the liposomal formulation, as disclosed herein, in human and veterinary medicine for the prevention, alleviation and/or cure of diseases, in particular those diseases caused by cellular proliferation, such as cancer, in any mammal. However, it is particularly preferred for the treatment of human patients, particularly for cancer and other diseases caused by cellular proliferation. Examples of cancer treatable by the present invention include, but are not limited to, cancers of the head, neck, brain, blood (e.g. leukemia, acute leukemia, acute lymphocytic leukemia, acute

myelocytic leukemia, lymphoma, myeloma), breast, lung, pancreas, spleen, bladder, prostate, testes, colon, kidney, ovary and skin. In addition, the new nucleoside-cardiolipin liposomes of this invention are potentially useful in the treatment or alleviation of bone disorders. These conjugates can be used in methods for inhibiting bone resorption, methods for increasing bone formation by preventing osteoblast and osteocyte apoptosis and methods for increasing bone mass and strength. Indications for their use include the treatment or alleviation of osteoporosis, Paget's disease, metastatic bone cancers, hyperparathyroidism, rheumatoid arthritis, algodistrophy, sterno-costo-clavicular hyperostosis, Gaucher's disease, Engleman's disease and certain non-skeletal disorders.

In addition to cancer, the present invention is potentially useful in the treatment of viral diseases such as HIV, herpes simplex virus (HSVl and HSV2), human herpes virus 6, human herpes virus 7, human herpes virus 8, orthopoxviruses (e.g. variola major and minor and small pox), ebola virus, influenza virus, tuberculosis, hepatitis A, hepatitis B, hepatitis C, hepatitis D, hepatitis E, hepatitis G, parainfluenza virus, respiratory syncytial virus, cholera, pneumonia, SARS virus, canary virus, West Nile virus (WNV), dengue virus, vericella zoster virus, corona virus, vaccinia virus, cytomegalovirus (CMV), human rhinovirus (HRV), papilloma virus (PV) and Epstein Barr virus.

Furthermore, the compositions of this invention are useful in reducing the tendency of cancer cells subjected to chemotherapy or radiation to develop a resistance to other therapeutic agents. Thus, other therapeutic agents can be advantageously employed with the present invention in the formation of an active combination or by separate administration. The therapeutic agents include anti-cancer agents, chemotherapy and radiation. The term "therapeutic agent" herein means any compound or composition which, upon entering a mammalian cell, is capable of contributing to the alleviation or treatment of a mammalian disease. The mammalian cell can be any type of mammalian cell, including both cancerous and non-cancerous cells. The cancer can be any type of cancer in a mammal. By way of example and not by limitation, "therapeutic agents" include small organic molecules, peptides, nucleoside analogues, anticancer agents, antiviral agents, ribozymes, protease inhibitors, polymerase inhibitors, reverse transcriptase inhibitors, antisense oligonucleotides and other drugs. As used herein, the term "anticancer agent" means a therapeutic agent capable of exhibiting efficacy at combating a cancer in a mammal or in a mammalian cell, or any compound which is capable of being converted intracellularly to a compound which is capable of exhibiting efficacy at combating a cancer in a mammal or in a mammalian cell.

The additional therapeutic agent can become complexed with a portion of the lipid (such as the inventive nucleoside-lipid conjugate) or the therapeutic agent can become entrapped within the liposomes. Alternatively, the therapeutic agent can be administered separately. In addition, a second therapeutic agent can be administered adjunctively, prior to, concurrently with or after the first therapeutic agent. Preferred

agents include antineoplastic, antifungal, antibiotic and other therapeutic agents, particularly cisplatin, antisense oligonucleotides, siRNA, oxaliplatin, paclitaxel, vinorelbine and epirubicin.

It should be noted that, where the inventive nucleoside-conjugate liposomes are employed to treat or alleviate diseases (e.g., cancer, viral) in human or animal patients, they need not result in a complete cure or remission of the disease to be shown to be successfully employed. As used herein, "alleviating a disease" means reducing the severity of a symptom of the disease. Further, as used herein, "treating a disease" means reducing the frequency with which a symptom of the disease is experienced by a mammal. Thus, for example, the compositions can be successfully employed if, by using the inventive nucleoside- lipid conjugate, the progress of the disease is slowed or retarded in the patient. Alternatively, the inventive composition is deemed to have been used successfully in the treatment of the disease if, for adjunctive uses, the inventive nucleoside-lipid conjugate renders the disease more amenable to other treatment or demonstrates additive, but not necessarily synergistic, therapeutic potential as compared to monotherapy using other treatment regimen. However, in some embodiments, the use of the nucleoside-lipid conjugates in accordance with the present invention can lead to remission of cancer or other diseases.

The invention also includes pharmaceutical preparations of the liposomal composition in the form of tablets, dragees, capsules, pills, granules, suppositories, solutions suspensions and emulsions, pastes, ointments, gels, creams, lotions, powders and sprays. Suppositories can contain, in addition to the nucleoside-cardiolipin composition, suitable water soluble or water-insoluble excipients. Suitable excipients are those in which the inventive composition is sufficiently stable to allow for therapeutic use, for example polyethylene glycols, certain fats, and esters or mixture of substances. Ointments, pastes, creams and gels can also contain suitable excipients in which the inventive composition is stable.

For administration, the compositions of the present invention can be administered intravenously, subcutaneously, locally, orally, parenterally, intraperitoneally, and/or rectally, nasally, vaginally, lingually or by direct injection into tumors or other sites in need of treatment by such known and developed methods. The present pharmaceutical preparations can contain the nucleoside-lipid liposomes alone, or can contain further substances of pharmaceutical importance. They can further comprise a pharmaceutically acceptable carrier.

The invention also includes a kit for administering the compositions of the present invention to a mammal for the treatment or alleviation of a disease. The disease can be any one or more of the diseases described herein. The kit comprises the composition of the invention and an instructional manual which describes the administration of the composition to a mammal by any of the routes of administration described herein. In another embodiment, this kit comprises a solvent, preferably sterile, suitable for

dissolving or suspending the composition of the invention prior to administering the composition to the mammal.

Having described the present invention, references will not be made to an example which is provided solely for purposes of illustration and which is not ^' intended to be limiting.

EXAMPLE 1

The lipids and tocopheryl acid succinate were weighed and then placed into a tarred a 100 mL round bottom flask. Then, NEO6002, a gemcitabine-cardiolipin conjugate that is a conjugate with Cβ cardiolipin, was added into the same 100 mL round bottom flask. The lipids, tocopheryl acid succinate and NEO6002 were mixed and put into a warm water bath (40°C) to dissolve the components to clarity.

The round bottom flask was then connected to a rotary evaporator attached to a -10°C condenser and vacuum. Next, the lipid solution was heated to 40 ⁰ C with a water bath and rotated at 160 rpm. The solvent was then removed to form a lipid film on the wall of the flask. The flask remained connected to the vacuum for 1 hour after all the solvent was removed. 12.0 mL of 20% sucrose and 0.25% NaCl was added to the dry lipid film. Mixing was continued at 40 ⁰ C until the lipid film was completely suspended.

Next, the liposomes were size reduced using a 10 mL extruder at room temperature. The product was subsequently extruded three times through two stacked polycarbonate filters of 0.8 μm pore size, five times through two stacked polycarbonate filters of 0.2 μm pore size and ten times through two stacked polycarbonate filters of 0.1 μm pore size.

After extrusion, a sample was taken for size analysis and HPLC determination of active concentration. The results of this analysis are shown in Table 1.

Table 1

DOPC: l,2-Dioleoyl-sn-Glycero-3-PhosphochoUne DMPC: l^-Dimyristoyl-sw-Glycero-S-Phosphocholine DPPC: l^-Dipalmitoyl-s/i-Glycero-S-Phosphocholine CL: I,r,2,2'-Tetramyristoyl Cardiolipin NEO6002: Gemcitabine-cardiolipin analogues

PCL-2: Positive charged cationic cardiolipin analogue

*Physically stable means no phase separation, no drug crystal particles or precipitation observed under microscope, and liposome size remains constant.

All references, including publications, patent applications, and patents cited herein, including those in the preceding list and otherwise cited in this specification, are hereby incorporated by reference to the same extent as if each reference was individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. The use the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having", "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specifications should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments can become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the inventions to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.