RADIOLABELED COMPOUNDS THAT TARGET ORGANIC CATION TRANSPORTERS

AND USES THEREOF IN RADIOIMAGING

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to radiopharmaceuticals and, more particularly, but not exclusively, to novel radiolabeled compounds that target organic cation transporters and to use thereof in radioimaging (e.g., PET or SPECT), for example, for non-invasive detection of tumors that express organic cation transporters or in myocardial perfusion imaging.

Approximately half of all patients undergoing chemotherapeutic treatment

(chemotherapy) receive platinum-based drugs, the most common being cisplatin, carboplatin and oxaliplatin. Treatment with platinum-based drugs can be associated with inherent and/or acquired resistance. All platinum compounds share four main steps in their mechanism of action; (i) cellular uptake, (ii) aquation/activation (iii) DNA platination, and (iv) cellular processing of platinum-DNA lesions, leading to cell survival or apoptosis [Johnstone et al. Anticancer Res. Jan 2014; 34(l):471-476].

Although the cytotoxic effects of platinum compounds arise from the formation and processing of platinum-DNA lesions, the mechanisms responsible for the distinct tumor specificities and/or resistance may involve events other than their interactions with and binding to DNA. Thus, it has been recognized that reduced cellular accumulation is the most commonly observed defect is tumor cells that are resistant to platinum-based drugs [Zhang et al. Cancer Res. Sep 01 2006; 66(17):8847-8857]. Knowledge about the cellular accumulation (influx and efflux) of platinum compounds is imperative and could be used to predict treatment strategy, response and/or outcome.

While cellular uptake of platinum-based drugs was traditionally attributed to passive diffusion, in recent years, it has been recognized that transporters such as copper transporters (e.g., CTR1), and organic cation transporters such as solute carrier transporters of the SLC22 family (OCTl, OCT2 and OCT3), encoded by SLC22A1, 2 and 3, respectively, have been implicated as a major route for platinum access into the cell [Zhang et al. Cancer Res. Sep 01 2006; 66(17):8847-8857; Yokoo et al. Drug Metab Dispos. Nov 2008; 36(l l):2299-2306].

Various studies have shown that upregulation or overexpression of OCTs in vitro are associated with increased platinum accumulation and cytotoxicity [e.g., Zhang et al. Cancer Res. Sep 01 2006; 66(17):8847-8857; Yokoo et al. Drug Metab Dispos. Nov 2008; 36(11):2299- 2306]. For example, it has been found in these studies that overexpression of OCTl and OCT2 increased oxaliplatin accumulation and cytotoxicity in transfected cell lines. In addition, 11/20 colon cancer samples were found to express high levels of OCT2, whereas 4 normal colon tissue samples did not. On the same note, it was found in these studies that the OCT3 was highly expressed in some but not all colorectal cancer cell lines and tumor tissues. Cell lines with high OCT3 expression levels were also found to have increased oxaliplatin accumulation and cytotoxicity.

Another study has shown that a reduction in OCT3 expression levels in vitro was found to underlie cisplatin resistance [Li et al. J Pharm Sci. Jan 2012; 101(l):394-404].

It was further shown that high OCT2 level is correlated with longer PFS in FOLFOX (folinic acid, 5-FU and oxaliplatin combination therapy)-treated colorectal cancer patients (Tatsumi S, Int. J. Clin. Exp. Pathol. 2014, 7(1):204-12).

Hepatocellular carcinoma patients with higher OCT1 expression levels were also found to have better survival rates, even though no systemic treatment was given [Heise et al. BMC Cancer. Mar 22 2012; 12: 109], suggesting that prior knowledge about OCT expression in tumors could also have a prognostic value.

U.S. Patent Application Publication No. 2011/0293519 discloses radiolabeled ammonium salts and uses thereof in myocardial perfusion imaging.

Shamni O. in International Symposium on Radiopharmaceutical Sciences, May 2017, Dresden Germany, disclosed a fluorine- 18 labeled quinolinium salt as usable for myocardial perfusion imaging.

Additional background art includes Mishani E, International Conference on Innovation in Cancer Research and Care, Dec 2017, Bangkok, Thailand; and Grievink H, Annual Meeting of the Israeli Society of Nuclear Medicine, March 2018, Israel.

SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the present invention there is provided a radiolabeled compound represented by Formula I*:

Formula Γ wherein:

A ^" is an anion;

X is selected from hydrogen, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted aryl, a substituted or unsubstituted heteroalicyclic and R*;

m is 0 or an integer of from 1 to 3;

n is 0 or an integer of from 1 to 4;

Ri and R ₂ are each independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroalicyclic, heteroaryl, alkoxy, aryloxy, thioalkoxy, thioaryloxy, hydroxyl, halogen, trihaloalkyl, trihaloalkoxy, amine, cyano, nitro, carbonyl, thiocarbonyl, carboxylate, thioacarboxylate, amide, thioamide, carbamate, thiocarbamate, acrylate, methacrylate, acrylamide, alkaryl, aralkyl, sulfinyl, sylfonyl, sulfonate, sulfonamide, and a substituted or unsubstituted, a saturated or unsaturated hydrocarbon chain of 1 to 20 carbon atoms, optionally interrupted by one or more heteroatoms, and R*; and

R* is a radioactive atom or a group that comprises a radioactive atom,

provided that at least one of Ri, R ₂ and X is the R*.

According to some of any of the embodiments described herein, X is the R*.

According to some of any of the embodiments described herein, X is an alkyl, cycloalkyl, aryl or the hydrocarbon chain, which comprises one or more substituents, at least one of the substituents being the R*.

According to some of any of the embodiments described herein, the radiolabeled compound is represented by Formula Pa:

Formula Pa wherein:

L is the alkyl, cycloalkyl, aryl or the hydrocarbon chain or is absent; w is 0 or a positive integer;

q is a positive integer; and

R ₃ is selected from alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroalicyclic, heteroaryl, alkoxy, aryloxy, thioalkoxy, thioaryloxy, hydroxyl, halogen, trihaloalkyl, trihaloalkoxy, amine, cyano, nitro, carbonyl, thiocarbonyl, carboxylate, thioacarboxylate, amide, thioamide, carbamate, thiocarbamate, acrylate, methacrylate, acrylamide, alkaryl, aralkyl, sulfinyl, sylfonyl, sulfonate, sulfonamide, and a substituted or unsubstituted, a saturated or unsaturated hydrocarbon chain of 1 to 20 carbon atoms, optionally interrupted by one or more heteroatoms.

According to some of any of the embodiments described herein, L is alkyl and R* is the radioactive atom.

According to some of any of the embodiments described herein, L is absent and R* is the group that comprises the radioactive atom.

According to some of any of the embodiments described herein, w is 0.

According to some of any of the embodiments described herein, q is 1.

According to some of any of the embodiments described herein, the radioactive atom is a radioactive carbon or a radioactive halogen.

According to some of any of the embodiments described herein, the radioactive atom is a radioactive halogen.

According to some of any of the embodiments described herein, the radioactive halogen is fluorine- 18.

According to some of any of the embodiments described herein, n and m are each 0.

According to some of any of the embodiments described herein, the radiolabeled compound is:

wherein F* is a radioactive fluorine.

According to an aspect of some embodiments of the present invention there is provided a pharmaceutical composition comprising as an active ingredient the radiolabeled compound as described herein in any of the respective embodiments and any combination thereof and a pharmaceutically acceptable carrier.

According to an aspect of some embodiments of the present invention there is provided a radiolabeled compound as described herein in any of the respective embodiments and any combination thereof, or a pharmaceutical composition comprising said, as described herein, for use in radioimaging.

According to some of any of the embodiments described herein, the radioimaging comprises administering to a patient the radiolabeled compound or the composition and employing a nuclear imaging technique to thereby determine a presence and/or level and/or distribution of the compound in the patient's body or a portion thereof.

According to some of any of the embodiments described herein, the radioimaging is for determining and/or monitoring a presence and/or level and/or distribution of an organic cation transporter within the body of the patient.

According to some of any of the embodiments described herein, the radioimaging is for determining if the patient has a disease or disorder that is treatable by or responsive to a therapy whose efficacy correlates with a presence and/or level and/or distribution of an organic cation transporter (e.g., a therapy that exploits an expression and/or activity of an OCT).

According to some of any of the embodiments described herein, the patient is diagnosed as having, or as suspected of having, the disease or disorder and the radioimaging is for determining if the disease or disorder is treatable by the therapy.

According to some of any of the embodiments described herein, the radioimaging is performed following the therapy, and is for determining a responsiveness or an emergence of a resistance to the therapy.

According to some of any of the embodiments described herein, the disease or disorder is a proliferative disease or disorder.

According to some of any of the embodiments described herein, the radioimaging is for determining and/or monitoring a presence and/or level and/or distribution of an organic cation transporter in a tumor tissue within the body of the patient.

According to some of any of the embodiments described herein, the therapy comprises a platinum-based chemotherapy.

According to some of any of the embodiments described herein, the proliferative disease or disorder is metastatic colorectal cancer.

According to an aspect of some embodiments of the present invention there is provided a radiolabeled compound as described herein in any of the respective embodiments and any combination thereof, or a composition comprising same, as described herein, for use in the treatment of a patient diagnosed with a disease or disorder that is treatable by a therapy whose efficacy correlates to a level and/or presence of an organic cation transporter, the treatment comprising:

administering the radiolabeled compound or the composition to the patient;

determining a presence and/or level and/or distribution of the radiolabeled compound in the patient's body or a portion thereof by employing a nuclear imaging technique, the presence and/or level being indicative of the patient's responsiveness to the therapy; and

based on the determining, subjecting the patient to the therapy or to a different therapy. According to some of any of the embodiments described herein, following the determining the patient is subjected to the therapy for a first time period, the method further comprising, following the first time period, determining a responsiveness or an emergence of a resistance to the therapy, the determining comprising:

administering the radiolabeled compound or the composition to the patient;

determining a presence and/or level and/or distribution of the radiolabeled compound in the patient's body or the portion thereof by employing the nuclear imaging technique, the presence and/or level being indicative of the patient's responsiveness to the therapy; and

based on the determining, subjecting the patient to the therapy for a second time period or subjecting the patient to a different therapy for the second time period.

According to some of any of the embodiments described herein, the radioimaging is for determining a presence and/or level of an impaired structure or function of an OCT-expressing cell, tissue and/or organ in the patient.

According to some of any of the embodiments described herein, the radioimaging is for determining a presence and/or level of a disease or disorder associated with an impaired structure or function of an OCT-expressing cell, tissue and/or organ in the patient.

According to some of any of the embodiments described herein, the patient is suspected as having, or has a predisposition to having, the disease or disorder.

According to some of any of the embodiments described herein, the OCT-expressing cell, tissue and/or organ is a myocardial tissue, the heart muscle or a portion of the heart muscle.

According to some of any of the embodiments described herein, the radioimaging is for determining a presence and/or level of a cardiovascular disease or disorder or a cardiac disease or disorder.

According to some of any of the embodiments described herein, the radioimaging is myocardial perfusion imaging. According to some of any of the embodiments described herein, the radioimaging is for determining efficacy of a therapy of the disease or disorder, and/or is utilized in a treatment of the disease or disorder, as described herein.

According to some of any of the embodiments described herein, the technique is positron emission tomography.

According to some of any of the embodiments described herein, the technique is single photon emission computed tomography.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

In the drawings:

FIGs. 1A-C present plots showing time-course of [ 18 F]FEtQ uptake into HEK293 cells expressing OCT1 (FIG. 1A), OCT-2 (FIG. IB) and OCT-3 (FIG. 1C), compared to cells transfected with an Empty Vector (EV). Each experiment was repeated twice using triplicate samples. Results are presented as mean + SEM.

FIG. 2 is a bar graph demonstrating the inhibition of [ 18 F]FETQ cellular uptake by corticosterone in HEK293 cells stably transfected with Empty Vector or hOCT3. Each experiment was repeated twice using triplicate samples. Data is presented as the mean ± SEM.

FIGs. 3A-B present comparative time-activity curves obtained following i.v. injection of

[ 18 F]FEtQ into male SD rats (n = 7), in the left ventricle (red circles), blood (blue rectangular), lungs (purple triangles) and liver (green triangles) (FIG. 3A) and in the kidneys (orange diamonds; FIG. 3B). Results are presented as mean + SEM. FIGs. 4A-D present representative PET/CT coronal (FIG. 4A), axial (FIG. 4B), sagittal (FIG. 4C) and maximum-intensity projection (FIG. 4D) images obtained at 25-45 minutes following injection of [ 18 F]FEtQ into a male SD rat.

FIGs. 5A-C present comparative time-activity curves of the LV (FIG. 5A), liver (FIG. 5B) and kidneys (FIG. 5C) obtained following i.v. injection of [ 18 F]FEtQ into corticosterone-treated or vehicle-treated male SD rats (n = 3). Results are presented as mean + SEM.

FIGs. 6A-D present PET-CT images of a non-human primate (NHP). Maximum intensity projection PET/CT images of a NHP following i.v. injection of [ 18 F]FEtQ. Images represent the summation of 0-15 minutes (FIG. 6A), 19-28 minutes (FIG. 6B), 30-39 minutes (FIG. 6C) and 41-50 minutes frames (FIG. 6D) after injection.

FIGs. 7A-E present data showing in vivo uptake and blocking of [ 18 F]FEtQ. Representative axial (FIG. 7 A and 7B) and coronal (FIGs. 7C and 7D) PET/CT slice images 20-

60 minutes after i.v. injection with [ 18 F]FEtQ into mice bearing tumors of hOCT2 expressing HEK293 cells (HEK-OCT2), without (FIGs. 7A and 7C) and with (FIGs. 7B and 7D) pre- injection of D-22 (0.38 mg/ kg). Green arrowheads point at the tumors. FIG. 7E presents time activity curves of [ 18 F[FEtQ uptake in the HEK-OCT2 tumors in the vehicle (n=3) and D-22 (n=2) treated animals. Data are presented as mean + SEM.

FIG. 8 presents time activity curves of [ 18 F[FEtQ uptake following i.v. injection into mice bearing tumors of hOCT2 expressing HEK293 cells (HEK-OCT2) in the vehicle (n=7) and D-22 (n=5) treated animals. Data are presented as mean + SEM.

FIGs. 9A-B present time-activity curves obtained following i.v. injection of [ ^u C]MeQ into male SD rats, in the left ventricle and liver (green triangles) (FIG. 9A), and representative PET/CT coronal, axial and sagittal images obtained at 10-25 minutes following injection of [ ⁿ C]MeQ into a male SD rat (FIG. 9B). DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to radiopharmaceuticals and, more particularly, but not exclusively, to novel radiolabeled compounds that target organic cation transporters and to use thereof in radioimaging (e.g., PET or SPECT), for example, for non-invasive detection of cancers that express organic cation transporters or in myocardial perfusion imaging.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details set forth in the following description or exemplified by the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways. The present inventors have realized that since organic cation transporters (OCT) play an important role in the uptake, elimination and distribution of drugs, determining a presence, level and/or distribution of OCTs in a patient's body can be a useful tool for selecting a suitable therapy for treating a medical condition in the patient, and for monitoring the therapy's efficacy.

The present inventors have thus conceived that radioactive agents that target OCTs in a patient would allow determining a presence, level and/or distribution of OCTs in the patient's body by a radioimaging technique, and would thereby provide highly useful information for determining and monitoring a suitable therapy for a medical condition in the patient, particularly in cases where the therapy correlates with intracellular accumulation of a drug.

The present inventors were prompt by the recognition that high OCT expressing tumors are more sensitive to treatment with platinum-based drugs, as in these tumors the OCTs play a more prominent role in the influx, accumulation, and eventual cytotoxicity of these agents. The present inventors have conceived that non-invasive systemic screening of OCT-overexpressing tumors could provide information useful for devising treatment strategy, outcome prediction, and could also be employed for detecting resistance development through loss of OCT expression.

The present inventors have thus conceived that an OCT-targeting radiolabeled compound could be employed for imaging OCT-expressing tumors by a radioimaging technique such as PET or SPECT.

The present inventors have further recognized that an OCT-targeting radiolabeled compound could be employed for imaging other OCT-expressing tissues and/or organs, by a radioimaging technique such as PET or SPECT, and that such imaging can be useful for evaluation an impaired structure and/or function of such organs and/or tissues. For example, the present inventors have realized that OCTs are expressed in cardiac tissues and have thus conceived that OCT-targeting radiolabeled compounds can be a useful tool in myocardial perfusion imaging,

While reducing the present invention to practice, the present inventors have devised and successfully prepared radiolabeled compounds that share structural features of a known agent that targets (inhibits) human OCT 1-3, decynium-22 (D-22) [Hayer-Zillgen et al. Br J Pharmacol. Jul 2002;136(6):829-836; Koepsell et al. Pharm Res. Jul 2007;24(7): 1227-1251]:

The present inventors have shown that utilizing radiolabeled compounds having a quinolinium skeleton in radioimaging enables non-invasive systemic detection of OCT- expressing tumors.

More specifically, as demonstrated in the Examples section that follows, the present inventors have prepared an exemplary fluorine- 18 labeled quinolinium salt compound, referred to herein as [ 18 F]fluoroethylquinolinium ([ 18 F]FEtQ), by a one-step radiosynthesis, and have first shown that the uptake of this compound by OCT-transfected cells is substantially higher than in empty vector cells (see, FIG. 1), and is adversely affected in the presence of an OCT inhibitor (see, FIG. 2).

The present inventors have conducted in vivo studies for evaluating the uptake and the clearance of this radiolabeled compound and the obtained data is presented in FIGs. 3A-C, 4A-D and 6A-D. In vivo studies in the presence of an OCT inhibitor corroborated the effect of such inhibitors on the cellular uptake of the [ 18 F]FEtQ, as shown in FIGs. 5A-C and 7A-E.

The present inventors have further shown that utilizing radiolabeled compounds having a quinolinium skeleton enables imaging of OCT-expressing tissues such as a cardiac tissue.

The present inventors have shown a pronounced LV uptake of [ 18 F]FEtQ (see, FIG. 3A) and successful imaging of the LV and good contrast between the heart and its surrounding tissues in rats (see, FIGs. 4A-D).The present inventors have also successfully prepared and practiced a carbon- 11 labeled quinolinium salt compound and have shown high LV uptake of this agent as well. See, FIGs. 9A-B.

Embodiments of the present invention therefore relate to novel radiolabeled compounds that target an OCT in a patient's body. Embodiments of the present invention further relate to using such radiolabeled compounds in radioimaging, for determining a presence and/or level and/or distribution of OCTs in the patient's body, for determining a suitable therapy for the patient based on the presence and/or level and/or distribution of OCTs in the patient's body, and/or for monitoring the progress of a medical condition in the patient during or following therapy, based on the presence and/or level and/or distribution of OCTs in the patient's body; and/or for determining a condition or deterring an impaired structure and/or function of OCT- expressing tissue and/or organ.

Some embodiments of the present invention also relate to quinolinium-based salts which are usable in targeting an OCT.

The compounds:

According to an aspect of some embodiments of the present invention there is provided a radiolabeled compound that is capable of targeting, as described and defined herein, an organic cation transporter such as a human organic cation transporter, as described and defined herein.

By "targeting an OCT" it is meant that the compounds have an affinity to an OCT, and can therefore interact with an OCT. This term encompasses modulation of an activity of an OCT (e.g., activating or inhibiting), interaction with an OCT by being a substrate thereof (such that an OCT facilitates influx of the compound into cells expressing the OCT), and/or simply interacting with an OCT (either chemically or physically) without affecting its activity.

Interacting with an OCT encompasses, for example, chemically interacting (e.g., via hydrogen bond(s) formation, covalent bond(s) formation and/or ionic bond(s) formation) with a portion of the OCT and/or an uptake by cells, tissue and/or organs which express an OCT.

In some embodiments, compounds that interact with an OCT have an affinity to an OCT which is reflected by a Km value of no more than 10 micromolar, or no more than 1 micromolar, or no more than 500 nM or no more than 100 nM or of a few nM. According to some of any of the embodiments described herein, the radiolabeled compound features a skeleton that resembles a skeleton of a substrate or an inhibitor of an organic cation transporter. In some embodiments, the radiolabeled compound features a skeleton that features at least some of the structural features of a substrate or an inhibitor of an organic cation transporter.

According to some of any of the embodiments described herein, the radiolabeled compound features a skeleton that resembles, or features at least some of the structural features of, an inhibitor of an organic cation transporter.

According to some of these embodiments, the inhibitor of an organic action transporter is Decynium 22 (as shown hereinabove), and the radiolabeled compound features a quinolinium salt skeleton.

According to some of any of the embodiments described herein, the radiolabeled compound features a skeleton that comprises a quinolinium salt moiety that is linked to or substituted by a substituted or unsubstituted, saturated or unsaturated, moiety, for example, an aromatic moiety (aryl) or heteroaromatic moiety (heteroaryl) or cycloalkyl or heteroalicyclic, as these moieties are defined hereinunder. According to some of any of the embodiments described herein, the radiolabeled compound features a skeleton that resembles a quinolinium salt skeleton, for example, a skeleton that comprises a quaternary ammonium salt of a nitrogen-containing heterocyclic moiety other than quinoline.

By "nitrogen-containing heterocyclic moiety" are encompassed heteroalicyclic and heteroaryl moieties, as defined herein, containing one or more nitrogen atoms within the cyclic ring. Exemplary nitrogen-containing heterocyclic moieties include, but are not limited to, imidazole, morpholine, piperidine, piperazine, oxalidine, pyrrole, oxazole, thiazole, pyrazole, pyridine, pyrimidine, isoquinoline and purine.

As used herein, the phrase "radiolabeled compound" (type specified or not) describes a compound that comprises one or more radioactive atoms, as defined herein.

The phrase "radioactive atom" describes an atom with a specific radioactivity above that of background level for that atom. It is well known, in this respect, that naturally occurring elements are present in the form of varying isotopes, some of which are radioactive isotopes. The radioactivity of the naturally occurring elements is a result of the natural distribution of these isotopes, and is commonly referred to as a background radioactive level. However, there are known methods of enriching a certain element with isotopes that are radioactive. The result of such enrichment is a population of atoms characterized by higher radioactivity than a natural population of that atom, and thus the specific radioactivity thereof is above the background level.

Thus, the radioactive atoms or radiolabeled compounds of the present embodiments have a specific radioactivity that is higher than the corresponding non-radioactive atoms or non- labeled compounds, respectively, and can therefore be used as agents for radioimaging and radiotherapy.

Furthermore, the term "non-radioactive", as used herein with respect to an atom or group, refers to an atom or a group that does not comprise a radioactive atom and thus the specific radioactivity thereof is of a background level.

The term "radioactive", as used herein with respect to an atom or a group, refers to an atom or a group that comprises a radioactive atom and therefore the specific radioactivity thereof is above the background level.

In some of any of the embodiments described herein, the radioactive atom is a radioactive carbon. In some of these embodiments, the radioactive carbon is carbon-11, which is also referred to herein as ^U C or as [ ^U C].

Any other radioactive isotopes of carbon are also contemplated. Radioactive isotopes of carbon or chemical groups comprising radioactive carbon can be commercially available, or can be generated by methods known in the art.

An exemplary method of generating carbon- 11 labeled methyl iodide is described in the Examples section that follows.

In some of any of the embodiments described herein, the radioactive atom is a radioactive halogen, for example, a radioactive fluorine, a radioactive bromine and/or a radioactive iodine.

In some of any of the embodiments described herein, the radioactive halogen is a radioactive fluorine.

In some of any of the embodiments described herein, the radioactive halogen is fluorine- 18, which is also referred to herein as 18 F, or as [F 18 ].

Fluorine- 18 radiolabeled compounds are known as useful as radioimaging agents for PET. In some of any of the embodiments described herein, the radioactive halogen is a radioactive bromine.

Exemplary radioactive bromine atoms include, but are not limited to, bromine-76 and bromine-77.

Bromine-76 radiolabeled compounds are usable in PET radioimaging.

In some of any of the embodiments described herein, the radioactive halogen is a radioactive iodine.

Exemplary radioactive iodine atoms include, but are not limited to, iodine-123, iodine- 124, and iodine- 131.

Iodine-123 radiolabeled compounds are usable in SPECT radioimaging.

Iodine- 124 radiolabeled compounds are usable in both PET radioimaging and/or radiotherapy.

Any other radioactive isotopes of fluorine, bromine and iodine are also contemplated. Radioactive isotopes of fluorine, bromine and iodine can be commercially available, or can be generated by methods known in the art.

An exemplary method of generating radioactive fluorine is described in the Examples section that follows.

According to some of any of the embodiments described herein, there are provided radiolabeled compounds featuring a quinolinium salt skeleton, which are collectively represented by Formula P:

Formula Γ wherein:

A ^" is an anion, as defined and described herein;

X is selected from hydrogen, a substituted or unsubstituted alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted aryl, a substituted or unsubstituted heteroalicyclic and R*;

m is 0 or an integer of from 1 to 3;

n is 0 or an integer of from 1 to 4;

Ri and R ₂ are each independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroalicyclic, heteroaryl, alkoxy, aryloxy, thioalkoxy, thioaryloxy, hydroxyl, halogen, trihaloalkyl, trihaloalkoxy, amine, cyano, nitro, carbonyl, thiocarbonyl, carboxylate, thioacarboxylate, amide, thioamide, carbamate, thiocarbamate, acrylate, methacrylate, acrylamide, alkaryl, aralkyl, sulfinyl, sylfonyl, sulfonate, sulfonamide, and a substituted or unsubstituted, a saturated or unsaturated hydrocarbon chain of 1 to 20 carbon atoms, optionally interrupted by one or more heteroatoms, and R*;

wherein R* is a radioactive atom or a group that comprises a radioactive atom, and provided that at least one of Ri, R ₂ and X is R*, such that the compound comprises one or more radioactive atoms.

According to these embodiments, a radiolabeled compound of Formula I* of the present embodiments can feature a radioactive atom that is or forms a part of a substituent of a carbon atom of the quinolinium salt (one or more of Ri and R ₂ ) and/or a radioactive atom that is or forms a part of a substituent of the nitrogen atom of the quinolinium salt (X).

In some embodiments, one or more of Ri and R ₂ is R*. In some of these embodiments, a radioactive atom is or forms a part of any of the groups defining Ri and R ₂ .

In some embodiments, X is R*. In some of these embodiments, a radioactive atom is or forms a part of any of the groups defining X. For example, in case a radioactive atom is a radioactive carbon, the radioactive carbon can be a carbon of any of the groups defining X.

In some exemplary embodiments, X is an alkyl, cycloalkyl, aryl or the hydrocarbon chain, as defined herein, in which one of the carbon atoms is a radioactive carbon.

In exemplary embodiments, X is alkyl, such as a lower alkyl, of 1-10, or of 1-8, or of 1-6, or of 1-5, or of 1-4, or of 1-3, or of 1-2, carbon atoms, one of the carbon atoms be a radioactive carbon as described herein.

In exemplary embodiments, X is methyl, and the carbon atom is a radioactive carbon (e.g., carbon- 11).

In some of these embodiments, the alkyl is an unsubstituted alkyl. Alternatively, the alkyl is substituted by any of the substituents defined herein.

In case a radioactive atom is a radioactive halogen, the radioactive halogen can be, for example, a substituent of an alkyl, alkenyl, alkynyl, cycloalkyl, aryl or a hydrocarbon chain defining X.

Radiolabeled compounds according to some embodiments of the present invention can be collectively represented by Formula Pa:

wherein:

L is the alkyl, alkenyl, alkynyl, cycloalkyl, aryl or the hydrocarbon chain defining X in Formula P, as defined herein;

w is 0 or a positive integer;

q is a positive integer; and

R ₃ , which represents optional other, non-radioactive, substituents of the alkyl, cycloalkyl, aryl or hydrocarbon chain, can be one or more of alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroalicyclic, heteroaryl, alkoxy, aryloxy, thioalkoxy, thioaryloxy, hydroxyl, halogen, trihaloalkyl, trihaloalkoxy, amine, cyano, nitro, carbonyl, thiocarbonyl, carboxylate, thioacarboxylate, amide, thioamide, carbamate, thiocarbamate, acrylate, methacrylate, acrylamide, alkaryl, aralkyl, sulfinyl, sylfonyl, sulfonate, sulfonamide, and a substituted or unsubstituted, a saturated or unsaturated hydrocarbon chain of 1 to 20 carbon atoms, optionally interrupted by one or more heteroatoms.

R* in Formula Pa is as defined herein for R* in Formula P.

It is to be noted that whenever a carbon atom bears hydrogen substituents, the hydrogen atoms are not shown in any of the Formulae described herein throughout.

In some of any of the embodiments of Formula Pa herein, L is an alkyl, alkenyl, alkynyl, cycloalkyl or aryl, which is substituted by the radioactive atom (e.g., a radioactive halogen). In such embodiments, R* in Formula Pa is the radioactive atom (e.g., a radioactive halogen).

In some of any of the embodiments described herein, L is an alkyl, alkenyl, alkynyl, cycloalkyl or aryl, which is substituted by a group that comprises (e.g., is substituted by) the radioactive atom (e.g., a radioactive halogen). In such embodiments, R* in Formula Pa is a group that comprises the radioactive atom (e.g., the radioactive halogen).

In some of any of these embodiments, L is alkyl, such as a lower alkyl, of 1-10, or of 1-8, or of 1-6, or of 1-5, or of 1-4, or of 1-3, or of 1-2, carbon atoms, and R* is a substituent of the alkyl.

In some of these embodiments, R* is a radioactive halogen substituting the alkyl.

In some of any of the embodiments of Formula Pa, w is 0.

In some of any of the embodiments of Formula Pa, q is 1.

In some of any of the embodiments described herein for Formula P or Pa, the radioactive atom is a radioactive halogen. In some of these embodiments, the radioactive halogen is fluorine - 18.

In some of any of the embodiments described herein for Formula P or Pa, n is 0.

In some of any of the embodiments described herein for Formula P or Pa, m are each 0. In some of any of the embodiments described herein for Formula P or Pa, n and m are each 0.

In some of any of the embodiments described herein for Formula P, R* is a hydrocarbon chain, as defined herein, which is substituted or terminated by a radioactive atom (e.g., a radioactive halogen).

Herein, the term "hydrocarbon" describes an organic moiety that includes, as its basic skeleton, a chain of carbon atoms, also referred to herein as a backbone chain, substituted mainly by hydrogen atoms. The hydrocarbon can be saturated or unsaturated, be comprised of aliphatic, alicyclic and/or aromatic moieties, and can optionally be substituted by one or more substituents (other than hydrogen).

A substituted hydrocarbon may have one or more substituents, whereby each substituent can independently be, for example, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, azide, sulfonamide, carboxy, thiocarbamate, urea, thiourea, carbamate, amide, and hydrazine, and any other substituents as described herein (for example, as defined herein for Ri and R ₂ ).

The hydrocarbon moiety can optionally be interrupted by one or more heteroatoms, including, without limitation, one or more oxygen, nitrogen (substituted or unsubstituted, as defined herein for - NR'-) and/or sulfur atoms.

In some embodiments of any of the embodiments described herein relating to a hydrocarbon chain, the hydrocarbon is not interrupted by any heteroatom, nor does it comprise heteroatoms in its backbone chain, and can be an alkylene chain, or be comprised of alkyls, cycloalkyls, aryls, alkaryls, aralkyls, alkenes and/or alkynes, as defined herein, covalently attached to one another in any order.

In some of these embodiments, the hydrocarbon chain is such that one or more of the groups composing the backbone chain, as described herein, is substituted by a radioactive halogen.

In some of these embodiments, the hydrocarbon is such that a terminal group in the backbone chain, for example, an alkyl, alkenyl or alkynyl, is substituted at its terminus by a radioactive halogen.

In some embodiments, R* in Formula Pa is or comprises an alkylene chain as defined herein.

In some embodiments, L in Formula Pa is an alkylene chain as defined herein.

The term "alkylene" describes a saturated aliphatic hydrocarbon group, as this term is defined herein. This term is also referred to herein as "alkyl".

In some embodiments, one or more carbon atoms in the alkylene chain is substituted by a radioactive halogen.

In some embodiments, the terminal carbon in the alkylene (at the distal end relative to the point of its attachment to the quinolinium ring) is substituted by a radioactive halogen.

In some embodiments, when R* is an alkylene chain, R* can be represented by (CR'R")nV*, wherein R' and R" are as defined herein, and each independently can be, for example, hydrogen, alkyl, cycloalkyl, aryl, heteroalicyclic, heteroaryl, alkoxy, aryloxy, thioalkoxy, thioaryloxy, hydroxyl, halogen, trihaloalkyl, trihaloalkoxy, amine, cyano, nitro, carbonyl, thiocarbonyl, carboxylate, thioacarboxylate, amide, thioamide, carbamate, thiocarbamate, alkaryl, aralkyl, sulfinyl, sylfonyl, sulfonate, and sulfonamide; n is an integer of from 2 to 20; and V* is the radioactive halogen.

According to these embodiments, R* is an alkylene chain that is composed of 2-20

(CR'R") units.

R' and R" in each of these units can independently be the same or different.

In some of these embodiments, in all of the CR'R" units in the alkylene chain, each of R' and R" is hydrogen. According to these embodiments, R* is an unsubstituted alkylene chain that terminates with a radioactive halogen.

When one or both of R' and R" in one of more of the CR'R" units is other than hydrogen, R* can represent a substituted alkylene chain that terminates with a radioactive halogen.

In some of these embodiments, n is an integer ranging from 1 to 10, or from 1 to 6, or from 1 to 4.

In some of these embodiments, n is 1 or 2.

In some embodiments of any of the embodiments described herein relating to R* as being or comprising a hydrocarbon chain, the hydrocarbon chain is interrupted by one or more heteroatoms.

Exemplary such hydrocarbons comprise one or more alkylene glycol groups or derivatives thereof.

As used herein, the term "alkylene glycol" describes a -[0-(CR'R")z]y- group, with R' and R" being as defined herein (and/or as defined herein for Ri and R ₂ ), and with z being an integer of from 1 to 10, preferably, from 2 to 6, more preferably 2 or 3, and y being an integer of 1 or more. Preferably R' and R" are both hydrogen. When z is 2 and y is 1, this group is ethylene glycol. When z is 3 and y is 1, this group is propylene glycol. When y is greater than 1, this group is also referred to herein as "alkylene glycol chain".

When y is greater than 4, the alkylene glycol chain is also referred to herein as poly(alkylene glycol) moiety. In some embodiments of the present invention, a poly(alkylene glycol) moiety can have from 4 to 10 alkylene glycol groups, such that y is, for example, 4 to 10.

In some embodiments, the hydrocarbon chain is or comprises one or more alkylene glycol derivatives, in which one or more of the oxygen atoms is replaced by a sulfur atom and/or a -NR'- group, as defined herein, and/or one or more of R' and R" in one or more unit is other than hydrogen. According to some of any of the embodiments described herein, R* is or comprises one or more alkylene glycol groups, as defined herein, and terminates with a radioactive halogen, as described herein, such that a radioactive halogen is attached to the alkylene glycol group or to a terminal alkylene glycol group in case where y is greater than 1. Alternatively, R' and R" in one of the one or more alkylene glycol groups is a radioactive halogen.

The number of alkylene glycol groups can range from 1 to 20, or from 1 to 10, or from 1 to 8, or from 1 to 6, or from 1 to 4, or from 1 to 3, or from 1 to 2.

When 2 or more alkylene glycol units are present, the groups can be the same or different.

For example, R' and R" in each of these groups can independently be the same or different. Alternatively, or in addition, one or more alkylene glycol groups can differ from one another when one or both of the oxygen atoms is replaced by -NR'- or -S- in one or more units.

In some embodiments, in at least one, or in all of, the alkylene glycol units, R' and R' ' are each hydrogen.

In some of these embodiments, in all of the alkylene glycol units, each of R' and R" is hydrogen.

According to some of these embodiments, R* is or comprises an unsubstituted alkylene glycol chain that terminates with a radioactive halogen.

In some embodiments, one or both of R' and R' ' in one of more of the alkylene glycol groups is other than hydrogen, and R* is or comprises a substituted alkylene glycol chain that terminates with a radioactive halogen.

In some of any of the embodiments described herein for a hydrocarbon, the hydrocarbon moiety has from 2 to 20 carbon atoms, or 2 to 10 carbon atoms, or 2 to 8 carbon atoms, or 2 to 6 carbon atoms, or 2 to 4 carbon atoms.

Alternatively, in any of the embodiments described herein for a hydrocarbon chain, the radioactive atom is a radioactive carbon, which replaces one or more the carbon atoms in the hydrocarbon chain or in a substituent thereof. In some of these embodiments, the hydrocarbon chain does not comprise a radioactive halogen.

In exemplary embodiments of this aspect of the present invention, the radiolabeled compound is: wherein A- is an anion as defined herein and R* is a radioactive halogen as defined herein. In some of these embodiments, the radioactive halogen is radioactive fluorine such as fluorine- 18. An exemplary such compound is also referred to herein as [ 18 F]-fluoroethyl quinolinium salt is represented by the formula:

wherein A- is an anion as defined herein and R* is a radioactive fluorine such as fluorine- 18.

In exemplary embodiments of this aspect of the present invention, the radiolabeled compound is:

wherein A- is an anion as defined herein, and wherein *C is a radioactive carbon such as carbon- 11. In some of any of the embodiments described herein, for any of the compounds described herein and any of the Formulae described herein, the anion, denoted as A ^" in the quaternary ammonium salt can be any stable negatively charged atom or group.

In some of any of the embodiments described herein A ^" is a conjugated base of an acid, wherein the acid can be an organic acid or an inorganic acid.

Exemplary anions include, but are not limited to, sulfonate, such as benzenesulfonate (besylate), methanesulfonate (mesylate), toluene sulfonate (tosylate), trifluoromethanesulfonate (triflate) and naphthalenesulfonate, sulfate, pyrosulfate, bisulfate, sulfite, bisulfate, nitrate, phosphate, phosphonate, metaphosphate, pyrophosphate, halide (e.g., chloride, bromide, iodide), and a carboxylate such as, but not limited to, acetate, trifluoroacetate, ascorbate, propionate, caprylate, isobutyrate, oxalate, malonate, succinate, suberate, sebacate, fumarate, maleate, mandelate, benzoate, chlorobenzoate, methylbenzoate, dinitrobenzoate, phthalate, phenylacetate, citrate, lactate, maleate, tartrate, malate, and any other carboxylate anion that is derived from a carboxylic acid.

In exemplary embodiments, A ^" is a sulfonate, which can be derived from an organic or inorganic sulfonic acid.

Exemplary such anions include, but are not limited to, benzenesulfonate, toluenesulfonate (tosylate), trifluoromethanesulfonate (triflate) and methanesulfonate (mesylate).

In exemplary embodiments, A ^" is a halide, preferably iodide.

Any other anions are contemplated.

According to some of any of the embodiments described herein, a radiolabeled compound as described herein is capable of, or is characterized as being capable of, or is usable in, targeting, as defined herein, an organic cation transporter (OCT) as described herein in any of the respective embodiments.

According to some of these embodiments, the targeting of a radiolabeled compound as described herein is reduced in the presence of an inhibitor or substrate of the OCT.

According to some of any of the embodiments described herein, the targeting of the radiolabeled compound to the OCT is manifested by cellular uptake of the compound by cells that express the OCT. Determining a cellular uptake of the radiolabeled compound can be performed using methods known in the art. An exemplary method is described in the Examples section that follows.

According to some of any of the embodiments described herein, a radiolabeled compound as described herein has an affinity to an organic cation transporter as described herein in any of the respective embodiments, whereby the affinity is characterized by, ideally, a Km value of no more than 10 micromolar, or no more than 1 micromolar, or no more than 500 nM, or no more than 100 nM, or of a few nM. The affinity of the radiolabeled compound to an OCT as defined herein can be determined by methods known in the art. An exemplary method is described in the Examples section that follows.

According to some embodiments of the present invention there are provided non- radiolabeled compounds, which are usable in targeting an OCT, or which are for use in targeting an OCT, as defined herein. In some embodiments, the OCT is as defined herein.

According to some embodiments of the present invention, non-radiolabeled compounds which are usable for targeting an OCT, are collectively represented by Formula la:

wherein:

A ^" is an anion, as defined and described herein;

m is 0 or an integer of from 1 to 3;

n is 0 or an integer of from 1 to 4;

w is 0 or a positive integer;

L is selected from an alkyl, alkaryl, alkenyl, alkynyl, aryl, heteroalicyclic, heteroaryl and a substituted or unsubstituted, a saturated or unsaturated hydrocarbon chain of 1 to 20 carbon atoms, optionally interrupted by one or more heteroatoms;

R ₃ , if present, is a substituent of said L, and is selected from alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroalicyclic, heteroaryl, alkoxy, aryloxy, thioalkoxy, thioaryloxy, hydroxyl, halogen, trihaloalkyl, trihaloalkoxy, amine, cyano, nitro, carbonyl, thiocarbonyl, carboxylate, thioacarboxylate, amide, thioamide, carbamate, thiocarbamate, acrylate, methacrylate, acrylamide, alkaryl, aralkyl, sulfinyl, sylfonyl, sulfonate, sulfonamide, and a substituted or unsubstituted, a saturated or unsaturated hydrocarbon chain of 1 to 20 carbon atoms, optionally interrupted by one or more heteroatoms; and Ri and R ₂ are each independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroalicyclic, heteroaryl, alkoxy, aryloxy, thioalkoxy, thioaryloxy, hydroxyl, halogen, trihaloalkyl, trihaloalkoxy, amine, cyano, nitro, carbonyl, thiocarbonyl, carboxylate, thioacarboxylate, amide, thioamide, carbamate, thiocarbamate, acrylate, methacrylate, acrylamide, alkaryl, aralkyl, sulfinyl, sylfonyl, sulfonate, sulfonamide, and a substituted or unsubstituted, a saturated or unsaturated hydrocarbon chain of 1 to 20 carbon atoms, optionally interrupted by one or more heteroatoms.

In some of any of the embodiments described herein for this aspect of the present invention, L is an alkyl or is a hydrocarbon chain as described herein.

In some of any of the embodiments described herein for this aspect of the present invention, L is an alkyl, and in some embodiments it is an unsubstituted alkyl, for example, a lower alkyl as defined herein. In exemplary embodiments, L is methyl.

In some of any of the embodiments described herein for this aspect of the present invention, L is an alkyl, for example, a lower alkyl as defined herein, and in some embodiments, the alkyl is substituted by one or more halogen substituents. In some embodiments, the alkyl is substituted by a fluoro substituent, and in some embodiments, the alkyl terminates by a fluoro substituent.

According to some embodiments of the present invention there is provided a compound:

wherein A ^" is an anion as described and defined herein.

Radiosynthesis:

The radiolabeled compounds as described herein are readily synthesizable, using, for example, one-step radiosyntheses.

According to an aspect of some embodiments of the present invention there is provided a process of preparing a radiolabeled compound as described herein. The process is effected by introducing a radioactive atom or a group that comprises a radioactive atom to a quinolinium salt. Routes for introduction of a radioactive atom or a group comprising same can be selected using methodologies used in the art, depending on the position and chemical nature of the radioactive atom or group.

In exemplary embodiments, where the radioactive atom is a radioactive halogen, the process is effected by reacting a compound of Formula P, in which there is a leaving group instead of the radioactive halogen, with a radioactive atom or a reagent generating same, for example, M ⁺ Z ^" , wherein M ⁺ is a cation of an alkali metal and Z ^" is a radioactive halide anion from which a radioactive atom is generated.

As used herein throughout, the phrase "leaving group" describes a labile atom, group or chemical moiety that readily undergoes detachment from an organic molecule during a chemical reaction, while the detachment is facilitated by the relative stability of the leaving atom, group or moiety thereafter. Typically, any group that is the conjugate base of a strong acid can act as a leaving group. Representative examples of suitable leaving groups according to the present invention therefore include, without limitation, carboxylate (e.g., acetate), thiocarboxylate, sulfate (e.g., tosylate, mesylate), sulfonate (e.g., triflate), sulfinate, thiosulfate, thio sulfonate, thiosulfinate, sulfoxide, alkoxy, halogen (preferably bromo or iodo), amine, sulfonamide, carbamate, thiocarbamate, azide, phosphonyl, phopshinyl, phosphate, cyanate, thiocyanate, nitro and cyano, as these terms are defined herein.

In some embodiments, the leaving group that is replaced by the radioactive atom forms that A ^" anion in the salt.

For any of the embodiments described herein, a radioactive halide of choice, e.g., [ 18 F] ^" ,

[ 76 Br] ^" , [ 77 Br] ^" , [ 123 I] , [ 124 I] ^" or [ 131 I] ^" , can be generated by methods known in the art, or can be purchased from known vendors, either per se, or as a reagent generating same (for example, M ⁺ Z ^" , as described herein).

Exemplary radiosyntheses are described in detail in the Examples section that follows.

Radioimaging:

The radiolabeled compounds herein described can be used as radioimaging agents. Fluorine- 18 labeled, carbon- 11 labeled, bromine-76 labeled and iodine- 124 labeled compounds of the present embodiments can be used as biomarkers for PET radioimaging, whereas iodine - 123 labeled compounds of the present embodiments, can be used as biomarkers for SPECT radioimaging.

Thus, according to some of any of the embodiments of the present invention, the radiolabeled compounds as described herein are for use in radioimaging, or in a method of radioimaging, or as radioimaging agents. According to some of any of the embodiments of the present invention, the radiolabeled compounds as described herein are for use in the manufacture of a radioimaging agent. The radioimaging agent is for use in a method of radioimaging as described herein.

According to an aspect of some embodiments of the present invention there is provided a method radioimaging which comprises administering to a patient in need thereof a radiolabeled compound that targets an organic cation transporter and employing a suitable nuclear imaging technique, such as positron emission tomography or single photon emission computed tomography, for monitoring a presence and/or a level and/or a distribution and/or a distribution rate of the radiolabeled compound within the body or within a portion thereof.

Herein and in the art, an "organic cation transporter", abbreviated as OCT, describes an organic cation transporter of the solute carrier SLC22A family, as described herein and in the art, which facilitates the intracellular uptake of a broad range of structurally diverse, small organic cations.

In some of any of the embodiments described herein, the organic cation transporter is a human OCT (hOCT), and encompasses currently identified human OCT isoforms such as, but not limited to, OCTl, which is encoded by SLC22A1; OCT2, which is encoded by SLC22A2; and OCT3, which is encoded by SLC22A3.

Any OCT that can be expressed in a subject as defined herein, e.g., a human being, is contemplated.

A radiolabeled compound that targets OCT can be any compound that interacts with

OCT, as described hereinabove. The targeting of an OCT can be determined by cellular uptake of the radiolabeled compound and/or by its affinity to the OCT and/or by an effect of a known substrate or inhibitor of the OCT on the cellular uptake of the radiolabeled compound.

According to some of any of the embodiments of the present invention, the radioimaging is effected by administering to the patient a radiolabeled compound and employing a suitable nuclear imaging technique, such as positron emission tomography or single photon emission computed tomography, for monitoring a presence and/or level and/or distribution and/or the distribution rate of the radiolabeled compound within the body or within a portion thereof.

In some embodiments of this aspect of the present invention, the radiolabeled compound is a fluorine- 18, carbon- 11, bromine-76, iodine- 123 or iodine- 124 radiolabeled compound.

In some embodiments of this aspect of the present invention, the radiolabeled compound is a fluorine- 18, carbon- 11, bromine-76, iodine- 123 or iodine- 124 radiolabeled compound as described herein in any of the respective embodiments, or any other radiolabeled compound that comprises a radioactive atom suitable for nuclear imaging and is capable of targeting an OCT as defined herein.

According to an aspect of some embodiments of the present invention there is provided a method of radioimaging, which comprises administering to the patient any of, for example, the fluorine- 18, carbon-11, bromine-76, iodine- 123 or iodine- 124 radiolabeled compounds as described herein in any of the respective embodiments and employing a suitable nuclear imaging technique, such as positron emission tomography or single photon emission computed tomography, for monitoring a presence and/or level and/or distribution and/or distribution rate of the radiolabeled compound within the body or within a portion thereof.

Nuclear imaging dosing depends on the affinity of the compound to its target, the isotope employed and the specific activity of labeling. Persons ordinarily skilled in the art can easily determine optimum nuclear imaging dosages and dosing methodology.

In some embodiments, a radioimaging method as described herein is useful for monitoring or determining a presence and/or level and/or distribution of an OCT within the body of the patient.

The radiolabeled compounds as described herein are preferably characterized by at least a moderate affinity to OCT. Cells, tissues or organs which feature an increased expression of OCT are therefore assumed to result in a higher uptake of the radiolabeled compounds of the present embodiments, compared to those which do not feature overexpression of OCT, such that an accumulation (presence and level) of the radiolabeled compound at certain cells, tissues and or organs of a patient (distribution) is indicative of an increased expression of OCT in these cells.

In some embodiments, the presence and/or level and/or distribution of the radiolabeled compound in the patient's body or a portion thereof is indicative of subject's medical condition in case this condition is associated with deregulated expression and/or activity of an OCT; and/or is treatable by modulating an expression and/or activity of an OCT; and/or is treatable by an agent that exploits an expression and/or activity of an OCT.

In some of these embodiments, the radioimaging is for determining if the patient has a disease or disorder that is treatable by modulating an expression and/or activity of an organic cation transporter.

Such a radioimaging is useful for determining if the patient suffers from a disease or disorder that is associated with deregulated activity and/or expression of an OCT and/or which is treatable by modulating an activity of an OCT. Herein, the phrase "deregulated activity and/or expression" of an OCT describes aberrant, or abnormal, activity and/or expression of OCT, for example, overexpression of OCT, overactivity of OCT or reduced activity of OCT.

According to some of any of the embodiments described herein, the radioimaging is for determining if the patient has a disease or disorder treatable by an agent that modulates the expression and/or activity of an OCT.

According to some of any of the embodiments described herein, the radioimaging is for determining if the patient has a disease or disorder treatable by an agent that modulates an activity of an OCT, for example by an inhibitor, an activator or a substrate of an OCT.

According to some of any of the embodiments described herein, the radioimaging is for determining if the patient is responsive to a treatment with an agent that modulates an activity and/or expression of an OCT.

According to some of any of the embodiments described herein, the patient is diagnosed as having a disease or disorder associated with deregulated expression and/or activity of OCT, and the radioimaging is for determining if the patient should be treated with an agent that modulates an activity and/or expression of an OCT.

Any agents that modulate an activity and/or expression of an OCT, such as, for example, inhibitors, activators and substrates of OCTs (e.g., hOCTs) known in the art are contemplated herein.

According to an aspect of some embodiments of the present invention there is provided a method of radioimaging, or a use of the radiolabeled compounds as described herein in radioimaging, as described herein, and the radioimaging is for determining if a patient is responsive to a treatment with an agent that modulates an activity of an OCT.

In some embodiments, such a method is suitable for determining a first-line therapy for a patient who is diagnosed as having, or as suspected of having, a disease or disorder associated with deregulated expression and/or activity of OCT.

According to some embodiments, the radioimaging is for determining if the patient has a disease or disorder that is treatable by exploiting an expression and/or activity of an organic cation transporter.

Such a radioimaging is useful for determining if the patient suffers from a disease or disorder that is treatable by exploiting an expression and/or an activity of an OCT.

According to some of any of the embodiments described herein, the radioimaging is for determining if the patient has a disease or disorder treatable by an agent that interacts (e.g., taken up) with an OCT, as defined herein, for example, a therapeutically active agent (drug) that is positively charged and its intracellular accumulation is effected by an expression and/or activity of OCT (e.g., in a certain cell, tissue or organ).

According to some of any of the embodiments described herein, the radioimaging is for determining if the patient is responsive to a treatment with an agent that exploits an activity and/or expression of an OCT.

According to some of any of the embodiments described herein, the radioimaging is for determining if the patient is responsive to a treatment with an agent that interacts with an OCT (e.g., taken up by an OCT).

Any agents that interact with an OCT, as defined herein, are contemplated herein.

According to an aspect of some embodiments of the present invention there is provided a method of radioimaging, or a use of the radiolabeled compounds as described herein in radioimaging, as described herein, and the radioimaging is for determining if a patient is responsive to a treatment with an agent that exploits an activity of an OCT, as described herein.

In some embodiments, the presence and/or level and/or distribution of the radiolabeled compound in the patient's body or a portion thereof is indicative of the responsiveness of the patient's to a therapy whose efficacy correlates with a presence and/or level of an organic cation transporter.

In some embodiments, the radioimaging is for determining if the patient has a disease or disorder that is treatable by or responsive to a therapy whose efficacy correlates with a presence and/or level and/or distribution of an organic cation transporter.

In some embodiments, the patient is diagnosed as having, or as suspected of having, a disease or disorder that is treatable by or responsive to a therapy whose efficacy correlates with a presence and/or level and/or distribution of an organic cation transporter and the radioimaging is for determining if the disease or disorder is treatable by the therapy.

In some embodiments, a therapy that correlates with a presence and/or level and/or distribution of an organic cation transporter encompasses a therapy that comprises, or consists of, administration of a therapeutically active agent (drug) and its efficacy depends on a level of intracellular accumulation of the drug, at least to certain cells.

In some embodiments, the radioimaging is performed following the therapy, and is for determining a responsiveness or an emergence of a resistance to the therapy.

In some of any of the embodiments described herein, the disease or disorder is a proliferative disease or disorder.

In some of any of the embodiments described herein, the patient is diagnosed as having, or as suspected of having, a proliferative disease or disorder such as cancer. In some of any of the embodiments described herein, a patient is diagnosed, or is suspected to be diagnosed, with the indicated disease or disorder, by means known in the art, such as, for example, imaging methods such as computed tomography (CT), MRI, X-ray imaging, and/or by means of biopsy, determination of biomarkers in blood samples, etc.

In some of these embodiments, the radioimaging is for determining and/or monitoring a presence and/or level and/or distribution of an organic cation transporter in a tumor cell or tissue within the body of the patient.

As used herein, the terms "cancer" and "tumor" are interchangeably used. The terms refer to a malignant growth and/or tumor caused by abnormal and uncontrolled cell proliferation (cell division). The term "cancer" encompasses tumor metastases.

The term "cancer cells" describes the cells forming the malignant growth or tumor.

Non-limiting examples of cancers and/or tumor metastases preferably include solid cancer and/or tumor metastasis, including, but not limiting to, tumors of the gastrointestinal tract (e.g., colon carcinoma, rectal carcinoma, colorectal carcinoma, colorectal cancer, colorectal adenoma, hereditary nonpolyposis type 1, hereditary nonpolyposis type 2, hereditary nonpolyposis type 3, hereditary nonpolyposis type 6; colorectal cancer, hereditary nonpolyposis type 7, small and/or large bowel carcinoma, esophageal carcinoma, tylosis with esophageal cancer, stomach carcinoma, pancreatic carcinoma, pancreatic endocrine tumors), endometrial carcinoma, dermatofibro sarcoma protuberans, gallbladder carcinoma, biliary tract tumors, prostate cancer, prostate adenocarcinoma, renal cancer (e.g., Wilms' tumor type 2 or type 1), liver cancer (e.g., hepatoblastoma, hepatocellular carcinoma, hepatocellular cancer), bladder cancer, embryonal rhabdomyosarcoma, germ cell tumor, trophoblastic tumor, testicular germ cells tumor, immature teratoma of ovary, uterine, epithelial ovarian, sacrococcygeal tumor, choriocarcinoma, placental site trophoblastic tumor, epithelial adult tumor, ovarian carcinoma, serous ovarian cancer, ovarian sex cord tumors, cervical carcinoma, uterine cervix carcinoma, small-cell and non-small cell lung carcinoma, nasopharyngeal, breast carcinoma (e.g., ductal breast cancer, invasive intraductal breast cancer, sporadic breast cancer, susceptibility to breast cancer, type 4 breast cancer, breast cancer-1, breast cancer-3, breast-ovarian cancer), squamous cell carcinoma (e.g., in head and neck), neurogenic tumor, astrocytoma, ganglioblastoma, neuroblastoma, lymphomas (e.g., Hodgkin's disease, non-Hodgkin's lymphoma, B-cell lymphoma, Diffuse large B-cell lymphoma (DLBCL), Burkitt lymphoma, cutaneous T-cell lymphoma, histiocytic lymphoma, lymphoblastic lymphoma, T-cell lymphoma, thymic lymphoma), gliomas, adenocarcinoma, adrenal tumor, hereditary adrenocortical carcinoma, brain malignancy (tumor), various other carcinomas (e.g., bronchogenic large cell, ductal, Ehrlich-Lettre ascites, epidermoid, large cell, Lewis lung, medullary, mucoepidermoid, oat cell, small cell, spindle cell, spinocellular, transitional cell, undifferentiated, carcinosarcoma, choriocarcinoma, cystadenocarcinoma), ependimoblastoma, epithelioma, fibrosarcoma, giant cell tumor, glial tumor, glioblastoma (e.g., multiforme, astrocytoma), glioma hepatoma, heterohybridoma, heteromyeloma, histiocytoma, hybridoma (e.g., B-cell), hypernephroma, insulinoma, islet tumor, keratoma, leiomyoblastoma, leiomyosarcoma, lymphosarcoma, mammary tumor, mastocytoma, medulloblastoma, mesothelioma, metastatic tumor, monocyte tumor, multiple myeloma, myelodysplastic syndrome, myeloma, nephroblastoma, nervous tissue glial tumor, nervous tissue neuronal tumor, neurinoma, neuroblastoma, oligodendroglioma, osteochondroma, osteomyeloma, osteosarcoma (e.g., Ewing's), papilloma, transitional cell, pheochromocytoma, pituitary tumor (invasive), plasmacytoma, retinoblastoma, rhabdomyosarcoma, sarcoma (e.g., Ewing's, histiocytic cell, Jensen, osteogenic, reticulum cell), schwannoma, subcutaneous tumor, teratocarcinoma (e.g., pluripotent), teratoma, testicular tumor, thymoma and trichoepithelioma, gastric cancer, fibrosarcoma, glioblastoma multiforme, multiple glomus tumors, Li-Fraumeni syndrome, liposarcoma, lynch cancer family syndrome II, male germ cell tumor, medullary thyroid, multiple meningioma, endocrine neoplasia myxosarcoma, paraganglioma, familial nonchromaffin, pilomatricoma, papillary, familial and sporadic, rhabdoid predisposition syndrome, familial, rhabdoid tumors, soft tissue sarcoma, and Turcot syndrome with glioblastoma.

In some embodiments, the proliferative disease or disorder is a colorectal cancer (CRC). In some embodiments, the proliferative disease or disorder is metastatic CRC.

In some embodiments, the proliferative disease or disorder is a cancer for which a first- line or second-line therapy comprises a platinum-based chemotherapy.

As discussed hereinabove, the present inventors have recognized that since OCTs affect the cellular accumulation of platinum-based drugs, determining a presence and/or level and/or distribution of OCTs in, for example, tumor cells, can be beneficially used for devising a treatment strategy, for monitoring treatment, for predicting an outcome of a treatment, and for identifying resistance to treatment.

In some of any of the embodiments described herein, a therapy whose efficacy that correlates with a presence and/or level of OCT in the tumor cells is a therapy comprises a platinum-based chemotherapy.

The therapy can consist of a platinum-based chemotherapy, or can comprise a platinum- based chemotherapy in combination with other chemotherapies and/or other therapeutic methodologies (e.g., surgery, immunotherapy, etc.). Platinum-based chemotherapy encompasses administration of one or more platinum- based drugs, including, for example, cisplatin, carboplatin and oxaliplatin.

In some embodiments, the platinum-based chemotherapy comprises administration of oxaliplatin.

In some of any of the embodiments described herein, the radioimaging is for monitoring or determining a presence and/or level of OCT in a patient that has been diagnosed as having a cancer for which a first- line or second-line therapy comprises a platinum-base chemotherapy.

According to an aspect of some embodiments of the present invention there is provided a method of radioimaging, or a use of the radiolabeled compounds as described herein in radioimaging, or as radioimaging agents, as described herein, and the radioimaging is for monitoring or determining a presence and/or level of OCT in a patient that has been diagnosed as having a cancer for which a first-line or second-line therapy comprises a platinum-base chemotherapy.

In some of these embodiments, the patient is diagnosed (or is suspected to be diagnosed) with such a cancer, and the radioimaging is used for determining a suitable treatment for this patient.

In some embodiments, a presence and/or level and/or distribution of the radiolabeled compound in the patient's body or the portion thereof is indicative of a presence and/or level and/or distribution of OCT which confers sensitivity to a therapy as described herein.

In some embodiments, an absence of the compound in the tumor cells or tissue in the patient's body is indicative of cancer cells that do not express OCT, and suggests of a reduced sensitivity of the cancer cells to platinum-based chemotherapy, or of a resistance to platinum- based chemotherapy.

The radiolabeled compounds as described herein are therefore useful for determining if a patient has OCT-expressing tumor cells which confer sensitivity and responsiveness to a therapy that comprises platinum-based chemotherapy.

In some embodiments, based on a presence and/or level and/or distribution of the radiolabeled compound, the presence or absence of OCT-expressing tumor cells is determined and therapy that is suitable for treating the cancer is determined accordingly, as described herein.

In some embodiments, the presence and/or level and/or distribution of the radiolabeled compound is indicative of a presence and/or level and/or distribution of OCT-expressing cancer cells, which in turn confers sensitivity to a therapy that comprises platinum-based chemotherapy, and hence of a patient being responsive to such a therapy. In some embodiments, the radioimaging is performed following a therapy as described herein (e.g., a therapy that comprises platinum-based chemotherapy), and is for determining an emergence of a resistance to the therapy.

In some embodiments, an absence of the radiolabeled compound in the patient's body or a portion thereof (no uptake of the compound in a patient's body or a portion thereof) (e.g., following the therapy) is indicative of insensitivity (non-responsiveness) or resistance to the therapy.

In some of any of the embodiments described herein, a method of radioimaging as described herein in any of the respective embodiments, is useful in the course of treatment of a patient diagnosed with a disease or disorder which is treatable by a therapy whose efficacy correlates to a level and/or presence of an organic cation transporter, as described herein.

According to an aspect of some embodiments of the present invention there is provided a method of treating a patient diagnosed with a disease or disorder which is treatable by a therapy whose efficacy correlates to a level and/or presence of an organic cation transporter, as described herein.

According to some embodiments of this aspects of the present invention, the treatment comprises:

administering the radiolabeled compound to the patient;

determining a presence and/or level of the radiolabeled compound in the patient's body or a portion thereof by employing a nuclear imaging technique, as described herein, wherein the presence and/or level being indicative of the patient's responsiveness to the therapy; and

based on the determining, subjecting the patient to the therapy or to a different therapy.

In some of these embodiments, following the determination, the patient is identified as responsive to the therapy, as described herein, and is subjected to the therapy.

Alternatively, the patient is indentified as non-responsive to the therapy and is subjected to another therapy of choice.

In some embodiments, the patient is identified as responsive to the therapy, as described herein, and is subjected to the therapy for a first time period, and, following the first time period, a responsiveness or an emergence of a resistance to the therapy is determined by:

administering the radiolabeled compound to the patient;

determining a presence and/or level of the radiolabeled compound in the patient's body or the portion thereof by employing the nuclear imaging technique (second radioimaging), the presence and/or level being indicative of the patient's responsiveness to the therapy; and based on the determining, subjecting the patient to the therapy for a second time period or subjecting the patient to a different therapy for the second time period.

The second radioimaging is preferably the same as the first radioimaging.

Based on the second radioimaging, the patient is subjected to the therapy for an additional (second) time period, if it is determined that that the patient is still responsive to the therapy, or is subjected to another therapy of choice for the second time period, namely, the treatment is replaced.

The radioimaging can be repeated following the second time period, and following additional time periods, as long as it is determined that the patient remains responsive to the therapy.

Such embodiments relate to a method of treating a disease or disorder as described herein, while selecting a therapy of choice and while optionally longitudinally monitoring the therapy's efficiency, namely monitoring the patient's responsiveness to the therapy.

In some embodiments, using a method of treatment as described herein, the radioimaging performed following the first time period can provide information on the treatment efficacy, and can be used for determining the therapy of choice in the second treatment period.

The treatment described herein therefore provides immediate indication of the treatment efficacy, and hence immediate personalized adjustment of the therapy during treatment. In some of any of the embodiments described herein, in addition to the radioimaging, other diagnosis measures are applied, such as biopsy, as complementary measures for verifying, supporting, and/or providing further information on top of, the radioimaging findings.

According to some of any of the embodiments described herein, the method as described herein is for radioimaging OCT-expressing cells, tissues and/or organs, while exploiting an uptake of a radiolabeled compound by these cells, tissues and/or organs for gaining an information of a presence or absence of a medical condition that is associated with impaired function and/or structure of these cells, tissues and/or organs.

According to some of any of the embodiments described herein for radioimaging, the radioimaging is of an OCT-expressing cell, tissue and/or organ and is for determining if the patient has, or is prone or predisposed to have, an impaired function and/or structure of the cell, tissue and/or organ.

According to some of any of the embodiments described herein for radioimaging, the radioimaging is of an OCT-expressing cell, tissue and/or organ and is for determining if the patient has, or is prone or predisposed to have, a disease or disorder that is associated with impaired function and/or structure of the cell, tissue and/or organ. In some of any of these embodiments, the OCT-expressing cell, tissue and/or organ is of the cardiovascular system. In some embodiments it is a cardiac or myocardial cell and/or tissue, and is some embodiments it is the heart muscle or a portion thereof (e.g., a left ventricle, a right ventricle, a right auricle, a left auricle). In some embodiments, it is the left ventricle (LV).

In some of any of these embodiments, the OCT-expressing cell, tissue and/or organ is of the cardiovascular system, as described herein, and the radioimaging is for determining if a patient has, or is prone or predisposed to have, an impaired function and/or structure of the cardiovascular system, for example, an impaired cardiac function or impaired myocardial blood perfusion.

In some of any of these embodiments, the OCT-expressing cell, tissue and/or organ is of the cardiovascular system, as described herein, and the radioimaging is for determining of a patient has, or is prone or predisposed to have, a cardiovascular disease or disorder or cardiac disease or disorder.

Cardiovascular diseases and disorders include, but are not limited to, atherosclerosis, a cardiac valvular disease, coronary stenosis, restenosis, in-stent-stenosis, myocardial infarction, coronary arterial disease (CAD), acute coronary syndromes, congestive heart failure, angina pectoris, myocardial ischemia, thrombosis, Wegener's granulomatosis, Takayasu's arteritis, Kawasaki syndrome, anti-factor VIII autoimmune disease or disorder, necrotizing small vessel vasculitis, microscopic polyangiitis, Churg and Strauss syndrome, pauci-immune focal necrotizing glomerulonephritis, crescentic glomerulonephritis, antiphospholipid syndrome, antibody induced heart failure, thrombocytopenic purpura, autoimmune hemolytic anemia, cardiac autoimmunity, Chagas' disease or disorder, and anti-helper T lymphocyte autoimmunity.

In addition to the above, cardiac diseases or disorders include cardiac arrhythmi, and medical conditions associated with cardiac arrhythmia.

The cardiac arrhythmia can be a ventricular arrhythmia, an atrial arrhythmia, a junctional arrhythmia and a heart block.

Medical conditions associated with atrial arrhythmia include, but are not limited to, Premature atrial contractions (PACs), Wandering atrial pacemaker, Atrial tachycardia, Multifocal atrial tachycardia, Supraventricular tachycardia (SVT), Atrial flutter, and Atrial fibrillation (Afib).

Medical conditions associated with junctional arrhythmia include, but are not limited to, AV nodal reentrant tachycardia, Junctional rhythm, Junctional tachycardia, and Premature junctional contraction. Medical conditions associated with ventricular arrhythmia include, but are not limited to, Premature ventricular contractions (PVCs), sometimes called ventricular extra beats (VEBs), Premature ventricular beats occurring after every normal beat are termed "ventricular bigeminy", Accelerated idioventricular rhythm, Monomorphic ventricular tachycardia, Polymorphic ventricular tachycardia, Ventricular fibrillation, and Torsades de pointes.

Medical conditions associated with heart block include, but are not limited to, AV heart blocks, which arise from pathology at the atrioventricular node, including First degree heart block, which manifests as PR prolongation, Second degree heart block, including Type 1 Second degree heart block, also known as Mobitz I or Wenckebach, and Type 2 Second degree heart block, also known as Mobitz II, and Third degree heart block, also known as complete heart block.

Exemplary medical conditions associated with cardiac arrhythmia include, but are not limited to, atrial fibrillation, ventricular fibrillation, conduction disorders, premature contraction, and tachycardia.

Conduction disorders collectively encompass abnormal or irregular progression of electrical pulses through the heart, which cause a change in the heart rhythm. Conductions disorders are not necessarily associated with arrhythmia but sometimes are the cause of arrhythmia. Exemplary conductions disorders include, but are not limited to, Bundle Branch Block, heart block, including first-, second- and third-degree heart block, and long Q-T syndrome.

Premature contraction includes premature atrial contractions and premature ventricular contractions.

Additional exemplary medical conditions associated with arrhythmia include Adams- Stokes Disease (also called Stokes-Adams or Morgangni), atrial flutter, which is usually found in patients with: Heart failure, Previous heart attack, Valve abnormalities or congenital defects, High blood pressure, Recent surgery, Thyroid dysfunction, Alcoholism (especially binge drinking), Chronic lung disease, Acute (serious) illness, Diabetes, after open-heart surgery (bypass surgery), or atrial fibrillation; Sick Sinus syndrome; sinus arrhythmia and Wolff- Parkinson-White (WPW) syndrome.

The cardiac arrhythmia can include tachycardia, and encompasses atrial and

Supraventricular tachycardia (SVT), including paroxysmal atrial tachycardia (PAT) or paroxysmal supraventricular tachycardia (PSVT); Sinus tachycardia, which can be associated with disorders of that heart which interfere with the normal conduction system of the heart, including, but not limited to, Lack of oxygen to areas of the heart due to lack of coronary artery blood flow, Cardiomyopathy in which the structure of the heart becomes distorted, Medications, Illicit drugs such as cocaine, and Sarcoidosis (an inflammatory disease affecting skin or other body tissues).

The tachycardia can be a ventricular tachycardia, a supraventricular tachycardia, atrial fibrillation, AV nodal reentrant tachycardia (AVNRT), or a AV reentrant tachycardia (AVRT).

Additional cardiac diseases and disorders include CPVT, long QT syndrome, bradycardia and diseases and disorders associated with bradycardia.

In some of any of the embodiments described herein, the radioimaging is a myocardial perfusion imaging (MPI), which is for determining a function of the heart, its structure and/or blood perfusion into the heart.

Myocardial perfusion imaging is currently the most common tool for non-invasively evaluating ischemia in patients with suspected coronary artery disease (CAD). This technique contributes substantially to the risk- stratification of CAD patients, in terms of their likelihood to encounter myocardial or coronary events such as myocardial infarction, myocardial ischemia, coronary aneurysm, wall motion abnormalities; to the assessment of a viable myocardium following a coronary event when revascularization is considered; and to an assessment of the myocardium following intervening revascularization (e.g., coronary artery bypass graft, angioplasty).

Therefore, MPI provides valuable information which assists clinical decision-making with regard to medical treatment and intervention. Typically, MPI is used for the assessment and comparison of left ventricular function during both post-stress and rest conditions, and is done in conjunction with cardiac stress test.

In some of any of the embodiments described herein, the radioimaging (MPI) is for use in the prognosis and risk stratification of a cardiac disease in patients with known or suspected cardiovascular or cardiac disease or disorder as described herein (e.g., CAD).

In some of any of the embodiments described herein, the radioimaging (MPI) is for use in the prediction of functional recovery following acute myocardial infarction.

In some of any of the embodiments described herein, the radioimaging (MPI) is for use in in the prediction of functional recovery after revascularization in patients with chronic ischemic left ventricle (LV) dysfunction.

In some embodiments, an additional noninvasive imaging modality (e.g. stress echocardiography; radioimaging with other agents; other imaging methods) is used sequentially or concurrently with the radioimaging.

In some of any of the embodiments described herein, the radioimaging (e.g., MPI) is for determining a blood flow to the heart muscle, for determining the effects of a heart attack, or myocardial infarction, on areas of the heart, for identifying areas of the heart muscle that would benefit from a procedure such as angioplasty or coronary artery bypass surgery (in combination with a myocardial perfusion scan) or for mapping a normal heart function.

In some of any of the embodiments described in the context of this aspect of these embodiments, the patient suffers from, or has predisposition to suffer from, or has symptoms which may be associated with, a disease or disorder as described herein (e.g., a cardiac or cardiovascular disease or disorder as described herein).

In some of any of the embodiments described herein, the radioimaging is performed following subjecting the patient to a therapy of the disease or disorder (associated with impaired structure and/or or function of OCT-expressing cell, tissue or organ), and is for monitoring the patient's responsiveness to the therapy and/or for monitoring the efficacy of the therapy.

According to an aspect of some embodiments of the present invention there is provided a method of diagnosing a patient that suffers or is prone to suffer from a disease or disorder associated with an impaired function and/or structure of an OCT-expressing cell, tissue or organ in a patient (a subject in need thereof). The method is effected by:

subjecting the patient to a radioimaging as described herein, to thereby determine an imaging parameter of the OCT-expressing cell, tissue or organ; and

determining, based on the imaging parameter, a presence and/or severity of the impaired structure and/or function.

According to an aspect of some embodiments of the present invention there is provided a method of treating a disease or disorder associated with an impaired function and/or structure of an OCT-expressing cell, tissue or organ in a patient (a subject in need thereof). The method is effected by:

subjecting the patient to a first radioimaging, to thereby determine an imaging parameter of the OCT-expressing cell, tissue or organ;

determining, based on the imaging parameter, a severity of the disease or disorder (e.g., an extent of impaired structure and/or function of the cell, tissue or organ); and

based on determining the severity of the disease or disorder, subjecting the patient to a therapy for treating the disease or disorder.

In some embodiments, the imaging parameter is compared with a control reference that correlates with the severity of the disease or disorder, wherein the comparison allows for determining of the severity of the disease or disorder in the subject.

In some embodiments, the method further comprises monitoring the efficacy of the therapy, following a first time period of the therapy, by: Subjecting the patient to a second radioimaging (which is preferably the same as the first radioimaging), to thereby determine the same imaging parameter of the OCT-expressing cell, tissue or organ;

determining, based on the imaging parameter, a severity of the disease or disorder (e.g., an extent of impaired structure and/or function of the cell, tissue or organ); and

based on determining the severity of the disease or disorder, subjecting the patient to the therapy for treating the disease or disorder for a second time period or to a different therapy.

In some embodiments, the imaging parameter is compared with the imaging parameter obtained in the first radioimaging, wherein the comparison allows determining the efficacy of the therapy.

The therapy can comprise a drug therapy, or an intervening therapy (e.g., surgery, angioplasty, etc.).

As used herein, the term "imaging parameter" refers to any parameter which can be measured using the radioimaging, including, but are not limited to, images (e.g. four-dimensional images or pictures of functional processes in the body) acquired by the radioimaging.

In some embodiments, the radioimaging is MPI, and the imaging parameter includes, for example, one or more of images which correlate with myocardial vascular resistance, the extent of blood supply to the heart muscle (e.g. pointing to inadequate blood supply in specific regions of the heart), information about the heart's pumping function, the amount of scarring from a heart attack, the success of coronary bypass surgery or angioplasty. In some embodiments, the imaging parameter is a presence and/or level and/or distribution and/or distribution rate of the radiolabeled compound in the patient's body or a part thereof.

In some of any of the embodiments described herein for radioimaging, the radioimaging further comprises, prior to administering the radiolabeled compound to a patient, preparing the radiolabeled compound.

In some of these embodiments, the radiolabeled compound is prepared as described herein in any of the respective embodiments and any combination thereof.

In some of these embodiments, the radiolabeled compound is prepared 1, 2, 3 or even more hours before being administered to the patient, depending on the radioactive atom used (and its half life).

Pharmaceutical compositions:

Any of the radiolabeled compounds described herein can be formulated into a pharmaceutical composition which can be used for radiotherapy of a disease or for imaging, as described herein in any of the methods and uses and respective embodiments thereof. Such a composition includes as an active ingredient any of the radiolabeled compounds described herein and a pharmaceutically acceptable carrier.

As used herein a "pharmaceutical composition" refers to a preparation of one or more of the radiolabeled compounds described herein, with other chemical components such as pharmaceutically suitable carriers and excipients. The purpose of a pharmaceutical composition is to facilitate administration of a compound to an organism.

Hereinafter, the term "pharmaceutically acceptable carrier" refers to a carrier or a diluent that does not cause significant irritation to an organism and does not abrogate the biological activity and properties of the administered compound. Examples, without limitations, of carriers are: propylene glycol, saline, emulsions and mixtures of organic solvents with water.

Herein the term "excipient" refers to an inert substance added to a pharmaceutical composition to further facilitate administration of a compound. Examples, without limitation, of excipients include calcium carbonate, calcium phosphate, various sugars and types of starch, cellulose derivatives, gelatin, vegetable oils and polyethylene glycols.

Techniques for formulation and administration of drugs may be found in "Remington's

Pharmaceutical Sciences," Mack Publishing Co., Easton, PA, latest edition.

Suitable routes of administration may, for example, include intravenous, intraperitoneal, intranasal, or intraocular injections, oral, rectal, transmucosal, especially transnasal, intestinal or parenteral delivery, including intramuscular, subcutaneous and intramedullary injections as well as intrathecal, direct intraventricular, intracardiac, e.g., into the right or left ventricular cavity, or into the common coronary artery.

Alternately, one may administer the pharmaceutical composition in a local rather than systemic manner, for example, via injection of the pharmaceutical composition directly into a tissue region of a patient.

The term "tissue" refers to part of an organism consisting of cells designed to perform a function or functions. Examples include, but are not limited to, pulmonary tissue, pancreatic tissue, brain tissue, retina, skin tissue, hepatic tissue, breast tissue, bone, cartilage, connective tissue, blood tissue, muscle tissue, cardiac tissue, vascular tissue, renal tissue, gonadal tissue, rectal tissue, and hematopoietic tissue.

Pharmaceutical compositions of some embodiments of the invention may be manufactured by processes well known in the art, e.g., by means of conventional mixing, dissolving, granulating, dragee-making, levigating, emulsifying, encapsulating, entrapping or lyophilizing processes. Pharmaceutical compositions for use in accordance with some embodiments of the invention thus may be formulated in conventional manner using one or more physiologically acceptable carriers comprising excipients and auxiliaries, which facilitate processing of the active ingredients into preparations which, can be used pharmaceutically. Proper formulation is dependent upon the route of administration chosen.

For injection, the active ingredients of the pharmaceutical composition may be formulated in aqueous solutions, preferably in physiologically compatible buffers such as Hank's solution, Ringer's solution, or physiological salt buffer. For transmucosal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art.

For oral administration, the pharmaceutical composition can be formulated readily by combining the active compounds with pharmaceutically acceptable carriers well known in the art. Such carriers enable the pharmaceutical composition to be formulated as tablets, pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions, and the like, for oral ingestion by a patient. Pharmacological preparations for oral use can be made using a solid excipient, optionally grinding the resulting mixture, and processing the mixture of granules, after adding suitable auxiliaries if desired, to obtain tablets or dragee cores. Suitable excipients are, in particular, fillers such as sugars, including lactose, sucrose, mannitol, or sorbitol; cellulose preparations such as, for example, maize starch, wheat starch, rice starch, potato starch, gelatin, gum tragacanth, methyl cellulose, hydroxypropylmethyl-cellulose, sodium carboxymethylcellulose; and/or physiologically acceptable polymers such as polyvinylpyrrolidone (PVP). If desired, disintegrating agents may be added, such as cross- linked polyvinyl pyrrolidone, agar, or alginic acid or a salt thereof such as sodium alginate.

Dragee cores are provided with suitable coatings. For this purpose, concentrated sugar solutions may be used which may optionally contain gum arabic, talc, polyvinyl pyrrolidone, carbopol gel, polyethylene glycol, titanium dioxide, lacquer solutions and suitable organic solvents or solvent mixtures. Dyestuffs or pigments may be added to the tablets or dragee coatings for identification or to characterize different combinations of active compound doses.

Pharmaceutical compositions which can be used orally include push-fit capsules made of gelatin as well as soft, sealed capsules made of gelatin and a plasticizer, such as glycerol or sorbitol. The push-fit capsules may contain the active ingredients in admixture with filler such as lactose, binders such as starches, lubricants such as talc or magnesium stearate and, optionally, stabilizers. In soft capsules, the active ingredients may be dissolved or suspended in suitable liquids, such as fatty oils, liquid paraffin, or liquid polyethylene glycols. In addition, stabilizers may be added. All formulations for oral administration should be in dosages suitable for the chosen route of administration.

For buccal administration, the compositions may take the form of tablets or lozenges formulated in conventional manner.

For administration by nasal inhalation, the active ingredients for use according to some embodiments of the invention are conveniently delivered in the form of an aerosol spray presentation from a pressurized pack or a nebulizer with the use of a suitable propellant, e.g., dichlorodifluoromethane, trichlorofluoromethane, dichloro-tetrafluoroethane or carbon dioxide. In the case of a pressurized aerosol, the dosage unit may be determined by providing a valve to deliver a metered amount. Capsules and cartridges of, e.g., gelatin for use in a dispenser may be formulated containing a powder mix of the active compound and a suitable powder base such as lactose or starch.

The pharmaceutical composition described herein may be formulated for parenteral administration, e.g., by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form, e.g., in ampoules or in multidose containers with optionally, an added preservative. The compositions may be suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents.

Pharmaceutical compositions for parenteral administration include aqueous solutions of the active preparation in water-soluble form. Additionally, suspensions of the active ingredients may be prepared as appropriate oily or water based injection suspensions. Suitable lipophilic solvents or vehicles include fatty oils such as sesame oil, or synthetic fatty acids esters such as ethyl oleate, triglycerides or liposomes. Aqueous injection suspensions may contain substances, which increase the viscosity of the suspension, such as sodium carboxymethyl cellulose, sorbitol or dextran.

Optionally, the suspension may also contain suitable stabilizers or agents which increase the solubility of the active ingredients to allow for the preparation of highly concentrated solutions.

The pharmaceutical composition of some embodiments of the invention may also be formulated in rectal compositions such as suppositories or retention enemas, using, e.g., conventional suppository bases such as cocoa butter or other glycerides.

In some embodiments, a pharmaceutical composition as described herein is prepared prior to administration to a patient. In some embodiments, a pharmaceutical composition as described herein comprises a fluorine- 18 radiolabeled compound as described herein, and is prepared 20-240 minutes, or 30 to 240 minutes, or 30 to 180 minutes, or 30 to 120 minutes, or 30 to 60 minutes, prior to administration to a patient.

In some embodiments, a pharmaceutical composition as described herein comprises a bromine-76 or bromine-77 radiolabeled compound as described herein, and can be prepared 1-48 hours, or 1-24 hours minutes, prior to administration to a patient, although shorter time periods are also contemplated.

In some embodiments, a pharmaceutical composition as described herein comprises iodine- 123, iodine- 124 or iodine- 131 radiolabeled compound as described herein, and can be prepared from 1 hour to several days, prior to administration to a patient, as described herein, although shorter time periods are also contemplated.

In some of any of the embodiments described herein, a radioimaging method as described herein is performed 0-120 minutes, or 0-60 minutes, or 0-40 minutes, or 0-20 minutes, after administration of the composition to a patient.

It is expected that during the life of a patent maturing from this application relevant OCTs, including human OCTs will be developed and the scope of the term "organic cation transporter" is intended to include all such new technologies a priori.

It is further expected that during the life of a patent maturing from this application many relevant therapies which efficacy correlates with OCTs will be uncovered and the scope of such therapies is intended to include all such new methodologies a priori.

It is further expected that during the life of a patent maturing from this application relevant radioactive atoms and respective nuclear imaging techniques will be developed and the scope of the terms "radioactive atom" and "radioimaging" is intended to include all such new technologies a priori.

The compounds described herein, including the radiolabeled compounds, include quaternary ammonium salts, and in some of any of the embodiments described herein, these salts are pharmaceutically acceptable salts.

The present embodiments encompass any enantiomers, diastereomers, prodrugs, solvates, hydrates and/or pharmaceutically acceptable salts of the compounds described herein.

As used herein, the term "enantiomer" refers to a stereoisomer of a compound that is superposable with respect to its counterpart only by a complete inversion/reflection (mirror image) of each other. Enantiomers are said to have "handedness" since they refer to each other like the right and left hand. Enantiomers have identical chemical and physical properties except when present in an environment which by itself has handedness, such as all living systems. In the context of the present embodiments, a compound may exhibit one or more chiral centers, each of which exhibiting an R- or an 5-configuration and any combination, and compounds according to some embodiments of the present invention, can have any their chiral centers exhibit an R- or an 5-configuration.

The term "diastereomers", as used herein, refers to stereoisomers that are not enantiomers to one another. Diastereomerism occurs when two or more stereoisomers of a compound have different configurations at one or more, but not all of the equivalent (related) stereocenters and are not mirror images of each other. When two diastereoisomers differ from each other at only one stereocenter they are epimers. Each stereo-center (chiral center) gives rise to two different configurations and thus to two different stereoisomers. In the context of the present invention, embodiments of the present invention encompass compounds with multiple chiral centers that occur in any combination of stereo-configuration, namely any diastereomer.

The term "prodrug" refers to an agent, which is converted into the active compound (the active parent drug) in vivo. Prodrugs are typically useful for facilitating the administration of the parent drug. They may, for instance, be bioavailable by oral administration whereas the parent drug is not. A prodrug may also have improved solubility as compared with the parent drug in pharmaceutical compositions. Prodrugs are also often used to achieve a sustained release of the active compound in vivo. An example, without limitation, of a prodrug would be a compound of the present invention, having one or more carboxylic acid moieties, which is administered as an ester (the "prodrug"). Such a prodrug is hydrolyzed in vivo, to thereby provide the free compound (the parent drug). The selected ester may affect both the solubility characteristics and the hydrolysis rate of the prodrug.

The term "solvate" refers to a complex of variable stoichiometry (e.g., di-, tri-, tetra-, penta-, hexa-, and so on), which is formed by a solute (the compound of the present invention) and a solvent, whereby the solvent does not interfere with the biological activity of the solute. Suitable solvents include, for example, ethanol, acetic acid and the like.

The term "hydrate" refers to a solvate, as defined hereinabove, where the solvent is water.

The terms "hydroxyl" or "hydroxy", as used herein, refer to an -OH group.

As used herein, the term "amine" describes a -NR'R" group where each of R' and R" is independently hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, heteroalicyclic, aryl, heteroaryl, alkaryl, alkheteroaryl, or acyl, as these terms are defined herein. Alternatively, one or both of R' and R" can be, for example, hydroxy, alkoxy, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, carbonyl, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine and hydrazine.

The term "amide" also describes a -NR.'- linking group (a biradical group, attached to two moieties), with R' as described herein.

As used herein, the term "alkyl" describes an aliphatic hydrocarbon including straight chain and branched chain groups. The alkyl may have 1 to 20 carbon atoms, or 1-10 carbon atoms, and may be branched or unbranched. Whenever a numerical range; e.g., "1-10", is stated herein, it implies that the group, in this case the alkyl group, may contain 1 carbon atom, 2 carbon atoms, 3 carbon atoms, etc., up to and including 10 carbon atoms. In some embodiments, the alkyl is a lower alkyl, including 1-6 or 1-4 carbon atoms.

An alkyl can be substituted or unsubstituted. When substituted, the substituent can be, for example, one or more of an alkyl (forming a branched alkyl), an alkenyl, an alkynyl, a cycloalkyl, an aryl, a heteroaryl, a heteroalicyclic, a halo, a trihaloalkyl, a hydroxy, an alkoxy and a hydroxyalkyl as these terms are defined hereinbelow. An alkyl substituted by aryl is also referred to herein as "alkaryl", an example of which is benzyl. The alkyl can be substituted by other substituents, as described hereinbelow.

The term "alkenyl" describes an unsaturated alkyl, as defined herein, having at least two carbon atoms and at least one carbon-carbon double bond, e.g., allyl, vinyl, 3-butenyl, 2-butenyl, 2-hexenyl and i-propenyl. The alkenyl may be substituted or unsubstituted by one or more substituents, as described hereinabove.

The term "alkynyl", as defined herein, is an unsaturated alkyl having at least two carbon atoms and at least one carbon-carbon triple bond. The alkynyl may be substituted or unsubstituted by one or more substituents, as described hereinabove.

The term "cycloalkyl" refers to an all-carbon monocyclic or fused ring (i.e., rings which share an adjacent pair of carbon atoms), branched or unbranched group containing 3 or more carbon atoms where one or more of the rings does not have a completely conjugated pi-electron system, and may further be substituted or unsubstituted. Exemplary cycloalkyl groups include, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or cyclododecyl. The cycloalkyl can be substituted or unsubstituted.

The term "aryl" describes an all-carbon monocyclic or fused-ring polycyclic (i.e., rings which share adjacent pairs of carbon atoms) groups having a completely conjugated pi-electron system. The aryl group may be unsubstituted or substituted by one or more substituents. An aryl substituted by alkyl is also referred to herein as "aralkyl", as example of which is toluyl.

The term "heteroaryl" describes a monocyclic or fused ring (i.e., rings which share an adjacent pair of atoms) group having in the ring(s) one or more atoms, such as, for example, nitrogen, oxygen and sulfur and, in addition, having a completely conjugated pi-electron system. Examples, without limitation, of heteroaryl groups include pyrrole, furane, thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidine, quinoline, isoquinoline and purine. Representative examples are thiadiazole, pyridine, pyrrole, oxazole, indole, purine and the like. The heteroaryl group may be unsubstituted or substituted by one or more substituents.

The term "heteroalicyclic", as used herein, describes a monocyclic or fused ring group having in the ring(s) one or more atoms such as nitrogen, oxygen and sulfur. The rings may also have one or more double bonds. However, the rings do not have a completely conjugated pi- electron system. Representative examples are morpholine, piperidine, piperazine, tetrahydrofurane, tetrahydropyrane and the like. The heteroalicyclic may be substituted or unsubstituted.

The term "halide", as used herein, refers to the anion of a halo atom, i.e. F ^" , CI ^" , Br ^" and Γ. The term "halo" or "halogen" refers to F, CI, Br and I atoms as substituents.

The term "alkoxide" refers to an R'-O ^" anion, wherein R' is as defined hereinabove.

The term "alkoxy" refers to an -OR' group, wherein R' is alkyl or cycloalkyl, as defined herein.

The term "aryloxy" refers to an -OR' group, wherein R' is aryl, as defined herein.

The term "heteroaryl oxy" refers to an -OR' group, wherein R' is heteroaryl, as defined herein.

The term "thioalkoxy" refers to an -SR' group, wherein R' is alkyl or cycloalkyl, as defined herein.

The term "thioaryloxy" refers to an -SR' group, wherein R' is aryl, as defined herein. The term "thioheteroaryloxy" refers to an -SR' group, wherein R' is heteroaryl, as defined herein.

The term "hydroxyalkyl," as used herein, refers to an alkyl group, as defined herein, substituted with one or more hydroxy group(s), e.g., hydroxymethyl, 2-hydroxyethyl and 4- hydroxypentyl.

The term "aminoalkyl," as used herein, refers to an alkyl group, as defined herein, substituted with one or more amino group(s). The term "alkoxyalkyl," as used herein, refers to an alkyl group substituted with one or more alkoxy group(s), e.g., methoxymethyl, 2-methoxyethyl, 4-ethoxybutyl, n-propoxyethyl and t-butylethyl.

The term "trihaloalkyl" refers to -CX ₃ , wherein X is halo, as defined herein. An exemplary haloalkyl is CF ₃ .

A "guanidino" or "guanidine" or "guanidinyl" or "guanidyl" group refers to an - RaNC(=NRd)-NRbRc group, where each of Ra, Rb, Rc and Rd can each be as defined herein for R' and R" .

A "guanyl" or "guanine" group refers to an RaRbNC(= Rd)- group, where Ra, Rb and Rd are each as defined herein for R' and R' ' .

Whenever an alkyl, cycloalkyl, aryl, alkaryl, heteroaryl, heteroalicyclic, acyl and any other moiety or group as described herein is substituted, it includes one or more substituents, each can independently be, but are not limited to, hydroxy, alkoxy, thiohydroxy, thioalkoxy, aryloxy, thioaryloxy, alkaryl, alkyl, alkenyl, alkynyl, sulfonate, sulfoxide, thiosulfate, sulfate, sulfite, thiosulfite, phosphonate, cyano, nitro, azo, sulfonamide, carbonyl, thiocarbonyl, C- carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, oxo, thiooxo, oxime, acyl, acyl halide, azo, azide, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidyl, hydrazine and hydrazide, as these terms are defined herein.

The term "cyano" describes a -C≡N group.

The term "nitro" describes an -N0 ₂ group.

The term "sulfate" describes a -0-S(=0) ₂ -OR' end group, as this term is defined hereinabove, or an -0-S(=0) ₂ -0- linking group, as these phrases are defined hereinabove, where R' is as defined hereinabove.

The term "thiosulfate" describes a -0-S(=S)(=0)-OR' end group or a -0-S(=S)(=0)- O- linking group, as these phrases are defined hereinabove, where R' is as defined hereinabove.

The term "sulfite" describes an -0-S(=0)-0-R' end group or a -0-S(=0)-0- group linking group, as these phrases are defined hereinabove, where R' is as defined hereinabove.

The term "thiosulfite" describes a -0-S(=S)-0-R' end group or an -0-S(=S)-0- group linking group, as these phrases are defined hereinabove, where R' is as defined hereinabove.

The term "sulfinate" describes a -S(=0)-OR' end group or an -S(=0)-0- group linking group, as these phrases are defined hereinabove, where R' is as defined hereinabove.

The term "sulfoxide" or "sulfinyl" describes a -S(=0)R' end group or an -S(=0)- linking group, as these phrases are defined hereinabove, where R' is as defined hereinabove. The term "sulfonate" or "sulfonyl" describes a -S(=0)2-R' end group or an -S(=0) ₂ - linking group, as these phrases are defined hereinabove, where R' is as defined herein.

The term "S-sulfonamide" describes a -S(=0) ₂ - R'R" end group or a -S(=0) ₂ - R'- linking group, as these phrases are defined hereinabove, with R' and R' ' as defined herein.

The term "N-sulfonamide" describes an R' S(=0) ₂ - R"- end group or a -S(=0) ₂ - R'- linking group, as these phrases are defined hereinabove, where R' and R" are as defined herein.

The term "carbonyl" or "carbonate" as used herein, describes a -C(=0)-R' end group or a -C(=0)- linking group, as these phrases are defined hereinabove, with R' as defined herein.

The term "thiocarbonyl " as used herein, describes a -C(=S)-R' end group or a -C(=S)- linking group, as these phrases are defined hereinabove, with R' as defined herein.

The term "oxo" as used herein, describes a (=0) group, wherein an oxygen atom is linked by a double bond to the atom (e.g., carbon atom) at the indicated position.

The term "thiooxo" as used herein, describes a (=S) group, wherein a sulfur atom is linked by a double bond to the atom (e.g., carbon atom) at the indicated position.

The term "oxime" describes a =N-OH end group or a =N-0- linking group, as these phrases are defined hereinabove.

The term "acyl halide" describes a -(C=0)R"" group wherein R"" is halo, as defined hereinabove.

The term "azo" or "diazo" describes an -N= R' end group or an -N=N- linking group, as these phrases are defined hereinabove, with R' as defined hereinabove.

The term "azide" describes an -N ₃ end group.

The term "carboxylate" as used herein encompasses C-carboxylate and O-carboxylate.

The term "C-carboxylate" describes a -C(=0)-OR' end group or a -C(=0)-0- linking group, as these phrases are defined hereinabove, where R' is as defined herein.

The term "O-carboxylate" describes a -OC(=0)R' end group or a -OC(=0)- linking group, as these phrases are defined hereinabove, where R' is as defined herein.

A carboxylate can be linear or cyclic. When cyclic, R' and the carbon atom are linked together to form a ring, in C-carboxylate, and this group is also referred to as lactone. Alternatively, R' and O are linked together to form a ring in O-carboxylate. Cyclic carboxylates can function as a linking group, for example, when an atom in the formed ring is linked to another group.

The term "thiocarboxylate" as used herein encompasses C-thiocarboxylate and O- thiocarboxylate. The term "C-thiocarboxylate" describes a -C(=S)-OR' end group or a -C(=S)-0- linking group, as these phrases are defined hereinabove, where R' is as defined herein.

The term "O-thiocarboxylate" describes a -OC(=S)R' end group or a -OC(=S)- linking group, as these phrases are defined hereinabove, where R' is as defined herein.

A thiocarboxylate can be linear or cyclic. When cyclic, R' and the carbon atom are linked together to form a ring, in C-thiocarboxylate, and this group is also referred to as thiolactone. Alternatively, R' and O are linked together to form a ring in O-thiocarboxylate. Cyclic thiocarboxylates can function as a linking group, for example, when an atom in the formed ring is linked to another group.

The term "carbamate" as used herein encompasses N-carbamate and O-carbamate.

The term "N-carbamate" describes an R"OC(=0)-NR'- end group or a -OC(=0)-NR'- linking group, as these phrases are defined hereinabove, with R' and R" as defined herein.

The term "O-carbamate" describes an -OC(=0)-NR'R" end group or an -OC(=0)-NR'- linking group, as these phrases are defined hereinabove, with R' and R" as defined herein.

A carbamate can be linear or cyclic. When cyclic, R' and the carbon atom are linked together to form a ring, in O-carbamate. Alternatively, R' and O are linked together to form a ring in N-carbamate. Cyclic carbamates can function as a linking group, for example, when an atom in the formed ring is linked to another group.

The term "carbamate" as used herein encompasses N-carbamate and O-carbamate.

The term "thiocarbamate" as used herein encompasses N-thiocarbamate and O- thiocarbamate.

The term "O-thiocarbamate" describes a -OC(=S)-NR'R" end group or a -OC(=S)-NR'- linking group, as these phrases are defined hereinabove, with R' and R" as defined herein.

The term "N-thiocarbamate" describes an R"OC(=S)NR'- end group or a -OC(=S)NR'- linking group, as these phrases are defined hereinabove, with R' and R" as defined herein.

Thiocarbamates can be linear or cyclic, as described herein for carbamates.

The term "dithiocarbamate" as used herein encompasses S-dithiocarbamate and N- dithioc arb amate .

The term "S-dithiocarbamate" describes a -SC(=S)-NR'R" end group or a -SC(=S)NR'- linking group, as these phrases are defined hereinabove, with R' and R" as defined herein.

The term "N-dithiocarbamate" describes an R"SC(=S)NR'- end group or a -SC(=S)NR'- linking group, as these phrases are defined hereinabove, with R' and R" as defined herein. The term "urea", which is also referred to herein as "ureido", describes a -NR'C(=0)- R"R" ' end group or a - R'C(=0)- R"- linking group, as these phrases are defined hereinabove, where R' and R" are as defined herein and R" is as defined herein for R and R".

The term "thiourea", which is also referred to herein as "thioureido", describes a -NR'- C(=S)- R"R'" end group or a -NR'-C(=S)-NR"- linking group, with R', R" and R' " as defined herein.

The term "amide" as used herein encompasses C-amide and N-amide.

The term "C-amide" describes a -C(=0)-NR'R" end group or a -C(=0)-NR'- linking group, as these phrases are defined hereinabove, where R' and R" are as defined herein.

The term "N-amide" describes a R'C(=0)-NR"- end group or a R'C(=0)-N- linking group, as these phrases are defined hereinabove, where R' and R" are as defined herein.

The term "hydrazine" describes a -NR'-NR"R" ' end group or a -NR'-NR"- linking group, as these phrases are defined hereinabove, with R', R", and R" as defined herein.

As used herein, the term "hydrazide" describes a -C(=0)-NR'-NR"R" end group or a - C(=0)-NR'-NR"- linking group, as these phrases are defined hereinabove, where R', R" and R'" are as defined herein.

As used herein, the term "thiohydrazide" describes a -C(=S)-NR'-NR"R" end group or a -C(=S) -NR'-NR"- linking group, as these phrases are defined hereinabove, where R', R" and R'" are as defined herein.

As used herein the term "about" refers to ± 10 % or ± 5 %.

The terms "comprises", "comprising", "includes", "including", "having" and their conjugates mean "including but not limited to".

The term "consisting of means "including and limited to".

The term "consisting essentially of" means that the composition, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases "ranging/ranges between" a first indicate number and a second indicate number and "ranging/ranges from" a first indicate number "to" a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

As used herein the term "method" refers to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, pharmacological, biological, biochemical and medical arts.

As used herein, the term "treating" includes abrogating, substantially inhibiting, slowing or reversing the progression of a condition, substantially ameliorating clinical or aesthetical symptoms of a condition or substantially preventing the appearance of clinical or aesthetical symptoms of a condition.

As used herein throughout, the term "patient", which is used interchangeably with

"subject" describes animals, including mammals, preferably human beings, at any age, which suffer, or are at risk to suffer, or are suspected as suffering, from a pathology. Preferably, this term encompasses individuals who are at risk to develop the pathology.

The term "tissue" refers to part of an organism consisting of cells designed to perform a function or functions. Examples include, but are not limited to, brain tissue, retina, skin tissue, hepatic tissue, pancreatic tissue, bone, cartilage, connective tissue, blood tissue, muscle tissue, cardiac tissue, vascular tissue, renal tissue, pulmonary tissue, gonadal tissue, hematopoietic tissue, and tumor tissue, including benign and malignant tumor tissues.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below find experimental support in the following examples. EXAMPLES

Reference is now made to the following examples, which together with the above descriptions illustrate some embodiments of the invention in a non limiting fashion.

EXAMPLE 1

Chemical Synthesis ofFEtQ

Materials and Experimental Methods:

Radioactive halides are generated as follows:

Radioactive fluoride- 18 ion is produced via the 180(p,n) 18 F nuclear reaction using a IB A cyclotron equipped with a fluorine- 18 target. The [ 18 F]fluoride is delivered from the cyclotron

(in a 3 ml bolus of [ 180]H ₂ 0) and trapped on a anion exchange cartridge to remove [ 1 ^l 8 ^o 0]H ₂ 0.

[ 18 F]Fluoride is then eluted into the reaction vessel using aqueous potassium carbonate (4 mg in 0.5 mL of water). A solution of kryptofix-2.2.2 (15 mg in 1 mL of acetonitrile) is then added to the reaction vessel and the [ 18 F] fluoride is dried by evaporating the water=acetonitrile azeotrope under heating and reduced pressure followed by cooling to 60 °C.

Radioactive iodine- 123, radioactive iodine- 124 and radioactive iodine- 131 are obtainable from commercial vendors.

Radioactive bromine-76 and radioactive bromine-77 are obtainable from commercial vendors.

Radiochemical purity is determined using an analytical HPLC Varian ProStar model 230 (Palo Alto, CA, USA) equipped with UV Detector, JASCO UV-2075 plus (Tokyo, Japan) and PMT/scintillator detector Bioscan flow count).

Preparative HPLC is performed using a Varian 9012Q HPLC system employed with an Varian 9050 UV-VIS detector and C18 HPLC column (Bischoff Nucleosil CI 8, 7 μιη, 250 mm x 16 mm, Marchery-Nagel GmbH, Duren, Germany).

Semi-preparative HPLC is performed using Varian 9012Q HPLC system employed with a Varian 9050 UV-VIS detector and C18 column (Luna, Phenomenex, Torrance, CA, USA).

Analytical HPLC is performed using analytical HPLC Varian ProStar model 230 (Palo Alto, CA, USA) equipped with UV Detector, JASCO UV-2075 plus (Tokyo, Japan). 1H-NMR and ¹⁹ F-NMR spectra are obtained using Varian VXR-300 (300 MHz spectrometer equipped with a 5 mm probe).

HRMS was performed using an ESI LTQ Orbitrap XL spectrophotometer equipped with FTMS Analyzer (Resolution: 100000). The data collected using Xcalibur 2.1 program.

Preparation of fluoroethyl quinolinium (FEtQ):

l-(2-fluoroethyl)quinolin-l-ium, which is also referred to herein as fluoroethyl quinolinium or is abbreviated as FEtQ, was prepared in a two-step synthesis, starting with 2- fluoroethanol, as depicted in Scheme 1 below.

Scheme 1

2-fluoroethanol

fluoroethyl quinolinium

Synthesis of fluoroethyltosylate (step 1):

2-Fluoroethanol (120 mg, 1.87 mmol, Sigma Aldrich) was dissolved in dry dichloromethane (2 mL) and added to a solution of /?-toluenesulfonyl chloride (540 mg, 2.83 mmol, Sigma Aldrich), 252mg of trimethylamine (4.26 mmol, Sigma Aldrich) and 26 mg (212.8 μιηοΐ, Sigma Aldrich) DMAP dissolved in 2 mL dry dichloromethane. The reaction was stirred for 2 hours at room temperature and was thereafter concentrated and purified on a silica gel column using hexane:ethyl acetate (9:1) as eluent to yield the fluoroethyl tosylate.

1H-NMR (300 MHz, CDC1 ₃ ): δ = 2.45 (s, 3H), 4.22 (t, 7=4.2 Hz, 1H), 4.31 (t, 7=4.2 Hz, 1H), 4.48 (t, 7=4.2 Hz, 1H), 4.64 (t, 7=4.2 Hz, 1H), 7.35 (d, 7=8.4 Hz, 2H), 7.80 (d, 7=8.4 Hz, 2H).

¹⁹ F-NMR (300 MHz, CDC1 ₃ ): δ = -224.65 (h, IF). Synthesis of non-labeled FEtQ (cold standard) (step 2):

Quinoline (160 μί, 1.35 mmol, Sigma Aldrich, Rehovot, Israel) was added to a solution of 1.7 grams (7.8 mmol) fluoroethyltosyalte in 6 mL dry DMF (Sigma Aldrich), and the reaction was refluxed for 72 hours under a nitrogen atmosphere. The solution was then cooled and concentrated in vacuum to yield a light brown oil. The crude product was purified using a semi- preparative HPLC system equipped with a semi-preparative column (Luna C I 8, 100 A, 5 μιη, 250x10 mm) using (A) H ₂ 0: (B) acetonitrile gradient (from 100% to 60% (A) over 15 minutes at a constant gradient and flow, 4 mL/minute).

1H-NMR (300 MHz, Deuterium Oxide): δ = 2.17 (s, 3H), 4.81 (t, = 4.6 Hz, 1H), 4.97 (dd, J _\ = 4.0 Hz, ₂ = 5.1 Hz, 1H), 5.19 (t, = 4.6 Hz, 1H), 5.27 (t, = 4.6 Hz, 1H), 7.18 - 7.08 (m, 2H), 7.46 (d, = 8.2 Hz, 2H), 7.93 - 7.78 (m, 2H), 8.07 (ddd, J _l = 1.5 Hz, J ₂ = 7.1 Hz, / ₃ = 8.9 Hz, 1H), 9.03 - 8.93 (m, 1H), 8.28 - 8.15 (m, 2H), δ 9.07 (d, = 5.9 Hz, 1H).

¹⁹ F-NMR (300 MHz, DMSO-d ₆ ): δ = -221.14 (m, IF). HR-MS: calculated: 176.06700; Found: 176.06662. EXAMPLE 2

Radiosynthesis of Fluorine-18 labeled FEtQ

Fluorine- 18 labeled FEtQ was prepared in a one-step radiosynthesis using 2-N'- ethylquinolinium triflate. 2-N'-ethylquinolinium triflate, was prepared by a two-step reaction, as depicted in Scheme 2 below. The first step involved synthesis of the reagent ethylene glycol bistriflate, which was further reacted with quinoline in the second step, to yield 2-N'- ethylquinolinium triflate. The latter was analyzed by 1H, ¹⁹ F and ¹³ C NMR, high resolution mass spectrometry (HR-MS) and by HPLC.

Scheme 2

O

ethylene glycol bistriflate

ethylene glycol bistriflate

2-N'-ethylquinolinium triflate

Synthesis of ethylene glycol bistriflate (step 1):

A solution of 1.06 mL (6.3 mmol) triflic anhydride (trifluoromethanesulfonic anhydride, Sigma Aldrich, Rehovot, Israel) in 3 mL of dry dichloromethane (Acros Organics, Geel, Belgium) was stirred in an ice bath under a nitrogen atmosphere and light exclusion. A solution of 180 μΐ _^ (3.2 mmol) ethylene glycol (Sigma Aldrich) and 521 μL· (6.4 mmol) dry pyridine (Sigma Aldrich), dissolved in 3.5 mL of dry dichloromethane was then added in portions over 10 minutes. The obtained solution was left stirring for additional 15 minutes. The solution was thereafter diluted with 20 mL of cold dichloromethane and washed twice with cold HPLC water. The organic layer was dried using magnesium sulfate, filtered and evaporated at 30 °C for 30 minutes to yield the product as a clear and light red oil (0.85 gram, 80.7 % yield). This reagent was stored at -16 °C under a nitrogen atmosphere for several weeks.

1H-NMR (300 MHz, CDC1 ₃ ): δ = 4.52 (s, 4H).

¹⁹ F-NMR (300 MHz, CDC1 ₃ ): δ = -74.3 (s, 6F).

18

Synthesis of 2-N ' -ethylquinolinium triflate (precursor for [ F]FEtQ):

A solution of 100 μΐ _^ (0.55 mmol) ethylene glycol bistriflate in 4 mL of dry dichloromethane was cooled to -50 °C under a nitrogen atmosphere and light exclusion. A solution of 31 μΐ _^ quinoline (0.24 mmol, Sigma Aldrich) in 4 mL dry dichloromethane was then added over 10 minutes. The solution was allowed to reach room temperature and was left stirring for additional 48 hours. The reaction was thereafter cooled in an ice bath for 20 minutes and cold ether was added for additional 20 minutes. The mixture was filtered through a sintered glass filter equipped with filter paper under reduced pressure, and the precipitation was further washed with 100 mL of cold ether. The collected white precipitant was then dried using dry toluene evaporation to yield the product (84.6 mg, 80.4 % yield, n=3). This reagent was stored at -16 °C under nitrogen atmosphere for several weeks.

1H-NMR (300 MHz, DMSO-d ₆ ): δ = 4.77 (t, 7=4.7 Hz, 2H), δ 5.41 (t, 7=4.7, 2H), δ 8.0 - 8.36 (m, 4H), δ 8.43 - 8.65 (m, 3H), δ 9.30 - 9.42 (m, 2H).

¹⁹ F-NMR (300 MHz, DMSO-d ₆ ): δ = -77.77 (s, 3F).

Radiolabeling of [ ¹⁸ F]FEtQ:

[ 18 F]FEtQ was synthesized by a fully automated, one-step reaction, as depicted in

Scheme 3 below. 18 F ^" anion was reacted with the 2-N'-ethylquinolinium triflate precursor, and was subsequently purified on a semi-preparative HPLC system.

Scheme 3

2-N'-ethylquinolinum triflate [ F]fluoroethylquinoline

([ ¹⁸ F]FEtQ

[ F]FEtQ was synthesized using an automated GE TRAER Lab module. Reagent vials were loaded as follows: Vial 1: potassium carbonate (0.5 mL of a 8 mg/mL solution, Sigma Aldrich), Vial 2: kryptofix-2.2.2 (15 mg dissolved in 1 mL MeCN, Merck, Darmstadt, Germany), Vial 3: ethyltriflatequinoline 17-20 mg dissolved in 1.4 mL dry dichloromethane, Vial 4: 1.9 mL of HPLC eluent (97:3 of acetate buffer 0.1 M, pH 5.2: EtOH), Collection vial: 0.9% sodium chloride solution for injection (5 mL).

The radioactive fluoride- 18 anion was produced via the 18 Ο(ρ,η) 18 F nuclear reaction using an IBA cyclotron equipped with a target for generating [ 18 F]fluoride. The latter was delivered from the cyclotron (in a 3 mL bolus of [ 180]H ₂ 0), and trapped on a solid phase extraction anion exchange cartridge (CHROMAFIX PS-HCO ₃ , Marcherey Nagle, Diiren,

Germany). [ 18 F]fluoride was then eluted into the reaction vessel using aqueous potassium carbonate (4 mg in 0.5 mL of water). A solution of kryptofix-2.2.2 (ABX, Radeberg, Germany,

15 mg in 1 mL of acetonitrile) was then added onto the reaction vessel and the [ 18 F]fluoride was dried by evaporating the water- acetonitrile azeotrope under heat and reduced pressure, followed by cooling to 50 °C.

At the end of the evaporation process, 17-20 mg of the ethyltriflate quinoline dissolved in 1.4 mL of dry dichloromethane was added to the reactor, and the fluorination step was performed in a sealed reactor at 95 °C for 5 minutes under an inert atmosphere. Thereafter, the reaction mixture was cooled, and 1.9 mL of 97 % acetate buffer 0.1 M, pH 5.2 and 3 % of ethanol was added to the reactor. The obtained mixture was filtered through a polypropylene 0.45 μιη filter (Whatman, GE Healthcare) and further purified on a semi-preparative HPLC system using RP-C18 column (Luna, Phenomenex) using 97 % acetate buffer pH 5.2, 0.1 M and 3 % of ethanol in a constant ratio (isocratic) eluent at a flow of 4 mL/ min. [ 18 F]FEtQ retention time was 18.5 minutes and a peak of 30-45 sec (2-3 mL) was transferred to the collection vial containing 5 mL of saline.

Chemical and radiochemical purities were determined using an analytical HPLC and a UV detector at a wavelength of λ=316 nm, as described herein under the quality control analysis section.

Overall, following a total synthesis time of 44 minutes, 27.24 + 11.5 GBq of [ ¹⁸ F]FEtQ were obtained (n = 4) with an average radiochemical yield of 25 %, after purification, decay corrected (DC) to the end of bombardment (EOB). Radiochemical purity was routinely > 95 %, and the specific activity was higher than 79.6 ± 8 GBq/μπιοΙ, DC to EOB.

18

Quality control analysis of [ F]FEtQ:

Quality control analysis was performed using an analytical HPLC, equipped with a variable wavelength UV detector at λ=316 nm and a radioactivity detector with Nal crystals. A Phenomenex Luna CI 8(2) column (5 μπι, 100A, 4.6 mm x 250 mm) was used, with a gradient mobile phase system of (A) 0.05% TFA in water: (C) 0.05 % TFA in acetonitrile at a constant flow rate of 1.2 mL/min (gradient from 100 % to 65 % (A) in 22 minutes). Identification of

[ 18 F]FEtQ was confirmed by a co-injection of the non-labeled fluoroethyl quinolinium standard, having retention times of 20.4 minutes and 20.9 minutes, respectively.

Residual kryptofix-2.2.2 (K222) levels in the final product were analyzed using the established spot test. Strips of plastic coated with silica gel, TLC plates saturated with iodoplatinate reagent were spotted with standard solutions containing 0, 0.025, 0.05 and 0.01 mg/mL of kryptofix 2.2.2, dissolved in 97 % of 0.1 M acetate buffer (pH 5.2) and 3 % of EtOH. The absence of kryptofix 2.2.2 in the final product was confirmed or appeared lower than 0.025 mg/mL. Solvent residues were analyzed using a 1 injection of the final product to a GC instrument, and compared to a standard solution containing 0.04 % acetonitrile and 0.5 % acetone. Standard area counts and corresponding retention times were 23,172 area counts at 6.4 minutes for acetonitrile, and 275,328 area counts at 8.9 minutes, for acetone.

The solution was inspected for its clearness and transparency and was colorless or in some cases light yellow.

The solution's pH was confirmed as 5-5.2 by pH indicator strips (pH 4-7, Merck, Darmstadt, Germany).

EXAMPLE 3

Uptake by OCT-transfected cells

In vitro studies using stably transfected human embryonal kidney (HEK)-293 cells:

HEK293 cells were stably transfected with the cDNAs of hOCTl, hOCT2, hOCT3 or the empty (pcDNA3) vector (EV) and were obtained from Prof. Griindemann, Department of Pharmacology, University Hospital Cologne, Germany [Grundemann, D., et al., Biol Chem, 1997; 272(16): 10408-13].

The cells were cultured at 37 °C in an atmosphere of 5 % C0 ₂ and 95 % relative humidity, in DMEM (lg/L glucose) with 10 % FBS and penicillin- streptomycin (lOOU/0.1 mg/ mL). Expression of the hOCTl -2 or -3 was verified by RT-PCR.

The time-course of [ 18 F]FEtQ uptake into HEK-293 cells expressing either of the OCTs or the EV was investigated by incubating the different cells lines in Krebs-Ringer-Henseleit buffer (pH 7.4) with the radiopharmaceutical for increasing periods of time (0-30 minutes). Subsequently, the solutions were aspirated, the cells were washed twice with ice-cold DPBS and solubilized with 1 % Triton X-100. The intracellular accumulation of radioactivity was determined using a gamma counter (2480 Wizard PerkinElmer, Germany). The total radioactivity taken up by the cells was normalized by the overall added radioactivity and by protein concentrations, as determined using a BCA Protein assay kit.

The results are presented in FIGs. 1A-C and reveal rapid uptake of [ 18 F]FEtQ into OCT- expressing cells, which reached a plateau after 5-10 minutes for all OCTs. The accumulation of

[ 18 F]FEtQ in these cells was 15-20-fold higher than in cells expressing the EV, indicating an OCT-mediated cellular accumulation. 18

In vitro inhibition of [ FJFEtQ uptake in stably transfected HEK293 cells overexpressing hOCT3:

Corticosterone is an inhibitor of the hOCTl-3, with about 100-fold higher potency for hOCT3 compared to hOCTl and hOCT2 [Koepsell et al. Pharm Res. Jul 2007 ;24(7): 1227- 1251]. In vitro uptake inhibition experiments were therefore conducted in the presence of corticosterone, to test hOCT3 uptake inhibition.

HEK293 cells stably expressing the hOCT3 or EV were incubated in Krebs-Ringer- Henseleit buffer (pH 7.4) and pretreated for 30 minutes with various concentrations of corticosterone (0.05, 0.5 and 5.0 μΜ), before a 15 minutes co-incubation with [ 18 F]FEtQ.

Intracellular accumulation of radioactivity was measured and normalized as described above, and the obtained data is presented in FIG. 2. As can be seen, uptake in untreated hOCT3 expressing cells was 12-fold higher compared to the EV control, and was significantly inhibited by corticosterone. The levels of inhibition are in good agreement with the reported corticosterone hOCT3 IC50 (0.3 μΜ; Koepsell et al. 2007 {supra)).

EXAMPLE 4

In vivo PET-CT and biodistribution studies

In vivo PET-CT and biodistribution studies following i.v. injection of [ 18 FJFEtQ into male SD rats:

To investigate the distribution kinetics of [ 18 F]FEtQ, male Sprague Dawley rats (296 + 9 grams, n = 7) were anesthetized with isoflurane (2.5 % in 0 ₂ ), and following a CT scan, injected with [ 18 F]FEtQ (17.7 + 1 MBq) via the lateral tail vein. PET acquisitions were started at the time of [ 18 F]FEtQ injection, and lasted for 45 minutes. At the end of each acquisition, the rat was sacrificed by an i.p injection of pentobarbitone sodium (CTS chemical industries Ltd., Kiryat Malachi, Israel), tissues and organs of interest were excised and weighed, and their radioactivity content was measured using a gamma counter. In addition, urine samples were collected and analyzed by HPLC for the presence of radioactive metabolites.

The obtained time-activity curves (TACs) are presented in FIGs. 3A-B and illustrate rapid radioactivity uptake in the left ventricle (LV) and the liver, followed by pronounced washout from both organs (FIG. 3A). Consequently, at 45 minutes after injection, radioactivity levels in the LV and the liver were only approximately 40 % of those measured at the peak of accumulation. A pronounced renal clearance was also observed (FIG. 3B).

FIGs. 4A-D show that [ 18 F]FEtQ yielded good quality images, with clear visualization of the LV and good contrast between the heart and its surrounding tissues. The distribution of radioactivity at 45 minutes after injection of [ 18 F]FEtQ was also studied by sacrificing each rat following its PET acquisition, harvesting organs and tissues of interest and measuring their radioactivity concentration.

Table 1 below presents the comparative SUVs calculated from these biodistribution studies and PET images at 45 minutes after injection of [ 18 F]FEtQ. Results are presented as mean + SD (n = 7, except for organs marked with an asterisk, wherein n = 3). ND = not determined. As can be seen, the biodistribution results are in good agreement with those obtained from the analysis of the PET images.

Table 1

As expected from a cationic quaternary salt, the major route of elimination was via renal clearance (see also FIG. 3B). Except for the urinary bladder, the highest radioactivity levels were measured in the heart, followed by the kidneys and the liver.

The presence of radioactive metabolites in the urine was analyzed by injecting 100 μΐ _^ of urine samples into an analytical HPLC, using the same gradient as aforementioned for [ 18 F]FEtQ QC. The results of the HPLC analysis of urine samples at 45 minutes, showing percentages of intact [ 18 F]FEtQ following injection are presented in Table 2 and indicate that at 45 minutes post 18

i.v. injection of [ F]FEtQ, most of the radioactivity present in the urine could be attributed to the intact compound, which comprised 77 + 10 % (n=7) of the total activity in the urine.

Table 2

In vivo PET-CT following injection of [ FJFEtQ into corticosterone- or vehicle- treated male SD rats:

The effect of corticosterone treatment was also tested in vivo. To test whether

18

corticosterone inhibits the LV accumulation of [ F]FEtQ, rats (n = 3) were administered with

18

corticosterone i.v. (3.3 mg/ kg) or vehicle 5 minutes prior to the i.v. injection of [ F]FEtQ (16.5 + 2 MBq). In addition, blood samples were drawn approximately 3 minutes after corticosterone or vehicle injection, and analyzed for corticosterone levels in serum.

FIGs. 5A-C present time-activity curves of the LV (FIG. 5A), liver (FIG. 5B) and

18

kidneys (FIG. 5C) obtained following i.v. injection of [ F]FEtQ into corticosterone- or vehicle- treated male SD rats (n = 3).

18

As demonstrated in FIG. 5A, [ F]FEtQ uptake in the LV of corticosterone-treated rats was significantly reduced compared to that of vehicle-treated animals (SUV 5.2 vs. 3.1 at 5 minutes after injection, respectively), suggesting that the OCT(3) -mediated cardiac uptake of

18

[ F]FEtQ could be inhibited by corticosterone.

Serum-corticosterone levels in blood samples taken from animals at 3 minutes after corticosterone injection were 6.33 + 1.66 μΜ (mean + SEM) (compared to 0.55 + 0.16 μΜ (mean + SEM) in vehicle-treated rats). These levels are in good agreement with the reported IC ₅₀ values of corticosterone for OCT2 and 3 (4-5 μΜ; Koepsell et al. 2007 (supra)). In vivo PET/CT of a non-human primate:

To investigate the distribution of [ 18 F]FEtQ in a non-human primate (NHP), the compound (94.35 MBq) was injected into an anesthetized female macaque monkey, weighing 4.7 Kg. The PET acquisition was composed of a 15-minutes dynamic scan, focused over the thorax, followed by three whole-body scans of 9 minutes each. The obtained images are presented in FIG. 6 and show that the major routes of elimination were renal and hepatobiliary, resulting in an intense radioactive signal in both the intestines and the urinary bladder.

EXAMPLE 5

In vivo PET-CT in OCT expressing tumor-bearing mice

Human OCT2 expressing tumor-bearing mice were established by subcutaneous injection of hOCT2 overexpressing HEK293 cells, into athymic nude mice. After tumor development, mice were anesthetized with isoflurane (1.5-2.5 % in 0 ₂ ) and subjected to a CT attenuation- correction scan. Subsequent 1-hour dynamic PET acquisitions were started at the time of i.v.

[ 18 F]FEtQ (7.5 + 0.2 MBq) injection into mice pre-treated without (= vehicle) or with the OCT inhibitor Decynium-22 (D-22; 0.38 mg/ kg).

Representative PET/CT images and time activity curves (TACs) are shown in FIGs. 7 A-

E. Uptake of [ 18 F]FEtQ was observed in the hOCT2 expressing tumors of vehicle treated mice (FIGs. 7A and 7C) and inhibited in D-22 treated mice (FIGs. 7B and 7D). The TACs (FIG. 7E) reveal a rapid uptake of radioactivity into the tumor followed by a slow washout over time. The pre-injection of D-22 significantly reduced (p<0.001) the uptake of the [ 18 F]FEtQ into the tumor, indicating specific hOCT2 mediated uptake.

In additional experiments, 1-hour dynamic PET acquisitions of human OCT2 expressing tumor-bearing mice were performed, and started at the time of i.v. [ 18 F]FEtQ (7.3 + 0.5 MBq) injection into mice pre-treated without (= vehicle; n=7) or with (n=5) the OCT inhibitor Decynium-22 (D-22; 0.076 + 0.003 mg/kg). The obtained TACs are presented in FIG. 8, and further demonstrate a rapid uptake of the [ 18 F]FEtQ into the tumor, which is reduced in the presence of pre-injected D-22, thus further supporting a specific hOCT2 mediated uptake.

Altogether, these data indicate that [ 18 F]FEtQ is a substrate of the OCTs, suggesting that PET radioimaging using [ 18 F]FEtQ enables a non-invasive screening for cancer patients whose tumors express OCTl-3, and thereby provides systemic information on tumor responsiveness to treatment with specific platinum compounds. EXAMPLE 6

Affinity studies

The affinity (Km) of [ 18 F]FEtQ to human OCT 1-3 is determined according to the following study protocol.

Affinity tests for [ 18 F]FEtQ experiments are performed using HEK293 cells expressing human OCT 1/2/3 or empty vector.

A stock solution of 0.1 mg/mL poly-L-ornithine, made of 10 mg of Poly-L-ornithine hydrobromide (Sigma P3655) in 100 mL of 150 mM boric acid-NaOH pH 8.4 is prepared by dissolving 0.927 grams of boric acid (Sigma: 339067-100G; MW=61.83g/mol) in 80 mL water; adjusting the pH to 8.4 with NaOH, and thereafter dissolving 10 mg of poly-L-ornithine in the buffer and adding up to 100 mL with water (pH remains at 8.4). The solution is sterilized by filtration or autoclaving. The solution is stable for 2-4 months in a refrigerator.

Wells are coated with Poly-L-ornithine (0.6 mL solution as described hereinabove was placed in each well, wells were incubated for at least 20 minutes at room temperature on an orbital shaker, the solution was thereafter aspirated and the wells were washed with 1.0 mL medium without FCS, which was thereafter aspirated). Prior to cells seeding, 2 mL growth medium is added to each well.

The tested HEK293 cells are suspended in the growth medium and their concentration is determined using a haemocytometer.

In eight 6- wells plates, 250,000 cells/ 1 mL/well (total volume per well is 2+1= 3 mL) are placed and distributed evenly, and are grown for 72 hours, until a confluent monolayer (70-95 %) is formed.

The medium is then replaced by a pre -heated (20 °C) transfer buffer (KHR solution), and the wells are incubated for 20 minutes at room temperature.

Krebs-Pvinger-Henseleit (KRH) solution (Transfer buffer; TB) is prepared with the following final concentrations: 5.6 mM (+) - glucose; 125 mM NaCl; 4.8 mM KC1; 1.2 mM KH ₂ P0 ₄ ; 1.2 mM CaCl ₂ ; 1.2 mM MgS0 ₄ ; 25 mM HEPES pH 7.4.

Stock solutions of [ 18 F]FEtQ in pre-incubated 20 °C TB as described herein are prepared using the original [ ¹⁸ F]FEtQ stock, and each includes 600 μθ [ ¹⁸ F]FEtQ in 15 mL TB (=10 μθ

[ 18 F]FEtQ in 0.250 mL/well). The activity in each stock solution is measured following preparation.

[ 18 F]FEtQ is added to all plates (0.250 mL/well) using 12 mL Combitips and the wells are incubated for various time periods at room temperature. At a relevant time point, the medium is rapidly aspirated from the wells, wells are washed twice with ice-cold PBS (4 mL/well), the PBS is aspirated, and 0.5 mL 1 % triton is added. The cells in each well are thereafter scraped, transferred to marked Eppendorf tubes and triturated to ensure complete lysis. 300 μΐ _^ of each cell lysate is thereafter transferred into a marked tube/vial for gamma counter readings.

The remaining lysate is kept at 4 °C overnight or at -20 °C for longer periods of time, for protein estimations after the radioactivity has decayed, using the Novagen BCA protein Assay Kit.

[ 18 F]FEtQ calibration curve is prepared by inserting 0.3 mL of PBS in each tube, adding approximately 24 μΟ/0.6 mL (directly from the stock solution) into a marked tube, and transferring 0.3 mL in 15 serial dilutions. The samples are then placed in the gamma counter and count twice.

Measurements of the Total Activity in the wells is performed by directly transfering 20 μL· (into 0.3 mL PBS) from a stock solution into the respective gamma counter tubes. Measurements are performed in triplicates.

EXAMPLE 7

Carbon-11 radiolabeled quinolinium salt

Synthesis of a non-radiolabeled standard:

Synthesis of N-methylquinolinium iodide (cold standard):

In a 10 mL round bottom flask equipped with a magnetic stirrer, 0.5 mL of quinoline and 3.5 mL (6 mol equivalents) of methyl iodide (neat, Sigma Aldrich) were mixed in a closed rubber septum under a nitrogen atmosphere, and the reaction mixture was heated at 40 °C overnight. The resulting brown solid was stirred with 10 mL of DCM/diethyl ether (1:3) for 1 hour and subsequently filtered. The resulting yellow solid was stirred with a 10 mL of hexane/DCM (6:4) mixture for an additional 1 hour. The resulting suspension was filtered to yield the pure product (80 %). The N-methylquinolinium iodide was analyzed by MS, ¹ H-NMR, HPLC and TLC.

1H-NMR (300 MHz, CDC1 ₃ ): δ = 10.21 (d, = 5.7 Hz, 1H), 8.99 (d, = 8.4 Hz, 1H), 8.39 - 8.24 (m, 2H), 8.16 (dd, = 8.4 Hz, J ₂ = 5.7 Hz, 1H), 8.05 (t, 1H), 4.95 (s, 3H).

ESI-MS: Mass (obtained) = 144.08, Mass (calculated) = 144.08.

Radiosynthesis:

[ ⁿ C]-Methyl quinolinium ([ ^u C]MeQ) was prepared in a one-step radiosynthesis as depicted in Scheme 4 below.

Radiosynthesis was carried out on an automated module (GE, Munster Germany). C- carbon dioxide was produced by the ¹⁴ N(p,a) ^u C nuclear reaction on nitrogen containing 0.5 % oxygen, using an 18/9 IB A cyclotron. At EOB, the target gas was delivered and trapped by a cryogenic trap in the [ ^u C]CH ₃ l module.

Carbon- 11 Mel was prepared as follows: [ ^u C]C0 ₂ (44 GBq, 1,000 mCi) was trapped at - 160 °C. The temperature of the cooling trap was increased to -20 °C, and the activity was transferred by a stream of argon (40 mL/minute) into the first reactor containing 300 μΐ _^ of 0.25 N LiAlH ₄ in THF at -50 °C. After 90 seconds, the solvent was removed under reduced pressure. In this manner, approximately 66 % of the activity was recovered. The reactor temperature was increased to 160 °C, HI (Hydroiodic acid, 57 %) was added and the obtained [ ⁿ C]MeI was distilled (argon flow of 15 mL/minute) through a NaOH column to the second reactor, containing quinoline 32.8 mg (0.23 mmol) dissolved in 400 μΐ _^ of acetonitrile at -20 °C. The reactor was sealed and heated to 80 °C for seven minutes and then the solvent was removed under argon flow, at 75 °C. The mixture was cooled to 40 °C, followed by the addition of 2 mL of ethanol/water (1: 1), and the crude product was transferred into an SPE flask containing 5 mL of water. Subsequently, the solution was loaded onto sep-pak accell plus CM light cartridge (Waters, Milford, Ma, USA, pre-activated with 20 mL HPLC water). The cartridge was washed with 5 mL of water, and the final product was eluted using 5 mL of sterile isotonic saline (0.9 % NaCl solution, B. Braun, Melsungen, Germany). The final solution was sterile filtered and was further used as is. Identification of the product was determined by the analytical HPLC system. Overall, following a total radiosynthesis and purification time of 30 minutes, 2.7 + 0.7GBq of [ ⁿ C]-N-methylquinolinium iodide were obtained (n=3) with a 35.7 + 3% radiochemical yield, decay corrected (DC) to the SOS. Radiochemical purity was routinely greater than 95 %. In vivo PET-CT and biodistribution in rats:

MicroPET/CT following i.v. injection of [ ⁿ C]Methyl quinolinium into rats:

To investigate the distribution kinetics of [ ^u C]MeQ, male Sprague Dawley rats were anesthetized, and following a CT scan, injected with [ ⁿ C]MeQ (15.9 + 0.3 MBq, n=3) via the lateral tail vein. PET acquisitions were started at the time of injection, and lasted for 25 minutes.

The obtained time-activity curves (TACs) are presented in FIG. 9A and illustrate rapid radioactivity uptake in the left ventricle (LV) and the liver, followed by pronounced washout from the liver. FIG. 9B show that [ ^u C]MeQ yielded good quality images, with clear visualization of the LV and good contrast between the heart and its surrounding tissues.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting.