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[0001] This application is a continuation-in-part of U.S. application Ser. No. 10/379,149, filed on Mar. 4, 2003, which claims the benefit of U.S. Provisional Application No. 60/361,759, filed Mar. 4, 2002. The entire teachings of these applications are incorporated herein by reference.
[0003] The present invention describes methods of treating cancers, e.g. mesothelioma. The present invention provides methods of selectively inducing terminal differentiation, cell growth arrest and/or apoptosis of neoplastic cells, and/or inhibiting histone deacetylases (HDAC) administration of pharmaceutical compositions comprising HDAC inhibitors. The oral formulations of the pharmaceutical compositions have favorable pharmacokinetic profiles such as high bioavailability and surprisingly give rise to high blood levels of the active compounds over an extended period of time.
[0004] Throughout this application various publications are referenced by arabic numerals within parentheses. Full citations for these publications may be found at the end of the specification immediately preceding the claims. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.
[0005] Cancer is a disorder in which a population of cells has become, in varying degrees, unresponsive to the control mechanisms that normally govern proliferation and differentiation. Mesothelioma is a rare form of cancer in which malignant (cancerous) cells are found in the mesothelium, a protective sac that covers most of the body's internal organs. The mesothelium is a membrane that covers and protects most of the internal organs of the body. It is composed of two layers of cells: one layer immediately surrounds the organ; the other forms a sac around it. The mesothelium produces a lubricating fluid that is released between these layers, allowing moving organs (such as the beating heart and the expanding and contracting lungs) to glide easily against adjacent structures. The mesothelium has different names, depending on its location in the body. The peritoneum is the mesothelial tissue that covers most of the organs in the abdominal cavity. The pleura is the membrane that surrounds the lungs and lines the wall of the chest cavity. The pericardium covers and protects the heart. The mesothelial tissue surrounding the male internal reproductive organs is called the tunica vaginalis testis. The tunica serosa uteri covers the internal reproductive organs in women. Most cases of mesothelioma begin in the pleura or peritoneum.
[0006] Although reported incidence rates have increased in the past 20 years, mesothelioma is still a relatively rare cancer. About 2,000 new cases of mesothelioma are diagnosed in the United States each year. Mesothelioma occurs more often in men than in women and risk increases with age, but this disease can appear in either men or women at any age.
[0007] Shortness of breath and pain in the chest due to an accumulation of fluid in the pleura are often symptoms of pleural mesothelioma. Symptoms of peritoneal mesothelioma include weight loss and abdominal pain and swelling due to a buildup of fluid in the abdomen. Other symptoms of peritoneal mesothelioma may include bowel obstruction, blood clotting abnormalities, anemia, and fever. If the cancer has spread beyond the mesothelium to other parts of the body, symptoms may include pain, trouble swallowing, or swelling of the neck or face.
[0008] For many years there have been two principal strategies for chemotherapeutic treatment of cancer: a) blocking hormone-dependent tumor cell proliferation by interference with the production or peripheral action of sex hormones; and b) killing cancer cells directly by exposing them to cytotoxic substances, which injure both neoplastic and normal cell populations.
[0009] Cancer therapy is also being attempted by the induction of terminal differentiation of the neoplastic cells (1). In cell culture models differentiation has been reported by exposure of cells to a variety of stimuli, including: cyclic AMP and retinoic acid (2,3), aclarubicin and other anthracyclines (4).
[0010] Despite many advances in the field of oncology, the majority of solid tumors remain incurable in the advanced stages. Cytotoxic therapy is used in most cases, however, it often causes significant morbidity to the patient without significant clinical benefit. Less toxic and more specific agents to treat and control advanced malignancies are being explored.
[0011] There is abundant evidence that neoplastic transformation does not necessarily destroy the potential of cancer cells to differentiate (1,5,6). There are many examples of tumor cells which do not respond to the normal regulators of proliferation and appear to be blocked in the expression of their differentiation program, and yet can be induced to differentiate and cease replicating. A variety of agents, including some relatively simple polar compounds (5,7-9), derivatives of vitamin D and retinoic acid (10-12), steroid hormones (13), growth factors (6,14), proteases (15,16), tumor promoters (17,18), and inhibitors of DNA or RNA synthesis (4,19-24), can induce various transformed cell lines and primary human tumor explants to express more differentiated characteristics.
[0012] Early studies identified a series of polar compounds that were effective inducers of differentiation in a number of transformed cell lines (8,9). Of these, the most effective inducer was the hybrid polar/apolar compound N,N′-hexamethylene bisacetamide (HMBA) (9). The use of this polar/apolar compound to induce murine erythroleukemia cells (MELC) to undergo erythroid differentiation with suppression of oncogenicity has proved a useful model to study inducer-mediated differentiation of transformed cells (5,7-9). HMBA-induced MELC terminal erythroid differentiation is a multi-step process. Upon addition of HMBA to MELC (745A-DS19) in culture, there is a latent period of 10 to 12 hours before commitment to terminal differentiation is detected. Commitment is defined as the capacity of cells to express terminal differentiation despite removal of inducer (25). Upon continued exposure to HMBA there is progressive recruitment of cells to differentiate. The present inventors have reported that MELC cell lines made resistant to relatively low levels of vincristine become markedly more sensitive to the inducing action of HMBA and can be induced to differentiate with little or no latent period (26).
[0013] HMBA is capable of inducing phenotypic changes consistent with differentiation in a broad variety of cells lines (5). The characteristics of the drug-induced effect have been most extensively studied in the murine erythroleukemia cell system (MELC) (5,25,27,28). MELC induction of differentiation is both time and concentration dependent. The minimum concentration required to demonstrate an effect in vitro in most strains is 2 to 3 mM; the minimum duration of continuous exposure generally required to induce differentiation in a substantial portion (>20%) of the population without continuing drug exposure is about 36 hours.
[0014] The primary target of action of HMBA is not known. There is evidence that protein kinase C is involved in the pathway of inducer-mediated differentiation (29). The in vitro studies provided a basis for evaluating the potential of HMBA as a cytodifferentiation agent in the treatment of human cancers (30). Several phase I clinical trials with HMBA have been completed (31-36). Clinical trials have shown that this compound can induce a therapeutic response in patients with cancer (35,36). However, these phase I clinical trials also have demonstrated that the potential efficacy of HMBA is limited, in part, by dose-related toxicity which prevents achieving optimal blood levels and by the need for intravenous administration of large quantities of the agent, over prolonged periods.
[0015] It has been reported that a number of compounds related to HMBA with polar groups separated by apolar linkages that, on a molar basis, are as active (37) or 100 times more active than HMBA (38). As a class, however, it has been found that the symmetrical dimers such as HMBA and related compounds are not the best cytodifferentiating agents.
[0016] It has unexpectedly been found that the best compounds comprise two polar end groups separated by a flexible chain of methylene groups, wherein one or both of the polar end groups is a large hydrophobic group. Preferably, the polar end groups are different and only one is a large hydrophobic group. These compounds are unexpectedly a thousand times more active than HMBA and ten times more active than HMBA related compounds.
[0017] Histone deacetylase inhibitors such as suberoylanilide hydroxamide acid (SAHA), belong to this class of agents that have the ability to induce tumor cell growth arrest, differentiation and/or apoptosis (39). These compounds are targeted towards mechanisms inherent to the ability of a neoplastic cell to become malignant, as they do not appear to have toxicity in doses effective for inhibition of tumor growth in animals (40). There are several lines of evidence that histone acetylation and deacetylation are mechanisms by which transcriptional regulation in a cell is achieved (41). These effects are thought to occur through changes in the structure of chromatin by altering the affinity of histone proteins for coiled DNA in the nucleosome. There are five types of histones that have been identified (designated H1, H2A, H2B, H3 and H4). Histones H2A, H2B, H3 and H4 are found in the nucleosomes and H1 is a linker located between nucleosomes. Each nucleosome contains two of each histone type within its core, except for H1, which is present singly in the outer portion of the nucleosome structure. It is believed that when the histone proteins are hypoacetylated, there is a greater affinity of the histone to the DNA phosphate backbone This affinity causes DNA to be tightly bound to the histone and renders the DNA inaccessible to transcriptional regulatory elements and machinery. The regulation of acetylated states occurs through the balance of activity between two enzyme complexes, histone acetyl transferase (HAT) and histone deacetylase (HDAC). The hypoacetylated state is thought to inhibit transcription of associated DNA. This hypoacetylated state is catalyzed by large multiprotein complexes that include HDAC enzymes. In particular, HDACs have been shown to catalyze the removal of acetyl groups from the chromatin core histones.
[0018] The inhibition of HDAC by SAHA is thought occur through direct interaction with the catalytic site of the enzyme as demonstrated by X-ray crystallography studies (42). The result of HDAC inhibition is not believed to have a generalized effect on the genome, but rather, only affects a small subset of the genome (43). Evidence provided by DNA microarrays using malignant cell lines cultured with a HDAC inhibitor shows that there are a finite (1-2%) number of genes whose products are altered. For example, cells treated in culture with HDAC inhibitors show a consistent induction of the cyclin-dependent kinase inhibitor p21 (44). This protein plays an important role in cell cycle arrest. HDAC inhibitors are thought to increase the rate of transcription of p21 by propagating the hyperacetylated state of histones in the region of the p21 gene, thereby making the gene accessible to transcriptional machinery. Genes whose expression is not affected by HDAC inhibitors do not display changes in the acetylation of regional associated histones (45).
[0019] It has been shown in several instances that the disruption of HAT or HDAC activity is implicated in the development of a malignant phenotype. For instance, in acute promyelocytic leukemia, the oncoprotein produced by the fusion of PML and RAR alpha appears to suppress specific gene transcription through the recruitment of HDACs (46). In this manner, the neoplastic cell is unable to complete differentiation and leads to excess proliferation of the leukemic cell line.
[0020] U.S. Pat. Nos. 5,369,108, 5,932,616, 5,700,811, 6,087,367 and 6,511,990, issued to some of the present inventors, disclose compounds useful for selectively inducing terminal differentiation of neoplastic cells, which compounds have two polar end groups separated by a flexible chain of methylene groups or a by a rigid phenyl group, wherein one or both of the polar end groups is a large hydrophobic group. Some of the compounds have an additional large hydrophobic group at the same end of the molecule as the first hydrophobic group which further increases differentiation activity about 100 fold in an enzymatic assay and about 50 fold in a cell differentiation assay. Methods of synthesizing the compounds used in the methods and pharmaceutical compositions of this invention are fully described the aforementioned patents, the entire contents of which are incorporated herein by reference.
[0021] In addition to their biological activity as antitumor agents, the compounds disclosed in the aforementioned patents have recently been identified as useful for treating or preventing a wide variety of thioredoxin (TRX)-mediated diseases and conditions, such as inflammatory diseases, allergic diseases, autoimmune diseases, diseases associated with oxidative stress of diseases characterized by cellulora hyperproliferation (U.S. application Ser. No. 10/369,094, filed Feb. 15, 2003. Further, these compounds have been identified as useful for treating diseases of the central nervous system (CNS) such as neurodegenerative diseases and for treating brain cancer (See, U.S. application Ser. No. 10.273,401, filed Oct. 16, 2002).
[0022] The aforementioned patents do not disclose specific oral formulations of the HDAC inhibitors or specific dosages and dosing schedules of the recited compounds. Importantly, the aforementioned patents do not disclose oral formulations that have favorable pharmacokinetic profiles such as high bioavailability which gives rise to high blood levels of the active compounds over an extended period of time.
[0023] The class of compounds of the present invention may be useful for selectively inducing terminal differentiation, cell growth arrest and/or apoptosis of neoplastic cells and therefore aid in treatment of cancer in patients. There is an urgent need to discover suitable dosages and dosing schedules of these compounds, and to develop formulations, preferably oral formulations, which give rise to steady, therapeutically effective blood levels of the active compounds over an extended period of time.
[0024] The present invention provides a method of treating mesothelioma by administering an effective amount of an HDAC inhibitor, such as suberoylanilide hydroxamic acid (SAHA). SAHA can be administered in a total daily dose of up to 800 mg, preferably orally, once, twice or three times daily, continuously (every day) or intermittently (e.g., 3-5 days a week).
[0025] Oral SAHA has been safely administered in phase I clinical studies to patients suffering from mesothelioma.
[0026] Furthermore, the present invention provides a method of treating mesothelioma by administering an effective amount of an HDAC inhibitor as described herein. In one embodiment, the HDAC inhibitor is a hydroxamic acid derivative HDAC inhibitor. The HDAC inhibitors can be administered in a total daily dose of up to 800 mg, preferably orally, once, twice or three times daily, continuously (i.e., every day) or intermittently (e.g., 3-5 days a week).
[0027] The present invention also provides methods for selectively inducing terminal differentiation, cell growth arrest and/or apoptosis of neoplastic cells, thereby inhibiting proliferation of such cells, as well as methods of treating mesothelioma and of chemoprevention in subjects in need thereof, by administering to said subject an effective amount of a pharmaceutical composition comprising a HDAC inhibitor or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or diluent. An effective amount of an HDAC inhibitor in the present invention can be up to a total daily dose of 800 mg.
[0028] In one embodiment, the HDAC inhibitor is suberoylanilide hydroxamic acid (SAHA), represented by the structure:
[0029] In another embodiment, the HDAC inhibitor is pyroxamide, represented by the structure:
[0030] In another embodiment, the HDAC inhibitor is represented by the structure:
[0031] wherein R
[0032] In another embodiment, the HDAC inhibitor is represented by the structure:
[0033] wherein R is a substituted or unsubstituted phenyl, piperidine, thiazole, 2-pyridine, 3-pyridine or 4-pyridine and n is an integer from 4 to 8.
[0034] In another embodiment, the HDAC inhibitor is represented by the structure:
[0035] wherein A is an amide moiety, R
[0036] In another embodiment, the HDAC inhibitor is a hydroxamic acid derivative selected from the group consisting of m-carboxycinnamic acid bishydroxamide (CBHA), Trichostatin A (TSA), Trichostatin C, Salicylihydroxamic Acid (SBHA), Azelaic Bishydroxamic Acid (ABHA), Azelaic-1-Hydroxamate-9-Anilide (AAHA), 6-(3-Chlorophenylureido)carpoic Hydroxamic Acid (3Cl-UCHA), Oxamflatin, A-161906, Scriptaid, PXD-101, LAQ-824, CHAP, MW2796, and MW2996.
[0037] In another embodiment, the HDAC inhibitor is a cyclic tetrapeptide such as trapoxin A (TPX)-cyclic tetrapeptide (cyclo-(L-phenylalanyl-L-phenylalanyl-D-pipecolinyl-L-2-amin
o-8-oxo-9,10-epoxy decanoyl); FR901228 (FK 228, depsipeptide); FR
[0038] In another embodiment, the HDAC inhibitor is a Short Chain Fatty Acid derivative (SCFA) such as Sodium Butyrate, Isovalerate, Valerate, 4-Phenylbutyrate (4-PBA), Phenylbutyrate (PB), Propionate, Butyramide, Isobutyramide, Phenylacetate, 3-Bromopropionate, Tributyrin, Valproic acid, Valproate and Pivanex™.
[0039] In another embodiment, the HDAC inhibitor is a benzamide derivative such as CI-994; MS-275 [N-(2-aminophenyl)-4-[N-(pyridin-3-ylmethoxycarbonyl)aminome thyl]benzamide]; and 3′-amino derivative of MS-275.
[0040] In another embodiment, the HDAC inhibitor is an electrophilic ketone derivative such as trifluoromethyl ketones and α-keto amides such as N-methyl-α-ketoamides
[0041] In yet another embodiment, the HDAC inhibitor is Depudecin.
[0042] In one embodiment, the pharmaceutical compositions comprising the HDAC inhibitor are administered orally, for example within a gelatin capsule. In a further embodiment, the pharmaceutical compositions are further comprised of microcrystalline cellulose, croscarmellose sodium and magnesium stearate.
[0043] The HDAC inhibitors can be administered in a total daily dose which may vary from patient to patient, and may be administered at varying dosage schedules. Suitable dosages are total daily dosage of between about 25-4000 mg/m
[0044] In one embodiment, the composition is administered once daily at a dose of about 200-600 mg. In another embodiment, the composition is administered twice daily at a dose of about 200-400 mg. In another embodiment, the composition is administered twice daily at a dose of about 200-400 mg intermittently, for example three, four or five days per week. In one embodiment, the daily dose is 200 mg which can be administered once-daily, twice-daily or three-times daily. In one embodiment, the daily dose is 300 mg which can be administered once-daily, twice-daily or three-times daily. In one embodiment, the daily dose is 400 mg which can be administered once-daily, twice-daily or three-times daily.
[0045] The present invention further provides a safe, daily dosing regimen of the formulation of pharmaceutical compositions comprising an HDAC inhibitor which are easy to follow and to adhere to. These pharmaceutical compositions are suitable for oral administration and comprise a compound useful for treating cancer, e.g. mesothelioma, chemoprevention, selectively inducing terminal differentiation, cell growth arrest and/or apoptosis of neoplastic cells, and/or which is a potent inhibitor of histone deacetylase (HDAC).
[0046] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
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[0055] FIGS.
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[0060] The present invention relates to a method of treating mesothelioma in a subject, comprising the step of administering to the subject an effective amount of a pharmaceutical composition comprising histone deacetylase (HDAC) inhibitor, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or diluent, wherein the amount of histone deacetylase inhibitor is effective to treat mesothelioma in the subject. In one embodiment, the HDAC inhibitor is a hydroxamic acid derivative as described herein. In another embodiment, the HDAC inhibitor is a benzamide derivative as described herein. In another embodiment, the HDAC inhibitor is a cyclic tetrapeptide as described herein. In another embodiment, the HDAC inhibitor is a Short Chain Fatty Acid (SCFA) as described herein. In another embodiment, the HDAC inhibitor is an electrophillic ketone as described herein. In another embodiment, the HDAC inhibitor is depudecin.
[0061] In another embodiment, the present invention relates to a method of treating mesothelioma in a subject, comprising the step of administering to the subject an effective amount of a pharmaceutical composition comprising suberoylanilide hydroxamic acid (SAHA), or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or diluent, wherein the amount of SAHA is effective to treat mesothelioma in the subject.
[0062] In another embodiment, the present invention relates to a method of treating mesothelioma in a subject, comprising the step of administering to the subject an effective amount of a pharmaceutical composition comprising a histone deacetylase (HDAC) inhibitor represented by any of the structure described herein as by formulas 1-51 described herein, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or diluent, wherein the amount of the histone deacetylase inhibitor is effective to treat mesothelioma in the subject.
[0063] The HDAC inhibitor can be administered once daily (QD), or divided into multiple daily doses such as twice daily (BID), and three times daily (TID). The HDAC inhibitor can be administered at a total daily dosage of up to 800 mg, e.g., 200 mg, 300 mg, 400 mg, 600 mg or 800 mg, which can be administered in one daily dose or can be divided into multiple daily doses as described above.
[0064] In addition, the administration can be continuous, i.e., every day, or intermittently. The terms “intermittent” or “intermittently” as used herein means stopping and starting at either regular or irregular intervals. For example, intermittent administration of an HDAC inhibitor may be administration one to six days per week or it may mean administration in cycles (e.g. daily administration for two to eight consecutive weeks, then a rest period with no administration for up to one week) or it may mean administration on alternate days.
[0065] SAHA or any of the HDAC inhibitors are administered to the patient at a total daily dosage of between 25-4000 mg/m
[0066] Another currently preferred treatment protocol comprises intermittent administration of between three to five days a week, once, twice or three times daily at a total daily dose in the range of about 200 mg to about 600 mg.
[0067] In one particular embodiment, the HDAC inhibitor is administered continuously once daily at a dose of 400 mg or twice daily at a dose of 200 mg.
[0068] In another particular embodiment, the HDAC inhibitor is administered intermittently three days a week, once daily at a dose of 400 mg or twice daily at a dose of 200 mg.
[0069] In another particular embodiment, the HDAC inhibitor is administered intermittently four days a week, once daily at a dose of 400 mg or twice daily at a dose of 200 mg.
[0070] In another particular embodiment, the HDAC inhibitor is administered intermittently five days a week, once daily at a dose of 400 mg or twice daily at a dose of 200 mg.
[0071] In one particular embodiment, the HDAC inhibitor is administered continuously once daily at a dose of 600 mg, twice daily at a dose of 300 mg, or three times daily at a dose of 200 mg.
[0072] In another particular embodiment, the HDAC inhibitor is administered intermittently three days a week, once daily at a dose of 600 mg, twice daily at a dose of 300 mg, or three times daily at a dose of 200 mg.
[0073] In another particular embodiment, the HDAC inhibitor is administered intermittently four days a week, once daily at a dose of 600 mg, twice daily at a dose of 300 mg, or three times daily at a dose of 200 mg.
[0074] In another particular embodiment, the HDAC inhibitor is administered intermittently five days a week, once daily at a dose of 600 mg, twice daily at a dose of 300 mg, or three times daily at a dose of 200 mg.
[0075] In addition, the HDAC inhibitor may be administered according to any of the schedules described above, consecutively for a few weeks, followed by a rest period. For example, the HDAC inhibitor may be administered according to any one of the schedules described above from two to eight weeks, followed by a rest period of one week, or twice daily at a dose of 300 mg for three to five days a week. In another particular embodiment, the HDAC inhibitor is administered three times daily for two consecutive weeks, followed by one week of rest.
[0076] It should be apparent to a person skilled in the art that the various dosages and dosing schedules described herein merely set forth specific embodiments and should not be construed as limiting the broad scope of the invention. Any permutations, variations and combinations of the dosages and dosing schedules are included within the scope of the present invention.
[0077] The compositions of the present invention may be formulated in any unit dosage form (liquid or solid) suited for oral administration, for example, in the form of a pellet, a tablet, a coated tablet, a capsule, a gelatin capsule, a solution, a suspension, or a dispersion. In a currently preferred embodiment, the composition is in the form of a gelatin capsule.
[0078] Any inert excipient that is commonly used as a carrier or diluent may be used in the formulations of the present invention, such as for example, a gum, a starch, a sugar, a cellulosic material, an acrylate, or mixtures thereof. A preferred diluent is microcrystalline cellulose. The compositions may further comprise a disintegrating agent (e.g., sodium croscarmellose) and a lubricant (e.g., magnesium stearate), and in addition may comprise one or more additives selected from a binder, a buffer, a protease inhibitor, a surfactant, a solubilizing agent, a plasticizer, an emulsifier, a stabilizing agent, a viscosity increasing agent, a sweetener, a film forming agent, or any combination thereof. Furthermore, the compositions of the present invention may be in the form of controlled release or immediate release formulations.
[0079] The present invention further provides a safe, daily dosing regimen of these formulations, which is easy to follow and to adhere to. The formulations of the present invention are useful for selectively inducing terminal differentiation, cell growth arrest and/or apoptosis of neoplastic cells and therefore aid in treatment of tumors in patients.
[0080] The term “treating” in its various grammatical forms in relation to the present invention refers to preventing (i.e. chemoprevention), curing, reversing, attenuating, alleviating, minimizing, suppressing or halting the deleterious effects of a disease state, disease progression, disease causative agent (e.g., bacteria or viruses) or other abnormal condition. For example, treatment may involve alleviating a symptom (i.e., not necessary all symptoms) of a disease or attenuating the progression of a disease. Because some of the inventive methods involve the physical removal of the etiological agent, the artisan will recognize that they are equally effective in situations where the inventive compound is administered prior to, or simultaneous with, exposure to the etiological agent (prophylactic treatment) and situations where the inventive compounds are administered after (even well after) exposure to the etiological agent.
[0081] Although the methods of the present invention can be practiced in vitro, it is contemplated that the preferred embodiment for the methods of selectively inducing terminal differentiation, cell growth arrest and/or apoptosis of neoplastic cells will comprise contacting the cells in vivo, i.e., by administering the compounds to a subject harboring neoplastic cells or tumor cells in need of treatment.
[0082] The methods of the present invention may also comprise initially administering to the subject an antitumor agent so as to render the neoplastic cells in the subject resistant to an antitumor agent and subsequently administering an effective amount of any of the compositions of the present invention, effective to selectively induce terminal differentiation, cell growth arrest and/or apoptosis of such cells, or to treat cancer or provide chemoprevention.
[0083] The antitumor agent may be one of numerous chemotherapy agents such as an alkylating agent, an antimetabolite, a hormonal agent, an antibiotic, colchicine, a vinca alkaloid, L-asparaginase, procarbazine, hydroxyurea, mitotane, nitrosoureas or an imidazole carboxamide. Suitable agents are those agents that promote depolarization of tubulin. Preferably the antitumor agent is colchicine or a vinca alkaloid; especially preferred are vinblastine and vincristine. In embodiments where the antitumor agent is vincristine, the cells preferably are treated so that they are resistant to vincristine at a concentration of about 5 mg/ml. The treating of the cells to render them resistant to an antitumor agent may be effected by contacting the cells with the agent for a period of at least 3 to 5 days. The contacting of the resulting cells with any of the compounds above is performed as described previously. In addition to the above chemotherapy agents, the compounds may also be administered together with radiation therapy.
[0084] In one embodiment, the invention relates to a method of treating cancer in a subject in need of treatment comprising administering to said subject a therapeutically effective amount of a histone deacetylase inhibitor described herein. The term “cancer” refers to any cancer caused by the proliferation of neoplastic cells, such as tumors, neoplasms, carcinomas, sarcomas, leukemias, lymphomas and the like. For example, cancers include, but are not limited to, mesothelioma, leukemias and lymphomas such as cutaneous T-cell lymphomas (CTCL), noncutaneous peripheral T-cell lymphomas, lymphomas associated with human T-cell lymphotrophic virus (HTLV) such as adult T-cell leukemia/lymphoma (ATLL) acute lymphocytic leukemia, acute nonlymphocytic leukemias, chronic lymphocytic leukemia, chronic myelogenous leukemia, Hodgkin's disease, non-Hodgkin's lymphomas, and multiple myeloma, childhood solid tumors such as brain tumors, neuroblastoma, retinoblastoma, Wilms' tumor, bone tumors, and soft-tissue sarcomas, common solid tumors of adults such as head and neck cancers (e.g., oral, laryngeal and esophageal), genito urinary cancers (e.g., prostate, bladder, renal, uterine, ovarian, testicular, rectal and colon), lung cancer, breast cancer, pancreatic cancer, melanoma and other skin cancers, stomach cancer, brain tumors, liver cancer and thyroid cancer. As demonstrated herein, the HDAC inhibitors are useful for the treatment of mesothelioma.
[0085] The method of the present invention is intended for the treatment or chemoprevention of human patients with cancer. However, it is also likely that the method would be effective in the treatment of cancer in other mammals.
[0086] Histone deacetylases (HDACs), as that term is used herein, are enzymes that catalyze the removal of acetyl groups from lysine residues in the amino terminal tails of the nucleosomal core histones. As such, HDACs together with histone acetyl transferases (HATs) regulate the acetylation status of histones. Histone acetylation affects gene expression and inhibitors of HDACs, such as the hydroxamic acid-based hybrid polar compound suberoylanilide hydroxamic acid (SAHA) induce growth arrest, differentiation and/or apoptosis of transformed cells in vitro and inhibit tumor growth in vivo. HDACs can be divided into three classes based on structural homology. Class I HDACs (HDACs 1, 2, 3 and 8) bear similarity to the yeast RPD3 protein, are located in the nucleus and are found in complexes associated with transcriptional co-repressors. Class II HDACs (HDACs 4, 5, 6, 7 and 9) are similar to the yeast HDA1 protein, and have both nuclear and cytoplasmic subcellular localization. Both Class I and II HDACs are inhibited by hydroxamic acid-based HDAC inhibitors, such as SAHA. Class III HDACs form a structurally distant class of NAD dependent enzymes that are related to the yeast SIR2 proteins and are not inhibited by hydroxamic acid-based HDAC inhibitors.
[0087] Histone deacetylase inhibitors or HDAC inhibitors, as that term is used herein are compounds that are capable of inhibiting the deacetylation of histones in vivo, in vitro or both. As such, HDAC inhibitors inhibit the activity of at least one histone deacetylase. As a result of inhibiting the deacetylation of at least one histone, an increase in acetylated histone occurs and accumulation of acetylated histone is a suitable biological marker for assessing the activity of HDAC inhibitors. Therefore, procedures that can assay for the accumulation of acetylated histones can be used to determine the HDAC inhibitory activity of compounds of interest. It is understood that compounds that can inhibit histone deacetylase activity can also bind to other substrates and as such can inhibit other biologically active molecules such as enzymes. It is also to be understood that the compounds of the present invention are capable of inhibiting any of the histone deacetylases set forth above, or any other histone deacetylases.
[0088] For example, in patients receiving HDAC inhibitors, the accumulation of acetylated histones in peripheral mononuclear cells as well as in tissue treated with HDAC inhibitors can be determined against a suitable control.
[0089] HDAC inhibitory activity of a particular compound can be determined in vitro using, for example, an enzymatic assays which shows inhibition of at least one histone deacetylase. Further, determination of the accumulation of acetylated histones in cells treated with a particular composition can be determinative of the HDAC inhibitory activity of a compound.
[0090] Assays for the accumulation of acetylated histones are well known in the literature. See, for example, Marks, P. A. et al., J. Natl. Cancer Inst., 92:1210-1215, 2000, Butler, L. M. et al., Cancer Res. 60:5165-5170 (2000), Richon, V. M. et al., Proc. Natl. Acad. Sci., USA, 95:3003-3007, 1998, and Yoshida, M. et al., J. Biol. Chem., 265:17174-17179, 1990.
[0091] For example, an enzymatic assay to determine the activity of a histone deacetylase inhibitor compound can be conducted as follows. Briefly, the effect of an HDAC inhibitor compound on affinity purified human epitope-tagged (Flag) HDAC1 can be assayed by incubating the enzyme preparation in the absence of substrate on ice for about 20 minutes with the indicated amount of inhibitor compound. Substrate ([
[0092] In vivo studies can be conducted as follows. Animals, for example, mice, can be injected intraperitoneally with an HDAC inhibitor compound. Selected tissues, for example, brain, spleen, liver etc, can be isolated at predetermined times, post administration. Histones can be isolated from tissues essentially as described by Yoshida et al., J. Biol. Chem. 265:17174-17179, 1990. Equal amounts of histones (about 1 μg) can be electrophoresed on 15% SDS-polyacrylamide gels and can be transferred to Hybond-P filters (available from Amersham). Filters can be blocked with 3% milk and can be probed with a rabbit purified polyclonal anti-acetylated histone H4 antibody (αAc-H4) and antiacetylated histone H3 antibody (αAc-H3) (Upstate Biotechnology, Inc.). Levels of acetylated histone can be visualized using a horseradish peroxidase-conjugated goat anti-rabbit antibody (1:5000) and the SuperSignal chemiluminescent substrate (Pierce). As a loading control for the histone protein, parallel gels can be run and stained with Coomassie Blue (CB).
[0093] In addition, hydroxamic acid-based HDAC inhibitors have been shown to up regulate the expression of the p21
[0094] Typically, HDAC inhibitors fall into five general classes: 1) hydroxamic acid derivatives; 2) Short-Chain Fatty Acids (SCFAs); 3) cyclic tetrapeptides; 4) benzamides; and 5) electrophilic ketones.
[0095] Thus, the present invention includes within its broad scope compositions comprising HDAC inhibitors which are 1) hydroxamic acid derivatives; 2) Short-Chain Fatty Acids (SCFAs); 3) cyclic tetrapeptides; 4) benzamides; 5) electrophilic ketones; and/or any other class of compounds capable of inhibiting histone deacetylases, for use in inhibiting histone deacetylase, inducing terminal differentiation in neoplastic cells, and/or inducing differentiation of tumor cells in a tumor.
[0096] Examples of such HDAC inhibitors include, but are not limited to:
[0097] A. Hydroxamic Acid Derivatives such as suberoylanilide hydroxamic acid (SAHA) (Richon et al., Proc. Natl. Acad. Sci. USA 95,3003-3007 (1998)); m-carboxycinnamic acid bishydroxamide (CBHA) (Richon et al., supra); pyroxamide; trichostatin analogues such as trichostatin A (TSA) and trichostatin C (Koghe et al. 1998. Biochem. Pharmacol. 56: 1359-1364); salicylihydroxamic acid (SBHA) (Andrews et al., International J. Parasitology 30,761-768 (2000)); suberoyl bishydroxamic acid (SBHA) (U.S. Pat. No. 5,608,108); azelaic bishydroxamic acid (ABHA) (Andrews et al., supra); azelaic-1-hydroxamate-9-anilide (AAHA) (Qiu et al., Mol. Biol. Cell 11, 2069-2083 (2000)); 6-(3-chlorophenylureido)carpoic hydroxamic acid (3Cl-UCHA); oxamflatin [(2E)-5-[3[-(phenylsufonyl)aminol phenyl]-pent-2-en-4-ynohydroxamic acid] (Kim et al. Oncogene, 18: 2461 2470 (1999)); A-161906, Scriptaid (Su et al. 2000 Cancer Research, 60: 3137-3142); PXD-101 (Prolifix); LAQ-824; CHAP; MW2796 (Andrews et al., supra); MW2996 (Andrews et al., supra); or any of the hydroxamic acids disclosed in U.S. Pat. Nos. 5,369,108, 5,932,616, 5,700,811, 6,087,367 and 6,511,990.
[0098] B. Cyclic Tetrapeptides such as trapoxin A (TPX)-cyclic tetrapeptide (cyclo-(L-phenylalanyl-L-phenylalanyl-D-pipecolinyl-L-2-amin o-8-oxo-9,10-epoxy decanoyl)) (Kijima et al., J Biol. Chem. 268,22429-22435 (1993)); FR901228 (FK 228, depsipeptide) (Nakajima et al., Ex. Cell Res. 241,126-133 (1998)); FR225497 cyclic tetrapeptide (H. Mori et al., PCT Application WO 00/08048 (17 Feb. 2000)); apicidin cyclic tetrapeptide [cyclo(N—O-methyl-L-tryptophanyl-L-isoleucinyl-D-pipecolin yl-L-2-amino-8-oxodecanoyl)] (Darkin-Rattray et al., Proc. Natl. Acad. Sci. USA 93,1314313147 (1996)); apicidin Ia, apicidin Ib, apicidin Ic, apicidin IIa, and apicidin IIb (P. Dulski et al., PCT Application WO 97/11366); CHAP, HC-toxin cyclic tetrapeptide (Bosch et al., Plant Cell 7, 1941-1950 (1995)); WF27082 cyclic tetrapeptide (PCT Application WO 98/48825); and chlamydocin (Bosch et al., supra).
[0099] C. Short chain fatty acid (SCFA) derivatives such as: sodium butyrate (Cousens et al., J. Biol. Chem. 254,1716-1723 (1979)); isovalerate (McBain et al., Biochem. Pharm. 53: 1357-1368 (1997)); valerate (McBain et al., supra); 4-phenylbutyrate (4-PBA) (Lea and Tulsyan, Anticancer Research, 15,879-873 (1995)); phenylbutyrate (PB) (Wang et al., Cancer Research, 59, 2766-2799 (1999)); propionate (McBain et al., supra); butyramide (Lea and Tulsyan, supra); isobutyramide (Lea and Tulsyan, supra); phenylacetate (Lea and Tulsyan, supra); 3-bromopropionate (Lea and Tulsyan, supra); tributyrin (Guan et al., Cancer Research, 60,749-755 (2000)); valproic acid, valproate and Pivanex™.
[0100] D. Benzamide derivatives such as CI-994; MS-275 [N-(2-aminophenyl)-4-[N-(pyridin-3-yl methoxycarbonyl)aminomethyl]benzamide] (Saito et al., Proc. Natl. Acad. Sci. USA 96, 4592-4597 (1999)); and 3′-amino derivative of MS-275 (Saito et al., supra).
[0101] E. Electrophilic ketone derivatives such as trifluoromethyl ketones (Frey et al, Bioorganic & Med. Chem. Lett. (2002), 12, 3443-3447; U.S. Pat. No. 6,511,990) and α-keto amides such as N-methyl-α-ketoamides
[0102] F. Other HDAC Inhibitors such as depudecin (Kwon et al. 1998. PNAS 95: 3356-3361.
[0103] Preferred hydroxamic acid based HDAC inhibitors are suberoylanilide hydroxamic acid (SAHA), m-carboxycinnamic acid bishydroxamate (CBHA) and pyroxamide. SAHA has been shown to bind directly in the catalytic pocket of the histone deacetylase enzyme. SAHA induces cell cycle arrest, differentiation and/or apoptosis of transformed cells in culture and inhibits tumor growth in rodents. SAHA is effective at inducing these effects in both solid tumors and hematological cancers. It has been shown that SAHA is effective at inhibiting tumor growth in animals with no toxicity to the animal. The SAHA-induced inhibition of tumor growth is associated with an accumulation of acetylated histones in the tumor. SAHA is effective at inhibiting the development and continued growth of carcinogen-induced (N-methylnitrosourea) mammary tumors in rats. SAHA was administered to the rats in their diet over the 130 days of the study. Thus, SAHA is a nontoxic, orally active antitumor agent whose mechanism of action involves the inhibition of histone deacetylase activity.
[0104] Preferred HDAC inhibitors are those disclosed in U.S. Pat. Nos. 5,369,108, 5,932,616, 5,700,811, 6,087,367 and 6,511,990, issued to some of the present inventors disclose compounds, the entire contents of which are incorporated herein by reference, non-limiting examples of which are set forth below:
[0105] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 1, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0106] wherein R
[0107] In a particular embodiment of formula 1, R
[0108] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 2, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0109] wherein each of R
[0110] In a particular embodiment of formula 2, each of R
[0111] In another particular embodiment of formula 2, n is 6. In yet another embodiment of formula 2, R
[0112] In another embodiment of formula 2, n is 6, R
[0113] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 3, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0114] wherein n is an integer from 5 to about 8.
[0115] In a preferred embodiment of formula 3, n is 6. In accordance with this embodiment, the HDAC inhibitor is SAHA (4), or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient. SAHA can be represented by the following structural formula:
[0116] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 5, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0117] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 6 (pyroxamide), or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0118] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 7, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0119] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 8, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0120] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 9, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0121] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 10, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0122] wherein R
[0123] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 11, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0124] wherein R
[0125] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 12, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0126] wherein each of X and Y are independently the same as or different from each other and are a hydroxyl, amino or hydroxylamino group, a substituted or unsubstituted alkyloxy, alkylamino, dialkylamino, arylamino, alkylarylamino, alkyloxyamino, aryloxyamino, alkyloxyalkylamino, or aryloxyalkylamino group; R is a hydrogen atom, a hydroxyl, group, a substituted or unsubstituted alkyl, arylalkyloxy, or aryloxy group; and each of m and n are independently the same as or different from each other and are each an integer from about 0 to about 8.
[0127] In a particular embodiment, the HDAC inhibitor is a compound of formula 12 wherein X, Y and R are each hydroxyl and both m and n are 5.
[0128] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 13, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0129] wherein each of X and Y are independently the same as or different from each other and are a hydroxyl, amino or hydroxylamino group, a substituted or unsubstituted alkyloxy, alkylamino, dialkylamino, arylamino, alkylarylamino, alkyloxyamino, aryloxyamino, alkyloxyalkylamino or aryloxyalkylamino group; each of R
[0130] In one particular embodiment of formula 13, each of X and Y is a hydroxyl group and each of R
[0131] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 14, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0132] wherein each of X and Y are independently the same as or different from each other and are a hydroxyl, amino or hydroxylamino group, a substituted or unsubstituted alkyloxy, alkylamino, dialkylamino, arylamino, alkylarylamino, alkyloxyamino, aryloxyamino, alkyloxyalkylamino or aryloxyalkylamino group; each of R
[0133] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 15, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0134] wherein each of X and Y are independently the same as or different from each other and are a hydroxyl, amino or hydroxylamino group, a substituted or unsubstituted alkyloxy, alkylamino, dialkylamino, arylamino, alkylarylamino, alkyloxyamino, aryloxyamino, alkyloxyalkylamino or aryloxyalkylamino group; and each of m and n are independently the same as or different from each other and are each an integer from about 0 to about 8.
[0135] In one particular embodiment of formula 15, each of X and Y is a hydroxyl group and each of m and n is 5.
[0136] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 16, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0137] wherein each of X and Y are independently the same as or different from each other and are a hydroxyl, amino or hydroxylamino group, a substituted or unsubstituted alkyloxy, alkylamino, dialkylamino, arylamino, alkylarylamino, alkyloxyamino, aryloxyamino, alkyloxyalkylamino or aryloxyalkylamino group; R
[0138] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 17, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0139] wherein each of X an Y are independently the same as or different from each other and are a hydroxyl, amino or hydroxylamino group, a substituted or unsubstituted alkyloxy, alkylamino, dialkylamino, arylamino, alkylarylamino, or aryloxyalkylamino group; and n is an integer from about 0 to about 8.
[0140] In one particular embodiment of formula 17, each of X and Y is a hydroxylamino group; R
[0141] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 18, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0142] wherein each of X and Y are independently the same as or different from each other and are a hydroxyl, amino or hydroxylamino group, a substituted or unsubstituted alkyloxy, alkylamino, dialkylamino, arylamino, alkylarylamino, alkyloxyamino, aryloxyamino, alkyloxyalkyamino or aryloxyalkylamino group; each of R
[0143] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 19, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0144] wherein each of R
[0145] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 20, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0146] wherein each of R
[0147] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 21, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0148] wherein each of R
[0149] In a particular embodiment, the HDAC inhibitor is a compound of structural formula 21 wherein R
[0150] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 22, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0151] wherein R is a phenylamino group substituted with a cyano, methylcyano, nitro, carboxyl, aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, trifluoromethyl, hydroxylaminocarbonyl, N-hydroxylaminocarbonyl, methoxycarbonyl, chloro, fluoro, methyl, methoxy, 2,3-difluoro, 2,4-difluoro, 2,5-difluoro, 2,6-difuloro, 3,5-difluoro, 2,3,6-trifluoro, 2,4,6-trifluoro, 1,2,3-trifluoro, 3,4,5-trifluoro, 2,3,4,5-tetrafluoro, or 2,3,4,5,6-pentafluoro group; and n is an integer from 4 to 8.
[0152] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 23 (m-carboxycinnamic acid bishydroxamide-CBHA), or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0153] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 24, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0154] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 25, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0155] wherein R is a substituted or unsubstituted phenyl, piperidine, thiazole, 2-pyridine, 3-pyridine or 4-pyridine and n is an integer from about 4 to about 8.
[0156] In one particular embodiment of formula 25, R is a substituted phenyl group. In another particular embodiment of formula 25, R is a substituted phenyl group, where the substituent is selected from the group consisting of methyl, cyano, nitro, thio, trifluoromethyl, amino, aminocarbonyl, methylcyano, chloro, fluoro, bromo, iodo, 2,3-difluoro, 2,4-difluoro, 2,5-difluoro, 3,4-difluoro, 3,5-difluoro, 2,6-difluoro, 1,2,3-trifluoro, 2,3,6-trifluoro, 2,4,6-trifluoro, 3,4,5-trifluoro, 2,3,5,6-tetrafluoro, 2,3,4,5,6-pentafluoro, azido, hexyl, t-butyl, phenyl, carboxyl, hydroxyl, methyloxy, phenyloxy, benzyloxy, phenylaminooxy, phenylaminocarbonyl, methyloxycarbonyl, methylaminocarbonyl, dimethylamino, dimethylaminocarbonyl, or hydroxylaminocarbonyl group.
[0157] In another particular embodiment of formula 25, R is a substituted or unsubstituted 2-pyridine, 3-pyridine or 4-pyridine and n is an integer from about 4 to about 8.
[0158] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 26, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0159] wherein R is a substituted or unsubstituted phenyl, pyridine, piperidine or thiazole group and n is an integer from about 4 to about 8 or a pharmaceutically acceptable salt thereof.
[0160] In a particular embodiment of formula 26, R is a substituted phenyl group. In another particular embodiment of formula 26, R is a substituted phenyl group, where the substituent is selected from the group consisting of methyl, cyano, nitro, thio, trifluoromethyl, amino, aminocarbonyl, methylcyano, chloro, fluoro, bromo, iodo, 2,3-difluoro, 2,4-difluoro, 2,5-difluoro, 3,4-difluoro, 3,5-difluoro, 2,6-difluoro, 1,2,3-trifluoro, 2,3,6-trifluoro, 2,4,6-trifluoro, 3,4,5-trifluoro, 2,3,5,6-tetrafluoro, 2,3,4,5,6-pentafluoro, azido, hexyl, t-butyl, phenyl, carboxyl, hydroxyl, methyloxy, phenyloxy, benzyloxy, phenylaminooxy, phenylaminocarbonyl, methyloxycarbonyl, methylaminocarbonyl, dimethylamino, dimethylaminocarbonyl, or hydroxylaminocarbonyl group.
[0161] In another particular embodiment of formula 26, R is phenyl and n is 5. In another embodiment, n is 5 and R is 3-chlorophenyl.
[0162] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 27, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.
[0163] wherein each of R
[0164] In certain embodiments of formula 27, R
[0165] In one embodiment, the HDAC inhibitor useful in the methods of the present invention is represented by the structure of formula 28, or a pharmaceutically acceptable salt or hydrate thereof, and a pharmaceutically acceptable carrier or excipient.