WO2007140299A2 - Use of ixabepilone in combination with cyp3a4 inhibitors for pharmaceuticals - Google Patents

Abstract

Disclosed are Uses of ixabepilone in combination with CYP3A4 inhibitors such as ketoconazole and lapatinib to achieve a surprisingly enhanced pharmacological effect as compared with when ixabepilone is administered unaccompanied by the CYP3A4 inhibitor. Also disclosed are methods of treating cancer in a human patient comprising administering to the human a therapeutically-effective combination of an amount of a the CYP3A4 inhibitor and an amount of ixabepilone to achieve the enhanced pharmacological effect.

Description

USE OF IXABEPILONE IN COMBINATION WITH CYP3A4 INHIBITORS

FOR PHARMACEUTICALS

BACKGROUND OF THE INVENTION

Ixabepilone is a semisynthetic analog of epothilone B. It is [IS- [lR*,3R*(E),7R*,10S*,HR*,12R*,16S*]]-7,l l-Dihydroxy-8, 8,10,12,16- pentamethyl-3 -[ 1 -methyl-2-(2-methyl-4-thiazolyl)ethenyl]-4-aza- 17- oxabicyclo[14.1.0]heptadecane-5,9-dione, having the structure:

Ixabepilone stabilizes microtubules, induces apoptosis, and has demonstrated high anti-tumor activity. Ixabepilone, processes for preparing ixabepilone, and formulations and methods of treatment or Use comprising ixabepilone, are disclosed in U.S. Patent 6,365,749; U.S. Patent 6,518,421; U.S. Patent 6,605,599; U.S. Patent 6,670,384; U.S. Patent 6,686,380; U.S. Patent 6,689,803; U.S. Patent 6,982,276; U.S. Patent 7,008,936; U.S. Patent 7,022,330; and U.S. Patent Application Publication 2003/0073677 Al, each of which is incorporated herein by reference in its entirety.

Ixabepilone is a cytotoxic compound and administration of the compound presents adverse effects of the human patient while treating the cancer. For example, adverse reactions in monotherapy include peripheral sensory neuropathy and fatigue. Combination treatments, which are common in the oncological field, present the potential for further side effects. Uses of ixabepilone are sought that provide efficacious medicaments for treatment at lower administered dosages.

SUMMARY OF THE INVENTION The applicants have surprisingly discovered that use of ixabepilone in combination with inhibitors of CYP3A4/5 enzymes, provides a medicament that has an enhanced beneficial anti-cancer effect as compared with when ixabepilone is administered unaccompanied by ketoconazole at the same dose. In particular, applicants have discovered that use of ixabepilone to treat cancer (and in preparation of a medicament) can be effectively achieved with a dose that is substantially less than the recommended dose for treating cancer when ixabepilone is administered alone. In the inventive Uses herein, the CYP3A4/5 inhibitor, for example, ketoconazole or lapatinib, inhibits the removal of the ixabepilone by the CYP3A4/5 enzymes, thus allowing treatment of cancer using lower amounts of ixabepilone than the treatment using ixabepilone in the absence of ketoconazole or lapatinib. The Use may also be employed to prolong the exposure of the cancer cells to higher levels of ixabepilone, by inhibiting the removal of the ixabepilone by CYP3A4/5 enzymes, when compared to ixabepilone administered in the absence of the CYP3A4/5 inhibitor(s).

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A-1B are tables (Tables 1A-1B) respectively, showing results of a clinical study directed to the interaction of ixabepilone and a CYP3A4/5 inhibitor, namely ketoconazole, and pharmacokinetic parameters for ixabepilone, as follows:

(IA): Summary Statistics for ixabepilone PK parameters. The C_maχ and AUC ₀__∞ values are geometric means (%CV) and the remaining parameters are means (+ SD). The sample size (n) represents number of patients assessed;

(IB): Statistics for ixabepilone dose normalized C_maχ and AUC _{0 ∞}; (1C): Cycle 1 dose-limiting toxicities; and

(ID): Percent of PBMCs with microtubule bundles observed in Cycle 1 and 2 end-of-infusion (* p = 0.29); FIG. 2 illustrates an alternative embodiment showing the maximum percentage of microtubule bundles (MTB) bundling in peripheral blood mononuclear cells where ixabepilone is administered at reduced in combination with ketoconazole (Cycle 1) and where ixabepilone is administered at full dose (Cycle 2);

FIG. 3 A shows concentration-dependent metabolism of ixabepilone in human livermicrosomes;

FIG. 3B shows concentration-dependent metabolism of ixabepilone in human cDNA expressed CYP3A4/5 enzymes; FIG. 3 C shows clinical results of the relationship of percent PBMCs with microtubule bundles and ixabepilone plasmaconcentration.

The figures are illustrative, and non-limiting in nature, and are further described below in the Examples.

DETAILED DESCRIPTION OF THE INVENTION Ixabepilone is a semi-synthetic analog of epothilone B that binds tubulin and induces formation of microtubule bundles in cells which can be measured in the laboratory. Mani S et ah, "The clinical development of new mitoticinhibitors that stabilize the microtubule," Anticancer Drugs 2004; 15(6):553-8. Mani S, et ah, "Phase I clinical and pharmacokinetic studyof BMS-247550, a novel derivative of epothilone B, in solid tumors," Clin. Cancer Res 2004; 10(4): 1289-98. McDaid et al, "Validationof the pharmacodynamics of BMS-247550, an analogue of epothilone B, during a phase I clinical study," Clin. Cancer Res. 2002;8(7):2035-43. Cytochrome P450 enzymes include a number of human cytochrome P450 enzymes, including the CYP3A family of enzymes, i.e., CYP3A4 and CYP3A5. References to "CYP3A4/5" are intended to include either or both of CYP3A4 and CYP3A5. This family of enzymes catalyzes oxidative and reductive reactions and has activity towards a chemically diverse group of substrates. These enzymes are the major catalysts of drug biotransformation reactions and also serve an important detoxification role in the body. Inhibitors of the cytochrome P450 enzymes, particularly, CYP3A4/5 inhibitors, interfere with the body's ability to detoxify. Thus, developing pharmaceuticals for human consumption that inhibit CYP3A4/5, and/or that may effectively and safely be used in combination with compounds that inhibit CYP3A4/5, presents particular challenges. See, for example, the Guidance for Industry: In Vivo Drug Metabolism/Drug Interaction Studies— Study Design, Data Analysis, and Recommendations for Dosing and Labeling prepared by the Food and Drug Administration (November 1999). In research and development of pharmaceuticals, CYP3A4/5 inhibition may be considered an undesirable activity, and efforts are directed in research to develop compound that do not inhibit

CYP3A4/5. See, e.g., US 6,992,193 B2, "Sulfonylamino phenylacetamide derivatives and methods of their use." Commonly-known CYP3A4/5 inhibitors include HIV protease inhibitors (indinavir, nelfmavir, ritonavir), amiodarone, cimetidine, clarithromycin, diltiazen, erythromycin, fluvoxamine, grapefruit juice, itraconazole, ketoconazole, mibefradil, nefazodone, troleandomycin, and verapamil. Lapatinib, an FDA approved tyrosine kinase inhibitor available from Glaxosmith Kline, is also a CYP3A4/5 inhibitor.

Thus, the term CYP3A4/5 inhibitors as used herein include each of these substances, as well as any other CYP3A4/5 inhibitors well known in the field. See, e.g., WO 2005/007631. Potent CYP3A4/5 inhibitors, which are of particular interest in view of their potency, include ketoconazole, itraconazole, ritonavir, amprenavir, indinavir, nelfmavir, delavirdine, and voriconazole.

Ketoconazole, one of the potent CYP3A4/5 inhibitors, is an imidazole compound used as an antifungal agent. Ketoconazole is cis-l-acetyl-4-[4-[[2-(2,4-di- chlorophenyl)-2-( 1 H-imidazol- 1 -ylmethyl)- 1 ,3 -dioxolan-4- yl]methoxy]phenyl]piperazine, and has the structure:

Ketoconazole was originally described in US Pat. 4,335,125, incorporated herein, with its principal utility being as an antifungal agents. Ketoconazole and formulations are well known and widely described, for example, see US Pat.

4,569,935; US 2005/0013834 Al, "Pharmaceutical Formulations Comprising Ketoconazole"; US 2004/0063722Al, "Antifungal Keoconazole Composition for

Topical Use"; Rotstein et al, J. Med Chem. (1992) 35, 2818-2825 (describing stereoisomers of ketoconazole).

Applicant herein has discovered that using CYP3A4/5 inhibitors in combination with ixabepilone provides surprisingly advantageous results, enabling a reduction in the dose of ixabepilone. A clinical study was performed in patients with cancer evaluating the impact of ketoconazole (inhibitor of CYP3A4) on pharmacokinetics, drug-target interactions and pharmacodynamics of ixabepilone.

Based on the clinical study, it was discovered that in patients, ketoconazole co- administration resulted in substantial reduction in dose as the maximum dose, for

2 example, a maximum ixabepilone dose administration of 25 mg/m was discovered

2 when compared to single agent therapy (40 mg/m ). Co-administration of ketoconazole with ixabepilone resulted in a 79% increase in AUC _{0 ∞} and the relationship of microtubule bundle formation in peripheral blood mononuclear cells (MT-PBMC) to plasma ixabepilone concentration was well described by the Hill Equation. MT-PBMC correlated with neutropenia. In vitro studies relating to ixabepilone's metabolism were also performed, and applicant's have discovered ixabepilone is likely metabolized by multiple mechanisms, one of which includes CYP3A4/5 catalysis. Ixabepilone is oxidatively metabolized by enzymes CRP3A4/5 in the human body. Furthermore, the inventor's has discovered there is a direct relationship between ixabepilone pharmacokinetics, neutrophil counts and microtubule bundles in PBMCs. Inhibitors of CYP3A4/5 may be used in the context of ixabepilone dosing with reduced dosage of ixabepilone as compared with monotherapy.

Human microsomal studies demonstrate CYP3A4/5 plays a major role in the oxidative metabolism of ixabepilone at concentrations of 0.1 to 25 μM in native human liver microsomes. The clinical study validates in vitro findings that inhibition of CYP3 A4/5 by ketoconazole significantly increase the exposure to ixabepilone, and that inhibition of its metabolism directly alters its blood exposure. In vitro microsomal studies (described further below) show that ixabepilone is selectively metabolized by CYP3A4/5 and not by other cytochromes tested. The clinical study with ketoconazole and ixabepilone clearly indicate that inhibition of CYP3 A4/5 by ketoconazole significantly increases the exposure of ixabepilone in the blood and alters drug-target effect.

Accordingly, the invention herein is directed to combined use of ixabepilone and CYP3A4/5 inhibitors, particularly lapatinib and ketoconazole, where the ixabepilone is administered at a substantially reduced dose to achieve the same effect that would be obtainable from a higher dose recommended for administration of ixabepilone in the absence of CYP3A4/5 inhibitors. The discoveries and data herein herein support Uses of ixabepilone in combination with other CYP3A4/5 inhibitors, at reduced doses of ixabepilone. Even though ketoconazole is one of the most potent inhibitors of CYP3A4, other clinically important inhibitors of CYP3A4/5 are described above, and are commonly used in cancer patients. See, Marechal, et ah, "In silico and in vitro screening for inhibition of cytochrome P450 CYP3A4 by comedications commonly used by patients with cancer," Drug Metab Dispos

2006;34(4):534-8, incorporated herein. The invention herein contemplates Use of any such CYP3A4/5 inhibitors in the inventive Uses and methods described herein.

Additionally, inhibition of CYP3A4/5 by ketoconazole increases ixabepilone exposure in the blood which directly correlates with increased formation of microtubule bundles in PBMCs. According to one embodiment of the invention, a technically straightforward assay (~ <8hr performance time) is used to visually quantitate tubulin bundles and predict both neutropenia and blood levels of ixabepilone. Applicants have discovered there is a direct relationship between ixabepilone pharmacokinetics, neutrophil counts, and microtubule bundles in PBMCs. Hence, a count of microtubule bundles in PBMCs serve as a validated surrogate for assessing ixabepilone toxicity.

According to yet another embodiment of the invention, the CYP3A4/5 inhibitor is co-administered with ixabepilone, also in co-administration with a compound that is an activator of the human pregnane x receptor. In this embodiment, co-administration of the CYP3A4/5 inhibitor and ixabepilone is advantageous in both protecting against inadvertent metabolism and drug interactions with ixabepilone and aiding in its anti-tumor effects. Co-medications (e.g., dexamethasone) routinely used in cancer patients can serve as potent activators of the human pregnane x receptor (PXR). PXR regulates CYP3A4/5 at the level of transcription, which could alter drug metabolism by inducing its expression. Ketoconazole can inhibit PXR mediated CYP3 A4/5 transcription and normalize transcriptional regulation of CYP3A4/5 across the patient population. Furthermore, PXR can also regulate tumor drug metabolism and resistance and ketoconazole may inhibit this process also. Together, co-administration of ketoconazole may be advantageous. Supporting these findings are the observation that ketoconazole can augment cytotoxicity of drugs (e.g., nocodazole) in cancer cells. DEFINITIONS

The following are definitions of various terms used herein to describe the present invention.

The term "ixabepilone" or "ixa" encompasses the aza-epothilone B analog ixabepilone, as described above on page 1, or a pharmaceutically-acceptable solvate, clathrate, hydrate, and/or prodrugs thereof (including mixtures of any of the foregoing). Processes for making ixabepilone are described in the art, for example, US Pat. 6,365,749, U.S. Pat. 6,518,421, and US patent application publication 2004/0132146Al (Serial No. 10/668,032), all of which are assigned to the present assignee and incorporated herein by reference.

The term "prodrug", as used herein, denotes a compound which, upon administration to a subject undergoes chemical conversion by metabolic or chemical processes to yield the active ingredient, i.e., ixabepilone.

The term "solvate", as used herein, refers to a form of compound that further comprises a solvent, such as for example, an alcohol such as ethanol.

The term "clathrate", as used herein, refers to a form having a crystalline structure with voids or channels that may optionally comprise solvent or water.

The term "hydrate", as used herein, refers to a form of ixabepilone that further comprises water. "Substantially reduced dose" or a "substantial reduction in dose" means a reduction in dose, i.e., for ixabepilone, that is at least twenty-five percent less than the standard recommended dose, more preferably at least thirty -percent less, and most more preferably more than 40% less, and most preferably about 40-50% less. The "standard recommended dose" or "standard dose" for ixabepilone is 40 mg/m administered intraveneously over three hours every three weeks.

With reference to certain abbreviations, AUC is the area under the curve; MRT is the mean residence time; Vss is the volume of distribution at steady state; MTD is maximum tolerated dose; DLT is dose limiting toxicity; SEM is standard error of the mean; and PET is a form of well known scan, i.e., position emission tomography. ALTERNATE EMBODIMENTS OF THE INVENTION

A method is disclosed for the treatment of cancer comprising administering to a human a therapeutically-effective combination of CYP3A4/5 inhibitors (e.g., lapatinib, ketoconazole) and ixabepilone. Also disclosed are Uses for preparing medicaments for treatment of human patients, comprising a combination of

CYP3A4/5 inhibitors (e.g., lapatinib, ketoconazole) and ixabepilone. The CYP3A4/5 inhibitors (e.g., lapatinib, ketoconazole) can be administered daily. In one embodiment, the CYP3A4/5 inhibitor(s) (e.g., lapatinib, ketoconazole) is administered before the ixabepilone administration, for example, starting at least one day prior to the administration of the ixabepilone. In one embodiment, the

CYP3A4/5 inhibitors (e.g., lapatinib, ketoconazole) is administered daily starting at least one day prior to the ixabepilone administration, and is continued with daily administration during the administration of the ixabepilone. The administration of the CYP3A4/5 inhibitors (e.g., lapatinib, ketoconazole) can be continued for one or more days after completion of the ixabepilone administration. The cycle of CYP3A4/5 inhibitors (e.g., lapatinib, ketoconazole) and ixabepilone administration can be repeated one or more times, as appropriate to treat the patient.

The suitable amount of ixabepilone (i.e., reduced dose) to be administered according to the invention includes at least about 15 mg/m², and preferably, at least about 20-25 mg/m². Examples of suitable ranges for Use in the invention include from about 10 to about 35 mg/m², more preferably from about 15 to about 30 mg/m², and most preferably at from about 20 to about 30 mg/m². Examples of particular doses include about 20 mg/m², about 25 mg/m², and about 30 mg/m². The ixabepilone may be administered on different cycles and over different time spans but in one embodiment is administered over a period of 1 to 3 hours, once every 21 days. Also contemplated is oral administration of ixabepilone, for example, in the form of an enteric coated bead used to prepare a tablet or capsule, as described in WO 2006/055740, published May 26, 2006, incorporated herein.

In the case of ketoconazole, suitable ranges to be administered include at least about 100 mg per day, at least about 200 mg per day, and at least about 300 mg per day. Examples of suitable ranges include from about 100 to 400 mg per day, about 200 to about 400 mg per day, and about 300 to about 400 mg per day. Ketoconazole administration may be once daily, or divided into two or more dosages given over a 24 hour period.

In one embodiment, a method of treating cancer in a human is provided comprising administering to the human a therapeutically-effective combination of (1) an amount of a CYP3A4/5 inhibitor (e.g., lapatinib, ketoconazole) and (2) at least about 15-30 mg/m of ixabepilone wherein the ixabepilone is administered intravenously every three weeks, preferably over the course of a 3 hour infusion. Preferably, about 20-25 mg/m² of ixabepilone is administered intravenously every three weeks, preferably over the course of a 3 hour infusion. In one embodiment, the Use or method of treatment involves about 20 mg/m² In another embodiment, the Use or method of treatment involves about 25 mg/m .

In a different embodiment, a method of treating cancer in a human is provided comprising administering to the human a therapeutically-effective combination of (1) at least about 100 mg per day of ketoconazole and (2) at least about 15 mg/m² of ixabepilone. Alternate variations of this embodiment include administration of about 200 mg per day ketoconazole, as well as about 300 mg per day, and also about 400 mg per day, of ketoconazole. In these embodiments, at least about 20-25 mg/m² of ixabepilone is administered intravenously every three weeks. Another embodiment encompasses the administration of at least about 300 mg per day of ketoconazole and at least about 20-25 mg/m² of ixabepilone.

In a different embodiment, a method of treating cancer in a human is provided, comprising administering to the human a therapeutically-effective combination of (1) an amount of a CYP3A4/5 inhibitor (e.g., lapatinib, ketoconazole) and (2) an amount of ixabepilone, wherein the combined administration provides an enhanced anti-cancer effect as compared with when ixabepilone is administered unaccompanied by a CYP3A4/5 inhibitor (e.g., lapatinib, ketoconazole). By "enhanced anticancer effect," it is meant that the dose of ixabepilone can be substantially reduced, wherein the term substantially reduced is as defined above, and includes reduction in dose of at least about 25%, and also up to about 40-50%, while achieving the same microtubule stabilizing effect, e.g., when the CYP3A4/5 inhibitor (e.g., lapatinib, ketoconazole) is administered in combination with the ixabepilone, the dose of ixabepilone can be reduced while achieving the same microtubule stabilizing effect and thus, the same anti-cancer effect.

UTILITY Ixabepilone is useful as a microtubule-stabilizing agent. Ixabepilone is useful in the treatment of a variety of cancers and other proliferative diseases including, but not limited to, the following:

- carcinoma, including that of the bladder, breast, colon, kidney, liver, lung, ovary, pancreas, stomach, cervix, thyroid, and skin, including squamous cell carcinoma;

- hematopoietic tumors of lymphoid lineage, including leukemia, acute lymphocytic leukemia, acute lymphoblastic leukemia, lymphomas including B-cell lymphoma, T-cell lymphoma, Hodgkins lymphoma, non-Hodgkins lymphoma, hairy cell lymphoma, and Burketts lymphoma; - hematopoietic tumors of myeloid lineage, including acute and chronic myelogenous leukemias and promyelocytic leukemia;

- other tumors, including melanoma, seminoma, teratocarcinoma, neuroblastoma, and glioma;

- tumors of the central and peripheral nervous system, including astrocytoma, neuroblastoma, glioma, and schwannomas;

- tumors of mesenchymal origin, including fibrosarcoma, rhabdomyoscaroma, and osteosarcoma; and

- other tumors, including melanoma, xeroderma pigmentosum, keratoacanthoma, seminoma, thyroid follicular cancer, and teratocarcinoma.

Ixabepilone is useful for treating patients who have been previously treated for cancer, as well as those who have not previously been treated for cancer. The methods and compositions of this invention can be used in first-line and second-line cancer treatments and in the adjuvant setting. Furthermore, the methods of the invention can be applied for treating refractory or resistant cancers.

Ixabepilone will induce or inhibit apoptosis, a physiological cell death process critical for normal development and homeostasis. Alterations of apoptotic pathways contribute to the pathogenesis of a variety of human diseases. The subject compounds, as modulators of apoptosis, will be useful in the treatment of a variety of human diseases with aberrations in apoptosis including, but not limited to, cancer and precancerous lesions, immune response related diseases, viral infections, kidney disease, and degenerative diseases of the musculoskeletal system.

The recommended dosage of ixabepilone in the absence of the CYP3A4/5 inhibitor(s) is 40 mg/m administered intravenously over 3 hours every 3 weeks. Body surface area may be considered as a factor in determining the recommended dose for a particular patient. Doses for patients with BSA (body surface area) greater

2 2 than 2.2 m can be calculated based on 2.2 m . Additionally, dose adjustments may be made, or treatment delayed or discontinued, if toxicities are present. Additionally, dose reduction is recommended when administering ixabepilone for monotherapy to patients with hepatic impairment. Based upon a population pharmacokinetic analysis in human patients, gender, race and age do not have meaningful effects on the phamacokinetics of ixabepilone.

Ixabepilone may be administered parenterally as described in U.S. Patent 7,022,330, U.S. Patent 6,670,384, U.S. Patent Application Publication 2005/0171167 Al, WO 2005/110407, and PCT/US2006/011920, each of which is incorporated herein by reference in its entirety. Ixabepilone may be administered orally as described in U.S. Patent 6,576,651 and U.S. Patent Application 11/281,855, each of which is incorporated herein by reference in its entirety. Ixabepilone may be administered in combination with other agents, such as those described in US 2003/0073677, including capecitabine (Xeloda™), cetuximab (Erbitux™), trastuzumab (Herceptin™), and/or bevacizumab (Avastin™). The co-administration of ixabepilone and CYP3A4/5 inhibitor(s) described herein also contemplates use of one or more of these additional anti -cancer agents.

Ixabepilone can be prepared for intraveneous administration and/or oral administration by methods known in the field. One approach to formulate ixabepilone for pharmaceutical use involves preparing a lyophilized product which then can be packaged and transported in a solid state. With this formulation, the lyophilized product may be reconstituted with a vehicle and then further diluted with an infusion fluid prior to administration to the patient. U.S. Patent No. 6,670,384 discloses a process for obtaining a lyophilized product using a tertiary butanohwater mixture, which then can be packaged and transported in a freeze-dried solid state. With this product, the intravenous formulation is typically prepared by medical professionals at the site of administration before the start of the infusion. The constitution vehicle may comprise a mixture of Dehydrated Alcohol (e.g., ethanol) and a nonionic surfactant, such as a polyoxyethylated castor oil (e.g., Cremophor^®). A mixture of a nonionic surfactant (e.g., Cremophor^R) and ethanol is typically used to constitute the lyophilized ixabepilone. Cremophor^® may be used for solubility reasons, e.g., in view of ixabepilone's relatively low water solubility. The reconstituted ixabepilone solution may then diluted with an infusion fluid and administered via IV administration. US patent application Serial No. 10/055,653, filed January 23, 2002 (assigned to the present assignee), states that because of its relatively narrow pH range, Lactated Ringer's Injection (LRI) is a preferred diluent for ixabepilone. LRI has a pH range of about 6.0 to 7.5. (Per 100 mL, Lactated Ringer's Injection contains Sodium Chloride USP 0.6 g, Sodium Lactate 0.31 g, Potassium chloride USP 0.03 g and Calcium Chloride-2H₂O USP 0.02g. The osmolarity is 275 mOsmol/L, which is close to isotonicity.) Ixabepilone is provided as a two-vial system, with the lyophilized drug in one vial, and a vehicle for reconstitution in a second vial; instructions are provided when the drug is supplied for reconstituting the ixabepilone and administering it to a human patient.

An alternative formulation that involves use of saline or dextrose was developed and is described in US patent application Serial No. 10/979,958, filed November 3, 2004 (assigned to the present assignee). In the formulation of the '958 patent application, ixabepilone is constituted with a solution vehicle, wherein the solution vehicle includes (in addition to solvent) at least one buffer and at least one pH adjusting ingredient, e.g., a base. The constituted solution may be diluted with an infusion fluid to provide a formulation for administration.

Other formulations involving ixabepilone are described in the art. For example, US patent application Serial No. 60/572,279, filed May 18, 2004, describes a nanoparticulate formulation for ixabepilone, and WO 2006/055740, filed November 18, 2004, describes an enteric-coated bead formulation for ixabepilone. (Both of these applications are assigned to the present assignee and incorporated herein by reference.) These formulations provide many advantages.

EXAMPLES The following examples are provided, without any intended limitation, to further illustrate the present invention.

EXAMPLE 1 Clinical Ketaconazole-Ixabepilone Interaction Study A clinical study was conducted to evaluate the effects of co-administration of ixabepilone and potent CYP3A4/5 inhibitor(s), i.e., ketoconazole, as compared with when ixabepilone is administered in the absence of the CYP3A4/5 inhibitor(s).

Patient Eligibility Advanced cancer patients unresponsive to standard therapeutic interventions were enrolled in this open label phase I study. Additional criteria included an ECOG performance score of 0-1 and no more than three prior chemotherapeutic regimens. The remaining criteria were identical to previously published reports (See, e.g., Mani S, Macapinlac M, Jr., Goel S, et al. The clinical development of new mitoticinhibitors that stabilize the microtubule. Anticancer Drugs 2004;15(6):553-8; Mani S, McDaid H, Hamilton A, et al. Phase I clinical and pharmacokinetic studyof BMS-247550, a novel derivative of epothilone B, in solid tumors. Clin Cancer Res2004; 10(4): 1289- 98; Zhuang SH, Agrawal M, Edgerly M, et al. A Phase I clinical trial of ixabepilone(BMS-247550), an epothilone B analog, administered intravenously on a daily schedulefor 3 days. Cancer 2005;103(9): 1932-8.

Study Design, Treatment Administration and Dose Escalation

This was an open-label sequential study administering ketoconazole, a nanomolar inhibitor of cytochrome P450 3 A4, with ixabepilone. In cycle 1 (3 weekly), ixabepilone was co-administered in escalating doses per treatment cohort with a fixed dose of ketoconazole. In cycle 2, ixabepilone was administered as a fixed

2 dose (40 mg/m ) without administering ketoconazole. During cycle 1, patients received a 3 -hour intravenous (IV) infusion of

2 ixabepilone on day 1 at a starting dose of 10 mg/m . Ketoconazole (400 mg/d) was given orally with a meal on day -1 (24 hours before the infusion of ixabepilone), on day 1 (2 hours prior to the infusion of ixabepilone) and on days 2 to 5 (six doses). The

2 dose of ixabepilone in cycle 1 was to be increased to 20, 30, and 40 mg/m for subsequent cohorts of subjects based on safety evaluations. However, the dose

2 escalation increment could be less than 10 mg/m based on observed events in the preceding dose level and the pharmacokinetic and pharmacodynamic data obtained at prior dose levels. Based on a standard minimum enrollment design of 3 subjects at each dose level, any dose level could be expanded to at least six patients based on the observation of one or more dose-limiting toxicities. The maximum tolerated dose (MTD) was exceeded when defined by the dose at which at least 33% of six patients had dose-limiting toxicity(ies). One dose level below this, the MTD was fully explored in terms of toxicities observed in at least 6 patients. For each dose level at the MTD or below, additional subjects could be enrolled to obtain additional safety data.

During cycle 2, based on cycle 1 toxicities, patients received a 3 -hour IV

2 infusion maximum of 40 mg/m of ixabepilone on day 1. The toxicity based dose reductions and dose-limiting toxicity (DLT) criteria for ixabepilone were followed as published in prior studies. Similarly, prophylaxis regimens for ixabepilone were strictly adhered to as previously published. See Mani S, McDaid H, Hamilton A, et al. Phase I clinical and pharmacokinetic study of BMS-247550, a novel derivative of epothilone B, in solid tumors. Clin Cancer Res2004; 10(4): 1289-98; Mani S, McDaid HM, Grossman A, et al. Peripheral blood mononuclear andtumor cell pharmacodynamics of the novel epothilone B analogue, ixabepilone. Ann Oncol 2006. Pre- and Post-Treatment Investigations

Standard physical, objective anti-tumor response assessments and laboratory

14 assessments were carried out. In addition to standard protocol tests, the C- erythromycin breath test (EBMT) was administered prior to protocol treatment to assess for hepatic CYP3A activity (see www.metsol.com; Metsol, Nashua, NH).

Toxicity Assessment

Since toxicity was the major endpoint of this clinical study, clinical and laboratory assessments were performed weekly. In certain patients, especially those with abnormal laboratory parameters, repeat laboratory assessments were performed twice within the same week and continued as clinically indicated.

Pharmacokinetic (PK) and Pharmacodynamic (PD) Samples

Blood samples (4 ml per sample) were collected from an indwelling catheter or by direct venipuncture using tubes containing K₃EDTA as the anticoagulant. Every reasonable attempt was made to obtain a dedicated peripheral catheter on the opposite arm or side of body from that used for drug infusion. For the purposes of assessing ixabepilone blood concentrations, the collection times were predose, at 90 and 180 minutes from start of dosing, then at 0.25, 0.5, 1.0, 3.0, 5.0, 22, 45, 69, 93 and 117 hours from the end of infusion. Within one hour of collection, for each blood sample, plasma was collected by centrifugation (10 minutes at 1000 x g at 4°C) and stored at - 20⁰C till analysis.

Bioanalytical Methods Human EDTA plasma samples were analyzed for ixabepilone using

LC/MS/MS method as previously validated and described for clinical use (See Mani publications, above). The standard curves were well fitted by a 1/x-weighted quadratic equation over the concentration range of 2.00 to 500 ng/mL. Statistical Analysis

To assess the effect of ketoconazole on the PK of ixabepilone, two-way analyses of variance was performed on dose-normalized log(C_maχ) and log(AUC₀ __∞) for all patients who had values for Cycle 1 and Cycle 2. The factors in the analysis

2 were patient and cycle. Since a 40 mg/m MTD from Cycle 1 was not achieved, C_maχ

2 and AUC_{0 ∞} from Cycle 1 were dose normalized to a 40 mg/m dose. Point estimates and 90% confidence intervals for means and differences between means on the log scale were exponentially factored to obtain estimates for geometric means and ratios of geometric means on the original scale. The ratio of population geometric means of C_maχ and AUC_{0 ∞} for ixabepilone given in combination with ketoconazole (Cycle 1) to ixabepilone given alone (Cycle 2), along with respective 90% confidence intervals, was determined.

Results: Clinical Ketoconazole Interaction Study Demographics and Treatment Compliance. Twenty-nine patients were enrolled into this study. Of the 29 patients, 2 (7%) were never treated. The median age of enrollment was 62 years (range, 33-84) and 18 patients (67%) were female. Overall, ECOG performance score was 0 (n=l) and 1 (n=26). Twenty-four patients (89%) had extensive (metastatic) disease and 26 (96%) had undergone chemotherapy previously.

The number of chemotherapy regimens used were two and three in 10 (37%) and 13 (48%) patients, respectively. The most common diagnosis was gynecologic malignancy (carcinoma of ovaries, cervix, endometrium) followed by prostatic adenocarcinoma. Liver metastases was observed in 2 patients (~7%) and the median (range) pretreatment bilirubin (mg/dl), SGPT (IU/L) and albumin (g/dl) levels were 22 (14-43), 19 (8-60), 3.8 (2.8-4.3). The main reason for discontinuation of treatment was disease progression/relapse (12 patients, 44%).

The erythromycin breath test, a measure of hepatic CYP3 A activity, was administered to subjects prior to treatment for exploratory evaluation as a marker of

14 the rate of clearance of ixabepilone. The percent of C metabolized per hour ranged from 0.96 to 4.72, a 4.9-fold range. DNA from 24 subjects were analyzed for genotype of CYP3A5 and CYP2D6. Nine subjects and 3 subjects had 1 or 2 CYP3A5 alleles that coded for active enzyme, respectively, based on a lack of either the *3 or *6 variant. Seven subjects were homozygous wild type for CYP2D6. All patients received ketoconzole administered by study personnel on-site and after administration of ketoconazole, a mouth check was performed to ensure that the subject had swallowed the dose. A total of 2 patients (7%) missed at least one day of ketoconazole dosing in cycle 1. In addition, treatment compliance was monitored by drug accountability, medical record and case report forms. In terms of concomitant medicines, there were no xenobiotics used that were known to interfere with CYP3A4/5 or -3A5 directed metabolism.

Pharmacokinetics and Interaction Effect Analysis

The exposure and clearance of ixabepilone is affected by co-administration of ketoconazole (See Figures IA- IB, Tables IA and B). Specifically, ixabepilone clearance decreased in 19 of 22 patients when co-administered with ketoconazole. As shown in Figure IB (Table IB), co-administration of ketoconazole with ixabepilone resulted in an increase of approximately 7% in ixabepilone C_maχ. However, the 90% confidence interval indicates that this effect is not statistically different from no change. Co-administration of ketoconazole with ixabepilone resulted in a 79% increase in AUC _{0 ∞}. The 90% confidence interval indicates that this effect is statistically different from no change.

Drug Target Effect Analysis The formation of microtubule bundles caused by ixabepilone in PBMCs is a plasma concentration-dependent effect. For cycle 1 (ixabepilone and ketoconazole) and Cycle 2 (ixabepilone alone), the percent of PBMCs with tubulin bundles was greatest just prior to the end of infusion at 3 hours, remained above baseline at 6 and 24 hours and returned to ~ baseline at 48 hours. The %PBMCs with microtubule bundles also increased with presence of ketoconazole (Figure ID, Table ID). At 25

2 mg/m (n=6) of ixabepilone, the % (SEM) bundle formation was 38.7(+ 6.2) 2 compared to that at 40 mg/m (n=17) of ixabepilone in the absence of ketoconazole (40.7 + 8.6%). The relationship of tubulin bundle formation to plasma ixabepilone concentration after ixabepilone alone was well described by the Hill Equation with effect at zero concentration (E₀) fixed to zero. The fitted parameter values for the model are presented in Figure 3C. The Hill equation with E₀ fixed at zero was the best model compared to the Hill equation with E₀ as a model parameter, the Emax model with E₀ fixed to zero, the Emax model with E₀ as a model parameter, the linear model or the log-linear model, based on Objective function, Akaike criteria and Schwartz criteria. The plot relationship of tubulin bundle formation to plasma ixabepilone

2 concentration (for patients dosed at 40 mg/m only) is shown in Figure 3 C. The percent baseline tubulin bundles in cycle 1 was 0.8% which was nearly identical to that observed in baseline values from a previous study (n=49) and for baseline values in cycle 2 in this study, reflecting that ketoconazole itself had no influence on tubulin bundle formation in PBMCs. In addition, ixabepilone mediated tubulin bundle formation is not inhibited by ketoconazole in HepG2 cells.

Based on these findings, parameter estimates using all the data from cycle 1 and 2 together demonstrated that the best model remained the Hill equation with E₀ fixed at zero. The parameter estimates were similar to that described above -Emax (%) was 46.4%, EC₅₀ (ng/ml) 35.2 and sigmoidicity factor was 1.18. These data show that ketoconazole increases ixabepilone mediated tubulin bundles in PBMCs by increasing the concentration of ixabepilone.

Clinical Adverse Events

Table 1C lists the cycle 1 dose-limiting toxic events following administration of ixabepilone and ketoconazole. During the administration of ketoconazole dose alone, there were no grade 2 or greater toxic events observed. Most patients complained of grade 1 abdominal discomfort (bloating/nausea) for the duration of this treatment period. The initial dose level of ixabepilone administered for cycle 1 was 10

2 2 mg/m and subsequent cohorts of 20 and 30 mg/m were opened. Based on observed

2 DLTs and available pharmacokinetic and pharmacodynamic data, the 30 mg/m 2 cohort was closed and the 20 mg/m cohort was expanded to 6 patients. On further

2 2 safety data obtained at 20 mg/m , an intermediate dose level of 25 mg/m was opened.

2 2

Since 2 of 4 (50%) patients at 30 mg/m had DLTs, and 2 of 7 (29%) at 25 mg/m had DLTs, the latter dose was defined as the MTD by protocol criteria. The overall treatment-related adverse event profile of ixabepilone administered concomitantly with ketoconazole in cycle 1 was similar to that of ixabepilone administered alone beyond cycle 1. The most common treatment-related adverse events in cycle 1 across all dose cohorts were fatigue (n=19 patients, 70%) and nausea (n=13, 48%). The most common treatment-related events beyond cycle 1 were fatigue (n=17 patients, 74%) and nausea (n=12, 52%).

Peripheral neuropathy is a dose-limiting side effect after chronic dosing with ixabepilone. Peripheral neuropathy was primarily sensory and grade 1 (n=6, 22%) or grade 2 (n=7, 26%). Overall, only 2 patients (7%) reported grade 3 neuropathy and there were no study drug discontinuations due to peripheral neuropathy.

Antitumor Response

Twenty-three patients (85%) had at least one target tumor lesion for assessment. Four patients (15%) had no measurable or evaluable target tumor lesions. Investigator assessment of tumor response indicated that 1 patient (4%) had a complete response (ovarian adenocarcinoma with abdominal metastases) based on serial PET scans, 12 (44%) had stable disease, 10 (37%) had progressive disease and response status was undetermined in 4 (15%) patients.

EXAMPLE 2 Alternative Embodiment

Figure 2 reflects results of an alternate embodiment. The graph represents the percentage of MTB bundling in PBMCs in two cycles of treatment - one cycle, with 8 patients, involving co-administration of ixabepilone at substantially reduced dose (50% of dose recommended for monotherapy) and ketoconazole (Cycle 1), and a second cycle with 17 patients involving monotherapy at the standard recommended dose. As can be seen in Figure 2, the anti-cancer effect achievable with ixa at reduced dose and ketoconazole in combination s substantially the same as that achieved with ixabepilone at full dose.

EXAMPLE 3 In Vitro Studies

In order to determine the effect of cytochrome P450s on ixabepilone biotransformation in vitro, a series of studies with liver microsomes were performed.

Enzyme Kinetics

14 Under linear conditions, C-ixabepilone was incubated with pooled human liver microsomes (n= 20) (at drug concentrations of 0.1, 0.3, 1, 2.5, 5, 10, and 25 μM) and CYP3A4 (at drug concentrations of 0.1, 0.3, 1, 2.5, 5, 10, 25, 50, and 100 μM) in the presence of NADPH in triplicate. Incubations (0.5 mL) in 0.1 mM phosphate buffer containing 0.5 mM Of MgCl₂ (pH 7.4) were carried out at 37°C for 5 or 10 min and stopped with ice-cold acetonitrile (1 : 1, v/v). The protein concentration of human liver microsomes was 0.24 mg/ml (for 0.1 and 0.3 μM ixabepilone concentrations) or 0.5 mg/mL (for 1-25 μM ixabepilone concentrations). The CYP3A4 concentration was 25 pmole/mL (for 0.1 and 0.3 μM ixabepilone concentrations) and 50 pmole/mL (for 1-100 μM ixabepilone concentrations). The incubation time was 5 min for incubations at 0.1-2.5 μM ixabepilone concentrations and 10 min for 5-100 μM ixabepilone concentrations. After quenching with acetonitrile (0.5 mL), the samples were centrifuged for 5 min at 3000 rpm. Aliquots (150 μL) from the supernatants were treated with 150 μL of acetonitrile containing 0.5 μM of the internal standard, followed by vortex mixing for 2 min. The supernatants were then separated from the precipitated proteins after a 10-min centrifugation at 3000 rpm and analyzed by LC/MS against a standard curve to determine the concentration of ixabepilone.

K_m and V_maχ values for ixabepilone metabolism in human liver microsomes and CYP3A4 were determined by fitting the parent drug disappearance rates in incubations with ixabepilone at selected concentrations vs. ixabepilone concentrations to the Michaelis-Menten equation [V=(Vmax*S)/(Km+S)] using a nonlinear regression analysis in Sigmaplot. Metabolite Identification

14

Metabolites were identified by analyzing C-ixabepilone (20 μM) incubation of samples from pooled human liver microsomes using LC -MS/MS. The results from these analyses demonstrated that ixabepilone was mainly metabolized to oxidative metabolites. In addition to parent drug ixabepilone, the identified metabolites

14 included P+16, P+14 and P -2 metabolites. Comezoglu, et al. "Metabolism of C- Ixabepilone in mouse,rat, dog, monkey and human liver microsomes, " Drug Metabolism Reviews 2006;38(suppl 2): 173.

cDNA-Expressed CYP Enzymes

Human cDNA-expressed enzymes (CYP1A2, 2A6, 2C8, 2C9, 2C19, 2D6 and 3A4) were incubated with ixabepilone. The incubation mixtures consisted of 100 pmole/mL of CYP enzymes, 0.5 μM of ixabepilone, 1 mM NADPH, and 0.1 M phosphate buffer containing 0.5 mM Of MgCl₂, pH 7.4 in duplicate. The final volumes of the incubation mixtures were 0.5 mL. After 10 min of incubation at 37°C in a water shaker bath, 0.5 mL of ice cold acetonitrile was added to each tube to stop the reaction.

The samples were centrifuged for 5 min at 3000 rpm. Aliquots (150 μL) from the supernatants were mixed with 150 μL of acetonitrile containing 0.5 μM of the internal standard, followed by vortex mixing for 2 min. The supernatants were then separated from the precipitated proteins after a 10-min centrifugation at 3000 rpm and analyzed by LC/MS analysis against a standard curve to determine the concentration of ixabepilone.

Chemical Inhibition

CYP inhibitors and antibodies were incubated with human liver microsomes and ixabepilone (0.5 μM) in triplicate. Human liver microsomes were incubated with 0.5 μM of ixabepilone in the presence of the respective CYP inhibitors, furafylline (CYP1A2, 10 μM), tranylcypromine (CYP2A6, 2 μM), sulfaphenazole (CYP2C9, 10 μM), benzylnirvanol (CYP2C19, 1 μM), quinidine (CYP2D6, 1 μM), ketoconazole (CYP3A4, 1 μM), and montelukast (CYP2C8, 3 μM). Each 0.5 mL incubation mixture contained 430 μL of 0.1 M phosphate buffer (containing 0.5 mM Of MgCl₂; pH 7.4), 50 μL of 10 mM NADPH solution, 2.5 μL of selective chemical inhibitor solution, 5 μL of 0.05 mM ixabepilone solution, and 12.5 μL of human liver microsomes (20 mg/mL). The metabolism-dependent inhibitor of CYPl A2, furafylline, was pre-incubated with human liver microsomes in the presence of NADPH for 15 min in a shaking water bath before ixabepilone was added. After substrate addition, the samples were then incubated for 10 min at 37°C. At the end of the incubation period, 0.5 mL of acetonitrile was added to each incubation mixture to stop the reaction. The samples were centrifuged for 10 min at 3000 rpm. Aliquots (150 μL) from the supernatants were mixed with 150 μL of acetonitrile containing 0.5 μM of the internal standard, followed by vortex mixing for 2 min. The supernatants were then separated from the precipitated proteins after a 10-min centrifugation at 3000 rpm and analyzed by LC/MS against a standard curve to determine the concentration of ixabepilone.

Immunoinhibition

Monoclonal anti-human CYP antibodies (anti-lA2, anti-2C8, anti-2C9, anti- 2Cl 9, anti-2D6, and anti-3A4) were from NIH, Bethesda, Maryland (19). A mixture containing human liver microsomes, 0.1 M potassium phosphate buffer (containing 0.5 mM of MgCl₂), pH 7.4 and monoclonal anti-CYP antibody (anti-CYPlA2, anti-

2C8, anti-2C9, anti-2C19 anti-2D6, or anti-3A4/5) was pre-incubated for 10 min at 37 ⁰C. Then, NADPH and ixabepilone solutions were added to the incubation mixture. The final incubation mixtures consisted of 0.5 mg/mL human liver microsomes (preincubated with monoclonal antibody), 0.5 μM of ixabepilone, 1 mM NADPH, and 0.1 M phosphate buffer, pH 7.4 and incubated for 10 min at 37°C while shaking. The reaction was stopped by addition of 0.5 mL of acetonitrile to each incubation tube. The samples were centrifuged for 10 min at 3000 rpm. Aliquots (150 μL) from the supernatants were mixed with 150 μL of acetonitrile containing 0.5 μM of the internal standard, followed by vortex mixing for 2 min. The supernatants were then separated from the precipitated proteins after a 10-min centrifugation at 3900 rpm and analyzed by LC/MS against a standard curve to determine the concentration of ixabepilone. Positive control incubation was carried out without any antibody solution as described above. An incubation without NADPH and without antibody solution served as a negative control sample. In addition, another control incubation was carried out in the same manner described above but the incubation mixture contained anti-egg white protein antibody to assess for nonspecific reactions.

Assessment of Tubulin in HepG2 Cells in the Presence or Absence of Drug(s)

Immunoflourescence studies with ixabepilone in the presence or absence of drug(s) were performed in cell culture to assess the impact of ketoconazole on the formation of microtubule bundles in cultured cells

In Vitro Results

The consumption of ixabepilone in human liver microsomes and in human cDNA expressed CYP enzymes can be characterized by monophasic Michaelis- Menten kinetics. The K_m values for the oxidative metabolism of ixabepilone were 8.2 and 4.3 μM in human liver microsomes and CYP3A4, respectively. V values were 1399 nmol/mg protein/min (approximately 13 nmol/pmol CYP3A4 in human liver microsome /min) and 17.9 nmol/pmol CYP/min for human liver microsomes and CYP3A4, respectively (Figures 3A and B).

Beyond its two degradants (a diol and an oxazine derivative), several P+16, P+14 and P-2 metabolites for ixabepilone have been characterized. Comezoglu SN,

14

Ly VT, Everett D, et al. Metabolism of C-Ixabepilone in mouse,rat, dog, monkey and human liver microsomes. Drug Metabolism Reviews2006;38(suppl 2): 173. Using cDNA-expressed CYP enzymes, ixabepilone was consumed in appreciable amounts (>90%) only by CYP3A4. When ixabepilone was incubated with human liver microsomes at a concentration of 0.5 μM, 64.5% of ixabepilone was consumed under these conditions. When ixabepilone was incubated in human liver microsomes in the presence of ketoconazole (1 μM), an inhibitor of CYP3A4, the oxidative metabolism of ixabepilone was inhibited by approximately 90%. However, the inhibitors for other CYP enzymes (furafylline for CYP 1A2, tranylcypromine for CYP2A6, montelukast for CYP2C8, sulfaphenazole for CYP2C9, benzylnirvanol for CYP2C19 and quinidine for CYP2D6) did not significantly inhibit the oxidative metabolism of ixabepilone (inhibiton in the range of 5-29%).

Consumption of ixabepilone in human liver microsomes was almost entirely inhibited by anti-CYP3A4 monoclonal antibodies (83%). No inhibition was observed in the presence of other CYP antibodies (anti- 1A2, 2C8, 2C9, 2Cl 9 and 2D6).

Assessment of Tubulin in HepG2 Cells in the Presence or Absence of Drug(s)

Ketoconazole (25 μM) alone has no effect on formation of microtubule bundles. In the presence of ixabepilone (5 μM), ketoconazole (25 μM) did not inhibit tubulin bundle formation in HepG2 cells.

EXAMPLE 4 Clinical Study with Lapatinib

A clinical study is performed where ixabepilone is administered as a 3 hour iv infusion on day 1 of a 21 day cycle. Lapatinib is administered oral, continuously, every day (at least one hour before or one hour after a meal), starting on day 1. For an arm of the study, capecitabine also is administered oral, BID (with food or within 30 minutes after food), on days 1 through 14 of a 21-day cycle. For each of the 2 combinations the MTD level will be expanded to provide additional safety data. Since both lapatinib and ixabepilone are CYP3A4 substrates, stepwise alternative increase of both drugs is implemented to exclude serious combined-treatment toxicity. In the triple combination arm, capecitabine may be escalated

A dose-escalation sequence proceeds as follows:

At least 3 and up to 6 subjects are treated at each dose level and observed for a minimum of 14 days before accrual to the next dose level starts. Dose level -1 is provided in case the MTD is exceeded at dose level 1 or for subjects requiring dose reduction on an individual basis. Once the MTD is identified, that dose level may be expanded. For the doublet combination if MTD is not reached by dose level 3, an additional dose level with lapatinib 1500 mg and ixabepilone 40 mg/m² may be considered.

Data is collected following the same or similar approach as described above for previous clinical studies. Collection of blood samples for PK analysis samples are conducted for all subject participating in the study. For all subjects enrolled in this study, tumor tissue from a prior surgical procedure is submitted. Use of ixabepilone in combination with lapatinib in this study provides an enhanced anti-cancer effect, so that a reduced dose, preferably a substantially reduced dose, of ixabepilone may be administered to achieve the same anti-cancer effect as when ixabepilone is administered at a standard recommended dose and in the absence of the lapatinib. For example, when lapatinib is co-administered, a reduced dose of about 25-32 mg/m² of ixabepilone is effective. EXAMPLE 5 Co administration with Other Epothilones and Analogs in Development

The inventor herein contemplates use of the instant invention as applied to epothilones and epothilone analogs in development that are metabolized in human patients by the CYP3A4/5 enzymes. For example, such other epothilones and analogs may include epothilone B (patupilone), ZK-EPO, and epothilone D analogs, including compounds shown below:

Such other epothilones and compounds may also include compounds as disclosed in US Pat. 6,242,469 and 6,284,781; EP 091227; WO 03/022844; US2004/0053910; US 2004/0152708; US Serial No. 11/214,988; US Pat. 6,605,726; US 2003/0144523 (No. 09/485292); and Klar et al, Angew Chem. Int. Ed. 2006, 45: 1-7, incorporated herein.

Accordingly, applicant contemplates use of the invention herein with ixabepilone, as described above, and with epothilone compounds having the formula,

wherein G is benzothiazol

yl substituted with methyl or a group ;

Ri is methyl, lower alkyl, lower alkenyl or lower alkynyl ("lower" in this respect meaning having from one to four, more preferably one to three, carbon atoms); Ri and R₂ are each hydrogen, methyl, or form a bond to provide a double bond; and Q is

wherein R₄ is hydrogen or methyl, preferably methyl. Use of CYP3 A4/5 inhibitors in combination with such epothilone compounds metabolized by CYP3A4/5 enzymes provides an enhanced anti-cancer allowed for a reduced dosage of the epothilone compounds as compared with when the epothilone compounds are administered in the absence of the CYP3A4/5 inhibitors.

Claims

CLAIMSWhat is claimed is:

1. Use of ixabepilone in combination with at least one CYP3A4/5 inhibitor in preparing a medicament for treatment of cancer.

2. The Use of claim 1, wherein the combined Use provides an enhanced anti-cancer effect, so that a substantially reduced dose of ixabepilone may be administered to achieve the same anti-cancer effect as when ixabepilone is administered at a standard recommended dose and in the absence of the CYP3A4/5 inhibitor.

3. Use according to claims 1 or 2, wherein the CYP3A4 inhibitor is selected from lapatinib and ketoconazole.

4. The Use according to claim 3, wherein the the CYP3A4 inhibitor comprises ketoconazole prepared for administration of at least about 100 to 400 mg per day.

5. The Use according to claims 1, 2 , or 4, wherein the medicament is pprreeppaarreedd ffoorr UUssee ooff aabboouutt 1155 ttoo s about 30 mg/m² of ixabepilone to be intraveneous administered every three weeks.

6. The Use according to claims 1, 2 or 4, wherein the medicament is prepared for Use of ixabepilone to be orally administered in the form of an enteric coated bead.

7. The Use according to claim 3, wherein said ketoconazole is administered daily for at least one day before administration of said ixabepilone.

8. The Use according to claim 7 wherein said ketoconazole is administered daily concurrently with said ixabepilone.

9. The Use according to claim 1 wherein said cancer is selected from breast cancer, prostate cancer, lung cancer, pancreatic cancer, ovarian cancer, cervical cancer, cancer of the endometrium, and/or colon cancer.

10. The Use according to claim 8 wherein said cancer is metastatic breast cancer.