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Water soluble paclitaxel derivativesRelated Patent Categories: Drug, Bio-affecting And Body Treating Compositions, Designated Organic Active Ingredient Containing (doai), Peptide Containing (e.g., Protein, Peptones, Fibrinogen, Etc.) DoaiWater soluble paclitaxel derivatives description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060111273, Water soluble paclitaxel derivatives. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS [0001] This application claims priority of U.S. Ser. No. 09/050,662 filed Mar. 30, 1998. FIELD OF THE INVENTION [0002] The present invention relates generally to the fields of pharmaceutical compositions to be used in the treatment of cancer, autoimmune diseases and restenosis. The present invention also relates to the field of pharmaceutical preparations of anticancer agents such as paclitaxel (Taxol.TM.) and docetaxel (Taxotere), in particular making paclitaxel water soluble by conjugating the drug to water soluble moieties. BACKGROUND OF THE INVENTION [0003] Paclitaxel, an anti-microtubule agent extracted from the needles and bark of the Pacific yew tree, Taxus brevifolia, has shown a remarkable anti-neoplastic effect in human cancer in Phase I studies and early Phase II and III trials (Horwitz et at, 1993). This has been reported primarily in advanced ovarian and breast cancer. Significant activity has been documented in small-cell and non-small cell lung cancer, head and neck cancers, and in metastatic melanoma. However, a major difficulty in the development of paclitaxel for clinical trial use has been its insolubility in water. [0004] Docetaxel is semisynthetically produced from 10-deacetyl baccatin III, a noncytotoxic precursor extracted from the needles of Taxus baccata and esterified with a chemically synthesized side chain (Cortes and Pazdur, 1995). Various cancer cell lines, including breast, lung, ovarian, and colorectal cancers and melanomas have been shown to be responsive to docetaxel. In clinical trials, docetaxel has been used to achieve complete or partial responses in breast, ovarian, head and neck cancers, and malignant melanoma. [0005] Paclitaxel is typically formulated as a concentrated solution containing paclitaxel, 6 mg per milliliter of Cremophor EL (polyoxyethylated castor oil) and dehydrated alcohol (50% v/v) and must be further diluted before administration (Goldspiel, 1994). Paclitaxel (Taxol.TM.) has shown significant activity in human cancers, including breast, ovarian, non-small cell lung, and head and neck cancers (Rowinsky and Donehower, 1995). It has also shown significant activity in patients with advanced breast cancer who had been treated with multiple chemotherapeutic agents (Foa et al., 1994). As with most chemotherapeutic agents, however, the maximum tolerated dose of paclitaxel is limited by toxicity. In humans, paclitaxel's major toxic effect at doses of 100-250 mg/m.sup.2 is granulocytopenia (Holmes et al., 1995); symptomatic peripheral neuropathy is its principal nonhematologic toxicity (Rowinsky et al., 1993). [0006] The amount of Cremophor EL necessary to deliver the required doses of paclitaxel is significantly higher than that administered with any other drug that is formulated in Cremophor. Several toxic effects have been attributed to Cremophor, including vasodilatation, dyspnea, and hypotension. This vehicle has also been shown to cause serious hypersensitivity in laboratory animals and humans (Weiss et al., 1990). In fact, the maximum dose of paclitaxel that can be administered to mice by i.v. bolus injection is dictated by the acute lethal toxicity of the Cremophor vehicle (Eiseman et al., 1994). In addition, Cremophor EL, a surfactant, is known to leach phthalate plasticizers such as di(2-ethylhexyl)phthalate (DEHP) from the polyvinylchloride bags and intravenous administration tubing. DEHP is known to cause hepatotoxicity in animals and is carcinogenic in rodents. This preparation of paclitaxel is also shown to form particulate matter over time and thus filtration is necessary during administration (Goldspiel, 1994). Therefore, special provisions are necessary for the preparation and administration of paclitaxel solutions to ensure safe drug delivery to patients, and these provisions inevitably lead to higher costs. [0007] Prior attempts to obtain water soluble paclitaxel have included the preparation of prodrugs of paclitaxel by placing solubilizing moieties such as succinate, sulfonic acid, amino acids, and phosphate derivatives at the 2'-hydroxyl group or at the 7-hydroxyl position (Deutsch et al., 1989; Mathew et al., Zhao and Kingston, 1991, 1992; Nicolaou et al., 1993; Vyas et al., 1995, Rose et al., 1997). While some of these prodrugs possess adequate aqueous solubility, few have antitumor activity comparable to that of the parent drug (Deutsch et al., 1989; Mathew et al., 1992; Rose et al., 1997). Several of these derivatives are not suitable for i.v. injection because of their instability in aqueous solution at neutral pH. For example, Deutsch et al. (1989) report a 2'-succinate derivative of paclitaxel, but water solubility of the sodium salt is only about 0.1% and the triethanolamine and N-methylglucamine salts were soluble at only about 1%. In addition, amino acid esters were reported to be unstable. Similar results were reported by Mathew et al. (1992). [0008] Recently, Nicolaou et al. (1993) reported the synthesis and in vitro biological evaluation of a novel type of prodrug termed "protaxols". These compounds possess greater aqueous solubility and are converted to paclitaxel as the active drug through an intramolecular hydrolysis mechanism. However, no in vivo data on the antitumor activity of protaxols are yet available. Greenwald et al. reported the synthesis of highly water-soluble 2' and 7-polyethylene glycol esters of paclitaxel (Greenwald et al., 1994). Using the strategy of polymer linkage, others have developed water-soluble polyethylene glycol (PEG)-conjugated paclitaxel (Li et al., 1996; Greenwald et al., 1996). Although these conjugates have excellent water solubility, their therapeutic efficacies are not better than free paclitaxel. Moreover, PEG has only two reactive functional groups at each end of its polymer chain, which effectively limit the amount of paclitaxel that PEG could carry (U.S. Pat. No. 5,362,831). [0009] Other attempts to solve these problems have involved microencapsulation of paclitaxel in both liposomes and nanospheres (Bartoni and Boitard, 1990). The liposome formulation was reported to be as effective as free paclitaxel, however only liposome formulations containing less than 2% paclitaxel were physically stable (Sharma and Straubinger, 1994). Unfortunately, the nanosphere formulation proved to be toxic. There is still a need therefore for a water soluble paclitaxel formulation that can deliver effective amounts of paclitaxel and docetaxel without the disadvantages caused by the insolubility of the drug. [0010] Another obstacle to the widespread use of paclitaxel is the limited resources from which paclitaxel is produced, causing paclitaxel therapy to be expensive. A course of treatment may cost several thousand dollars, for example. There is the added disadvantage that not all tumors respond to paclitaxel therapy, and this may be due to the paclitaxel not getting into the tumor. There is an immediate need, therefore, for effective formulations of paclitaxel and related drugs that are water soluble with long serum half lives for treatment of tumors, autoimmune diseases such as rheumatoid arthritis, as well as for the prevention of restenosis of vessels subject to traumas such as angioplasty and stenting. SUMMARY OF THE INVENTION [0011] The present invention seeks to overcome these and other drawbacks inherent in the prior art by providing compositions comprising a chemotherapeutic and/or antiangiogenic drug, such as paclitaxel, docetaxel, or other taxoid conjugated to a water soluble polymer such as a water soluble polyamino acid, or to a water soluble metal chelator. It is a further embodiment of the present invention that a composition comprising a conjugate of paclitaxel and poly-glutamic acid has surprising antitumor activity in animal models, and further that this composition is demonstrated herein to be a new species of taxane that has pharmaceutical properties different from that of paclitaxel. These compositions are shown herein to be surprisingly effective as anti-tumor agents against exemplary tumor models, and are expected to be at least as effective as paclitaxel, docetaxel, or other taxoid against any of the diseases or conditions for which taxanes or taxoids are known to be effective. The compositions of the invention provide water soluble taxoids to overcome the drawbacks associated with the insolubility of the drugs themselves, and also provide the advantages of improved efficacy and controlled release so that tumors are shown herein to be eradicated in animal models after a single intravenous administration, as well as providing a novel taxane. Poly-(l-glutamic acid) conjugated paclitaxel is shown in the examples hereinbelow to have a novel drug activity, in addition to having improved the delivery to the tumor and providing a controlled release. [0012] The methods described herein could also be used to make water soluble polymer conjugates of other therapeutic agents, contrast agents and drugs, including paclitaxel, tamoxifen, Taxotere, etopside, teniposide, fludarabine, doxorubicin, daunomycin, emodin, 5-fluorouracil, FUDR, estradiol, camptothecin, retinoids, verapamil, epothilones cyclosporin, and other taxoids. In particular, those agents with a free hydroxyl group would be conjugated to the polymers by similar chemical reactions as described herein for paclitaxel. Such conjugation would be well within the skill of a routine practitioner of the chemical art, and as such would fall within the scope of the claimed invention. Those agents would include, but would not be limited to etopside, teniposide, camptothecin and the epothilones. As used herein, conjugated to a water soluble polymer means the covalent bonding of the drug to the polymer or chelator. [0013] It is also understood that the water soluble conjugates of the present invention may be administered in conjunction with other drugs, including other anti-tumor or anticancer drugs. Such combinations are known in the art. The water soluble paclitaxel, docetaxel, or other taxoid, or in preferred embodiments the poly-(l-glutamic) acid conjugated paclitaxel (PG-TXL), of the present invention may, in certain types of treatment, be combined with a platinum drug, an antitumor agent such as doxorubicin or daunorubicin, for example, or other drugs that are used in combination with Taxol.TM. or combined with external or internal irradiation, that is to say, radiation administered by an external radiation source, or administered systemically, for example, by injection or ingestion of radioactive materials, such as a radioisotope containing formulation. [0014] Conjugation of chemotherapeutic drugs to polymers is an attractive approach to reduce systemic toxicity and improve the therapeutic index. Polymers with molecular mass larger than 30 kDa do not readily diffuse through normal capillaries and glomerular endothelium, thus sparing normal tissue from irrelevant drug-mediated toxicity (Maeda and Matsumura, 1989; Reynolds, 1995). On the other hand, it is well established that malignant tumors often have disordered capillary endothelium and greater permeability than normal tissue vasculature (Maeda and Matsumura, 1989; Fidler et al., 1987). Tumors often lack a lymphatic vasculature to remove large molecules that leak into the tumor tissue (Maeda and Matsumura, 1989). Thus, a polymer-drug conjugate that would normally remain in the vasculature may selectively leak from blood vessels into tumors, resulting in tumor accumulation of active therapeutic drug. The water soluble polymers, such as, in preferred embodiments PG-TXL, may have pharmacological properties different from non-conjugated drugs (i.e. paclitaxel). Additionally, polymer-drug conjugates may act as drug depots for sustained release, producing prolonged drug exposure to tumor cells. Finally, water soluble polymers (e.g., water soluble polyamino acids) may be used to stabilize drugs, as well as to solubilize otherwise insoluble compounds. At present, a variety of synthetic and natural polymers have been examined for their ability to enhance tumor-specific drug delivery (Kopecek, 1990, Maeda and Matsumura, 1989). However, only a few are known by the present inventors to be currently undergoing clinical evaluation, including SMANCS in Japan and HPMA-Dox in the United Kingdom (Maeda, 1991; Kopecek and Kopeckova, 1993). [0015] In the present disclosure, a taxoid is understood to mean those compounds that include paclitaxels and docetaxel, and other chemicals that have the taxane skeleton (Cortes and Pazdur, 1995), and may be isolated from natural sources such as the Yew tree, or from cell culture, or chemically synthesized molecules, and a preferred taxane is a chemical of the general chemical formula, C.sub.47H.sub.51NO.sub.14, including [2aR-[2a.alpha.,4.beta.,4.alpha..beta.,6.beta.,9.alpha.(.alpha.R,*,.beta.- S*), 11.alpha., 12.alpha., 12a.alpha., 12.beta..alpha.,]]-.beta.-(Benzoylamino)-.alpha.-hydroxybenzene propanoic acid 6,12b,bis(acetyloxy)-12-(benzoyloxy)-2a,3,4,4a,5,6,9,10,11,12,12a,12- b-dodecahydro-4,11-dihydroxy-4a,8,13,13-tetramethyl-5-oxo-7,11-methano-1H-- cyclodeca[3,4]benz-[1,2-b]oxet-9-yl ester. It is understood that paclitaxel and docetaxel are each more effective than the other against certain types of tumors, and that in the practice of the present invention, those tumors that are more susceptible to a particular taxoid would be treated with that water soluble taxoid or taxane conjugate. [0016] In those embodiments in which the paclitaxel is conjugated to a water soluble metal chelator, the composition may further comprise a chelated metal ion. The chelated metal ion of the present invention may be an ionic form of any one of aluminum, boron, calcium, chromium, cobalt, copper, dysprosium, erbium, europium, gadolinium, gallium, germanium, holmium, indium, iridium, iron, magnesium, manganese, nickel, platinum, rhenium, rubidium, ruthenium, samarium, sodium, technetium, thallium, tin, yttrium or zinc. In certain preferred embodiments, the chelated metal ion will be a radionuclide, i.e. a radioactive isotope of one of the listed metals. Preferred radionuclides include, but are not limited to .sup.67Ga, .sup.68Ga, .sup.111In, .sup.99mTc, .sup.90Y, .sup.114mSn and .sup.193mPt. [0017] Preferred water soluble chelators to be used in the practice of the present invention include, but are not limited to, diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), 1,4,7,10-tetraazacyclododecane-N,N',N,''N''' tetraacetate (DOTA), tetraazacyclotetradecane-N,N',N''N'''-tetraacetic acid (TETA), hydroxyethylidene diphosphonate (HEDP), dimercaptosuccinic acid (DMSA), diethylenetriaminetetramethylenephosphonic acid (DTTP) and 1-(.rho.-aminobenzyl)-DTPA, 1,6-diamino hexane-N,N,N',N'-tetraacetic acid, DPDP, and ethylenebis (oxyethylenenitrilo)-tetraacetic acid, with DTPA being the most preferred. A preferred embodiment of the present invention may also be a composition comprising .sup.111In-DTPA paclitaxel, and Na-DTPA-paclitaxel. [0018] In certain embodiments of the present invention, the paclitaxel, docetaxel, or other taxoid may be conjugated to a water soluble polymer, and preferably the polymer is conjugated to the 2' or the 7-hydroxyl or both of the paclitaxel, docetaxel, or other taxoid. Poly-glutamic acid (PG) is one polymer that offers several advantages in the present invention. First, it contains a large number of side chain carboxyl functional groups for drug attachment. Second, PG can be readily degraded by lysosomal enzymes to its nontoxic basic component, 1-glutamic acid, d-glutamic acid and di-glutamic acid. Finally, sodium glutamate has been reported to prevent manifestations of neuropathy induced by paclitaxel, thus enabling higher doses of paclitaxel to be tolerated (Boyle et al., 1996). Preferred polymers include, but are not limited to poly(l-glutamic acid), poly(d-glutamic acid), poly(dl-glutamic acid), poly(l-aspartic acid), poly(d-aspartic acid), poly(dl-aspartic acid), poly(l-lysine), poly(d-lysine), poly(dl-lysine), copolymers of the above listed polyamino acids with polyethylene glycol, polycaprolactone, polyglycolic acid and polylactic acid, as well as poly(2-hydroxyethyl 1-glutamine), chitosan, carboxymethyl dextran, hyaluronic acid, human serum albumin and alginic acid, with poly-glutamic acids being particularly preferred. At the lower end of molecular weight, the polymers of the present invention preferably have a molecular weight of about 1,000, about 2,000, about 3,000, about 4,000, about 5,000, about 6,000, about 7,000, about 8,000, about 9,000, about 10,000, about 11,000, about 12,000, about 13,000, about 14,000, about 15,000, about 16,000, about 17,000, about 18,000, about 19,000, about 20,000, about 21,000, about 22,000, about 23,000, about 24,000, about 25,000, about 26,000, about 27,000, about 28,000, about 29,000, about 30,000, about 31,000, about 32,000, about 33,000, about 34,000, about 35,000, about 36,000, about 37,000, about 38,000, about 39,000, about 40,000, about 41,000, about 42,000, about 43,000, about 44,000, about 45,000, about 46,000, about 47,000, about 48,000, about 49,000, to about 50,000 kD. At the higher end of molecular weight, the polymers of the present invention preferably have a molecular weight of about 51,000, about 52,000, about 53,000, about 54,000, about 55,000, about 56,000, about 57,000, about 58,000, about 59,000, about 60,000, about 61,000, about 62,000, about 63,000, about 64,000, about 65,000, about 66,000, about 67,000, about 68,000, about 69,000, about 70,000, about 71,000, about 72,000, about 73,000, about 74,000, about 75,000, about 76,000, about 77,000, about 78,000, about 79,000, about 80,000, about 81,000, about 82,000, about 83,000, about 84,000, about 85,000, about 86,000, about 87,000, about 88,000, about 89,000, about 90,000, about 91,000, about 92,000, about 93,000, about 94,000, about 95,000, about 96,000, about 97,000, about 98,000, about 99,000, to about 100,000 kD. Within these ranges, the ranges of molecular weights for the polymers are preferably of about 5,000 to about 100,000 kD, with about 20,000 to about 80,000 being preferred, or even about 25,000 to about 50,000 being more preferred. [0019] It is a further aspect of the invention that a composition of the invention such as PG-TXL may also be conjugated to a second lipophilic or poorly soluble antitumor agent such as camptothecin, epothilone, cisplatin, melphalan, Taxotere, etoposide, teniposide, fludarabine, verapamil, or cyclosporin, for example, or even to water soluble agents such as 5 fluorouracil (5 FU) or fluorodeoxyuridine (FUDR), doxorubicin or daunomycin. [0020] It is understood that the compositions of the present invention may be dispersed in a pharmaceutically acceptable carrier solution as described below. Such a solution would be sterile or aseptic and may include water, buffers, isotonic agents or other ingredients known to those of skill in the art that would cause no allergic or other harmful reaction when administered to an animal or human subject. Therefore, the present invention may also be described as a pharmaceutical composition comprising a chemotherapeutic or anti-cancer drug such as paclitaxel, docetaxel, or other taxoid conjugated to a high molecular weight water soluble polymer or to a chelator. The pharmaceutical composition may include polyethylene glycol, poly-glutamic acids, poly-aspartic acids, poly-lysine, or a chelator, preferably DTPA. It is also understood that a radionuclide may be used as an anti-tumor agent, or drug, and that the present pharmaceutical composition may include a therapeutic amount of a chelated radioactive isotope. Continue reading about Water soluble paclitaxel derivatives... 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