Water soluble paclitaxel derivatives

Abstract

Disclosed are water soluble compositions of paclitaxel and docetaxel formed by conjugating the paclitaxel or docetaxel to a water soluble polymer such as polyglutamic acid, poly-aspartic acid or poly-lysine. Also disclosed are methods of using the compositions for treatment of tumors, auto-immune disorders such as rheumatoid arthritis. Other embodiments include the coating of implantable stents for prevention of restenosis.

Description

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™) 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 ...

AI Technical Summary

Benefits of technology

[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.

[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).

[0023] This method may include any of the imaging techniques discussed above in which a paclitaxel-chelator-chelated metal is administered to a subject and detected in a tumor. This step provides a cost effective way of determining that a particular tumor would not be expected to respond to DTPA-paclitaxel therapy in those cases where the drug does not get into the tumor. It is contemplated that if an imaging technique can be used to predict the response to paclitaxel and to identify patients that are not likely to respond, great expense and crucial time may be saved for the patient. The assumption is that if there is no reasonable amount of chemotherapeutic agent deposited in the tumor, the probability of tumor response to that agent is relatively small.

[0027] An embodiment of the invention is, therefore, an implantable medical device, wherein the device is coated with a composition comprising paclitaxel or docetaxel conjugated to poly-glutamic acids or water soluble polyamino acids in an amount effective to inhibit smooth muscle cell proliferation. A preferred device is a stent coated with the compositions of the present invention as described herein, and in certain preferred embodiments, the stent is adapted to be used during or after balloon angioplasty and the coating is effective to inhibit restenosis.

Problems solved by technology

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.

Additionally, polymer-drug conjugates may act as drug depots for sustained release, producing prolonged drug exposure to tumor cells.

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