The market for taxol-based anti-cancer drugs is getting increasinglycrowded, especially since Bristol-Myers Squibb in three years will loseits exclusive marketing rights in the U.S. for the only FDA-approvedtaxol product. At least seven other companies are currently poised tojump on the taxol bandwagon.The New York-based company will lose its rights to market Taxol(paclitaxel), which is approved for ovarian and breast cancers that donot respond to other treatments, in December 1997, five years after itreceived FDA approval. Bristol-Myers has been using paclitaxelsupplied by Hauser in the manufacture of Taxol, under an agreementwhich expires in July.The next, nearest-to-market drug is Taxotere (docetaxel), Rhone-Poulenc Rorer's taxol-like drug that uses a formulation based on theneedles of the European yew tree. Encouraging results of clinical trialsfor Taxotere as a treatment for cancer of the breast, ovary, lung andpancreas have been reported in clinical trials. On Monday, at theannual meeting of the American Society of Clinical Oncology inDallas, researchers at the University of Texas M.D. Anderson CancerCenter in Houston reaffirmed encouraging results for Taxotere inbreast cancer.The Center's Phase II study involved 33 patients with advancedmetastatic breast cancer who had received prior chemotherapy, andwho had not responded to anthracycline, a commonly used treatmentfor breast cancer. Of the group, 18 (55 percent) demonstrated a partialresponse, defined as a 50 percent or greater reduction in measurabletumor size. Six patients showed no response, and nine had diseaseprogression.The main toxicities identified were reversible neutropenia,myalgia/fatigue, skin toxicity and fluid retention, both of which couldbe moderately reduced by steroids."The results of this trial showed that Taxotere has the highest everreported anti-tumor activity in anthracycline-resistant patients," theresearchers stated. Bob Pearson, a spokesman for Collegeville, Pa.-based Rhone-Poulenc Rorer, said this statement referred to all drugstested for this condition, not just to other Taxotere trials.Meanwhile, other companies and research institutions are tryinginnovative approaches to the development and manufacture of taxol,including the development of semi-synthetic products. Because thePacific yew tree, the original source of taxol, is endangered, othersources of taxol are being sought. Some examples include:y Last week, Wayne, N.J.-based American Cyanamid Co. and Boulder,Colo.-based Hauser Chemical Research announced that they will worktogether to commercialize Hauser's compound paclitaxel, and todevelop new taxane-related drugs for cancer and other diseases. (SeeBioWorld Today, May 16, 1994, p. 4.) Hauser is developing a cultivarprogram, growing yew trees of different species in order to develop agene pool with the most desirable characteristics for future taxol-baseddrug development.y Scientists at the Scripps Research Institute in La Jolla, Calif.announced in February that they had completed the first total chemicalsynthesis of taxol, although not on a scale to permit production of thedrug in quantity.y Vestar Inc., of San Dimas, Calif., is working with a Canadianpharmaceutical company, Towers Phytochemical Ltd., to develop ageneric formulation of paclitaxel and a liposomal formulation.y InflaZyme Pharmaceuticals, of Vancouver, British Columbia, has anagreement to provide Yew Tree Pharmaceuticals, a U.K.-basedcompany, with paclitaxel.y Cytoclonal Pharmaceutics Inc., of Dallas, acquired a license fromMontana State University to a fungal system for taxol production afterscientists discovered a fungus growing on Pacific yew trees that, whenisolated, was found to produce low levels of taxol.y PHYTOpharmaceuticals Inc., of San Carlos, Calif., is using afermentation process that stimulates cells taken from the yew treesroots, leaves and stems to produce large quantities of taxol. n

-- Philippa Maister

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