GPC Biotech AG announced the presentation of new in vitro data on the efficacy of satraplatin in tumour cells resistant to both Taxotere (docetaxel) and Taxol (paclitaxel). These data will be presented in a poster session in Florence, Italy at the 1st Conference on Cancer Therapeutics-Molecular Targets, Pharmacology and Clinical Applications, sponsored by the International Chemotherapy Society. The poster is entitled, "Efficacy of Satraplatin and its Metabolites is Maintained in Taxane-Resistant Tumours."
"The data being presented support the lack of cross resistance between satraplatin and the two taxanes that are currently approved for use as chemotherapeutic agents in the treatment of human cancers - Taxotere and Taxol," said Marcel Rozencweig, senior vice president, Drug Development of GPC Biotech. "We expect that many of the patients in the satraplatin Phase 3 registrational trial will have been pre-treated with and failed on a taxane-based therapy prior to entering our study."
The study evaluated the effect of satraplatin on two taxane-resistant cell lines. In this study, one of the cell lines expresses mutant tubulin, and the other cell line over-expresses P-glycoprotein (Pgp). These genetic alterations represent the two most significant known mechanisms of resistance to the taxane family of compounds. The P-glycoprotein resistance mechanism is also conferred on a number of other anticancer agents, including the common chemotherapy treatment, doxorubicin. The data showed that these two resistance mechanisms did not convey similar resistance to satraplatin.
Satraplatin is a member of the platinum family of compounds, but unlike platinum compounds currently on the market, satraplatin is orally administered. A registrational Phase 3 trial - the SPARC trial - for satraplatin in hormone-refractory prostate cancer (HRPC) has been initiated, following successful completion of a Special Protocol Assessment (SPA) by the US FDA. The trial is now expanding in Europe following receipt of a Scientific Advice letter from the European Organization for the Evaluation of Medicinal Products (EMEA). In the US, the FDA has also granted fast track designation to satraplatin as a second-line chemotherapy treatment for patients with HRPC. Positive results from a randomized, 50-patient study in HRPC were presented at the ASCO Annual Meeting in June 2003. These data demonstrated statistical significance in time to disease progression, doubling progression-free survival in the satraplatin-treated group versus the control group. Phase 2 trials have been successfully completed in HRPC, as well as in ovarian cancer and small-cell lung cancer.