SAN ANTONIO The Southwest Oncology Group (SWOG) has announced the start of the first major phase III trial to compare the chemotherapy combination of docetaxel(Drug information on docetaxel) (Taxotere) and estramustine(Drug information on estramustine) phosphate (Emcyt) with the commonly used combination of mitoxantrone(Drug information on mitoxantrone) (Novantrone) and prednisone(Drug information on prednisone) for the treatment of advanced, hormone-refractory prostate cancer.
Patient enrollment is underway, and approximately 660 men are being recruited for the trial, which is being initiated by SWOG and funded by the National Cancer Institute in collaboration with the Cancer and Leukemia Group B and North Central Cancer Treatment Group.
Results of phase I/II studies have shown the combination of docetaxel and estramustine to be very active and well tolerated in patients with hormone-refractory prostate cancer, SWOG said in a news release.
The encouraging response rates seen thus far with the combination of docetaxel and estramustine provide hope that using a tolerable, more effective combination may prolong life in this group of difficult-to-treat patients, said SWOG study chair Daniel P. Petrylak, MD.
Dr. Petrylak is assistant professor of medicine, Columbia College of Physicians and Surgeons, and director of the Genitourinary Oncology Program, Columbia Presbyterian Center of New York-Presbyterian Hospital, the site where this treatment regimen was developed and first studied. The primary objectives of the study are to determine if the docetaxel/estra-mustine combination improves overall survival and progression-free survival when compared with the mitoxantrone/prednisone combination, and to compare toxicities related to the two treatments. Other objectives include assessments of the decline of prostate-specific antigen (PSA) levels and of quality of life among both treatment groups.
While prior clinical trials using single-agent chemotherapy have yielded objective response rates of 10% to 20% with subjective or stable response rates in another 20% to 40% of patients, no single agent or combination treatment has demonstrated a survival benefit for advanced, hormone-refractory prostate cancer patients in phase III trials. The reported survival rate in these trials has been less than a year, ranging from 5 to 11 months.
Palliative benefit can be achieved with the administration of mitoxantrone with corticosteroids; however, there is no evidence that survival is prolonged with this therapy. There is an obvious need for new therapies based on novel methods of inhibiting cancer growth, he said.
For the present phase III study, participants will be randomized at the SWOG Coordinating Center to receive one of two treatment regimens: oral estramustine taken three times daily for 5 days combined with intravenous docetaxel administered on the second day of treatment; or intravenous mitoxantrone administered every 3 weeks with twice-daily oral prednisone taken for 3 consecutive weeks. A maximum of 12 cycles of either treatment regimen will be administered.
For more information about this study (S9916), contact the National Cancer Institutes toll-free Cancer Information Service (CIS) at 1-800-4-CANCER.