The most serious adverse events were febrile neutropenia and neuropathy. Of the 101 patients in the combination group who died, 84 of the deaths (83.2%) were from prostate cancer, 8 were from unknown causes, and 1 was attributed to the study protocol. Of the 136 in the ADT-alone arm who died, 112 deaths (83.6%) were from prostate cancers, and 22 were from other or unknown causes; data on the causes of death in 2 patients were missing.
"The clinical interpretation of the data is that six cycles of docetaxel in addition to ADT represents an appropriate option for men with metastatic prostate cancer commencing ADT who are suitable for docetaxel therapy," Dr. Sweeney said in the plenary session.
Dr. Michael J, Morris, the invited discussant, pointed out that the superior overall survival seen with the combination in this study far outstrips that of other drugs tried in this population, with median overall survival benefits ranging from 2.2 to 5.2 months.
"The investigators have adequately shown that high-volume patients with castration-sensitive metastatic disease can benefit from upfront docetaxel," he said. "But there is insufficient data at this after 29 months of median follow-up to recommend that low-volume patients with castration-sensitive disease undergo chemotherapy. We need to optimize the distinction between those who benefit from chemotherapy and those who don’t."
Dr. Morris of Memorial Sloan–Kettering Cancer Center and of Weill Cornell Medical College in New York was not involved in the study.
The study was funded by the National Cancer Institute. Dr. Sweeney disclosed serving in a consulting or advisory role to Astellas Pharma, BIND Biosciences; Bionomics, Exelixis, Genentech, Janssen Pharmaceuticals, Roche and Sanofi. Dr. Morris disclosed consulting/advising Astellas, Bayer, Janssen, Millennium, and Progenics, stock ownership in Biogen Idec, Procter & Gamble, and Teva, and research funding from Agensys, Algeta, Bayer, Medivation, and Sanofi. Dr. Hudis served as a DSMB Chair for Genentech and received research grants from Onyx Pharmaceuticals and Merck & Co.