Positive Phase 3 clinical trial results for the drug MDV3100 in men whose prostate cancers had progressed after failing hormonal therapy and chemotherapy have recently been reported in a special edition of the Prostate Cancer Foundation Newsletter, November 7th, 2011 (see http://www.pcf.org/site). Such positive results were observed that the trial was stopped early and the drug provided to men who had been previously receiving the placebo. MDV3100 was found to increase the median survival time by 4.8 months and provided a 37% reduction in the risk of death when compared to placebo. Some men had more durable remissions while some did not respond. Based on these results, the drug’s developers, Medivation Inc. and Astellas Pharma Inc., plan to submit MDV3100 to the Food and Drug Administration for approval in 2012. MDV3100 has been under clinical development in advanced prostate cancer patients who have already received chemotherapy with taxotere (docetaxel) as well as those who have not been treated with taxotere. MDV3100 works by blocking the androgen receptor (which is the engine that drives prostate cancer progression) at three distinct points in the cell-signaling pathway. The drug blocks testosterone (the fuel that drives the engine) from binding to the androgen receptor (the engine), impedes movement of the androgen receptor to the nucleus of prostate cancer cells (nuclear translocation) and inhibits binding to DNA. MDV3100 has been described in an earlier blog (February 18th, 2011) on this website.
Stopping of a clinical trial and offering the drug to patients taking the placebo had occurred earlier this year with the FDA-approved drug Zytiga (abiraterone acetate). Zytiga affects prostate cancer progression by shutting off the supply of testosterone, the fuel that drives the cancer engine. Using both MDV3100 and Zytiga together seems to be a very logical idea. A Phase 3 trial is already underway in hormone-resistant (refractory) prostate cancer patients who have never received chemotherapy. The results are not yet available but the trend will be to use both drugs earlier in the history of prostate cancer patients. They could possibly be used to potentially cure patients with high-risk cancer who had not yet been treated surgically.