Accumulating data from patients with progressive, castration-resistant prostate cancer enrolled in a phase I-II study of MDV3100 show this novel antiandrogen has durable antitumor activity in both pre- and post-chemotherapy populations.
The clinical trial program evaluating MDV3100 for treatment of prostate cancer began in July 2007. The phase I dose-escalation study and phase II expansion trial enrolled 140 patients, including 65 chemotherapy-naïve men and 75 men who were post-docetaxel (Taxotere). Doses studied ranged from 30 mg/day to 600 mg/day. Outcomes based on data collected through April 2009 were published in Lancet (2010; 375:1437-46).
In her presentation at the AUA annual meeting in Washington, first author Celestia Higano, MD, presented the analysis of the long-term data since the data cutoff of April 2009 for the original Lancet report. This included follow-up of 44 patients remaining in the study who were followed for efficacy and safety per protocol through September 2010. With an additional 18 months of follow-up, the median time to PSA progression (defined per protocol as a ≥25% increase from baseline PSA) has not yet been met for the 65 chemotherapy-naïve patients and is 45 weeks for the 75 post-chemotherapy patients. Median time to PSA progression by Prostate Cancer Clinical Trials Working Group 2 (PCWG2) criteria is 40 and 21 weeks, respectively. Median time to radiographic progression is 56 weeks for the chemotherapy-naïve patients and 25 weeks in the post-chemotherapy subgroup.