Medivation and Astellas announced positive results from an interim analysis of the Phase 3 AFFIRM trial of MDV3100 in men with advanced prostate cancer previously treated with chemotherapy. AFFIRM is a randomized, double-blind, placebo-controlled, multinational trial evaluating MDV3100 (160mg/day) versus placebo in 1,199 men with advanced prostate cancer who were previously treated with docetaxel-based chemotherapy. MDV3100 met the study’s pre-specified interim efficacy stopping criteria, demonstrating a clinically meaningful and statistically significant (P<0.0001) improvement in overall survival (OS) compared with placebo. MDV3100 produced a 4.8-month advantage in median OS compared with placebo. The estimated median survival for men treated with MDV3100 was 18.4 months compared with 13.6 months for men treated with placebo. MDV3100 provided a 37% reduction in risk of death compared to placebo (HR=0.631). As a result, the Independent Data Monitoring Committee recommended that AFFIRM be stopped early and men who received placebo be offered MDV3100.

MDV3100 is an investigational, orally available androgen receptor signaling inhibitor. MDV3100 inhibits androgen receptor signaling in three distinct ways: it inhibits 1) testosterone binding to androgen receptors; 2) nuclear translocation of androgen receptors; and 3) DNA binding and activation by androgen receptors.

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