Medivation, Inc. and Astellas Pharma Inc. have announced positive results on all efficacy endpoints from the phase III AFFIRM trial of the investigational drug MDV3100, an oral once daily androgen receptor signaling inhibitor, in men with prostate cancer previously treated with chemotherapy.

Findings include the following:

• Men taking MDV3100 lived for a median of 18.4 months, compared with 13.6 months for men taking placebo (p<0.0001; hazard ratio [HR] =0.631).

• MDV3100 also met all secondary endpoints, including radiographic progression-free survival (8.3 vs. 2.9 months; p < 0.0001; HR=0.404), soft tissue response rate (28.9% vs. 3.8%; p < 0.0001) and time to PSA progression (8.3 vs. 3.0 months; p < 0.0001; HR=0.249).

• PSA declines of ≥ 50% were more common in the MDV3100 group than in the placebo group (54.0% vs. 1.5%; p < 0.0001), as were PSA declines of ≥ 90% (24.8% vs. 0.9%; p < 0.0001).

• MDV3100 was well tolerated; common adverse effects included fatigue, diarrhoea and hot flush.

These data will be highlighted in a late-breaking oral presentation at the upcoming Genitourinary Cancers Symposium later in the day.