Drug Beneficial in Castration-Resistant Prostate Cancer

Phase 1-2 study demonstrates antitumor activity of new androgen-receptor antagonist MDV3100

THURSDAY, April 15 (HealthDay News) -- In men with progressive, metastatic, castration-resistant prostate cancer, the new treatment MDV3100 -- an androgen-receptor antagonist -- has shown promising antitumor activity, according to a study published online April 15 in The Lancet.

Howard I. Scher, M.D., of the Memorial Sloan-Kettering Cancer Center in New York City, and colleagues performed a phase 1-2 study of 140 men who were enrolled in dose-escalation cohorts and started with a daily MDV3100 dose of 30 mg. The final daily doses studied were 30, 60, 150, 240, 360, 480 and 600 mg.

The researchers found that all doses of MDV3100 were associated with antitumor effects, and observed decreases in serum prostate-specific antigen of 50 percent or more in 78 (56 percent) patients, responses in soft tissue in 13 (22 percent) of 59 patients, stabilized bone disease in 61 (56 percent) of 109 patients, and conversion from unfavorable to favorable circulating tumor cell counts in 25 (49 percent) of 51 patients. They also found that 240 mg was the maximum tolerated dose for sustained treatment (more than 28 days), and that dose-dependent fatigue -- which occurred in 16 (11 percent) of patients and generally resolved after dose reduction -- was the most common grade 3 to 4 adverse event.

"MDV3100 could have the potential to significantly change treatment options in metastatic disease, even in the post-chemotherapy setting in which hormonal manipulations might have more use than was previously thought," the authors write.

This study was partly supported by Medivation, and several authors disclosed financial relationships with the company. A co-author is a co-inventor of patents filed by the University of California in Los Angeles, that cover MDV3100.

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