Drug drops PSA in men with prostate cancer

An experimental drug lowers prostate specific antigen levels — a marker for tumor growth — in men with advanced prostate cancer, U.S. researchers say.

Researchers at Memorial Sloan-Kettering Cancer Center in New York said most men with metastatic prostate cancer eventually build up resistance to the drugs that lower or block male hormones and develop a more aggressive form of the illness called castration-resistant prostate cancer, or hormone-refractory disease.

The study, published in the online version of the journal Science, said investigators studied two novel compounds, RD162 and MDV3100, and not only gained an understanding of their novel mechanism of action, but found that these agents showed activity in castration-resistant prostate cancer cells in culture and in mice.

The study also reports on a Phase 1/2 trial of MDV3100 in 30 patients with advanced castration-resistant prostate cancer and found that 22 out of 30 men showed declining PSA levels, and 43 percent had PSA levels fall by more than one-half.

Several years ago, the senior author, Dr. Charles Sawyers, and colleagues at the University of California in Los Angeles uncovered a potential reason why metastatic prostate cancer patients eventually relapse. This insight was used to discover RD162 and MDV3100, the researchers said.