April 9, 2009 -- Scientists are developing a new drug to slow advanced prostate cancer that resists other androgen hormone treatment.
In the advance online edition of Science, researchers report initial results from the first test if the drug, called MDV3100, in men with advanced prostate cancer.
Those men had advanced prostate cancer that had become resistant to drug therapy that targets receptors for the hormone androgen.
In the study, 30 patients took a daily pill containing either 30 or 60 milligrams of MDV3100.
Most patients, 22 out of 30, had a sustained drop in their prostate-specific antigen (PSA) level for at least 12 weeks, and 13 of those patients saw their PSA level drop by more than half. In men who have prostate cancer, PSA levels are used as a benchmark for how well their treatment is going.
MDV3100 was "well tolerated," write the researchers, who included Charles Sawyers, MD, an investigator with the Howard Hughes Medical Institute and the chairman of the human oncology and pathogenesis program at Memorial Sloan-Kettering Cancer Center in New York.
The findings are preliminary, but "we're seeing quite impressive clinical results," Sawyers tells WebMD.
A study testing higher doses of MDV3100 in 110 additional men with advanced prostate cancer is already under way.
Full results from those patients will probably be published within a year, and an even larger trial is set to begin this year, Sawyers says. He adds that at much higher doses than 60 milligrams, MDV3100 showed "some side effects, primarily fatigue," but that "there's pretty strong evidence that you can take a dose that's very effective that will be well tolerated."
If all goes well with further studies, MDV3100 might be up for FDA consideration in three to four years, Sawyers says.
"The proof that the FDA would like to see, and I think that the clinical community and patients would like to see as well, is that it prolongs survival compared to standard care," Sawyers says. "In order to answer that question, it takes several years to follow men out long enough to get results on survival."
Sawyers and several colleagues are co-inventors on patent applications covering MDV3100 and related compounds; Sawyers is also a consultant to Medivation Inc., the company that has licensed MDV3100.
To read more of Sawyers' comments on MDV3100, visit WebMD's news blog.