Investigational drug shows promise in advanced prostate cancer

An investigational drug called MDV3100 has shown significant promise in lowering PSA levels in men with advanced prostate cancer who have no other option for cure.

The drug has also been shown to shrink prostate cancer lesions seen on imaging studies, according to findings from a multicenter study.

"We are encouraged by the benefits participants are experiencing from this research," said principal investigator Tomasz Beer, MD, of the Oregon Health & Science University Knight Cancer Institute, Portland.

Researchers collaborated to review a number of compounds that could most effectively block the androgen receptor. Two of the compounds evaluated, MDV3100 and RD162, were found to work well in cells in culture, shrink tumors in prostate cancer mice models, maintain tumor shrinkage for months, and prevent the androgen receptor from activating additional genes later in the process. Currently approved drugs cannot disable the receptor in this way.

In light of these discoveries, the biopharmaceutical company Medivation, Inc., licensed RD162 and MDV3100 from UCLA in 2006 and, in 2007, several sites began enrolling men with castration-resistant prostate cancer who had relapsed after treatment with conventional hormone therapy in phase I/II clinical trials of MDV3100.

Of the 30 men who initially received low doses of MDV3100, 22 showed declining PSA levels, and 13 of the 30 men had PSA levels fall by more than one-half. Further positive results from an additional 110 study participants with metastatic, castration-resistant prostate cancer who received MDV3100 at higher doses recently were reported at the Genitourinary Cancers Symposium in February 2009.

The findings are published in the online edition of Science.