There may be cause for celebration among men with aggressive prostate cancer for whom traditional anti-androgen drug therapy has become ineffective.

A new study, headed by Charles L. Sawyers of Memorial Sloan-Kettering Cancer Center in New York, released findings which are encouraging.

In a phase II clinical trial of 30 men with anti-androgen resistant prostate cancer, 13 (43%) showed declines in PSA levels; some by 50%. This is meaningful because PSA is the blood level of the biomarker for tumor growth.

Traditional anti-androgen therapy works by decreasing androgen hormone production thereby denying the tumor cells the very hormones that make them grow; sort of starving them. However, these cancer cells can respond by developing an increased number of receptor sites which enhances their ability to suck up more hormone.

The new drug, developed by San Francisco based Medivation and trialed in this study, works differently. It actually blocks the androgen receptors on the tumor cells so that they are unable to absorb these hormones.

Other studies in men and mice have not only shown reduction of biomarker blood levels for tumor growth, but have also shown significant reduction in tumor size.

Although this drug, labeled MDV3100, is not available for general use at this time, stage III clinical studies will be taking place soon. Depending on these results, we may look forward to adding a new weapon to our arsenal of prostate cancer fighting drugs.