The findings of early tests on a new experimental prostate cancer drug is giving hope to men diagnosed with the most fast-growing form of the disease that does not respond to current treatments. MDV3100 is made by San Francisco-based Medivation Inc. It is already completed Phase 1 and 2 clinical trials and is currently looking for FDA approval for larger-scale testing on approximately 1,200 patients.

The team led by Charles Sawyers of Memorial Sloan-Kettering Cancer Center in New York has been researching treatments for prostate cancer that has spread to other parts of the body. Different from typical antiandrogen cancer drugs, the new compounds seem to work by more effectively stoping the androgen receptors on the cancer-cell surface, even when the total number of receptors on the cells was high, as occurs during resistance. (Read “Vitamins Do Not Prevent Prostate Cancer, Study Finds.”)

Side effects don’t seem to be an issue, Sawyers said. “At high doses, fatigue has been a problem in some men — higher doses than are needed to get benefit,” he said. Even if MDV3100 stretches the lives of men with advanced prostate cancer, their tumors will most likely become resistant to the treatment.

However researchers hope the drug can be combined with another new drug, being developed by a different team, that stops cancer cells from making their own supply of androgens. “A very exciting possibility” is that a cocktail of these drugs will prevent men with early prostate cancer from ever reaching the drug-resistant stage, stated Kantoff, who heads one of several centers that are testing MDV3100.