Prostate Cancer Drug Zytiga May Extend Life

May 25, 2011 -- The newly approved prostate cancer pill Zytiga (abiraterone acetate) may extend life by up to four months in men with spreading cancer who have already been treated with chemotherapy, a study shows.

This survival gain "means quite a bit," says study researcher Howard I. Scher, MD, chief of the genitourinary oncology service at Memorial Sloan-Kettering Cancer Center in New York City. "These are a group of patients for whom there is no standard of care and it is particularly gratifying to see these results, to say the least."

The new study is published in the New England Journal of Medicine.

Prostate cancer is the most common cancer diagnosed in men besides skin cancer, according to the American Cancer Society. One out of every six men will be diagnosed with prostate cancer during his lifetime.

The new drug, which was approved by the FDA in April, inhibits a protein that helps form male hormones. The findings may help reshape the way doctors view and treat advanced prostate cancer.

The new study included 1,195 men with metastatic prostate cancer whose disease had progressed after chemotherapy. Those men who received steroid therapy along with the new pill survived for 14.8 months, on average, compared with 10.9 months seen among those who received a placebo along with steroids. This translated into a 34% reduction in risk of dying, the study shows.

This survival edge was considered so significant that men who received the placebo were permitted to switch to the new drug before the study was completed.

Men who took the new pill also saw greater responses in levels of prostate-specific antigen (PSA) than men who received placebo. Elevated levels of PSA may be a marker for prostate cancer.

The men who took Zytiga also showed improvements in disease-related symptoms and prostate cancer progression on imaging tests compared with men who received the placebo.

Zytiga side effects included fluid retention, high blood pressure, and a drop in blood potassium levels.