ORLANDO—An investigational drug called abiraterone acetate may improve the chances of survival among men with metastatic castration-resistant prostate cancer (CRPC) whose disease is progressing after receiving docetaxel-based chemotherapy, according to new findings.
In a phase 3 multinational study, investigators randomized 797 such patients to receive abiraterone acetate plus prednisone and 398 to receive placebo plus prednisone. The median follow-up was 12.8 months.
Abiraterone acetate prolonged survival by a median of approximately four months, lead researcher Howard I. Scher, MD, of Memorial Sloan Kettering Cancer Center (MSKCC) in New York, reported at the fourth annual Genitourinary Cancers Symposium. Abiraterone acetate recipients had a 35% decreased risk of death relative to the placebo group.
Dr. Scher, who is Chief of the Genitourinary Oncology Service at MSKCC’s Sidney Kimmel Center for Urologic and Prostate Cancers, and his collaborators also observed improvements in secondary end points attributable to abiraterone acetate, such as time to PSA progression, radiographic progression-free survival, and PSA response rate.
Abiraterone acetate displayed a favorable safety profile that was generally similar to that of placebo, Dr. Scher said. The more common adverse events associated with the drug included fluid retention, hypokalemia, liver function test abnormalities, and hypertension.
These results establish that considering CRPC to be hormone resistant “may deny patients a safe and life-prolonging treatment,” Dr. Scher told attendees.
Abiraterone acetate inhibits androgen biosynthesis in the testes, adrenal glands, and the prostate tumor, Dr. Scher’s group explained in a poster presented at the symposium. The result is plasma testosterone levels in the 1-2 ng/mL range—which is significantly lower than is achieved with conventional hormonal therapies—and a decrease in androgens within prostate tumors.
Johnson & Johnson, which is developing the new drug, funded the study.