Recent data from the American Cancer Society estimates that there will be approximately 241,740 new cases of prostate cancer diagnosed in the United States in 2012 and approximately 28,170 men will die of prostate cancer during the same time period.1 The lifetime diagnosis rate for prostate cancer is approximately 17% (1 in 6), making prostate cancer the most common cancer in American men, second only to skin cancer. Prostate cancer is highly prevalent in older men, with nearly two-thirds of diagnoses occurring in men aged 65 years or older and an average age of diagnosis of 67 years. Prostate cancer is the second leading cause of cancer death in American men, behind only lung cancer; one man in 36 will die of prostate cancer in 2012.
In accordance with the significant health burden caused by prostate cancer, practice-changing data on this cancer type were presented at the 2012 American Society of Clinical Oncology Annual Meeting. One of the major prostate cancer trials presented at ASCO 2012 was the COU-AA-302 (also known to those in the field as the “302” trial).2 The abstract entitled “Interim analysis (IA) results of COU-AA-302, a randomized, phase III study of abiraterone acetate (AA) in chemotherapy-naive patients (pts) with metastatic castration-resistant prostate cancer (mCRPC)” was presented by Charles J. Ryan, MD, associate professor of clinical medicine, University of California, San Francisco, CA.
Prior to this presentation, previous studies had shown that AA, an androgen biosynthesis inhibitor, improves overall survival (OS) in patients with metastatic castrate-resistant prostate cancer (mCRPC) that had previously progressed on docetaxel. In COU-AA-302, the investigators aimed to compare the clinical benefit of administering AA plus prednisone vs placebo (PL) plus prednisone in patients with mCRPC who were chemotherapy-naïve and asymptomatic or mildly symptomatic. Coprimary end points for the study were radiographic progression free survival (rPFS) and overall survival (OS).
The investigators were pleasantly surprised to see that both survival data and secondary end points favored the AA arm. In response, the Independent Data Monitoring Committee unanimously recommended unblinding the study and crossing patients from placebo to AA at interim analysis (43% of total events). Although at the time of interim analysis, the investigators were unable to report the median rPFS and median OS for the abiraterone arm, the Grade 3/4 adverse events for the abiraterone arm vs placebo arm were similar and abiraterone was generally well-tolerated in this patient population.
“Data from the 302 trial looks exceptionally compelling in terms of delaying disease progression based upon the series of coordinates agreed to by the prostate cancer working group,” says Neal Shore, MD, FACS, Director, CPI, Carolina Urologic Research Center, Atlantic Urology Clinics, Myrtle Beach, SC. “Ultimately, I am very optimistic that we will see a survival benefit in the prechemotherapy population. We are making great strides in a population that we have come to call castrate-resistant prostate cancer, but indeed they are still sensitive to hormonal manipulation.”