Black men have a 60% greater incidence of being diagnosed with prostate cancer and nearly a 2.5-fold greater risk of mortality from the disease, yet the underlying cause for this increased mortality remains controversial. The extent to which race affects response to therapy in prostate cancer is not clear. Black men are disproportionately underrepresented in phase 3 studies of many newly approved agents for prostate cancer, including abiraterone acetate.

Interestingly, in a hypothesis-generating retrospective subset analysis of the COU-302 study, black patients randomized to abiraterone acetate demonstrated a trend towards a higher rate of 90% decline in PSA (53.3 vs 30.8%) and time to PSA progression (16.5 vs 11.1 months) compared to the overall population. Unfortunately, only 28 of 1088 patients were black, and 15 of these subjects were randomized to abiraterone acetate.

Ramalingam and colleagues reported in the June 2017 issue of Urologic Oncology on our single-institution, case-controlled retrospective analysis of the off-study use of abiraterone acetate to follow up on these provocative findings. Interestingly, we found trends in favor of black men having greater PSA response, depth of response, time to progression, and overall survival. Statistically significant differences were found in the proportion of patients achieving a >50% PSA level decline (black, 68.9%; white, 48.9% [P=0.028]) and >30% PSA level decline (black, 77.8%; white, 54.4%) [P=0.008]). There was also a strong trend toward more primary abiraterone acetate-refractory disease (ie, PSA increase as best response) in white than in black patients. Thus, black men with mCRPC may have a higher PSA response and lower primary resistance to abiraterone acetate treatment than white men with mCRPC. These findings suggest that the hormonal axis involved in mCRPC may be more prevalent in black men than in others, resulting in a greater likelihood of PSA response.

For clinicians today, it is important to recognize that, although black men may have characteristics of more aggressive disease (eg, a more rapid time from diagnosis to castration resistance), it’s possible that their response to newer androgen axis-targeted agents such as abiraterone acetate will be good.