medwireNews: An analysis of a US database shows that Black individuals who receive abiraterone acetate or enzalutamide for metastatic castration-resistant prostate cancer (mCRPC) have better overall survival (OS) than their White counterparts.
“These results are consistent with prior results from clinical studies in mCRPC populations involving docetaxel, sipuleucel-T and abiraterone,” said presenting author Megan McNamara (Duke Cancer Institute, Durham, North Carolina, USA) at the 2019 ASCO Genitourinary Cancers Symposium in San Francisco, California, USA.
Asked about why Black men appear to benefit to a greater degree from these drugs than White men, McNamara told medwireNews that she thinks “there are genetic differences in genes involved in androgen signaling and metabolism associated with race that might explain why African–Americans with mCRPC are more responsive to abiraterone and enzalutamide.”
She pointed out that one of the key next steps is to conduct “[p]rospective studies in mCRPC to validate this finding and collect correlative samples to understand the mechanism underlying the racial difference in survival.”
McNamara also believes that such analyses by race need to be conducted in earlier disease settings, such as in men with metastatic hormone-sensitive or high-risk localized disease, “where the potential for benefit may be even greater.”
The current study drew on the US Veterans Health Administration database to identify 787 Black and 2123 White men with mCRPC who received abiraterone acetate or enzalutamide between April 2013 and March 2018.
Over a median follow-up of 570 days for the Black group and 561 days for the White group, OS was significantly better for Black versus White men, at a median of 30 and 26 months, respectively.
This benefit in favor of Black men was also observed in multivariate analysis accounting for age and comorbidities, with a significant hazard ratio for death of 0.826.
McNamara noted that with regard to population-wide data, “it still holds true that African–American men have worse survival than White men,” with a prostate cancer mortality that is 2.5-fold greater than in White men.
“However, several studies have now shown that African–Americans appear to have better outcomes in response to prostate cancer treatments. This is a paradox that we need to better understand and may be due to the genetic differences I described above,” she concluded.
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