Presented at ASCO GU by Stolten and colleagues was abstract 244 that described the responses African American men had to abiraterone (Zytiga) in a retrospective cohort study of men seen at a single institution.  Stolten included differences in the men including their age at diagnosis, prior enzalutamide (Xtandi) and/or docetaxel (chemotherapy) use, as well as baseline alkaline phosphatase, hemoglobin, and lactate dehydrogenase.  The primary outcome of interest was duration of treatment with Zytiga and they considered velocity of PSA decline, PSA response and progression as a secondary outcomes.

The treatment sample included 103 men with metastatic castration-resistant prostate cancer (mCRPC) who were treated with abiraterone during the period of the study. The sample size included 24 African American men and 79 Caucasian men.

The men had similar baseline ages of 61.8 years for African American men and 62.4 years for Caucasian men.

In terms of prior therapy with abiraterone, 4.2% of African American men and 6.3% of Caucasian men received treatment.

Prior treatment with docetaxel was more common, with 33.3% of African Americans and 29.1% of Caucasian men receiving treatment prior to inclusion in the study.

The median duration of treatment with abiraterone was not significantly different between African American and Caucasian men at 207 and 253 days, respectively.

There were no significant differences between African American men and Caucasian men in baseline laboratory values.

PSA decline was also similar between both groups of men.

Also, neither was the time to progression nor median time to PSA nadir significantly different between the two groups.

It looks as if both populations, African American men and Caucasian men have a similar response to being treated with Zytiga. This conclusion is limited by the small size of the sample as the small sample might not necessarily pick up subtle differences between the two groups.

African American men are disproportionately affected by prostate cancer, but their treatment sensitivity with Zytiga seems to be very similar to their Caucasian brothers.