Survival with frontline abiraterone higher for African American vs White men with mCRPC

Overall survival (OS) for patients with metastatic castration-resistant prostate cancer (mCRPC) receiving frontline abiraterone acetate (Zytiga) was higher for African American (AA) versus non-Hispanic White men, according to a retrospective analysis published in the journal JAMA Network Open.1

Specifically, the study showed that among newly diagnosed patients with mCRPC who received the androgen receptor pathway inhibitor abiraterone in the first-line setting, the median overall survival (OS) was 6 months higher for AA men versus White men.

“Prior research suggests that abiraterone is associated with greater clinical benefit for African American patients than for White patients with mCRPC. This real-world cohort study affirms these findings and is, to our knowledge, the first one to find that first-line abiraterone was associated with improved overall survival among African American patients compared with White patients,” the study authors wrote.

The retrospective cohort study used a nationwide electronic health record–derived database of 3808 men who underwent frontline treatment for mCRPC at about 800 clinical sites between January 1, 2012, and December 31, 2018.

“Propensity score–based inverse probability of treatment weighting was applied to reduce imbalance in measured confounders between patients receiving first-line abiraterone vs other first-line therapies,” the researchers explained in their paper.

Among the overall 3808-patient population, 68.7% (n = 2615) were White and 10.6% (n = 404) were AA. Of the 3808 patients, 1729 (45.4%) received abiraterone, including 1202 White patients and 170 AA patients. For some of their analyses, the researchers used the cohort of patients among the overall population who received first-line treatment with the androgen receptor pathway inhibitor enzalutamide (Xtandi) as a comparator.

In the abiraterone-treated population, the median OS was 23 months for AA men versus 17 months for White men (inverse probability of treatment weighting HR, 0.76; 95% CI, 0.60-0.98).

Among AA patients, OS was the same between those receiving first-line abiraterone and those treated with frontline enzalutamide, with a median OS of 24 months for both groups (inverse probability of treatment weighting HR, 1.05; 95% CI, 0.74-1.50). In contrast, among White patients, the median OS was lower among those receiving abiraterone, at 17 months versus 20 months for those receiving enzalutamide (inverse probability of treatment weighting HR, 1.21; 95% CI, 1.06-1.38).

In their concluding remarks, the authors wrote that the median OS difference between the 2 races, “may be due to decreased effectiveness of first-line abiraterone relative to other first-line therapies among White patients.”

Regarding next steps, the authors wrote, “Future prospective studies should assess drivers of differential abiraterone outcomes in mCRPC between African American and non-Hispanic White men, including differences in genetic factors and socioeconomic status, to inform treatment strategies.”

Abiraterone acetate currently has FDA-approved indications for use in combination with prednisone for the treatment of patients with mCRPC, as well as for the treatment of patients with metastatic high-risk castration-sensitive prostate cancer.

Reference

1. Marar M, Long Q, Mamtani R, et al. Outcomes among African American and non-Hispanic White men with metastatic castration-resistant prostate cancer with first-line abiraterone. JAMA Netw Open. 2022;5(1):e2142093. doi: 10.1001/jamanetworkopen.2021.42093