Combination therapy shows promising survival benefit in Black men with mCRPC

Interim results from the phase 2 PANTHER study (NCT03098836) suggest that Black men with metastatic castrate-resistant prostate cancer (mCRPC) show improved benefit from the combination hormonal therapy of apalutamide (Erleada) and abiraterone acetate (Zytiga) plus prednisone compared with White men.¹

Findings showed an improved median rPFS of 30 months among Black patients, compared with 15 months among White patients.

Although the combination therapy showed little benefit among White patients, the findings showed improved overall survival (OS), radiographic progression-free survival (rPFS), and time to prostate-specific antigen (PSA) progression among Black patients.

The data were presented at the 2023 American Society of Clinical Oncology Annual Meeting in Chicago, Illinois, and add to findings from the previously reported Abi Race trial (NCT01940276).²

In total, 93 men with androgen receptor pathway inhibitor naïve mCRPC were included in the study. Of those, 43 were Black and 50 were White. White patients (44%) in the study were more likely to have received prior docetaxel compared with Black patients (33%). A higher percentage of Black patients (23%) had diabetes compared with White patients (12%).

All participants in the study received 240 mg daily of oral apalutamide, 1000 mg daily of abiraterone, and 10 mg daily of prednisone until disease progression, unacceptable toxicity, or 2 years. The primary end point of the study was rPFS. Median follow-up for Black patients was 44 months, and median follow-up for White patients was 54 months.

Findings showed an improved median rPFS of 30 months among Black patients, compared with 15 months among White patients. At the time of analysis, 18 Black patients had an rPFS event, compared with 36 White patients.

Overall survival with the therapy combination was also improved among Black patients, who experienced a 2-year mortality rate of 14%, compared with 33% among White patients. Black patients also experienced greater declines in PSA levels compared with White patients, with 93% of Black patients experiencing a PSA decline of 50% of higher, compared with 68% of White patients.

In regard to safety, toxicity rates were acceptable among both patient cohorts. Black patients experienced higher rates of hyperglycemia, hypokalemia, and pain in extremities, and White patients experienced higher rates of fatigue.

“This research shows the importance of diversity in clinical trials. Without a larger percentage of Black participants, you would not pick up this important signal that Black men benefit differently than Whites. I wonder how many similar signals we are missing because we don’t have adequate diversity in studies. You can’t assume that a lack of benefit in White patients applies to Blacks,” said lead author Daniel J. George, MD, in a news release on the findings.³ George is a professor of medicine and surgery at Duke University School of Medicine in Durham, North Carolina.

The PANTHER study is still ongoing to assess long-term outcomes.

References

1. George DJ, Halabi S, Fleming MT, et al. A prospective trial of apalutamide and abiraterone acetate plus prednisone in Black and White men with metastatic castrate-resistant prostate cancer. J Clin Oncol. 2023;41(suppl):5015. doi:10.1200/JCO.2023.41.16_suppl.5015

2. George DJ, Heath EI, Sartor AO, et al. Abi Race: A prospective, multicenter study of black (B) and white (W) patients (pts) with metastatic castrate resistant prostate cancer (mCRPC) treated with abiraterone acetate and prednisone (AAP). J Clin Oncol. 2018;36(suppl):LBA5009. doi:10.1200/JCO.1028.36.18_suppl.LBA5009

3. Black men with metastatic prostate cancer may benefit from drug combination. News release. Duke Health. June 1, 2023. Accessed June 3, 2023. https://www.newswise.com/articles/black-men-with-metastatic-prostate-cancer-may-benefit-from-drug-combination