Dr Lowentritt on the Rationale for Investigating Real-World PSA Response to AR Inhibitors in mCSPC

Benjamin H. Lowentritt, MD, FACS, director, Minimally Invasive Surgery and Robotics, Chesapeake Urology, discusses the background and rationale for conducting a real-world retrospective study of prostate-specific antigen (PSA) responses generated from second-generation androgen receptor (AR) inhibitors in patients with metastatic castration-sensitive prostate cancer (mCSPC).

In a presentation at the 2023 American Urological Association Annual Meeting, Lowentritt and colleagues presented data from a real-world study that evaluated patients treated with a next-generation AR inhibitor: apalutamide (Erleda), enzalutamide (Xtandi), or abiraterone acetate (Zytiga). Findings showed that treatment with apalutamide correlated with superior PSA response rates and time to castration resistance compared with enzalutamide or abiraterone acetate for patients treated in community settings. The 1-year PSA90 (defined as a 90% decline in PSA from baseline) response rates were 72.3%, 61.6%, and 54.7% for apalutamide, enzalutamide, and abiraterone acetate, respectively.

This study examined data extracted from medical record from 95 urology groups around the United States, gathered from a third-party data company, and investigators looked at specific end points that were attainable through data derived from electronic medical records, Lowentritt says. These end points included evaluating patients’ PSA response and the depth of response, specifically PSA90, or patients reaching a PSA that was undetectable that was less than 0.2 ng/mL after starting with a PSA of more than 0.2 ng/mL at baseline, Lowentritt says. Additionally, investigators also looked for time to castration resistance, he adds.

Investigators identified 1739 evaluable patients who met the inclusion criteria, and the groups were divided similarly between those who received apalutamide, enzalutamide, or enzalutamide after their respective FDA approvals, Lowentritt concludes.