Omer Kucuk, MD, Winship Cancer Institute of Emory University, Atlanta, GA, gives an update on a Phase II trial (NCT04207255) evaluating the first-in-class sphingosine kinase-2 (SK2) selective inhibitor, opaganib, in patients with metastatic castration-resistant prostate cancer (mCRPC) progressing on abiraterone or enzalutamide. SK2 catalyzes formation of sphingosine 1-phosphate, which promotes cancer growth. The safety lead-in cohorts (1a and 1b) have now been completed. Enrolment is underway for cohort 2, trialling abiraterone plus opaganib, and cohort 3, trialling enzalutamide plus opaganib. A total of 60 patients will be enrolled. The primary endpoint of the study is stable disease or better after four cycles. This interview took place during the 2021 Genitourinary Cancers Symposium.