Phase III randomized studies of mevrometostat and enzalutamide in metastatic prostate cancer (MEVPRO-1 and MEVPRO-2): trial protocols.

Phase I investigation of the enhancer of zeste homolog 2 inhibitor, mevrometostat, plus enzalutamide showed promising antitumor activity versus enzalutamide alone in patients with metastatic castration-resistant prostate cancer (mCRPC) (NCT03460977). MEVPRO-1 (open label) and MEVPRO-2 (double blind) are ongoing, global, phase III, randomized studies evaluating efficacy and safety of mevrometostat plus enzalutamide in patients with mCRPC. MEVPRO-1 will include ~600 patients with ≥12 weeks of prior abiraterone treatment, Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-2, testosterone ≤50 ng/dL, and life expectancy ≥6 months. MEVPRO-2 will include ~900 androgen receptor pathway inhibitor-naïve patients, with ECOG PS 0-1, testosterone ≤50 ng/dL, and life expectancy ≥12 months. Patients are randomized 1:1 to mevrometostat (875 mg twice daily with food) plus enzalutamide (160 mg once daily), or physician's choice of enzalutamide or docetaxel (MEVPRO-1) or enzalutamide (MEVPRO-2). Primary endpoint is radiographic progression-free survival (rPFS) per Response Evaluation Criteria in Solid Tumors 1.1 (soft tissue) and Prostate Cancer Working Group 3 criteria (bone) assessed by blinded independent central review. Overall survival is a secondary objective. Kaplan-Meier analysis will summarize time-to-event endpoints. Safety will be assessed. Results will evaluate whether mevrometostat plus enzalutamide can provide clinical benefit in patients with mCRPC.Clinical trial registration: www.clinicaltrials.gov identifiers are NCT06551324 (MEVPRO-1) and NCT06629779 (MEVPRO-2).