A Phase 3, Randomized, Open-label Study of MK-5684 Versus Alternative Abiraterone Acetate or Enzalutamide in Participants with Metastatic Castration-resistant Prostate Cancer (mCRPC) That Progressed On or After Prior Treatment with One Nextgeneration Horm

The purpose of this study is to assess the efficacy and safety of opevesostat plus hormone replacement therapy (HRT) compared to alternative abiraterone acetate or enzalutamide in participants with Metastatic Castration-resistant Prostate Cancer (mCRPC) previously treated with one next-generation hormonal agent (NHA). The primary study hypotheses are that opevesostat is superior to alternative abiraterone acetate or enzalutamide with respect to radiographic progression free survival (rPFS) per Prostate Cancer Working Group (PCWG) Modified Response Evaluation Criteria in Solid Tumors (RECIST 1.1) as assessed by Blinded Independent Central Review (BICR) and overall survival (OS), in androgen receptor ligand binding domain (AR LBD) mutation positive and negative participants.

For more information, please visit https://clinicaltrials.gov/study/NCT06136650

Inova Schar Cancer
8081 Innovation Park Dr. 
Fairfax Virginia 22031

• Have histologically or cytologically confirmed adenocarcinoma of the prostate without small cell histology
• Has current evidence of metastatic disease documented by either bone lesions on bone scan and/or soft tissue disease shown by computed tomography scan (CT)/magnetic resonance imaging (MRI)
• Has prostate cancer progression while receiving androgen deprivation therapy (ADT) (or post bilateral orchiectomy) within 6 months before screening
• Has an eastern clinical oncology group (ECOG) performance status of 0 or 1 assessed within 7 days before randomization
• Has ongoing androgen deprivation with serum testosterone <50 ng/dL (<1.7 nM)
• Has had prior treatment with Poly polymerase inhibitors (PARPi) or were deemed ineligible to receive treatment by the investigator or have refused PARPi treatment
• Has adequate organ function
• Has provided tumor tissue from a fresh core or excisional biopsy from soft tissue not previously irradiated. Samples from tumors progressing at a prior site of radiation are allowed
• Participants who have adverse event (AEs) due to previous anticancer therapies must have recovered to ≤Grade 1 or baseline. Participants with endocrine-related AEs who are adequately treated with hormone replacement therapy (HRT) or participants who have ≤Grade 2 neuropathy are eligible
• Additional inclusionary criteria will be reviewed during screening

• Has presence of gastrointestinal condition
• Is unable to swallow capsules/tablets
• Has history of pituitary dysfunction
• Has poorly controlled diabetes mellitus
• Has a history of active or unstable cardio/cerebro-vascular disease, including thromboembolic events
• Has clinically significant abnormal serum potassium or sodium level
• Has not adequately recovered from major surgery or have ongoing surgical complications
• Has known hypersensitivity to the components or excipients in abiraterone acetate, prednisone or prednisolone, enzalutamide, fludrocortisone, dexamethasone, or opevesostat.
• Has a "superscan" bone scan defined as an intense symmetric activity in the bones and diminished renal parenchymal activity on baseline bone scan such that the presence of additional metastases in the future could not be evaluated
• Has known additional malignancy that is progressing or has required active treatment within the past 3 years
• Has active autoimmune disease that has required systemic treatment in the past 2 years. Replacement therapy is allowed
• Additional exclusionary criteria will be reviewed during screening