A Study of Opevesostat (MK-5684) Versus Alternative Next-generation Hormonal Agent (NHA) in Metastatic Castration-resistant Prostate Cancer (mCRPC) Post One NHA (MK-5684-004)

Has presence of gastrointestinal condition

Is unable to swallow capsules/tablets

Has history of pituitary dysfunction

Has poorly controlled diabetes mellitus

Has clinically significant abnormal serum potassium or sodium level

Has any of the following at screening visit: Hypotension: systolic blood pressure (BP) \<110 mmHg, or uncontrolled hypertension: systolic BP ≥160mmHg or diastolic blood BP ≥90 mmHg, in 2 out of the 3 recordings with optimized antihypertensive therapy

Has a history of active or unstable cardio/cerebrovascular disease, including thromboembolic events

History or family history of long QTc syndrome

Has a history of seizure(s) within 6 months before providing documented informed consent (IC) or has any condition that may predispose to seizure within 12 months prior to the date of enrollment

Has a history of clinically significant ventricular arrhythmias or Mobitz II second degree or third-degree heart block without a permanent pacemaker in place

Has received a taxane-based chemotherapy for metastatic castration-resistant prostate cancer (mCRPC)

Has not adequately recovered from major surgery or have ongoing surgical complications

Is currently being treated with Cytochrome P450 (CYP450)-inducing antiepileptic drugs for seizures

Participants on an unstable dose of thyroid hormone therapy, as judged by the investigator, within 6 months before the start of the study intervention

Receives prior radiotherapy within 2 weeks before the first dose of study intervention, or radiation-related toxicities, requiring corticosteroids

Receives prior systemic anticancer therapy including investigational agents within 4 weeks before the first dose of study intervention

Has systemic use of strong Cytochrome P450 3A4 (CYP3A4) inducers and P-glycoprotein (P-gp) inhibitors within 2 weeks before the first dose of study intervention

Has received prior targeted small molecule therapy or NHA treatment within 4 weeks before the first dose of study intervention

Received a live or live-attenuated vaccine within 30 days before the first dose of study intervention

Has received an investigational agent or has used an investigational device within 4 weeks prior to study intervention administration

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

Diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form of immunosuppressive therapy within 7 days prior the first dose of study medication

Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis. Participants with previously treated brain metastases may participate provided they are radiologically stable, (ie, without evidence of progression) for at least 4 weeks as confirmed by repeat imaging performed during study screening, are clinically stable and have not required steroid treatment for at least 14 days prior to the first dose of study intervention

Has active autoimmune disease that has required systemic treatment in the past 2 years. Replacement therapy is allowed

Active infection requiring systemic therapy

Has concurrent active Hepatitis B virus and Hepatitis C virus infection

What this study is about