A Clinical Study of Ifinatamab Deruxtecan Based Treatment Combinations or as Monotherapy to Treat Metastatic Castrate Resistant Prostate Cancer (mCRPC) (MK-2400-01A/IDeate-Prostate02)

Prior treatment

• Has received prior treatment with taxane-based chemotherapy agent for metastatic castration-resistant prostate cancer (mCRPC).
• Received prior radiotherapy within 2 weeks of start of study intervention, or has radiation-related toxicities, requiring corticosteroids

Other illness

• Has any history of interstitial lung disease (ILD)/pneumonitis irrespective of steroid use (except for a history of radiation pneumonitis that did not require steroids), current ILD, clinical or radiographic suspicion of ILD for which the diagnosis of ILD cannot be ruled out
• Clinically severe pulmonary compromise resulting from intercurrent pulmonary illnesses
• Uncontrolled or significant cardiovascular disease
• History of pituitary dysfunction
• Poorly controlled diabetes mellitus
• History or current condition of adrenal insufficiency (eg, Addison's disease)
• Chronic steroid treatment (dose of \>10 mg daily prednisone equivalent), except for low-dose inhaled steroids (for asthma/chronic obstructive pulmonary disease), topical steroids (for mild skin conditions), or intra-articular steroid injections
• Known additional malignancy that is progressing or has required active treatment within the past 3 years
• Active autoimmune disease that has required systemic treatment in the past 2 years
• History of allogeneic tissue/solid organ transplant

Other

• The main exclusion criteria include but are not limited to the following:
• Known active central nervous system (CNS) metastases and/or carcinomatous meningitis

• The main inclusion criteria include but are not limited to the following:
• Has histologically- or cytologically-confirmed adenocarcinoma of the prostate without small cell histology
• Has prostate cancer progression while on androgen deprivation therapy (ADT) (or post bilateral orchiectomy) within 6 months before Screening
• Has current evidence of distant metastatic disease
• Has received prior treatment with 1 or 2 androgen receptor pathway inhibitors (ARPIs) and progressed during or after treatment
• Participants receiving bone resorptive therapy (including, but not limited to bisphosphonate or denosumab) must have been on stable doses for ≥4 weeks before allocation/randomization
• An Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 assessed within 10 days before allocation/randomization
• Has prior treatment with poly-ADP-ribose polymerase inhibitors (PARPi) if indicated by local approved regimen or were deemed ineligible to receive PARPi by the investigator