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)

Open to people ages 18 years and up

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

The main exclusion criteria include but are not limited to the following:

• 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)
• Has received prior treatment with taxane-based chemotherapy agent for metastatic castration-resistant prostate cancer (mCRPC).
• 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
• Received prior radiotherapy within 2 weeks of start of study intervention, or has radiation-related toxicities, requiring corticosteroids
• Known additional malignancy that is progressing or has required active treatment within the past 3 years
• Known active central nervous system (CNS) metastases and/or carcinomatous meningitis
• Active autoimmune disease that has required systemic treatment in the past 2 years
• History of allogeneic tissue/solid organ transplant