A Trial to Find Out if REGN4336 is Safe and How Well it Works Alone and in Combination With Cemiplimab for Adult Participants With Advanced Prostate Cancer

Key Inclusion Criteria:

1. Histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma
2. Metastatic, castration-resistant prostate cancer (mCRPC) with PSA value at screening ≥4 ng/mL that has progressed within 6 months prior to screening as defined in the protocol
3. Has progressed upon or intolerant to ≥2 lines prior systemic therapy approved in the metastatic and/or castration-resistant setting (in addition to androgen deprivation therapy [ADT]) including at least one second-generation anti-androgen therapy (e.g. abiraterone, enzalutamide, apalutamide, or darolutamide)

Key Exclusion Criteria:

1. Has received treatment with an approved systemic therapy within 3 weeks of dosing or has not yet recovered (ie, grade ≤1 or baseline) from any acute toxicities
2. Has received any previous systemic biologic therapy within 5 half-lives of first dose of study therapy
3. Has received prior PSMA-targeting therapy
4. Any condition that requires ongoing/continuous corticosteroid therapy (>10 mg prednisone/day or anti-inflammatory equivalent) within 1 week prior to the first dose of study therapy
5. Ongoing or recent (within 5 years) evidence of significant autoimmune disease that required treatment with systemic immunosuppressive treatments
6. Encephalitis, meningitis, neurodegenerative disease (with the exception of mild dementia that does not interfere with activities of daily living [ADLs]) or uncontrolled seizures in the year prior to first dose of study therapy
7. Uncontrolled infection with human immunodeficiency virus (HIV), hepatitis B or hepatitis C infection; or diagnosis of immunodeficiency

NOTE: Other protocol defined Inclusion/Exclusion Criteria apply