The primary objectives of the study in Dose Escalation are to evaluate safety, tolerability, and pharmacokinetics (PK) of REGN5678 alone and in combination with cemiplimab and in Dose Expansion are to assess efficacy, as measured by objective response rate (ORR) per modified Prostate Cancer Working Group 3 (PCWG3) criteria, of REGN5678 in combination with cemiplimab.
The secondary objectives of the study in Dose Escalation are to assess efficacy, as measured by ORR per modified PCWG3 criteria, of REGN5678 in combination with cemiplimab and in Dose Expansion are to characterize the safety profile in each expansion cohort and to characterize the PK of REGN5678 in combination with cemiplimab. Secondary objectives in both Dose Escalation and Dose Expansion are to assess efficacy of REGN5678 in combination with cemiplimab, as measured by additional criteria and to assess immunogenicity of REGN5678 in combination with cemiplimab.
Inclusions/Exclusions: Histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma. Metastatic, castration-resistant prostate cancer (mCRPC) with PSA value at screening. Has received any previous systemic biologic therapy within 5 half-lives of first dose of study therapy. Has received prior PSMA-targeting therapy