A Phase 1/2 Study of REGN5678 (Anti-PSMAxCD28) With or Without Cemiplimab (Anti-PD-1) in Patients With Metastatic Castration-Resistant Prostate Cancer and Other Tumors Associated With PSMA Expression
The main purpose of this study is to determine the safety, tolerability (how the body reacts to the drug\[s\]) and effectiveness (ability to treat the cancer) of REGN5678 (Nezastomig) alone, or in combination with cemiplimab. The study has 2 parts. The goal of Part 1 (dose escalation) is to determine a safe dose(s) of REGN5678 when it is given alone or in combination with cemiplimab. The goal of Part 2 (dose expansion) is to use the REGN5678 drug dose(s) found in Part 1 to see how well REGN5678 alone or in combination with cemiplimab works to shrink tumors. This study is looking at several other research questions, including: 1. Side effects that may be experienced by taking REGN5678 alone or in combination with cemiplimab 2. How REGN5678 alone or in combination with cemiplimab works in the body 3. How much REGN5678 and/or cemiplimab are present in the blood 4. To see if REGN5678 alone or in combination with cemiplimab works to reduce the size of the tumor by helping the immune system destroy the tumor
∙ mCRPC cohorts (men):
• Men with histologically or cytologically confirmed adenocarcinoma of the prostate without pure small cell carcinoma.
• PSA value at screening ≥4 ng/mL that has progressed within 6 months prior to screening as defined in the protocol.
• Has received ≥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 (eg, abiraterone, enzalutamide, apalutamide, or darolutamide)
⁃ 177Lu-PSMA-617 radiotherapy, or another lutetium-based PSMA targeted radioligand, as described in the protocol
∙ ccRCC cohorts (men and women):
• Histologically or cytologically confirmed RCC with a clear-cell component.
• Diagnosis of metastatic ccRCC with at least one measurable lesion via RECIST 1.1 criteria
• Has progressed on or after ≥1 line prior systemic therapy approved in the metastatic setting. Prior treatment must include an anti-Programmed Death-1 (receptor) \[PD-1\]/Programmed Death-Ligand 1 (PD-L1) therapy and either ipilimumab and/or a tyrosine kinase inhibitor