A Trial to Find Out if REGN5678 (Nezastomig) is Safe and How Well it Works Alone or in Combination With Cemiplimab for Adult Participants With Metastatic Castration-Resistant Prostate Cancer and Other Tumors

What this study is about

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

Who can join (things the study team will check)

✅ You may be able to join if…

• 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: ccRCC cohorts (men and women):
  • 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
• 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

🚫 You may not be able to join if…

• 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, as described in the protocol
• Has received any previous systemic biologic therapy within 5 half-lives of first dose of study therapy, as described in the protocol
• Has received prior PSMA-targeting therapy with the exception of a PSMA targeting radioligand (eg. 177Lu-PSMA-617) in mCRPC
• Dose Escalation: Has had prior anti-cancer immunotherapy (other than sipuleucel-T) within 5 half-lives prior to study therapy.
• Dose Expansion (mCRPC only): Has had prior anti-cancer immunotherapy, as described in the protocol
• 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
• Ongoing or recent (within 5 years) evidence of significant autoimmune disease that required treatment with systemic immunosuppressive treatments, as described in the protocol
• 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
• 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

Where this trial is running

• Banner MD Anderson Cancer Center, Gilbert, Arizona, United States
• Mayo Clinic, Phoenix, Arizona, United States
• University of Arizona, Tucson, Arizona, United States
• John Wayne Cancer Institute (JWCI), Santa Monica, California, United States
• Sarah Cannon Research Institute (SCRI), Denver, Colorado, United States
• Yale University Hospital, New Haven, Connecticut, United States
• Mayo Clinic Jacksonville, Jacksonville, Florida, United States
• Moffitt Cancer Center - McKinley Drive, Tampa, Florida, United States
• Massachusetts General Hospital, Boston, Massachusetts, United States
• Henry Ford Health, Detroit, Michigan, United States
• Mayo Clinic, Rochester, Minnesota, United States
• NYU Langone Health Perlmutter Cancer Center, New York, New York, United States

+ 12 more sites.

Who to contact

Clinical Trials Administrator · 844-734-6643 · clinicaltrials@regeneron.com

It's completely normal to call and ask questions before deciding anything. Mention the study ID: NCT03972657.