A Trial to Find Out How Safe REGN7075 is and How Well it Works in Combination With Cemiplimab for Adult Participants With Advanced Cancers

A Phase 1/2 Study of REGN7075 (EGFRxCD28 Costimulatory Bispecific Antibody) in Combination With Cemiplimab in Patients With Advanced Solid Tumors

This study is researching an investigational drug called marlotamig (REGN7075) by itself and in combination with cemiplimab with or without chemotherapy. The study is focused on patients with certain solid tumors that are in an advanced stage.

The aim of the study is to see how safe and tolerable marlotamig is by itself and in combination with cemiplimab (with or without chemotherapy), and to find out what is the best dose of marlotamig to be given to patients with advanced solid tumors when combined with cemiplimab (with or without chemotherapy). Another aim of the study is to see how effective marlotamig by itself, or in combination with cemiplimab (with or without chemotherapy), is at treating cancer patients.

The study is also looking at:

• Side effects that may be experienced by people taking marlotamig by itself and in combination with cemiplimab with or without chemotherapy
• How marlotamig works in the body by itself and in combination with cemiplimab with or without chemotherapy
• How much marlotamig is present in the blood when given by itself and in combination with cemiplimab with or without chemotherapy
• To see if marlotamig by itself and in combination with cemiplimab with or without chemotherapy works to treat cancer by controlling the proliferation of tumor cells to shrink the tumor
• Whether the body makes antibodies against the study drugs (marlotamig and cemiplimab) (which could make the drug less effective or could lead to side effects)

Key Inclusion Criteria:

1. Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
2. Has histologically or cytologically confirmed cancer that meets criteria as defined in the protocol
3. Expansion Cohorts only: Is anti-Programmed cell Death protein-1 (PD-1)/Programmed cell Death Ligand-1 (PD-L1) naïve, defined as never having previously been treated with a drug that targets the PD-1
4. Has at least 1 lesion that meets study criteria as defined in the protocol
5. Willing to provide tumor tissue from newly obtained biopsy (at a minimum core biopsy) from a tumor site that has not been previously irradiated
6. Has adequate organ and bone marrow function as defined in the protocol
7. In the judgement of the investigator, has a life expectancy of at least 3 months

Key Exclusion Criteria:

1. Is currently participating in another study of a therapeutic agent
2. Has participated in any study of an investigational agent or an investigational device within 4 weeks of the first administration of study drug as defined in the protocol
3. Has received treatment with an approved systemic therapy within 4 weeks of the first administration of study drug or has not yet recovered (ie, grade 1 or baseline) from any acute toxicities
4. Has received recent anti-Epidermal Growth Factor Receptor (EGFR) antibody therapy as defined in the protocol
5. Has received radiation therapy or major surgery within 14 days of the first administration of study drug or has not recovered (ie, grade 1 or baseline) from adverse events
6. Has received any previous systemic, non-immunomodulatory biologic therapy within 4 weeks of first administration of study drug.
7. Has had prior anti-cancer immunotherapy within 5 half-lives prior to study drug as defined in the protocol
8. Has second malignancy that is progressing or requires active treatment as defined in the protocol
9. Has any condition requiring ongoing/continuous corticosteroid therapy (>10 mg prednisone/day or anti-inflammatory equivalent) within 1-2 weeks prior to the first dose of study drug as defined in the protocol
10. Has ongoing or recent (within 5 years) evidence of significant autoimmune disease or any other condition that required treatment with systemic immunosuppressive treatments as defined in the protocol
11. Has untreated or active primary brain tumor, Central Nervous System (CNS) metastases, leptomeningeal disease, or spinal cord compression
12. Has encephalitis, meningitis, organic brain disease (eg, Parkinson's disease) or uncontrolled seizures within 1 year prior to the first dose of study drug
13. Has any ongoing inflammatory skin disease as defined in the protocol

NOTE: Other protocol-defined Inclusion/ Exclusion Criteria apply