Study of Favezelimab Coformulated With Pembrolizumab (MK-4280A) in Participants With Selected Solid Tumors (MK-4280A-010)

Inclusion Criteria

• •Cohort A only
• •Histologically confirmed diagnosis of resectable cutaneous squamous cell carcinoma (cSCC) as the primary site of malignancy (metastatic skin involvement from another primary cancer or from an unknown primary cancer is not permitted)
• •Stage II to Stage IV disease without distant metastasis (M1). cSCC tumors arising in the head and neck will be staged according to American Joint Committee on Cancer (AJCC) Edition (Ed.) 8 and cSCC tumors arising in non-head and neck locations will be staged according to Union for International Cancer Control (UICC) Ed. 8
• •Is systemic treatment naïve
• •Archival tumor tissue sample, or newly obtained surgical resection, or biopsy sample of a tumor lesion not previously irradiated has been provided
• •Is an individual of any sex/gender, at least 18 years of age at the time of providing the informed consent
• •Cohort B only
• •Histologically confirmed diagnosis of endometrial cancer (EC) that is not deficient in mismatch repair (dMMR) proficient in mismatch repair (pMMR) as documented by a local test report
• •Documented evidence of stage IVB (per 2009 International Federation of Gynecology and Obstetrics (FIGO) staging), recurrent, or metastatic EC, and are not candidates for curative surgery or radiation
• •Has radiographic evidence of disease progression after 1 prior systemic, platinum-based chemotherapy regimen for EC in any setting
• •Measurable disease per Response Evaluation Criteria In Solid Tumors (RECIST 1.1) by investigator (before first dose of study intervention)
• •Is assigned female sex at birth, at least 18 years of age at the time of providing the informed consent
• •Has adequately controlled blood pressure without antihypertensive medication
• •All Cohorts
• •Agrees to follow contraception guidelines if a participant of childbearing potential
• •Has a life expectancy \>3 years per investigator assessment
• •Has adequate organ function
• •Has Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• •If positive for hepatitis B, has received antiviral therapy for ≥4 weeks and undetectable viral load prior to randomization
• •If positive for hepatitis C, has undetectable viral load at screening
• •If positive for human immunodeficiency virus (HIV), has well-controlled HIV on a stable highly active antiretroviral therapy