Trial Purpose

The purpose of this study is to evaluate pathological complete response (pCR) rate of coformulated favezelimab/pembrolizumab (MK-4280A) or pembrolizumab as assessed by blinded central pathology review (BICR) in participants with cutaneous squamous cell carcinoma (cSCC) [Cohort A] and to evaluate lenvatinib in combination with coformulated favezelimab/pembrolizumab or pembrolizumab with respect to objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 as assessed by investigator in participants proficient in mismatch repair (pMMR) endometrial cancer (EC) [Cohort B].

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About The Trial

All patients who enroll in the trial will receive medication while on the study.

Cutaneous Squamous Cell Carcinoma (cSCC) Patients

50% will receive MK-4280A (contains favezelimab and pembrolizumab) before and after surgery.

50% will receive pembrolizumab before and after surgery.

Endometrial Cancer (EC) Patients

50% will receive MK-4280A (contains favezelimab and pembrolizumab) and lenvatinib.

50% will receive pembrolizumab and lenvatinib.

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Phase 2

Tests the medicine or vaccine in approximately 100 to 500 volunteers. In the case of medicines, volunteers usually have the disease or condition the investigational medicine is designed to treat. In vaccine studies, the volunteers are usually healthy.

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  • Actual study start date September 29, 2023
  • Estimated primary completion date March 9, 2027
  • Estimated study completion date March 9, 2027


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Cutaneous Squamous Cell Carcinoma, Endometrial Cancer, Solid Tumor

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Age Range

18 - No Age Maximum

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Trial locations