Study of Favezelimab (MK-4280) as Monotherapy and in Combination With Pembrolizumab (MK-3475) With or Without Chemotherapy or Lenvatinib (MK-7902) AND Favezelimab/Pembrolizumab (MK-4280A) as Monotherapy in Adults With Advanced Solid Tumors (MK-4280-001)

This is a safety and pharmacokinetics study of favezelimab as monotherapy and in combination with pembrolizumab AND favezelimab/pembrolizumab as monotherapy in adults with metastatic solid tumors for which there is no available therapy which may convey clinical benefit. Part A of this study is a dose escalation design in which participants receive favezelimab as monotherapy or favezelimab in combination with pembrolizumab. Part B is a dose confirmation design to estimate the recommended Phase 2 dose (RP2D), as determined by dose-limiting toxicity, for favezelimab in combination with pembrolizumab or pembrolizumab and lenvatinib in participants with advanced solid tumors. Part B will also assess the efficacy of favezelimab as monotherapy; favezelimab in combination with pembrolizumab with and without chemotherapy; favezelimab in combination with pembrolizumab and lenvatinib; and favezelimab/pembrolizumab as monotherapy in expansion cohorts. Participants who have completed the initial course of treatment and have investigator-determined progressive disease may be eligible for a second course of an additional 17 cycles of study treatment.