Study of Vibostolimab Alone and in Combination With Pembrolizumab in Advanced Solid Tumors

This is a safety, efficacy, and pharmacokinetics (PK) study of vibostolimab (MK-7684) as monotherapy and in combination with pembrolizumab (MK-3475) or pembrolizumab plus pemetrexed and carboplatin in adults with metastatic solid tumors for which there is no available therapy that is expected to convey clinical benefit. Part A of this study is a dose escalation and confirmation phase to estimate the recommended Phase 2 dose (RPTD) for vibostolimab monotherapy or in combination with pembrolizumab, pemetrexed, and carboplatin. Part A will also evaluate the anti-tumor activity of vibostolimab in combination with pembrolizumab plus pemetrexed and carboplatin in participants with non-small cell lung cancer (NSCLC) and vibostolimab (at two dose levels) in combination with pembrolizumab in Japanese participants with gastric cancer. Part B will evaluate the anti-tumor activity of vibostolimab at the RPTD when used as monotherapy and in combination with pembrolizumab in participants with advanced solid tumors in a non-randomized study design. Part B will also evaluate 2 doses of vibostolimab in combination with pembrolizumab in participants with programmed death 1 (PD-1) treatment naïve cancer using a 1:1 randomized study design. Part B is expanded with Amendment 11 to include an additional arm that will compare the safety and PK of a fixed dose of pembrolizumab/vibostolimab coformulation (MK-7684A) to vibostolimab in combination with pembrolizumab administered as separate intravenous infusions. Part A is expanded with Amendment 12 to include an additional arm that will compare the safety and PK of vibostolimab plus pembrolizumab plus the investigator’s choice of platinum agent (carboplatin or cisplatin), and etoposide. Part B is expanded with Amendment 12 to include evaluation of efficacy of vibostolimab plus pembrolizumab plus the investigator’s choice of platinum agent (carboplatin or cisplatin), and etoposide and efficacy of pembrolizumab/vibostolimab coformulation in participants from mainland China. The primary hypotheses are that vibostolimab administered as monotherapy or in combination with pembrolizumab is safe and tolerable when administered at the RPTD and that pembrolizumab/vibostolimab coformulation is safe and tolerable when administered as a fixed dose.