This study will evaluate the combination of a fixed dose pembrolizumab/vibostolimab co-formulation (MK-7684A) with etoposide/platinum chemotherapy followed by MK-7684A compared to the combination of atezolizumab with etoposide/platinum chemotherapy followed by atezolizumab in the first-line treatment of Extensive-Stage Small Cell Lung Cancer (ES-SCLC). The primary hypothesis is, with respect to overall survival, MK-7684A in combination with the background therapy of etoposide/platinum followed by MK-7684A, is superior to atezolizumab in combination with the background therapy of etoposide/platinum followed by atezolizumab.
With Amendment 4, the experimental Pembrolizumab/Vibostolimab arm (MK-7684A) was discontinued and all ongoing participants were offered an option to move to the comparator Atezolizumab monotherapy arm for the remainder of the study. There will be no further analyses of efficacy, and no European Organization for Research and Treatment of Cancer (EORTC)-Quality of Life Questionnaire-Core 30 (QLQ-C30) and Lung Cancer 13 module (EORTC QLQ-LC13) outcome measures will be reported. Effective as of Amendment 5, participants with access to approved standard of care (SOC) should be considered for discontinuation from the study. Those benefiting from atezolizumab, but unable to access it as SOC outside the study, may continue on study and receive treatment with atezolizumab until discontinuation criteria are met.
Pembrolizumab 200 mg plus vibostolimab 200 mg fixed dose coformulation administered via IV infusion Q3W on Day 1 of each cycle until discontinuation criteria are met.
Saline solution administered via IV infusion on Cycle 1 (and Q3W as needed beyond Cycle 1)
Etoposide 100 mg/m\^2 administered via IV infusion Q3W on Days 1 2, 3 of each cycle for up to 4 cycles
Cisplatin 75 mg/m\^2 administered via IV infusion Q3W on Day 1 of each cycle for up to 4 cycles.
Atezolizumab 1200 mg administered via IV infusion Q3W on Day 1 of each cycle until discontinuation criteria are met.
Carboplatin AUC 5 mg/mL/min administered via IV infusion Q3W on Day 1 of each cycle for up to 4 cycles.
Ciudad Autonoma de Buenos Aires, Buenos Aires, Argentina
Mar del Plata, Buenos Aires, Argentina
Buenos Aires, Buenos Aires F.D., Argentina
Rosario, Santa Fe Province, Argentina
Rosario, Santa Fe Province, Argentina