Pembrolizumab/Vibostolimab (MK-7684A) or Atezolizumab in Combination With Chemotherapy in First Line Treatment of Extensive-Stage Small Cell Lung Cancer (MK-7684A-008/KEYVIBE-008)

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.