A Study of Pembrolizumab (MK-3475) With or Without Maintenance Olaparib in First-line Metastatic Squamous Non-small Cell Lung Cancer (NSCLC, MK-7339-008/KEYLYNK-008)

This study has 2 phases: an Induction Phase (4 Cycles) and a Maintenance Phase (Up to 31 cycles of pembrolizumab). In the Induction Phase, participants receive pembrolizumab plus carboplatin plus a taxane (paclitaxel or nab-paclitaxel). In the Maintenance Phase, participants with a partial or complete disease response or with stable disease after completing four cycles of induction therapy and who meet eligibility criteria will be randomly assigned to receive pembrolizumab plus maintenance olaparib OR pembrolizumab plus maintenance olaparib placebo. In the Maintenance Phase, participants randomly assigned to receive pembrolizumab for up to 31 cycles plus maintenance olaparib OR maintenance olaparib placebo until centrally verified progressive disease (PD), intolerable toxicities, or physician decision. As of Amendment 07, participants actively taking placebo will discontinue taking the placebo intervention and continue in the study.