Study to Evaluate Adverse Events, Optimal Dose, and Change in Disease Activity, With Livmoniplimab in Combination With Budigalimab Plus Chemotherapy Versus IV Infused Pembrolizumab Plus Chemotherapy in Adult Participants With Untreated Metastatic Non-Squamous Non-Small Cell Lung Cancer (NSCLC)

Non-Squamous Non-Small Cell Lung Cancer (NSCLC) remains a leading cause of cancer mortality worldwide, with poor survival prospects for metastatic disease. The purpose of this study is to evaluate the optimized dose, adverse events, and efficacy of livmoniplimab in combination with budigalimab plus chemotherapy versus pembrolizumab plus chemotherapy in participants with untreated metastatic non-squamous non-small cell lung cancer. Livmoniplimab is an investigational drug being developed for the treatment of NSCLC. There are 2 stages to this study. In Stage 1, there are 4 treatment arms. Participants will either receive livmoniplimab (at different doses) in combination with budigalimab (another investigational drug) + chemotherapy, budigalimab +chemotherapy, or pembrolizumab +chemotherapy. In Stage 2, there are 2 treatments arms. Participants will either receive livmoniplimab (optimized dose) in combination with budigalimab +chemotherapy or placebo in combination with pembrolizumab +chemotherapy. Chemotherapy consists of IV Infused pemetrexed + IV infused cisplatin or IV infused or injected carboplatin. Approximately 840 adult participants will be enrolled in the study across 200 sites worldwide. Stage 1: In cohort 1, participants will receive intravenously (IV) infused livmoniplimab (dose A)+ IV infused budigalimab, + chemotherapy for 4 cycles followed by livmoniplimab + budigalimab + IV Infused pemetrexed. In cohort 2, participants will receive livmoniplimab (dose B) + budigalimab + chemotherapy for 4 cycles followed by livmoniplimab + budigalimab + pemetrexed. In cohort 3, participants will receive budigalimab + chemotherapy for 4 cycles followed by budigalimab + pemetrexed . In cohort 4, participants will receive IV Infused pembrolizumab + chemotherapy for 4 cycles followed by pembrolizumab + pemetrexed. Stage 2: In arm 1, participants will receive livmoniplimab (dose optimized) + budigalimab + chemotherapy for 4 cycles followed by livmoniplimab + budigalimab + pemetrexed. In arm 2, participants will receive IV Infused placebo + pembrolizumab + chemotherapy for 4 cycles followed by pembrolizumab + pemetrexed. The estimated study duration is 55 months. There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at a hospital or clinic and may require frequent medical assessments, blood tests, questionnaires, and scans.