Testing the Timing of Pembrolizumab Alone or With Chemotherapy as First Line Treatment and Maintenance in Non-small Cell Lung Cancer

This phase III trial studies whether pembrolizumab alone as a first-line treatment, followed by pemetrexed and carboplatin with or without pembrolizumab after disease progression is superior to induction with pembrolizumab, pemetrexed and carboplatin followed by pembrolizumab and pemetrexed maintenance in treating patients with stage IV non-squamous non-small cell lung cancer. Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Drugs used in chemotherapy, such as pemetrexed and carboplatin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. It is not yet known whether giving first-line pembrolizumab followed by pemetrexed and carboplatin with or without pembrolizumab works better in treating patients with non-squamous non-small cell cancer.