This clinical trial is focused on studying a type of lung cancer known as Non-Small Cell Lung Cancer (NSCLC). The study involves participants who have undergone surgery to remove the cancer and have received chemotherapy afterward. The trial is testing the effectiveness and safety of a combination of two medications, Tiragolumab and Atezolizumab, compared to a combination of a placebo and Atezolizumab. Tiragolumab and Atezolizumab are given as infusions, which means they are administered directly into the bloodstream through a vein.

The purpose of the study is to evaluate how well the combination of Tiragolumab and Atezolizumab works in preventing the return of cancer in patients whose tumors have a specific protein called PD-L1. The study will also look at the safety of these medications and how they affect the quality of life of the participants. Participants will receive the treatment over a period of up to 12 months, and their health will be monitored regularly to assess the effects of the treatment.

Throughout the study, researchers will collect information on how long participants remain free of cancer, any side effects they experience, and their overall survival. The study will also measure the levels of Tiragolumab and Atezolizumab in the blood at different times to understand how the body processes these medications. This trial aims to provide valuable insights into the potential benefits of combining Tiragolumab with Atezolizumab for treating NSCLC.