This study is for adults with a type of lung cancer called Stage III Unresectable NSCLC. This means the cancer is locally advanced and cannot be removed by surgery. The study will test two medications, Durvalumab and Domvanalimab, given after patients have had a treatment called chemoradiation (using chemicals and radiation to kill cancer cells).

The study will compare how well these medications work when given together or with a placebo (a "fake" treatment). To join, patients should be 18 or older, have a certain type of lung cancer, and not have gotten worse after chemoradiation. They also need to have good health overall. Some people can't join if they have other serious illnesses or have had other types of cancer recently.

• Duration: Participation involves multiple visits over several months.
• Compensation: Participants may receive compensation for their time and travel.
• Risks: Potential side effects from medications and treatments.