A Study to Investigate the Efficacy of Durvalumab Plus Tremelimumab in Combination With Chemotherapy Compared With Pembrolizumab in Combination With Chemotherapy in Metastatic NSCLC Patients With Non-squamous Histology Who Have Mutations and/or Co-mutations in STK11, KEAP1, or KRAS

The purpose of the study is to assess the efficacy of durvalumab plus tremelimumab in combination with chemotherapy compared with pembrolizumab in combination with chemotherapy in metastatic NSCLC patients with non-squamous histology who have mutations and/or co-mutations in STK11, KEAP1, or KRAS.

A trial to learn if durvalumab plus tremelimumab with chemotherapy is safe and how well it works compared to pembrolizumab with chemotherapy in participants with metastatic non-small cell lung cancer with certain genetic mutations. INFORMATION FOR TRIAL PARTICIPANTS: Researchers are looking for a better way to treat people who have metastatic NSCLC and tumors with STK11, KEAP1, or KRAS genetic mutations. Most people learn they have NSCLC after it has already become metastatic, and it can no longer be treated with surgery. Based on previous trials, researchers think durvalumab plus tremelimumab with chemotherapy could help participants more than the current standard treatment, which is pembrolizumab with chemotherapy. Durvalumab and tremelimumab are designed to work by helping the immune system recognize and kill cancer cells. In this trial, researchers want to learn more about how well durvalumab plus tremelimumab with chemotherapy works in people with metastatic NSCLC and genetic mutations that can cause the cancer to be less responsive to treatment. This trial is planned to have 280 participants. These participants will be randomly divided into one of two groups: * One group will receive durvalumab plus tremelimumab with standard of care chemotherapy * One group will receive pembrolizumab with standard of care chemotherapy Durvalumab, tremelimumab, pembrolizumab, and chemotherapy are given as an injection over time into a vein, also called an IV infusion. Chemotherapy will be one of the following regimens: pemetrexed plus cisplatin or pemetrexed plus carboplatin. This is an open-label trial. This means that each participant will know which trial treatment they receive, and the doctors and trial staff will also know. Researchers will measure and compare: * How long participants live during the trial * How long participants live during the trial without their cancer getting worse * How many participants' tumors respond to treatment * How long participants' tumor responses last * How long before participants need to start a different treatment type Researchers will also keep track of all the medical problems participants have during the trial and monitor their safety. Participants will stop receiving trial treatment if they no longer benefit from it or they stop participating for another reason. Participants will visit their trial site every 3 to 4 weeks. At most visits, participants will: * Have a physical exam and answer questions about any medications they are taking or any medical problems they have * Receive their trial treatment * Give blood and urine samples * Have pictures of their tumors taken using CT or MRI scans