This study investigates the effectiveness of an investigational medication compared to a placebo in treating patients with stage IB-IIIA non-small cell lung cancer (NSCLC) that has been completely removed by surgery. Non-small cell lung cancer is a type of lung cancer that grows and spreads more slowly than small cell lung cancer. The study focuses on patients whose cancer has specific changes in the epidermal growth factor receptor (EGFR) gene, which can affect how cancer cells grow and divide.

Participants in this study will be randomly assigned to receive either the investigational medication or a placebo. A placebo is an inactive substance that looks like the investigational medicine but does not contain any medicine. The study will evaluate if taking the investigational medication after surgery and standard treatments can improve overall survival compared to taking a placebo.

• Who can participate: Adults who have had surgery to completely remove stage IB-IIIA non-small cell lung cancer with certain EGFR mutations can participate. Participants must have a good performance status and have recovered from surgery and any required post-operative therapy. Specifically, participants must have an EGFR exon 19 deletion or L858R mutation.
• Study details: Participants will be randomly assigned to receive either the investigational medication or a placebo.