In early-stage non-small cell lung cancer (eNSCLC), immune checkpoint inhibitor (ICI) monotherapy without chemotherapy remains investigational and unapproved. Phase 2 neoadjuvant IO only trials established key early response markers (major pathologic regression, pathologic complete response, and objective response rate), clarifying the contributions of ICI monotherapy and CT-ICI. CT-ICI showed superior pathologic outcomes and became the preferred strategy in phase 3 trials. While pCR is a useful early efficacy marker, FDA approval still requires long-term outcomes such as event-free or overall survival. ICI monotherapy appears safe and well tolerated. Chemotherapy-free dual ICI regimens remain investigational.