Sacituzumab tirumotecan and pembrolizumab are drugs being tested for lung cancer treatment. This study compares the two drugs together versus pembrolizumab alone to see which is better at helping patients live longer. **Pembrolizumab** is a medicine that helps the immune system fight cancer, while **sacituzumab tirumotecan** is a new drug being tested. The study is for people with a type of lung cancer called non-small cell lung cancer (NSCLC) who have a tumor score that shows they might respond well to these treatments. People in the study may receive pembrolizumab alone if their cancer worsens after the first part of the study. The study requires participants to have a certain health status and does not allow those with other serious health issues or who have had specific treatments before.

• Participants may receive up to 9 extra cycles of pembrolizumab if needed.
• Participants must have a life expectancy of at least 3 months.
• Certain previous treatments or health conditions may exclude participation.