A Phase 3 trial testing an antibody-drug combination regimen in first-line PD-L1-high metastatic lung cancer reported a negative outcome. Sacituzumab govitecan plus pembrolizumab failed to produce a statistically significant improvement in progression-free survival compared with the control arm, according to the trial results. For clinicians and development teams, the readout is a clear signal that the approach did not translate prior cross-tumor ADC activity into improved outcomes in this biomarker-defined lung cancer setting. The setback also sharpens the competitive landscape for next-line ADC–checkpoint combinations, where future programs will likely place greater emphasis on upfront enrichment, response predictors, and safety/tolerability tradeoffs.