Merck and Kelun-Biotech’s sacituzumab tirumotecan (sac-TMT) scored a first randomized Phase 3 win in treatment-naïve, PD-L1-positive non-small cell lung cancer, cutting the risk of disease progression or death by 65% versus Keytruda alone in an interim analysis. The OptiTROP-Lung05 abstract presented at ASCO 2026 showed median PFS was not reached in the combination arm after 10.5 months of follow-up versus 5.7 months for Keytruda. Merck’s Keytruda remains the backbone, but the effect size escalation in an ADC-Checkpoint combo is likely to intensify competition against PD-(L)1xVEGF bispecifics in first-line settings. While key overall survival data were not mature at the Sept. 29, 2025 cutoff, investigators noted a preliminary 45% OS improvement trend favoring the combination. The dataset is expected to feed later, fully mature PFS analyses and eventual regulatory conversations for an area that has become one of the most consequential oncology adoption battlegrounds worldwide.