Pfizer’s first new antibody-drug conjugate (ADC) to report pivotal Phase 3 results after the Seagen acquisition missed its primary endpoint in non-small-cell lung cancer. The ADC, sigvotatug vedotin (also known as SV), did not show statistical significance for overall survival versus docetaxel in the overall population. Pfizer said the trial still showed manageable safety and pointed to subgroup signals, including a stronger trend among patients who received only one prior line of systemic therapy. The outcome adds pressure on the company’s ADC strategy at a time when the market is scrutinizing which mechanisms translate into durable efficacy. Pfizer is described as continuing development based on subgroup outcomes, phase I signals, and an ongoing Phase 3 Keytruda combination effort. The result is a reminder that even late-stage readouts with recognizable biology can fail to clear primary OS hurdles, affecting future asset prioritization and deal expectations across the sector.