Sonesitatug vedotin, a claudin 18.2-targeting antibody-drug conjugate (ADC), showed a statistically meaningful overall survival improvement in Phase 3 CLARITY-Gastric01. Presented at the ESMO Congress 2026, the third-line-or-later subgroup saw median OS double to 10.0 months versus 5.0 months with investigator’s choice. The ADC did not significantly improve progression-free survival in the overall population, with the report noting the differing outcomes across endpoints. The trial enrolled 532 patients with unresectable locally advanced or metastatic CLDN18.2-positive gastroesophageal cancer defined by membranous staining in at least 25% of tumor cells. For treatment planning, the split between OS and PFS may shape how clinicians and regulators interpret patient selection, dosing strategy, and line-of-therapy placement for future decisions on ADC adoption in CLDN18.2-positive disease.