Relay Therapeutics reported a Phase 2 efficacy signal for zovegalisib (RLY-2608) in patients with PIK3CA-driven vascular anomalies, reporting a 60% volumetric response. The company framed the result as more than double what was expected, expanding the PI3Kα inhibitor’s development prospects beyond breast cancer combinations. Relay’s zovegalisib is an isoform-selective PI3Kα inhibitor being studied in late-stage clinical trials for PIK3CA-mutated settings, including HR+/HER2- advanced breast cancer. Vascular anomalies are presented as a separate indication where few targeted options exist. The update increases attention on PI3Kα pathway dependence in the rare vascular disorder group and may influence future trial design and commercialization assumptions for the program.