Relay presses ahead on PI3Kα inhibitor after first phase 2 data in vascular (blood vessel) disorder

Relay Therapeutics has reported its first phase 2 readout for the PI3Kα inhibitor zovegalisib (RLY-2608) in patients with PIK3CA-driven vascular anomalies (a group of rare blood vessel disorders), demonstrating a 60% volumetric response rate at 12 weeks and 95% of patients showing some lesion reduction, with a favorable safety profile allowing chronic dosing.

Based on these data, Relay is moving "full steam ahead" with zovegalisib in both vascular anomalies and breast cancer, maintaining a dual indication strategy and advancing a phase 3 trial in HR+/HER2- advanced breast cancer while continuing the vascular anomalies phase 2 study with a once-daily 400 mg dose instead of the twice‑daily 400 mg dose that was discontinued due to suboptimal safety.

The company views zovegalisib as having the potential to meaningfully change the treatment paradigm for this underserved vascular‑anomaly population, estimating around 170,000 affected patients in the U.S., and plans further clinical data disclosure at the 2026 ISSVA World Congress in Philadelphia.