Relay Therapeutics Inc. (NASDAQ: RLAY) announced initial clinical data from its Phase 2 ReInspire trial showing that zovegalisib demonstrated a 60% volumetric response rate in patients with PIK3CA-driven vascular anomalies.

The study evaluated 32 patients aged 12 and older across three dose levels of zovegalisib. Of 20 patients assessed for efficacy at 12 weeks, 60% achieved a volumetric response, defined as a 20% or greater reduction in target lesion volume from baseline. All responses occurred at the first MRI scan at 12 weeks.

The Cambridge, Massachusetts-based company reported that 89% of patients showed clinical improvement according to investigator assessments, while 79% demonstrated improvement based on patient-reported outcomes at week 12. All 32 patients remained on treatment as of the April 15, 2026 data cutoff date.

Safety data showed that among 22 patients treated at the two lower doses (100mg and 300mg twice daily), 23% required dose reductions but no patients discontinued treatment due to adverse events. Only two patients experienced Grade 3 or higher treatment-related adverse events.

The company has opened expansion cohorts at 400mg once daily and 300mg twice daily doses. Vascular anomalies are rare disorders affecting blood vessel and lymphatic vessel development, with an estimated 170,000 patients in the United States living with PIK3CA-driven forms of the condition.

Zovegalisib is designed as a mutant-selective PI3Kα inhibitor, targeting mutations in the PIK3CA gene that drive certain cancers and vascular anomalies. The drug is also being evaluated in a Phase 3 trial for metastatic breast cancer.

The data were presented at the International Society for the Study of Vascular Anomalies World Congress 2026 in Philadelphia, according to the company's press release.