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Promising initial efficacy data with 60% volumetric response rate across doses and 29%* at the lowest tested dose of 100mg twice daily (BID) with all patients ongoing
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Interim investigator- and patient-reported outcomes show 89% and 79% of patients achieved clinical improvement at week 12, respectively, and support the potential of zovegalisib to drive clinically meaningful benefit for patients
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Evaluation across a wide dose range confirms potential therapeutic window, with interim safety profile supportive of chronic dosing and no patients discontinuing treatment due to adverse events
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Expansion cohorts for adults and adolescents opened at 400mg once daily (QD) and 300mg BID;
pediatric dose-finding is ongoing -
Company to host conference call today, Tuesday, May 19, 2026 at 8:00 am ET
CAMBRIDGE, Mass., May 19, 2026 (GLOBE NEWSWIRE) -- Relay Therapeutics, Inc. (Nasdaq: RLAY), a clinical-stage, small molecule precision medicine company developing potentially life-changing therapies for patients living with cancer and genetic disease, today announced initial clinical data from the Phase 2 ReInspire trial of zovegalisib in vascular anomalies signaling the advantage of PI3Kα mutant-selective inhibition. Vascular anomalies are a group of rare disorders characterized by abnormal development of blood vessels, lymphatic vessels and surrounding tissues. As of the April 15, 2026 data cut-off date, in the Part 1 dose randomization portion of the study for adults and adolescents ages 12 and up, 60% of patients achieved a volumetric response at the earliest time point (12 weeks) and nearly all patients experienced symptomatic improvement at 12 weeks while maintaining a safety and tolerability profile showing the potential for chronic use. The data are being presented at the International Society for the Study of Vascular Anomalies (ISSVA) World Congress 2026, taking place in Philadelphia.
“These data demonstrate, for the first time, the promise of PI3Kα mutant-selective inhibition for patients with vascular anomalies,” said Don Bergstrom, M.D., Ph.D., President of R&D at Relay Therapeutics. “The combination of robust volumetric responses, symptomatic improvement, and a safety profile that supports chronic dosing underscores the potential of zovegalisib to meaningfully change the treatment paradigm for this underserved population. These early results strengthen our conviction in zovegalisib’s differentiated profile and its potential ability to deliver lasting benefit for patients and families affected by vascular anomalies.”
ReInspire – Zovegalisib Study in PIK3CA-Driven Vascular Anomalies
Zovegalisib is currently being evaluated in an ongoing Phase 2 study designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and efficacy of zovegalisib in adults and children with vascular anomalies driven by PIK3CA mutations.
The study consists of three age groups: Group 1 is adults and adolescents 12 years or older, Group 2 is pediatrics 6-11 years old, and Group 3 is pediatrics 2-5 years old. For each age group, there is a 3-part design: Part 1 is dose selection, Part 2 is dose expansion featuring open-label basket design with exploratory single-arm dose cohorts across various patient subpopulations, and Part 3 is potentially a randomized study.
The data reported today are from Part 1 of the study in the adults and adolescents cohort (patients 12 years or older), which featured randomized dose selection across three doses. As of the April 15, 2026 data cut-off date, 32 total patients were enrolled and randomized to the following dose cohorts: N=11 at 100mg BID, N=11 at 300mg BID, and N=10 at 400mg BID. Of the patients enrolled, 22 had PIK3CA-related overgrowth spectrum (PROS), 8 had a lymphatic malformation (LM), and 2 had a venous malformation (VeM). 23 patients (72%) had prior treatment with sirolimus and/or alpelisib, which was allowed in the study.
Expansion cohorts (Part 2) for 12 and older patients have been opened at 400mg once daily (QD) and 300mg BID and are enrolling.
Unless indicated otherwise, all data reported are as of the April 15, 2026 data cut-off date.
Initial Efficacy Data Demonstrated Meaningful Volumetric Lesion Regression
Of the 32 patients enrolled, 20 have been evaluated for efficacy per volumetric response assessment by blinded independent central review (BICR), which is assessed by MRI every 12 weeks. The remaining 12 patients had not reached the 12-week timepoint. A response is defined by a 20% or greater reduction in target lesion(s) volume from baseline.
Of the 20 response-evaluable patients, 15 had PROS, 4 had a LM, and 1 had a VeM. Of patients with a confirmed PIK3CA mutation, 25% of patients had a kinase mutation and 55% had a non-kinase mutation, while 20% had no PIK3CA mutation documented at the time of data cut-off. 65% had been previously treated with alpelisib or sirolimus (35% had been treated by both). All 32 patients remained on treatment as of the data cut-off date.
About Vascular Anomalies
Vascular anomalies (VAs) are a group of rare disorders characterized by abnormal development of blood vessels, lymphatic vessels and surrounding tissues. These conditions can vary widely in presentation and severity and may cause chronic pain, swelling, disfigurement, impaired mobility, bleeding and other serious complications that can significantly impact quality of life. PIK3CA-driven vascular anomalies are a subset of these disorders caused by mutations in the PIK3CA gene, including conditions such as PIK3CA-related overgrowth spectrum, lymphatic malformations and venous malformations. Approximately 170,000 patients in the U.S. are estimated to be living with PIK3CA-driven vascular anomalies. Current systemic treatment options are limited and may be associated with tolerability challenges that can restrict long-term use.
About Zovegalisib
Zovegalisib is the lead investigational program in Relay Therapeutics’ efforts to discover and develop mutant-selective inhibitors of PI3Kα, the most frequently mutated kinase in all cancers and all vascular anomalies. Zovegalisib has the potential, if approved, to address a significant portion of the approximately 140,000 patients with HR+/HER2- breast cancer with a PI3Kα mutation and the estimated 170,000 patients with vascular anomalies driven by a PI3Kα mutation per year in the United States, one of the largest patient populations for a precision medicine.
Traditionally, the development of PI3Kα inhibitors has focused on the active, or orthosteric, site. The therapeutic index of orthosteric inhibitors is limited by the lack of clinically meaningful selectivity for mutant versus wild-type (WT) PI3Kα and off-isoform activity. Toxicity related to inhibition of WT PI3Kα and other PI3K isoforms results in sub-optimal inhibition of mutant PI3Kα with reductions in dose intensity and frequent discontinuation. The Dynamo® platform enabled the discovery of zovegalisib, the first known allosteric, pan-mutant, and isoform-selective PI3Kα inhibitor, designed to overcome these limitations. Relay Therapeutics solved the full-length cryo-EM structure of PI3Kα, performed computational long time-scale molecular dynamic simulations to elucidate conformational differences between WT and mutant PI3Kα, and leveraged these insights to support the design of zovegalisib. Zovegalisib is currently being evaluated in multiple metastatic breast cancer studies and a first-in-human study designed to treat patients with PIK3CA mutation driven vascular anomalies.
About Relay Therapeutics
Relay Therapeutics (Nasdaq: RLAY) is a clinical-stage, small molecule precision medicine company developing potentially life-changing therapies for patients living with cancer and genetic disease. Relay Therapeutics’ Dynamo® platform integrates an array of leading-edge computational and experimental approaches designed to drug protein targets that have previously been intractable or inadequately addressed. The company’s lead clinical asset, zovegalisib, is the first pan-mutant selective PI3Kα inhibitor to enter clinical development and is currently in a Phase 3 clinical trial (ReDiscover-2) in HR+/HER2- metastatic breast cancer. Zovegalisib is also being investigated in a group of genetic disease indications called PIK3CA-driven vascular anomalies. Relay Therapeutics’ pipeline also includes programs for NRAS-driven solid tumors and Fabry disease.