Relay Therapeutics' Zovegalisib Shows 60% Early Response Rate in Rare Vascular Anomaly Trial
Initial Data Highlights: 60% Volumetric Response and Strong Safety Profile
Relay Therapeutics (NASDAQ: RLAY) announced initial Phase 2 clinical results for its lead drug candidate zovegalisib, targeting PIK3CA-driven vascular anomalies—a group of rare conditions marked by abnormal blood vessel growth. As of April 15, 2026, 60% of the first 20 response-evaluable patients experienced 20% or greater lesion shrinkage by MRI at 12 weeks. Importantly, no patients discontinued therapy due to side effects, positioning zovegalisib as a potential chronic treatment option for an underserved population.
Clinical Benefit Confirmed Across Doses and Patient Histories
The Part 1 portion of the trial enrolled 32 patients ages 12 and older, randomized across three dose cohorts:
| Dose Cohort | Patients | Volumetric Response Rate |
|---|---|---|
| 100mg BID | 11 | 43% (3/7)* |
| 300mg BID | 11 | 62% (8/13) |
| 400mg BID | 10 | -- |
| Total across doses | 32 | 65% (13/20) |
*One additional unconfirmed responder after the main data cutoff.
Notably, 95% of patients showed at least some reduction in lesion size. Clinical improvements were reported by 89% of clinicians and 79% of patients at week 12, reinforcing the value of the measured radiological outcomes.
Supportive Safety and Tolerability Data: No Discontinuations Due to Adverse Events
Zovegalisib's safety results add to the promising efficacy signals. At the 100mg and 300mg BID dosing levels (22 patients), there were no safety-related discontinuations and dose reductions were needed in just 23% of cases. Only 2 patients (9%) had more severe (Grade 3 or above) side effects. Known issues from traditional PI3Ka inhibitors—such as rash, severe hyperglycemia, and diarrhea—were not observed at higher grades, and no patients required prophylactic treatment.
The highest dose (400mg BID) did show increased adverse events and is being deprioritized for this population in favor of 400mg QD and 300mg BID, both now enrolling in expansion cohorts.
Zovegalisib Could Reshape Treatment for Rare Vascular Disorders
Current systemic therapies for PIK3CA-driven vascular anomalies are limited and often result in intolerable side effects. Zovegalisib is the first allosteric, pan-mutant, isoform-selective PI3Ka inhibitor to reach clinical trials for these disorders. This selectivity is designed to maximize efficacy while minimizing unwanted toxicity linked to wild-type inhibition.
- Participants had advanced disease: 72% had prior treatment with sirolimus or alpelisib.
- Quick responses seen: All volumetric responses observed at the first (12-week) MRI.
- Durable benefit: Four responders had confirmed and deepening benefit at 24 weeks.
What’s Next? Ongoing Expansion Cohorts and Upcoming Data
Enrollment continues in the expansion cohorts (adults/adolescents) at 400mg QD and 300mg BID. Pediatric dose-finding is also underway. Relay Therapeutics plans to further refine patient-reported outcomes and continue Phase 3 preparation for zovegalisib’s use in breast cancer, a separate large indication. Additional data from later timepoints and expanded populations will be watch areas for investors following RLAY.
Key Data at a Glance
| Metric | Value |
|---|---|
| Stock Price (as of 10:09 AM) | $12.52 |
| Volumetric Response Rate (12 weeks) | 60% |
| Proportion of Patients with Lesion Reduction | 95% |
| Clinical Improvement (Clinician/Patient-Reported) | 89% / 79% |
| Grade 3+ Adverse Events | 9% |
| Patients Discontinued Due to Side Effects | 0 |
Takeaway: Zovegalisib’s Strong Benefit-Risk Profile Sets RLAY Apart in Rare Disease Space
Relay’s early-stage clinical data for zovegalisib shows potential not only for rapid and meaningful responses in PIK3CA-driven vascular anomalies, but also a safety profile that could allow for long-term use—an essential consideration in these chronic and often refractory conditions. With Part 2 of the trial now open at preferred doses and pediatric cohorts progressing, further updates could clarify zovegalisib’s place in the rare disease landscape.
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