Relay Therapeutics Reports 'Robust Activity' For Precision Breast Cancer Drug

Relay Therapeutics, Inc. (NASDAQ:RLAY) on Friday shared a subset analysis of interim clinical data for zovegalisib (RLY-2608).

Subset analyses showed broad activity in patients with PI3Kα-mutated, HR+/HER2- metastatic breast cancer, regardless of prior fulvestrant or other SERD exposure or ESR1 mutation status.

These data were presented at the 2025 San Antonio Breast Cancer Symposium (SABCS).

Also Read: Roche’s Oral Breast Cancer Drug Shows 30% Drop In Recurrence In Patients With Early Disease

As of the data cut-off date of October 15, 2025, 118 patients had enrolled into the zovegalisib + fulvestrant arm of the ReDiscover study.

Efficacy Consistent Across Subset Populations

The total efficacy population consisted of 52 zovegalisib + fulvestrant patients who received 600mg BID fasted and did not have a PTEN or AKT co-mutation. Median follow-up was 20.2 months.

The median progression-free survival (PFS) was 10.3 months for all patients. Among the total of 31 patients with measurable disease, the objective response rate (ORR) was 39%.

For second-line (2L) patients, median PFS was 11.4 months, and ORR was 47%. Efficacy was generally consistent across other subsets of patients.

For patients who received prior SERD, median PFS was 11.4 months, and ORR was 44% (7/16), and for patients who had a detectable ESR1 mutation at baseline, median PFS was 8.8 months, and ORR was 60% (6/10).

The overall tolerability profile remained consistent with mutant-selective PI3Kα inhibition, with treatment-related adverse events that were primarily low-grade, manageable, and reversible.

Anticipated Zovegalisib Next Steps

• Continued enrollment of Phase 3 ReDiscover-2 trial of zovegalisib + fulvestrant in PI3Kα-mutated, CDK4/6 pre-treated, HR+/HER2- advanced breast cancer
• Continued dose escalation in Phase 1/2 ReDiscover trial, advancing triplet cohorts that will inform which regimen could be used in a future frontline metastatic trial.
• Continued enrollment of the ongoing Phase 1/2 ReInspire clinical trial in vascular malformations.

Wells Fargo upgraded Relay Therapeutics from Equal-Weight to Overweight and raised the price forecast from $6 to $13.

Program Overview

Zovegalisib is the lead 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 malformations.

Zovegalisib has the potential, if approved, to address nearly 500,000 patients in the United States, one of the largest patient populations for a precision medicine.

“Data presented today demonstrate the robust activity of zovegalisib + fulvestrant across subgroups of patients whose baseline characteristics are known to affect outcomes, such as prior fulvestrant or SERD and ESR1 mutation status,” said Don Bergstrom, M.D., Ph.D., President of R&D at Relay Therapeutics.

“The broad range of activity highlights the importance of selectively targeting the driver of disease, mutant PI3Kα, and gives us confidence that the data observed to date should translate to our ongoing Phase 3 trial, ReDiscover-2.”

RLAY Price Action: Relay Therapeutics shares were up 3.21% at $8.03 at the time of publication on Friday. The stock is trading near its 52-week high of $8.36, according to Benzinga Pro data.

Read Next:

• Nvidia Eyes Bigger AI Chip Output After China Orders Flood In

Image via Shutterstock