Relay Therapeutics Inc (NASDAQ: RLAY) experienced a premarket uptick of 3.8% on Tuesday after announcing that the U.S. Food and Drug Administration has granted Breakthrough Therapy designation to its investigational agent zovegalisib when given with fulvestrant.
The designation applies specifically to adults with PIK3CA-mutant, hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) locally advanced or metastatic breast cancer who have demonstrated recurrence or progression after treatment with a CDK4/6 inhibitor.
The FDA created the Breakthrough Therapy pathway to accelerate the development and review timeline for treatments addressing serious conditions when early clinical data suggest the new therapy may offer substantial improvement over current options. As part of the designation, companies receive enhanced guidance from the agency and more interaction with senior FDA leadership.
Don Bergstrom, President of Research and Development at Relay Therapeutics, highlighted the patient population the designation targets, saying: "Approximately 40% of patients with HR+/HER2- advanced breast cancer harbor PIK3CA mutations, and most experience disease recurrence or progression following treatment with CDK4/6 inhibitors, leaving limited therapeutic options."
Relay said the Breakthrough Therapy request was supported by clinical findings from its Phase 1/2 ReDiscover study, which evaluated zovegalisib paired with fulvestrant. The regulatory submission included data pooled across all PIK3CA mutations for two dosing regimens that produced comparable systemic exposures: 600 mg twice daily (BID) taken fasted, and 400 mg BID taken fed. The 400 mg BID fed schedule is the dosing regimen currently employed in the ongoing Phase 3 trial, ReDiscover-2.
Based in Cambridge, Massachusetts, Relay Therapeutics has scheduled a presentation of initial Phase 1/2 results using the 400 mg BID fed dose in patients previously treated with CDK4/6 inhibitors at the ESMO Targeted Anticancer Therapies Congress on March 16.
Context and market reaction
The immediate market response was modestly positive, with the company's shares rising in premarket activity following the FDA announcement. The designation is intended to facilitate more intensive agency engagement as Relay continues its late-stage development program for zovegalisib in this biomarker-defined breast cancer subgroup.
What happens next
Relay will continue enrollment and evaluation in its Phase 3 ReDiscover-2 study while preparing to disclose detailed Phase 1/2 findings at the ESMO congress. The company will also work with the FDA under the Breakthrough Therapy framework, which typically includes more frequent interactions to help guide development and regulatory strategy.