US-based clinical-stage precision medicine company Relay Therapeutics, Inc. (NASDAQ: RLAY) on Tuesday said the US Food and Drug Administration has granted Breakthrough Therapy designation to zovegalisib in combination with fulvestrant for adults with PIK3CA-mutant, hormone receptor-positive, HER2-negative locally advanced or metastatic breast cancer after progression on a CDK4/6 inhibitor.

The designation is supported by clinical data from the Phase 1/2 ReDiscover trial evaluating safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary antitumour activity of zovegalisib with fulvestrant.

The application included data across all PIK3CA mutations for two doses with comparable exposure: 600mg twice daily fasted (n=52) and 400mg twice daily fed (n=57), the latter being the dose used in the ongoing Phase 3 ReDiscover-2 study.

Breakthrough Therapy designation is intended to accelerate development and regulatory review for therapies addressing serious conditions where early clinical evidence suggests substantial improvement over available treatments, and includes Fast Track features and increased FDA engagement.

Zovegalisib is Relay Therapeutics' lead clinical programme and is being evaluated in multiple metastatic breast cancer studies as well as a first-in-human study in PIK3CA mutation-driven vascular anomalies.