Relay Therapeutics (RLAY), a clinical-stage, small molecule precision medicine company, announced plans to move Zovegalisib plus Atirmociclib, Pfizer's investigational, potential CDK4 inhibitor, into Phase 3 development for frontline patients with PI3Ka-mutated, HR+/HER2- metastatic breast cancer.
The planned study, subject to regulatory feedback, is a randomised Phase 3 trial evaluating Zovegalisib in combination with Atirmociclib and aromatase inhibitor (AI) in frontline endocrine sensitive patients with PIK3CA-mutated, HR+/HER2- advanced or metastatic breast cancer.
The trial is expected to commence in early 2027, subject to regulatory feedback.The key endpoints include median progression-free survival as the primary endpoint and overall survival as the secondary endpoint.
For the planned study, Pfizer has agreed to supply Atirmociclib for the experimental arm, in combination with Zovegalisib, and palbociclib for the control arm.
Zovegalisib is currently being evaluated in ReDiscover, an ongoing first-in-human study designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary antitumor activity of Zovegalisib in combination with Fulvestrant and CDK inhibitors in patients with PI3Ka-mutated, HR+/HER2- metastatic breast cancer.
As of the April 13, 2026 data cut-off date, 69 patients were enrolled, and 34 were evaluable for response, and the Objective response rate (ORR) was 44% (15/34) and was also 44% in both kinase and non-kinase patients. Nearly 85% of patients experienced tumour reduction.
"While PI3Ka inhibition has demonstrated meaningful benefit in breast cancer, its use in the frontline setting has been limited by tolerability challenges with earlier agents," said Don Bergstrom at Relay Therapeutics.
RLAY has traded between $2.67 and $17.32 over the last year. The stock closed Friday's trade at $15.13, up 0.27%.
In the pre-market, RLAY is up 0.13% at $15.15.
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April 24, 2026 15:15 ET Economics news flow was relatively light this week even as the conflict in the Middle East continued, raising concerns for policymakers. In the U.S., spending data, initial jobless claims and pending home sales were the highlights. Business confidence in the biggest euro area economy was in focus in Europe. Inflation data from Japan gained attention in Asia.