Clinical TrialApr 27, 2026, 06:03 AM
RLAY Zovegalisib Triplet Advances to Frontline Phase 3; 44% ORR
AI Summary
Relay Therapeutics announced plans to advance zovegalisib + atirmociclib, Pfizer’s investigational CDK4 inhibitor, into Phase 3 development for frontline PI3Kα-mutated, HR+/HER2- metastatic breast cancer. This decision is supported by compelling efficacy and tolerability data from the ReDiscover study in heavily pre-treated, median third-line patients. The triplet regimen achieved a 44% objective response rate (ORR) in CDK4/6-experienced patients, with a favorable safety profile including 0% Grade 3 hyperglycemia. A Phase 3 frontline trial is expected to start in early 2027, and Pfizer will supply atirmociclib for the trial.
Key Highlights
- Zovegalisib triplet regimen selected for frontline Phase 3 development in PI3Kα-mutated, HR+/HER2- metastatic breast cancer.
- Achieved 44% Objective Response Rate (ORR) in 34 heavily pre-treated, CDK4/6-experienced patients (median 3L).
- ORR was consistent at 44% across both kinase and non-kinase PIK3CA mutations.
- Only 2 patients (3%) discontinued zovegalisib due to treatment-related adverse events (TRAEs) (N=62).
- Grade 3 hyperglycemia was 0% despite 47% of patients being pre-diabetic.
- Overall Grade 3+ TRAE rate was 40% in median third-line patients, with neutropenia accounting for most events.
- 77% (48 of 62) of patients remained on study as of the April 13, 2026 data cut-off.
- Phase 3 frontline trial expected to initiate in early 2027, subject to regulatory feedback. Pfizer to supply atirmociclib.