05:04 PM EDT, 06/05/2024 (MT Newswires) -- Relay Therapeutics ( RLAY ) unveiled late Wednesday a clinical trial collaboration with Pfizer ( PFE ) to evaluate a treatment for patients with PI3Ka-mutated, HR+, HER2- metastatic breast cancer.

The partnership is evaluating atirmociclib, Pfizer's ( PFE ) investigative selective-CDK4 inhibitor, in combination with RLY-2608 and fulvestrant, Relay Therapeutics ( RLAY ) said.

Atirmociclib and RLY-2608 "will avoid key off-target toxicity that comes from hitting CDK6 and wild-type PI3Ka, which has historically significantly limited use of non-selective agents," said Don Bergstrom, president of research and development at Relay Therapeutics ( RLAY ).

Pfizer ( PFE ) will provide atirmociclib for use in the collaboration, and Relay will be responsible for conducting the study. The RLY-2608 plus atirmociclib plus fulvestrant triplet combination is planned to begin by the end of 2024, Relay Therapeutics ( RLAY ) said.

Shares of Relay Therapeutics ( RLAY ) rose 5.2% in after-hours trading Wednesday, and Pfizer ( PFE ) rose 0.2% in the regular session.

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