On June 6, 2024 Relay Therapeutics, Inc. (Nasdaq: RLAY), a clinical-stage precision medicine company transforming the drug discovery process by combining leading-edge computational and experimental technologies, reported a clinical trial collaboration with Pfizer Inc. (NYSE: PFE) to evaluate atirmociclib, Pfizer’s investigative selective-CDK4 inhibitor, in combination with RLY-2608 and fulvestrant in patients with PI3Kα-mutated, HR+, HER2- metastatic breast cancer (Press release, Relay Therapeutics, JUN 6, 2024, View Source [SID1234644175]).
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"We are very enthusiastic to evaluate Pfizer’s novel investigative selective-CDK4 inhibitor atirmociclib in combination with RLY-2608, the first mutant selective PI3Kα inhibitor," said Don Bergstrom, M.D., Ph.D., President of R&D at Relay Therapeutics. "We believe that combining these two selective agents – atirmociclib and RLY-2608 – will avoid key off-target toxicity that comes from hitting CDK6 and wild-type PI3Kα, which has historically significantly limited use of non-selective agents. The breast cancer treatment landscape continues to evolve quickly, and we are pleased that the safety profile RLY-2608 has demonstrated to-date makes it well-positioned to be part of the next generation of therapies."
Under the terms of the agreement, Pfizer will provide atirmociclib for use in the study and Relay will be responsible for conducting the study. The RLY-2608 + atirmociclib + fulvestrant triplet combination is planned to begin by the end of 2024.
About RLY-2608
RLY-2608 is the lead program in Relay Therapeutics’ efforts to discover and develop mutant selective inhibitors of PI3Kα, the most frequently mutated kinase in all cancers, with oncogenic mutations detected in about 14% of patients with solid tumors. RLY-2608 has the potential, if approved, to address more than 250,000 patients per year in the United States, one of the largest patient populations for a precision oncology medicine.
Traditionally, the development of PI3Kα inhibitors has focused on the active, or orthosteric, site. The therapeutic index of orthosteric inhibitors is limited by the lack of clinically meaningful selectivity for mutant versus wild-type (WT) PI3Kα and off-isoform activity. Toxicity related to inhibition of WT PI3Kα and other PI3K isoforms results in sub-optimal inhibition of mutant PI3Kα with reductions in dose intensity and frequent discontinuation. The Dynamo platform enabled the discovery of RLY-2608, the first known allosteric, pan-mutant, and isoform-selective PI3Kα inhibitor, designed to overcome these limitations. Relay Therapeutics solved the full-length cryo-EM structure of PI3Kα, performed computational long time-scale molecular dynamic simulations to elucidate conformational differences between WT and mutant PI3Kα, and leveraged these insights to support the design of RLY-2608. RLY-2608 is currently being evaluated in a first-in-human trial designed to treat patients with advanced solid tumors with a PIK3CA (PI3Kα) mutation. For more information on RLY-2608, please visit here.