Multiple doses achieved sustained target exposure of ~80%+ mutant PI3Kα inhibition
No Grade 3 hyperglycemia, rash or diarrhea observed at target exposures
Favorable initial safety profile at target exposures
Confirmed partial response in breast cancer patient with 12 prior lines of therapy
Initial anti-tumor activity in breast cancer patients observed across range of doses
Relay Therapeutics to host a conference call today, April 18, at 1:30 p.m. ET
ORLANDO, Fla., April 18, 2023 (GLOBE NEWSWIRE) — Relay Therapeutics, Inc. (NASDAQ:RLAY), a clinical-stage precision medicine company transforming the drug discovery process by combining leading-edge computational and experimental technologies, today announced initial clinical data for RLY-2608, the first known investigational allosteric, pan-mutant and isoform-selective inhibitor of PI3Kα. The data support initial clinical proof of mechanism, demonstrating that RLY-2608 achieved selective target engagement at multiple predicted efficacious doses with a favorable initial safety and tolerability profile. These data are being presented today at the American Association for Cancer Research (AACR) Annual Meeting 2023.
“While early, these data suggest that by selectively inhibiting mutant PI3Kα and avoiding key off-target toxicities that typically limit the use of non-selective PI3Kα pathway inhibitors, RLY-2608 has the potential to transform treatment for patients with a broad range of PI3Kα mutations,” said Don Bergstrom, M.D., Ph.D., President of R&D at Relay Therapeutics. “At doses achieving target exposure, there was no observed Grade 3 hyperglycemia, rash or diarrhea – the three most common adverse events leading to discontinuation of existing investigational and approved treatments, and radiographic tumor reductions were seen across multiple dose levels. We are continuing dose escalation and expect to initiate expansion cohorts in the second half of 2023.”
ReDiscover – RLY-2608 First-in-Human Trial
RLY-2608 is currently being evaluated in an ongoing dose-escalation portion of ReDiscover, a first-in-human trial, which was designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics and preliminary antitumor activity across two separate arms. The monotherapy arm started in December 2021 and enrolled 19 patients with unresectable or metastatic solid tumors with a PI3Kα mutation. This arm included a broad diversity of solid tumors, predominantly tumor types not predicted to be sensitive to single agent PI3Kα inhibition. The RLY-2608 + fulvestrant combination arm started April 2022 and enrolled 23 patients with PI3Kα-mutant, HR+, HER2– locally advanced or metastatic breast cancer. Across both arms of the study, enrolled patients had received a significant level of prior therapy, including all breast cancer patients who had received at least one prior endocrine therapy and CDK4/6 inhibitor. The cut-off date for data reported at AACR was March 9, 2023.
