Relay Therapeutics’ Zovegalisib Receives Breakthrough Therapy Designation for Advanced Breast Cancer
Wednesday, February 04, 2026
Relay Therapeutics has announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to zovegalisib (RLY-2608).
Zovegalisib is Relay Therapeutics’ lead programme targeting PI3Kα, one of the most commonly mutated kinases in cancer. Unlike earlier PI3Kα inhibitors, which often lack selectivity and cause dose-limiting side effects, zovegalisib is designed as an allosteric, pan-mutant and isoform-selective inhibitor. This approach aims to reduce toxicity while maintaining effective inhibition of mutant PI3Kα.
HR+/HER2- breast cancer is the most common form of the disease. Patients with activating PIK3CA mutations often have poorer outcomes compared to those without such mutations. While CDK4/6 inhibitors combined with endocrine therapy remain standard treatment, there are currently no approved therapies that include a pan-mutant selective PI3Kα inhibitor for this group.
PIK3CA mutations are found in around 40% of patients with HR+/HER2- advanced breast cancer. Many of these patients experience disease progression after standard CDK4/6 inhibitor therapy, leaving limited treatment options. The FDA’s decision reflects the potential of zovegalisib to address this unmet clinical need and to improve outcomes in this patient population.
The designation applies to the use of zovegalisib in combination with fulvestrant for adults with PIK3CA-mutant, hormone receptor-positive and HER2-negative (HR+/HER2-) locally advanced or metastatic breast cancer whose disease has progressed following treatment with a CDK4/6 inhibitor.
Breakthrough Therapy designation is intended to speed up the development and regulatory review of medicines for serious conditions where early clinical results indicate a meaningful benefit over existing therapies.
The designation was supported by clinical data from the ongoing Phase 1/2 ReDiscover trial. This study is evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics and early anti-tumour activity of zovegalisib in combination with fulvestrant, as well as in combination with fulvestrant and CDK inhibitors. Data included results across different PIK3CA mutations using two dosing regimens: 600 mg twice daily taken fasted and 400 mg twice daily taken with food, the latter being the dose selected for the ongoing Phase 3 ReDiscover-2 trial.
The designation offers access to Fast Track features, along with closer interaction and guidance from the FDA during the development process.
Source: globenewswire.com
