In a recent press release, Relay Therapeutics shared that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to zovegalisib combined with fulvestrant in patients with advanced or metastatic breast cancer.
Breakthrough Therapy designation allows for expedited review of drugs for serious diseases with promising clinical data. In addition, the designation provides increased guidance from FDA officials and senior managers.
The designation applies to adults with hormone-receptor positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer and mutations in the PIK3CA gene. Up to 40% of these patients experience progression or recurrence after receiving CDK4/6 inhibitors, the current standard of care.
This milestone comes following positive results from the Phase 1/2 ReDiscover clinical trial, in which participants received 600 mg zovegalisib twice daily on an empty stomach along with fulvestrant.
The company is also investigating the safety and efficacy of 400 mg zovegalisib twice daily. Relay will present this data at an upcoming conference in March 2026.
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“This Breakthrough Therapy designation underscores the FDA’s recognition of the potential of zovegalisib in combination with fulvestrant to meaningfully improve outcomes for these patients,” said Don Bergstrom, president of research and development at Relay. “We look forward to continuing to collaborate closely with the FDA as we work to advance this program as efficiently as possible for patients.”
Zovegalisib inhibits phosphoinositide 3-kinase alpha (PI3Kα), a protein that is often mutated in different cancers. Unlike existing PI3Kα inhibitors, zovegalisib binds with a different portion of the protein to prevent targeting of unmutated PI3Kα.
Fulvestrant is a selective estrogen receptor degrader that is approved for patients with HR+/HER2- advanced breast cancer.
If approved, zovegalisib has the potential to treat 140,000 patients with PIK3CA mutant HR+/HER2- breast cancer, Relay stated. The drug may also be effective in patients with vascular abnormalities caused by PIK3CA mutations.
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