Relay Therapeutics Announces Zovegalisib Granted Breakthrough Therapy Designation by U.S. FDA for PIK3CA-mutant, HR+/HER2- Advanced Breast Cancer

Core Insights - The FDA has granted Breakthrough Therapy designation to zovegalisib in combination with fulvestrant for treating adults with PIK3CA mutant, HR+/HER2- locally advanced or metastatic breast cancer [1][2][3] Group 1: Clinical Data and Trials - The Breakthrough Therapy designation is supported by clinical data from the Phase 1/2 ReDiscover trial, which evaluated zovegalisib's safety, tolerability, pharmacokinetics, and preliminary antitumor activity [3][4] - Initial Phase 1/2 data for zovegalisib + fulvestrant at the 400mg BID fed dose will be presented at the ESMO Targeted Anticancer Therapies Congress on March 16, 2026 [1][4] - The ReDiscover trial included data from two doses: 600mg BID fasted (N=52) and 400mg BID fed (N=57), with the latter being the dose used in the ongoing Phase 3 trial [3] Group 2: Market Potential and Patient Impact - Approximately 40% of patients with HR+/HER2- advanced breast cancer have PIK3CA mutations, leading to limited treatment options after CDK4/6 inhibitors [2][8] - Zovegalisib has the potential to address a significant portion of the estimated 140,000 patients with HR+, HER2- breast cancer with a PI3Kα mutation annually in the U.S. [5] Group 3: Mechanism and Innovation - Zovegalisib is the first known allosteric, pan-mutant, and isoform-selective PI3Kα inhibitor, designed to overcome limitations of traditional PI3Kα inhibitors [6] - The development of zovegalisib utilized advanced computational methods to elucidate conformational differences between wild-type and mutant PI3Kα [6]