Relay Therapeutics (NASDAQ:RLAY) presented promising subset efficacy data from its ReDiscover program at the 2025 San Antonio Breast Cancer Symposium (SABCS), showcasing the combination of zovegalisib (RLY-2608) and fulvestrant in a cohort of 52 patients with estrogen receptor-positive breast cancer.
The data, which were based on a 600mg BID fasted dose with no PTEN/AKT co-mutation, revealed a median progression-free survival (PFS) of 10.3 months overall and 11.4 months in second-line (2L) patients.
Among the 31 patients with measurable disease, the overall objective response rate (ORR) was 39%, with a higher response rate of 47% observed in 2L patients.
Patients previously treated with selective estrogen receptor degraders (SERDs) showed a PFS of 11.4 months and an ORR of 44%, while ESR1-mutant patients demonstrated a PFS of 8.8 months and an impressive ORR of 60%.
The safety profile of the combination treatment remained mostly low-grade and manageable, supporting its potential for further development as a therapeutic option for breast cancer patients.