New data from the lidERA Phase 3 trial showed that adjuvant giredestrant, an investigational oral selective estrogen receptor degrader (SERD), cut recurrence risk across both premenopausal and postmenopausal subgroups with ER+/HER2− early breast cancer. The report describes invasive disease-free survival (iDFS) benefits versus standard-of-care endocrine therapy, with results presented as part of the trial’s broader readout. Among 1687 premenopausal patients, giredestrant reduced the risk of invasive disease or death by 35% (HR 0.65), with 3-year iDFS rates of 94.0% vs 91.5% compared with standard therapy. Among 2456 postmenopausal patients, the hazard ratio was 0.74 (3-year iDFS 91.3% vs 88.3%). Investigators also reported fewer musculoskeletal-pain-driven treatment discontinuations on giredestrant than on comparator regimens. The trial is described as the largest randomized evaluation of an oral SERD in the adjuvant setting, and the readout positions giredestrant as an option aimed at more complete ER blockade than tamoxifen and with an administration advantage versus fulvestrant’s intravenous delivery.