ASCO 2026: lidERA BC Phase 3 — Giredestrant Oral SERD Reduces Breast Cancer Recurrence by 30% in Early ER+/HER2- Disease

The Phase 3 lidERA BC trial, presented by Roche/Genentech at ASCO 2026, showed that giredestrant — an investigational once-daily oral selective estrogen receptor degrader (SERD) — reduces the risk of invasive disease recurrence or death by 30% in patients with Stage I–III ER-positive/HER2-negative early breast cancer following surgery. The trial enrolled 4,170 women who received giredestrant versus standard endocrine therapy (aromatase inhibitors or tamoxifen). Three-year invasive disease-free survival (IDFS) was 94.0% (giredestrant) vs. 91.5% (standard of care), with the absolute benefit greatest in premenopausal patients and those with higher-risk disease features. Giredestrant is a non-steroidal, orally bioavailable SERD that degrades the estrogen receptor protein without the injection-site reactions associated with fulvestrant. Unlike older SERDs, giredestrant is taken as a once-daily pill. The result positions giredestrant as the first oral SERD with demonstrated efficacy advantage over standard endocrine therapy in the early-stage adjuvant setting — potentially replacing aromatase inhibitors as the standard of care. A separate Phase 3 trial (PersevERA) in first-line metastatic HR+ breast cancer did not meet its primary PFS endpoint, suggesting giredestrant's strongest benefit may be in the early-stage curative setting. The FDA granted giredestrant Fast Track Designation on June 2, 2026, based on the ASCO data.