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lidERA — Giredestrant (oral SERD) vs standard endocrine therapy, adjuvant ER+/HER2− early breast cancer

Abstract: 502 · Session: Oral Abstract Session, Breast Cancer — Local/Regional/Adjuvant, Sat May 30, 2026, 1:39–1:51 PM CT · Presenter: Peter Schmid, MD, PhD (Queen Mary University of London) · Embargo: May 30, 2026

At a glance

  • Sponsor: Roche / Genentech
  • PI / presenter: Peter Schmid, MD, PhD, FACP — Queen Mary University of London (Barts Cancer Institute)
  • NCT ID: NCT04961996
  • Phase: III
  • Design: Global, randomized, open-label. Stage I–III ER+/HER2− early breast cancer, surgery within 12 months; randomized 1:1 to giredestrant 30 mg PO daily vs physician's-choice standard-of-care endocrine therapy (tamoxifen, anastrozole, letrozole, or exemestane) for ≥5 years, followed by 5 years of observation. Stratified analyses by menopausal status.
  • N: 4,170 (giredestrant n≈2,069; SOC ET n≈2,074; 1,687 premenopausal, 2,456 postmenopausal)
  • Primary endpoint(s): Invasive disease-free survival (iDFS)
  • Comparator: Physician's-choice standard-of-care endocrine therapy (tamoxifen / anastrozole / letrozole / exemestane)
  • Indication: ER+/HER2− early breast cancer (stage I–III), adjuvant
  • Line: Adjuvant (post-surgery)

Headline result

Adjuvant giredestrant significantly improved iDFS vs standard-of-care endocrine therapy: HR 0.70 (95% CI 0.57–0.87; P=0.0014), a 30% reduction in the risk of invasive disease or death. Three-year iDFS was 92.4% with giredestrant vs 89.6% with ET. Benefit was consistent across menopausal status — premenopausal iDFS HR 0.65 (95% CI 0.44–0.95; 3-yr 94.0% vs 91.5%) and postmenopausal HR 0.74 (95% CI 0.57–0.96; 3-yr 91.3% vs 88.3%) — and was accompanied by improved distant recurrence-free interval (premenopausal DRFI HR 0.58, 95% CI 0.38–0.90; postmenopausal DRFI HR 0.76, 95% CI 0.56–1.04). Giredestrant carried a favorable safety profile with lower treatment discontinuation; discontinuations due to musculoskeletal pain were less than half as common as with AI. This is the first phase III trial to show benefit with an oral SERD in the adjuvant setting.

Mechanism / class

Giredestrant is a next-generation, investigational oral selective estrogen receptor degrader (SERD) and full ER antagonist — it both degrades and antagonizes the estrogen receptor. Oral SERDs are designed to overcome ESR1-mutation–driven endocrine resistance and improve on fulvestrant (an injectable SERD). No SERD is currently approved in the adjuvant early-breast-cancer setting; elacestrant (oral SERD) is approved only for ESR1-mutant metastatic disease.

Discussant takeaway

Framed by Roche/ASCO coverage as a potential new standard of care in adjuvant ER+/HER2− early breast cancer, given the first positive phase III oral-SERD adjuvant result, magnitude of iDFS benefit, consistency across menopausal status, and improved tolerability vs AI. (Named formal ASCO discussant not reported in available sources.)

Practice-changing?

Pending → likely yes. A 30% iDFS reduction in a 4,170-patient adjuvant trial with a favorable tolerability profile is positioned as practice-changing, but durability of the 3-year benefit, overall survival, and regulatory approval remain to be established before adoption.

Sources

  • ASCO Meeting Library / abstract 502 (J Clin Oncol. 2026;44(suppl 16)) — via trade-press coverage below
  • CancerNetwork: https://www.cancernetwork.com/view/adjuvant-giredestrant-improves-invasive-dfs-er-her2-early-breast-cancer
  • OncLive: https://www.onclive.com/view/giredestrant-vs-standard-of-care-endocrine-therapy-as-adjuvant-treatment-for-patients-with-estrogen-receptor-positive-her2-negative-early-breast-cancer-results-from-the-global-phase-iii-lidera-breast-cancer-trial
  • The ASCO Post: https://ascopost.com/issues/january-25-2026/novel-endocrine-therapy-giredestrant-improves-invasive-disease-free-survival-in-estrogen-receptor-positive-her2-negative-early-breast-cancer/
  • Cancer Therapy Advisor: https://www.cancertherapyadvisor.com/reports/menopausal-status-giredestrant-efficacy-er-her2-early-breast-cancer/
  • Roche press release (May 19, 2026): https://www.roche.com/media/releases/med-cor-2026-05-19
  • OncLive ASCO 2026 breast preview: https://www.onclive.com/view/asco-2026-breast-cancer-preview-read-up-on-the-insights-to-know-before-you-go