ESMO 2026 Breast Cancer: 10 Studies to Watch in MadridESMO Congress 2026

Rodrigo Arrangoiz MS, MD, FACS, FSSO
  • ESMO 2026 Breast Cancer: 10 Studies to Watch in Madrid
    ESMO Congress 2026 takes place in Madrid, Spain, from 23 to 27 October 2026. OncoDaily picked ten breast cancer abstracts from the official programme. The programme covers both early and advanced disease, with late-breaking phase III trials, mature overall survival (OS) analyses, post-CDK4/6 strategies, biomarker studies and a growing focus on how to sequence antibody–drug conjugates (ADCs). [1]
    Early breast cancer
    1. TALENT (LBA23): T-DXd before surgery in HER2-low, HR+ disease
    This presentation reports final results of a neoadjuvant study testing trastuzumab deruxtecan (T-DXd) with or without anastrozole, or in sequence with chemotherapy, in HER2-low, HR-positive early breast cancer. Earlier data from the phase II trial were presented at SABCS 2022, where investigators stressed that pCR and response results were not yet mature because not all patients had completed scans or surgery. [2, 3]
    2. NATALEE (LBA25): Six-year follow-up of adjuvant ribociclib
    ESMO 2026 will show six-year OS and efficacy outcomes for adjuvant ribociclib plus a nonsteroidal aromatase inhibitor in HR+/HER2− early breast cancer. At the 5-year analysis, invasive disease-free survival was 85.5% with ribociclib plus endocrine therapy versus 81.0% with endocrine therapy alone, a 4.5% absolute improvement. The hazard ratio was 0.716 (95% CI 0.618–0.829). OS data were still immature at that point. [4, 5]
    Advanced HR+/HER2− breast cancer
    3. PANKU-Breast01 (LBA50): iza-bren after prior treatment
    This randomized phase III study tests izalontamab brengitecan in previously treated, unresectable locally advanced or metastatic HR+/HER2− breast cancer. The same drug, an EGFR×HER3 bispecific ADC, already succeeded in triple-negative disease. In the PANKU-Breast02 trial in pretreated TNBC, presented at ASCO 2026, the hazard ratio for PFS was 0.29. Risk of death was 40% lower (HR 0.60; 95% CI 0.42–0.85). [6]
    4. KEYNOTE-B49 (LBA51): Pembrolizumab plus chemotherapy
    This double-blind phase III study compares pembrolizumab with placebo, both added to chemotherapy, in HR+/HER2− advanced breast cancer. It enrolled about 800 patients with PD-L1 CPS ≥1 tumours who had progressed on endocrine therapy and had not received chemotherapy for metastatic disease. These will be the first reported results. [7, 8]
    5. FINER / MA.40 (LBA14): OS with ipatasertib plus fulvestrant
    This presentation reports OS from the randomized phase III trial of fulvestrant plus ipatasertib in ER+/HER2− metastatic breast cancer. The trial randomized 250 patients whose disease had progressed after first-line CDK4/6 inhibitor plus aromatase inhibitor. At ASCO 2025, median PFS was 5.32 months with ipatasertib versus 1.94 months with placebo. In patients with AKT-pathway alterations, median PFS was 5.45 vs 1.91 months (HR 0.47). [9, 10]
    6. VIKTORIA-1 (LBA16): Updated gedatolisib results
    This presentation gives updated results for gedatolisib plus fulvestrant, with or without palbociclib, versus standard of care in HR+/HER2− advanced breast cancer. In the PIK3CA wild-type cohort, median PFS was 9.3 months with the triplet versus 2.0 months with fulvestrant (HR 0.24), and 7.4 months with the doublet (HR 0.33). These results were published in the Journal of Clinical Oncology in March 2026. The FDA has since approved gedatolisib for HR+/HER2−, PIK3CA wild-type advanced breast cancer. [11, 12]
    7. evERA (2RO): Biomarker analyses for giredestrant plus everolimus
    The focus here is retrospective exploratory biomarker analyses, not another efficacy readout. In the primary analysis, median PFS was 8.77 months with giredestrant plus everolimus versus 5.49 months with endocrine therapy plus everolimus (HR 0.56; 95% CI 0.44–0.71). The benefit was larger in ESR1-mutated tumours, with a 62% reduction in risk of progression or death. [13, 14]
    8. postMONARCH (1RO): OS with abemaciclib after a prior CDK4/6 inhibitor
    This presentation reports OS for abemaciclib plus fulvestrant versus placebo plus fulvestrant after progression on a CDK4/6 inhibitor plus endocrine therapy. The primary analysis of 368 patients showed a PFS hazard ratio of 0.73, with median PFS of 6.0 vs 5.3 months. Blinded central review supported this result (HR 0.55). [15, 16]
    Triple-negative disease and ADC sequencing
    9. OptiTROP-Breast01 (4639RO): Final OS for sac-TMT
    This is the final OS analysis of sacituzumab tirumotecan versus chemotherapy in previously treated metastatic TNBC. In the published phase III data, median PFS by central review was 6.7 vs 2.5 months (HR 0.32). At the interim OS analysis, median OS was not reached with sac-TMT versus 9.4 months with chemotherapy (HR 0.53). [17, 18]
    10. SWITCH (4RO): What to do after a first ADC stops working
    This is a prospective phase II platform trial in metastatic breast cancer after prior ADC therapy. It tests switching to a novel ADC with a different target but the same type of payload. No earlier results have been published. [1]
    The bottom line
    Four of these studies bring long-awaited survival data: NATALEE, FINER, postMONARCH and OptiTROP-Breast01. The rest address newer questions, including ADCs in early HER2-low disease, immunotherapy in HR+ disease, treatment after CDK4/6 inhibitors, and what to give after an ADC. The common theme is choosing the right sequence of treatments, not just finding one new active drug.
    References
    Gevorgyan A. ESMO Congress 2026 Breast Cancer: 10 Abstracts to Watch. OncoDaily, 28 Sep 2026. https://oncodaily.com/breast-oncology/esmo-congress-2026-bc
    Hurvitz S, et al. Final results of TALENT. ESMO 2026, LBA23.
    Hurvitz SA, Bardia A, et al. TRIO-US B-12 TALENT. SABCS 2022, GS2-03. https://ascopost.com/news/december-2022/neoadjuvant-t-dxd-shows-clinical-activity-in-patients-with-her2-low-breast-cancer/
    Slamon D, et al. NATALEE 6-year OS. ESMO 2026, LBA25.
    NATALEE 5-year follow-up (PMC); Novartis press release, 17 Oct 2025. https://pmc.ncbi.nlm.nih.gov/articles/12684762 · https://www.novartis.com/news/media-releases/novartis-kisqali-5-year-natalee-data-demonstrate-28-reduction-risk-recurrence-broadest-early-breast-cancer-patient-population
    Lan B, et al. PANKU-Breast01. ESMO 2026, LBA50. PANKU-Breast02 background: https://www.cancernetwork.com/view/izalontamab-brengitecan-improves-os-pfs-in-advanced-metastatic-tnbc
    Rugo H, et al. KEYNOTE-B49. ESMO 2026, LBA51.
    KEYNOTE-B49 trial design (ASCO TPS); ClinicalTrials.gov NCT04895358. https://ace.asco.org/content/370330/abstract/213426
    Redfern A, et al. FINER OS. ESMO 2026, LBA14.
    Chia S, et al. FINER, ASCO 2025. https://www.hmpgloballearningnetwork.com/site/onc/conference-coverage/ipatasertib-plus-fulvestrant-significantly-prolongs-progression-free
    Pistilli B, et al. VIKTORIA-1 update. ESMO 2026, LBA16.
    VIKTORIA-1, J Clin Oncol, Mar 2026; FDA approval coverage. https://www.targetedonc.com/view/fda-approves-gedatolisib-for-hr-her2-pik3ca-wild-type-advanced-breast-cancer
    Tolaney S, et al. evERA biomarker analyses. ESMO 2026, 2RO.
    evERA primary results, ESMO 2025. https://www.cancernetwork.com/view/giredestrant-combo-yields-positive-pfs-in-subgroups-after-cdk4-6i-in-er-her2-breast-cancer
    Kalinsky K, et al. postMONARCH OS. ESMO 2026, 1RO.
    Kalinsky K, et al. J Clin Oncol 2024 (postMONARCH primary). https://unifind.unisr.it/resource/item/236996
    Fan Y, et al. OptiTROP-Breast01 final OS. ESMO 2026, 4639RO.
    OptiTROP-Breast01 phase III publication (2025). https://cancer.fr/professionnels-de-sante/veille/nota-bene-cancer/bulletin-n-640/sacituzumab-tirumotecan-in-previously-treated-metastatic-triple-negative-breast-cancer-a-randomized-phase-3-trial
    Liu X, et al. SWITCH. ESMO 2026, 4RO.
Unknown's avatar

Published by Rodrigo Arrangoiz MS, MD, FACS, FSSO

My name is Rodrigo Arrangoiz I am a breast surgeon/ thyroid surgeon / parathyroid surgeon / head and neck surgeon / surgical oncologist that works at Center for Advanced Surgical Oncology in Miami, Florida. I was trained as a surgeon at Michigan State University from (2005 to 2010) where I was a chief resident in 2010. My surgical oncology and head and neck training was performed at the Fox Chase Cancer Center in Philadelphia from 2010 to 2012. At the same time I underwent a masters in science (Clinical research for health professionals) at the University of Drexel. Through the International Federation of Head and Neck Societies / Memorial Sloan Kettering Cancer Center I performed a two year head and neck surgery and oncology / endocrine fellowship that ended in 2016. Mi nombre es Rodrigo Arrangoiz, soy cirujano oncólogo / cirujano de tumores de cabeza y cuello / cirujano endocrino que trabaja Center for Advanced Surgical Oncology en Miami, Florida. Fui entrenado como cirujano en Michigan State University (2005 a 2010 ) donde fui jefe de residentes en 2010. Mi formación en oncología quirúrgica y e n tumores de cabeza y cuello se realizó en el Fox Chase Cancer Center en Filadelfia de 2010 a 2012. Al mismo tiempo, me sometí a una maestría en ciencias (investigación clínica para profesionales de la salud) en la Universidad de Drexel. A través de la Federación Internacional de Sociedades de Cabeza y Cuello / Memorial Sloan Kettering Cancer Center realicé una sub especialidad en cirugía de cabeza y cuello / cirugia endocrina de dos años que terminó en 2016.

Leave a comment