The European Society of Medical Oncologists (ESMO) hosted its 2025 ESMO Breast Cancer meeting from May 14th to 17th in Munich, Germany. Attended by oncology professionals from across the globe, this meeting presents the latest innovations and research in breast cancer care. We’ve compiled some of the key findings discussed at this conference.
As a reminder, neoadjuvant refers to a therapy or treatment received BEFORE surgery to treat your cancer. An adjuvant treatment occurs after the initial treatment–most likely a surgery. Progression-free survival is the period of time after starting treatment that patients live without the cancer getting worse or spreading.
Results from the EMBER-3 trial show abemaciclib and imlunestrant offer benefits for people diagnosed with advanced-stage, estrogen receptor-positive, HER2-negative breast cancer even after disease progression. According to one of the studies, this is significant because it’s the first Phase III trial to demonstrate a benefit of this combined approach after progression for a patient on a CDK4/6 inhibitor therapy. Additionally, it’s an oral, targeted therapy option for patients, including those with ESR1 and PI3K mutations. Imlunestrant is awaiting FDA approval for breast cancer.
Two studies reveal that some patients with early-stage ER+/HER2– breast cancer can forgo chemotherapy and instead treat their disease with ribociclib and endocrine therapy. More data is needed to determine how clinicians can utilize gene expression assays, like the Oncotype DX assay, to guide treatment decisions in patients. These studies are significant as they mean it might be possible for some patients with early-stage breast cancer to avoid chemotherapy and its related side effects.
Recent findings highlight the importance of circulating tumor DNA (ctDNA) in managing breast cancer, specifically for detecting ESR1 mutations. A secondary analysis of the PADA-1 trial suggests there may be a specific window to test for ESR1 mutations during treatment. Additionally, the I-SPY 2 trial findings reveal that ctDNA can help predict metastatic recurrence in early-stage breast cancer. These studies are significant because they lend data to the conversation around ctDNA, suggesting this technology might be able to inform treatment decisions that improve outcomes.
A new study showed that low levels of tumour infiltrating lymphocytes (TILs- a type of immune cell) are associated with the risk of triple-negative breast cancer (TNBC) coming back after treatment, even when other factors favor a good prognosis. Higher levels of TILs, which help fight cancer, were associated with a lower risk of recurrence of TNBC. This is significant as it may inform the monitoring approach for TNBC patients post-chemotherapy with no evidence of disease.
A new experimental drug, izalontamab brengitecan (Iza-Bren), showed promising results in metastatic HER2-negative and HER2-low breast cancer patients who had already undergone at least three previous lines of therapy. This phase I study is promising because it could help patients who have few or no treatment options available.
Researchers are looking for targeted therapies for HER2-positive and HER2-low metastatic breast cancer patients whose disease has progressed after multiple previous treatments. Data shows chemotherapy plus zanidatamab (Ziihera) has a manageable safety profile and shows preliminary antitumor activity for this subgroup. This is significant as it may represent a new treatment option for patients with mBC who have already progressed on a HER2-targeted therapy. Zanidatamab is already FDA-approved for the treatment of HER2+ biliary tract cancer.
Long-term follow-up from the APHINITY trial shows adding adjuvant pertuzumab to standard adjuvant chemotherapy and trastuzumab improved overall survival at 11.3 years for patients with early HER2+ lymph node-positive operable breast cancer. This is significant as it demonstrates a clinically meaningful survival benefit of this treatment for patients who have a high risk of recurrence.
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