Rapid oral abstract session: Metastatic breast cancer

For this highlight video, Dr Laure-Anne Teuwen, medical oncologist at University Hospital Antwerp, selected four studies on metastatic breast cancer presented during the rapid oral session on metastatic breast cancer at ASCO 2026. 

The PALMARES-2 study is a large Italian real-world cohort study evaluating continuation of first-line endocrine therapy plus CDK4/6 inhibition beyond disease progression in patients with HR-positive, HER2-negative advanced breast cancer.¹ Among more than 2,200 patients with documented progression, 19% continued treatment beyond progression, often combined with locoregional therapy. Patients selected for this strategy tended to have more favourable characteristics, including younger age, higher ER and PgR expression, more bone metastases and fewer liver metastases. Median real-world progression-free survival beyond progression was 10.5 months. Better ECOG performance status, lower Ki-67, higher ER/PgR expression and the use of locoregional therapy were independently associated with longer benefit. The retrospective design and absence of centralised radiological review are important limitations.

A US retrospective cohort study explored the impact of food access and poverty on ctDNA profiles and clinical outcomes in metastatic breast cancer.² The analysis included 851 patients who had undergone Guardant360 ctDNA testing. Almost half of the patients lived in low food access areas, while a smaller subgroup lived in areas with both low income and low food access. Low food access was associated with a higher frequency of RTK/RAS pathway alterations, while low-income and low-access areas were associated with more CCNE1 copy number variations. Patients living in low-access areas had shorter overall survival than those with high food access. Although limited by its retrospective design and the use of area-level rather than individual-level food insecurity data, the study highlights food access as a potentially important social determinant of tumour biology and outcomes in metastatic breast cancer.

Exploratory biomarker analyses from ASCENT-03 and ASCENT-04 evaluated whether the benefit of sacituzumab govitecan in first-line metastatic triple-negative breast cancer differed according to Trop-2 expression, tumour BRCA status or HER2 expression.^3,4 ASCENT-03 evaluated sacituzumab govitecan versus chemotherapy in patients who were not candidates for PD-1/PD-L1 inhibitors, while ASCENT-04 evaluated sacituzumab govitecan plus pembrolizumab versus chemotherapy plus pembrolizumab in PD-L1-positive disease. Across both studies, progression-free survival benefit was maintained across Trop-2 expression quartiles, tumour BRCA wild-type and mutated subgroups, and HER2 IHC 0 and HER2-low subgroups. These findings support the use of sacituzumab govitecan-based first-line therapy across clinically relevant biomarker-defined subgroups and suggest that routine Trop-2 testing is not required to select patients for this Trop-2-directed antibody-drug conjugate. As these were exploratory analyses with small numbers in some subgroups, the results should be interpreted descriptively.