Landscape of HER2-low metastatic breast cancer (MBC): results from the Austrian AGMT_MBC-Registry

BACKGROUND: About 50% of all primary breast cancers show a low-level expression of HER2 (HER2-low), defined as immunohistochemically 1+ or 2+ and lack of HER2 gene amplification measured by in situ hybridization. This low HER2 expression is a promising new target for antibody–drug conjugates (ADCs)...

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Detalles Bibliográficos
Autores principales: Gampenrieder, Simon Peter, Rinnerthaler, Gabriel, Tinchon, Christoph, Petzer, Andreas, Balic, Marija, Heibl, Sonja, Schmitt, Clemens, Zabernigg, August Felix, Egle, Daniel, Sandholzer, Margit, Singer, Christian Fridolin, Roitner, Florian, Hager, Christopher, Andel, Johannes, Hubalek, Michael, Knauer, Michael, Greil, Richard
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2021
Materias:
Research Article
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8670265/
https://www.ncbi.nlm.nih.gov/pubmed/34906198
http://dx.doi.org/10.1186/s13058-021-01492-x
Descripción
Sumario:BACKGROUND: About 50% of all primary breast cancers show a low-level expression of HER2 (HER2-low), defined as immunohistochemically 1+ or 2+ and lack of HER2 gene amplification measured by in situ hybridization. This low HER2 expression is a promising new target for antibody–drug conjugates (ADCs) currently under investigation. Until now, little is known about the frequency and the prognostic value of low HER2-expression in metastatic breast cancer (MBC). PATIENTS AND METHODS: The MBC-Registry of the Austrian Study Group of Medical Tumor Therapy (AGMT) is a multicenter nationwide ongoing registry for MBC patients in Austria. Unadjusted, univariate survival probabilities of progression-free survival (PFS) and overall survival (OS) were calculated by the Kaplan–Meier method and compared by the log-rank test. Multivariable adjusted hazard ratios were estimated by Cox regression models. In this analysis, only patients with known HER2 status and available survival data were included. RESULTS: As of 11/15/2020, 1,973 patients were included in the AGMT-MBC-Registry. Out of 1,729 evaluable patients, 351 (20.3%) were HER2-positive, 608 (35.2%) were HER2-low and 770 (44.5%) were completely HER2-negative (HER2-0). Low HER2-expression was markedly more frequent in the hormone-receptor(HR)+ subgroup compared to the triple-negative subgroup (40% vs. 23%). In multivariable analysis, low HER2 expression did not significantly influence OS neither in the HR+ (HR 0.89; 95% CI 0.74–1.05; P = 0.171) nor in the triple-negative subgroup (HR 0.92; 95% CI 0.68–1.25; P = 0.585), when compared to completely HER2-negative disease. Similar results were observed when HER2 IHC 2+ patients were compared to IHC 1+ or 0 patients. CONCLUSION: Low-HER2 expression did not have any impact on prognosis of metastatic breast cancer in this real-world population. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13058-021-01492-x.

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