The U.S. Food and Drug Administration (FDA) has approved a label expansion for the PATHWAY anti-HER2/neu (4B5) Rabbit Monoclonal Primary Antibody to identify patients with hormone receptor (HR)-positive, HER2-ultralow metastatic breast cancer who may be eligible for treatment with fam-trastuzumab deruxtecan-nxki (T-DXd; Enhertu). T-DXd is a specifically engineered HER2-directed antibody-drug conjugate.
Until the introduction of HER2-low status in 2022, HER2 status was categorized as either “positive” or “negative” based on the level of HER2 expression. The PATHWAY HER2 (4B5) test has now received approval to identify a new patient population designated as "HER2-ultralow,” which refers to patients who have very low levels of HER2 expression—even lower than the existing HER2-low category.
To determine a patient’s HER2 status, pathologists score the level of HER2 receptor protein expressed in breast cancer tissue samples. The PATHWAY HER2 (4B5) test was used as part of the DESTINY-Breast06 trial, which showed a median progression-free survival of 13.2 months with T-DXd compared with 8.1 months with the standard of care (chemotherapy) in the overall trial population of patients with HER2-low and HER2-ultralow metastatic breast cancer. An exploratory analysis showed the results were consistent between patients with HER2-low and HER2-ultralow expression.
The FDA approval of the new HER2-ultralow indication expands on the intended use for the PATHWAY anti-HER2 (4B5) test, proven to deliver timely, clear, and confident results.
More About the PATHWAY anti-HER2/neu (4B5) Rabbit Monoclonal Antibody
The prediluted PATHWAY anti-HER2/neu (4B5) Rabbit Monoclonal Primary Antibody, used in combination with the fully automated BenchMark IHC/ISH slide staining instrument, standardizes all immunohistochemistry (IHC) processes from baking through staining and reduces the possibility of human error. It also minimizes inherent variability resulting from individual reagent dilution and other processes found in manual and semiautomated IHC methods. The Roche HER2 (4B5) clone reportedly achieves consistently high proficiency assessment scores compared with other clones and demonstrates high concordance with HER2 fluorescence in situ hybridization.
