Roche has received FDA approval for the PATHWAY HER2 (4B5) test as a companion diagnostic to identify biliary tract cancer (BTC) patients who may benefit from HER2-targeted therapy with ZIIHERA (zanidatamab-hrii). This marks a significant advancement in personalized medicine for BTC, a cancer with limited treatment options and poor prognosis.
The PATHWAY HER2 (4B5) test is designed to assess HER2 protein expression in BTC tissue samples. HER2, a receptor protein, is a known predictive biomarker in various cancers, including BTC. The test helps determine if a patient's tumor expresses HER2 at a level that would likely respond to HER2-targeted therapies like ZIIHERA.
Addressing Unmet Needs in Biliary Tract Cancer
Biliary tract cancer accounts for approximately 3% of all gastrointestinal cancers in the United States. The prognosis for BTC patients is poor, with a five-year overall survival rate of only 19% for localized disease and 3% for metastatic disease. This is largely due to the lack of early detection methods and the aggressive nature of the disease. Until now, there has been no FDA-approved and validated HER2 test to identify eligible BTC patients for HER2-targeted therapies.
"This test is a step forward in furthering access to personalised medicine," said Jill German, Head of Pathology Lab at Roche Diagnostics. "The prognosis for patients diagnosed with BTC is poor, as very few treatment options exist. Now, these patients have access to the first standardised test that could make them eligible for targeted therapy, potentially improving clinical outcomes."
The Role of PATHWAY HER2 (4B5) in Treatment Decisions
The PATHWAY HER2 (4B5) test is performed on formalin-fixed paraffin-embedded (FFPE) tumor tissue using immunohistochemistry (IHC). The test utilizes the VENTANA BenchMark slide staining instrument, ensuring standardized and reliable results. The assay 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 semi-automated IHC methods. The Roche HER2 (4B5) clone achieves consistently high proficiency assessment scores compared to other clones and demonstrates high concordance with HER2 FISH, empowering laboratories to employ the most widely adopted and reliable HER2 IHC primary antibody.
The test's results, in conjunction with other clinical and pathological information, help oncologists determine whether a patient with previously-treated, unresectable or metastatic BTC is likely to respond to ZIIHERA, the first FDA-approved treatment for adults with this specific type of HER2-positive biliary tract cancer (IHC 3+).
Expanding the Utility of PATHWAY HER2 (4B5)
Previously, the PATHWAY HER2 (4B5) test was indicated for identifying breast cancer patients eligible for HER2-targeted treatments like Herceptin, KADCYLA, or ENHERTU. This new FDA approval significantly expands the test's clinical utility, providing a standardized and reliable method for identifying BTC patients who may benefit from HER2-targeted therapy. The assay forms an important part of Roche's comprehensive gastrointestinal cancer solutions portfolio, which is aimed at driving diagnostic certainty for life-changing decisions in cancer care.
