FDA Approves Companion Diagnostic for Trastuzumab in HER2+ Breast Cancer


The FDA has approved the new VENTANA HER2 Dual ISH DNA Probe Cocktail test for use as a companion diagnostic for trastuzumab and to detect HER2 mutations in patients with breast cancer.

The FDA has approved the new VENTANA HER2 Dual ISH DNA Probe Cocktail test for use as a companion diagnostic for trastuzumab (Herceptin) and to detect HER2 mutations in patients with breast cancer, according to an announcement from Roche, the developer of the assay.1

The novel assay was developed to produce results within the same day, which is faster than some of the other confirmatory testing methods for HER2 that are currently available, according to the pharmaceutical company. Moreover, assay results can be read using light microscopy, which is an approach that eliminates the need for a specialized fluorescence microscope.

“With this new VENTANA HER2 Dual ISH assay, Roche continues to deliver on its commitment to advance personalized healthcare,” Thomas Schinecker, CEO of Roche Diagnostics, stated in a press release. “Quick test results are crucial in the fight against cancer and by delivering crucial information on treatment options for [patients with] breast cancer faster, this assay will aid clinicians in their therapeutic decisions.”

The fully automated, ready-to-use assay is optimized with new oligo probes that allows for the delivery of “clear, confident reads” with regard to identifying HER2 mutational status.2 Moreover, the test allows for elucidation within the context of tissue morphology, it detects tumor heterogeneity, and it yields an archivable result, according to Roche. The assay has been shown to assist in the identification of patients with either breast or gastric cancer who are eligible to receive HER2-targeted therapies.

Several guidelines, including those issued by the National Comprehensive Cancer Network, the College of American Pathologists, and ASCO, advise for the examination of HER2 protein expression via an immunohistochemistry test for breast cancer specimens.3,4 A reflex test using in situ hybridization should then be done, depending on the IHC results.

“The VENTANA HER2 Dual ISH DNA Probe Cocktail is intended to determine HER2 gene status by enumeration of the ratio of the HER2 gene to Chromosome 17 by light microscopy,” according to Roche. The assay was developed for utilization on formalin-fixed, paraffin-embedded human tissue specimens from patients with breast or gastric cancer with the VENTANA Silver ISH DNP Detection Kit and the VENTANA Red ISH DIG Detection Kit, on the BenchMark IHC/ISH instruments.

With the brightfield microscopy technology, a fluorescent microscope/oil and a darkroom are no longer needed. Additionally, results from the test can be assessed at the same time as H&E and other breast panel markers on the same case, allowing for easier comparison.

In April 2019, the assay was launched in Europe, the Middle East, Africa, Latin America, and Asia Pacific.5


  1. FDA approves Roche’s new VENTANA HER2 Dual ISH test as companion diagnostic to identify breast cancer patients eligible for targeted therapy. Roche. News release. July 29, 2020. Accessed July 29, 2020. https://bit.ly/2X8MGxC.
  2. VENTANA HER2 Dual ISH DNA Prob Cocktail assay (CE IVD). Roche website. Accessed July 29, 2020. https://bit.ly/2X9YhN4.
  3. Wolff AC, Hammond MEH, Allison KH, et al. Human Epidermal Growth Factor Receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline focused update. J Clin Oncol. 2018;36(20):2105-2122. doi:10.1200/JCO.2018.77.8738
  4. NCCN Guidelines version 1.2018. NCCN Clinical Practice Guidelines in Oncology Breast Cancer. NCCN.org. Accessed July 29, 2020.
  5. Roche launches new VENTANA HER2 Dual ISH companion diagnostic test for breast cancer and gastric cancer patients eligible for targeted therapy. Roche. April 23, 2019. Accessed July 29, 2020. https://bit.ly/2Dc65GV.
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Kari Wisinski, MD, Endowed Professor of Hematology and Oncology, chief, Division of Hematology, Medical Oncology, and Palliative Care, Department of Medicine, University of Wisconsin (UW) School of Medicine and Public Health; associate director, Clinical Research, co-lead, Breast Cancer Disease Oriented Team, UW Carbone Cancer Center
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Jane L. Meisel, MD, Emory University