Dr Debra Patt on Capturing the HER2-Low Population

Understanding that patients who are HER2-low are different from patients who are HER2-positive and -negative means having the right way to evaluate and identify these patients, explained Debra Patt, MD, PhD, MBA, executive vice president of Texas Oncology.

Transcript

Given the findings of DESTINY-Breast04, how can we better evaluate HER2 status to make treatment of HER2-low actionable and accurate?

I think that we need to make sure that we're capturing the HER2-low population. What DESTINY-Breast04 showed us is that among HER2-low patient populations with advanced breast cancer, there's a survival benefit from being treated with trastuzumab deruxtecan in comparison to chemotherapy. So, we need to make sure that we're identifying this HER2-low patient population.

It comprises about 55% of our advanced breast cancer patients. And we need to make sure that IHC [immunohistochemistry] is being done by pathology. Also, IHC is a little bit tricky and can have interoperator variability. So, we need to make sure that we work with our pathologists to identify those that are IHC1+, IHC2+ and FISH [fluorescence in situ hybridization]-negative. This means working closely with our pathologist to identify this patient population.

Also, in patients with advanced breast cancer who frequently have metastatic disease to the bone and may have bone biopsies that undergo decalcification, we need to recognize some of the limitations of that decalcification process on the sensitivity of HER2 evaluation and think about how we investigate each and every patient for what they might benefit from.