Dr Abu Rous on the Timing of HER2 and MET Testing in NSCLC

"This is an evolving matter, especially after the two approvals that we recently got for patients with HER2 and MET overexpression. This is not a mutational testing, it's IHC testing, which is not done routinely for non small cell lung cancer. In my practice, I'm trying to test at progression."

Fawzi F Abu Rous, MD, a thoradic medical oncologist at Henry Ford Health, discussed evolving strategies for HER2 and MET testing in non–small cell lung cancer (NSCLC) in light of recent therapeutic approvals targeting these biomarkers.

He explained that current testing is performed using immunohistochemistry (IHC), rather than mutational analysis. Unlike more established biomarker assays in NSCLC, HER2 and MET IHC testing is not conducted routinely and may not be available through all laboratories, requiring clinicians to specifically request it. As a result, adoption into standard practice has been gradual.

The timing of testing remains an area of debate, with some clinicians testing at baseline and others incorporating testing later in the disease course, Abu Rous explained. In his own practice, he has adopted testing at the time of progression, particularly since there are limited data on whether HER2 or MET expression differs before and after immunotherapy. He emphasized that NSCLC is a heterogeneous disease, with tumor biology evolving over time, which supports reassessment of biomarker expression at key clinical decision points.

He further observed that in some patients, HER2 and MET expression patterns can change, while in others, expression remains stable. These observations underscore the need for additional research to define optimal testing strategies and to better understand the dynamics of biomarker expression in NSCLC.

As therapies targeting HER2 and MET become more widely integrated into treatment paradigms, refining the timing and consistency of testing will be essential to ensure appropriate patient selection and maximize therapeutic benefit, Abu Rous concluded.