How do you differentiate between ERBB2 mutation vs HER2 overexpression testing when selecting patients for tumor-agnostic therapy?

This distinction is critical. HER2 protein overexpression (IHC ± ISH) underpins T-DXd’s tumor-agnostic approval. ERBB2 mutations define a different subset that perhaps may have better responses to HER2 TKIs that are in development rather than ADCs. In other words, a genomic alteration in ERBB2 does ...

In my practice, I recommend next-generation sequencing to assess for actionable genomic alterations, as well as HER2 IHC, for patients with advanced/metastatic cancer.

In my practice, I recommend NGS and HER2 IHC. This opens up new therapeutic hope since the latter is an agnostic biomarker for treating solid tumors with HER2 ADC (T-DXd).