Interpreting HER2 Results on Reports and Why the Tyrosine Kinase Domain Matters

The faculty discuss why HER2 results are confusing to read. The moderator separates HER2 protein expression, amplification, and mutation. He notes trastuzumab deruxtecan’s tissue-agnostic approval, that amplification is still unclear in lung cancer but may matter at acquired resistance, and that mutations fall mostly in the tyrosine kinase domain (TKD). One panelist says AI tools now help clinicians interpret results, and that oral TKIs work well for TKD mutations while an ADC may suit mutations elsewhere, though the evidence is not yet fully settled. Another panelist describes teaching trainees to tell mutation from amplification and overexpression and recalls providing feedback to companies for more universal report language.