EGFR exon 19 deletions and exon 21 mutations, and HER2 amplification and/or overexpression, are predictive of response to matched molecularly targeted therapies that have greatly improved patient outcomes. However, insertion mutations in exon 20 of either EGFR or HER2 generally do not confer sensitivity to these therapies. In this Review, the authors discuss the prevalence of EGFR and HER2 exon 20 insertions across cancers, their biology and detection, and associated responses to current molecularly targeted therapies and immunotherapies. In addition, they focus on new therapeutic strategies that are being developed to target tumours driven by these non-classic EGFR and HER2 alterations.
- Alex Friedlaender
- Vivek Subbiah
- Alfredo Addeo
