Human epidermal growth factor receptor 2 kinase domain exon 20 insertion mutants (HER2 exon 20 ins)

Human epidermal growth factor receptor 2 (HER2) kinase domain exon 20 insertion mutants are oncogenic drivers found in approximately 2-4% of non-small cell lung cancers (NSCLC) (Nature Medicine, 2018). These mutations, such as the common YVMA insertion, occur within the kinase domain and lead to a narrowed ATP-binding pocket and constitutive, ligand-independent activation of downstream signaling pathways including PI3K/AKT and MEK/ERK (Cancer Discovery, 2021). Unlike HER2 amplification seen in breast cancer, these specific insertions create a unique structural conformation that renders the receptor resistant to many first-generation tyrosine kinase inhibitors (TKIs) (Journal of Thoracic Oncology, 2020). Therapeutic strategies have shifted toward antibody-drug conjugates (ADCs) like trastuzumab deruxtecan, which was FDA-approved in 2022 for this indication, and novel TKIs designed to fit the altered binding pocket (FDA, 2022). Identifying these mutations requires high-sensitivity testing such as next-generation sequencing (NGS), as they are often missed by protein-based assays like immunohistochemistry (Clinical Cancer Research, 2019).

Other names

ERBB2 exon 20 insertionHER2 YVMA mutationHER2 kinase domain mutationsERBB2 kinase domain insertionsNeu exon 20 insertion

Drugs targeting these mutants typically function as either small-molecule tyrosine kinase inhibitors (TKIs) that bind to the ATP-binding site of the mutated kinase domain to inhibit phosphorylation, or as antibody-drug conjugates (ADCs) that utilize the HER2 receptor for targeted delivery of cytotoxic agents (Nature Reviews Clinical Oncology, 2022).