Clinical and Genomic Features of HER2 Exon 20 Insertion Mutations and Characterization of HER2 Expression by Immunohistochemistry in East Asian Non-Small-Cell Lung Cancer.

The incidence of mutations is 3.1% in East Asian nonsquamous NSCLC. exon 20 insertion-mutated tumors appear genomically distinct from uncommon (nonexon 20 insertion) mutations, the latter demonstrating higher TMB, co-occurring drivers, and predominant nonaging mutational signature. The therapeutic implications of the genomic and clinical features of -mutated NSCLC warrant further investigation.