Clinical and molecular characteristics of epidermal growth factor receptor exon 20 insertion mutations in...

To evaluate the genomic and immune characteristics of non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutations from a retrospective dataset with molecular spectrum, tumor mutational burden (TMB), and programmed death-ligand 1 (PD-L1) expression, as well as to evaluate the efficacy of immune checkpoint inhibitors (ICIs).

A total of 283 patients with EGFR ex20ins mutations who were diagnosed with NSCLC at our hospital from August 2013 to September 2020 were enrolled in this single-center retrospective study.

Among the 283 patients with EGFR ex20ins mutations, 182 patients received next-generation sequencing (NGS) test, and 51 different subtypes of insertion variants were recorded. The most common mutations were A767_V769dup (21.4%), S768_D770dup (19.2%) and A763_Y764insFQEA (7.1%). The most common co-occurring mutations were EGFR amplification (37.9%), TP53 mutation (35.0%) and PIK3CA mutation (8.7%). PD-L1 status was available for 141 patients, and 75.9% (107/141) of these samples showed negative PD-L1 expression. In the 36 cases with TMB tested by NGS, the median TMB was 4.6 mutations/Mb. Then 12 patients received ICIs monotherapy or combination therapy. No severe adverse events were observed.

Low PD-L1 expression and TMB were observed in NSCLC patients harboring EGFR ex20ins mutations. Further investigations are needed to confirm the therapeutic sensitivity of ICIs in this subgroup of EGFR mutations.