EGFR and ERBB2 Exon 20 Insertion Mutations in Chinese Non-small Cell Lung Cancer Patients: Pathological and Molecular Characterization, and First-Line Systemic Treatment Evaluation.

Background: Data from studies looking at both EGFR and ERBB2 exon 20 insertion mutations (-20ins) in the same cohort of patients with non-small cell lung cancer (NSCLC) are limited.

Objective: The purpose of this study was to analyze EGFR/ERBB2-20ins in all-stage NSCLC patients to reveal their histological and molecular features, and to retrospectively evaluate the results of first-line real-world systemic treatments in patients with advanced-stage disease.

Patients and methods: We collected 13,920 formalin-fixed paraffin-embedded NSCLC specimens. Clinicopathological features were recorded and DNA-based next-generation sequencing was performed. First-line systemic treatment data were obtained via chart review.

Results: In total, 414 (2.97%) EGFR-20ins cases and 666 (4.78%) ERBB2-20ins cases were identified. Both were more common in women, non-smokers, and patients with adenocarcinoma. The incidence of EGFR/ERBB2-20ins in adenocarcinoma is inversely proportional to the degree of invasion; 77 and 26 variants were detected in EGFR-20ins and ERBB2-20ins cases, respectively. The most common concurrently mutated genes were TP53 and RB1. In invasive adenocarcinoma, lepidic components were more common in EGFR/ERBB2-20ins-alone cases than in those with other concurrent mutated genes. In EGFR-/ERBB2-20ins patients, there was no significant difference in progression-free survival (PFS) or treatment response to first-line systemic treatments in this study. There was no significant difference in PFS or treatment response among patients with different EGFR/ERBB2-20ins variants and those with or without concurrent mutated genes.

Conclusions: EGFR/ERBB2-20ins is more common in early lung adenocarcinoma. EGFR-20ins had more variants. In both cohorts, the results for first-line systemic treatments showed no significant difference.