Effectiveness and safety of amivantamab in EGFR exon 20 insertion (E20I) mutations in non-small cell lung cancer (NSCLC).

Background: In non-small cell lung cancer (NSCLC), the epidermal growth factor receptor (EGFR) mutation is a representative oncogenic driver mutation. Only about 12% of EGFR mutation patients have the exon 20 insertion mutation, which is the third most frequent mutation among EGFR mutation NSCLC. Amivantamab, an EGFR and MET proto-oncogene, receptor tyrosine kinase (MET) bispecific antibody, was approved for NSCLC patients with the EGFR exon 20 insertion (E20I) mutation. In this study, we described the real-world, single-center efficacy and safety data of amivantamab in E20I mutation patients. Methods: This study included metastatic NSCLC patients with EGFR E20I mutations. From January 2018 to June 2022, patients with EGFR E20I mutations who were treated with amivantamab were analyzed at Samsung Medical Center as part of the clinical trial or the early access program (EAP). We collected the patients' characteristics [age, sex, smoking history, location of mutation, sites of metastasis, programmed death-ligand 1 (PD-L1) expression status, etc.] and analyzed progression-free survival (PFS) and overall survival (OS) stratified by PD-L1 expression status, co-mutation such as tumor protein p53 (TP53), and metastasis sites. Results: A total of 42 patients were analyzed, of which 16 patients were enrolled in the phase 1 study, and 26 patients received amivantamab through EAP. There were 14 (33%) patients with partial remission, 18 (43%) patients with stable disease, and 10 (24%) patients with disease progression. The objective response rate (ORR) was 33%, and the disease control rate (DCR) was 76%. PFS was analyzed by dividing the near and far loop for 31 patients whose mutation location was known. The two groups had no statistically significant difference in PFS [median (range): 11.8 (2.3-21.3) Conclusions: The efficacy of amivantamab was confirmed for the real-world population for EGFR E20I-mutated NSCLC. PD-L1 status could be a poor predictive factor, which should be further validated.