<scp>MET</scp> Enhances Amivantamab Binding to <scp>EGFR</scp> and Antibody‐Dependent Cellular Toxicity

Amivantamab is a bispecific antibody against epidermal growth factor receptor (EGFR) and MET that has been approved for nonsmall cell lung cancer (NSCLC) with EGFR exon 20 insertion mutations and common EGFR mutations, such as exon 19 deletion and L858R. MET has attracted attention as a therapeutic target for lung cancer; however, its role in EGFR binding and amivantamab-induced antibody-dependent cellular toxicity (ADCC) remains unclear. We used high-speed atomic force microscopy (HS-AFM) to observe the real-time binding of amivantamab to the EGFR-extracellular domain (ECD) and MET-ECD and visualized the binding of amivantamab to the EGFR domain 3 and MET Sema domain. Furthermore, we observed the trimer comprising amivantamab bound to EGFR and MET. Western blot analysis of the gel filtration fractions revealed that the MET-ECD enhanced the binding of amivantamab to the EGFR-ECD, which promoted trimer formation. Moreover, amivantamab-induced mononuclear cell-mediated ADCC in NSCLC cells with common EGFR mutations. ADCC activity was positively correlated with EGFR expression in tumor cells. Studies using MET-knockout NSCLC cells revealed that MET enhanced ADCC activity with low concentrations of amivantamab. Thus, MET augments amivantamab binding to EGFR and augments ADCC activity at low amivantamab concentrations. These results indicate that binding to MET contributes to the increased efficacy of amivantamab in NSCLC with common EGFR mutations.