Amivantamab

Mesenchymal-epithelial transition factor (MET) is a receptor with tyrosine kinase activity expressed on epithelial cells that, upon signalling, dimerizes and activates downstream pathways that signal cell division. The Epidermal Growth Factor Receptor (EGFR) is a transmembrane protein with tyrosine kinase activity that can further activate downstream pathways that signal cell division, survival, and angiogenesis. Patients with NSCLC with exon 20 insertion mutations in EGFR do not respond to tyrosine kinase inhibitors, and are generally treated with platinum-based therapy. Exon 20 insertion mutations in EGFR also lead to conformational changes that activate EGFR.

Amivantamab targets both EGFR and MET, preventing ligands from binding to the receptors, blocking signalling, marking the cancerous cells for antibody-dependant cellular cytotoxicity by natural killer cells, and allowing macrophages to perform trogocytosis.

Amivantamab's binding to the EGFR H epitope shares some of the same amino acids that cetuximab binds to.

Amivantamab's binding to the alpha chain of MET stabilizes the Sema domain loop 1 to 2 in a position 6 Angstroms away from the position it would be in under normal binding, preventing its interaction with the hepatocyte growth factor's (HGF) beta chain. Another smaller conformational change in the MET Sema domain loop 1 to 3 also contributes to preventing the interaction of the MET Sema domain with HGF's beta chain. HGF is no longer able to bind to MET, preventing downstream signalling.

Amivantamab's Fc portion contains 90% less fucose than normal antibodies, allowing for increased binding to the FcγRIIIa region. Binding of the Fc portion of Amivantamab signals the complement system and innate immune system to target the bound cells for complement-dependent cytotoxicity, antibody-dependent cell-mediated cytotoxicity, and antibody-dependent cellular phagocytosis. Binding of amivantamab to the Fc receptor also leads to and increase in levels of IFNγ.

Amivantamab also significantly downregulates the expression of EGFR and MET on NSCLC cell surfaces, further reducing downstream signalling. EGFR and MET on the cell surface are internalized, and possibly degrading by fusing endosomes with lysosomes. Alternatively, EGFR and MET are the subjects of monocyte-dependent trogocytosis. Trogocytosis allows monocytes to internalize and break down EGFR and MET from the NSCLC cells without cytotoxicity, downmodulating EGFR and MET receptors.