A score of 1 1 to 4 was given, where 1?= no visible band, 2?= slightly visible band, 3?= phosphorylation comparable with poor agonist (MET B IgG1), and 4?= phosphorylation level much like positive controls (MET A and MET 5D5 IgG1 mAbs). Proliferation assays Test molecules were added to H1975, KP4 (Riken Cell lender, RCB1005), or NCI-H441?cells plated at 5000 or 10,000 (KP4) cells/well in 96-well plates. the anti-MET Fab of amivantamab bound to MET was solved, and the conversation between the two molecules in atomic details was elucidated. Amivantamab antagonized the hepatocyte growth factor (HGF)-induced signaling by binding to MET Sema domain name and thereby blocking HGF -chainSema engagement. The amivantamab EGFR epitope was mapped to EGFR domain name III and residues K443, K465, I467, and S468. Furthermore, amivantamab showed superior antitumor activity over small molecule EGFR and MET inhibitors in the HCC827-HGF model. Based on its unique mode of action, amivantamab may provide benefit to patients with malignancies associated with aberrant EGFR and MET signaling. gene, mainly L858R mutation and exon 19 deletions, result in ligand-independent activation of the EGFR kinase activity (5). Tyrosine kinase inhibitors (TKIs) targeting EGFR are the standard of care for patients with EGFR-mutated NSCLC (6, 7); Sulfabromomethazine however, many patients will acquire resistance to TKIs (8, 9). In addition, MET pathway activation increased expression of receptor or ligand is frequently implicated in TKI resistance (10, 11, 12). Treatment strategies targeting both receptors using a combination of single-agent EGFR and MET inhibitors do not cover the wide range of resistance mechanisms (13, 14), hence the need for novel approaches to overcome resistance and to accomplish clinical benefit. Simultaneous engagement of both EGFR and MET, through a bispecific antibody (BsAb), is usually a potential strategy to overcome resistance and accomplish greater efficacy (15). Identification of an antagonist antibody targeting MET can be challenging Sulfabromomethazine as the mechanism of action depends on the valency of the antibody for the tumor target antigen. Such antibodies are referred to as anti-MET, which modulate the activity of c-Met, also called tyrosine-protein kinase Met or hepatocyte growth factor receptor, which is a protein encoded by the gene. Upon ligand binding, MET dimerizes and initiates signaling pathway activation (16). Therefore, antibodies that induce dimerization of MET may have agonistic activity (17), although antagonistic bivalent MET monoclonal antibodies (mAbs) have been reported (18, 19). An antibody with a monovalent anti-MET binding arm may prevent MET dimerization-based agonism (20, 21). However, an antibody with this house, such as onartuzumab, did not have a favorable clinical profile (22, 23, 24), likely due to (1) failure to induce Fc-mediated effector functions; (2) reduced MET downmodulation internalization by monovalent molecules; and (3) solely targeting MET, which may trigger development of resistance oncogenic Sulfabromomethazine EGFR signaling. Thus, we embarked on discovering a molecule with a different molecular format and unique epitope to improve efficacy. BsAbs that target EGFR and MET through unique epitopes and architecture have had varying clinical results (25, 26, 27, 28). To maximize inhibition of EGFR and MET pathways, we aimed at discovering a novel BsAb that combines all the previously described mechanisms of action for EGFR and MET antibodies but without inducing receptor dimerization and activation. The BsAb would have two binding arms: one monovalent arm that engages EGFR and the other monovalent arm that engages MET. To enable the selection of the optimal bispecific molecule, we screened a panel of BsAbs in an empirical approach that led to the selection of amivantamab (JNJ-61186372), an EGFR? MET BsAb that Rabbit Polyclonal to HRH2 has activity in EGFR TKI-resistant NSCLC models (29). Here, we describe a versatile selection strategy, provide structural insights in the binding of amivantamab, and present novel functional antitumor data. Results Parental antibody selection criteria and procedure for generating BsAbs The controlled Fab-arm exchange (cFAE) platform was used to generate a panel of 40 (5 MET parental mAbs with 8 EGFR parental mAbs) MET? EGFR BsAbs in the DuoBody format (30) (Fig.?1represents an array of five IgG1 anti-MET and one control anti-gp120 (b12) mAbs with the leucine to phenylalanine substitution at position 405 (F405L). The represents an array of eight IgG1 anti-EGFR and one control anti-gp120 mAbs with the lysine to arginine substitution at position 409 (K409R). Upon individual cell-culture growth, each mAb was purified using protein A chromatography. The.