Amivantamab, an Epidermal Growth Factor Receptor (EGFR) and Mesenchymal-epithelial Transition Factor (MET) Bispecific Antibody, Designed to Enable Multiple Mechanisms of Action and Broad Clinical Applications.

Substantial therapeutic advancements have been made in identifying and treating activating mutations in advanced non-small cell lung cancer (NSCLC); however, resistance to epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor (MET) inhibitors remains common with current targeted therapies. Amivantamab, a fully human bispecific antibody targeting EGFR and MET, is approved in the United States and other countries for the treatment of patients with advanced NSCLC with EGFR exon 20 insertion mutations, for whom disease has progressed on or after platinum-based chemotherapy. Preliminary efficacy and safety have also been demonstrated in patients with common EGFR- or MET-mutated NSCLC. Amivantamab employs 3 distinct potential mechanisms of action (MOAs) including ligand blocking, receptor degradation, and immune cell-directing activity, such as antibody-dependent cellular cytotoxicity and trogocytosis. Notably, efficacy with amivantamab does not require all 3 MOAs to occur simultaneously, broadening applicability by using diverse antitumor mechanisms. This review focuses on the molecular characteristics of amivantamab and its unique MOAs leading to in vitro and in vivo efficacy and safety in preclinical and clinical studies.

Discovery of amivantamab (JNJ-61186372), a bispecific antibody targeting EGFR and MET.

A bispecific antibody (BsAb) targeting the epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor (MET) pathways represents a novel approach to overcome resistance to targeted therapies in patients with non-small cell lung cancer. In this study, we sequentially screened a panel of BsAbs in a combinatorial approach to select the optimal bispecific molecule. The BsAbs were derived from different EGFR and MET parental monoclonal antibodies. Initially, molecules were screened for EGFR and MET binding on tumor cell lines and lack of agonistic activity toward MET. Hits were identified and further screened based on their potential to induce untoward cell proliferation and cross-phosphorylation of EGFR by MET via receptor colocalization in the absence of ligand. After the final step, we selected the EGFR and MET arms for the lead BsAb and added low fucose Fc engineering to generate amivantamab (JNJ-61186372). The crystal structure of the anti-MET Fab of amivantamab bound to MET was solved, and the interaction between the two molecules in atomic details was elucidated. Amivantamab antagonized the hepatocyte growth factor (HGF)-induced signaling by binding to MET Sema domain and thereby blocking HGF ß-chain-Sema engagement. The amivantamab EGFR epitope was mapped to EGFR domain 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 in vivo model. Based on its unique mode of action, amivantamab may provide benefit to patients with malignancies associated with aberrant EGFR and MET signaling.

Development of [89Zr]ZrDFO-amivantamab bispecific to EGFR and c-MET for PET imaging of triple-negative breast cancer.

BACKGROUND: Amivantamab is a novel bispecific antibody that simultaneously targets the epidermal growth factor receptor (EGFR) and the hepatocyte growth factor receptor (HGFR/c-MET) that are overexpressed in several types of cancer including triple-negative breast cancer (TNBC). Targeting both receptors simultaneously can overcome resistance to mono-targeted therapy. The purpose of this study is to develop 89Zr-labeled amivantamab as a potential companion diagnostic imaging agent to amivantamab therapy using various preclinical models of TNBC for evaluation. METHODS: Amivantamab was conjugated to desferrioxamine (DFO) and radiolabeled with 89Zr to obtain [89Zr]ZrDFO-amivantamab. Binding of the bispecific [89Zr]ZrDFO-amivantamab as well as its mono-specific "single-arm" antibody controls were determined in vitro and in vivo. Biodistribution studies of [89Zr]ZrDFO-amivantamab were performed in MDA-MB-468 xenografts to determine the optimal imaging time point. PET/CT imaging with [89Zr]ZrDFO-amivantamab or its isotype control was performed in a panel of TNBC xenografts with varying levels of EGFR and c-MET expression. RESULTS: [89Zr]ZrDFO-amivantamab was synthesized with a specific activity of 148 MBq/mg and radiochemical yield of ≥ 95%. Radioligand binding studies and western blot confirmed the order of EGFR and c-MET expression levels: HCC827 lung cancer cell (positive control) > MDA-MB-468 > MDA-MB-231 > MDA-MB-453. [89Zr]ZrDFO-amivantamab demonstrated bispecific binding in cell lines co-expressed with EGFR and c-MET. PET/CT imaging with [89Zr]ZrDFO-amivantamab in TNBC xenografted mice showed standard uptake value (SUVmean) of 6.0 ± 1.1 in MDA-MB-468, 4.2 ± 1.4 in MDA-MB-231, and 1.5 ± 1.4 in MDA-MB-453 tumors, which are consistent with their receptors' expression levels on the cell surface. CONCLUSION: We have successfully prepared a radiolabeled bispecific antibody, [89Zr]ZrDFO-amivantamab, and evaluated its pharmacologic and imaging properties in comparison with its single-arm antibodies and non-specific isotype controls. [89Zr]ZrDFO-amivantamab demonstrated the greatest uptake in tumors co-expressing EGFR and c-MET.

Amivantamab (JNJ-61186372), an Fc Enhanced EGFR/cMet Bispecific Antibody, Induces Receptor Downmodulation and Antitumor Activity by Monocyte/Macrophage Trogocytosis.

Small molecule inhibitors targeting mutant EGFR are standard of care in non-small cell lung cancer (NSCLC), but acquired resistance invariably develops through mutations in EGFR or through activation of compensatory pathways such as cMet. Amivantamab (JNJ-61186372) is an anti-EGFR and anti-cMet bispecific low fucose antibody with enhanced Fc function designed to treat tumors driven by activated EGFR and/or cMet signaling. Potent in vivo antitumor efficacy is observed upon amivantamab treatment of human tumor xenograft models driven by mutant activated EGFR, and this activity is associated with receptor downregulation. Despite these robust antitumor responses in vivo, limited antiproliferative effects and EGFR/cMet receptor downregulation by amivantamab were observed in vitro Interestingly, in vitro addition of isolated human immune cells notably enhanced amivantamab-mediated EGFR and cMet downregulation, leading to antibody dose-dependent cancer cell killing. Through a comprehensive assessment of the Fc-mediated effector functions, we demonstrate that monocytes and/or macrophages, through trogocytosis, are necessary and sufficient for Fc interaction-mediated EGFR/cMet downmodulation and are required for in vivo antitumor efficacy. Collectively, our findings represent a novel Fc-dependent macrophage-mediated antitumor mechanism of amivantamab and highlight trogocytosis as an important mechanism of action to exploit in designing new antibody-based cancer therapies.

Characterization of In Vivo Resistance to Osimertinib and JNJ-61186372, an EGFR/Met Bispecific Antibody, Reveals Unique and Consensus Mechanisms of Resistance.

Approximately 10% of non-small cell lung cancer (NSCLC) patients in the United States and 40% of NSCLC patients in Asia have activating epidermal growth factor receptor (EGFR) mutations and are eligible to receive targeted anti-EGFR therapy. Despite an extension of life expectancy associated with this treatment, resistance to EGFR tyrosine kinase inhibitors and anti-EGFR antibodies is almost inevitable. To identify additional signaling routes that can be cotargeted to overcome resistance, we quantified tumor-specific molecular changes that govern resistant cancer cell growth and survival. Mass spectrometry-based quantitative proteomics was used to profile in vivo signaling changes in 41 therapy-resistant tumors from four xenograft NSCLC models. We identified unique and tumor-specific tyrosine phosphorylation rewiring in tumors resistant to treatment with the irreversible third-generation EGFR-inhibitor, osimertinib, or the novel dual-targeting EGFR/Met antibody, JNJ-61186372. Tumor-specific increases in tyrosine-phosphorylated peptides from EGFR family members, Shc1 and Gab1 or Src family kinase (SFK) substrates were observed, underscoring a differential ability of tumors to uniquely escape EGFR inhibition. Although most resistant tumors within each treatment group displayed a marked inhibition of EGFR as well as SFK signaling, the combination of EGFR inhibition (osimertinib) and SFK inhibition (saracatinib or dasatinib) led to further decrease in cell growth in vitro This result suggests that residual SFK signaling mediates therapeutic resistance and that elimination of this signal through combination therapy may delay onset of resistance. Overall, analysis of individual resistant tumors captured unique in vivo signaling rewiring that would have been masked by analysis of in vitro cell population averages. Mol Cancer Ther; 16(11); 2572-85. ©2017 AACR.

Fc-mediated activity of EGFR x c-Met bispecific antibody JNJ-61186372 enhanced killing of lung cancer cells.

Epidermal growth factor receptor (EGFR) mutant non-small cell lung cancers acquire resistance to EGFR tyrosine kinase inhibitors through multiple mechanisms including c-Met receptor pathway activation. We generated a bispecific antibody targeting EGFR and c-Met (JNJ-61186372) demonstrating anti-tumor activity in wild-type and mutant EGFR settings with c-Met pathway activation. JNJ-61186372 was engineered with low fucosylation (<10 %), resulting in enhanced antibody-dependent cell-mediated cytotoxicity and FcγRIIIa binding. In vitro and in vivo studies with the single-arm EGFR or c-Met versions of JNJ-61186372 identified that the Fc-activity of JNJ-61186372 is mediated by binding of the anti-EGFR arm and required for inhibition of EGFR-driven tumor cells. In a tumor model driven by both EGFR and c-Met, treatment with Fc-silent JNJ-61186372 or with c-Met single-arm antibody reduced tumor growth inhibition compared to treatment with JNJ-61186372, suggesting that the Fc function of JNJ-61186372 is essential for maximal tumor inhibition. Moreover in this same model, downregulation of both EGFR and c-Met receptors was observed upon treatment with Fc-competent JNJ-61186372, suggesting that the Fc interactions are necessary for down-modulation of the receptors in vivo and for efficacy. These Fc-mediated activities, in combination with inhibition of both the EGFR and c-Met signaling pathways, highlight the multiple mechanisms by which JNJ-61186372 combats therapeutic resistance in EGFR mutant patients.

A Novel Bispecific Antibody Targeting EGFR and cMet Is Effective against EGFR Inhibitor-Resistant Lung Tumors.

Non-small cell lung cancers (NSCLC) with activating EGFR mutations become resistant to tyrosine kinase inhibitors (TKI), often through second-site mutations in EGFR (T790M) and/or activation of the cMet pathway. We engineered a bispecific EGFR-cMet antibody (JNJ-61186372) with multiple mechanisms of action to inhibit primary/secondary EGFR mutations and the cMet pathway. JNJ-61186372 blocked ligand-induced phosphorylation of EGFR and cMet and inhibited phospho-ERK and phospho-AKT more potently than the combination of single receptor-binding antibodies. In NSCLC tumor models driven by EGFR and/or cMet, JNJ-61186372 treatment resulted in tumor regression through inhibition of signaling/receptor downmodulation and Fc-driven effector interactions. Complete and durable regression of human lung xenograft tumors was observed with the combination of JNJ-61186372 and a third-generation EGFR TKI. Interestingly, treatment of cynomolgus monkeys with JNJ-61186372 resulted in no major toxicities, including absence of skin rash observed with other EGFR-directed agents. These results highlight the differentiated potential of JNJ-61186372 to inhibit the spectrum of mutations driving EGFR TKI resistance in NSCLC. Cancer Res; 76(13); 3942-53. ©2016 AACR.

Cross-arm binding efficiency of an EGFR x c-Met bispecific antibody.

Multispecific proteins, such as bispecific antibodies (BsAbs), that bind to two different ligands are becoming increasingly important therapeutic agents. Such BsAbs can exhibit markedly increased target binding and target residence time when both pharmacophores bind simultaneously to their targets. The cross-arm binding efficiency (χ) describes an increase in apparent affinity when a BsAb binds to the second target or receptor (R2) following its binding to the first target or receptor (R1) on the same cell. χ is an intrinsic characteristic of a BsAb mostly related to the binding epitopes on R1 and R2. χ can have significant impacts on the binding to R2 for BsAbs targeting two receptors on the same cell. JNJ-61186372, a BsAb that targets epidermal growth factor receptor (EGFR) and c-Met, was used as the model compound for establishing a method to characterize χ. The χ for JNJ-61186372 was successfully determined via fitting of in vitro cell binding data to a ligand binding model that incorporated χ. The model-derived χ value was used to predict the binding of JNJ-61186372 to individual EGFR and c-Met receptors on tumor cell lines, and the results agreed well with the observed IC50 for EGFR and c-Met phosphorylation inhibition by JNJ-61186372. Consistent with the model, JNJ-61186372 was shown to be more effective than the combination therapy of anti-EGFR and anti-c-Met monovalent antibodies at the same dose level in a mouse xenograft model. Our results showed that χ is an important characteristic of BsAbs, and should be considered for rationale design of BsAbs targeting two membrane bound targets on the same cell.

Impact of Cell-surface Antigen Expression on Target Engagement and Function of an Epidermal Growth Factor Receptor × c-MET Bispecific Antibody.

The efficacy of engaging multiple drug targets using bispecific antibodies (BsAbs) is affected by the relative cell-surface protein levels of the respective targets. In this work, the receptor density values were correlated to the in vitro activity of a BsAb (JNJ-61186372) targeting epidermal growth factor receptor (EGFR) and hepatocyte growth factor receptor (c-MET). Simultaneous binding of the BsAb to both receptors was confirmed in vitro. By using controlled Fab-arm exchange, a set of BsAbs targeting EGFR and c-MET was generated to establish an accurate receptor quantitation of a panel of lung and gastric cancer cell lines expressing heterogeneous levels of EGFR and c-MET. EGFR and c-MET receptor density levels were correlated to the respective gene expression levels as well as to the respective receptor phosphorylation inhibition values. We observed a bias in BsAb binding toward the more highly expressed of the two receptors, EGFR or c-MET, which resulted in the enhanced in vitro potency of JNJ-61186372 against the less highly expressed target. On the basis of these observations, we propose an avidity model of how JNJ-61186372 engages EGFR and c-MET with potentially broad implications for bispecific drug efficacy and design.

Discovery and characterization of a cell-permeable, small-molecule c-Abl kinase activator that binds to the myristoyl binding site.

c-Abl kinase activity is regulated by a unique mechanism involving the formation of an autoinhibited conformation in which the N-terminal myristoyl group binds intramolecularly to the myristoyl binding site on the kinase domain and induces the bending of the αI helix that creates a docking surface for the SH2 domain. Here, we report a small-molecule c-Abl activator, DPH, that displays potent enzymatic and cellular activity in stimulating c-Abl activation. Structural analyses indicate that DPH binds to the myristoyl binding site and prevents the formation of the bent conformation of the αI helix through steric hindrance, a mode of action distinct from the previously identified allosteric c-Abl inhibitor, GNF-2, that also binds to the myristoyl binding site. DPH represents the first cell-permeable, small-molecule tool compound for c-Abl activation.

Hepatic HIF-2 regulates erythropoietic responses to hypoxia in renal anemia.

The kidney is the main physiologic source of erythropoietin (EPO) in the adult and responds to decreases in tissue oxygenation with increased EPO production. Although studies in mice with liver-specific or global gene inactivation have shown that hypoxia-inducible factor 2 (Hif-2) plays a major role in the regulation of Epo during infancy and in the adult, respectively, the contribution of renal HIF-2 signaling to systemic EPO homeostasis and the role of extrarenal HIF-2 in erythropoiesis, in the absence of kidney EPO, have not been examined directly. Here, we used Cre-loxP recombination to ablate Hif-2α in the kidney, whereas Hif-2-mediated hypoxia responses in the liver and other Epo-producing tissues remained intact. We found that the hypoxic induction of renal Epo is completely Hif-2 dependent and that, in the absence of renal Hif-2, hepatic Hif-2 takes over as the main regulator of serum Epo levels. Furthermore, we provide evidence that hepatocyte-derived Hif-2 is involved in the regulation of iron metabolism genes, supporting a role for HIF-2 in the coordination of EPO synthesis with iron homeostasis.

An active form of Vav1 induces migration of mammary epithelial cells by stimulating secretion of an epidermal growth factor receptor ligand.

BACKGROUND: Vav proteins are guanine nucleotide exchange factors (GEF) for Rho family GTPases and are activated following engagement of membrane receptors. Overexpression of Vav proteins enhances lamellipodium and ruffle formation, migration, and cell spreading, and augments activation of many downstream signaling proteins like Rac, ERK and Akt. Vav proteins are composed of multiple structural domains that mediate their GEF function and binding interactions with many cellular proteins. In this report we examine the mechanisms responsible for stimulation of cell migration by an activated variant of Vav1 and identify the domains of Vav1 required for this activity. RESULTS: We found that expression of an active form of Vav1, Vav1Y3F, in MCF-10A mammary epithelial cells increases cell migration in the absence or presence of EGF. Vav1Y3F was also able to drive Rac1 activation and PAK and ERK phosphorylation in MCF-10A cells in the absence of EGF stimulation. Mutations in the Dbl homology, pleckstrin homology, or cysteine-rich domains of Vav1Y3F abolished Rac1 or ERK activation in the absence of EGF and blocked the migration-promoting activity of Vav1Y3F. In contrast, mutations in the SH2 and C-SH3 domains did not affect Rac activation by Vav1Y3F, but reduced the ability of Vav1Y3F to induce EGF-independent migration and constitutive ERK phosphorylation. EGF-independent migration of MCF-10A cells expressing Vav1Y3F was abolished by treatment of cells with an antibody that prevents ligand binding to the EGF receptor. In addition, conditioned media collected from Vav1Y3F expressing cells stimulated migration of parental MCF-10A cells. Lastly, treatment of cells with the EGF receptor inhibitory antibody blocked the Vav1Y3F-induced, EGF-independent stimulation of ERK phosphorylation, but had no effect on Rac1 activation or PAK phosphorylation. CONCLUSION: Our results indicate that increased migration of active Vav1 expressing cells is dependent on Vav1 GEF activity and secretion of an EGF receptor ligand. In addition, activation of ERK downstream of Vav1 is dependent on autocrine EGF receptor stimulation while active Vav1 can stimulate Rac1 and PAK activation independent of ligand binding to the EGF receptor. Thus, stimulation of migration by activated Vav1 involves both EGF receptor-dependent and independent activities induced through the Rho GEF domain of Vav1.

Epidermal growth factor receptor-dependent regulation of integrin-mediated signaling and cell cycle entry in epithelial cells.

Integrin-mediated adhesion of epithelial cells to extracellular matrix (ECM) proteins induces prolonged tyrosine phosphorylation and partial activation of epidermal growth factor receptor (EGFR) in an integrin-dependent and EGFR ligand-independent manner. Integrin-mediated activation of EGFR in epithelial cells is required for multiple signal transduction events previously shown to be induced by cell adhesion to matrix proteins, including tyrosine phosphorylation of Shc, Cbl, and phospholipase Cgamma, and activation of the Ras/Erk and phosphatidylinositol 3'-kinase/Akt signaling pathways. In contrast, activation of focal adhesion kinase, Src, and protein kinase C, adhesion to matrix proteins, cell spreading, migration, and actin cytoskeletal rearrangements are induced independently of EGFR kinase activity. The ability of integrins to induce the activation of EGFR and its subsequent regulation of Erk and Akt activation permitted adhesion-dependent induction of cyclin D1 and p21, Rb phosphorylation, and activation of cdk4 in epithelial cells in the absence of exogenous growth factors. Adhesion of epithelial cells to the ECM failed to efficiently induce degradation of p27, to induce cdk2 activity, or to induce Myc and cyclin A synthesis; subsequently, cells did not progress into S phase. Treatment of ECM-adherent cells with EGF, or overexpression of EGFR or Myc, resulted in restoration of late-G(1) cell cycle events and progression into S phase. These results indicate that partial activation of EGFR by integrin receptors plays an important role in mediating events triggered by epithelial cell attachment to ECM; EGFR is necessary for activation of multiple integrin-induced signaling enzymes and sufficient for early events in G(1) cell cycle progression. Furthermore, these findings suggest that EGFR or Myc overexpression may provoke ligand-independent proliferation in matrix-attached cells in vivo and could contribute to carcinoma development.

Vav GEFs are required for beta2 integrin-dependent functions of neutrophils.

Integrin regulation of neutrophils is essential for appropriate adhesion and transmigration into tissues. Vav proteins are Rho family guanine nucleotide exchange factors that become tyrosine phosphorylated in response to adhesion. Using Vav1/Vav3-deficient neutrophils (Vav1/3ko), we show that Vav proteins are required for multiple beta2 integrin-dependent functions, including sustained adhesion, spreading, and complement-mediated phagocytosis. These defects are not attributable to a lack of initial beta2 activation as Vav1/3ko neutrophils undergo chemoattractant-induced arrest on intercellular adhesion molecule-1 under flow. Accordingly, in vivo, Vav1/3ko leukocytes arrest on venular endothelium yet are unable to sustain adherence. Thus, Vav proteins are specifically required for stable adhesion. beta2-induced activation of Cdc42, Rac1, and RhoA is defective in Vav1/3ko neutrophils, and phosphorylation of Pyk2, paxillin, and Akt is also significantly reduced. In contrast, Vav proteins are largely dispensable for G protein-coupled receptor-induced signaling events and chemotaxis. Thus, Vav proteins play an essential role coupling beta2 to Rho GTPases and regulating multiple integrin-induced events important in leukocyte adhesion and phagocytosis.

Vav1/2/3-null mice define an essential role for Vav family proteins in lymphocyte development and activation but a differential requirement in MAPK signaling in T and B cells.

The Vav family of Rho guanine nucleotide exchange factors is thought to orchestrate signaling events downstream of lymphocyte antigen receptors. Elucidation of Vav function has been obscured thus far by the expression of three highly related family members. We generated mice lacking all Vav family proteins and show that Vav-null mice produce no functional T or B cells and completely fail to mount both T-dependent and T-independent humoral responses. Whereas T cell development is blocked at an early stage in the thymus, immature B lineage cells accumulate in the periphery but arrest at a late "transitional" stage. Mechanistically, we show that the Vav family is crucial for both TCR and B cell receptor (BCR)-induced Ca2+ signaling and, surprisingly, is only required for mitogen-activated protein kinase (MAPK) activation in developing and mature T cells but not in B cells. Thus, the abundance of immature B cells generated in Vav-null mice may be due to intact Ras/MAPK signaling in this lineage. Although the expression of Vav1 alone is sufficient for normal lymphocyte development, our data also reveal lineage-specific roles for Vav2 and Vav3, with the first demonstration that Vav3 plays a critical compensatory function in T cells. Together, we define an essential role for the entire Vav protein family in lymphocyte development and activation and establish the limits of functional redundancy both within this family and between Vav and other Rho-guanine nucleotide exchange factors.

Coordinate interactions of Csk, Src, and Syk kinases with [alpha]IIb[beta]3 initiate integrin signaling to the cytoskeleton.

Integrins regulate cell adhesion and motility through tyrosine kinases, but initiation of this process is poorly understood. We find here that Src associates constitutively with integrin alphaIIbbeta3 in platelets. Platelet adhesion to fibrinogen caused a rapid increase in alphaIIbbeta3-associated Src activity, and active Src localized to filopodia and cell edges. Csk, which negatively regulates Src by phosphorylating Tyr-529, was also constitutively associated with alphaIIbbeta3. However, fibrinogen binding caused Csk to dissociate from alphaIIbbeta3, concomitant with dephosphorylation of Src Tyr-529 and phosphorylation of Src activation loop Tyr-418. In contrast to the behavior of Src and Csk, Syk was associated with alphaIIbbeta3 only after fibrinogen binding. Platelets multiply deficient in Src, Hck, Fgr, and Lyn, or normal platelets treated with Src kinase inhibitors failed to spread on fibrinogen. Inhibition of Src kinases blocked Syk activation and inhibited phosphorylation of Syk substrates (Vav1, Vav3, SLP-76) implicated in cytoskeletal regulation. Syk-deficient platelets exhibited Src activation upon adhesion to fibrinogen, but no spreading or phosphorylation of Vav1, Vav3, and SLP-76. These studies establish that platelet spreading on fibrinogen requires sequential activation of Src and Syk in proximity to alphaIIbbeta3, thus providing a paradigm for initiation of integrin signaling to the actin cytoskeleton.