Targeted therapies in hematological malignancies using therapeutic monoclonal antibodies against Eph family receptors  Sara Charmsaz, Andrew M. Scott, Andrew W. Boyd  Experimental Hematology  Volume 54, Pages 31-39 (October 2017) DOI: 10.1016/j.exphem.2017.07.003 Copyright © 2017 ISEH – Society for Hematology and Stem Cells Terms and Conditions

Figure 1 Mechanism of action of mAb therapy. (A) Naked mAb can function through various mechanisms, including antibody dependent cellular cytotoxicity (ADCC) using immune effector cells such as natural killer (NK) cells. Complement-mediated cytotoxicity (CMC) functions through the membrane attack complex and by inhibition of the receptor dimerization, inducing an apoptotic signal or through effecting target cells by blocking the binding of ligand. Immune checkpoint inhibitors, including PD-1, function by blocking the T-cell-inhibitory receptors and CTLA-4, which function through activation of T-cell function. (B) Conjugated mAb includes payload antibody for delivery of specific drugs or chemotherapy agents directly to the tumor cells, radioimmunoconjugates to deliver radioisotopes to the cancer cells, immunotoxins to deliver highly toxic drugs to the target cells, and siRNA particles to downregulate a target gene. (C) CAR T-cell therapy uses a genetically engineered T cell to target a specific antigen on tumor cells. (D) Bispecific mAbs consist of two arms, with one arm recognizing cancer cells and the other activating antigens on immune effector cells including CD3. Experimental Hematology 2017 54, 31-39DOI: (10.1016/j.exphem.2017.07.003) Copyright © 2017 ISEH – Society for Hematology and Stem Cells Terms and Conditions

Figure 2 Eph receptors and ephrin ligands. Shown is a schematic representation of the Eph receptors (EphA and EphB) and ephrin ligands and a summary of Eph/ephrin interactions showing broad ligand-binding preferences. As illustrated, most EphA receptors bind to ephrinA ligand preferentially and most EphB receptors bind to ephrinB ligands preferentially, with some exceptions (including EphA4 and EphB2) showing cross-class binding. Experimental Hematology 2017 54, 31-39DOI: (10.1016/j.exphem.2017.07.003) Copyright © 2017 ISEH – Society for Hematology and Stem Cells Terms and Conditions

Figure 3 mAbs directed against Eph proteins in preclinical studies and in clinical trials. (A) mAb against EphA2 3F2-3M138 functions through ADCC and promotes EphA2 internalization and degradation. The auristatin-conjugated EphA2 mAb (MEDI-547) acts via toxin-mediated tumor cell killing, and the new CAR T-cell EphA2 immunotherapy currently in clinical trial is an EphA2-specific T-cell immunotherapy used for the treatment of EphA2-positive glioblastoma. Preclinical EphA2 mAb studies show therapeutic response from using IF-7 mAb against EphA2 and radiolabeled conjugated form of IF7-lutetium177. (B) mAb against EphA3, including IIIA4, activates EphA3 and the humanized form of the mAb (KB004) causes ADCC and apoptosis. It is currently in clinical trial. Other conjugated forms of this mAb are lutetium177 or bismuth215 conjugates, which were proven effective in the preclinical setting. (C) The soluble EphA7 exodomain–rituximab fusion protein blocks oncogenic signals and works as a negative inhibitor of Eph signaling. (D) EphB4 mAb inhibits tumor angiogenesis, and the sEphB4–human serum albumin (HSA) fusion protein works by blocking the angiogenic EphB4–ephrinB2 signaling. It is currently in clinical trial. Experimental Hematology 2017 54, 31-39DOI: (10.1016/j.exphem.2017.07.003) Copyright © 2017 ISEH – Society for Hematology and Stem Cells Terms and Conditions