A novel humanized anti‐tumor necrosis factor‐related apoptosis‐inducing ligand‐R2 monoclonal antibody induces apoptotic and autophagic cell death

It is well known that the tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL/TNFSF10) is specifically expressed in various tumor cells, but less or no expression in most normal tissues and cells. While TRAIL engages with its native death receptors, TRAIL receptor 1 (TRAIL‐R1) or 2 (TRAIL‐R2), usually elicits the tumor cell death by apoptosis. In this study, we report that a novel humanized monoclonal antibody against TRAIL‐R2 (named as zaptuzumab) well remain the biological activity of the parental mouse antibody AD5‐10 inducing cell death in various cancer cells, but little effect on normal cells. Zaptuzumab also markedly inhibited the tumor growth in the mouse xenograft of NCI‐H460 without toxicity to the liver and kidney, and the efficacy of tumor suppression was increased significantly while it combined with cis‐dichlorodiamineplatinum. Especially, 131I‐labeled zaptuzumab injected into mouse tail vein specifically targeted to the xenograft of the lung cancer cells. Confocal analysis showed that zaptuzumab bound with TRAIL‐R2 on cell surface could be quickly internalized and transferred into the lysosome. Furthermore, zaptuzumab possessed a high level of antibody‐dependent cytotoxicity as well as complement‐dependent cytotoxicity. Study on the mechanisms of cell death induced by zaptuzumab showed that it efficiently induced both caspase‐dependent apoptosis and autophagic cell death. These data suggest that the humanized anti‐TRAIL‐R2 monoclonal antibody or the second generation of the antibody may have an important clinical usage for cancer immunotherapy. © 2017 IUBMB Life, 69(9):735–744, 2017