Engineering of a sweeping antibody against IL-16 for the treatment of autoimmune diseases and cancer 2431

Abstract Description Interleukin-16 (IL-16) is a pleiotropic cytokine secreted by lymphocytes upon stimulation. IL-16 is implicated in the pathogenesis of autoimmune diseases and cancer and preclinical models suggest that blocking IL-16 signaling has therapeutic potential. In this project, we aimed to target IL-16 using engineered antibodies. Sweeping antibodies (swAbs) contain two modifications, pH-dependent antigen binding and enhanced neonatal Fc receptor (FcRn) binding, resulting in 50-1,000-fold increased clearance of target antigen compared to wildtype (WT) antibodies. Here, we attempted to convert two WT anti-IL-16 antibodies into swAbs: 1) a novel, fully-human, high affinity antibody developed in our lab (3B6) and 2) a previously established mouse antibody (14.1). We used histidine-scanning mutagenesis of the variable regions to introduce pH-dependent binding, which was quantified by custom ELISAs/TRFIAs and bio-layer interferometry. Mutagenesis of 14.1 produced three highly pH-dependent binders and, in vitro assays using these IL-16 swAbs showed enhanced cellular uptake and degradation of IL-16 compared to WT antibodies. We are currently determining biodistribution and therapeutic activity of these antibodies in vivo. In contrast, successive rounds of engineering pH dependency in 3B6 were unsuccessful. We are currently determining the epitope of 3B6 to better understand its resistance to swAb engineering. This project informs swAb engineering and the therapeutic targeting of IL-16. Funding Sources Supported by NIAID T32AI095190; Maryland Department of Health’s Cigarette Restitution Fund Program (CH-649-CRF). Topic Categories Therapeutic Approaches to Autoimmunity (THER)