i-shaped antibody engineering enables conformational tuning of biotherapeutic receptor agonists
The ability to leverage antibodies to agonize disease relevant biological pathways has the potential to unlock new drug targets for clinical investigation. While antibodies have been successful as antagonists, immune mediators, and targeting agents, they are not readily effective at recapitulating the biological activity of natural ligands. Among the important determinants of antibody agonist activity is the geometry of target receptor engagement. Herein, we describe a novel engineering approach inspired by a naturally occurring Fab-Fab homotypic interaction that constrains IgG in a unique i-shaped conformation. i-shaped antibody (iAb) engineering enables potent intrinsic agonism of five tumor necrosis factor receptor superfamily (TNFRSF) targets. When applied to bispecific antibodies against the heterodimeric IL-2 receptor pair, constrained bispecific IgG formats recapitulate IL-2 agonist activity. Thus, iAb engineering represents a new tool to tune agonist antibody function and this work provides a framework for the development of intrinsic antibody agonists with the potential for generalization across broad receptor classes. Overall design: We aim to assess the effect of antibody based mimetics of IL2 on gene expression in primary CD8 T cells as compared to recombinant IL2. We have found that constrained antibody formats are capable of inducing signaling and proliferation comparable to IL2 in multiple assays and would like to extend this study to transcriptomic analysis. Each condition was tested in triplicate.