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• Agonist antibodies have emerged as promising therapeutics for receptor agonism. • Discovery methods have been adapted based on the endogenous signaling mechanisms. • High-throughput screening for agonist function enables improved discovery efficiency. • Computational methods are being used to design and optimize agonist antibodies. • Molecular engineering has remedied the limited activity and safety of some IgGs. Agonist antibodies that activate cellular signaling have emerged as promising therapeutics for treating myriad pathologies. Unfortunately, the discovery of rare antibodies with the desired agonist functions is a major bottleneck during drug development. Nevertheless, there has been important recent progress in discovering and optimizing agonist antibodies against a variety of therapeutic targets that are activated by diverse signaling mechanisms. Herein, we review emerging high-throughput experimental and computational methods for agonist antibody discovery as well as rational molecular engineering methods for optimizing their agonist activity. [ABSTRACT FROM AUTHOR]

Agonist antibodies are being pursued for therapeutic applications ranging from neurodegenerative diseases to cancer. For the tumor necrosis factor (TNF) receptor superfamily, higher-order clustering of three or more receptors is key to their activation, which can be achieved using antibodies that recognize two unique epitopes. However, the generation of biepitopic (i.e., biparatopic) antibodies typically requires animal immunization and is laborious and unpredictable. Here, we report a simple method for identifying biepitopic antibodies that potently activate TNF receptors without the need for additional animal immunization. Our approach uses existing, receptor-specific IgGs, which lack intrinsic agonist activity, to block their corresponding epitopes, then selects single-chain antibodies that bind accessible epitopes. The selected antibodies are fused to the light chains of IgGs to generate human tetravalent antibodies. We highlight the broad utility of this approach by converting several clinical-stage antibodies against OX40 and CD137 (4-1BB) into biepitopic antibodies with potent agonist activity. [Display omitted] • Simple method for identifying biepitopic antibodies that activate TNF receptors • Competition-based platform allowing high-throughput screening of yeast libraries • Biepitopic antibodies potently activate primary human T cells The generation of biepitopic antibodies typically requires animal immunization and is a laborious and unpredictable process. Jhajj et al. report a simple method for selecting antibodies with unique epitope pairs that can be combined into biepitopic agonist antibodies with potent activity against multiple clinically relevant TNF receptors. [ABSTRACT FROM AUTHOR]