IMPACTing autoimmunity through dual targeting of antigen presenting cells and T cells via inhibitory receptor agonism

Abstract

Abstract Autoimmune diseases are triggered by a critical break in peripheral tolerance, thereby allowing the immune system to target and destroy host tissues. Tolerance mechanisms, such as inhibitory receptor (IRs) on T cells, can greatly influence autoimmune disease progression and outcomes, representing an opportunity for therapeutic intervention. Indeed, evidence in both animal models and patients suggests that IRs play a major role in limiting autoimmunity. Immunotherapies targeting IRs have revolutionized the treatment of many cancers and provided evidence that IR modulating therapeutics can significantly impact patient outcomes. However importantly, analogous IR-targeted autoimmune therapeutics have just begun to be tested. Despite interest, IR agonist antibodies have proven difficult to generate. Optimal agonist antibodies require IR superclustering, which is not efficiently induced by Fc-null antibodies. Successful agonists will likely rely on simultaneous Fc (constant region) tethering on antigen presenting cells (APC), thereby allowing efficient IR superclustering and downstream signaling. Current agonistic antibodies targeting IRs contain an IgG1 wild-type Fc, which by binding both activating and inhibitory Fc receptors can trigger unwanted production of inflammatory cytokines by APCs. Here we show that antibodies binding selectively FcγRIIb, support superior agonism compared to IgG1 wild-type antibodies and mitigate potential liability of current IR agonists under clinical investigation. Indeed, dual targeting of the APC and T cells shows promising pre-clinical results and will be used to create novel IR agonists.