Development of small molecule modulators of CTLA-4 as a novel strategy for safe and effective immunotherapies 9305

Abstract Description Antibody-based immune checkpoint inhibitors have revolutionized cancer therapy but often cause severe adverse events and resistance. We sought to develop small-molecule CTLA-4 modulators as safer, equally effective alternatives for both cancer and autoimmune applications, avoiding unwanted protein degradation and immune-related toxicities. To this end, we expressed and purified the extracellular domains of CTLA-4, CD86, and CD80 in human cells, confirming stability and function via dendritic cell binding assays and thermal shift analysis. By harnessing an expansive DNA-encoded library (DEL) of over four billion unique compounds, we uncovered highly specific candidate small molecules targeting CTLA-4, CD80, and their complex. Molecules that specifically bind CTLA-4 could enhance T-cell activation for cancer immunotherapy, whereas those that target the CTLA-4/CD80 complex could heighten immunosuppression and thus prove beneficial in autoimmune conditions. Following a multi-step synthetic effort—encompassing repeated purification and thorough structural validation to confirm each compound’s purity and identity—rigorous biophysical assays verified the binding interactions of these molecules, laying a solid foundation for next-generation immunomodulation strategies. These results highlight the importance of small-molecule specificity in designing targeted agents, setting the stage for further optimization and therapeutic exploration. Topic Categories Translational and Interventional Immunology (TI)