The anti-tumor activity of T cells, initiated via the T-cell receptor (TCR), can be enhanced through costimulatory engagement of the CD28 co-receptor. This costimulation can be leveraged therapeutically using CD28-binding antibodies to improve the efficacy of T-cell activating strategies, such as CD3 T-cell engagers (TCEs), in the tumor microenvironment. 

In this case study, we present a panel of CD28-binding HCAbs and IgG antibodies. These antibodies bind a broad range of epitopes, leading to diverse functional activity that is clearly differentiated from benchmarks with known toxicity issues. Combining these molecules with other T-cell activating strategies represents an opportunity to fine-tune novel costimulatory TCEs for diverse tumor targets.