High-throughput engineering of bispecific antibodies to enhance macrophage-mediated cytotoxicity of B-cell lymphoma.

Macrophages are critical effectors of antibody therapies for lymphoma, but the best targets to engage their function remain unknown. Here, we develop a 'tactical surfaceome profiling' strategy to define a comprehensive repertoire of surface antigens on B-cell lymphoma that can be targeted with antibodies to provoke macrophage attack. Across both mouse and human systems, we identify multiple unappreciated targets of opsonization as well as putative immune checkpoints. We incorporate this information into a high-throughput engineering strategy, creating 156 bispecific antibodies and identifying dozens that stimulate macrophage-mediated cytotoxicity. A heterodimeric scFv-Fc format enables our approach; it is superior to conventional bispecific antibody design and offers enhanced activity while reducing developmental complexity. Among the therapeutics we create, a bispecific comprising a SIRPα decoy domain and a CD38-targeting arm (WTa2d1xCD38) exhibits maximal efficacy with reduced risk of toxicity. This bispecific stimulates robust anti-tumor responses in xenograft models of aggressive B-cell lymphoma and shows benefits over anti-CD20 antibody rituximab. Our approach can be applied to other cancers to leverage anti-tumor responses by macrophages or other immune cells.