An antibody-toxin conjugate targeting CD47 linked to the bacterial toxin listeriolysin O for cancer immunotherapy

Antigen-presenting cells phagocytose tumor cells and subsequently cross-present tumor-derived antigens. However, these processes are impeded by phagocytosis checkpoints and inefficient cytosolic transport of antigenic peptides from phagolysosomes. Here, using a microbial-inspired strategy, we engineered an antibody-toxin conjugate (ATC) that targets the 'don't eat me' signal CD47 linked to the bacterial toxin listeriolysin O from the intracellular bacterium Listeria monocytogenes via a cleavable linker (CD47-LLO). CD47-LLO promotes cancer cell phagocytosis by macrophages followed by LLO release and activation to form pores on phagolysosomal membranes that enhance antigen cross-presentation of tumor-derived peptides and activate cytosolic immune sensors. CD47-LLO treatment in vivo significantly inhibited the growth of both localized and metastatic breast and melanoma tumors and improved animal survival as a monotherapy or in combination with checkpoint blockade. Together, these results demonstrate that designing ATCs to promote immune recognition of tumor cells represents a promising therapeutic strategy for treating multiple cancers.