Reviving low-affinity glycan-targeting CAR with combinatorial design

CD19CAR T cells demonstrate remarkable therapeutic efficacy in the treatment of B cell malignancies. A global limitation of conventional CD19CAR therapy is its mono-specificity. Thus, defining complementary targets to CD19 is critical to avoid target-dependent limitations. Alternatives to protein antigens include secondary modifications, such as glycosylation. One example of aberrant glycosylation in lymphoma is the increase in N-glycans capped with α2,6-linked sialic acid, named CD75s. Here, we generate a CAR that recognizes CD75s based on an IgM monoclonal antibody called HH2. HH2CAR shows cytotoxic activity against B cell lymphoma cell lines, although it induces little to no cytokine release. However, while HH2CAR alone cannot control tumor progression in vivo, its combination with CD19CAR results in a functional molecule. Beyond overcoming the limited efficiency of HH2CAR T cells, this combination also prevents potential off-tumor/on-target toxicity associated with CD19 single targeting. Thus, inefficient mono-specific CAR molecules can be effectively leveraged in combinatorial formats.