Co-expression of an adapter CAR retains efficacy of CAR T cells after single and dual antigen loss in lymphoma

CAR-T cell therapy is effective in many patients suffering from B cell malignancies, yet antigen escape is a major resistance mechanism by which efficacy can be diminished or lost. To counter this, we enhance anti-lymphoma CAR-T cells by generating conventional and adapter dual (ConvAD) CAR-T cells, which co-express a conventional antigen-specific CAR and the P329G adapter CAR that leverages Fc-mutated antibodies for redirection. ConvAD CAR-T cells display robust functionality against the primary lymphoma antigen of the conventional CAR while providing flexible redirection to additional targets via target-specific adapters in the event of antigen escape. We demonstrate the bimodal activity of ConvAD CAR-T cells acting through direct engagement of the conventional CAR as well as through binding of adapters, resulting in enhanced multispecific anti-lymphoma targeting. In vitro and in vivo, ConvAD CAR-T cells targeting combinations of ROR1, CD19, and CD20 prevent lymphoma outgrowth across models of stable antigen expression as well as single- or dual-antigen loss, and benchmark superior to both single-antigen specific and bispecific CAR-T cells. The ConvAD CAR platform thus addresses a medical need by offering an effective strategy for multi-antigen targeting, counteracting antigen escape.