Transient CAR T cells with specificity to oncofetal glycosaminoglycans in solid tumors

Glycosaminoglycans are often deprioritized as targets for synthetic immunotherapy due to the complexity of glyco-epitopes and limited options for obtaining specific subtype binding. Solid tumors express proteoglycans that are modified with oncofetal chondroitin sulfate (CS), a modification normally restricted to the placenta. Here, we report the design and functionality of transient chimeric antigen receptor (CAR) T cells with selectivity to oncofetal CS. Following expression in T cells, the CAR could be "armed" with recombinant VAR2CSA lectins (rVAR2) to target tumor cells expressing oncofetal CS. While unarmed CAR T cells remained inactive in the presence of target cells, VAR2-armed CAR T cells displayed robust activation and the ability to eliminate diverse tumor cell types in vitro. Cytotoxicity of the CAR T cells was proportional to the concentration of rVAR2 available to the CAR, offering a potential molecular handle to finetune CAR T cell activity. In vivo, armed CAR T cells rapidly targeted bladder tumors and increased the survival of tumor-bearing mice. Thus, our work indicates that cancer-restricted glycosaminoglycans may be exploited as potential targets for CAR T cell therapy. Transient VAR2-[SpyT][SpyC]-CAR T cells targeting oncofetal chondroitin sulfate (CS) show high specificity and activity against solid tumor cells, adding glycosaminoglycans to the list of potential actionable targets for CAR T cell therapy in solid tumors.Transient CAR T cells were developed to target oncofetal CS, unique to cancer cells.VAR2-[SpyT]-armed CAR T cells demonstrated robust activation, cytokine production, and cytotoxicity in vitro.The targeting mechanism offers high specificity and potential broad applicability across various solid tumors.VAR2-[SpyT][SpyC]-CAR T cells inhibited tumor growth and increased survival in vivo.The VAR2-[SpyT][SpyC]-CAR T cell system provides proof-of-concept for oncofetal CS as a potential target for CAR T cell approaches. Transient VAR2-[SpyT][SpyC]-CAR T cells targeting oncofetal chondroitin sulfate (CS) show high specificity and activity against solid tumor cells, adding glycosaminoglycans to the list of potential actionable targets for CAR T cell therapy in solid tumors.