Fig. 1

Schematic representation of sdCAR-engineered T cells. a Engineered T cells endowed with the sdCAR structure can eliminate MSLN⁺ K562 tumor cells in the presence of FHBM. Engineered T cells can release perforin and granzyme when they contact cognate target cells expressing both integrin αvβ3 and MSLN in the presence of a switch molecule (FHBM). Perforin can form a perforated tubular channel on the target cell membrane, resulting in the destruction of target cells. In addition, released granzyme rapidly enters the cytoplasm through perforin-dependent pores on the target cell membrane and then triggers caspase reactions that lead to target cell DNA degradation and tumor cell apoptosis. b The sdCAR design distributes key components (CD3ζ and 4-1BB elements) into two physically separate structures that can be conditionally controlled by a switch molecule and cognate tumor cells, respectively. The novel design involves an AND logic gate including the “cognate tumor cell + switch molecule” combinatorial inputs for T cell activation. Therefore, the sdCAR-engineered T cells should activate only when simultaneously exposed to the switch molecule (FHBM) and cognate tumor cells. c Structure of the plasmid used to transfect T cells. After transfection with this plasmid, effector cells expressed the novel sdCAR structure consisting of anti-MSLN scFv, anti-FITC scFv, two signal domains of 4-1BB and CD3ζ, and the fluorescence reporter protein BFP