CLEC12A and leukemia: A luciferase-based cytotoxicity assay using U937 histiocytic lymphoma cells demonstrated that CLL1CART containing a CD8α H + TM and 4-1BB co-stim evoked more effective anti-leukemia activity than the other three constructs compared to empty CAR (same CAR backbone as anti-CLL-1 CAR but without an antigen recognition domain) (Fig. 4B).