CD33 and leukemia: Compared with a BiFab against CD33 and CD3 generated using the same methodology, the CLL1-CD3 antibody-mediated stronger in vitro cytotoxicity and superior in vivo anti-tumor activity in immunodeficient mice with established leukemia xenografts receiving expanded T cells.68 Another laboratory also successfully demonstrated the in vitro functionality of a CLL1-CD3 BiTE in the presence of T cells against AML cells.69