CD22 and neoplasm: Other reported mechanisms of relapse include downregulation of CD22 antigen in loss of response to CD22 CAR-T cells, in a patient who previously lost CD19 expression as well (79), tumor cell–mediated CAR-T trogocytosis (the transfer of the target antigen to the effector T cell) (80) and CAR neutralizing antibody formation (24, 25, 64).