[Comment] Driving two chimeric antigen receptors (CARs) in a row to reduce antigen escape in B-cell acute lymphocytic leukaemia

Chimeric antigen receptor (CAR)-modified T cells targeting CD19 have led to unprecedented complete remission rates of 70–98% in relapsed and refractory B-cell acute lymphocytic leukaemia. However, up to 50% of patients experience a disease relapse.1 Given that antigen escape is a major contributor to relapse or lack of response after single-antigen targeted CARs,2 it has been hypothesised that multi-antigen targeting could overcome escape, thereby improving remission durability. Clinical experience with CARs targeting both CD19 and CD22 is amassing rapidly.