Anti-CD19 chimeric antigen receptor (CAR)-engineered T and NK cell therapies have revolutionized the treatment of B cell malignancies, but challenges including CD19 antigen loss greatly hinder their full therapeutic potential. Here we demonstrated that co-treatment with anti-CD19 monoclonal antibody enhances antitumor activity of anti-CD19 CAR-T and -NK cells. Even though the treated antibody interferes with CD19 antigen binding of CAR, it significantly induces rapid detachment of anti-CD19 …