A bispecific chimeric antigen receptor (CAR) T-cell therapy targeting CD19 and CD22 induced remission in adult patients with relapsed/refractory B-cell acute lymphocytic leukemia (ALL), according to a study published in the Journal of Hematology & Oncology.
In this phase I study, patients received CAR T-cell therapy doses ranging from 1.7×106 to 3×106 CAR T-cells/kg of body weight. This bispecific CAR T-cell therapy triggered robust cytolytic activity against target cells, according to the author. All six patients included in the study achieved minimal residual disease-negative complete remission.
According to the results, autologous CD19/CD22 CAR T-cells proliferated in vivo and were detected in the blood, bone marrow, and cerebrospinal fluid. While no patients reported neurotoxicity, one patient relapsed with blast cells that no longer expressed CD19 and exhibited diminished CD22 site density approximately five months post-treatment.
“Autologous CD19/CD22 CAR T-cell therapy is feasible and safe and mediates potent antileukemic activity in patients with relapsed/refractory B-ALL,” the authors concluded. “The emergence of target antigen loss and expression downregulation highlights the critical need to anticipate antigen escape.”