Preclinical development of three novel CARs targeting CD79b for the treatment of non-Hodgkin's lymphoma and characterization of the loss of the target antigen.

Background: Infusion of T cells modified with a chimeric antigen receptor (CAR) targeting CD19 has achieved exceptional responses in patients with non-Hodgkin's lymphoma (NHL), which led to the approval of CAR targeting CD19 (CART19) (Axi-cel and Liso-cel) as second line of treatment for adult patients with relapsed/refractory NHL. Unfortunately, 60% of patients still relapse after CART19 due to either a loss of expression of the target antigen (CD19) in the tumor cell, observed in 27% of relapsed patients, a limited CAR-T persistence, and additional mechanisms, including the suppression of the tumor microenvironment. Clinic strategies to prevent target antigen loss include sequential treatment with CARs directed at CD20 or CD22, which have caused loss of the second antigen, suggesting targeting other antigens less prone to disappear.