CD19 is a member of the immunoglobulin superfamily of proteins expressed on the surface of B cells at most stages of their development, where it functions as a critical component of the B cell receptor-signaling complex (Depoil D et al 2008). CD19 is an ideal target for CAR-targeted therapies because it is expressed on most malignant B cells (including CLL, B-ALL, and many NHL), is not expressed on hematopoietic stem cells, and elimination of all CD19+ B cells in the body is a manageable on-target treatment effect (Scheuermann RH et al.1995).
A potential disadvantage of CD19 as a target is that its surface expression is not required for maintenance of the tumorigenic phenotype, and escape variants have been noted (Maude SL et al. 2014; Evans AG et al. 2015). Although not the first to be studied, CAR T-cell therapies directed against CD19 are the most mature to date (Kochenderfer JN et al. 2009). Second-generation CAR with are selected CD3ζ- and 4-1BB-stimulating domains, which is produced with a lentiviral transduction system .
Indications for anti-CD19 CAR T-cell therapy include B-cell non-Hodgkin lymphoma (Abramson JS 2020).
It is known that autoreactive B cells play a key role in the development of autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis. B-cell-depleting monoclonal antibodies such as rituximab have low therapeutic efficacy in autoimmune diseases (persistence of autoreactive B cells in lymphoid organs and inflamed tissues?). CD19 CAR-T cells have been introduced into autoimmune disease therapy in recent years. CD19 CAR-T cells resulted in rapid and sustained depletion of circulating B cells and complete clinical and serological remission of refractory systemic lupus erythematosus and dermatomyositis (Carney EF 2022; Kambayana G et al. 2023; Schett G et al. 2023).