Exploring CD19-targeted Immunotherapy Strategies for Human B-cell Lymphoma

B-cell lymphomas (BCLs) encompass approximately 40 subtypes arising from the malignant transformation of mature B-cells. The management of BCLs varies according to the specific type and stage of lymphoma. A plethora of therapeutic options are available, encompassing chemotherapy, immunotherapy, radiation therapy, targeted therapy, and stem cell transplantation. Among these approaches, targeted therapy has demonstrated considerable promise in terms of its potential to enhance safety and efficacy in treatment regimens. The field of targeted therapies encompasses a range of treatments that are designed to target specific molecules and pathways involved in various diseases. These therapies include monoclonal antibodies, nanobodies, CAR-T cell therapies, and bispecific T-cell engager (BiTE) molecules. These therapeutic agents operate through various mechanisms, targeting a variety of molecules and receptors associated with different diseases, such as CD79b, CD20, CD30, CD52, and CD19. CD19 is an immunoglobulin superfamily transmembrane glycoprotein of type I, which is necessary for setting intrinsic B-cell signaling thresholds by tempering both receptor-dependent and receptor-independent signaling. Conventional therapeutic interventions and other targets have demonstrated limitations, suggesting that CD19 is a viable target for lymphoma treatment. There are several FDA-approved anti-CD19 CAR-T cells, including Axicabtagene Ciloleucel, Tisagenlecleucel, and Lisocabtagene Maraleucel, as well as anti-CD19 monoclonal antibodies (mABs), such as loncastuximab tesirine and tafasitamab. These agents have demonstrated efficacy in numerous clinical trials. Blinatumomab, the inaugural FDA-approved antibody to be produced using BiTE technology, has demonstrated notable benefits in clinical trials investigating its use in the treatment of B-cell acute lymphoblastic leukemia (B-ALL). Single-domain antibodies (sdAb) or nanobodies represent the nanoscale VHH fragments of heavy chain-only antibodies (HcAbs). These have been utilized in conjunction with CAR T-cells, yielding promising outcomes. In this review, we sought to explore the potential of CD19 as a promising therapeutic target for lymphoma. Furthermore, we engaged in a discourse on the various treatment options concerning CD19 targeting, accompanied by an exposition of the pertinent clinical studies. In this regard, the efficacy, safety, and limitations of each option were thoroughly delineated.