Development of a novel CD19/BCMA dual CAR-T for autoimmune diseases

Abstract CD19 and BCMA CAR-T therapies have recently gained widespread application in the field of autoimmune diseases, demonstrating remarkable clinical efficacy. Compared to single-target (CD19 or BCMA) CAR-T therapies, dual-targeting CD19/BCMA CAR-T appears to more effectively eliminate pathogenic immune cells, enabling patients to achieve deeper and more sustained remission. In this study, we developed a novel humanized anti-CD19 monoclonal antibody, which exhibits comparable cytotoxicity against Raji tumor cells to FMC63 but binds to a distinct epitope on CD19, which holds therapeutic potential for patients who relapse after FMC63-based treatments. Meanwhile, we engineered a new humanized anti-BCMA monoclonal antibody, and this BCMA CAR-T is capable of effectively clearing BCMA-positive tumor cells. Using these newly developed antibodies, we constructed diverse CD19/BCMA dual CAR structures, including tandem and compound CARs with varying co-stimulatory domains. Our results demonstrated that compound CAR-T cells with different co-stimulatory domains exhibited enhanced CD19/BCMA-CAR expression, and superior cytotoxicity by effectively eliminating CD19-positive or BCMA-positive tumor cells both in vitro and in vivo. To adapt CD19/BCMA dual CAR-T for autoimmune disease treatment, The safety concerns associated with conventional lenti-viral transduction platforms, which may lead to uncontrolled CAR-T expansion and adverse effects such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), need to be addressed. To mitigate these risks, we developed an LNP-mRNA-based platform for transient CAR-T engineering, by which the CAR expression on T cells could reach ~60%. This approach allows for manageable and repeated dosing to reset the immune system, meanwhile significantly improves the safety. In conclusion, we successfully developed a novel CD19/BCMA dual CAR-T construct. Concurrently, we established an innovative ex vivo LNP-mRNA platform for T cell engineering. In future, we will initiate clinical trials to evaluate this therapeutic product for autoimmune diseases.