Background/Purpose: B cells are pivotal in autoimmune disease pathogenesis as they produce autoantibodies and undergo aberrant maturation processes, and B-cell dysregulation and the production of autoreactive long-lived plasma cells (LLPCs) have been identified as a possible mechanism in chronic disease. Recently anti-CD19 and anti-BCMA Chimeric Antigen Receptor T cells (CAR-T) treatment, which targets B cells and plasma cells, have shown promising early clinical results in the treating various autoimmune diseases. This suggests the importance to targeting both B cells and plasma cells to eliminate pathogenic autoantibodies. However, there is debate about whether CD19 is the most appropriate B cell target. Evidence from B cell malignancies suggests that CD20 CAR-T might result in better survival in diffuse large B-cell lymphoma (DLBCL) than CD19 CAR-T and could even be effective in patients relapsing after CD19 CAR-T therapy. Therefore, we have developed C-CAR168, a novel fully human CD20/BCMA bi-specific autologous CAR-T cell product, for the treatment of autoimmune diseases.

Methods: Cell-based function assays, including cytokine release and cell killing, were used to determine the specificity and reactivity of C-CAR168, and we performed in vivo function studies using immunodeficient mouse xenograft models. A whole genome human membrane proteome array and healthy human tissue immunohistochemistry assays using a rabbit Fc conjugated scFv of C-CAR168 were performed to evaluate the off-tumor toxicity. Potential carcinogenicity risks of C-CAR168 were examined using IL-2 independent growth in vitro and colony formation in the soft-agar assays.

Results: Results of C-CAR168 cell function assays showed antigen specificity and reactivity of C-CAR168, and cell killing experiments demonstrated its specific cytotoxicity to CD20 and/or BCMA expressing target cells. Our results also demonstrated the activation and cell killing of C-CAR168 in the presence of in vitro generated age-associated B cells (ABC), a distinct B cell subset highly expanded in autoimmune diseases and associated with disease activity. In studies using immunodeficient mouse xenograft models, a single dose of C-CAR168 at 1×10⁶, 5×10⁶ and 10×10⁶ CAR-T cells/mouse effectively inhibited the growth of CD20 and BCMA double positive target cells (K562-CD20-BCMA) in B-NDG mice. The in vivo efficacy of C-CAR168 on CD20 or BCMA single positive cells were also evaluated in A549-CD20 xenograft and MM.1S xenograft models, and C-CAR168 had anti-target cell activity at the dose level of 3×10⁶ and 5×10⁶ cells/mouse in both models. The results of membrane proteome array and healthy human tissue immunohistochemistry assays confirmed that C-CAR168 is specific to CD20 and BCMA proteins. In addition, using IL-2 independent growth and colony formation assays, we demonstrated that the transformation or tumorigenicity risk of C-CAR168 cells are minimal.

Conclusion: Based on the promising in vitro/in vivo efficacy results and safety data, C-CAR168 is being evaluated in clinical trials to treat patients with a variety of autoimmune diseases that are refractory to standard therapy.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/c-car168-as-a-novel-anti-cd20-bcma-bispecific-autologous-car-t-therapy-for-the-treatment-of-autoimmune-diseases/