This preclinical study evaluated KITE-363, a dual-targeting anti-CD19/CD20 CAR T-cell therapy in patients with myasthenia gravis (MG) or multiple sclerosis (MS). 

B-cells drive pathogenesis of neuroinflammatory autoimmune diseases through several key mechanisms. B-cell depleting agents, including chimeric antigen receptor (CAR) T-cells, have demonstrated potential for reestablishing immune tolerance and achieving rapid, durable remission. Dual-targeting of CD19 and CD20, variably expressed during B-cell maturation, may enhance efficacy over single-antigen approaches. Moreover, eliminating potentially pathogenic CD20⁺ T-cells and NK-cells may offer additional therapeutic benefits in autoimmune diseases. KITE-363 is an anti-CD19/CD20 CAR T-cell therapy incorporating both CD28 and 41BB costimulatory domains and is currently in Phase 1 clinical trials for relapsed/refractory B-cell lymphoma (NCT04989803) and refractory rheumatic autoimmune diseases (NCT07038447).

CD19 and CD20 expression on B-cells and T-cells from patients with MG or MS was analyzed by flow cytometry. Patient-derived anti-CD19/CD20 CAR T-cell products (KITE-363) were generated using a bicistronic lentiviral vector encoding anti-CD19 CAR (FMC63-CD28ζ) and anti-CD20 CAR (CD20-41BBζ). Immunophenotyping and in vitro functional assessments were performed.

In patients with MG or MS, most B-cells variably expressed both antigens (CD19⁺CD20⁺). Single-antigen positive CD19⁺CD20^– plasmablasts, CD19^–CD20⁺ double negative (IgD^–CD27^–) B-cells, CD20⁺ T-cells, and NK-cells were also detected. Patient-derived KITE-363 products exhibited high expression of both CARs. Antigen-specific functionality was demonstrated through cytokine secretion, proliferation, and cytotoxicity against CD19⁺ and/or CD20⁺ cell lines, autologous B-cells, and T-cells.

Highly variable CD19 and CD20 expression on B-cell subsets and potent antigen-specific depletion of B-cells and CD20⁺ T-cells provide robust evidence for clinical development of KITE-363 in B-cell-mediated neuroinflammatory diseases. KITE-363 aims to comprehensively eliminate pathogenic B-cells and other immune cells with dual-antigen CD19/CD20 targeting and optimized co-stimulation to achieve durable, drug-free remission. A Phase 1 study is underway to evaluate the safety and efficacy of KITE-363 in refractory autoimmune neuroinflammatory diseases.