Background

Multiple sclerosis, myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), generalized myasthenia gravis, and idiopathic inflammatory myopathies are conditions in which the immune system attacks the central nervous system, neuromuscular junctions, or muscles, causing disability. B cells not only produce autoantibodies but also contribute to antigen presentation and inflammation amplification. While anti-CD20 antibodies and immunosuppressants can reduce disease activity, many patients still have residual pathogenic B cells in tissues or experience relapse after treatment discontinuation.

CD19 chimeric antigen receptor T cells (CAR-T) have emerged as a candidate for resetting the immune system by deeply eliminating B cells across a broader developmental spectrum. However, conventional autologous CAR-T requires T cells to be harvested from patients, genetically modified, expanded in culture, and then reinfused. This process takes several weeks, is costly, and often requires lymphodepleting chemotherapy with fludarabine and cyclophosphamide prior to administration.

Key Findings

Researchers from Tongji Hospital at Huazhong University of Science and Technology administered a single intravenous dose of non-replicating, self-inactivating lentiviral vector to deliver CD19-targeting CAR genes directly into patients' T cells. No ex vivo cell manipulation or lymphodepleting chemotherapy was performed. The phase 1 study published in the New England Journal of Medicine included 16 patients with refractory conditions: 7 with progressive multiple sclerosis, 3 with MOGAD, 3 with generalized myasthenia gravis, and 3 with idiopathic inflammatory myopathy.

CAR-T production and proliferation were confirmed in all patients, with cell counts peaking approximately 11 days after administration. Over 99.7% of CAR-positive cells detected were of typical T cell origin. B cells were deeply depleted in peripheral blood, bone marrow, and cerebrospinal fluid, suggesting the potential to target immune responses within the blood-brain barrier. B cells began to reappear after a median of about 2 months, with the reconstituted population dominated by antigen-naive B cells.

The median follow-up period was 6 months. No new gadolinium-enhancing lesions were observed in any of the 7 multiple sclerosis patients, and indicators of walking, fine motor skills, and cognitive processing, as well as neurofilament light chain and kappa free light chain levels, showed improvement. The myasthenia gravis group showed a reduction of over 60% in clinical scale scores at 6 months, and acetylcholine receptor antibodies also decreased. In the inflammatory myopathy group, creatine kinase and myoglobin levels decreased by more than 60%. In 2 out of 3 MOGAD patients, antibody titers decreased by the third month.

Implications and Outlook

These results suggest the potential to shift from patient-specific cell therapy to a gene therapy platform using standardized vectors administered in vivo. Particularly, the depletion of B cells in cerebrospinal fluid provides evidence for targeting the central nervous system immune compartment, which has been difficult to reach with peripheral blood-focused therapies.

Safety signals were manageable at this early stage. Grade 1 cytokine release syndrome occurred in 11 of the 16 patients between 5 and 28 days post-administration, but all resolved within 2 weeks. Immune effector cell-associated neurotoxicity syndrome, hypotension, and hypoxia were not observed. Vector-related proteins fell below detectable levels by day 4, and no abnormal clonal expansion associated with oncogenes was detected in initial genomic insertion site analyses.

However, this was a phase 1 study with only 16 patients, and the number of patients per disease ranged from 3 to 7. It is difficult to exclude natural variability or the effects of concomitant therapies, and long-term observation is required to determine whether the nerve damage itself has recovered. Due to the characteristics of lentiviral vectors, insertion mutations, abnormal T cell clones, and infection risks must be monitored over several years. Appropriate dosing per disease and the possibility of re-administration also remain to be clarified in subsequent controlled trials.