The Impact of Chimeric Antigen Receptor (CAR) T Cell Therapy: Its Potential to Reshape Rheumatology Practice

In recent years, genetically modified T cell therapy, using chimeric antigen receptor (CAR)‑engineered T cells, has revolutionized the field of rheumatology. While CAR T cell therapy is approved by government agencies, including Health Canada, as a standard treatment for B cell lymphoproliferative malignancies, it has also shown remarkable efficacy in refractory cases of rheumatic diseases, including systemic lupus erythematosus, systemic sclerosis, idiopathic inflammatory myopathies, ANCA-associated vasculitis, and rheumatoid arthritis. A single infusion of CAR T cells has demonstrated the potential to induce long-term drug-free remission in most cases. This therapy achieves profound B cell depletion in both blood and tissues—an effect not typically observed with conventional antibody-based B cell-target therapies. Despite its transformative potential, several challenges remain, including questions around long-term safety, high costs, limited accessibility, and the absence of standardized guidelines, which complicate its broader application. Rheumatologists face practical uncertainties, such as determining the optimal timing for treatment, selecting suitable patients, and identifying which diseases might benefit the most from this therapy. This editorial explores the fundamental principles of CAR T cell therapy, highlights the unresolved challenges, and provides insights into how rheumatologists can optimize its use for managing rheumatic diseases. (Please note that this manuscript was written in April 2025. Given the rapid advancements and emerging evidence in this field, there may be updates by the time this article is published.)