Rheumatologic complications of CAR-T Cell therapy. Experience of a single center

Introduction: Chimeric Antigen Receptor T-cell (CAR-T) therapy has emerged as a promising treatment for hematological malignancies. However, its association with immune-related complications such as rheumatic complications, is not well defined. Methods: We conducted a retrospective study to analyze rheumatic complications in 310 patients treated with CAR-T therapy at a single center from January 2020 to May 2024. Results: We identified six patients (1.9 %) who developed rheumatic complications, including rheumatoid arthritis (RA)-like manifestations with biopsy-proven nodules, palindromic rheumatism, myositis, necrotizing fasciitis, and osteonecrosis (ON). Symptoms appeared between 2 to 11 weeks after therapy, with inflammatory arthritis manifesting later. Notably, 2 patients developed RA-like arthritis with subcutaneous nodulosis, while others presented with transient arthritis flares, severe soft tissue and joint involvement, such as pseudo-podagra and ON. Imaging findings and biopsies confirmed the diagnoses. Treatment included glucocorticoids, hydroxychloroquine, and nonsteroidal anti-inflammatory drugs, with variable responses. Conclusions: Clinicians should be aware of these potential complications to ensure prompt diagnosis and management. Further research is needed to elucidate the mechanisms underlying these autoimmune phenomena and to establish standardized treatment protocols.