Local immune effector cell-associated toxicity syndrome in CAR T-cell treated patients with autoimmune disease: an observational study

Abstract

Background: CD19-targeting chimeric antigen receptor (CAR) T-cell therapy has advanced treatment strategies for severe autoimmune diseases such as systemic lupus erythematosus (SLE), systemic sclerosis, and idiopathic inflammatory myopathy. Data regarding side-effects are mostly generated from patients with malignancies, but little is known about autoimmune disease-specific adverse events. This study aimed to describe autoimmune disease-specific adverse events that occur with CAR T-cell therapy.

Methods: In this observational study, patients of any age with autoimmune disease receiving CD19-targeting CAR T-cell therapy in two centres in Germany with a follow-up of at least 30 days were assessed for local organ-specific reactions occurring after CAR T-cell infusion. Observed reactions were documented according to localisation, time of onset, and duration, and were graded for severity (grade 1: spontaneous resolution; grade 2: glucocorticoid treatment due to symptoms lasting >1 week or presence of relevant inner organ involvement; grade 3: prolonged or new hospitalisation; grade 4: intensive care treatment). People with related lived experience were involved in the study design and implementation.

Findings: Between March 1, 2021, and Oct 31, 2024, 39 patients with autoimmune disease were treated with CD19-targeting CAR T cells (20 with SLE, 13 with systemic sclerosis, six with idiopathic inflammatory myopathy). 25 (64%) patients were female and 14 (36%) were male. Median age was 36 years (IQR 22-44). 54 local reactions, which we termed local immune effector cell-associated toxicity syndrome (LICATS), were recorded, affecting 30 (77%) patients with a median time of onset of 10 days (IQR 9-21) from CAR T-cell infusion and a median duration of 11 days (5-14). LICATS exclusively occurred during the B-cell aplasia phase and only involved organs previously affected by the respective autoimmune disease. The most frequently affected organs were the skin (19 [35%] of 54) and the kidneys (12 [22%]). Most cases of LICATS were mild (grade 1: 35 [65%]; grade 2: 16 [30%]). Only three cases were grade 3. All events of LICATS resolved without sequelae.

Interpretation: LICATS is a new form of toxicity in patients with autoimmune disease receiving CD19-targeting CAR T-cell therapy, most likely based on the cleansing of immune cells from the affected organs. It is self-limited, organ-specific, and usually mild in its intensity.

Funding: Deutsche Forschungsgemeinschaft (DFG), German Cancer Aid, Bundesministerium für Bildung und Forschung, European Union, Staedtler Foundation, Lupus Research Alliance, and donations from the Bendel family and the Bleyl family.