After CAR-T for autoimmune disease, most had mild cytokine release, predicted by B cells and IL-6

Design

Retrospective multicentre cohort

Population

108 patients with autoimmune disease treated with autologous CAR-T cells

Primary outcome

Occurrence of cytokine release syndrome and neurotoxicity

Effect

CRS 80% (grade ≥3 1%); B-cell count OR 1.31 (1.06–1.67), IL-6 OR 2.28 (1.30–4.65)

This retrospective cohort pooled 108 patients with autoimmune diseases treated with autologous CAR-T cells at six German centres and one Chinese centre, between 2021 and 2025. Most received CD19-targeted cells; the Chinese patients received CD19-BCMA products.

Cytokine release syndrome occurred in 80%, almost all grade 1 (66%) or grade 2 (13%), with one grade 3 case. Neurotoxicity occurred in 3%, all low grade. Patients who developed cytokine release had higher baseline B-cell counts (median 43 vs 6 cells/μL), IL-6 and CRP. In multivariable analysis, B-cell count (OR 1.31) and IL-6 (OR 2.28) remained associated.

CAR-T is moving out of trials for refractory lupus, myositis and systemic sclerosis. For rheumatologists referring patients, this suggests that cytokine release is expected but usually mild, and that a patient with high B cells and active inflammation at work-up may be at higher risk.

• Tell patients considered for CAR-T that mild cytokine release is common, and severe reactions were rare in this series.
• Record B-cell counts, IL-6 and CRP at work-up; higher values were associated with cytokine release.
• Plan monitoring after infusion with the cellular therapy team, particularly for high-risk profiles.
• Neurotoxicity was uncommon and mild in autoimmune patients in this cohort.

Why it matters

It gives rheumatologists the first numbers to use when counselling patients about CAR-T toxicity.

Don't overread it

A retrospective cohort with mixed CAR-T products; these markers are not yet validated for decisions.

The statistics, in plain English

An OR of 2.28 for IL-6 means higher IL-6 was associated with roughly double the odds of cytokine release. With 108 patients, mixed products and only one grade 3 event, the study cannot predict severe reactions.

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