For example, in a clinical trial of pediatric SLE, 20 patients treated with CD19–CAR‐T achieved clinical improvement, and the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI‐2K) score of 15 patients fell below 4 within 3 months [238]. This evidence concerns the gene CD19 and systemic lupus erythematosus.