In a study of CD-19 CART for relapsed refractory B-cell lymphoma, patients who developed severe infections had elevated IL-6 levels on the day of the event compared with the CRS-only cohort (median 2243 pg/mL versus 64 pg/mL, P = 0.03) (Rejeski et al., 2023). This evidence concerns the gene CD19 and B-cell non-Hodgkin lymphoma.