Just like what Penack et al. have reviewed, the unique toxicity profile of CAR-T, including CRS, ICANS, cardiotoxicity, pulmonary toxicity, metabolic complications, secondary macrophage-activation syndrome (sHLH/MAS), and prolonged cytopenia, are also frequently occurring events in clinical-trial widely utilized CD19 CAR-T therapy [74]. This evidence concerns the gene CD19 and macrophage activation syndrome.