Besides, in two studies investigating the clinical effects of anti-CD19 CAR T-cell products with defined CD4:CD8 ratio in R/R B-ALL (42) and NHL (73), Turtle and coworkers observed superior CAR T-cell peak levels in individuals receiving higher (i.e., 2 ×106 vs. 2 ×105/kg) CAR T-cell dose, likely accounting for the correlation between numbers of infused CAR T-cell and severe toxicity (40, 41, 76). Here, CD19 is linked to acute lymphoblastic leukemia.