CD4 and cancer: Based on work by Ben Towne Center for Childhood Cancer Research and Fred Hutchinson Cancer Research Center, CAR-T cell product at a defined 1:1 CD4/CD8 ratio and limited effector differentiation offered several advantages including: (i) better correlation between cell dose and CAR-T cell expansion/ persistence, (ii) better prediction and mitigation of toxicity; and (iii) potentially superior therapeutic efficacy in patients (42, 43).