Our previous study suggests that CD4 CTLs are important effector cells against high-risk neuroblastoma, but the CD4 CTL mediated-“protective effect” declines over time, in part due to the progressive formation of an immunosuppressive tumor microenvironment (TME) [5] and/or chemotherapy-induced suppression of hematopoiesis [6]. The gene discussed is CD4; the disease is neuroblastoma.