In addition, although this study provides evidence that low-dose IL-21 treatment prolongs the survival of AML mice in syngeneic and AML PDX models, systemic IL-21 treatment may not only act on LSCs but most likely also affect other IL-21R-expressing cell types such as CD8+ T cells and NK cells, and thus improve immune control of AML. This evidence concerns the gene IL21R and acute myeloid leukemia.