LAUSR

Kinase signaling fuels growth of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Yet its role in leukemia initiation is unclear and has not been shown in primary human hematopoietic cells. We previously described activating mutations in interleukin-7 receptor alpha (IL7RA) in poor-prognosis “ph-like” BCP-ALL. Here we show that expression of activated mutant IL7RA in human CD34 + hematopoietic stem and progenitor cells induces a preleukemic state in transplanted immunodeficient NOD/LtSz- scid IL2Rγ null mice, characterized by persistence of self-renewing Pro-B cells with non-productive V(D)J gene rearrangements. Preleukemic CD34 + CD10 high CD19 + cells evolve into BCP-ALL with spontaneously acquired Cyclin Dependent Kinase Inhibitor 2 A ( CDKN2A ) deletions, as commonly observed in primary human BCP-ALL. CRISPR mediated gene silencing of CDKN2A in primary human CD34 + cells transduced with activated IL7RA results in robust development of BCP-ALLs in-vivo. Thus, we demonstrate that constitutive activation of IL7RA can initiate preleukemia in primary human hematopoietic progenitors and cooperates with CDKN2A silencing in progression into BCP-ALL. Activating mutations in Interleukin-7 receptor alpha (IL7Ra) have been reported in B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) but its role in leukaemogenesis is not clear. Here, the authors show that activation of IL7Ra in primary human hematopoietic progenitors initiates preleukaemia and cooperates with CDKN2A silencing to develop BCP-ALL.