High frequencies of leukemia stem cells in poor-outcome childhood precursor-B acute lymphoblastic leukemias

Abstract

In order to develop a xenograft model to determine the efficacy of new therapies against primary human precursor-B acute lymphoblastic leukemia (ALL) stem cells (LSCs), we used the highly immunodeficient non-obese diabetic (NOD).Cg-PrkdcscidIL2rgtmlWjl/SzJ (NOD-severe combined immune deficient (scid) IL2rg−/−) mouse strain. Intravenous transplantation of 2 of 2 ALL cell lines and 9 of 14 primary ALL cases generated leukemia-like proliferations in recipient mice by 1–7 months after transplant. Leukemias were retransplantable, and the immunophenotypes, gene rearrangements and expression profiles were identical or similar to those of the original primary samples. NOD-scid mice transplanted with the same primary samples developed similar leukemias with only a slightly longer latency than did NOD-scid-IL2Rg−/− mice. In this highly sensitive NOD-scid-IL2Rg−/−-based assay, 1–100 unsorted primary human ALL cells from five of five tested patients, four of whom eventually experienced leukemia relapse, generated leukemias in recipient mice. This very high frequency of LSCs suggests that a hierarchical LSC model is not valuable for poor-outcome ALL.

Interleukin-27 inhibits pediatric B-acute lymphoblastic leukemia cell spreading in a preclinical model

“…However, immunophenotypic analysis showed that engrafted B-ALL cells, compared with the original sample, maintained CD45 and CD10, but not CD19 expression. The mechanism underlying the absence of CD19 surface expression in engrafted human cells may be ascribed to posttranscriptional events, as described 26 and/or related to their acquisition of a more immature phenotype possibly induced by microenvironmental conditions. In addition, it was suggested that ETV6-RUNX1-positive cells capable of reconstituting leukemia upon transplantation to NOD-SCID mice have the CD19 À phenotype.…”

“…[24][25][26] Thus, six early pre (CD19 þ CD10 þ ) B-ALL cell suspensions (Pt 3, 9, 15, 16, 17 and 18) were injected i.v. in two groups of five animals each (controls and IL-27-treated mice) and killed 6-8 weeks later when signs of poor health became evident in controls.…”

Flow minimal residual disease monitoring of candidate leukemic stem cells defined by the immunophenotype, CD34+CD38lowCD19+ in B-lineage childhood acute lymphoblastic leukemia

“…Currently, much debate surrounds LSCs in childhood ALL with evidence identifying candidate LSCs in both rare, immature populations as well as conversely, across several immunophenotypically distinct groups. 9,10,[18][19][20][21] It is unlikely that we can clinically exploit current evidence to effectively re-direct flow cytometric MRD monitoring towards the LSC compartment until the immunophenotype of the cells which maintain the leukemia are more clearly defined. …”

Very high frequencies of leukaemia‐initiating cells in precursor T‐acute lymphoblastic leukaemia may be obscured by cryopreservation

“…In precursor T-acute lymphoblastic leukaemia (ALL), the frequency of LSCs (defined as cells that initiate leukaemic engraftment in a xenograft recipient) is reported to range from one in 10 5 -10 7 following intravenous injection into non-obese diabetic severe combined immunodeficient (NOD/SCID; NS) mice (Cox et al, 2007;Chiu et al, 2010), or one in 10 3 -10 5 where the more immunodeficient NOD.Cg-Prkdc scid Il2rg tm1Wjl /SzJ (NSG) strain is used (Armstrong et al, 2009;Chiu et al, 2010). In precursor B-ALL, NS xenograft-initiating cell frequencies of one in 10 5 -10 7 have been reported (Cobaleda et al, 2000), with higher frequencies observed following intrafemoral transplant into NSG mice (one in 40-10 3 ; le Viseur et al, 2008;Rehe et al, 2013) or where cells from chemorefractory patients are used (one in 10-10 2 ; Morisot et al, 2010). The cellular organization of ALL has variably been argued to be hierarchical (Cobaleda et al, 2000;Cox et al, 2007;Hong et al, 2008) or non-hierarchical (le Viseur et al, 2008Diamanti et al, 2012;Rehe et al, 2013), the latter being based on the identification of LSCs in all of the variable immunophenotypic sub-populations of the disease.…”