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T-cell acute lymphoblastic leukemia (T-ALL) is commonly driven by activating mutations in NOTCH1 that facilitate glutamine oxidation. Here we identify oxidative phosphorylation (OxPhos) as a critical pathway for leukemia cell survival and demonstrate a direct relationship between NOTCH1, elevated OxPhos gene expression, and acquired chemoresistance in pre-leukemic and leukemic models. Disrupting OxPhos with IACS-010759, an inhibitor of mitochondrial complex I, causes potent growth inhibition through induction of metabolic shut-down and redox imbalance in NOTCH1-mutated and less so in NOTCH1-wt T-ALL cells. Mechanistically, inhibition of OxPhos induces a metabolic reprogramming into glutaminolysis. We show that pharmacological blockade of OxPhos combined with inducible knock-down of glutaminase, the key glutamine enzyme, confers synthetic lethality in mice harboring NOTCH1-mutated T-ALL. We leverage on this synthetic lethal interaction to demonstrate that IACS-010759 in combination with chemotherapy containing L-asparaginase, an enzyme that uncovers the glutamine dependency of leukemic cells, causes reduced glutaminolysis and profound tumor reduction in pre-clinical models of human T-ALL. In summary, this metabolic dependency of T-ALL on OxPhos provides a rational therapeutic target.

Background Current strategies for risk stratification of patients with acute myeloid leukemia assign approximately 40% of patients to the intermediate-risk group, where uncertainty about optimal therapy still persists. Objective The objective of this study was to assess the cost effectiveness of a HMGA2 prognostic test based on HMGA2+/HMGA2− expression, which improves genetic risk stratification in acute myeloid leukemia, and compare this test with the current standard of care in Canada. Methods A cost-effectiveness model was developed from the Canadian National Healthcare Service and societal perspective using data from the Quebec Leukemia Cell Bank, published literature, and physician surveys. The model includes a lifetime horizon assessing the HMGA2 test vs. standard of care. Results The HMGA2 test outperformed the standard of care at all time horizons culminating with estimated improvements of 1.92 and 3.12 months in leukemia-free survival and overall survival, respectively. Costs associated with the HMGA2 test were consistently lower, except diagnostic costs, routine medical costs, and costs related to infections and false positives. From a societal perspective, total lifetime costs were $161,358 CAD and $151,908 CAD with the standard of care and the HMGA2 test, respectively. The incremental quality-adjusted life-year gain was 0.138, which led to dominance over the standard of care. Deterministic sensitivity analyses confirmed the results of the base-case scenario. Probabilistic sensitivity analyses revealed that for a willingness-to-pay threshold of $100,000 CAD, the probability of cost effectiveness was 87.19%. Conclusions The HMGA2 test is estimated to improve leukemia-free survival and overall survival outcomes, and yield costs savings from a healthcare system and societal perspective. Electronic supplementary material The online version of this article (10.1007/s40258-019-00503-5) contains supplementary material, which is available to authorized users.

While oncogenes promote tumorigenesis, they also induce deleterious cellular stresses, such as apoptosis, that cancer cells must combat by coopting adaptive responses. Whether tumor suppressor gene haploinsufficiency leads to such phenomena and their mechanistic basis is unclear. Here, we demonstrate that elevated levels of the anti-apoptotic factor, CASP8 and FADD-like apoptosis regulator (CFLAR), promotes apoptosis evasion in acute myeloid leukemia (AML) cells haploinsufficient for the cut-like homeobox 1 (CUX1) transcription factor, whose loss is associated with dismal clinical prognosis. Genome-wide CRISPR/Cas9 screening identifies CFLAR as a selective, acquired vulnerability in CUX1-deficient AML, which can be mimicked therapeutically using inhibitor of apoptosis (IAP) antagonists in murine and human AML cells. Mechanistically, CUX1 deficiency directly alleviates CUX1 repression of the CFLAR promoter to drive CFLAR expression and leukemia survival. These data establish how haploinsufficiency of a tumor suppressor is sufficient to induce advantageous anti-apoptosis cell survival pathways and concurrently nominate CFLAR as potential therapeutic target in these poor-prognosis leukemias., Cut-like homeobox 1 (CUX1) is a haploinsufficient tumor suppressor commonly inactivated in acute myeloid leukemia and high-risk myelodysplasia. Here, in a genetically modified murine model, the authors show that CUX1 deficiency impairs apoptosis leading to leukemia when combined with mutant Flt3-ITD.

Acute promyelocytic leukemia (APL) is a medical emergency because of associated lethal early bleeding, a condition preventable by prompt diagnosis and therapeutic intervention. The mechanisms underlying the hemostatic anomalies of APL are not completely elucidated. RNA-sequencing-based characterization of APL (n = 30) was performed and compared to that of other acute myeloid leukemia (n = 400) samples and normal promyelocytes. Perturbations in the transcriptome of coagulation and fibrinolysis-related genes in APL extend beyond known culprits and now include Thrombin, Factor X and Urokinase Receptor. Most intriguingly, the Podoplanin (PDPN) gene, involved in platelet aggregation, is aberrantly expressed in APL promyelocytes and is the most distinctive transcript for this disease. Using an antibody panel optimized for AML diagnosis by flow cytometry, we also found that PDPN was the most specific surface marker for APL, and that all-trans retinoic acid therapy rapidly decreases its expression. Functional studies showed that engineered overexpression of this gene in human leukemic cells causes aberrant platelet binding, activation and aggregation. PDPN-expressing primary APL cells, but not PDPN-negative primary leukemias, specifically induce platelet binding, activation and aggregation. Finally, PDPN expression on leukemia cells in a xenograft model was associated with thrombocytopenia and prolonged bleeding time in vivo. Together our results suggest that PDPN may contribute to the hemostatic perturbations found in APL.

In acute myeloid leukemia (AML), risk stratification based on cytogenetics and mutation profiling is essential but remains insufficient to select the optimal therapy. Accurate biomarkers are needed to improve prognostic assessment. We analyzed RNA sequencing and survival data of 430 AML patients and identified HMGA2 as a novel prognostic marker. We validated a quantitative PCR test to study the association of HMGA2 expression with clinical outcomes in 358 AML samples. In this training cohort, HMGA2 was highly expressed in 22.3% of AML, mostly in patients with intermediate or adverse cytogenetics. High expression levels of HMGA2 (H + ) were associated with a lower frequency of complete remission (58.8% vs 83.4%, P 0.001), worse 3-year overall survival (OS, 13.2% vs 43.5%, P 0.001) and relapse-free survival (RFS, 10.8% vs 44.2%, P 0.001). A positive HMGA2 test also identified a subgroup of patients unresponsive to standard treatments. Multivariable analyses showed that H + was independently associated with significantly worse OS and RFS, including in the intermediate cytogenetic risk category. These associations were confirmed in a validation cohort of 260 patient samples from the UK NCRI AML17 trial. The HMGA2 test could be implemented in clinical trials developing novel therapeutic strategies for high-risk AML.

Identification of MYC mutations in acute myeloid leukemias with NUP98 – NSD1 translocations

Using next-generation sequencing of primary acute myeloid leukemia (AML) specimens, we identified to our knowledge the first unifying genetic network common to the two subgroups of KMT2A (MLL)-rearranged leukemia, namely having MLL fusions or partial tandem duplications. Within this network, we experimentally confirmed upregulation of the gene with the most subtype-specific increase in expression, LOC100289656, and identified cryptic MLL fusions, including a new MLL-ENAH fusion. We also identified a subset of MLL fusion specimens carrying mutations in SPI1 accompanied by inactivation of its transcriptional network, as well as frequent RAS pathway mutations, which sensitized the leukemias to synthetic lethal interactions between MEK and receptor tyrosine kinase inhibitors. This transcriptomics-based characterization and chemical interrogation of human MLL-rearranged AML was a valuable approach for identifying complementary features that define this disease.

Using murine Moloney leukemia virus (MMLV)-based proviral insertional mutagenesis, we previously showed a preferential targeting of a small region in the Hoxa gene locus in E2A-PBX1-induced lymphoid leukemia resulting in the overexpression of several Hoxa genes including Hoxa10, Hoxa9 and Hoxa7. This observation suggested a functional interaction between Hox gene overexpression and E2A-PBX1 in lymphoid tumors. To further explore this possibility, we generated a series of compound E2A-PBX1 x Hox transgenic mice and tested the genetic interaction between these genes in the generation of lymphoid leukemia in vivo. Results presented in this report show that the onset of T-cell leukemia is significantly accelerated in E2A-PBX1 x Hoxb4 compound transgenic animals when compared with control E2A-PBX1 or Hoxb4 littermates. Hoxa9 appears less potent than Hoxb4 to accelerate E2A-PBX1-induced T-cell leukemia in mice. E2A-PBX1-induced T-cell leukemias express much higher levels of Hoxa genes than MMLV-induced counterparts, possibly suggesting a contribution of these genes to T-cell transformation by E2A-PBX1. Collectively, these data provide the first genetic evidence showing oncogenic collaboration between E2A-PBX1 and a Hox gene in lymphoid malignancies in vivo and document the specific deregulation of a subgroup of Hoxa genes in these leukemias.

Stem cells have acquired a golden glow in the past few years as they represent possible tools for reversing the damage wreak on organs. These cells are found not only in major regenerative tissues, such as the epithelia, blood and testes, but also in 'static tissues', such as the nervous system and liver, where they play a central role in tissue growth and maintenance. The mechanism by which stem cells maintain populations of highly differentiated, short-lived cells seems to involve a critical balance between alternate fates: daughter cells either maintain stem cell identity or initiate differentiation. Recent studies in lower organisms have unveiled the regulatory mechanisms of asymmetric stem cell divisions. In these models, the surrounding environment likely provides key instructive signals for the cells to choose one fate over another. Our understanding now extends to the intrinsic mechanisms of cell polarity that influence asymmetrical stem cell divisions. This article focuses on the genetic determinants of asymmetric stem cell divisions in lower organisms as a model for studying the process of self-renewal of mammalian hematopoietic stem cells.

The capacity for sustained self-renewal--the generation of daughter cells having the same regenerative properties as the parent cell--is the defining feature of hematopoietic stem cells (HSCs). Strong evidence exists that self-renewal of HSC is under extrinsic biological control in vivo. A variety of cytokines, morphogenic ligands and associated signaling components influence self-renewal in culture and in vivo. Specific homeobox transcription factors act as powerful intrinsic agonists of HSC self-renewal in vitro and in vivo when supplied either as transduced cDNAs or as externally delivered proteins. These findings provide tools for deepening our knowledge of mechanism and for achievement of clinically useful levels of HSC expansion.

Hematopoietic stem cells (HSCs) can self-renew extensively after transplantation. The conditions supporting their in vitro expansion are still being defined. Retroviral overexpression of the human homeobox B4 (HOXB4) gene in mouse bone marrow cells enables over 40-fold expansion of HSCs in vitro. To circumvent the requirement for retroviral infection, we used recombinant human TAT-HOXB4 protein carrying the protein transduction domain of the HIV transactivating protein (TAT) as a potential growth factor for stem cells. HSCs exposed to TAT-HOXB4 for 4 d expanded by about four- to sixfold and were 8-20 times more numerous than HSCs in control cultures, indicating that HSC expansion induced by TAT-HOXB4 was comparable to that induced by the human HOXB4 retrovirus during a similar period of observation. Our results also show that TAT-HOXB4-expanded HSC populations retain their normal in vivo potential for differentiation and long-term repopulation. It is thus feasible to exploit recombinant HOXB4 protein for rapid and significant ex vivo expansion of normal HSCs.

We report a series of 37 consecutive patients with multiple myeloma (MM) who received an allograft between 1990 and 2000 at our institution. Median age was 47 years, and nearly 70% of patients were Durie-Salmon stage III. A median of five cycles of chemotherapy were given before transplant, with a median interval between diagnosis and transplant of 9.3 months. We report a nonrelapse mortality rate of 22% with a median follow-up period of 40 months, whereas complete remission (CR) rate at 12 months is estimated at 57%. Treatment failure rate and overall survival at 40 months are estimated at 52% and 32%, respectively. The number of chemotherapy cycles prior to allotransplantation achieved borderline statistical significance as a poor prognosis factor for overall survival (P = 0.05), while the presence of chronic graft-versus-host disease (cGVHD) was significantly correlated with CR achievement (P = 0.036). Our study confirms that early allografting in MM can yield toxicity rates significantly lower than those associated with historical cohorts, and supports the hypothesis that cumulative chemotoxicity has a negative influence on mortality and survival rates. More importantly, our study clearly demonstrates an association between cGVHD and CR and brings further evidence in favor of a graft-versus-myeloma effect.

Acute myeloid leukemia (AML) is associated with poor clinical outcome and the development of more effective therapies is urgently needed. G protein-coupled receptors (GPCRs) represent attractive therapeutic targets, accounting for approximately 30% of all targets of marketed drugs. Using next-generation sequencing, we studied the expression of 772 GPCRs in 148 genetically diverse AML specimens, normal blood and bone marrow cell populations as well as cord blood-derived CD34-positive cells. Among these receptors, 30 are overexpressed and 19 are downregulated in AML samples compared with normal CD34-positive cells. Upregulated GPCRs are enriched in chemokine (CCR1, CXCR4, CCR2, CX3CR1, CCR7 and CCRL2), adhesion (CD97, EMR1, EMR2 and GPR114) and purine (including P2RY2 and P2RY13) receptor subfamilies. The downregulated receptors include adhesion GPCRs, such as LPHN1, GPR125, GPR56, CELSR3 and GPR126, protease-activated receptors (F2R and F2RL1) and the Frizzled family receptors SMO and FZD6. Interestingly, specific deregulation was observed in genetically distinct subgroups of AML, thereby identifying different potential therapeutic targets in these frequent AML subgroups.

We present the case of a 28-year-old female patient with advanced myelodysplastic syndrome. Her BM examination at diagnosis showed the presence of 16% blasts and multi-lineage dysplasia, findings consistent with refractory anemia with excess blasts-2 (RAEB-2). Cytogenetic analysis revealed a deletion 5q and the rare translocation t(3;12)(q26;p13) with rearrangement of the ecotropic viral integration-1 gene (EVI1) by FISH. An allogeneic hematopoietic SCT (HSCT) was considered to be urgent due to the high-risk nature of her disease. Unfortunately, neither a family nor a matched unrelated donor was available. We therefore decided to proceed with a cord blood transplantation from a 6/6 HLA-matched donor. The unit contained a total nucleated cell dose of 3.87 × 107/kg; both donor and recipient were seronegative for CMV. The preparative regimen included fractioned TBI (12 Gy), CY (120 mg/kg) given over two days and fludarabine (75 mg/m2) in three doses. GVHD prophylaxis consisted of tacrolimus (beginning on day −3) and mycophenolate mofetil (as of day +1).

Late acute renal failure due to bilateral kidney infiltration by ALL as single manifestation of relapse after allogeneic transplantation