bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2021‒09‒05
forty papers selected by
Paolo Gallipoli
Barts Cancer Institute, Queen Mary University of London

  1. Leukemia. 2021 Aug 30.
      Acute myeloid leukemia (AML) is considered a poor prognosis malignancy where patients exhibit altered glucose metabolism and stem cell signatures that contribute to AML growth and maintenance. Here, we report that the epigenetic factor, Ten-Eleven Translocation 3 (TET3) dioxygenase is overexpressed in AML patients and functionally validated human leukemic stem cells (LSCs), is required for leukemic growth by virtue of its regulation of glucose metabolism in AML cells. In human AML cells, TET3 maintains 5-hydroxymethylcytosine (5hmC) epigenetic marks and expression of early myeloid progenitor program, critical glucose metabolism and STAT5A signaling pathway genes, which also positively correlate with TET3 expression in AML patients. Consequently, TET3 depletion impedes hexokinase activity and L-Lactate production in AML cells. Conversely, overexpression of TET3 in healthy human hematopoietic stem progenitors (HSPCs) upregulates the expression of glucose metabolism, STAT5A signaling and AML associated genes, and impairs normal HSPC lineage differentiation in vitro. Finally, TET3 depletion renders AML cells highly sensitive to blockage of the TET3 downstream pathways glycolysis and STAT5 signaling via the combination of 2-Deoxy-D-glucose and STAT5 inhibitor which preferentially targets AML cells but spares healthy CD34+ HSPCs.
  2. Leukemia. 2021 Aug 31.
      Ubiquitin-specific peptidase 15 (USP15) is a deubiquitinating enzyme implicated in critical cellular and oncogenic processes. We report that USP15 mRNA and protein are overexpressed in human acute myeloid leukemia (AML) as compared to normal hematopoietic progenitor cells. This high expression of USP15 in AML correlates with KEAP1 protein and suppression of NRF2. Knockdown or deletion of USP15 in human and mouse AML models significantly impairs leukemic progenitor function and viability and de-represses an antioxidant response through the KEAP1-NRF2 axis. Inhibition of USP15 and subsequent activation of NRF2 leads to redox perturbations in AML cells, coincident with impaired leukemic cell function. In contrast, USP15 is dispensable for human and mouse normal hematopoietic cells in vitro and in vivo. A preclinical small-molecule inhibitor of USP15 induced the KEAP1-NRF2 axis and impaired AML cell function, suggesting that targeting USP15 catalytic function can suppress AML. Based on these findings, we report that USP15 drives AML cell function, in part, by suppressing a critical oxidative stress sensor mechanism and permitting an aberrant redox state. Furthermore, we postulate that inhibition of USP15 activity with small molecule inhibitors will selectively impair leukemic progenitor cells by re-engaging homeostatic redox responses while sparing normal hematopoiesis.
  3. Blood Adv. 2021 Sep 14. 5(17): 3279-3289
      The tyrosine-protein phosphatase nonreceptor type 11 (PTPN11) is an important regulator of RAS signaling and frequently affected by mutations in patients with acute myeloid leukemia (AML). Despite the relevance for leukemogenesis and as a potential therapeutic target, the prognostic role is controversial. To investigate the prognostic impact of PTPN11 mutations, we analyzed 1529 adult AML patients using next-generation sequencing. PTPN11 mutations were detected in 106 of 1529 (6.93%) patients (median VAF: 24%) in dominant (36%) and subclonal (64%) configuration. Patients with PTPN11 mutations were associated with concomitant mutations in NPM1 (63%), DNMT3A (37%), and NRAS (21%) and had a higher rate of European LeukemiaNet (ELN) favorable cytogenetics (57.8% vs 39.1%; P < .001) and higher white blood cell counts (P = .007) compared with PTPN11 wild-type patients. In a multivariable analysis, PTPN11 mutations were independently associated with poor overall survival (hazard ratio [HR]: 1.75; P < .001), relapse-free survival (HR: 1.52; P = .013), and a lower rate of complete remission (odds ratio: 0.46; P = .008). Importantly, the deleterious effect of PTPN11 mutations was confined predominantly to the ELN favorable-risk group and patients with subclonal PTPN11 mutations (HR: 2.28; P < .001) but not found with dominant PTPN11 mutations (HR: 1.07; P = .775), presumably because of significant differences within the rate and spectrum of associated comutations. In conclusion, our data suggest an overall poor prognostic impact of PTPN11 mutations in AML, which is significantly modified by the underlying cytogenetics and the clonal context in which they occur.
  4. Eur J Med Chem. 2021 Aug 17. pii: S0223-5234(21)00625-5. [Epub ahead of print]225 113776
      FMS-like tyrosine kinase 3 (FLT3) with an internal tandem duplication (ITD) mutation has been validated as a driver lesion and a therapeutic target for acute myeloid leukemia (AML). Currently, several potent small-molecule FLT3 kinase inhibitors are being evaluated or have completed evaluation in clinical trials. However, many of these inhibitors are challenged by the secondary mutations on kinase domain, especially the point mutations at the activation loop (D835) and gatekeeper residue (F691). To overcome the resistance challenge, we identified a novel series of imidazo[1,2-a]pyridine-thiophene derivatives from a NIMA-related kinase 2 (NEK2) kinase inhibitor CMP3a, which retained inhibitory activities on FTL3-ITDD835V and FLT3-ITDF691L. Through this study, we identified the imidazo[1,2-a]pyridine-thiophene derivatives as type-I inhibitors of FLT3. Moreover, we observed compound 5o as an inhibitor displaying equal anti-proliferative activities against FLT3-ITD, FTL3-ITDD835Y and FLT3-ITDF691L driven acute myeloid leukemia (AML) cell lines. Meanwhile, the apoptotic effects of compound supported its mechanism of anti-proliferative action. These results indicate that the imidazo[1,2-a]pyridine-thiophene scaffold is promising for targeting acquired resistance caused by FLT3 secondary mutations and compound 5o is an interesting lead in this direction.
    Keywords:  AML; FLT3; Imidazole pyridine; Mutants
  5. J Hematol Oncol. 2021 08 28. 14(1): 133
      BACKGROUND: Most older patients with acute myeloid leukemia (AML) who attain morphologic remission with intensive chemotherapy (IC) will eventually relapse and post-relapse prognosis is dismal. In the pivotal QUAZAR AML-001 trial, oral azacitidine maintenance therapy significantly prolonged overall survival by 9.9 months (P < 0.001) and relapse-free survival by 5.3 months (P < 0.001) compared with placebo in patients with AML in first remission after IC who were not candidates for transplant. Currently, the QUAZAR AML-001 trial provides the most comprehensive safety information associated with oral azacitidine maintenance therapy. Reviewed here are common adverse events (AEs) during oral azacitidine treatment in QUAZAR AML-001, and practical recommendations for AE management based on guidance from international cancer consortiums, regulatory authorities, and the authors' clinical experience treating patients in the trial.METHODS: QUAZAR AML-001 is an international, placebo-controlled randomized phase 3 study. Patients aged ≥ 55 years with AML and intermediate- or poor-risk cytogenetics at diagnosis, who had attained first complete remission (CR) or CR with incomplete blood count recovery (CRi) within 4 months before study entry, were randomized 1:1 to receive oral azacitidine 300 mg or placebo once-daily for 14 days in repeated 28-day cycles. Safety was assessed in all patients who received ≥ 1 dose of study drug.
    RESULTS: A total of 469 patients received oral azacitidine (n = 236) or placebo (n = 233). Median age was 68 years. Patients received a median of 12 (range 1-80) oral azacitidine treatment cycles or 6 (1-73) placebo cycles. Gastrointestinal AEs were common and typically low-grade. The most frequent grade 3-4 AEs during oral azacitidine therapy were hematologic events. AEs infrequently required permanent discontinuation of oral azacitidine (13%), suggesting they were effectively managed with use of concomitant medications and oral azacitidine dosing modifications.
    CONCLUSION: Oral azacitidine maintenance had a generally favorable safety profile. Prophylaxis with antiemetic agents, and blood count monitoring every other week, are recommended for at least the first 2 oral azacitidine treatment cycles, and as needed thereafter. Awareness of the type, onset, and duration of common AEs, and implementation of effective AE management, may maximize treatment adherence and optimize the survival benefits of oral azacitidine AML remission maintenance therapy. Trial registration This trial is registered on NCT01757535 as of December 2012.
    Keywords:  CC-486; Maintenance; Oral azacitidine; Safety
  6. Clin Cancer Res. 2021 Sep 01. pii: clincanres.2574.2021. [Epub ahead of print]
      Cellular therapies have demonstrated limited efficacy thus far in acute myeloid leukemia (AML). A recent study shows that mTORC1 activation down-regulated CXCR4 reducing marrow infiltration of EpCAM-targeting CAR-T cells in AML. Abrogating mTOR signaling by co-treatment with mTOR inhibitors during IL2-mediated ex vivo expansion upregulated CXCR4 and bolstered bone marrow migration and AML elimination by CAR-T cells.
  7. Blood Adv. 2021 Sep 01. pii: bloodadvances.2020003958. [Epub ahead of print]
      Acute myeloid leukemia (AML) is the commonest acute leukemia in adults. Disease heterogeneity is well-documented and patient stratification determines treatment decisions. Patient-derived xenografts (PDXs) of risk-stratified AMLs are crucial for studying AML biology and testing novel therapeutics. Despite recent advances in PDX modeling of AML, reproducible engraftment of human AML is mainly limited to high-risk (HR) cases, with inconsistent or very protracted engraftment observed for favorable-risk (FR) and intermediate-risk (IR) patients. We have characterized the engraftment robustness/kinetics in NSGS mice of 28 AML patients grouped according to molecular/cytogenetic classification, and have assessed whether the orthotopic co-administration of patient-matched bone marrow mesenchymal stromal cells (BM-MSCs) improves AML engraftment. PDX event-free survival correlated well with the predictable prognosis of risk-stratified AML patients. The majority (85%-94%) of the mice were engrafted in BM independently of the risk group, although HR-AML patients showed engraftment levels significantly superior to those of FR- and IR-AML patients. Importantly, the engraftment levels observed in NSGS mice by week 6 remained stable overtime. Serial transplantation and long-term culture-initiating cell (LTC-IC) assays revealed long-term engraftment limited to HR-AML patients, fitter leukemia-initiating cells (LICs) in HR- than in FR- or IR-AML samples, and the presence of AML-LICs in the CD34- leukemic fraction, regardless the risk group. Finally, orthotopic co-administration of patient-matched BM-MSCs with AML cells resulted dispensable for BM engraftment levels but favored peripheralization of engrafted AML cells. This comprehensive characterization of human AML engraftment in NSGS mice offers a valuable platform for in vivo testing of targeted therapies in risk-stratified AML patient samples.
  8. Leukemia. 2021 Sep 03.
      Myeloproliferative neoplasms (MPN) show dysregulated JAK2 signaling. JAK2 inhibitors provide clinical benefits, but compensatory activation of MAPK pathway signaling impedes efficacy. We hypothesized that dual targeting of JAK2 and ERK1/2 could enhance clone control and therapeutic efficacy. We employed genetic and pharmacologic targeting of ERK1/2 in Jak2V617F MPN mice, cells and patient clinical isolates. Competitive transplantations of Jak2V617F vs. wild-type bone marrow (BM) showed that ERK1/2 deficiency in hematopoiesis mitigated MPN features and reduced the Jak2V617F clone in blood and hematopoietic progenitor compartments. ERK1/2 ablation combined with JAK2 inhibition suppressed MAPK transcriptional programs, normalized cytoses and promoted clone control suggesting dual JAK2/ERK1/2 targeting as enhanced corrective approach. Combined pharmacologic JAK2/ERK1/2 inhibition with ruxolitinib and ERK inhibitors reduced proliferation of Jak2V617F cells and corrected erythrocytosis and splenomegaly of Jak2V617F MPN mice. Longer-term treatment was able to induce clone reductions. BM fibrosis was significantly decreased in MPLW515L-driven MPN to an extent not seen with JAK2 inhibitor monotherapy. Colony formation from JAK2V617F patients' CD34+ blood and BM was dose-dependently inhibited by combined JAK2/ERK1/2 inhibition in PV, ET, and MF subsets. Overall, we observed that dual targeting of JAK2 and ERK1/2 was able to enhance therapeutic efficacy suggesting a novel treatment approach for MPN.
  9. Nat Cancer. 2021 Jul;2 741-757
      RNA binding proteins (RBPs) are key arbiters of post-transcriptional regulation and are found to be found dysregulated in hematological malignancies. Here, we identify the RBP RBMX and its retrogene RBMXL1 to be required for murine and human myeloid leukemogenesis. RBMX/L1 are overexpressed in acute myeloid leukemia (AML) primary patients compared to healthy individuals, and RBMX/L1 loss delayed leukemia development. RBMX/L1 loss lead to significant changes in chromatin accessibility, as well as chromosomal breaks and gaps. We found that RBMX/L1 directly bind to mRNAs, affect transcription of multiple loci, including CBX5 (HP1α), and control the nascent transcription of the CBX5 locus. Forced CBX5 expression rescued the RBMX/L1 depletion effects on cell growth and apoptosis. Overall, we determine that RBMX/L1 control leukemia cell survival by regulating chromatin state through their downstream target CBX5. These findings identify a mechanism for RBPs directly promoting transcription and suggest RBMX/L1, as well as CBX5, as potential therapeutic targets in myeloid malignancies.
  10. Leukemia. 2021 Aug 31.
      Persistence of malignant clones is a major determinant of adverse outcome in patients with hematologic malignancies. Despite the fact that the majority of patients with acute myeloid leukemia (AML) achieve complete remission after chemotherapy, a large proportion of them relapse as a result of residual malignant cells. These persistent clones have a competitive advantage and can re-establish disease. Therefore, targeting strategies that specifically diminish cell competition of malignant cells while leaving normal cells unaffected are clearly warranted. Recently, our group identified YBX1 as a mediator of disease persistence in JAK2-mutated myeloproliferative neoplasms. The role of YBX1 in AML, however, remained so far elusive. Here, inactivation of YBX1 confirms its role as an essential driver of leukemia development and maintenance. We identify its ability to amplify the translation of oncogenic transcripts, including MYC, by recruitment to polysomal chains. Genetic inactivation of YBX1 disrupts this regulatory circuit and displaces oncogenic drivers from polysomes, with subsequent depletion of protein levels. As a consequence, leukemia cells show reduced proliferation and are out-competed in vitro and in vivo, while normal cells remain largely unaffected. Collectively, these data establish YBX1 as a specific dependency and therapeutic target in AML that is essential for oncogenic protein expression.
  11. J Hematol Oncol. 2021 Sep 03. 14(1): 137
      Quantification of measurable residual disease (MRD) provides critical prognostic information in acute myeloid leukemia (AML). A variety of platforms exist for MRD detection, varying in their sensitivity and applicability to individual patients. MRD detected by quantitative polymerase chain reaction, multiparameter flow cytometry, or next-generation sequencing has prognostic implications in various subsets of AML and at various times throughout treatment. While it is overwhelmingly evident that minute levels of remnant disease confer increased risk of relapse and shortened survival, the therapeutic implications of MRD remain less clear. The use of MRD as a guide to selecting the most optimal post-remission therapy, including hematopoietic stem cell transplant or maintenance therapy with hypomethylating agents, small molecule inhibitors, or immunotherapy is an area of active investigation. In addition, whether there are sufficient data to use MRD negativity as a surrogate endpoint in clinical trial development is controversial. In this review, we will critically examine the methods used to detect MRD, its role as a prognostic biomarker, MRD-directed therapeutics, and its potential role as a study endpoint.
    Keywords:  Acute myeloid leukemia; Measurable residual disease; Surrogate endpoint
  12. Cancer Immunol Immunother. 2021 Sep 03.
      Harnessing or monitoring immune cells is actually a major topic in pre-clinical and clinical studies in acute myeloid leukemia (AML). Mucosal-Associated Invariant T cells (MAIT) constitute one of the largest subset of innate-like, cytotoxic T cell subsets in humans. Despite some papers suggesting a role for MAIT cells in cancer, their specific involvement remains unclear, especially in myeloid malignancies. This prospective monocentric study included 216 patients with a newly diagnosed AML. Circulating MAIT cells were quantified by flow cytometry at diagnosis and during intensive chemotherapy. We observed that circulating MAIT cells show a specific decline in AML patients at diagnosis compared to healthy donors. Post-induction monitored patients presented with a drastic drop in MAIT cell numbers, with recovery after one month. We also found correlation between decrease in MAIT cells number and adverse cytogenetic profile. FLT3-ITD and IDH ½ mutations were associated with higher MAIT cell numbers. Patients with high level of activated MAIT cells are under-represented within patients with a favorable cytogenetic profile, and over-represented among patients with IDH1 mutations or bi-allelic CEBPA mutations. We show for the first time that circulating MAIT cells are affected in newly diagnosed AML patients, suggesting a link between MAIT cells and AML progression. Our work fosters new studies to deepen our knowledge about the role of MAIT cells in cancer.
    Keywords:  AML; Immune surveillance; Immunotherapy; MAIT; MR1
  13. Cancer Discov. 2021 Aug 30. pii: candisc.0032.2021. [Epub ahead of print]
      Ineffective hematopoiesis is a fundamental process leading to the pathogenesis of myelodysplastic syndromes (MDS). However, the pathobiological mediators of ineffective hematopoiesis in MDS remain unclear. Here, we demonstrated that overwhelming mitochondrial fragmentation in mutant hematopoietic stem cells and progenitors (HSC/Ps) triggers ineffective hematopoiesis in MDS. Mouse modeling of CBL exon-deletion with RUNX1 mutants, previously unreported co-mutations in MDS patients, recapitulated not only clinically relevant MDS phenotypes but also a distinct MDS-related gene signature. Mechanistically, dynamin-related protein 1 (DRP1)-dependent excessive mitochondrial fragmentation in HSC/Ps led to excessive ROS production, induced inflammatory signaling activation, and promoted subsequent dysplasia formation and impairment of granulopoiesis. Mitochondrial fragmentation was generally observed in patients with MDS. Pharmacological inhibition of DRP1 attenuated mitochondrial fragmentation and rescued ineffective hematopoiesis phenotypes in MDS mice. These findings provide mechanistic insights into ineffective hematopoiesis and indicate that dysregulated mitochondrial dynamics could be a therapeutic target for bone marrow failure in MDS.
  14. Cell Rep. 2021 Aug 31. pii: S2211-1247(21)01064-0. [Epub ahead of print]36(9): 109626
      Somatic mutations in spliceosome genes are found in ∼50% of patients with myelodysplastic syndromes (MDS), a myeloid malignancy associated with low blood counts. Expression of the mutant splicing factor U2AF1(S34F) alters hematopoiesis and mRNA splicing in mice. Our understanding of the functionally relevant alternatively spliced target genes that cause hematopoietic phenotypes in vivo remains incomplete. Here, we demonstrate that reduced expression of H2afy1.1, an alternatively spliced isoform of the histone H2A variant gene H2afy, is responsible for reduced B cells in U2AF1(S34F) mice. Deletion of H2afy or expression of U2AF1(S34F) reduces expression of Ebf1 (early B cell factor 1), a key transcription factor for B cell development, and mechanistically, H2AFY is enriched at the EBF1 promoter. Induced expression of H2AFY1.1 in U2AF1(S34F) cells rescues reduced EBF1 expression and B cells numbers in vivo. Collectively, our data implicate alternative splicing of H2AFY as a contributor to lymphopenia induced by U2AF1(S34F) in mice and MDS.
    Keywords:  B-lymphopoiesis; EBF1; H2AFY; U2AF1; U2AF1(S34F); alternative splicing; hematopoiesis; macroH2A1; myelodysplastic syndromes; spliceosome gene mutations
  15. Leukemia. 2021 Aug 30.
      Lysosomes, since their discovery, have been primarily known for degrading cellular macromolecules. However, in recent studies, they have begun to emerge as crucial regulators of cell homeostasis. They are at the crossroads of catabolic and anabolic pathways and are intricately involved in cellular trafficking, nutrient signaling, energy metabolism, and immune regulation. Their involvement in such essential cellular functions has renewed clinical interest in targeting the lysosome as a novel way to treat disease, particularly cancer. Acute myeloid leukemia (AML) is an aggressive blood cancer with a low survival probability, particularly in older patients. The genomic landscape of AML has been extensively characterized but few targeted therapies (with the exception of differentiation therapy) can achieve a long-term cure. Therefore, there is an unmet need for less intensive and more tolerable therapeutic interventions. In this review, we will give an overview on the myriad of functions performed by lysosomes and their importance in malignant disease. Furthermore, we will discuss their relevance in hematopoietic cells and different ways to potentially target them in AML.
  16. Blood Adv. 2021 Aug 31. pii: bloodadvances.2021004571. [Epub ahead of print]
      Current strategies to target RNA splicing mutant myeloid cancers proposes targeting the remaining splicing apparatus. This approach has only been modestly sensitizing and is also toxic to non-mutant bearing wild-type cells. To explore potentially exploitable genetic interactions with spliceosome mutations, we combined data mining and functional screening for synthetic lethal interactions with an Srsf2P95H/+ mutation. Analysis of mis-splicing events in a series of both human and murine SRSF2P95H mutant samples across multiple myeloid diseases (AML, MDS, CMML) was performed to identify conserved mis-splicing events. From this analysis, we identified that the cell cycle and DNA repair pathways were overrepresented within the conserved mis-spliced transcript sets. In parallel, to functionally define pathways essential for survival and proliferation of Srsf2P95H/+ cells, we performed a genome-wide CRISPR loss of function screen using Hoxb8 immortalized R26-CreERki/+ Srsf2P95H/+ and R26-CreERki/+ Srsf2+/+ cell lines. We assessed loss of sgRNA representation at three timepoints: immediately after Srsf2P95H/+ activation, and at one week and two weeks post Srsf2P95H/+ mutation. Pathway analysis demonstrated that the cell cycle and DNA damage response pathways were amongst the top synthetic lethal pathways with Srsf2P95H/+ mutation. Based on the loss of guide RNAs targeting Cdk6, we identified that Palbociclib, a CDK6 inhibitor, showed preferential sensitivity in Srsf2P95H/+ cell lines and in primary non-immortalized lin-cKIT+Sca-1+ cells compared to wild type controls. Our data strongly suggest that the cell cycle and DNA damage response pathways are required for Srsf2P95H/+ cell survival, and that Palbociclib could be an alternative therapeutic option for targeting SRSF2 mutant cancers.
  17. Pediatr Blood Cancer. 2021 Sep 02. e29313
      BACKGROUND: The optimal number of chemotherapy courses for low-risk (LR) pediatric acute myeloid leukemia (AML) is not known.OBJECTIVE: To compare outcomes for four (21.6 g/m2 cytarabine) versus five (45.6 g/m2 cytarabine) chemotherapy courses for LR-AML using data from Children's Oncology Group (COG) AAML0531 and AAML1031.
    METHODS: We compared relapse risk (RR), disease-free survival (DFS), and overall survival (OS), and the differential impact in LR subgroups for patients receiving four versus five chemotherapy courses. Cox (OS and DFS) and risk (RR) regressions were used to estimate hazard ratios (HR) to compare outcomes.
    RESULTS: A total of 923 LR-AML patients were included; 21% received five courses. Overall, LR-AML patients who received four courses had higher RR (40.9% vs. 31.4%; HR = 1.40, 95% confidence interval [CI]: 1.06-1.85), and worse DFS (56.0% vs. 67.0%; HR = 1.45, 95% CI: 1.10-1.91). There was a similar decrement in OS though it was not statistically significant (77.0% vs. 83.5%; HR = 1.45, 95% CI: 0.97-2.17). Stratified analyses revealed the detrimental effects of cytarabine dose de-escalation to be most pronounced in the LR-AML subgroup with uninformative cytogenetic/molecular features who were minimal residual disease (MRD) negative after the first induction course (EOI1). The absolute decrease in DFS with four courses for patients with favorable cytogenetic/molecular features and positive MRD was similar to that observed for patients with uninformative cytogenetic/molecular features and negative MRD at EOI1, though not statistically significant.
    CONCLUSIONS: Our results support de-escalation of cytarabine exposure through the elimination of a fifth chemotherapy course only for LR-AML patients who have both favorable cytogenetic/molecular features and negative MRD after the first induction cycle.
    Keywords:  chemotherapy; cytarabine; de-escalation; pediatric acute myeloid leukemia
  18. Exp Hematol. 2021 Aug 28. pii: S0301-472X(21)00289-7. [Epub ahead of print]
      Hematopoietic stem cells (HSCs) are immature blood cells that exhibit multi-lineage differentiation capacity. Homeostasis is critical for HSC potential and life-long hematopoiesis, and HSC homeostasis is tightly governed by both intrinsic molecular networks and microenvironmental signals. The evolutionarily conserved serine/threonine protein kinase B (PKB, also referred to as Akt) -mammalian target of rapamycin (mTOR) pathway is universal to nearly all multicellular organisms and plays an integral role in most cellular processes. Emerging evidence has revealed a central role of the Akt-mTOR network in HSC homeostasis, as it responses to multiple intracellular and extracellular signals and regulates various downstream targets, eventually affecting several cellular processes, including the cell cycle, mitochondrial metabolism, and protein synthesis. The dysregulated Akt-mTOR signaling greatly affects HSC self-renewal, maintenance, differentiation, survival, and autophagy, and aging, as well as transformation of HSCs to leukemia stem cells (LSCs). Here, we review recent works and provide an advanced understanding of how the Akt-mTOR network regulates HSC homeostasis, thus offering insights for future clinical applications.
    Keywords:  Akt-mTOR; Hematopoietic stem cells; Homeostasis; Leukemia stem cells
  19. Transplant Cell Ther. 2021 Aug 30. pii: S2666-6367(21)01171-4. [Epub ahead of print]
      BACKGROUND: Programmed death-1 (PD-1) is an integral component of acute myeloid leukemia (AML) immune evasion, chemotherapy resistance, and disease progression. PD-1 inhibitors are being investigated as treatment for AML in combination with hypomethylating agents and cytotoxic chemotherapy with encouraging findings.OBJECTIVE: Although allogeneic stem cell transplant (alloSCT) remains the most established curative treatment for relapsed and refractory AML patients in complete remission, there are limited data on the clinical outcomes and safety of immune checkpoint inhibitors (ICIs) prior to alloSCT in AML.
    STUDY DESIGN: We compared clinical outcomes of AML patients receiving high-dose cytarabine followed by pembrolizumab (n=8) in a phase II clinical trial (NCT02768792) prior to alloSCT versus a historical control group of AML patients who received alloSCT without prior ICI exposure (n=18). The nonparametric Jonckheere-Terpstra test was used to test for a difference in the ordered severity categories of aGVHD within 100 days of transplant. The time-to-event estimates for OS and relapse-free survival were calculated using the Kaplan-Meier method and compared using a log rank test.
    RESULTS: One-year survival was not significantly different between both treatment groups (67% versus 78%, p = 0.34). 100-day mortality was 0% in the pembrolizumab cohort versus 17% in control group, and there was no increase in grade III-IV acute graft-versus-host disease in patients treated with pembrolizumab prior to alloSCT. No chronic graft-versus-host disease was seen in patients treated with pembrolizumab prior to alloSCT and who received post-transplant cyclophosphamide as part of their conditioning regimen.
    CONCLUSION: These findings reinforce the safety and feasibility of ICI prior to alloSCT in AML. These results suggest post-transplant cyclophosphamide may abrogate GVHD risk and severity in patients who receive ICI prior to alloSCT in AML.
    Keywords:  ‘AML’; ‘BMT’; ‘GVHD’; ‘HSCT’; ‘Immunotherapy’
  20. Leuk Lymphoma. 2021 Sep 03. 1-8
      The role of allogeneic hematopoietic cell transplant (allo-HCT) as consolidation after initial venetoclax therapy and the efficacy of venetoclax salvage therapy for relapse after allo-HCT in patients with acute myeloid leukemia (AML) are unclear. We conducted a retrospective study of patients with AML or myelodysplastic syndrome (MDS) who received venetoclax either before or after allo-HCT at Memorial Sloan Kettering Cancer Center and Yale University from 11 August 2016 to 16 November 2020. Among 39 heavily pretreated patients who received venetoclax before allo-HCT, median OS from allo-HCT was not reached after a median follow up of 12.5 months resulting in a 12-month OS estimate of 79.0%. In 37 patients who had received venetoclax-based combinations as salvage therapy after allo-HCT, the overall response rate was 32% with a median OS of 4.7 months (12-month OS estimate: 43.4%). Four patients underwent a second allo-HCT following venetoclax-based salvage therapy suggesting it as a potential salvage treatment option.
    Keywords:  AML; Acute myeloid leukemia; MDS; transplant; venetoclax
  21. Ann Hematol. 2021 Sep 03.
      We evaluated the survival patterns for acute myeloid leukemia (AML) patients registered in the Osaka Cancer Registry from 1975 to 2017. During this period, 9706 patients were diagnosed with AML, with a median age of 60 years (range, 0-100). Patients were grouped by age (≤ 20, 21-40, 41-60, 61-70, and ≥ 71) and the year of their diagnosis (1975-1989, 1990-2001, 2002-2010, and 2011-2017). The overall survival (OS) rates of patients of ≤ 60 years of age improved significantly from the period 1975-1989 up to 1990-2001. However, there was a stagnation from 2002-2010 to 2011-2017. In terms of non-acute promyelocytic leukemia patients of > 60 years of age, the improvement of OS was limited during a very long period. In conclusion, the clinical outcome of patients with AML dramatically improved from 1975 to 2001. However, our dataset revealed stagnation in the improvement since 2002. Novel treatment options are needed to further improve the survival of elderly patients.
    Keywords:  Acute myeloid leukemia; Allogeneic hematopoietic cell transplantation; Elderly
  22. Blood Adv. 2021 Sep 14. 5(17): 3266-3278
      Peripheral blood cytopenias may precede the development of hematological malignancies and frequently pose clinical challenges in the older population. The natural course of (mild) cytopenias during aging and their association with hematological disorders in community-dwelling individuals are not well studied. Within the population-based Lifelines cohort (n = 167729), we studied changes in peripheral blood counts, occurrence of cytopenias, and associated hematological outcomes in the context of aging. Development of hematological malignancies and (cause-specific) mortality were evaluated by linkage to nationwide registries. Anemia and thrombocytopenia emerged with older age, in line with a general age-related decline in these blood counts. For neutropenia, no increase in prevalence with older age was observed. Using standard reference limits to define cytopenias, anemia (hazard ratio [HR], 1.84; 95% confidence interval [CI], 1.59-2.12), thrombocytopenia (HR, 1.58; 95% CI, 1.32-1.89), and, especially the concomitant presence of anemia and thrombocytopenia (HR, 4.75; 95% CI, 2.98-7.55) were associated with inferior overall survival. Only a minor proportion of deaths was explained by diagnosed hematological malignancies, with the majority attributable to other causes. Neutropenia, either isolated (HR, 0.88; 95% CI, 0.73-1.06) or combined with another cytopenia, did not affect overall survival. For individuals aged ≥60 years, 5-year cumulative incidence of hematological malignancies was 0.60% (95% CI, 0.50-0.70), with higher incidences among those with anemia (P < .001) or thrombocytopenia (P < .001) but not neutropenia (P = .201). Highest cumulative incidences of diagnoses and mortality from hematological malignancies were observed in individuals with >1 cytopenia. We conclude that anemia and thrombocytopenia, but not neutropenia, are associated with inferior overall survival of community-dwelling individuals. Hematological malignancies develop in a small fraction of these cases.
  23. Onco Targets Ther. 2021 ;14 4509-4521
      Myelofibrosis (MF) is a clonal hematologic malignancy characterized by bone marrow fibrosis, extramedullary hematopoiesis, splenomegaly, and constitutional symptoms with a propensity towards leukemic transformation. Constitutive activation of the JAK/STAT pathway is a well-described pathogenic feature of MF. Allogeneic stem cell transplant is the only curative therapy, but due to high morbidity and mortality this option is not available for most patients. There are two approved targeted therapy options for MF, ruxolitinib and fedratinib. In this review, we discuss the clinical utility of fedratinib in the myelofibrosis treatment paradigm. Fedratinib has shown impressive pre-clinical and clinical efficacy in patients with untreated MF as well as in those with ruxolitinib intolerance and those with relapsed/refractory MF. Here, we review the pre-clinical and clinical trials that led to the approval of fedratinib, and the ongoing late-phase trials. We highlight several areas regarding the clinical utility of fedratinib that remain unanswered. We discuss the limitations of fedratinib and address areas that are understudied and require further clinical evaluation and research. The approval of fedratinib has provided a significant expansion to the very limited treatment armamentarium available to patients with MF.
    Keywords:  JAK inhibitor; fedratinib; myelofibrosis; targeted therapy
  24. Cell Chem Biol. 2021 Aug 30. pii: S2451-9456(21)00393-7. [Epub ahead of print]
      Nuclear receptor binding SET domain protein 3 (NSD3), a gene located within the 8p11-p12 amplicon frequently detected in human cancers, encodes a chromatin modulator and an attractive onco-target. However, agents that effectively suppress NSD3-mediated oncogenic actions are currently lacking. We report the NSD3-targeting proteolysis targeting chimera (PROTAC), MS9715, which achieves effective and specific targeting of NSD3 and associated cMyc node in tumor cells. MS9715 is designed by linking BI-9321, a NSD3 antagonist, which binds NSD3's PWWP1 domain, with an E3 ligase VHL ligand. Importantly, MS9715, but not BI-9321, effectively suppresses growth of NSD3-dependent hematological cancer cells. Transcriptomic profiling demonstrates that MS9715, but not BI-9321, effectively suppresses NSD3-and cMyc-associated gene expression programs, resembling effects of the CRISPR-Cas9-mediated knockout of NSD3. Collectively, these results suggest that pharmacological degradation of NSD3 as an attractive therapeutic strategy, which co-suppresses NSD3- and cMyc-related oncogenic nodes, is superior to blocking the PWWP1 domain of NSD3.
    Keywords:  NSD3; PROTAC; cMyc; cancer; chromatin; degrader; epigenetics; histone; ubiquitylation
  25. Nat Commun. 2021 Sep 02. 12(1): 5241
      Individual induced pluripotent stem cells (iPSCs) show considerable phenotypic heterogeneity, but the reasons for this are not fully understood. Comprehensively analysing the mitochondrial genome (mtDNA) in 146 iPSC and fibroblast lines from 151 donors, we show that most age-related fibroblast mtDNA mutations are lost during reprogramming. However, iPSC-specific mutations are seen in 76.6% (108/141) of iPSC lines at a mutation rate of 8.62 × 10-5/base pair. The mutations observed in iPSC lines affect a higher proportion of mtDNA molecules, favouring non-synonymous protein-coding and tRNA variants, including known disease-causing mutations. Analysing 11,538 single cells shows stable heteroplasmy in sub-clones derived from the original donor during differentiation, with mtDNA variants influencing the expression of key genes involved in mitochondrial metabolism and epidermal cell differentiation. Thus, the dynamic mtDNA landscape contributes to the heterogeneity of human iPSCs and should be considered when using reprogrammed cells experimentally or as a therapy.
  26. Blood Adv. 2021 Sep 14. 5(17): 3373-3376
      The molecular causes of myeloproliferative neoplasms (MPNs) have not yet been fully elucidated. Approximately 7% to 8% of the patients carry predisposing genetic germline variants that lead to driver mutations, which enhance JAK-STAT signaling. To identify additional predisposing genetic germline variants, we performed whole-exome sequencing in 5 families, each with parent-child or sibling pairs affected by MPNs and carrying the somatic JAK2 V617F mutation. In 4 families, we detected rare germline variants in known tumor predisposition genes of the DNA repair pathway, including the highly penetrant BRCA1 and BRCA2 genes. The identification of an underlying hereditary tumor predisposition is of major relevance for the individual patients as well as for their families in the context of therapeutic options and preventive care. Two patients with essential thrombocythemia or polycythemia vera experienced progression to acute myeloid leukemia, which may suggest a high risk of leukemic transformation in these familial MPNs. Our study demonstrates the relevance of genetic germline diagnostics in elucidating the causes of MPNs and suggests novel therapeutic options (eg, PARP inhibitors) in MPNs. Furthermore, we uncover a broader tumor spectrum upon the detection of a germline mutation in genes of the DNA repair pathway.
  27. Cancer Discov. 2019 Oct;9(10): 1336
      SF3B1 mutations, common in myelodysplastic syndromes, cause SUGP1-mediated splicing defects.
  28. EMBO J. 2021 Aug 30. e108863
      Autophagy is a core molecular pathway for the preservation of cellular and organismal homeostasis. Pharmacological and genetic interventions impairing autophagy responses promote or aggravate disease in a plethora of experimental models. Consistently, mutations in autophagy-related processes cause severe human pathologies. Here, we review and discuss preclinical data linking autophagy dysfunction to the pathogenesis of major human disorders including cancer as well as cardiovascular, neurodegenerative, metabolic, pulmonary, renal, infectious, musculoskeletal, and ocular disorders.
    Keywords:  aging; cancer; inflammation; metabolic syndromes; neurodegeneration
  29. Cancer Discov. 2019 Nov;9(11): 1481
      Asciminib with ponatinib was more effective than either alone in chronic myeloid leukemia (CML).
  30. Blood Adv. 2021 Sep 01. pii: bloodadvances.2020003534. [Epub ahead of print]
      Treating refractory pediatric acute lymphoblastic leukemia (ALL) remains a challenge despite impressive remission rates (>90%) achieved in the last decade. The use of innovative immunotherapeutic approaches, such as anti-CD19 chimeric antigen receptor T cells does not ensure durable remissions, as cells with leukemia propagating ability (LPC) that lack expression of CD19 can cause relapse, signifying the need to identify new markers of ALL. Here we investigated expression of CD58, CD97 and CD200, previously shown to be overexpressed in B cell precursor (BCP) ALL, in CD34+/CD19+, CD34+/CD19-, CD34-/CD19+ and CD34-/CD19- LPC to assess their potential as therapeutic targets. Whole genome microarray and flow cytometric analyses showed significant overexpression of these molecules compared to normal controls. CD58 and CD97 were mainly co-expressed with CD19 and were not prerequisite for leukemia engraftment in immune deficient mice. In contrast, expression of CD200 was essential for engraftment and serial transplantation of cells in measurable residual disease (MRD) low risk cases. Moreover, these CD200+ LPC could be targeted using the monoclonal antibody, TTI-CD200, in vitro and in vivo. Treating mice with established disease significantly reduced disease burden and extended survival. These findings demonstrate that CD200 could be an attractive target for treating low risk ALL, with minimal off tumour effects that beset current immunotherapeutic approaches.
  31. Blood Adv. 2021 Aug 31. pii: bloodadvances.2020003754. [Epub ahead of print]
      Juvenile myelomonocytic leukemia (JMML) is initiated in early childhood by somatic mutations that activate Ras signaling. While some patients have only a single identifiable oncogenic mutation, others have one or more additional alterations. Such secondary mutations, as a group, are associated with an increased risk of relapse after hematopoietic stem cell transplantation, or transformation to acute myeloid leukemia. These clinical observations suggest a cooperative effect between initiating and secondary mutations. However, the roles of specific genes in the prognosis or clinical presentation of JMML have not been described. In this study, we investigate the impact of secondary SH2B3 mutations in JMML. We find that patients with SH2B3 mutations have adverse outcomes, as well as higher white blood cell counts and hemoglobin F levels in the peripheral blood. We further demonstrate this interaction in genetically engineered mice. Deletion of Sh2b3 cooperates with conditional Nf1 deletion in a dose-dependent fashion. These studies illustrate that haploinsufficiency for Sh2b3 contributes to the severity of myeloproliferative disease and provide an experimental system for testing treatments for a high-risk cohort of JMML patients.
  32. Cell Stem Cell. 2021 Aug 27. pii: S1934-5909(21)00341-6. [Epub ahead of print]
      DDX41 mutations are the most common germline alterations in adult myelodysplastic syndromes (MDSs). The majority of affected individuals harbor germline monoallelic frameshift DDX41 mutations and subsequently acquire somatic mutations in their other DDX41 allele, typically missense R525H. Hematopoietic progenitor cells (HPCs) with biallelic frameshift and R525H mutations undergo cell cycle arrest and apoptosis, causing bone marrow failure in mice. Mechanistically, DDX41 is essential for small nucleolar RNA (snoRNA) processing, ribosome assembly, and protein synthesis. Although monoallelic DDX41 mutations do not affect hematopoiesis in young mice, a subset of aged mice develops features of MDS. Biallelic mutations in DDX41 are observed at a low frequency in non-dominant hematopoietic stem cell clones in bone marrow (BM) from individuals with MDS. Mice chimeric for monoallelic DDX41 mutant BM cells and a minor population of biallelic mutant BM cells develop hematopoietic defects at a younger age, suggesting that biallelic DDX41 mutant cells are disease modifying in the context of monoallelic DDX41 mutant BM.
    Keywords:  BM failure; DDX41; myelodysplastic syndrome; protein synthesis; ribosome biogenesis; snoRNA
  33. Blood Adv. 2021 Sep 02. pii: bloodadvances.2021005148. [Epub ahead of print]
      Data regarding racial and ethnic enrollment diversity for acute myeloid (AML) and lymphoid leukemia (ALL) clinical trials in the United States (US) are limited, and little is known about the effect of federal reporting requirements instituted in the late 2000s. We examined demographic data reporting and enrollment diversity for US ALL and AML trials from 2002-2017 as well as changes in reporting and diversity after reporting requirements were instituted. Of 223 AML and 97 ALL trials with results, 68 (30.5%) and 51 (52.6%) reported enrollment by both race and ethnicity. Among trials that reported race and ethnicity (AML N=6,554; ALL N=4,149), non-Hispanic (NH)-Black, NH-Native American, NH-Asian, and Hispanic patients had significantly lower enrollment compared to NH-white patients after adjusting for race-ethnic disease incidence (AML odds: 0.68, 0.31, 0.75, and 0.83; ALL: 0.74, 0.27, 0.67, and 0.64; all p≤0.01). The proportion of trials reporting race increased significantly after the reporting requirements (44.2 to 60.2%; p=0.02), but race-ethnicity reporting did not (34.8 to 38.6%; p=0.57). Reporting proportions by number of patients enrolled increased significantly after the reporting requirements (race: 51.7 to 72.7%, race-ethnicity: 39.5 to 45.4%; both p<0.001), and relative enrollment of NH-Black and Hispanic patients decreased (AML odds: 0.79 and 0.77; ALL: 0.35 and 0.25; both p≤0.01). These data suggest that demographic enrollment reporting for acute leukemia trials is suboptimal, changes in diversity after the reporting requirements may be due to additional enrollment disparities that were previously unreported, and enrollment diversification strategies specific to acute leukemia care delivery are needed.
  34. Blood Adv. 2021 Sep 14. 5(17): 3362-3372
      The use of umbilical cord blood transplant has been substantially limited by the finite number of hematopoietic stem and progenitor cells in a single umbilical cord blood unit. Small molecules that not only quantitatively but also qualitatively stimulate enhancement of hematopoietic stem cell (HSC) self-renewal ex vivo should facilitate the clinical use of HSC transplantation and gene therapy. Recent evidence has suggested that the cyclin-dependent kinase inhibitor, p18INK4C (p18), is a critical regulator of mice HSC self-renewal. The role of p18 in human HSCs and the effect of p18 inhibitor on human HSC expansion ex vivo need further studies. Here we report that knockdown of p18 allowed for an increase in long-term colony-forming cells in vitro. We then identified an optimized small molecule inhibitor of p18, 005A, to induce ex vivo expansion of HSCs that was capable of reconstituting human hematopoiesis for at least 4 months in immunocompromised mice, and hence, similarly reconstituted secondary recipients for at least 4 more months, indicating that cells exposed to 005A were still competent in secondary recipients. Mechanistic studies showed that 005A might delay cell division and activate both the Notch signaling pathway and expression of transcription factor HoxB4, leading to enhancement of the self-renewal of long-term engrafting HSCs and the pool of progenitor cells. Taken together, these observations support a role for p18 in human HSC maintenance and that the p18 inhibitor 005A can enhance the self-renewal of long-term HSCs.
  35. Blood Adv. 2021 Sep 14. 5(17): 3344-3353
      Since the introduction of imatinib, the management of chronic myeloid leukemia (CML) has changed considerably. Tyrosine kinase inhibitors (TKIs) are the mainstay of CML treatment; however, the high financial burden of TKIs can be problematic for both the patients and health care systems. After the emergence of generics, reimbursement policies of many countries have changed, and generics offered an alternative treatment option for CML patients. There are many papers published on the use of generics in CML patients with conflicting results regarding both efficacy and safety. In this paper, we systematically reviewed the current literature on generic imatinib use in CML, and 36 papers were evaluated. Both in vitro and in vivo studies of generic imatinib showed comparable results with branded imatinib in terms of bioequivalence and bioavailability. In most studies, generics were comparable with the original molecule in terms of efficacy and safety, both in newly diagnosed patients and after switching from Gleevec. Some generic studies showed contradictory findings regarding efficacy and toxicity, and these differences can be attributed to some factors including the use of different generics in different countries. Both in hypothetical models and in real life, introduction of generic imatinib caused significant reduction in health care costs. In conclusion, generics are not inferior to original imatinib in terms of efficacy with an acceptable toxicity profile. Notwithstanding the generally favorable efficacy and safety of generics worldwide to date, we most probably still need more time to draw firmer conclusions on the longer-term outcomes of generics.
  36. Leukemia. 2021 Sep 03.
      Polycythemia vera (PV) is a relatively indolent myeloid neoplasm with median survival that exceeds 35 years in young patients, but its natural history might be interrupted by thrombotic, fibrotic, or leukemic events, with respective 20-year rates of 26%, 16%, and 4%. Current treatment strategies in PV have not been shown to prolong survival or lessen the risk of leukemic or fibrotic progression and instead are directed at preventing thrombotic complications. In the latter regard, two risk categories are considered: high (age >60 years or thrombosis history) and low (absence of both risk factors). All patients require phlebotomy to keep hematocrit below 45% and once-daily low-dose aspirin, in the absence of contraindications. Cytoreductive therapy is recommended for high-risk or symptomatic low-risk disease; our first-line drug of choice in this regard is hydroxyurea but we consider pegylated interferon as an alternative in certain situations, including in young women of reproductive age, in patients manifesting intolerance or resistance to hydroxyurea therapy, and in situations where treatment is indicated for curbing phlebotomy requirement rather than preventing thrombosis. Additional treatment options include busulfan and ruxolitinib; the former is preferred in older patients and the latter in the presence of symptoms reminiscent of post-PV myelofibrosis or protracted pruritus. Our drug choices reflect our appreciation for long-term track record of safety, evidence for reduction of thrombosis risk, and broader suppression of myeloproliferation. Controlled studies are needed to clarify the added value of twice- vs once-daily aspirin dosing and direct oral anticoagulants. In this invited review, we discuss our current approach to diagnosis, prognostication, and treatment of PV in general, as well as during specific situations, including pregnancy and splanchnic vein thrombosis.
  37. Nat Genet. 2021 Sep 02.
    Urmo Võsa, Annique Claringbould, Harm-Jan Westra, Marc Jan Bonder, Patrick Deelen, Biao Zeng, Holger Kirsten, Ashis Saha, Roman Kreuzhuber, Seyhan Yazar, Harm Brugge, Roy Oelen, Dylan H de Vries, Monique G P van der Wijst, Silva Kasela, Natalia Pervjakova, Isabel Alves, Marie-Julie Favé, Mawussé Agbessi, Mark W Christiansen, Rick Jansen, Ilkka Seppälä, Lin Tong, Alexander Teumer, Katharina Schramm, Gibran Hemani, Joost Verlouw, Hanieh Yaghootkar, Reyhan Sönmez Flitman, Andrew Brown, Viktorija Kukushkina, Anette Kalnapenkis, Sina Rüeger, Eleonora Porcu, Jaanika Kronberg, Johannes Kettunen, Bernett Lee, Futao Zhang, Ting Qi, Jose Alquicira Hernandez, Wibowo Arindrarto, Frank Beutner, , , Julia Dmitrieva, Mahmoud Elansary, Benjamin P Fairfax, Michel Georges, Bastiaan T Heijmans, Alex W Hewitt, Mika Kähönen, Yungil Kim, Julian C Knight, Peter Kovacs, Knut Krohn, Shuang Li, Markus Loeffler, Urko M Marigorta, Hailang Mei, Yukihide Momozawa, Martina Müller-Nurasyid, Matthias Nauck, Michel G Nivard, Brenda W J H Penninx, Jonathan K Pritchard, Olli T Raitakari, Olaf Rotzschke, Eline P Slagboom, Coen D A Stehouwer, Michael Stumvoll, Patrick Sullivan, Peter A C 't Hoen, Joachim Thiery, Anke Tönjes, Jenny van Dongen, Maarten van Iterson, Jan H Veldink, Uwe Völker, Robert Warmerdam, Cisca Wijmenga, Morris Swertz, Anand Andiappan, Grant W Montgomery, Samuli Ripatti, Markus Perola, Zoltan Kutalik, Emmanouil Dermitzakis, Sven Bergmann, Timothy Frayling, Joyce van Meurs, Holger Prokisch, Habibul Ahsan, Brandon L Pierce, Terho Lehtimäki, Dorret I Boomsma, Bruce M Psaty, Sina A Gharib, Philip Awadalla, Lili Milani, Willem H Ouwehand, Kate Downes, Oliver Stegle, Alexis Battle, Peter M Visscher, Jian Yang, Markus Scholz, Joseph Powell, Greg Gibson, Tõnu Esko, Lude Franke.
      Trait-associated genetic variants affect complex phenotypes primarily via regulatory mechanisms on the transcriptome. To investigate the genetics of gene expression, we performed cis- and trans-expression quantitative trait locus (eQTL) analyses using blood-derived expression from 31,684 individuals through the eQTLGen Consortium. We detected cis-eQTL for 88% of genes, and these were replicable in numerous tissues. Distal trans-eQTL (detected for 37% of 10,317 trait-associated variants tested) showed lower replication rates, partially due to low replication power and confounding by cell type composition. However, replication analyses in single-cell RNA-seq data prioritized intracellular trans-eQTL. Trans-eQTL exerted their effects via several mechanisms, primarily through regulation by transcription factors. Expression of 13% of the genes correlated with polygenic scores for 1,263 phenotypes, pinpointing potential drivers for those traits. In summary, this work represents a large eQTL resource, and its results serve as a starting point for in-depth interpretation of complex phenotypes.
  38. Blood. 2021 Sep 02. 138(9): 790-805
      Therapy-related myeloid neoplasms (t-MNs) are high-risk late effects with poorly understood pathogenesis in cancer survivors. It has been postulated that, in some cases, hematopoietic stem and progenitor cells (HSPCs) harboring mutations are selected for by cytotoxic exposures and transform. Here, we evaluate this model in the context of deficiency of CUX1, a transcription factor encoded on chromosome 7q and deleted in half of t-MN cases. We report that CUX1 has a critical early role in the DNA repair process in HSPCs. Mechanistically, CUX1 recruits the histone methyltransferase EHMT2 to DNA breaks to promote downstream H3K9 and H3K27 methylation, phosphorylated ATM retention, subsequent γH2AX focus formation and propagation, and, ultimately, 53BP1 recruitment. Despite significant unrepaired DNA damage sustained in CUX1-deficient murine HSPCs after cytotoxic exposures, they continue to proliferate and expand, mimicking clonal hematopoiesis in patients postchemotherapy. As a consequence, preexisting CUX1 deficiency predisposes mice to highly penetrant and rapidly fatal therapy-related erythroleukemias. These findings establish the importance of epigenetic regulation of HSPC DNA repair and position CUX1 as a gatekeeper in myeloid transformation.
  39. Blood Adv. 2021 Aug 31. pii: bloodadvances.2021004658. [Epub ahead of print]
      Ribosome dysfunction is implicated in multiple abnormal developmental and disease states in humans. Heterozygous germline mutations in genes encoding ribosomal proteins (RPs) are found in the majority of individuals with Diamond Blackfan anemia (DBA) while somatic mutations have been implicated in a variety of cancers and other disorders. Ribosomal protein-deficient animal models show variable phenotypes and penetrance, similar to human DBA patients. Here we characterized a novel ENU mouse mutant (Skax23m1Jus) with growth and skeletal defects, cardiac malformations and increased mortality. Following genetic mapping and whole exome sequencing, we identified an intronic Rpl5 mutation, which segregated with all affected mice. This mutation was associated with decreased ribosome generation, consistent with Rpl5 haploinsufficiency. Rpl5Skax23-Jus/+ mutant animals had a profound delay in erythroid maturation and increased mortality at embryonic day E12.5, which improved by E14.5. Surviving mutant animals had a macrocytic anemia at birth as well as evidence of ventricular septal defect (VSD). Surviving adult and aged mice exhibited no hematopoietic defect or VSD. We propose that this novel Rpl5Skax23-Jus mutant mouse will be useful to study the factors influencing the variable penetrance that is observed in DBA.
  40. Blood Adv. 2021 Aug 30. pii: bloodadvances.2021004462. [Epub ahead of print]
      Haploidentical hematopoietic stem cell transplantation (haplo HSCT) has emerged as an important treatment modality. Most reports comparing haplo HSCT with post-transplant cyclophosphamide (PTCy) and other donor sources have focused on outcomes in older adults treated with reduced intensity conditioning. Therefore, in the current study, we evaluated outcomes in patients with hematological malignancy treated with myeloablative conditioning prior to haplo (n=375) or umbilical cord blood (UCB, n=333) HSCT. All haplo recipients received a 4 of 8 HLA matched graft while recipients of UCB were matched at 6-8/8 (n=145) or ≤5/8 (n=188) HLA antigens. Recipients of 6-8/8 UCB transplants were younger (14 years vs. 21 and 29 years) and more likely to have lower co-morbidity scores compared to recipients of ≤5/8 UCB and haplo HSCT (81% vs. 69% and 63%, respectively). UCB recipients were more likely to have acute lymphoblastic leukemia and transplanted in second complete remission (CR) whereas haplo HSCT recipients were more likely to have acute myeloid leukemia in first CR. Other characteristics, including cytogenetic risk were similar. Survival at 3 years was similar for the donor sources (66% haplo and 61% after ≤5/8 and 58% after 6-8/8 UCB). Notably, relapse at 3 years was lower in recipients of ≤5/8 UCB (21%, p=0.03) compared to haplo (36%) and 6-8/8 UCB (30%). However, non-relapse mortality was higher in ≤5/8 UCB (21%) compared to other groups (p<0.0001). These data suggest that haplo HSCT with PTCy after myeloablative conditioning provides an overall survival outcome comparable to that after UCB regardless HLA match group.