bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2022‒05‒29
twenty-six papers selected by
Paolo Gallipoli
Barts Cancer Institute, Queen Mary University of London

  1. Nat Med. 2022 May 26.
      The treatment landscape of acute myeloid leukemia (AML) is evolving, with promising therapies entering clinical translation, yet patient responses remain heterogeneous, and biomarkers for tailoring treatment are lacking. To understand how disease heterogeneity links with therapy response, we determined the leukemia cell hierarchy makeup from bulk transcriptomes of more than 1,000 patients through deconvolution using single-cell reference profiles of leukemia stem, progenitor and mature cell types. Leukemia hierarchy composition was associated with functional, genomic and clinical properties and converged into four overall classes, spanning Primitive, Mature, GMP and Intermediate. Critically, variation in hierarchy composition along the Primitive versus GMP or Primitive versus Mature axes were associated with response to chemotherapy or drug sensitivity profiles of targeted therapies, respectively. A seven-gene biomarker derived from the Primitive versus Mature axis was associated with response to 105 investigational drugs. Cellular hierarchy composition constitutes a novel framework for understanding disease biology and advancing precision medicine in AML.
  2. Blood Adv. 2022 May 23. pii: bloodadvances.2022007168. [Epub ahead of print]
      Allogeneic hematopoietic stem cell transplantation (HSCT) offers the best chance for relapse-free survival to most acute myeloid leukemia (AML) patients. It might be performed in complete remission or delayed until after first relapse due to relevant treatment-related morbidity and mortality. The measurable residual disease (MRD) status at HSCT adds refined prognostic information to the assigned European LeukemiaNet (ELN) 2017 genetic risk at diagnosis. We analyzed 580 AML patients receiving allogeneic HSCT in either first (79%) or second (21%) remission. Although - due to common treatment strategies - some adverse risk characteristics, such as monosomal or complex karyotypes were less frequent in patients transplanted in second remission, they had worse outcomes compared to patients transplanted in first remission. The MRD status at HSCT was an independent prognostic factor irrespective of the number of remission at HSCT. Noteworthy, MRDpos patients transplanted in first remission and MRDneg patients transplanted in second remission had similar outcomes. In the clinically highly relevant group of ELN2017 intermediate risk individuals, the MRD status provided the highest prognostic value with very dismal outcomes of patients transplanted in MRDpos second remission. The adverse outcomes of MRDpos patients and individuals transplanted in second remission should be considered when planning consolidation treatment, to avert an allogeneic HSCT in MRDpos second remission when possible.
  3. Leukemia. 2022 May 27.
      Gain-of-function kinase mutations are common in AML and usually portend an inferior prognosis. We reported a novel mechanism whereby kinase mutants induced intracellular alkalization characteristic in oncogenesis. Thirteen kinases were found to activate sodium/hydrogen exchanger (NHE1) in normal hematopoietic progenitors, of which FLT3-ITD, KRASG12D, and BTK phosphorylated NHE1 maintained alkaline intracellular pH (pHi) and supported survival of AML cells. Primary AML samples with kinase mutations also showed increased NHE1 phosphorylation and evidence of NHE1 addiction. Amiloride enhanced anti-leukemic effects and intracellular distribution of kinase inhibitors and chemotherapy. Co-inhibition of NHE1 and kinase synergistically acidified pHi in leukemia and inhibited its growth in vivo. Plasma from patients taking amiloride for diuresis reduced pHi of leukemia and enhanced cytotoxic effects of kinase inhibitors and chemotherapy in vitro. NHE1-mediated intracellular alkalization played a key pathogenetic role in transmitting the proliferative signal from mutated-kinase and could be exploited for therapeutic intervention in AML.
  4. Leukemia. 2022 May 26.
      Eradicating leukemia requires a deep understanding of the interaction between leukemic cells and their protective microenvironment. The CXCL12/CXCR4 axis has been postulated as a critical pathway dictating leukemia stem cell (LSC) chemoresistance in AML due to its role in controlling cellular egress from the marrow. Nevertheless, the cellular source of CXCL12 in the acute myeloid leukemia (AML) microenvironment and the mechanism by which CXCL12 exerts its protective role in vivo remain unresolved. Here, we show that CXCL12 produced by Prx1+ mesenchymal cells but not by mature osteolineage cells provide the necessary cues for the maintenance of LSCs in the marrow of an MLL::AF9-induced AML model. Prx1+ cells promote survival of LSCs by modulating energy metabolism and the REDOX balance in LSCs. Deletion of Cxcl12 leads to the accumulation of reactive oxygen species and DNA damage in LSCs, impairing their ability to perpetuate leukemia in transplantation experiments, a defect that can be attenuated by antioxidant therapy. Importantly, our data suggest that this phenomenon appears to be conserved in human patients. Hence, we have identified Prx1+ mesenchymal cells as an integral part of the complex niche-AML metabolic intertwining, pointing towards CXCL12/CXCR4 as a target to eradicate parenchymal LSCs in AML.
  5. Int J Mol Sci. 2022 May 16. pii: 5555. [Epub ahead of print]23(10):
      Acute myeloid leukemia (AML) is a hematological malignancy with a high risk of relapse. This issue is associated with the development of mechanisms leading to drug resistance that are not yet fully understood. In this context, we previously showed the clinical significance of the ATP binding cassette subfamily B-member 1 (ABCB1) in AML patients, namely its association with stemness markers and an overall worth prognosis. Calcium signaling dysregulations affect numerous cellular functions and are associated with the development of the hallmarks of cancer. However, in AML, calcium-dependent signaling pathways remain poorly investigated. With this study, we show the involvement of the ORAI1 calcium channel in store-operated calcium entry (SOCE), the main calcium entry pathway in non-excitable cells, in two representative human AML cell lines (KG1 and U937) and in primary cells isolated from patients. Moreover, our data suggest that in these models, SOCE varies according to the differentiation status, ABCB1 activity level and leukemic stem cell (LSC) proportion. Finally, we present evidence that ORAI1 expression and SOCE amplitude are modulated during the establishment of an apoptosis resistance phenotype elicited by the chemotherapeutic drug Ara-C. Our results therefore suggest ORAI1/SOCE as potential markers of AML progression and drug resistance apparition.
    Keywords:  ABCB1; AML; Ara-C; NFAT; ORAI1; SOCE; calcium; leukemic stem cells
  6. Leukemia. 2022 May 27.
      Myeloid ecotropic virus insertion site 1 (MEIS1) is essential for normal hematopoiesis and is a critical factor in the pathogenesis of a large subset of acute myeloid leukemia (AML). Despite the clinical relevance of MEIS1, its regulation is largely unknown. To understand the transcriptional regulatory mechanisms contributing to human MEIS1 expression, we created a knock-in green florescent protein (GFP) reporter system at the endogenous MEIS1 locus in a human AML cell line. Using this model, we have delineated and dissected a critical enhancer region of the MEIS1 locus for transcription factor (TF) binding through in silico prediction in combination with oligo pull-down, mass-spectrometry and knockout analysis leading to the identification of FLI1, an E-twenty-six (ETS) transcription factor, as an important regulator of MEIS1 transcription. We further show direct binding of FLI1 to the MEIS1 locus in human AML cell lines as well as enrichment of histone acetylation in MEIS1-high healthy and leukemic cells. We also observe a positive correlation between high FLI1 transcript levels and worse overall survival in AML patients. Our study expands the role of ETS factors in AML and our model constitutes a feasible tool for a more detailed understanding of transcriptional regulatory elements and their interactome.
  7. Leuk Res. 2022 May 11. pii: S0145-2126(22)00084-4. [Epub ahead of print]118 106858
      Leukemic transformation (LT) is the main cause of death for patients with myeloproliferative neoplasms (MPNs). To study genetic changes associated with the LT, we performed targeted sequencing in 26 MPN patients including 21 with paired samples. We observed that, besides three driver genes, IDH2 (19%) and ASXL1 (14%) were also frequently mutated at MPN diagnosis. Although variant allele frequencies (VAFs) of mutations in DNA methylation and spliceosome did not expand during LT, they were enriched in patients with LT (the LT group). At follow-up, we also observed acquisition of mutations, mostly in the LT group. When considering dynamics of VAF from diagnosis to follow-up, VAFs in the LT group expanded (median VAF, 36.7-43.7%, p = 0.045). In contrast, mutations in patients with no clinical progression was stable (median VAF, 36.3-35.7%, p = 0.739). Overall, the present study demonstrates genetic changes during LT and provides the potential for prognostic application.
  8. Cancer. 2022 May 25.
      BACKGROUND: The presence of TP53 mutations is associated with an unfavorable outcome in patients allografted for acute myeloid leukemia (AML), leading some to question the benefit of an allogeneic stem cell transplantation (allo-SCT) for this patient group, although this has not been studied in a large cohort.METHODS: A total of 780 patients with AML in first complete remission, with either intermediate- or adverse-risk cytogenetics, whose TP53 mutation status was reported, were included in this study from the European Society for Blood and Marrow Transplantation.
    RESULTS: Two-year overall survival (OS) was impaired in patients (n = 179) with evidence of a TP53 mutation at diagnosis (35.1%; 95% confidence interval [CI], 26.7-43.7) as compared to the cohort without (n = 601) (64%; 95% CI, 59.1-68.4; P = .001). In patients with mutant TP53 AML with no evidence of either chromosome 17p loss (17p-) and/or complex karyotype (CK) (n = 53, 29.6%), 2-year OS was 65.2% (95% CI, 48.4-77.6). This was not significantly different to patients without TP53 mutations. In patients with mutant TP53 AML with either 17p- and/or CK (n = 126, 70.4%), the OS was lower (24.6%; 95% CI, 16.2-34; P = .001).
    CONCLUSIONS: In summary, the adverse prognostic effect of TP53 mutations in AML following an allo-SCT is not evident in patients with neither co-occurring 17p- and/or CK, and these data inform decisions regarding allo-SCT in patients with TP53 mutant AML.
    Keywords:   TP53 ; acute myeloid; allogeneic stem cell transplant; cytogenetics; leukemia
  9. EBioMedicine. 2022 May 23. pii: S2352-3964(22)00240-7. [Epub ahead of print]80 104059
      BACKGROUND: Haploinsufficiency (HI) resulting from deletion of the long arm of chromosome 5 [del(5q)] and the accompanied loss of heterozygosity are likely key pathogenic factors in del(5q) myeloid neoplasia (MN) although the consequences of del(5q) have not been yet clarified.METHODS: Here, we explored mutations, gene expression and clinical phenotypes of 388 del(5q) vs. 841 diploid cases with MN [82% myelodysplastic syndromes (MDS)].
    FINDINGS: Del(5q) resulted as founder (better prognosis) or secondary hit (preceded by TP53 mutations). Using Bayesian prediction analyses on 57 HI marker genes we established the minimal del(5q) gene signature that distinguishes del(5q) from diploid cases. Clusters of diploid cases mimicking the del(5q) signature support the overall importance of del(5q) genes in the pathogenesis of MDS in general. Sub-clusters within del(5q) patients pointed towards the inherent intrapatient heterogeneity of HI genes.
    INTERPRETATION: The underlying clonal expansion drive results from a balance between the "HI-driver" genes (e.g., CSNK1A1, CTNNA1, TCERG1) and the proapoptotic "HI-anti-drivers" (e.g., RPS14, PURA, SIL1). The residual essential clonal expansion drive allows for selection of accelerator mutations such as TP53 (denominating poor) and CSNK1A1 mutations (with a better prognosis) which overcome pro-apoptotic genes (e.g., p21, BAD, BAX), resulting in a clonal expansion. In summary, we describe the complete picture of del(5q) MN identifying the crucial genes, gene clusters and clonal hierarchy dictating the clinical course of del(5q) patients.
    FUNDING: Torsten Haferlach Leukemia Diagnostics Foundation. US National Institute of Health (NIH) grants R35 HL135795, R01HL123904, R01 HL118281, R01 HL128425, R01 HL132071, and a grant from Edward P. Evans Foundation.
    Keywords:  5q deletion; CSNK1A1; Haploinsufficiency; Myelodysplastic syndromes; TP53
  10. Leuk Res. 2022 Jun;pii: S0145-2126(22)00083-2. [Epub ahead of print]117 106857
      Data concerning the treatment approach and clinical outcomes in younger patients with myelodysplastic syndromes (MDS) are lacking. Furthermore, published results from genomic profiling in the young adult MDS population are few. We identified patients aged 20-50 at diagnosis evaluated for de novo MDS at our institution over a 32-year period. Clinical information and results from sequencing panels were extracted for analysis. 68 eligible patients were found, including 32% with multilineage dysplasia and 29% with excess blasts-2 WHO subtypes. Revised International Prognostic Scoring System for MDS (IPSS-R) categorization had 47% high/very high-risk, and this classification held prognostic significance. The median overall survival was 59 months, and most patients (75%) underwent allogeneic hematopoietic cell transplantation (alloHCT). Thirty-four patients had mutational profiling; the most commonly mutated gene was TP53 and most commonly altered gene category was epigenetic regulators. Younger patients with de novo MDS represented a unique subset with high-risk disease features (adverse cytogenetics, higher R-IPSS) frequently observed along with alterations in TP53 and genes related to epigenetic and transcription pathways.
    Keywords:  Adolescent/young adult patients; Mutational profiling; Myelodysplastic syndromes
  11. Front Immunol. 2022 ;13 880108
      Immunotherapy with T-cells expressing bispecific T-cell engagers (ENG T-cells) is a promising approach to improve the outcomes for patients with recurrent/refractory acute myeloid leukemia (AML). However, similar to T-cells expressing chimeric antigen receptors (CARs), their antitumor activity is limited in the setting of chronic antigen stimulation. We therefore set out to explore whether transgenic expression of IL15 improves the effector function of ENG T-cells targeting CD123-positive AML. T-cells expressing CD123-specific ENG (CD123-ENG) ± IL15 were generated by retroviral transduction from peripheral blood T cells from healthy donors or patients with AML. In this study, we characterized in detail the phenotype and effector functions of ENG T-cell populations in vitro and in vivo. IL15-expressing CD123-ENG (CD123-ENG.IL15) T-cells retained their antigen-specificity and effector function in the setting of chronic antigen exposure for more 30 days of coculture with AML blasts in contrast to CD123-ENG T-cells, whose effector function rapidly eroded. Furthermore, CD123-ENG.IL15 T-cells remained in a less differentiated state as judged by a high frequency of naïve/memory stem T-cell-like cells (CD45RA+CCR7+/CD45RO-CD62L+ cells) without evidence of T-cell exhaustion. Single cell cytokine profiling using IsoPlexis revealed enhanced T-cell polyfunctionality of CD123-ENG.IL15 T-cells as judged by effector cytokine production, including, granzyme B, IFN-γ, MIP-1α, perforin, TNF-α, and TNF-β. In vivo, CD123-ENG.IL15 T-cells exhibited superior antigen-specific anti-AML activity and T-cell persistence in both peripheral blood and tissues (BM, spleens, and livers), resulting in a significant survival advantage in one AML xenograft model and two autologous AML PDX models. In conclusion, we demonstrate here that the expansion, persistence, and anti-AML activity of CD123-ENG T-cells can be significantly improved by transgenic expression of IL15, which promotes a naïve/TSCM-like phenotype. However, we also highlight that targeting a single tumor antigen (CD123) can lead to immune escape, reinforcing the need to develop approaches to target multiple antigens. Likewise, our study demonstrates that it is feasible to evaluate autologous T cells in AML PDX models, which will be critical for future preclinical evaluations of next generation AML-redirected T-cell therapies.
    Keywords:  AML; BiTE; CD123; IL15; T cells; immunotherapy
  12. Am J Hematol. 2022 May 26.
      The phase III study was designed to compare event-free survival (EFS) after treosulfan-based conditioning with a widely applied reduced-intensity conditioning (RIC) busulfan regimen in older or comorbid patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) undergoing allogeneic hematopoietic cell transplantation (HCT). A previously reported confirmatory interim analysis of the randomized clinical study including 476 patients demonstrated statistically significant non-inferiority for treosulfan with clinically meaningful improvement in EFS. Here, the final study results and pre-specified subgroup analyses of all 570 randomized patients with completed longer term follow-up are presented. Patients presenting HCT-specific comorbidity index > 2 or aged ≥ 50 years were randomly assigned (1:1) to intravenous (IV) fludarabine with either treosulfan (30 g/m2 IV) or busulfan (6.4 mg/kg IV) after stratification by disease risk group, donor type, and participating institution. The primary endpoint was EFS with disease recurrence, graft failure, or death from any cause as events. EFS of patients (median age 60 years) was superior after treosulfan compared to RIC busulfan: 36-months-EFS rate 59.5% (95% CI, 52.2 to 66.1) vs 49.7% (95% CI, 43.3 to 55.7) with a hazard ratio (HR) of 0.64 (95% CI, 0.49 to 0.84), P = 0.0006. Likewise, overall survival (OS) with treosulfan was superior compared to busulfan: 36-months-OS rate 66.8% vs 56.3%; HR 0.64 (95% CI, 0.48 to 0.87), P = 0.0037. Post hoc analyses revealed that these differences were consistent with the confirmatory interim analysis, and thereby the treosulfan regimen appears particularly suitable for older AML and MDS patients. This article is protected by copyright. All rights reserved.
  13. STAR Protoc. 2022 Jun 17. 3(2): 101400
      Severe congenital neutropenia (CN) is a pre-leukemic bone marrow failure syndrome that can progress to acute myeloid leukemia (CN/AML). Patient material to study leukemogenesis, especially hematopoietic progenitor cells (HPCs) is limited and hard to access. We have established a protocol for generation of HPCs from iPSCs followed by HPC expansion on Sl/Sl feeder cells expressing FLT3L. We performed drug treatment of iPSC-derived HPCs on feeder cells or under feeder-free conditions. Our protocol is also suitable for primary leukemia blasts. For complete details on the use and execution of this protocol, please refer to Dannenmann et al. (2021), (2020), and (2019).
    Keywords:  CRISPR; Cancer; Cell culture; Stem Cells
  14. Blood Adv. 2022 May 27. pii: bloodadvances.2022007033. [Epub ahead of print]
      Rapid and effective leucocyte response to infection is a fundamental function of the bone marrow (BM). However, with increasing age this response becomes impaired, resulting in an increased burden of infectious diseases. Here, we investigate how aging changes the metabolism and function of hematopoietic progenitor cells (HPCs) and the impact of the bone marrow niche on this phenotype. We found that, in response to LPS induced stress, HPC mitochondrial function is impaired and there is a failure to upregulate the TCA cycle in progenitor populations in aged animals compared to young animals. Furthermore, aged mesenchymal stromal cells (MSC) of the BM niche, but not HPCs, exhibit a senescent phenotype and selective depletion of senescent cells from the BM niche, as well as treatment with the senolytic drug ABT-263, improves mitochondrial function of HPCs when stressed with LPS. In summary, age related HPC metabolic dysfunction occurs indirectly as a 'bystander phenomenon' in the aging BM niche and can be restored by targeting senescent MSCs.
  15. Leukemia. 2022 May 25.
      Standardized monitoring of BCR::ABL1 mRNA levels is essential for the management of chronic myeloid leukemia (CML) patients. From 2016 to 2021 the European Treatment and Outcome Study for CML (EUTOS) explored the use of secondary, lyophilized cell-based BCR::ABL1 reference panels traceable to the World Health Organization primary reference material to standardize and validate local laboratory tests. Panels were used to assign and validate conversion factors (CFs) to the International Scale and assess the ability of laboratories to assess deep molecular response (DMR). The study also explored aspects of internal quality control. The percentage of EUTOS reference laboratories (n = 50) with CFs validated as optimal or satisfactory increased from 67.5% to 97.6% and 36.4% to 91.7% for ABL1 and GUSB, respectively, during the study period and 98% of laboratories were able to detect MR4.5 in most samples. Laboratories with unvalidated CFs had a higher coefficient of variation for BCR::ABL1IS and some laboratories had a limit of blank greater than zero which could affect the accurate reporting of DMR. Our study indicates that secondary reference panels can be used effectively to obtain and validate CFs in a manner equivalent to sample exchange and can also be used to monitor additional aspects of quality assurance.
  16. Leuk Res. 2022 May 11. pii: S0145-2126(22)00085-6. [Epub ahead of print]118 106859
      More than 90% of NPM1-mutated acute myeloid leukaemia (NPM1mut AML) patients have been determined to harbour other known concurrent mutations. However, there is limited data on the frequency of PTPN11 and its clinical impact in NPM1mut AML. Next-generation sequencing(NGS) was performed retrospectively on 112 genes in 254 patients with NPM1mut AML. Overall, 33 PTPN11 mutations were detected in 29 of the 254 patients (11.42%) screened. PTPN11 alterations were exclusively missense mutations affecting residues located within the N-SH2 (n = 25) and PTP (n = 8) domains and clustered overwhelmingly in exon 3 (n = 25). NPM1mut AML patients with mutant PTPN11 had significant associations with mutations in epigenetic regulators(TET2, IDH1/2, and DNMT3A) (72.41% vs. 46.67%, P = 0.009) and cohesins (RAD21,SMC1A, and SMC3)(10.34% vs. 1.33%, P = 0.02) compared to patients with wild-type PTPN11. Among the patients treated with intensive chemotherapy, the differences in disease-free survival (DFS) and overall survival (OS) between those with mutant and wild-type PTPN11 were not significant (P = 0.4, 0.83, respectively). In conclusion, PTPN11 mutations were frequently identified in NPM1mut AML patients and clustered in exon 3. PTPN11 mutations more frequently co-occurred with mutations involving epigenetic regulators but had no impact on prognosis.
    Keywords:  Acute myeloid leukemia; Mutation; NPM1; PTPN11
  17. Br J Haematol. 2022 May 25.
      Clonal cytopenia of undetermined significance (CCUS) is characterized by persistent cytopenias with genetic aberrations, which do not meet the diagnostic criteria for myelodysplastic syndrome (MDS). We aimed to compare the clinical and genetic characteristics of CCUS with lower-risk MDS and identify patients with CCUS with a high risk of progression. We performed targeted sequencing of bone marrow (BM) samples from patients with idiopathic cytopenia of undetermined significance (ICUS) (n = 139) and MDS (n = 226). Overall survival (OS) of patients with CCUS (n = 78) was worse than non-clonal ICUS (n = 61) and superior to lower-risk MDS (n = 99). Patients with CCUS showed similar characteristics to those with lower-risk MDS, except for higher haemoglobin, lower BM cellularity, and less frequent SF3B1 mutations. Lower haemoglobin, DDX41 (biallelic germline and somatic), ETV6, and RUNX1 mutations were independent prognostic factors for worse OS. Lower haemoglobin and DDX41 mutations were also associated with lower progression-free survival. Patients with CCUS with high-risk features showed similar or worse OS than patients with lower-risk MDS. Our findings suggest that patients with CCUS having certain clinical or genetic features should be regarded and treated as lower-risk MDS despite lacking significant dysplasia or MDS-associated chromosomal abnormalities.
    Keywords:  DDX41; clonal cytopenia of undetermined significance; idiopathic cytopenia of undetermined significance; myelodysplastic syndrome
  18. Blood. 2022 May 24. pii: blood.2022015708. [Epub ahead of print]
      Clinically tolerable, permissive HLA-DPB1 mismatches defined by the T-cell epitope (TCE) model improve the selection of unrelated donors in allogeneic hematopoietic cell transplantation (HCT). Mechanistically, overlapping immunopeptidomes in structurally close HLA-DP allotypes with similar peptide-binding motifs are fundamental for permissiveness in vitro, but their relevance in vivo is still unknown. Here, we hypothesized that a similarity measure reflecting the peptide-binding region of HLA-DPB1 alleles could constitute a proxy for immunopeptidome overlap and hence predict permissive mismatches in the clinical setting. To test this, we used multidimensional scaling techniques based on 28 polymorphic amino acid positions, resulting in the stratification of HLA-DPB1 alleles from the heterogeneous TCE group 3 (TCE3) into a subgroup of four frequent, structurally related, and less immunogenic "core" TCE3 alleles compared to the remaining "non-core" alleles. In a CIBMTR cohort of 5140 10/10-matched patients transplanted for AML, ALL, or MDS from 2008-2017, the risks of aGVHD II-IV increased progressively from "core" TCE3 permissive (N=930; HR 1.12 [0.98-1.28]; p=0.1012) to "non-core" TCE3-permissive (N=1286; HR 1.24 [1.06-1.46]; p= 0.0082), and non-permissive mismatches (N=2023; HR 1.32 [1.16-1.50]; p<.0001) compared to allele-matched patients (N=785). "Core" TCE3-permissive pairs (HR 0.78 [0.68-0.88]; p=0.0002), but not "non-core" TCE3-permissive pairs (HR 0.95 [0.83-1.09]; p=0.4578) showed significantly lower risks of TRM when compared to non-permissive pairs. Our results suggest that frequent mismatches between structurally similar "core" HLA-DPB1 alleles are the main drivers of permissiveness after HCT, and provide evidence for a role of immunopeptidome differences between mismatched HLA-DPB1 alleles in the clinical outcome of HCT.
  19. Leukemia. 2022 May 21.
      The cyclin-dependent kinase (CDK) inhibitor p27Kip1 regulates cell proliferation. Phosphorylation of tyrosine residue 88 (Y88) converts the inhibitor into an assembly factor and activator of CDKs, since Y88-phosphorylation restores activity to cyclin E,A/CDK2 and enables assembly of active cyclin D/CDK4,6. To investigate the physiological significance of p27 tyrosine phosphorylation, we have generated a knock-in mouse model where Y88 was replaced by phenylalanine (p27-Y88F). Young p27-Y88F mice developed a moderately reduced body weight, indicative for robust CDK inhibition by p27-Y88F. When transformed with v-ABL or BCR::ABL1p190, primary p27-Y88F cells are refractory to initial transformation as evidenced by a diminished outgrowth of progenitor B-cell colonies. This indicates that p27-Y88 phosphorylation contributes to v-ABL and BCR::ABL1p190 induced transformation. Surprisingly, p27-Y88F mice succumbed to premature v-ABL induced leukemia/lymphoma compared to p27 wild type animals. This was accompanied by a robust reduction of p27-Y88F levels in v-ABL transformed cells. Reduced p27-Y88F levels seem to be required for efficient cell proliferation and may subsequently support accelerated leukemia progression. The potent downregulation p27-Y88F levels in all leukemia-derived cells could uncover a novel mechanism in human oncogenesis, where reduced p27 levels are frequently observed.
  20. Haematologica. 2022 May 26.
      Discontinuation of tyrosine kinase inhibitors in chronic phase chronic myeloid leukemia is feasible in clinical practice based on recently published international recommendations. Nevertheless, predictive factors of molecular recurrence are not fully elucidated and long term follow-up of patients enrolled in clinical studies are required in order to update knowledge on discontinuation attempts particularly in terms of the safety and durability of treatment-free remission (TFR). In the current study, we updated results from the STIM2 study in the light of the consensual criterion of Molecular Recurrence (MRec) reported in different international recommendations. One hundred and eight patients lost MMR among the 199 patients included in the per protocol study. TFR probability was 43.4% [36.3-50.4] at 5 years, 40.9% [32.8-47.3] at 7 years and 34.5% [25.6-43.3] at 9 years with a median follow-up of 40.8 months (5.5-111 months). MRec occurred between 0 to 6 months, 6 to 24 months and after 24 months in 75 pts (69%), 15 pts (14%) and 18 pts (17%) respectively. Notably, the kinetics of MRec differed significantly between these 3 subgroups with a median time from loss of MR4 to MMR loss of 1, 7 and 22 months respectively. Predictive factors of MRec differed according to the time of occurrence of MRec. Imatinib treatment and deep molecular response durations and BCR::ABL1/ABL1 levels at TKI cessation as quantified by RT-ddPCR are involved in MRec occurring up to 24 months but not beyond. ( Identifier NCT#0134373).
  21. Cancer Genet. 2022 May 18. pii: S2210-7762(22)00085-0. [Epub ahead of print]266-267 7-14
      Jumping translocations (JT) are rare chromosomal rearrangements caused by the translocation of one donor chromosome segment to two or more recipient chromosomes. In the setting of myeloid neoplasms, JT are typically associated with disease transformation to acute myeloid leukemia (AML), and studies to date have found JT to be associated with poor prognosis and short overall survival. However, JT have been only very rarely reported in AML associated with a favorable AML prognostic cytogenetic marker. Additionally, JT have infrequently been described in hematological malignancies associated with autoimmune diseases (AID) such as Crohn's Disease (CD). Here we describe a case of a 40-year-old female with a 24-year history of CD diagnosed with AML harbouring the inv(16)(p13.1q22)/CBFB-MYH11 rearrangement in conjunction with sideline clones containing trisomy 13, tetrasomy 13, and a JT of chromosome 13q12 jumping to 7q32 and 18p11.2. The patient attained molecular remission one month post diagnosis after induction 7 + 3 chemotherapy. Morphologic relapse of disease occurred 27 months post diagnosis. A second molecular remission was attained 3 months later after re-induction chemotherapy. The patient received a sibling bone marrow transplant 32 months post diagnosis and is currently in remission 7 months post allogeneic transplant. To the best of our knowledge, this case represents the first report of JT occurring in inv(16)(p13.1q22)/CBFB-MYH11 AML and the second of JT occurring in an AML patient with prior clinical history of CD. This case provides further insight into the rare occurrence of JT in AML, particularly AML with a favorable cytogenetic marker in conjunction with AID.
    Keywords:  AML; CBFB-MYH11; Crohn's Disease; Jumping translocation; inv(16)(p13.1q22)
  22. STAR Protoc. 2022 Jun 17. 3(2): 101408
      Metabolism is important for the regulation of hematopoietic stem cells (HSCs) and drives cellular fate. Due to the scarcity of HSCs, it has been technically challenging to perform metabolome analyses gaining insight into HSC metabolic regulatory networks. Here, we present two targeted liquid chromatography-mass spectrometry approaches that enable the detection of metabolites after fluorescence-activated cell sorting when sample amounts are limited. One protocol covers signaling lipids and retinoids, while the second detects tricarboxylic acid cycle metabolites and amino acids. For complete details on the use and execution of this protocol, please refer to Schönberger et al. (2022).
    Keywords:  Mass Spectrometry; Metabolomics; Stem Cells
  23. Lancet Haematol. 2022 May 18. pii: S2352-3026(22)00102-8. [Epub ahead of print]
      BACKGROUND: The phase 3b, randomised, open-label RESPONSE-2 study in patients with inadequately controlled polycythaemia vera without splenomegaly showed superiority of the Janus kinase (JAK) 1 and JAK2 inhibitor ruxolitinib versus best available therapy for the primary endpoint of haematocrit control at week 28. Here, we present secondary endpoints of the RESPONSE-2 study after 5 years of follow-up.METHODS: RESPONSE-2 was an open-label, randomised, phase 3b study done at 48 hospitals or clinics across 12 countries in Asia, Australia, Europe, and Canada. Patients (aged ≥18 years) with polycythaemia vera without splenomegaly, who were intolerant of, or resistant to hydroxyurea, with an Eastern Cooperative Oncology Group performance status of 2 or less were randomly assigned (1:1) to receive ruxolitinib or best available therapy for up to 80 weeks. Patients received oral ruxolitinib at a starting dose of 10 mg twice a day or best available therapy. Patients assigned to best available therapy could cross over to ruxolitinib at week 28 if the primary endpoint was not met, or after week 28 and up to week 80 if best available therapy was ineffective or not tolerated. Patients receiving ruxolitinib at week 80, including crossover patients, could continue ruxolitinib treatment up to week 260. We assessed secondary endpoints at week 260, including durable haematocrit control, median duration of haematocrit control, median haematocrit level over time, number of phlebotomies, and overall survival. Analyses were based on the intention-to-treat principle. This study is registered with, NCT02038036 and was completed on April 7, 2020.
    FINDINGS: Patients were enrolled between March 25, 2014 and Feb 11, 2015. 149 patients were randomly assigned to ruxolitinib (n=74) or best available therapy (n=75). The median follow-up was 67 months (IQR 65-70). At randomisation, best available therapy regimens included hydroxyurea (n=38), interferon or pegylated interferon (n=9), pipobroman (n=5), lenalidomide (n=1), or no treatment (n=22). Between weeks 28 and 80, 58 (77%) of 75 patients in the best available therapy group crossed over to ruxolitinib; no patients continued best available therapy after week 80 per protocol. 97 patients received ruxolitinib until week 260, including 59 (80%) of 74 patients in the ruxolitinib group and 38 (66%) of 58 patients in the crossover groups. At week 260, 16 (22%; 95% CI 13-33) of 74 patients in the ruxolitinib group had achieved durable haematocrit control, with estimated median duration not reached (NR; 95% CI 144 to NR). Median duration of haematocrit control was not reported for patients in the best available therapy group due to the small number of responders by week 80. During the 5-year follow-up, median haematocrit level among patients in the ruxolitinib group remained below 45%. 60 phlebotomies were required among 74 patients in the ruxolitinib group in 260 weeks, and 106 phlebotomies among 75 patients in the best available therapy group in 80 weeks. 5-year overall survival was 96% (95% CI 87-99) in the ruxolitinib group and 91% (80-96) in the best available therapy group. The most common grade 3-4 adverse events (exposure-adjusted per 100 patient-years) in the ruxolitinib group (n=74) and best available therapy group (n=75) were hypertension (eight [2·4%] vs three [5·6%]), thrombocytopenia (one [0·3%] vs three [5·6%]), and thrombocytosis (0 vs four [7·5%]). Exposure-adjusted rates of any-grade thromboembolic events were 1·5% per 100 person-years (five of 74 patients) in the ruxolitinib group and 3·7% per 100 person-years (two of 75 patients) in the best available therapy group. No treatment-related deaths occurred during the study.
    INTERPRETATION: 5-year results from the RESPONSE-2 study support the use of ruxolitinib as a second-line therapy of choice for patients with inadequately controlled polycythaemia vera without splenomegaly.
    FUNDING: Novartis.