bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2022‒07‒24
27 papers selected by
Paolo Gallipoli
Barts Cancer Institute, Queen Mary University of London

  1. Blood. 2022 Jul 13. pii: blood.2021014241. [Epub ahead of print]
      BCL-2 inhibition has been shown to be effective in acute myeloid leukemia (AML) in combination with hypomethylating agents or low-dose cytarabine. However, resistance and relapse represent major clinical challenges. Thus, there is an unmet need to overcome resistance to current venetoclax-based strategies. We performed high-throughput drug screening to identify effective combination partners for venetoclax in AML. Overall, 64 anti-leukemic drugs were screened in 31 primary high-risk AML samples with or without venetoclax. Gilteritinib exhibited highest synergy with venetoclax in FLT3 wildtype AML. The combination of gilteritinib and venetoclax increased apoptosis, reduced viability, and was active in venetoclax-azacitidine resistant cell lines and primary patient samples. Proteomics revealed increased FLT3 wildtype signaling in specimens with low in-vitro response to the currently used venetoclax-azacitidine combination. Mechanistically, venetoclax with gilteritinib decreased phosphorylation of ERK and GSK3B via combined AXL and FLT3 inhibition with subsequent suppression of the antiapoptotic protein MCL-1. MCL-1 downregulation was associated with increased MCL-1 phosphorylation of serine 159, decreased phosphorylation of threonine 161 and proteasomal degradation. Gilteritinib and venetoclax were active in a FLT3 wildtype AML PDX model with TP53 mutation and reduced leukemic burden in four FLT3 wildtype AML patients receiving venetoclax-gilteritinib off-label after developing refractory disease under venetoclax-azacitidine. In summary, our results suggest that combined inhibition of FLT3/AXL potentiates venetoclax response in FLT3-wildtype AML by inducing MCL-1 degradation. Thus, the venetoclax-gilteritinib combination merits testing as potentially active regimen in high-risk AML patients with FLT3 wildtype.
  2. J Clin Oncol. 2022 Jul 18. JCO2200602
      PURPOSE: The FMS-related tyrosine kinase 3 (FLT3) inhibitor gilteritinib is standard therapy for relapsed/refractory FLT3-mutated (FLT3mut) acute myeloid leukemia (AML) but seldom reduces FLT3mut burden or induces sustained efficacy. Gilteritinib combines synergistically with the BCL-2 inhibitor venetoclax in preclinical models of FLT3mut AML.METHODS: This phase Ib open-label, dose-escalation/dose-expansion study ( identifier: NCT03625505) enrolled patients with FLT3 wild-type and FLT3mut (escalation) or FLT3mut (expansion) relapsed/refractory AML. Patients received 400 mg oral venetoclax once daily and 80 mg or 120 mg oral gilteritinib once daily. The primary objectives were safety, identification of the recommended phase II dose, and the modified composite complete response (mCRc) rate (complete response [CR] + CR with incomplete blood count recovery + CR with incomplete platelet recovery + morphologic leukemia-free state) using ADMIRAL phase III-defined response criteria.
    RESULTS: Sixty-one patients were enrolled (n = 56 FLT3mut); 64% (n = 36 of 56) of FLT3mut patients had received prior FLT3 inhibitor therapy. The recommended phase II dose was 400 mg venetoclax once daily and 120 mg gilteritinib once daily. The most common grade 3/4 adverse events were cytopenias (n = 49; 80%). Adverse events prompted venetoclax and gilteritinib dose interruptions in 51% and 48%, respectively. The mCRc rate for FLT3mut patients was 75% (CR, 18%; CR with incomplete blood count recovery, 4%; CR with incomplete platelet recovery, 18%; and morphologic leukemia-free state, 36%) and was similar among patients with or without prior FLT3 inhibitor therapy (80% v 67%, respectively). The median follow-up was 17.5 months. The median time to response was 0.9 months, and the median remission duration was 4.9 months (95% CI, 3.4 to 6.6). FLT3 molecular response (< 10-2) was achieved in 60% of evaluable mCRc patients (n = 15 of 25). The median overall survival for FLT3mut patients was 10.0 months.
    CONCLUSION: The combination of venetoclax and gilteritinib was associated with high mCRc and FLT3 molecular response rates regardless of prior FLT3 inhibitor exposure. Dose interruptions were needed to mitigate myelosuppression.
  3. EJHaem. 2022 May;3(2): 426-433
      Internal tandem duplication of the Feline McDonough Sarcoma (FMS)-like tyrosine kinase 3 (FLT3-ITD) is one of the most clinically relevant mutations in acute myeloid leukemia (AML), with a high FLT3-ITD allelic ratio (AR) (≥0.5) being strongly associated with poor prognosis. FLT3-ITDs are heterogeneous, varying in size and location, with some patients having multiple FLT3-ITDs. Bulk cell-based approaches are limited in their ability to reveal the clonal structure in such cases. Using single-cell proteogenomic sequencing (ScPGseq), we attempted to identify a relapse-fated subclone in an AML case with mutations in WT1, NPM1, and FLT3 tyrosine kinase domain and two FLT3-ITDs (21 bp and 39 bp) (low AR) at presentation, then relapsed only with WT1 and NPM1 mutations and one FLT3-ITD (high AR). This relapse-fated subclone at presentation (∼2.1% of sequenced cells) was characterized by the presence of a homozygous 21 bp FLT3-ITD resulting from copy neutral loss of heterozygosity (CN-LOH) of chr13q and an aberrant, immature myeloid cell surface signature, contrast to the cell surface phenotype at presentation. In contrast to results from multicolor flow-cytometry, ScPGseq not only enabled the early detection of rare relapse-fated subclone showing immature myeloid signature but also highlighted the presence of homozygous 21 bp FLT3-ITDs in the clone at presentation.
    Keywords:  AML; molecular diagnostics; prognostic factors; single cell
  4. Blood. 2022 Jul 19. pii: blood.2022016082. [Epub ahead of print]
      Patients with acute myeloid leukemia (AML) often achieve remission after allogeneic hematopoietic cell transplantation (allo-HCT), but subsequently die of relapse that is driven by leukemia cells resistant to elimination by allogeneic T-cells based on decreased MHC-II expression and apoptosis-resistance. Here we demonstrate that mouse-double-minute-2 (MDM2)-inhibition can counteract immune evasion of AML. MDM2-inhibition induced MHC class I and II expression in murine and human AML cells. Using xenografts of human AML and syngeneic mouse models of leukemia, we show that MDM2-inhibition enhanced cytotoxicity against leukemia cells and improved survival. MDM2-inhibition also led to increases in TRAIL-R1/2 on leukemia cells and higher frequencies of CD8+CD27lowPD-1lowTIM-3low T-cells, with features of cytotoxicity (Perforin+CD107a+TRAIL+) and longevity (bcl-2+IL-7R+). CD8+ T-cells isolated from leukemia-bearing MDM2-inhibitor treated allo-HCT recipients exhibited higher glycolytic activity and enrichment for nucleotides and their precursors compared to vehicle-controls. T-cells isolated from MDM2-inhibitor treated AML bearing mice eradicated leukemia in secondary AML-bearing recipients. Mechanistically, the MDM2-inhibitor mediated effects were p53-dependent because p53-knockdown abolished TRAIL-R1/2 and MHC-II-upregulation, while p53-binding to TRAILR1/2-promotors increased upon MDM2-inhibition. The observations in the mouse models were complemented by data from human individuals. Patient-derived AML-cells exhibited increased TRAIL-R1/2 and MHC-II expression upon MDM2-inhibition. In summary, we identified a targetable vulnerability of AML cells to allogeneic T-cell-mediated cytotoxicity, through restoration of p53-dependent TRAIL-R1/2 and MHC-II-production via MDM2-inhibition.
  5. Front Oncol. 2022 ;12 924567
      Acute myeloid leukaemia (AML) is a highly proliferative cancer characterised by infiltration of immature haematopoietic cells in the bone marrow (BM). AML predominantly affects older people and outcomes, particularly in this difficult to treat population remain poor, in part due to inadequate response to therapy, and treatment toxicity. Normal haematopoiesis is supported by numerous support cells within the BM microenvironment or niche, including adipocytes, stromal cells and endothelial cells. In steady state haematopoiesis, haematopoietic stem cells (HSCs) primarily acquire ATP through glycolysis. However, during stress-responses HSCs rapidly transition to oxidative phosphorylation, enabled by mitochondrial plasticity. Historically it was thought that cancer cells preferentially used glycolysis for ATP production, however recently it has become evident that many cancers, including AML primarily use the TCA cycle and oxidative phosphorylation for rapid proliferation. AML cells hijack the stress-response pathways of their non-malignant counterparts, utilising mitochondrial changes to drive expansion. In addition, amino acids are also utilised by leukaemic stem cells to aid their metabolic output. Together, these processes allow AML cells to maximise their ATP production, using multiple metabolites and fuelling rapid cell turnover which is a hallmark of the disease. This review of AML derived changes in the BM niche, which enable enhanced metabolism, will consider the important pathways and discuss future challenges with a view to understanding how AML cells are able to hijack metabolic pathways and how we may elucidate new targets for potential therapies.
    Keywords:  acute myeloid leukaemia; adipocytes; bone marrow niche; free fattty acids; metabolism
  6. Future Oncol. 2022 Jul 19.
      Prevention of relapse is a major therapeutic challenge and an unmet need for patients with acute myeloid leukemia (AML). Venetoclax is a highly selective, potent, oral BCL-2 inhibitor that induces apoptosis in AML cells. When combined with azacitidine, it leads to prolonged overall survival and rapid, durable remissions in treatment-naive AML patients ineligible for intensive chemotherapy. VIALE-M is a randomized, double-blind, two-arm study to evaluate the safety and efficacy of venetoclax in combination with oral azacitidine (CC-486) as maintenance therapy in patients in complete remission with incomplete blood count recovery after intensive induction and consolidation therapies. The primary end point is relapse-free survival. Secondary outcomes include overall survival, minimal residual disease conversion and improvement in quality-of-life. Trial registration number: NCT04102020 (
    Keywords:  BCL-2 inhibitor; CC-486 (oral azacitidine); acute myeloid leukemia; first remission; maintenance therapy; minimal residual disease conversion; phase III; relapse-free survival; venetoclax
  7. Curr Opin Oncol. 2022 Jul 16.
      PURPOSE OF REVIEW: Venetoclax in combination with nucleoside analogs such as hypomethylating agents (HMA) and low-dose cytarabine (LDAC) has led to unprecedented response and survival outcomes in patients with acute myeloid leukemia (AML). This has spurred the development of regimens combining venetoclax with other nucleoside analogs with distinct mechanisms of action. Here, we review older and newer nucleoside analogs, the rationale for their combination with venetoclax, and clinical evidence for the combination when available.RECENT FINDINGS: Venetoclax with HMA prolonged survival in a phase 3 study. Additionally, biologic correlates of response and resistance to venetoclax with HMA have been identified. The addition of venetoclax to standard intensive regimens containing higher doses of cytarabine and purine nucleoside analogs are safe and induce very high rates of remission and measurable residual disease negativity (MRD) negativity in newly diagnosed and relapsed/refractory AML. Investigational nucleoside analogs aim to improve upon the safety, bioavailability, or efficacy of approved venetoclax combinations and are currently being evaluated in clinical studies.
    SUMMARY: The development of venetoclax with HMA has transformed care for elderly adults with AML and opened the door for novel combinations of venetoclax with other nucleoside analogs. Further clinical studies are needed to see if these novel combinations further improve outcomes in AML particularly for patients with high-risk disease.
  8. Front Oncol. 2022 ;12 896426
      Acute myeloid leukemia (AML) is a polyclonal and heterogeneous hematological malignancy. Relapse and refractory after induction chemotherapy are still challenges for curing AML. Leukemia stem cells (LSCs), accepted to originate from hematopoietic stem/precursor cells, are the main root of leukemogenesis and drug resistance. LSCs are dynamic derivations and possess various elusive resistance mechanisms. In this review, we summarized different primary resistance and remolding mechanisms of LSCs after chemotherapy, as well as the indispensable role of the bone marrow microenvironment on LSCs resistance. Through a detailed and comprehensive review of the spectacle of LSCs resistance, it can provide better strategies for future researches on eradicating LSCs and clinical treatment of AML.
    Keywords:  LSCs remolding; acute myeloid leukemia; clonal heterogeneity; drug resistance; leukemia stem cells; resistant mechanisms
  9. Leukemia. 2022 Jul 18.
      Measurable residual disease (MRD) detected by multiparametric flow cytometry (MFC) is associated with unfavorable outcome in patients with AML. A simple, broadly applicable eight-color panel was implemented and analyzed utilizing a hierarchical gating strategy with fixed gates to develop a clear-cut LAIP-based DfN approach. In total, 32 subpopulations with aberrant phenotypes with/without expression of markers of immaturity were monitored in 246 AML patients after completion of induction chemotherapy. Reference values were established utilizing 90 leukemia-free controls. Overall, 73% of patients achieved a response by cytomorphology. In responders, the overall survival was shorter for MRDpos patients (HR 3.8, p = 0.006). Overall survival of MRDneg non-responders was comparable to MRDneg responders. The inter-rater-reliability for MRD detection was high with a Krippendorffs α of 0.860. The mean time requirement for MRD analyses at follow-up was very short with 04:31 minutes. The proposed one-tube MFC approach for detection of MRD allows a high level of standardization leading to a promising inter-observer-reliability with a fast turnover. MRD defined by this strategy provides relevant prognostic information and establishes aberrancies outside of cell populations with markers of immaturity as an independent risk feature. Our results imply that this strategy may provide the base for multicentric immunophenotypic MRD assessment.
  10. Leukemia. 2022 Jul 22.
      Treatment results of AML in elderly patients are unsatisfactory. In an open label randomized phase II study, we investigated whether addition of the XPO1 inhibitor selinexor to intensive chemotherapy would improve outcome in this population. 102 AML patients > 65 years of age (median 69 (65-80)) were randomly assigned to standard chemotherapy (3 + 7) with or without oral selinexor 60 mg twice weekly (both arms n = 51), days 1-24. In the second cycle, cytarabine 1000 mg/m2 twice daily, days 1-6 with or without selinexor was given. CR/CRi rates were significantly higher in the control arm than in the investigational arm (80% (95% C.I. 69-91%) vs. 59% (45-72%; p = 0.018), respectively). At 18 months, event-free survival was 45% for the control arm versus 26% for the investigational arm (Cox-p = 0.012) and overall survival 58% vs. 33%, respectively (p = 0.009). AML and infectious complications accounted for an increased death rate in the investigational arm. Irrespective of treatment, MRD status after two cycles appeared to be correlated with survival. We conclude that the addition of selinexor to standard chemotherapy does negatively affect the therapeutic outcome of elderly AML patients. (Netherlands Trial Registry number NL5748 (NTR5902), ).
  11. Histopathology. 2022 Jul 23.
      AIMS: TP53-mutated acute myeloid leukemia (AML) is associated with an adverse prognosis and poor response to traditional chemotherapy regimens. Next generation sequencing (NGS) is considered the gold standard method to determine TP53-mutational status; however, molecular assays are costly and time consuming. In contrast, immunohistochemistry (IHC) can be performed within one day of biopsy. We sought to determine an optimal threshold of staining with p53 IHC to predict TP53-mutational status.METHODS AND RESULTS: We identified 142 consecutive patients with newly diagnosed AML with concurrent NGS analysis diagnosed between 2019 and 2020. All cases were stained for p53 IHC and images were scored for the percent of strongly stained p53+ cells by a combination of manual counting and image analysis. We then correlated percent positive staining with mutational status and clinical outcomes. We determined that a threshold of ≥7% strongly stained cells by p53 IHC correlated with the presence of a TP53 mutation with a sensitivity of 67%, specificity of 100%, PPV of 100% and NPV of 90%. TP53 mutation and the presence of ≥7% staining by IHC were associated with shorter overall survival (OS) by univariate analysis (p<0.01).
    CONCLUSIONS: If the limitations of this study are carefully considered, our findings suggest that p53 protein expression as evaluated by IHC could be used to rapidly predict TP53-mutational status with high specificity and assist in risk stratification in newly diagnosed AML.
    Keywords:  TP53; acute myeloid leukemia; immunohistochemistry
  12. Cancer Cell. 2022 Jul 20. pii: S1535-6108(22)00312-9. [Epub ahead of print]
      Acute myeloid leukemia (AML) is a cancer of myeloid-lineage cells with limited therapeutic options. We previously combined ex vivo drug sensitivity with genomic, transcriptomic, and clinical annotations for a large cohort of AML patients, which facilitated discovery of functional genomic correlates. Here, we present a dataset that has been harmonized with our initial report to yield a cumulative cohort of 805 patients (942 specimens). We show strong cross-cohort concordance and identify features of drug response. Further, deconvoluting transcriptomic data shows that drug sensitivity is governed broadly by AML cell differentiation state, sometimes conditionally affecting other correlates of response. Finally, modeling of clinical outcome reveals a single gene, PEAR1, to be among the strongest predictors of patient survival, especially for young patients. Collectively, this report expands a large functional genomic resource, offers avenues for mechanistic exploration and drug development, and reveals tools for predicting outcome in AML.
    Keywords:  JEDI; LSC17; MEGF12; cell state; eigengene; hematologic malignancy; leukemia stem cell; monocyte; targeted therapy
  13. J Med Chem. 2022 Jul 22.
      We previously identified two structurally related pyrazolone (compound 1) and pyridazine (compound 2) allosteric inhibitors of DNMT3A through screening of a small chemical library. Here, we show that these compounds bind and disrupt protein-protein interactions (PPIs) at the DNMT3A tetramer interface. This disruption is observed with distinct partner proteins and occurs even when the complexes are acting on DNA, which better reflects the cellular context. Compound 2 induces differentiation of distinct myeloid leukemia cell lines including cells with mutated DNMT3A R882. To date, small molecules targeting DNMT3A are limited to competitive inhibitors of AdoMet or DNA and display extreme toxicity. Our work is the first to identify small molecules with a mechanism of inhibition involving the disruption of PPIs with DNMT3A. Ongoing optimization of compounds 1 and 2 provides a promising basis to induce myeloid differentiation and treatment of diseases that display aberrant PPIs with DNMT3A, such as acute myeloid leukemia.
  14. EJHaem. 2021 Nov;2(4): 823-833
      In the field of AML, the early 2000s were shaped by the advent of novel molecular biology technologies including high-throughput sequencing that improved prognostic classification, response evaluation through the quantification of minimal residual disease, and the launch of research on targeted therapies. Our knowledge of leukemogenesis, AML genetic diversity, gene-gene interactions, clonal evolution, and treatment response assessment has also greatly improved. New classifications based on chromosomal abnormalities and gene mutations are now integrated on a routine basis. These considerable efforts contributed to the discovery and development of promising drugs which specifically target gene mutations, apoptotic pathways and cell surface antigens as well as reformulate classical cytotoxic agents. In less than 2 years, nine novels drugs have been approved for the treatment of AML patients, and many others are being intensively investigated, in particular immune therapies. There are now numerous clinical research opportunities offered to clinicians, thanks to these new treatment options. We are only at the start of a new era which should see major disruptions in the way we understand, treat, and monitor patients with AML.
    Keywords:  CPX‐351; FLT3 inhibitors; IDH inhibitors; TP53; acute myeloid leukemia; enasidenib; gemtuzumab ozogamycin; gilteritinib; glasdegib; ivosidenib; midostaurin; monoclonal antibodies; oral azacitidine; venetoclax
  15. Mol Cell Biochem. 2022 Jul 20.
      Acute myeloid leukemia (AML) is a type of hematologic diseases, which is related to abnormal genes. The aberrant microtubule actin cross-linking factor 1 (MACF1) is associated with progression of multiple tumors by initiating cell proliferation. Nevertheless, the function and action mechanism of MACF1 in AML cell proliferation remain mostly unknown. Our study aimed to explore the influence of MACF1 on AML cell proliferation by CCK-8 and EdU staining assays. Moreover, we aimed to explore the effect of MACF1 on downstream Runx2 and the PI3K/Akt signaling. MACF1 expression in AML patients was predicted by bioinformatics analysis. Cells were transfected with si-con, si-MACF1 or Runx2 using Lipofectamine 2000. Upregulated MACF1 was found in AML patients and predicted worse overall survival. MACF1 expression was upregulated in AML cells compared with that in hematopoietic stem and progenitor cells. MACF1 silencing reduced AML cell proliferation. Runx2 level was increased in AML cells, and decreased by silencing MACF1. Runx2 upregulation rescued MACF1 silencing-mediated inhibition of proliferation. MACF1 downregulation inhibited activation of the PI3K/Akt pathway by decreasing Runx2. Activation of the PI3K/Akt pathway abrogated the suppressive role of MACF1 downregulation in AML cell proliferation. In conclusion, MACF1 knockdown decreased AML cell proliferation by reducing Runx2 and inactivating the PI3K/Akt signaling.
    Keywords:  Acute myeloid leukemia; MACF1; PI3K/Akt; Proliferation; Runx2
  16. Sci Rep. 2022 Jul 20. 12(1): 12410
      Aberrant changes in 5-hydroxymethylcytosine (5hmC) are a unique epigenetic feature in many cancers including acute myeloid leukemia (AML). However, genome-wide analysis of 5hmC in plasma cell-free DNA (cfDNA) remains unexploited in AML patients. We used a highly sensitive and robust nano-5hmC-Seal technology and profiled genome-wide 5hmC distribution in 239 plasma cfDNA samples from 103 AML patients and 81 non-cancer controls. We developed a 5hmC diagnostic model that precisely differentiates AML patients from controls with high sensitivity and specificity. We also developed a 5hmC prognostic model that accurately predicts prognosis in AML patients. High weighted prognostic scores (wp-scores) in AML patients were significantly associated with adverse overall survival (OS) in both training (P = 3.31e-05) and validation (P = 0.000464) sets. The wp-score was also significantly associated with genetic risk stratification and displayed dynamic changes with varied disease burden. Moreover, we found that high wp-scores in a single gene, BMS1 and GEMIN5 predicted OS in AML patients in both the training set (P = 0.023 and 0.031, respectively) and validation set (P = 9.66e-05 and 0.011, respectively). Lastly, our study demonstrated the genome-wide landscape of DNA hydroxymethylation in AML and revealed critical genes and pathways related to AML diagnosis and prognosis. Our data reveal plasma cfDNA 5hmC signatures as sensitive and accurate markers for AML diagnosis and prognosis. Plasma cfDNA 5hmC analysis will be an effective and minimally invasive tool for AML management.
  17. Haematologica. 2022 Jul 21.
      Time at home is a critically important outcome to adults with acute myeloid leukemia (AML) when selecting treatment; however, no study to date has adequately described the amount of time older adults spend at home following initiation of chemotherapy. We queried records from a multi-institution health system to identify adults age ≥60 newly diagnosed with AML treated with azacitidine (AZA) or venetoclax (VEN) and evaluated the proportion of days at home (PDH) following diagnosis. Days were considered "at home" if patients were not admitted or seen in the emergency department or oncology/infusion clinic. Assessed covariates included demographics and disease risk. Associations between PDH and baseline characteristics were evaluated via linear regression, adjusted for log length of follow-up. From 2015-2020, 113 older adults were identified. Most received AZA+VEN (51.3%) followed by AZA monotherapy (38.9%). Mean PDH for all patients was 0.58 (95% confidence interval 0.54-0.63, median 0.63). PDH increased among survivors over time. PDH did not differ between therapy groups (adjusted mean, AZA+VEN: 0.68; AZA monotherapy: 0.66; p=0.64) or between disease risk categories (p=0.34). Compared to AZA monotherapy, patients receiving AZA+VEN had longer clinic visits (median minutes: 127.9 vs. 112.9, p.
  18. EJHaem. 2020 Jul;1(1): 79-85
      Optimizing the induction therapy of acute myeloid leukemia (AML) may improve the remission rate and reduce the risk of relapse, thereby extend survival. Cyclophosphamide (CTX) shows benefit in treating relapsed and refractory AML patients, but it has not been reported in first-line induction regimens. To assess the efficacy and safety of CTX and moderate-dosage cytarabine (Ara-C) as induction chemotherapy in newly diagnosed adult AML, 40 patients were enrolled to receive CTX (20 mg/kg/d) for 4 consecutive days and Ara-C for 3 (1 g/m2 q12h, CA4+3) or 5 (1 g/m2 qd, CA4+5) days. With one course of induction chemotherapy, the overall response rate and the complete remission rate (CR) was 82.5% (33/40) and 77.5% (31/40), respectively. The expected 5 years overall survival and relapse-free survival was 64% in patients experienced CR and fulfilled consolidation therapy. The neutrophil and platelet recovery time were 17 (range, 10-20) days and 16.5 (range, 12-30) days in the CA4+3 group, faster than that of 20 (16-36) days and 20 (14-36) days in the CA4+5 group (P = .006 and P = .006). The cyclophosphamide and cytarabine (CA) regimen was generally safe and had reversible adverse effects. The patients who failed to respond to the CA regimen did not benefit from a second course of other traditional induction chemotherapy either. In conclusion, the combined regimen of CTX and Ara-C represents a promising therapeutic approach to induce the first CR of newly diagnosed adult AML.
    Keywords:  acute myeloid leukemia; cyclophosphamide; cytarabine; induction chemotherapy
  19. Leukemia. 2022 Jul 22.
      Janus kinase inhibitors (JAKi) approved for myelofibrosis provide spleen and symptom improvements but do not address anemia, a negative prognostic factor. Momelotinib, an inhibitor of ACVR1/ALK2, JAK1 and JAK2, demonstrated activity against anemia, symptoms, and splenomegaly in the phase 3 SIMPLIFY trials. Here, we report mature overall survival (OS) and leukemia-free survival (LFS) from both studies, and retrospective analyses of baseline characteristics and efficacy endpoints for OS associations. Survival distributions were similar between JAKi-naïve patients randomized to momelotinib, or ruxolitinib then momelotinib, in SIMPLIFY-1 (OS HR = 1.02 [0.73, 1.43]; LFS HR = 1.08 [0.78, 1.50]). Two-year OS and LFS were 81.6% and 80.7% with momelotinib and 80.6% and 79.3% with ruxolitinib then momelotinib. In ruxolitinib-exposed patients in SIMPLIFY-2, two-year OS and LFS were 65.8% and 64.2% with momelotinib and 61.2% and 59.7% with best available therapy then momelotinib (OS HR = 0.98 [0.59, 1.62]; LFS HR = 0.97 [0.59, 1.60]). Baseline transfusion independence (TI) was associated with improved survival in both studies (SIMPLIFY-1 HR = 0.474, p = 0.0001; SIMPLIFY-2 HR = 0.226, p = 0.0005). Week 24 TI response in JAKi-naïve, momelotinib-randomized patients was associated with improved OS in univariate (HR = 0.323; p < 0.0001) and multivariate (HR = 0.311; p < 0.0001) analyses. These findings underscore the importance of achieving or maintaining TI in myelofibrosis, supporting the clinical relevance of momelotinib's pro-erythropoietic mechanism of action, and potentially informing treatment decision-making.
  20. Nat Chem Biol. 2022 Jul 21.
      Drugs that directly impede the function of driver oncogenes offer exceptional efficacy and a therapeutic window. The recently approved mutant selective small-molecule cysteine-reactive covalent inhibitor of the G12C mutant of K-Ras, sotorasib, provides a case in point. KRAS is the most frequently mutated proto-oncogene in human cancer, yet despite success targeting the G12C allele, targeted therapy for other hotspot mutants of KRAS has not been described. Here we report the discovery of small molecules that covalently target a G12S somatic mutation in K-Ras and suppress its oncogenic signaling. We show that these molecules are active in cells expressing K-Ras(G12S) but spare the wild-type protein. Our results provide a path to targeting a second somatic mutation in the oncogene KRAS by overcoming the weak nucleophilicity of an acquired serine residue. The chemistry we describe may serve as a basis for the selective targeting of other unactivated serines.
  21. Br J Haematol. 2022 Jul 22.
      Despite the success of BCR-ABL-specific tyrosine kinase inhibitors (TKIs) such as imatinib in chronic phase (CP) chronic myeloid leukaemia (CML), patients with blast phase (BP)-CML continue to have a dismal outcome with median survival of less than one year from diagnosis. Thus BP-CML remains a critical unmet clinical need in the management of CML. Our understanding of the biology of BP-CML continues to grow; genomic instability leads to acquisition of mutations which drive leukaemic progenitor cells to develop self-renewal properties, resulting in differentiation block and a poor-prognosis acute leukaemia which may be myeloid, lymphoid or bi-phenotypic. Similar advances in therapy are urgently needed to improve patient outcomes; however, this is challenging given the rarity and heterogeneity of BP-CML, leading to difficulty in designing and recruiting to prospective clinical trials. This review will explore the treatment of BP-CML, evaluating the data for TKI therapy alone, combinations with intensive chemotherapy, the role of allogeneic haemopoietic stem cell transplantation, the use of novel agents and clinical trials, as well as discussing the most appropriate methods for diagnosing BP and assessing response to therapy, and factors predicting outcome.
    Keywords:  allogeneic stem cell transplantation; blast phase chronic myeloid leukaemia; clinical trials; combination therapy; tyrosine kinase inhibitors
  22. Cancer Discov. 2022 Jul 22. OF1
      Novel germline loci were associated with the risk of clonal hematopoiesis (CH) within the UK Biobank.
  23. EJHaem. 2020 Nov;1(2): 527-536
      MLL-rearranged acute lymphoblastic leukemia (ALL) represents a highly aggressive ALL subtype, characterized by aberrant DNA methylation patterns. DNA methyltransferase inhibitors, such as decitabine have previously been demonstrated to be effective in eradicating MLL-rearranged ALL cells in vitro. Here, we assessed the in vivo anti-leukemic potential of low-dose DNA methyltransferase inhibitor decitabine using a xenograft mouse model of human MLL-rearranged ALL. Furthermore, we explored whether prolonged exposure to low-dose decitabine could chemo-sensitize MLL-rearranged ALL cells toward conventional chemotherapy as well as other known epigenetic-based and anti-neoplastic compounds. Our data reveal that decitabine prolonged survival in xenograft mice of MLL-rearranged ALL by 8.5 days (P = .0181), but eventually was insufficient to prevent leukemia out-growth, based on the examination of the MLLAF4 cell line SEM. Furthermore, we observe that prolonged pretreatment of low-dose decitabine mildly sensitized toward the conventional drugs prednisolone, vincristine, daunorubicin, asparaginase, and cytarabine in a panel of MLL-rearranged cell lines. Additionally, we assessed synergistic effects of decitabine with other epigenetic-based or anticancer drugs using high-throughput drug library screens. Validation of the top hits, including histone deacetylase inhibitor panobinostat, BCL2 inhibitor Venetoclax, MEK inhibitor pimasertib, and receptor tyrosine kinase foretinib, revealed additive and moderate synergistic effects for the combination of each drug together with decitabine in a cell line-dependent manner.
    Keywords:  DNA demethylating agent; KMT2A; MLL; acute lymphoblastic leukemia; chemo‐sensitizer; decitabine; xenograft mouse models
  24. Cell Stem Cell. 2022 Jul 12. pii: S1934-5909(22)00261-2. [Epub ahead of print]
      Hematopoietic stem cells (HSCs) mediate regeneration of the hematopoietic system following injury, such as following infection or inflammation. These challenges impair HSC function, but whether this functional impairment extends beyond the duration of inflammatory exposure is unknown. Unexpectedly, we observed an irreversible depletion of functional HSCs following challenge with inflammation or bacterial infection, with no evidence of any recovery up to 1 year afterward. HSCs from challenged mice demonstrated multiple cellular and molecular features of accelerated aging and developed clinically relevant blood and bone marrow phenotypes not normally observed in aged laboratory mice but commonly seen in elderly humans. In vivo HSC self-renewal divisions were absent or extremely rare during both challenge and recovery periods. The progressive, irreversible attrition of HSC function demonstrates that temporally discrete inflammatory events elicit a cumulative inhibitory effect on HSCs. This work positions early/mid-life inflammation as a mediator of lifelong defects in tissue maintenance and regeneration.
    Keywords:  HSCs; accelerated aging; aging; clonal hematopoiesis; hematopoietic stem cells; inflammaging; inflammation; self-renewal; stem cell exhaustion; stress hematopoiesis
  25. Mol Cell. 2022 Jul 13. pii: S1097-2765(22)00609-8. [Epub ahead of print]
      NAD+ kinases (NADKs) are metabolite kinases that phosphorylate NAD+ molecules to make NADP+, a limiting substrate for the generation of reducing power NADPH. NADK2 sustains mitochondrial NADPH production that enables proline biosynthesis and antioxidant defense. However, its molecular architecture and mechanistic regulation remain undescribed. Here, we report the crystal structure of human NADK2, revealing a substrate-driven mode of activation. We find that NADK2 presents an unexpected dimeric organization instead of the typical tetrameric assemblage observed for other NADKs. A specific extended segment (aa 325-365) is crucial for NADK2 dimerization and activity. Moreover, we characterize numerous acetylation events, including those on Lys76 and Lys304, which reside near the active site and inhibit NADK2 activity without disrupting dimerization, thereby reducing mitochondrial NADP(H) production, proline synthesis, and cell growth. These findings reveal important molecular insight into the structure and regulation of a vital enzyme in mitochondrial NADPH and proline metabolism.
    Keywords:  NAD kinases; NADK2; NADPH metabolism; crystal structure; mitochondrial metabolism; post-translational modifications; proline metabolism