bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2020‒09‒27
eighteen papers selected by
Paolo Gallipoli
Barts Cancer Institute, Queen Mary University of London

  1. Cell Metab. 2020 Sep 16. pii: S1550-4131(20)30479-4. [Epub ahead of print]
      Like normal hematopoietic stem cells, leukemic stem cells depend on their bone marrow (BM) microenvironment for survival, but the underlying mechanisms remain largely unknown. We have studied the contribution of nestin+ BM mesenchymal stem cells (BMSCs) to MLL-AF9-driven acute myeloid leukemia (AML) development and chemoresistance in vivo. Unlike bulk stroma, nestin+ BMSC numbers are not reduced in AML, but their function changes to support AML cells, at the expense of non-mutated hematopoietic stem cells (HSCs). Nestin+ cell depletion delays leukemogenesis in primary AML mice and selectively decreases AML, but not normal, cells in chimeric mice. Nestin+ BMSCs support survival and chemotherapy relapse of AML through increased oxidative phosphorylation, tricarboxylic acid (TCA) cycle activity, and glutathione (GSH)-mediated antioxidant defense. Therefore, AML cells co-opt energy sources and antioxidant defense mechanisms from BMSCs to survive chemotherapy.
    Keywords:  OXPHOS; TCA cycle; acute myeloid leukemia; antioxidant; bone marrow mesenchymal stem cells; chemotherapy; glutathione; hematopoietic stem cell niche; metabolic adaptation; microenvironment
  2. Mol Ther Oncolytics. 2020 Sep 25. 18 491-503
      Acute myeloid leukemia (AML) mesenchymal stem cells (MSCs) play an essential role in protecting leukemic cells from chemotherapeutic agents through activating a wide range of adhesion molecules and cytokines. Thus, more attention should be paid to attenuate the protection of leukemic cells by MSCs. By examining the gene expression files of MSCs from healthy donors and AML patients through high-throughput microarrays, we found that interleukin (IL)-6 was an important cytokine secreted by AML MSCs to protect leukemic cells, contributing to disease progression. Strikingly, Aurora A (AURKA) was activated by IL-6, offering a new target to interfere with leukemia. Importantly, a novel AURKA inhibitor, PW21, showed excellent AURKA kinase inhibitory activities and attenuated the interaction of leukemic cells and the microenvironment. PW21 inhibited MSC-induced cell proliferation, colony formation, and migration, and it induced cell apoptosis. Mechanically, PW21 could inhibit IL-6 secreted by MSCs. Moreover, we found that PW21 displayed a strong anti-leukemia effect on non-obese diabetic (NOD)-severe combined immunodeficiency (SCID) and murine MLL-AF9 leukemic models. PW21 significantly prolonged the survival of leukemic mice and eliminated the leukemic progenitor cells. AURKA inhibitor PW21 could provide a new approach for treatment of leukemia through blocking the protection by the leukemic microenvironment in clinical application.
    Keywords:  AML; Aurora kinase inhibitor; cell proliferation; leukemic microenvironment
  3. Future Oncol. 2020 Sep 25.
      The prognosis of patients with relapsed or refractory acute myeloid leukemia (R/R AML) is dismal with salvage standard approaches, and mutations of FMS-like tyrosine kinase 3 (FLT3) gene, occurring in around 30% of AML patients may confer even poorer outcomes. Several targeted tyrosine kinase inhibitors have been developed to improve FLT3-mutated AML patient´s survival. Gilteritinib, a highly specific second-generation class I oral FLT3 inhibitor, has demonstrated superiority to salvage chemotherapy (SC) in R/R FLT3 mutated AML based on significantly longer OS in the gilteritinib arm than in the SC arm. Gilteritinib is generally well tolerated, but some clinically relevant adverse events should be monitored, especially myelosuppression, QTc prolongation and differentiation syndrome, usually manageable (dose reductions, interruption or discontinuation) and reversible. We discuss clinical development, efficacy, safety and mechanisms of resistance of gilteritinib in the treatment of R/R patients with FLT3 mutated AML.
    Keywords:  AXL inhibitor; FLT3 inhibitors; acute myeloid leukemia; gilteritinib; refractory; relapsed
  4. Cancer Med. 2020 Sep 24.
      To explore the characteristics and prognostic significance of genetic mutations in acute myeloid leukemia (AML), we screened the gene mutation profile of 171 previously untreated AML patients using a next-generation sequencing technique targeting 127 genes with potential prognostic significance. A total of 390 genetic alterations were identified in 149 patients with a frequency of 87.1%. Younger age and high sensitivity to induction chemotherapy were associated with a lower number of mutations. NPM1 mutation was closely related to DNMT3A and FLT3-internal tandem duplication (FLT3-ITD) mutations, but mutually exclusive with ASXL1 mutation and CEBPAdouble mutation . In univariate analysis, ASXL1 or TET2 mutation predicted shorter overall survival (OS) or relapse-free survival (RFS), DNMT3A, FLT3-ITD, or RUNX1 mutation predicted a higher likelihood of remission-induction failure, whereas NRAS mutation or CEBPAdouble mutation predicted longer OS. Concurrent DNMT3A, FLT3-ITD, and NPM1 mutations predicted shorter OS. Hypomethylation agents could improve the OS in patients with DNA methylation-related mutations. According to multivariate analysis, TET2 mutation was recognized as an independent prognostic factors for RFS. In summary, our study provided a detailed pattern of gene mutations and their prognostic relevance in Chinese AML patients based on targeted next-generation sequencing screening.
    Keywords:  acute myeloid leukemia; genetic mutations; next-generation sequencing; prognosis stratification
  5. Leuk Lymphoma. 2020 Sep 19. 1-9
      We compared the outcomes of salvage chemotherapy in 146 patients with relapsed (57.5%) or refractory (42.5%) AML who received CLAG-M (51%), MEC (39%) or CLAG (10%). Minimal residual disease (MRD) was assessed by flow cytometry. Bivariate, Kaplan-Meier, and Cox regression analyses were conducted. Complete remission (CR) rate of 46% (CLAG-M 54% versus MEC/CLAG 40%, p = .045) was observed with MRD-negative CR of 33% (CLAG-M 39% versus MEC/CLAG 22%, p = .042). Median overall survival (OS) was 9.7 months; the longest OS occurred with CLAG-M (13.3, 95%CI 2.4-24.3) versus MEC (6.9, 95%CI 2.9-10.9) or CLAG (6.2, 95%CI 2.4-12.6) (p = .025). When adjusted for age, gender, relapsed/refractory AML, poor risk AML, MRD, chemotherapy and transplant, CLAG-M (HR 0.63, 95% CI 0.40-0.98, p = .042), MRD-negativity (HR 0.15, 95% CI 0.07-0.30, p < .001) and transplant (HR 0.22, 95% CI 0.13-0.39, p < .001) were associated with higher OS. Our findings confirm that CLAG-M is a reasonable salvage regimen for RR-AML followed by transplant.
    Keywords:  Acute myeloid leukemia; hematopoietic stem cell transplant; minimal residual disease; relapsed/refractory leukemia; salvage chemotherapy
  6. Exp Hematol. 2020 Sep 17. pii: S0301-472X(20)30554-3. [Epub ahead of print]
      Acute myeloid leukemia (AML) is an aggressive, disseminated hematological malignancy associated with clonal selection of aberrant self-renewing hematopoietic stem cells and progenitors and poorly differentiated myeloid blasts. The most prevalent form of leukemia in adults, AML is predominantly an aged disorder and accounts for more than 10,000 deaths per year in the United States alone. In comparison to solid tumors, AML has an overall low mutational burden; albeit more than 70% of AML patients harbor somatic mutations in genes encoding epigenetic modifiers and chromatin regulators. In the past decade discoveries highlighting the role of DNA and histone modifications in determining cellular plasticity and lineage commitment have asserted importance of epigenetic contribution to tumor cell de-differentiation and heterogeneity, tumor initiation, maintenance and relapse. Orchestration in histone methylation levels regulates pluripotency and multicellular development. Given the increasing number of reversible methylation regulators being identified, including histone methylation writer, reader and eraser enzymes, and their implication in AML pathogenesis, it has widened the scope of epigenetic reprogramming, with multiple drugs currently in various stages of pre-clinical and clinical trials. AML methylome also determines response to conventional chemotherapy, as well as AML cell interaction within tumor-immune microenvironment ecosystem. Here we summarize the latest developments focusing on molecular derangements in histone methyltransferases (HMTs) and histone demethylases (HDMs) in AML pathogenesis. AML associated HMTs and HDMs, through intricate crosstalk mechanisms maintain an altered histone methylation code conducive to disease progression. We further discuss their importance in governing response to therapy, which can be used as a biomarker for treatment efficacy. Finally we deliberate on the therapeutic potential of targeting aberrant histone methylome in AML, examine available small molecule inhibitors in combination with immunomodulating therapeutic approaches, caveats, and discuss how future studies can enable posit epigenome-based targeted therapy to become a mainstay for AML treatment.
  7. Front Immunol. 2020 ;11 1787
      Chimeric antigen receptor (CAR) T cells represent a potentially curative therapy for patients with advanced hematological cancers; however, uncertainties surround the cell-intrinsic fitness as well as the exhaustion that restrict the capacity of CAR-T. Decitabine (DAC), a DNA demethylating agent, has been demonstrated to reverse exhaustion-associated DNA-methylation programs and to improve T cell responses against tumors. Here we show that DAC significantly enhances antileukemia functions of CD123 CAR-T cells in vitro and in vivo. Additionally, it inhibits the expression of DMNT3a and DNMT1. Using the Illumina Methylation EPIC BeadChip (850 K), we identified differentially methylated regions, most of which undergo hypomethylated changes. Transcriptomic profiling revealed that CD123 CAR-T cells treated with DAC were enriched in genes associated with naive, early memory T cells, as well as non-exhausted T cells. DAC treatment also results in upregulation of immune synapse-related genes. Finally, our data further suggest that DAC works through the regulation of cellular differentiation characterized by naive and memory phenotypes. Taken together, these findings demonstrate that DAC improves the anti-leukemia properties of CD123-directed CAR-T cells, and provides a basis for rational combinatorial CAR-T-based immunotherapy for patients with acute myeloid leukemia (AML).
    Keywords:  CAR-T immunotherapy; DNA-methylation; T cell subsets; acute myeloid leukemia; decitabine; immune synapse
  8. Biol Blood Marrow Transplant. 2020 Sep 20. pii: S1083-8791(20)30584-X. [Epub ahead of print]
      The role of hematopoietic cell transplantation (HCT) in the management of newly diagnosed adult acute myeloid leukemia (AML) is reviewed and critically evaluated in this evidence-based review. An AML expert panel, consistent of both transplant and non-transplant experts was invited to develop clinically relevant frequently asked questions covering disease- and HCT-related topics. A systematic literature review was conducted to generate core recommendations that were graded based on the quality and strength of underlying evidence based on the standardized criteria established by American Society of Transplantation and Cellular Therapy Steering Committee for evidence-based reviews. Allogeneic HCT offers a survival benefit in patients with intermediate and high-risk AML and is currently a part of standard clinical care. We recommend the preferential use of myeloablative conditioning in eligible patients. A haploidentical related donor marrow graft is preferred over a cord blood unit in the absence of a fully HLA-matched donor. The evolving role of allogeneic HCT in the context of measurable residual disease monitoring and recent therapeutic advances in AML with regards to maintenance therapy after HCT are also discussed.
    Keywords:  Acute myelogenous leukemia; Acute myeloid leukemia; Adult; Bone Marrow Transplantation; Chemotherapy; Cytogenetics; Disease status; Graft versus host disease; Hematopoietic cell transplantation; Leukemia risk; Measurable residual disease; Mutations; Relapse; Therapy
  9. N Engl J Med. 2020 09 24. 383(13): 1207-1217
      BACKGROUND: No therapies for targeting KRAS mutations in cancer have been approved. The KRAS p.G12C mutation occurs in 13% of non-small-cell lung cancers (NSCLCs) and in 1 to 3% of colorectal cancers and other cancers. Sotorasib is a small molecule that selectively and irreversibly targets KRASG12C.METHODS: We conducted a phase 1 trial of sotorasib in patients with advanced solid tumors harboring the KRAS p.G12C mutation. Patients received sotorasib orally once daily. The primary end point was safety. Key secondary end points were pharmacokinetics and objective response, as assessed according to Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1.
    RESULTS: A total of 129 patients (59 with NSCLC, 42 with colorectal cancer, and 28 with other tumors) were included in dose escalation and expansion cohorts. Patients had received a median of 3 (range, 0 to 11) previous lines of anticancer therapies for metastatic disease. No dose-limiting toxic effects or treatment-related deaths were observed. A total of 73 patients (56.6%) had treatment-related adverse events; 15 patients (11.6%) had grade 3 or 4 events. In the subgroup with NSCLC, 32.2% (19 patients) had a confirmed objective response (complete or partial response) and 88.1% (52 patients) had disease control (objective response or stable disease); the median progression-free survival was 6.3 months (range, 0.0+ to 14.9 [with + indicating that the value includes patient data that were censored at data cutoff]). In the subgroup with colorectal cancer, 7.1% (3 patients) had a confirmed response, and 73.8% (31 patients) had disease control; the median progression-free survival was 4.0 months (range, 0.0+ to 11.1+). Responses were also observed in patients with pancreatic, endometrial, and appendiceal cancers and melanoma.
    CONCLUSIONS: Sotorasib showed encouraging anticancer activity in patients with heavily pretreated advanced solid tumors harboring the KRAS p.G12C mutation. Grade 3 or 4 treatment-related toxic effects occurred in 11.6% of the patients. (Funded by Amgen and others; CodeBreaK100 number, NCT03600883.).
  10. Blood Cancer Discov. 2020 Sep;1(2): 162-177
      MLL is a target of chromosomal translocations in acute leukemias with poor prognosis. The common MLL fusion partner AF9 (MLLT3) can directly bind to AF4, DOT1L, BCOR, and CBX8. To delineate the relevance of BCOR and CBX8 binding to MLL-AF9 for leukemogenesis, here we determine protein structures of AF9 complexes with CBX8 and BCOR, and show that binding of all four partners to AF9 is mutually exclusive. Using the structural analyses, we identify point mutations that selectively disrupt AF9 interactions with BCOR and CBX8. In bone marrow stem/progenitor cells expressing point mutant CBX8 or point mutant MLL-AF9, we show that disruption of direct CBX8/MLL-AF9 binding does not impact in vitro cell proliferation, whereas loss of direct BCOR/MLL-AF9 binding causes partial differentiation and increased proliferation. Strikingly, loss of MLL-AF9/BCOR binding abrogated its leukemogenic potential in a mouse model. The MLL-AF9 mutant deficient for BCOR binding reduces the expression of the EYA1 phosphatase and the protein level of c-Myc. Reduction in BCOR binding to MLL-AF9 alters a MYC-driven gene expression program, as well as altering expression of SIX-regulated genes, likely contributing to the observed reduction in the leukemia-initiating cell population.
  11. Blood Adv. 2020 Sep 22. 4(18): 4584-4592
      The surge of human genetic information, enabled by increasingly facile and economically feasible genomic technologies, has accelerated discoveries on the relationship of germline genetic variation to hematologic diseases. For example, germline variation in GATA2, encoding a vital transcriptional regulator of multilineage hematopoiesis, creates a predisposition to bone marrow failure and acute myeloid leukemia termed GATA2 deficiency syndrome. More than 300 GATA2 variants representing missense, truncating, and noncoding enhancer mutations have been documented. Although these variants can diminish GATA2 expression and/or function, the functional ramifications of many variants are unknown. Studies using genetic rescue and knockin mouse systems have established that GATA2 mutations differentially affect molecular processes in distinct target genes and within a single target cell. Considering that target genes for a transcription factor can differ in sensitivity to altered levels of the factor, and transcriptional mechanisms are often cell type specific, the context-dependent consequences of GATA2 mutations in experimental systems portend the complex phenotypes and interindividual variation of GATA2 deficiency syndrome. This review documents GATA2 human genetics and the state of efforts to traverse from physiological insights to pathogenic mechanisms.
  12. Blood Cancer Discov. 2020 Jul;1(1): 48-67
      Persistence of drug-resistant quiescent leukemic stem cells (LSC) and impaired natural killer (NK) cell immune response account for relapse of chronic myelogenous leukemia (CML). Inactivation of protein phosphatase 2A (PP2A) is essential for CML-quiescent LSC survival and NK cell antitumor activity. Here we show that MIR300 has antiproliferative and PP2A-activating functions that are dose dependently differentially induced by CCND2/CDK6 and SET inhibition, respectively. MIR300 is upregulated in CML LSCs and NK cells by bone marrow microenvironment (BMM) signals to induce quiescence and impair immune response, respectively. Conversely, BCR-ABL1 downregulates MIR300 in CML progenitors to prevent growth arrest and PP2A-mediated apoptosis. Quiescent LSCs escape apoptosis by upregulating TUG1 long noncoding RNA that uncouples and limits MIR300 function to cytostasis. Genetic and pharmacologic MIR300 modulation and/or PP2A-activating drug treatment restore NK cell activity, inhibit BMM-induced growth arrest, and selectively trigger LSC apoptosis in vitro and in patient-derived xenografts; hence, the importance of MIR300 and PP2A activity for CML development and therapy.
  13. Cancers (Basel). 2020 Sep 21. pii: E2696. [Epub ahead of print]12(9):
      Wnt/β-catenin signaling has been reported in Acute Myeloid leukemia, but little is known about its significance as a prognostic biomarker and drug target. In this study, we first evaluated the correlation between expression levels of Wnt molecules and clinical outcome. Then, we studied-in vitro and in vivo-the anti-leukemic value of combinatorial treatment between Wnt inhibitors and classic anti-leukemia drugs. Higher levels of β-catenin, Ser675-phospho-β-catenin and GSK-3α (total and Ser 9) were found in AML cells from intermediate or poor risk patients; nevertheless, patients presenting high activity of Wnt/β-catenin displayed shorter progression-free survival (PFS) according to univariate analysis. In vitro, many pharmacological inhibitors of Wnt signalling, i.e., LRP6 (Niclosamide), GSK-3 (LiCl, AR-A014418), and TCF/LEF (PNU-74654) but not Porcupine (IWP-2), significantly reduced proliferation and improved the drug sensitivity of AML cells cultured alone or in the presence of bone marrow stromal cells. In vivo, PNU-74654, Niclosamide and LiCl administration significantly reduced the bone marrow leukemic burden acting synergistically with Ara-C, thus improving mouse survival. Overall, our study demonstrates the antileukemic role of Wnt/β-catenin inhibition that may represent a potential new therapeutics strategy in AML.
    Keywords:  AML; Wnt; drug target; microenvironment
  14. Blood. 2020 Sep 21. pii: blood.2020005208. [Epub ahead of print]
      Bortezomib (BTZ) was recently evaluated in a randomized Phase 3 clinical trial which compared standard chemotherapy (cytarabine, daunorubicin, etoposide; ADE) to standard therapy with BTZ (ADEB) for de novo pediatric acute myeloid leukemia. While the study concluded that BTZ did not improve outcome overall, we examined patient subgroups benefitting from BTZ-containing chemotherapy using proteomic analyses. The proteasome inhibitor BTZ disrupts protein homeostasis and activates cytoprotective heat shock responses. We measured total heat shock factor 1 (HSF1) and phosphorylated HSF1 (HSF1-pSer326) in leukemic cells from 483 pediatric patients using Reverse Phase Protein Arrays. HSF1-pSer326 phosphorylation was significantly lower in pediatric AML compared to CD34+ non-malignant cells. We identified a strong correlation between HSF1-pSer326 expression and BTZ sensitivity. BTZ significantly improved outcome of patients with low-HSF1-pSer326 with a 5-year event-free survival of 44% (ADE) vs. 67% for low-HSF1-pSer326 treated with ADEB (P=0.019). To determine the effect of HSF1 expression on BTZ potency in vitro, cell viability with HSF1 gene variants that mimicked phosphorylated (S326A) and non-phosphorylated (S326E) HSF1-pSer326 were examined. Those with increased HSF1 phosphorylation showed clear resistance to BTZ vs. those with wild type or reduced HSF1-phosphorylation. We hypothesize that HSF1-pSer326 expression could identify patients that benefit from BTZ-containing chemotherapy.
  15. Leuk Lymphoma. 2020 Sep 24. 1-19
      Glasdegib, in combination with low-dose cytarabine (LDAC), is the first smoothened inhibitor approved for treatment of acute myeloid leukemia. Glasdegib plus LDAC is indicated for patients in whom therapy options are limited, e.g. older patients and those ineligible for intensive chemotherapy due to preexisting comorbidities. This review summarizes the recommendations of a panel of hemato-oncologists regarding the selection of patients best suited for treatment with glasdegib plus LDAC and the management during therapy with this combination. The panel considered the impact of concomitant medications and comorbidities during treatment with glasdegib plus LDAC, and discussed common adverse events (AEs) associated with glasdegib plus LDAC. Management strategies for AEs discussed by the panel included dose modifications, supportive care therapies, and prophylactic treatments. Finally, the panel highlighted the importance of patient communication and education regarding the possible AEs that may occur during treatment.
    Keywords:  Acute myeloid leukemia; adverse events; comorbidities; glasdegib; low-dose cytarabine; older patients
  16. JCO Oncol Pract. 2020 Sep 21. OP2000446
      PURPOSE: Azacitidine (AZA) is a standard of care for higher-risk myelodysplastic syndrome (MDS)/low blast-count acute myeloid leukemia (AML). Despite this, there is a paucity of data on the real-world health care resource utilization costs of AZA in this population.METHODS: We linked the Ontario AZA MDS registry-higher-risk MDS/low blast-count AML-to population-based health system administrative databases. Patients were observed for 24 months after first AZA and censored at the earliest of 90 days after last AZA, date of death, time of AML induction/stem-cell transplantation, or March 31, 2016. Costs (2015 Canadian dollars) were expressed as standardized mean and median 28-day costs. Univariable quantile regression was used to explore the association of baseline patient and disease characteristics and median cost. Multivariable quantile regression was used to explore predictors of median costs.
    RESULTS: Among 877 patients in the registry, mean standardized 28-day cost per patient was $17,638 (median, $15,272; interquartile range [IQR], $11,869-$19,580) and $13,450 (median, $11,043; IQR, $7,981-$14,882) excluding the cost of AZA. Major nondrug drivers of cost were cancer clinic visits and inpatient care (mean standardized 28-day cost, $4,631; median, $1,558; IQR, $238-$4,961). Transfusion dependence at AZA initiation (P = .001) and greater comorbid disease burden (P = .009) were independently associated with increased cost.
    CONCLUSION: Our cohort of patients with uniformly higher-risk MDS/low blast-count AML treated with AZA demonstrates substantial costs of care above and beyond the cost of AZA alone. These results provide insight into the costs of AZA in the real world with implications for resource allocation.
  17. Blood Adv. 2020 Sep 22. 4(18): 4554-4559
      The SH2-JH2 linker domain of JAK2 has been implicated in the negative regulation of JAK2 activity. In 2 patients with myeloproliferative neoplasms (MPNs), we identified and characterized the novel JAK2 mutation S523L, which occurs in a key residue in the linker region. In 1 case, acquisition of JAK2S523L was associated with thrombocytosis and bone marrow megakaryocytic hyperplasia, and there were no other somatic alterations in this patient. The second patient with JAK2S523Lmutation presented with increased hematocrit and had concurrent mutations in RUNX1 and BCORL1. Consistent with the genetic and clinical data, expression of JAK2S523L causes interleukin-3-independent growth in Ba/F3 cells transduced with the erythropoietin receptor by constitutively active Jak2/Stat5 signaling.