bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2020‒07‒05
23 papers selected by
Paolo Gallipoli
Barts Cancer Institute, Queen Mary University of London


  1. Cancers (Basel). 2020 Jun 29. pii: E1725. [Epub ahead of print]12(7):
    Serhan N, Mouchel PL, Medina P, Segala G, Mougel A, Saland E, Rives A, Lamaziere A, Despres G, Sarry JE, Larrue C, Vergez F, Largeaud L, Record M, Récher C, Silvente-Poirot S, Poirot M.
      Dendrogenin A (DDA) is a mammalian cholesterol metabolite that displays potent antitumor properties on acute myeloid leukemia (AML). DDA triggers lethal autophagy in cancer cells through a biased activation of the oxysterol receptor LXRβ, and the inhibition of a sterol isomerase. We hypothesize that DDA could potentiate the activity of an anticancer drug acting through a different molecular mechanism, and conducted in vitro and in vivo combination tests on AML cell lines and patient primary tumors. We report here results from tests combining DDA with antimetabolite cytarabine (Ara-C), one of the main drugs used for AML treatment worldwide. We demonstrated that DDA potentiated and sensitized AML cells, including primary patient samples, to Ara-C in vitro and in vivo. Mechanistic studies revealed that this sensitization was LXRβ-dependent and was due to the activation of lethal autophagy. This study demonstrates a positive in vitro and in vivo interaction between DDA and Ara-C, and supports the clinical evaluation of DDA in combination with Ara-C for the treatment of AML.
    Keywords:  Acute myeloid leukemia; Dendrogenin A; cholesterol metabolism; primary cancer cells; synergy; tumor suppressor
    DOI:  https://doi.org/10.3390/cancers12071725
  2. Mol Ther. 2020 Jun 19. pii: S1525-0016(20)30312-9. [Epub ahead of print]
    Sommer C, Cheng HY, Nguyen D, Dettling D, Yeung YA, Sutton J, Hamze M, Valton J, Smith J, Djuretic I, Chaparro-Riggers J, Sasu BJ.
      Patients with relapsed or refractory acute myeloid leukemia (AML) have a dismal prognosis and limited treatment options. Chimeric antigen receptor (CAR) T cells have achieved unprecedented clinical responses in patients with B cell leukemias and lymphomas and could prove highly efficacious in AML. However, a significant number of patients with AML may not receive treatment with an autologous product due to manufacturing failures associated with low lymphocyte counts or rapid disease progression while the therapeutic is being produced. We report the preclinical evaluation of an off-the-shelf CAR T cell therapy targeting Fms-related tyrosine kinase 3 (FLT3) for the treatment of AML. Single-chain variable fragments (scFvs) targeting various epitopes in the extracellular region of FLT3 were inserted into CAR constructs and tested for their ability to redirect T cell specificity and effector function to FLT3+ AML cells. A lead CAR, exhibiting minimal tonic signaling and robust activity in vitro and in vivo, was selected and then modified to incorporate a rituximab-responsive off-switch in cis. We found that allogeneic FLT3 CAR T cells, generated from healthy-donor T cells, eliminate primary AML blasts but are also active against mouse and human hematopoietic stem and progenitor cells, indicating risk of myelotoxicity. By employing a surrogate CAR with affinity to murine FLT3, we show that rituximab-mediated depletion of FLT3 CAR T cells after AML eradication enables bone marrow recovery without compromising leukemia remission. These results support clinical investigation of allogeneic FLT3 CAR T cells in AML and other FLT3+ hematologic malignancies.
    Keywords:  FLT3; acute myeloid leukemia; allogeneic CAR T therapy; chimeric antigen receptor
    DOI:  https://doi.org/10.1016/j.ymthe.2020.06.022
  3. Nat Med. 2020 Jun 29.
    Riether C, Pabst T, Höpner S, Bacher U, Hinterbrandner M, Banz Y, Müller R, Manz MG, Gharib WH, Francisco D, Bruggmann R, van Rompaey L, Moshir M, Delahaye T, Gandini D, Erzeel E, Hultberg A, Fung S, de Haard H, Leupin N, Ochsenbein AF.
      Acute myeloid leukemia (AML) is driven by leukemia stem cells (LSCs) that resist conventional chemotherapy and are the major cause of relapse1,2. Hypomethylating agents (HMAs) are the standard of care in the treatment of older or unfit patients with AML, but responses are modest and not durable3-5. Here we demonstrate that LSCs upregulate the tumor necrosis factor family ligand CD70 in response to HMA treatment resulting in increased CD70/CD27 signaling. Blocking CD70/CD27 signaling and targeting CD70-expressing LSCs with cusatuzumab, a human αCD70 monoclonal antibody with enhanced antibody-dependent cellular cytotoxicity activity, eliminated LSCs in vitro and in xenotransplantation experiments. Based on these preclinical results, we performed a phase 1/2 trial in previously untreated older patients with AML with a single dose of cusatuzumab monotherapy followed by a combination therapy with the HMA azacitidine (NCT03030612). We report results from the phase 1 dose escalation part of the clinical trial. Hematological responses in the 12 patients enrolled included 8 complete remission, 2 complete remission with incomplete blood count recovery and 2 partial remission with 4 patients achieving minimal residual disease negativity by flow cytometry at <10-3. Median time to response was 3.3 months. Median progression-free survival was not reached yet at the time of the data cutoff. No dose-limiting toxicities were reported and the maximum tolerated dose of cusatuzumab was not reached. Importantly, cusatuzumab treatment substantially reduced LSCs and triggered gene signatures related to myeloid differentiation and apoptosis.
    DOI:  https://doi.org/10.1038/s41591-020-0910-8
  4. Pharmacol Res. 2020 Jun 30. pii: S1043-6618(20)31366-9. [Epub ahead of print] 105058
    Losson H, Gajulapalli SR, Lernoux M, Lee JY, Mazumder A, Gérard D, Seidel C, Hahn H, Christov C, Dicato M, Kirsch G, Han BW, Schnekenburger M, Diederich M.
      Despite the discovery of tyrosine kinase inhibitors (TKIs) for the treatment of breakpoint cluster region-Abelson (BCR-ABL)+ cancer types, patients with chronic myeloid leukemia (CML) treated with TKIs develop resistance and severe adverse effects. Combination treatment, especially with a histone deacetylase (HDAC) 6 inhibitor (HDAC6i), appears to be an attractive option to prevent TKI resistance, considering the potential capacity of an HDAC6i to diminish BCR-ABL expression. We first validated the in vivo anti-cancer potential of the compound 7b by significantly reducing the tumor burden of BALB/c mice xenografted with K-562 cells, without notable organ toxicity. Here, we hypothesize that the HDAC6i compound 7b can lead to BCR-ABL downregulation in CML cells and sensitize them to TKI treatment. The results showed that combination treatment with imatinib and 7b resulted in strong synergistic caspase-dependent apoptotic cell death and drastically reduced the proportion of leukemia stem cells, whereas this treatment only moderately affected healthy cells. Ultimately, the combination significantly decreased colony formation in a semisolid methylcellulose medium and tumor mass in xenografted zebrafish compared to each compound alone. Mechanistically, the combination induced BCR-ABL ubiquitination and downregulation followed by disturbance of key proteins in downstream pathways involved in CML proliferation and survival. Taken together, our results suggest that an HDAC6i potentiates the effect of imatinib and could overcome TKI resistance in CML cells.
    Keywords:  4-hydroxybenzoic acid; Z-VAD-FMK (zVAD, PubChem CID: 5737); combination chemotherapy; etoposide (VP-16, PubChem CID: 92209272) and cisplatin (PubChem CID: 441203); imatinib (PubChem CID: 123596); imatinib resistance; leukemia stem cells; suberanilohydroxamic acid (SAHA, PubChem CID: 5311); synergistic cytotoxic effect; tubacin (PubChem CID: 6675804); tyrosine kinase inhibitor
    DOI:  https://doi.org/10.1016/j.phrs.2020.105058
  5. Blood Adv. 2020 Jul 14. 4(13): 3000-3010
    Habbel J, Arnold L, Chen Y, Möllmann M, Bruderek K, Brandau S, Dührsen U, Hanoun M.
      Acute myeloid leukemia (AML) is characterized by a high relapse rate and dismal long-term overall survival which is related to persistence of leukemia-initiating cells in their niche. Different animal models of myeloid malignancies reveal how neoplastic cells alter the structural and functional characteristics of the hematopoietic stem cell niche to reinforce malignancy. Understanding and disruption of the microenvironmental interactions with AML cells are a vital need. Malignant niches frequently go along with inflammatory responses, but their impact on cancerogenesis often remains unexplored. Here, we uncovered an aberrant production of inflammatory cytokines in untreated AML bone marrow that was proved to promote the proliferation of leukemia cells. This inflammatory response induced an activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway in AML blasts as well as bone marrow stromal cells that also fostered leukemia proliferation. Inhibition of JAK/STAT signaling using the selective JAK1/2 inhibitor ruxolitinib resulted in significant antileukemic activity in AML in vitro which is mediated through both cell-autonomous and microenvironment-mediated mechanisms. However, in a xenograft transplantation model, monotherapy with ruxolitinib did not achieve substantial antileukemic activity, possibly suggesting a complementary function of JAK1/2 inhibition in AML.
    DOI:  https://doi.org/10.1182/bloodadvances.2019001292
  6. Blood. 2020 Jun 29. pii: blood.2020006374. [Epub ahead of print]
    Bulaeva E, Pellacani D, Nakamichi N, Hammond CA, Beer P, Lorzadeh A, Moksa M, Carles A, Bilenky M, Lefort S, Shu JY, Wilhelm B, Weng A, Hirst M, Eaves CJ.
      Hematopoietic clones with leukemogenic mutations arise in healthy people as they age, but progression to acute myeloid leukemia (AML) is rare. Recent evidence suggests that the microenvironment may play an important role in modulating human AML population dynamics. To investigate this concept further, we examined the combined and separate effects of an oncogene (c-MYC) and exposure to IL3, GM-CSF and SCF on the experimental genesis of a human AML in xenografted immunodeficient mice. Initial experiments showed that normal human CD34+ blood cells transduced with a lentiviral MYC vector and then transplanted into immunodeficient mice produced a hierarchically organized, rapidly fatal and serially transplantable blast population, phenotypically and transcriptionally similar to human AML cells, but only in mice producing IL3, GM-CSF and SCF transgenically, or in regular mice in which the cells were exposed to IL3 or GM-CSF delivered using a co-transduction strategy. In their absence, the MYC+ human cells produced a normal repertoire of lymphoid and myeloid progeny in transplanted mice for many months but, upon transfer to secondary mice producing the human cytokines, the MYC+ cells rapidly generated AML. Indistinguishable diseases were also obtained efficiently from both primitive (CD34+CD38-) and late (GMPs) cells. These findings underscore the critical role that these cytokines can play in activating a malignant state in normally differentiating human hematopoietic cells in which MYC expression has been deregulated. They also introduce a robust experimental model of human leukemogenesis to further elucidate key mechanisms involved and test strategies to suppress them.
    DOI:  https://doi.org/10.1182/blood.2020006374
  7. Stem Cells Transl Med. 2020 Jun 29.
    Li X, Ma X, Chen Y, Peng D, Wang H, Chen S, Xiao Y, Li L, Zhou H, Cheng F, Gao Y, Chang J, Cheng T, Liu L.
      The stemness of ex vivo expanded hematopoietic stem cells (HSCs) is usually compromised by current methods. To explore the failure mechanism of stemness maintenance of human HSCs, which were expanded from human umbilical cord blood (hUCB) CD34+ cells, by differentiation inhibitor Stem Regenin 1 (SR1), an antagonist of aryl hydrocarbon receptor, we investigated the activity of p38 mitogen-activated protein kinase α (p38 MAPKα, p38α) and mammalian target of rapamycin complex 1 (mTORC1), and their effect on SR1-expanded hUCB CD34+ cells. Our results showed that cellular senescence occurred in the SR1-expanded hUCB CD34+ cells in which p38α and mTORC1 were successively activated. Furthermore, their coinhibition resulted in a further decrease in hUCB CD34+ cell senescence without an effect on apoptosis, promoted the maintenance of expanded phenotypic HSCs without differentiation inhibition, increased the hematopoietic reconstitution ability of multiple lineages, and potentiated the long-term self-renewal capability of HSCs from SR1-expanded hUCB CD34+ cells in NOD/Shi-scid/IL-2Rγnull mice. Our mechanistic study revealed that senescence inhibition by our strategy was mainly attributed to downregulation of the splicesome, proteasome formation, and pyrimidine metabolism signaling pathways. These results suggest that coinhibition of activated p38α and mTORC1 potentiates stemness maintenance of HSCs from SR1-expanded hUCB CD34+ cells via senescence inhibition. Thus, we established a new strategy to maintain the stemness of ex vivo differentiation inhibitor-expanded human HSCs via coinhibition of multiple independent senescence initiating signal pathways. This senescence inhibition-induced stemness maintenance of ex vivo expanded HSCs could also have an important role in other HSC expansion systems.
    Keywords:  HSC stemness maintenance; Stem Regenin 1; cellular senescence; ex vivo expansion; human cord blood CD34+ cells; mammalian target of rapamycin complex 1; p38 mitogen-activated protein kinase α
    DOI:  https://doi.org/10.1002/sctm.20-0129
  8. Leukemia. 2020 Jun 29.
    Kuendgen A, Nomdedeu M, Tuechler H, Garcia-Manero G, Komrokji RS, Sekeres MA, Della Porta MG, Cazzola M, DeZern AE, Roboz GJ, Steensma DP, Van de Loosdrecht AA, Schlenk RF, Grau J, Calvo X, Blum S, Pereira A, Valent P, Costa D, Giagounidis A, Xicoy B, Döhner H, Platzbecker U, Pedro C, Lübbert M, Oiartzabal I, Díez-Campelo M, Cedena MT, Machherndl-Spandl S, López-Pavía M, Baldus CD, Martinez-de-Sola M, Stauder R, Merchan B, List A, Ganster C, Schroeder T, Voso MT, Pfeilstöcker M, Sill H, Hildebrandt B, Esteve J, Nomdedeu B, Cobo F, Haas R, Sole F, Germing U, Greenberg PL, Haase D, Sanz G.
      In the current World Health Organization (WHO)-classification, therapy-related myelodysplastic syndromes (t-MDS) are categorized together with therapy-related acute myeloid leukemia (AML) and t-myelodysplastic/myeloproliferative neoplasms into one subgroup independent of morphologic or prognostic features. Analyzing data of 2087 t-MDS patients from different international MDS groups to evaluate classification and prognostication tools we found that applying the WHO classification for p-MDS successfully predicts time to transformation and survival (both p < 0.001). The results regarding carefully reviewed cytogenetic data, classifications, and prognostic scores confirmed that t-MDS are similarly heterogeneous as p-MDS and therefore deserve the same careful differentiation regarding risk. As reference, these results were compared with 4593 primary MDS (p-MDS) patients represented in the International Working Group for Prognosis in MDS database (IWG-PM). Although a less favorable clinical outcome occurred in each t-MDS subset compared with p-MDS subgroups, FAB and WHO-classification, IPSS-R, and WPSS-R separated t-MDS patients into differing risk groups effectively, indicating that all established risk factors for p-MDS maintained relevance in t-MDS, with cytogenetic features having enhanced predictive power. These data strongly argue to classify t-MDS as a separate entity distinct from other WHO-classified t-myeloid neoplasms, which would enhance treatment decisions and facilitate the inclusion of t-MDS patients into clinical studies.
    DOI:  https://doi.org/10.1038/s41375-020-0917-7
  9. Drug Des Devel Ther. 2020 ;14 2413-2422
    Wu H, Cheng X, Huang F, Shao G, Meng Y, Wang L, Wang T, Jia X, Yang T, Wang X, Fu C.
      Purpose: Acute myeloid leukemia (AML) is a complex malignancy characterized by the clonal expansion of immature myeloid precursors. The standard treatment for newly diagnosed AML is chemotherapy consisting of cytosine arabinoside (Ara-C) and anthracyclines with disappointing clinical outcomes and severe adverse effects, such as symptomatic bradycardia, neurotoxicity. Thus, it is promising to treat AML through combination drug therapy to reduce the adverse effects of chemotherapeutics. In our recent published PNAS paper, we reported that NK-1R antagonists, both Aprepitant and SR140333, induce apoptosis of myeloid leukemia cells by inducing oxidative stress through mitochondrial calcium overload. We, therefore, tested the hypothesis of the combination Ara-C with NK-1R antagonist could enhance the efficacy of Ara-C.Methods: MTT assay was employed to detect the cell proliferation. Flow cytometry was applied to detect the cell cycle and necrosis. PI uptake and LDH release assay were used to detect the disintegration of the plasma membrane. Xenograft model was constructed to explore the effect of combination Ara-C with Aprepitant in vivo.
    Results: Our results showed that Aprepitant sensitizes HL60 cells to the cytotoxic effects of Ara-C more than 5-fold by enhancing G0/G1 cell cycle arrest and necrosis in vitro. Furthermore, Nec-1, a specific inhibitor of necroptosis, could recover the cell proliferative viability significantly. Attractively, once every 2-days regimen of Ara-C (5 mg/kg) and Aprepitant (10 mg/kg) via in situ injection dramatically reduced the tumor volume from 2175.0 ± 341.9 mm3 in the vehicle group to 828.4 ± 232.4 mm3 in the combination group without obvious toxicity in human myeloid leukemia xenograft mice.
    Conclusion: Taken together, reduced dose of Ara-C combination with moderate Aprepitant provides more effective therapeutical methods for AML treatment in vitro and in vivo with the elimination of the toxicity of Ara-C, which may pay new avenue for the usage of the routine chemotherapy drug Ara-C with low dose to enhance efficacy and reduce toxicity in clinical practice.
    Keywords:  acute myeloid leukemia; combined chemotherapy; cytosine arabinoside; neurokinin receptor antagonist
    DOI:  https://doi.org/10.2147/DDDT.S244648
  10. Nat Commun. 2020 Jul 03. 11(1): 3339
    Zhang Y, Guo Y, Gough SM, Zhang J, Vann KR, Li K, Cai L, Shi X, Aplan PD, Wang GG, Kutateladze TG.
      Chromosomal NUP98-PHF23 translocation is associated with an aggressive form of acute myeloid leukemia (AML) and poor survival rate. Here, we report the molecular mechanisms by which NUP98-PHF23 recognizes the histone mark H3K4me3 and is inhibited by small molecule compounds, including disulfiram that directly targets the PHD finger of PHF23 (PHF23PHD). Our data support a critical role for the PHD fingers of NUP98-PHF23, and related NUP98-KDM5A and NUP98-BPTF fusions in driving leukemogenesis, and demonstrate that blocking this interaction in NUP98-PHF23 expressing AML cells leads to cell death through necrotic and late apoptosis pathways. An overlap of NUP98-KDM5A oncoprotein binding sites and H3K4me3-positive loci at the Hoxa/b gene clusters and Meis1 in ChIP-seq, together with NMR analysis of the H3K4me3-binding sites of the PHD fingers from PHF23, KDM5A and BPTF, suggests a common PHD finger-dependent mechanism that promotes leukemogenesis by this type of NUP98 fusions. Our findings highlight the direct correlation between the abilities of NUP98-PHD finger fusion chimeras to associate with H3K4me3-enriched chromatin and leukemic transformation.
    DOI:  https://doi.org/10.1038/s41467-020-17098-4
  11. Cell Stem Cell. 2020 Jul 02. pii: S1934-5909(20)30276-9. [Epub ahead of print]27(1): 3-5
    Cheng Y, Luo H, Kharas MG.
      In this issue of Cell Stem Cell, Shen et al. (2020) and Wang et al. (2020) independently identify the essential function of m6A demethylase ALKBH5 in maintaining myeloid leukemia stem cells. These studies expand the regulators of the epitranscriptome that are required for acute myeloid leukemia (AML) development.
    DOI:  https://doi.org/10.1016/j.stem.2020.06.009
  12. Cancer Treat Rev. 2020 May 16. pii: S0305-7372(20)30064-5. [Epub ahead of print]88 102026
    Boudny M, Trbusek M.
      Progress in cancer therapy changed the outcome of many patients and moved therapy from chemotherapy agents to targeted drugs. Targeted drugs already changed the clinical practice in treatment of leukemias, such as imatinib (BCR/ABL inhibitor) in chronic myeloid leukemia (CML) and acute lymphoblastic leukemia (ALL), ibrutinib (Bruton's tyrosine kinase inhibitor) in chronic lymphocytic leukemia (CLL), venetoclax (BCL2 inhibitor) in CLL and acute myeloid leukemia (AML) or midostaurin (FLT3 inhibitor) in AML. In this review, we focused on DNA damage response (DDR) inhibition, specifically on inhibition of ATR-CHK1 pathway. Cancer cells harbor often defects in different DDR pathways, which render them vulnerable to DDR inhibition. Some DDR inhibitors showed interesting single-agent activity even in the absence of cytotoxic drug especially in cancers with underlying defects in DDR or DNA replication. Almost no mutations were found in ATR and CHEK1 genes in leukemia patients. Together with the fact that ATR-CHK1 pathway is essential for cell development and survival of leukemia cells, it represents a promising therapeutic target for treatment of leukemia. ATR-CHK1 inhibition showed excellent results in preclinical testing in acute and chronic leukemias. However, results in clinical trials are so far insufficient. Therefore, the ongoing and future clinical trials will decide on the success of ATR/CHK1 inhibitors in clinical practice of leukemia treatment.
    Keywords:  ATR; CHK1; DDR; Inhibition; Leukemia
    DOI:  https://doi.org/10.1016/j.ctrv.2020.102026
  13. Blood Adv. 2020 Jul 14. 4(13): 3034-3040
    Rousselot P, Loiseau C, Delord M, Cayuela JM, Spentchian M.
      Treatment-free remission (TFR) is an opportunity for patients with chronic myeloid leukemia (CML). Reported cumulative incidence curves of molecular recurrence (MRec) arbor a 2-phase shape with mainly early events, but also some late events (late MRec [LMRec]). Having discontinued our first patient in 2004, we have access to a prolonged follow-up, enabling us to characterize these late events. Over 15 years, 128 patients from our institution were registered in the Stop Imatinib (STIM; A Study for Tyrosine Kinase Inhibitors Discontinuation [A-STIM]) trial. MRec was defined by the loss of major molecular response (BCR-ABL1IS >0.1%). At the first TFR attempt, patients had been taking a tyrosine kinase inhibitor for a median of 7.1 years and in BCR-ABL1IS ≤0.01% (MR4) for a median of 4 years. The median follow-up of patients in TFR was 6.5 years. The TFR rate was estimated to be 45.6% after 7 years. For 9/65 (14%) patients experiencing MRec, recurrence occurred after 2 years in TFR (median, 3.6 years). The residual rate of MRec after 2 years was estimated to be 18%. The probability of remaining in TFR was 65.4% for patients having experienced fluctuations of their minimal residual disease (MRD) (at least 2 consecutive measurements BCR-ABL1IS >0.0032% or loss of MR4), whereas it was 100% for those with stable MRD (P = .003). After 2 years in TFR, we observed an 18% residual rate of LMRec. These late events represent 14% of all MRec and occur in patients with fluctuating MRD measurements. A long-term molecular follow-up therefore remains mandatory for CML patients in TFR. The A-STIM study was registered at www.clinicaltrials.gov as #NCT02897245.
    DOI:  https://doi.org/10.1182/bloodadvances.2020001772
  14. Cancer Res. 2020 Jun 30. pii: canres.0024.2020. [Epub ahead of print]
    Tohumeken S, Baur R, Böttcher M, Stoll A, Loschinski R, Panagiotidis K, Braun M, Saul D, Völkl S, Baur AS, Bruns H, Mackensen A, Jitschin R, Mougiakakos D.
      Acute myeloid leukemia (AML) represents the most common acute leukemia amongst adults. Despite recent progress in diagnosis and treatment, long-term outcome remains unsatisfactory. The success of allogeneic stem cell transplantation underscores the immunoresponsive nature of AML creating the basis for further exploiting immunotherapies. However, emerging evidence suggests that AML, similar to other malignant entities, employs a variety of mechanisms to evade immunosurveillance. In light of this, T-cell-inhibitory myeloid-derived suppressor cells (MDSCs) are gaining interest as key facilitators of immunoescape. Accumulation of CD14+HLA-DRlow monocytic MDSCs has been described in newly diagnosed AML patients, and deciphering the underlying mechanisms could help to improve anti-AML immunity. Here we report that conventional monocytes readily take up AML-derived extracellular vesicles and subsequently undergo MDSC differentiation. They acquired an CD14+HLA-DRlow phenotype, expressed the immunomodulatory indoleamine-2,3-dioxygenase, and upregulated expression of genes characteristic for MDSCs, such as S100A8/9 and cEBPbeta. The Akt/mTOR pathway played a critical role in the AML extracellular vesicles-induced phenotypical and functional transition of monocytes. Generated MDSCs displayed a glycolytic switch which rendered them more susceptible towards glycolytic inhibitors. Furthermore, palmitoylated proteins on the AML-EV surface activated toll-like receptor 2 (TLR2) as the initiating event of Akt/mTOR-dependent induction of MDSC. Therefore, targeting protein palmitoylation in AML blasts could block MDSC accumulation to improve immune responses.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-20-0024
  15. Haematologica. 2020 Jul 02. pii: haematol.2019.231944. [Epub ahead of print]
    Gutjahr JC, Bayer E, Yu X, Laufer JM, Höpner JP, Tesanovic S, Härzschel A, Auer G, Rieß T, Salmhofer A, Szenes E, Haslauer T, Durand-Onayli V, Ramspacher A, Pennisi SP, Artinger M, Zaborsky N, Chigaev A, Aberger F, Neureiter D, Pleyer L, Legler DF, Orian-Rousseau V, Greil R, Hartmann TN.
      Adhesive properties of leukemia cells shape the degree of organ infiltration and the extent of leukocytosis. CD44 and the integrin VLA-4, a CD49d/CD29 heterodimer, are important factors of progenitor cell adhesion in bone marrow (BM). Here, we report their cooperation in acute myeloid leukemia (AML) by a novel non-classical CD44-mediated way of inside-out VLA-4 activation. In primary AML BM samples from patients and the OCI-AML3 cell line, CD44 engagement by hyaluronan induced inside-out activation of VLA-4 resulting in enhanced leukemia cell adhesion on VCAM-1. This was independent from VLA-4 affinity regulation but based on ligand-induced integrin clustering on the cell surface. CD44-induced VLA-4 activation could be inhibited by the Src family kinase inhibitor PP2 and the multikinase inhibitor midostaurin. In further consequence, the increased adhesion on VCAM-1 allowed AML cells to strongly bind stromal cells. Thereby VLA-4/VCAM-1 interaction promoted activation of Akt, MAPK, NF-kB and mTOR signaling and decreased AML cell apoptosis. Collectively, our investigations provide a mechanistic description of an unusual CD44 function in regulating VLA-4 avidity in AML, supporting AML cell retention in the supportive BM microenvironment.
    Keywords:  Acute Myeloid Leukemia; Bone Marrow Microenvironment; CD44; CD49d/CD29 integrin; inside-out signaling
    DOI:  https://doi.org/10.3324/haematol.2019.231944
  16. Nat Genet. 2020 Jun 29.
    Meir Z, Mukamel Z, Chomsky E, Lifshitz A, Tanay A.
      Propagation of clonal regulatory programs contributes to cancer development. It is poorly understood how epigenetic mechanisms interact with genetic drivers to shape this process. Here, we combine single-cell analysis of transcription and DNA methylation with a Luria-Delbrück experimental design to demonstrate the existence of clonally stable epigenetic memory in multiple types of cancer cells. Longitudinal transcriptional and genetic analysis of clonal colon cancer cell populations reveals a slowly drifting spectrum of epithelial-to-mesenchymal transcriptional identities that is seemingly independent of genetic variation. DNA methylation landscapes correlate with these identities but also reflect an independent clock-like methylation loss process. Methylation variation can be explained as an effect of global trans-acting factors in most cases. However, for a specific class of promoters-in particular, cancer-testis antigens-de-repression is correlated with and probably driven by loss of methylation in cis. This study indicates how genetic sub-clonal structure in cancer cells can be diversified by epigenetic memory.
    DOI:  https://doi.org/10.1038/s41588-020-0645-y
  17. Am J Hematol. 2020 Jun 29.
    Daga S, Rosenberger A, Kashofer K, Heitzer E, Quehenberger F, Halbwedl I, Graf R, Krisper N, Prietl B, Höfler G, Reinisch A, Zebisch A, Sill H, Wölfler A.
      Persistent measurable residual disease (MRD) is an increasingly important prognostic marker in acute myeloid leukemia (AML). Currently, MRD is determined by multi-parameter flow cytometry (MFC) or PCR-based methods detecting leukemia-specific fusion transcripts and mutations. However, while MFC is highly operator-dependent and difficult to standardize, PCR-based methods are only available for a minority of AML patients. Here we describe a novel, highly sensitive and broadly applicable method for MRD detection by combining MFC-based leukemic cell enrichment using an optimized combinatorial antibody panel targeting CLL-1, TIM-3, CD123 and CD117 followed by mutational analysis of recurrently mutated genes in AML. In dilution experiments this method showed a sensitivity of 10-4 to 10-5 for residual disease detection. In prospectively collected remission samples this marker combination allowed for a median 67-fold cell enrichment with sufficient DNA quality for mutational analysis using next generation sequencing (NGS) or digital PCR in 39 out of 41 patients. Twenty-one samples (53.8%) tested MRD positive, whereas 18 (46.2%) were negative. With a median follow-up of 559 days 71.4% of MRD positive (15/21) and 27.8% (5/18) of MRD negative patients relapsed (p=0.0065). The cumulative incidence of relapse (CIR) was higher for MRD positive patients (5-year CIR: 90.5% vs 28%, p<0.001). In multivariate analysis, MRD positivity was a prominent factor for CIR. Thus, MFC-based leukemic cell enrichment using antibodies against CLL-1, TIM-3, CD123 and CD117 followed by mutational analysis allows high sensitive MRD detection and is informative on relapse risk in the majority of AML patients. This article is protected by copyright. All rights reserved.
    DOI:  https://doi.org/10.1002/ajh.25918
  18. Cancer Discov. 2020 Jun 30. pii: CD-19-1469. [Epub ahead of print]
    Cai SF, Chu SH, Goldberg AD, Parvin S, Koche RP, Glass JL, Stein EM, Tallman MS, Sen F, Famulare CA, Cusan M, Huang CH, Chen CW, Zou L, Cordner KB, DelGaudio NL, Durani V, Kini M, Rex M, Tian HS, Zuber J, Baslan T, Lowe SW, Rienhoff HY, Letai A, Levine RL, Armstrong SA.
      The cell of origin of oncogenic transformation is a determinant of therapeutic sensitivity, but the mechanisms governing cell-of-origin-driven differences in therapeutic response have not been delineated. Leukemias initiating in hematopoietic stem cells (HSC) are less sensitive to chemotherapy and highly express the transcription factor Evi1 compared to leukemias derived from myeloid progenitors. Here, we compared leukemias initiated in either HSCs or myeloid progenitors to reveal a novel function for Evi1 in modulating p53 protein abundance and activity. HSC-derived leukemias exhibit decreased apoptotic priming, attenuated p53 transcriptional output, and resistance to lysine-specific demethylase 1 inhibitors in addition to classical genotoxic stresses. p53 loss-of-function in Evi1-low progenitor-derived leukemias induces resistance to LSD1 inhibition, and Evi1-high leukemias are sensitized to LSD1 inhibition by venetoclax. Our findings demonstrate a role for EVI1 in p53 wild-type cancers in reducing p53 function and provide a strategy to circumvent drug resistance in chemoresistant EVI1-high AML.
    DOI:  https://doi.org/10.1158/2159-8290.CD-19-1469
  19. Adv Cancer Res. 2020 ;pii: S0065-230X(20)30034-8. [Epub ahead of print]147 1-57
    Ghosh S, Marrocco I, Yarden Y.
      Growth factors and their receptor tyrosine kinases (RTKs), a group of transmembrane molecules harboring cytoplasm-facing tyrosine-specific kinase functions, play essential roles in migration of multipotent cell populations and rapid proliferation of stem cells' descendants, transit amplifying cells, during embryogenesis and tissue repair. These intrinsic functions are aberrantly harnessed when cancer cells undergo intertwined phases of cell migration and proliferation during cancer progression. For example, by means of clonal expansion growth factors fixate the rarely occurring driver mutations, which initiate tumors. Likewise, autocrine and stromal growth factors propel angiogenesis and penetration into the newly sprouted vessels, which enable seeding micro-metastases at distant organs. We review genetic and other mechanisms that preempt ligand-mediated activation of RTKs, thereby supporting sustained cancer progression. The widespread occurrence of aberrant RTKs and downstream signaling pathways in cancer, identifies molecular targets suitable for pharmacological intervention. We list all clinically approved cancer drugs that specifically intercept oncogenic RTKs. These are mainly tyrosine kinase inhibitors and monoclonal antibodies, which can inhibit cancer but inevitably become progressively less effective due to adaptive rewiring processes or emergence of new mutations, processes we overview. Similarly important are patient treatments making use of radiation, chemotherapeutic agents and immune checkpoint inhibitors. The many interfaces linking RTK-targeted therapies and these systemic or local regimens are described in details because of the great promise offered by combining pharmacological modalities.
    Keywords:  Cancer therapy; Chemotherapy; EMT; Growth factor; Metastasis; RTK
    DOI:  https://doi.org/10.1016/bs.acr.2020.04.002
  20. Leukemia. 2020 Jun 29.
    Armand P, Lesokhin A, Borrello I, Timmerman J, Gutierrez M, Zhu L, Popa McKiver M, Ansell SM.
      Simultaneously targeting other pathways could increase the activity of PD-1 blockade in lymphoid malignancies not sensitive to single-agent blockade. We explored the safety and efficacy of combined PD-1 and CTLA-4 or KIR blockade in patients with relapsed/refractory (R/R) lymphoid malignancies. This phase 1b trial enrolled adult patients with R/R classical Hodgkin lymphoma (cHL), non-Hodgkin lymphoma (NHL), or multiple myeloma (MM). Patients received nivolumab plus ipilimumab (nivo/ipi) or lirilumab (nivo/liri) until complete response (CR), progression, or unacceptable toxicity. The primary endpoint was safety and tolerability, while secondary endpoints included overall (ORR) and CR rates (CRR), progression-free and overall survival. Sixty-five patients were treated with nivo/ipi, and 72 with nivo/liri. Twenty-nine percent of patients experienced grade 3-4 treatment-related adverse events with nivo/ipi, and 15% with nivo/liri. In cHL, ORR was 74% for nivo/ipi and 76% for nivo/liri, CRRs were 23% and 24%, respectively. In B-NHL and T-NHL, ORR range was 9-22% and CRR was 0-6%. No patient with MM had an objective response. While both combinations were active in cHL, the toxicity of nivo/ipi was higher than expected from nivolumab alone. These data suggest no meaningful improvement in the efficacy of the combinations over single-agent nivolumab in the diseases studied.
    DOI:  https://doi.org/10.1038/s41375-020-0939-1
  21. Mol Genet Genomic Med. 2020 Jul 02. e1365
    Wang H, Lin SY, Hu FF, Guo AY, Hu H.
      BACKGROUND: The cytogenetic aberrations were considered as markers for diagnosis and prognosis in acute myeloid leukemia (AML), while the expression and regulation under different cytogenetic groups remain to be fully elucidated.METHODS: In this paper, for favorable, poor, and cytogenetically normal groups of AML patients, we performed comprehensive bioinformatics analyses including identifying differentially expressed genes (DEGs) and microRNAs (miRNAs) among them, functional enrichment and regulatory networks.
    RESULTS: We found that DEGs were enriched in membrane-related processes. Eleven genes and two miRNAs were significantly differentially expressed among these three AML groups. In survival analysis, membrane-related genes and several miRNAs were significant on prognostic outcome. Notably, six HOXA and three HOXB genes were significantly in low expression and high methylation in AML with favorable cytogenetics. Meanwhile, the miRNA-HOX gene co-regulatory networks revealed that HOXA5 was a hub node and regulated an AML oncogene SPARC.
    CONCLUSION: Our work may provide novel insights to the molecular characteristics and classification between AML with different cytogenetics.
    Keywords:  HOX gene; acute myeloid leukemia; cytogenetics aberration; gene co-regulatory network; membrane protein
    DOI:  https://doi.org/10.1002/mgg3.1365
  22. Nat Commun. 2020 Jul 03. 11(1): 3326
    Ishak Gabra MB, Yang Y, Li H, Senapati P, Hanse EA, Lowman XH, Tran TQ, Zhang L, Doan LT, Xu X, Schones DE, Fruman DA, Kong M.
      Tumour cells adapt to nutrient deprivation in vivo, yet strategies targeting the nutrient poor microenvironment remain unexplored. In melanoma, tumour cells often experience low glutamine levels, which promote cell dedifferentiation. Here, we show that dietary glutamine supplementation significantly inhibits melanoma tumour growth, prolongs survival in a transgenic melanoma mouse model, and increases sensitivity to a BRAF inhibitor. Metabolomic analysis reveals that dietary uptake of glutamine effectively increases the concentration of glutamine in tumours and its downstream metabolite, αKG, without increasing biosynthetic intermediates necessary for cell proliferation. Mechanistically, we find that glutamine supplementation uniformly alters the transcriptome in tumours. Our data further demonstrate that increase in intra-tumoural αKG concentration drives hypomethylation of H3K4me3, thereby suppressing epigenetically-activated oncogenic pathways in melanoma. Therefore, our findings provide evidence that glutamine supplementation can serve as a potential dietary intervention to block melanoma tumour growth and sensitize tumours to targeted therapy via epigenetic reprogramming.
    DOI:  https://doi.org/10.1038/s41467-020-17181-w