Asxl1 loss cooperates with oncogenic Nras in mice to reprogram the immune microenvironment and drive leukemic transformation.

Mutations in chromatin regulator ASXL1 are frequently identified in myeloid malignancies, in particular ∼40% of patients with chronic myelomonocytic leukemia (CMML). ASXL1 mutations are associated with poor prognosis in CMML and significantly co-occur with NRAS mutations. Here, we show that concurrent ASXL1 and NRAS mutations defined a population of CMML patients who had shorter leukemia-free survival than those with ASXL1 mutation only. Corroborating this human data, Asxl1-/- accelerated CMML progression and promoted CMML transformation to acute myeloid leukemia (AML) in NrasG12D/+ mice. NrasG12D/+;Asxl1-/- (NA) leukemia cells displayed hyperactivation of MEK/ERK signaling, increased global levels of H3K27ac, upregulation of Flt3. Moreover, we find that NA-AML cells overexpressed all the major inhibitory immune checkpoint ligands: programmed death-ligand 1 (PD-L1)/PD-L2, CD155, and CD80/CD86. Among them, overexpression of PD-L1 and CD86 correlated with upregulation of AP-1 transcription factors (TFs) in NA-AML cells. An AP-1 inhibitor or short hairpin RNAs against AP-1 TF Jun decreased PD-L1 and CD86 expression in NA-AML cells. Once NA-AML cells were transplanted into syngeneic recipients, NA-derived T cells were not detectable. Host-derived wild-type T cells overexpressed programmed cell death protein 1 (PD-1) and T-cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT) receptors, leading to a predominant exhausted T-cell phenotype. Combined inhibition of MEK and BET resulted in downregulation of Flt3 and AP-1 expression, partial restoration of the immune microenvironment, enhancement of CD8 T-cell cytotoxicity, and prolonged survival in NA-AML mice. Our study suggests that combined targeted therapy and immunotherapy may be beneficial for treating secondary AML with concurrent ASXL1 and NRAS mutations.

Chronic myelomonocytic leukaemia stem cell transcriptomes anticipate disease morphology and outcome.

BACKGROUND: Chronic myelomonocytic leukaemia (CMML) is a clinically heterogeneous stem cell malignancy with overlapping features of myelodysplasia and myeloproliferation. Over 90% of patients carry mutations in epigenetic and/or splicing genes, typically detectable in the Lin-CD34+CD38- immunophenotypic stem cell compartment in which the leukaemia-initiating cells reside. Transcriptional dysregulation at the stem cell level is likely fundamental to disease onset and progression. METHODS: We performed single-cell RNA sequencing on 6826 Lin-CD34+CD38-stem cells from CMML patients and healthy controls using the droplet-based, ultra-high-throughput 10x platform. FINDINGS: We found substantial inter- and intra-patient heterogeneity, with CMML stem cells displaying distinctive transcriptional programs. Compared with normal controls, CMML stem cells exhibited transcriptomes characterized by increased expression of myeloid-lineage and cell cycle genes, and lower expression of genes selectively expressed by normal haematopoietic stem cells. Neutrophil-primed progenitor genes and a MYC transcription factor regulome were prominent in stem cells from CMML-1 patients, whereas CMML-2 stem cells exhibited strong expression of interferon-regulatory factor regulomes, including those associated with IRF1, IRF7 and IRF8. CMML-1 and CMML-2 stem cells (stages distinguished by proportion of downstream blasts and promonocytes) differed substantially in both transcriptome and pseudotime, indicating fundamentally different biology underpinning these disease states. Gene expression and pathway analyses highlighted potentially tractable therapeutic vulnerabilities for downstream investigation. Importantly, CMML patients harboured variably-sized subpopulations of transcriptionally normal stem cells, indicating a potential reservoir to restore functional haematopoiesis. INTERPRETATION: Our findings provide novel insights into the CMML stem cell compartment, revealing an unexpected degree of heterogeneity and demonstrating that CMML stem cell transcriptomes anticipate disease morphology, and therefore outcome. FUNDING: Project funding was supported by Oglesby Charitable Trust, Cancer Research UK, Blood Cancer UK, and UK Medical Research Council.

Autoimmune disease in CMML-the chicken or the egg?

Chronic myelomonocytic leukemia (CMML) is a clonal disorder that is associated with a wide range of systemic inflammatory and autoimmune diseases (SIADs). Approximately 20% of patients with CMML will have an associated SIAD and recognizing this association is critical to the evaluation, prognostication and management of patients with CMML. In this paper, we review the evidence supporting a causative link between these two entities as well as the direction of this relationship. We argue that the data favors CMML as the antecedent and causative disease state with a few notable exceptions. Better understanding of this relationship aids clinicians in the education of their patients and in determining the optimal management approach at the bedside. It is important to recognize opportunities to harmonize the treatments of these disease processes, which may enhance the effectiveness of treatment while reducing the burden of adverse effects from redundant therapies.

Effects of Corynebacterium bovis on Engraftment of Patient-derived Chronic-Myelomonocytic Leukemia Cells in NSGS Mice.

Modeling chronic myelomonocytic leukemia (CMML) in immunodeficient NSGS mice relies on unique human CMML specimens and consistent murine engraftment. Only anecdotal comments have thus far supported the notion that research data may be altered by Corynebacterium bovis, an opportunistic cutaneous pathogen of immunodeficient mice. C. bovis disseminated by asymptomatic and clinically affected mice with hyperkeratotic dermatitis, resulting in resilient facility contamination and infectious recurrence. Herein we report that, compared with C. bovis PCR-negative counterparts, C. bovis PCR-positive NSGS mice developed periocular and facial hyperkeratosis and alopecia and had reduced metrics indicative of ineffective human CMML engraftment, including less thrombocytopenia, less splenomegaly, fewer CMML infiltrates in histopathologic sections of murine organs, and fewer human CD45+ cells in samples from murine spleen, bone marrow, and peripheral blood that were analyzed by flow cytometry. All CMML model metrics of engraftment were significantly reduced in the C. bovis PCR-positive cohort compared with the - negative cohort. In addition, a survey of comprehensive cancer center practices revealed that most murine facilities do not routinely test for C. bovis or broadly decontaminate the facility or its equipment after a C. bovis outbreak, thus increasing the likelihood of recurrence of invalidated studies. Our findings document that CMML engraftment of NSGS mice is diminished-and the integrity of murine research data jeopardized-by C. bovis infection of immunodeficient mice. In addition, our results indicate that C. bovis should be excluded from and not tolerated in murine facilities housing immunodeficient strains.

Predictive Model for Infection Risk in Myelodysplastic Syndromes, Acute Myeloid Leukemia, and Chronic Myelomonocytic Leukemia Patients Treated With Azacitidine; Azacitidine Infection Risk Model: The Polish Adult Leukemia Group Study.

BACKGROUND: Myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML) patients, including those treated with azacitidine, are at increased risk for serious infections. The aim of our study was to identify patients with higher infectious risk at the beginning of azacitidine treatment. PATIENTS AND METHODS: We performed a retrospective evaluation of 298 MDS/CMML/AML patients and included in the analysis 232 patients who completed the first 3 cycles of azacitidine therapy or developed Grade III/IV infection before completing the third cycle. RESULTS: Overall, 143 patients (62%) experienced serious infection, and in 94 patients (41%) infection occurred within the first 3 cycles. The following variables were found to have the most significant effect on the infectious risk in multivariate analysis: red blood cell transfusion dependency (odds ratio [OR], 2.38; 97.5% confidence interval [CI], 1.21-4.79), neutropenia <0.8 × 109/L (OR, 3.03; 97.5% CI, 1.66-5.55), platelet count <50 × 109/L (OR, 2.63; 97.5% CI, 1.42-4.76), albumin level <35 g/dL (OR, 2.04; 97.5% CI, 1.01-4.16), and Eastern Cooperative Oncology Group performance status ≥2 (OR, 2.19; 97.5% CI, 1.40-3.54). Each of these variables is assigned 1 point, and the combined score represents the proposed Azacitidine Infection Risk Model. The infection rate in the first 3 cycles of therapy in lower-risk (0-2 score) and higher-risk (3-5 score) patients was 25% and 73%, respectively. The overall survival was significantly reduced in higher-risk patients compared with the lower-risk cohort (8 vs. 29 months). CONCLUSION: We selected a subset with high early risk for serious infection and worse clinical outcome among patients treated with azacitidine.

Targeting cell-bound MUC1 on myelomonocytic, monocytic leukemias and phenotypically defined leukemic stem cells with anti-SEA module antibodies.

Cell surface molecules aberrantly expressed or overexpressed by myeloid leukemic cells represent potential disease-specific therapeutic targets for antibodies. MUC1 is a polymorphic glycoprotein, the cleavage of which yields two unequal chains: a large extracellular α subunit containing a tandem repeat array bound in a strong noncovalent interaction to a smaller ß subunit containing the transmembrane and cytoplasmic domains. Because the α-chain can be released from the cell-bound domains of MUC1, agents directed against the α-chain will not effectively target MUC1+ cells. The MUC1 SEA (a highly conserved protein module so called from its initial identification in a sea urchin sperm protein, in enterokinase, and in agrin) domain formed by the binding of the α and ß chains  represents a stable structure fixed to the cell surface at all times. DMB-5F3, a partially humanized murine anti-MUC1 SEA domain monoclonal antibody, was used to examine MUC1 expression in acute myeloid leukemia (AML) and was found to bind acute myelomonocytic and monocytic leukemia (AML-M4 and AML-M5) cell lines. We also examined monocytic neoplasms freshly obtained from patients including chronic myelomonocytic leukemia and juvenile myelomonocytic leukemia, which were found to uniformly express MUC1. CD34+/lin-/CD38- or CD38+ presumed leukemic stem cell populations from CD34+ AML and CD34-CD38- or CD38+ populations from CD34- AML were also found to express MUC1, although at low percentages. Based on these studies, we generated an anti-MUC1 immunotoxin to directly gauge the cytotoxic efficacy of targeting AML-bound MUC1. Using single-chain DMB-5F3 fused to recombinant gelonin toxin, the degree of AML cytotoxicity was found to correlate with MUC1 expression. Our data support the use of an anti-MUC1 SEA module-drug conjugates to selectively target and inhibit MUC1-expressing myelomonocytic leukemic cells.

A miR-150/TET3 pathway regulates the generation of mouse and human non-classical monocyte subset.

Non-classical monocyte subsets may derive from classical monocyte differentiation and the proportion of each subset is tightly controlled. Deregulation of this repartition is observed in diverse human diseases, including chronic myelomonocytic leukemia (CMML) in which non-classical monocyte numbers are significantly decreased relative to healthy controls. Here, we identify a down-regulation of hsa-miR-150 through methylation of a lineage-specific promoter in CMML monocytes. Mir150 knock-out mice demonstrate a cell-autonomous defect in non-classical monocytes. Our pulldown experiments point to Ten-Eleven-Translocation-3 (TET3) mRNA as a hsa-miR-150 target in classical human monocytes. We show that Tet3 knockout mice generate an increased number of non-classical monocytes. Our results identify the miR-150/TET3 axis as being involved in the generation of non-classical monocytes.

Application of immunophenotypic analysis in distinguishing chronic myelomonocytic leukemia from reactive monocytosis.

OBJECTIVES: The purpose of this study was to determine whether immunophenotypic profiles detected by flow cytometry are useful in differentiating chronic myelomonocytic leukemia (CMML) from reactive monocytosis, and between CMML subtypes. METHODS: Eight-color flow cytometry was used to immunophenotype blasts, monocytes, and granulocytes in the bone marrow of 34 patients with CMML and 12 patients with reactive monocytosis. RESULTS: Bone marrow myeloblast, promonocyte, and monocyte counts by flow cytometry were significantly higher in the CMML group than in the reactive monocytosis group. Myeloblast aberrancies were present in all CMML patients as compared with 2 of 12 (16.7%) reactive monocytosis patients (P < 0.001). The number of blast aberrancies ranged from one to nine (median, four) in CMML patients and 94.1% of CMML cases exhibited ≥ two aberrancies. In contrast, two reactive monocytosis cases showed only one phenotypic abnormality of blasts. Monocyte and granulocyte aberrancies were present in 26 of 34 (76.5%) and in 31 of 34 (91.2%) CMML patients, respectively. Decreased side scatter (SSC) and abnormal CD11b/CD13/CD16 maturation pattern in granulocytes were more frequent in CMML than in reactive monocytosis. No significant differences in antigen expression were detected between the CMML subtypes except that altered CD45/SSC pattern on the blasts was more commonly observed in CMML-0/1 than in CMML-2. CONCLUSIONS: CMML has phenotypic aberrancies in monocytes, granulocytes, and more frequently in myeloblasts. Aberrant expression of two or more antigens in myeloblasts by flow cytometry has a high sensitivity (94.1%) and a high specificity (100%) to differentiate CMML from reactive monocytosis. © 2018 International Clinical Cytometry Society.

Overexpression of Arginase 1 is linked to DNMT3A and TET2 mutations in lower-grade myelodysplastic syndromes and chronic myelomonocytic leukemia.

Immune dysregulation is a common feature of myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML), particularly in early stages. However, the genetic basis remains poorly understood. We recently reported that macrophages from mice deficient in tet methylcytosine dioxygenase 2 (Tet2), a model of MDS/CMML, are hyperinflammatory and have increased expression of arginase 1 (Arg1). In macrophages and myeloid derived suppressor cells (MDSCs) expression of Arg1 contributes to T-cell suppression and immune evasion by L-arginine depletion, in the setting of chronic inflammation and cancer. Since human MDS and CMML are driven by TET2 mutations and associated with chronic inflammation, we hypothesized that arginase enzymatic activity and ARG1 expression would be increased in human MDS/CMML bone marrow. Elevated arginase activity was observed in bone marrow mononuclear cells of MDS and CMML patients with lower-grade features. Immunohistochemical studies confirmed that myelomonocytic cells overexpress ARG1. Additionally, mutations in the epigenetic regulators TET2 and DNMT3A corresponded to high ARG1 expression and activity. These findings suggest ARG1 is a biomarker of immune dysregulation in early MDS and CMML. Recent murine findings have implicated Tet2 and Dnmt3a in regulation of innate immunity. Our study suggests similar changes may be driven by human TET2 and DNMT3A mutations.

Generalized palisaded neutrophilic and granulomatous dermatitis-a cutaneous manifestation of chronic myelomonocytic leukemia? A clinical, histopathological, and molecular study of 3 cases.

Palisaded neutrophilic and granulomatous dermatitis (PNGD) is characterized by erythematous papules or plaques on trunk or limbs and is frequently associated with rheumatologic, autoimmune, or hematologic malignancies. Histopathology shows interstitial granulomas composed of epitheloid histiocytes in the reticular dermis with surrounding foci of collagen degeneration and variable neutrophilic inflammation. We report 3 cases of generalized PNGD associated with chronic myelomonocytic leukemia (CMML), a myelodysplastic/myeloproliferative neoplasm, which may show a variety of cutaneous manifestations. SRSF2 P95 hotspot mutations, found in 40%-50% of CMML cases, were retrospectively detected in skin and bone marrow biopsies of all 3 patients, in 1 of them already 5 years before CMML diagnosis. Generalized PNGD may represent a type of cutaneous manifestation of CMML. Because diagnosis of CMML is frequently difficult in cases with isolated persistent monocytosis and minimal dysplasia in the bone marrow, patients with a generalized PNGD should be evaluated for the presence of hematologic disorders including CMML, ideally supported by mutational analyses.

NOX2-dependent immunosuppression in chronic myelomonocytic leukemia.

Chronic myelomonocytic leukemia (CMML) is a myeloproliferative and myelodysplastic neoplasm with few treatment options and dismal prognosis. The role of natural killer (NK) cells and other antileukemic lymphocytes in CMML is largely unknown. We aimed to provide insight into the mechanisms of immune evasion in CMML with a focus on immunosuppressive reactive oxygen species (ROS) formed by the myeloid cell NADPH oxidase-2 (NOX2). The dominant population of primary human CMML cells was found to express membrane-bound NOX2 and to release ROS, which, in turn, triggered extensive PARP-1-dependent cell death in cocultured NK cells, CD8+ T effector memory cells, and CD8+ T effector cells. Inhibitors of ROS formation and scavengers of extracellular ROS prevented CMML cell-induced lymphocyte death and facilitated NK cell degranulation toward Ab-coated, primary CMML cells. In patients with CMML, elevation of immature cell counts (CD34+) in blood was associated with reduced expression of several NK cell-activating receptors. We propose that CMML cells may use extracellular ROS as a targetable mechanism of immune escape.

Chronic myelomonocytic leukemia mimicking hematologic systemic lupus erythematosus.

The relationship between primary hematologic disease and rheumatologic manifestations is well known, especially acute lymphocytic leukemia, lymphomas, plasma cell dyscrasias and myelodysplastic syndrome (MDS). Currently, more has been described about autoimmune manifestations in chronic myelomonocytic leukemia (CMML). Many different clinical scenarios may lead a patient with MDS/CMML initially to seek a rheumatological unit. Autoimmune features such as polymyalgia rheumatic symptoms, myositis, neutrophilic dermatosis, cutaneous vasculitis and positive antinuclear antibodies (ANA) are some examples of clinical presentation of MDS/CMML. Moreover, peripheral cytopenias are a common initial presentation both for systemic lupus erythematous (SLE) and MDS/CMML. The aim of this study was to describe a case of an elderly woman with thrombocytopenia and positivity of antibodies to anti-extractable nuclear antigens (anti-ENA) as initial manifestation of CMML mimicking SLE, and to present some clues that encourage the clinician to perform a bone marrow study in such a clinical scenario.

Chronic inflammation and autoimmunity as risk factors for the development of chronic myelomonocytic leukemia?

In this study, we investigate if chronic inflammation and autoimmunity might be related to the development of chronic myelomonocytic leukemia (CMML). Conducting a case-control study, we included 112 CMML subjects diagnosed at three hematological departments in Denmark between 2003 and 2013. Controls were 231 unmatched chronic lymphatic leukemia (CLL) subjects diagnosed at one of the departments between 2003 and 2012. Subjects with a history of chronic inflammation or autoimmune disorders were retrieved and odds ratios (ORs) calculated. 16.1% of CMML subjects and 6.5% of CLL subjects presented with a history of chronic inflammatory or autoimmune conditions. This was significantly associated with an increased risk of CMML (adjusted OR 3.24, 95% CI: 1.5-7.0). At individual levels, this association was statistically significant for polymyalgia rheumatica and ITP (p values < 0.01 and 0.03, respectively). We found an association of CMML and smoking status (OR 1.42, 95% CI: 1.06-1.90) with more "former smokers" in the CMML group.

Systemic inflammatory and autoimmune manifestations associated with myelodysplastic syndromes and chronic myelomonocytic leukaemia: a French multicentre retrospective study.

OBJECTIVE: We describe myelodysplastic syndrome (MDS)-associated systemic inflammatory and autoimmune diseases (SIADs), their treatments and outcomes and the impact of SIADs on overall survival in a French multicentre retrospective study. METHODS: In this study, 123 patients with MDS and SIADs were analysed. RESULTS: Mean age was 70 years (s.d. 13) and the male:female ratio was 2. The SIADs were systemic vasculitis in 39 (32%) cases, CTD in 31 (25%) cases, inflammatory arthritis in 28 (23%) cases, a neutrophilic disorder in 12 (10%) cases and unclassified in 13 cases (11%). The SIADs fulfilled the usual classification criteria in 75 (66%) cases, while complete criteria were not reached in 21 (19%) cases. A significant association was shown between chronic myelomonocytic leukaemia (CMML) and systemic vasculitis (P = 0.0024). One hundred and eighteen (96%) SIAD patients were treated (91% with steroids), with an 83% response to first-line treatment, including 80% for steroids alone. A second-line treatment for SIADs was required for steroid dependence or relapse in 48% of cases. The effect of MDS treatment on SIADs could be assessed in 11 patients treated with azacytidine and SIAD response was achieved in 9/11 (80%) and 6/11 (55%) patients at 3 and 6 months, respectively. Compared with 665 MDS/CMML patients without SIADs, MDS/CMML patients with SIADs were younger (P < 0.01), male (P = 0.03), less often had refractory anaemia with ring sideroblasts (P < 0.01), more often had a poor karyotype (16% vs 11%, P = 0.04) and less frequently belonged to low and intermediate-1 International Prognostic Scoring System categories, but no survival difference was seen between patients with MDS-associated SIADs and without SIADs (P = 0.5). CONCLUSION: The spectrum of SIADs associated to MDS is heterogeneous, steroid sensitive, but often steroid dependent.

Chronic myelomonocytic leukemia as a cause of fatal uncontrolled inflammation in familial Mediterranean fever.

We report on a familial Mediterranean fever (FMF) patient homozygous for p.M694V in the MEFV gene who developed chronic myelomonocytic leukemia (CMML) leading to an uncontrolled and fatal inflammatory syndrome. Plasma levels of IL-6 and IL-18 were found to be very high, as compared to healthy controls and CMML-free FMF patients.Our study unveils the interplay between two different disorders involving the same target cells, suggesting that in myelodysplasia with inflammatory manifestations, mutations in genes causing autoinflammatory syndromes, like MEFV, can be present and thus could be sought. Early chemotherapy with interleukin inhibitors could be proposed in such unusual situations.

Flow cytometry immunophenotypic findings in chronic myelomonocytic leukemia and its utility in monitoring treatment response.

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic/myeloproliferative neoplasm, characterized by persistent monocytosis. Due to the lack of unique surface markers expressed by neoplastic monocytes and the frequent CD34-negative blast immunophenotype, the diagnostic value of flow cytometric immunophenotyping (FCI) in CMML is rarely studied. In this study, by using a multicolor FCI assay, we assessed bone marrow (BM) immunophenotypical alterations in 118 CMML patients and follow-up BM samples in 35 of these patients. The median BM monocytes as determined by FCI were 14% (1-63%), correlated with morphologic count (P = 0.0004). FCI alterations in monocytes were observed in 96% and granulocytes in 83% of cases. The percentage of CD34(+) myeloblasts by FCI was low [median 0.6% (0.02-12.6%)], but exhibiting frequent aberrancies [median 6 (2-12)]. CD34(+) B-cell precursors were absent in 93% of cases. In 35 patients with follow-up BM samples assessed, the CD34(+) myeloblasts showed persistent FCI aberrancies in all 29 patients treated with hypomethylating agents and 3 patients on observation, but became normal in 3 patients following stem cell transplant. In conclusion, CMML exhibit numerous FCI alterations in monocytes, granulocytes, and more profound/frequent in CD34(+) myeloblasts. These findings provide solid evidence for using FCI as an ancillary test in CMML diagnosis and also, in assessment of treatment responses.