Cytokine-like protein 1-induced survival of monocytes suggests a combined strategy targeting MCL1 and MAPK in CMML.

Mouse models of chronic myeloid malignancies suggest that targeting mature cells of the malignant clone disrupts feedback loops that promote disease expansion. Here, we show that in chronic myelomonocytic leukemia (CMML), monocytes that accumulate in the peripheral blood show a decreased propensity to die by apoptosis. BH3 profiling demonstrates their addiction to myeloid cell leukemia-1 (MCL1), which can be targeted with the small molecule inhibitor S63845. RNA sequencing and DNA methylation pattern analysis both point to the implication of the mitogen-activated protein kinase (MAPK) pathway in the resistance of CMML monocytes to death and reveal an autocrine pathway in which the secreted cytokine-like protein 1 (CYTL1) promotes extracellular signal-regulated kinase (ERK) activation through C-C chemokine receptor type 2 (CCR2). Combined MAPK and MCL1 inhibition restores apoptosis of monocytes from patients with CMML and reduces the expansion of patient-derived xenografts in mice. These results show that the combined inhibition of MCL1 and MAPK is a promising approach to slow down CMML progression by inducing leukemic monocyte apoptosis.

Characteristic repartition of monocyte subsets as a diagnostic signature of chronic myelomonocytic leukemia.

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic syndrome/ myeloproliferative neoplasm whose diagnosis is currently based on the elevation of peripheral blood monocytes to >1 × 10(9)/L, measured for ≥3 months. Diagnosis can be ambiguous; for example, with prefibrotic myelofibrosis or reactive monocytosis. We set up a multiparameter flow cytometry assay to distinguish CD14(+)/CD16(-) classical from CD14(+)/CD16(+) intermediate and CD14(low)/CD16(+) nonclassical monocyte subsets in peripheral blood mononucleated cells and in total blood samples. Compared with healthy donors and patients with reactive monocytosis or another hematologic malignancy, CMML patients demonstrate a characteristic increase in the fraction of CD14(+)/CD16(-) cells (cutoff value, 94.0%). The associated specificity and sensitivity values were 95.1% and 90.6% in the learning cohort (175 samples) and 94.1% and 91.9% in the validation cohort (307 samples), respectively. The accumulation of classical monocytes, which demonstrate a distinct gene expression pattern, is independent of the mutational background. Importantly, this increase disappears in patients who respond to hypomethylating agents. We conclude that an increase in the fraction of classical monocytes to >94.0% of total monocytes is a highly sensitive and specific diagnostic marker that rapidly and accurately distinguishes CMML from confounding diagnoses.

Clonal architecture of chronic myelomonocytic leukemias.

Genomic studies in chronic myeloid malignancies, including myeloproliferative neoplasms (MPN), myelodysplastic syndromes (MDS), and MPN/MDS, have identified common mutations in genes encoding signaling, epigenetic, transcription, and splicing factors. In the present study, we interrogated the clonal architecture by mutation-specific discrimination analysis of single-cell-derived colonies in 28 patients with chronic myelomonocytic leukemias (CMML), the most frequent MPN/MDS. This analysis reveals a linear acquisition of the studied mutations with limited branching through loss of heterozygosity. Serial analysis of untreated and treated samples demonstrates a dynamic architecture on which most current therapeutic approaches have limited effects. The main disease characteristics are early clonal dominance, arising at the CD34(+)/CD38(-) stage of hematopoiesis, and granulomonocytic differentiation skewing of multipotent and common myeloid progenitors. Comparison of clonal expansions of TET2 mutations in MDS, MPN, and CMML, together with functional invalidation of TET2 in sorted progenitors, suggests a causative link between early clonal dominance and skewed granulomonocytic differentiation. Altogether, early clonal dominance may distinguish CMML from other chronic myeloid neoplasms with similar gene mutations.

MYH10 protein expression in platelets as a biomarker of RUNX1 and FLI1 alterations.

RUNX1 gene alterations are associated with acquired and inherited hematologic malignancies that include familial platelet disorder/acute myeloid leukemia, primary or secondary acute myeloid leukemia, and chronic myelomonocytic leukemia. Recently, we reported that RUNX1-mediated silencing of nonmuscle myosin heavy chain IIB (MYH10) was required for megakaryocyte ploidization and maturation. Here we demonstrate that runx1 deletion in mice induces the persistence of MYH10 in platelets, and a similar persistence was observed in platelets of patients with constitutional (familial platelet disorder/acute myeloid leukemia) or acquired (chronic myelomonocytic leukemia) RUNX1 mutations. MYH10 was also detected in platelets of patients with the Paris-Trousseau syndrome, a thrombocytopenia related to the deletion of the transcription factor FLI1 that forms a complex with RUNX1 to regulate megakaryopoiesis, whereas MYH10 persistence was not observed in other inherited forms of thrombocytopenia. We propose MYH10 detection as a new and simple tool to identify inherited platelet disorders and myeloid neoplasms with abnormalities in RUNX1 and its associated proteins.

Decitabine Versus Hydroxyurea for Advanced Proliferative Chronic Myelomonocytic Leukemia: Results of a Randomized Phase III Trial Within the EMSCO Network.

PURPOSE: Hydroxyurea (HY) is a reference treatment of advanced myeloproliferative neoplasms. We conducted a randomized phase III trial comparing decitabine (DAC) and HY in advanced myeloproliferative chronic myelomonocytic leukemias (CMML). PATIENTS AND METHODS: Newly diagnosed myeloproliferative CMML patients with advanced disease were randomly assigned 1:1 to intravenous DAC (20 mg/m2/d days 1-5) or HY (1-4 g/d) in 28-day cycles. The primary end point was event-free survival (EFS), events being death and acute myelomonocytic leukemia (AML) transformation or progression. RESULTS: One-hundred seventy patients received DAC (n = 84) or HY (n = 86). Median age was 72 and 74 years, and median WBC count 32.5 × 109/L and 31.2 × 109/L in the DAC and HY arms, respectively. Thirty-three percent of DAC and 31% of HY patients had CMML-2. Patients received a median of five DAC and six HY cycles. With a median follow-up of 17.5 months, median EFS was 12.1 months in the DAC arm and 10.3 months in the HY arm (hazard ratio [HR], 0.83; 95% CI, 0.59 to 1.16; P = .27). There was no significant interaction between treatment effect and blast or platelet count, anemia, CMML Prognostic Scoring System, Groupe Francophone des Myelodysplasies, or CMML Prognostic Scoring System-mol risk. Fifty-three (63%) DAC patients achieved a response compared with 30 (35%) HY patients (P = .0004). Median duration of response was similar in both arms (DAC, 16.3 months; HY, 17.4 months; P = .90). Median overall survival was 18.4 months in the DAC arm and 21.9 months in the HY arm (P = .67). Compared with HY, DAC significantly reduced the risk of CMML progression or transformation to acute myelomonocytic leukemia (cause-specific HR, 0.62; 95% CI, 0.41 to 0.94; P = .005) at the expense of death without progression or transformation (cause-specific HR, 1.55; 95% CI, 0.82 to 2.9; P = .04). CONCLUSION: Compared with HY, frontline treatment with DAC did not improve EFS in patients with advanced myeloproliferative CMML (ClinicalTrials.gov identifier: NCT02214407).

Dynamic gene regulation by nuclear colony-stimulating factor 1 receptor in human monocytes and macrophages.

Despite their location at the cell surface, several receptor tyrosine kinases (RTK) are also found in the nucleus, as either intracellular domains or full length proteins. However, their potential nuclear functions remain poorly understood. Here we find that a fraction of full length Colony Stimulating Factor-1 Receptor (CSF-1R), an RTK involved in monocyte/macrophage generation, migrates to the nucleus upon CSF-1 stimulation in human primary monocytes. Chromatin-immunoprecipitation identifies the preferential recruitment of CSF-1R to intergenic regions, where it co-localizes with H3K4me1 and interacts with the transcription factor EGR1. When monocytes are differentiated into macrophages with CSF-1, CSF-1R is redirected to transcription starting sites, colocalizes with H3K4me3, and interacts with ELK and YY1 transcription factors. CSF-1R expression and chromatin recruitment is modulated by small molecule CSF-1R inhibitors and altered in monocytes from chronic myelomonocytic leukemia patients. Unraveling this dynamic non-canonical CSF-1R function suggests new avenues to explore the poorly understood functions of this receptor and its ligands.

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.

Engraftment of chronic myelomonocytic leukemia cells in immunocompromised mice supports disease dependency on cytokines.

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder that typically associates with mutations in epigenetic, splicing, and signaling genes. Genetically modified mouse models only partially recapitulate the disease phenotype, whereas xenotransplantation of CMML cells in immunocompromised mice has been rarely successful so far. Here, CMML CD34+ cells sorted from patient bone marrow (BM) or peripheral blood (PB) were injected intravenously into NSG (NOD/LtSz-scid IL2rγnull) mice and NSG mice engineered to express human granulo-monocyte colony-stimulating factor, stem cell factor, and interleukin-3 (NSGS mice). Fifteen out of 16 patient samples (94%) successfully engrafted into NSG or NSGS or both mouse strains. The expansion of human cells, predominant in the BM, was also observed in the spleen and the PB and was greatly enhanced in mice producing the 3 human cytokines. Gene mutations identified in engrafted cells were mostly similar to those identified in patient cells before injection. Successful secondary engraftment was obtained in NSGS mice in 3 out of 10 attempts. Thus, primary CMML leukemic cells expand much better in NSGS compared with NSG mice with limited efficacy of secondary transplant.

Mutation allele burden remains unchanged in chronic myelomonocytic leukaemia responding to hypomethylating agents.

The cytidine analogues azacytidine and 5-aza-2'-deoxycytidine (decitabine) are commonly used to treat myelodysplastic syndromes, with or without a myeloproliferative component. It remains unclear whether the response to these hypomethylating agents results from a cytotoxic or an epigenetic effect. In this study, we address this question in chronic myelomonocytic leukaemia. We describe a comprehensive analysis of the mutational landscape of these tumours, combining whole-exome and whole-genome sequencing. We identify an average of 14±5 somatic mutations in coding sequences of sorted monocyte DNA and the signatures of three mutational processes. Serial sequencing demonstrates that the response to hypomethylating agents is associated with changes in DNA methylation and gene expression, without any decrease in the mutation allele burden, nor prevention of new genetic alteration occurence. Our findings indicate that cytosine analogues restore a balanced haematopoiesis without decreasing the size of the mutated clone, arguing for a predominantly epigenetic effect.

Prognostic score including gene mutations in chronic myelomonocytic leukemia.

PURPOSE: Several prognostic scoring systems have been proposed for chronic myelomonocytic leukemia (CMML), a disease in which some gene mutations-including ASXL1-have been associated with poor prognosis in univariable analyses. We developed and validated a prognostic score for overall survival (OS) based on mutational status and standard clinical variables. PATIENTS AND METHODS: We genotyped ASXL1 and up to 18 other genes including epigenetic (TET2, EZH2, IDH1, IDH2, DNMT3A), splicing (SF3B1, SRSF2, ZRSF2, U2AF1), transcription (RUNX1, NPM1, TP53), and signaling (NRAS, KRAS, CBL, JAK2, FLT3) regulators in 312 patients with CMML. Genotypes and clinical variables were included in a multivariable Cox model of OS validated by bootstrapping. A scoring system was developed using regression coefficients from this model. RESULTS: ASXL1 mutations (P < .0001) and, to a lesser extent, SRSF2 (P = .03), CBL (P = .003), and IDH2 (P = .03) mutations predicted inferior OS in univariable analysis. The retained independent prognostic factors included ASXL1 mutations, age older than 65 years, WBC count greater than 15 ×10(9)/L, platelet count less than 100 ×10(9)/L, and anemia (hemoglobin < 10 g/dL in female patients, < 11g/dL in male patients). The resulting five-parameter prognostic score delineated three groups of patients with median OS not reached, 38.5 months, and 14.4 months, respectively (P < .0001), and was validated in an independent cohort of 165 patients (P < .0001). CONCLUSION: A new prognostic score including ASXL1 status, age, hemoglobin, WBC, and platelet counts defines three groups of CMML patients with distinct outcomes. Based on concordance analysis, this score appears more discriminative than those based solely on clinical parameters.