Chronic Myelomonocytic Leukemia Patients Research Articles

Diphtheria Toxin Fused to Granulocyte-Macrophage Colony-Stimulating Factor Is Toxic to Blasts From Patients With Juvenile Myelomonocytic Leukemia and Chronic Myelomonocytic Leukemia

AbstractWe have previously demonstrated that human granulocyte-macrophage colony-stimulating factor fused to a truncated diphtheria toxin (DT388-GM-CSF) is toxic to patient acute myeloid leukemia progenitors bearing the GM-CSF receptor, but not normal marrow progenitors. We now report that exposure of mononuclear cells from five of seven (71%) juvenile myelomonocytic leukemia (JMML) patients and from 12 of 20 (60%) adult chronic myelomonocytic leukemia (CMML) patients to 10-9 mol/L DT388-GM-CSF for 48 hours in culture reduces the number of cells capable of forming colonies in semisolid medium (colony-forming units–leukemia) 10-fold to 300-fold (1 to 2.5 log decrease). In contrast, normal myeloid progenitors (colony-forming unit–granulocyte-macrophage) from six different donors treated and assayed under identical conditions were consistently insensitive to the same fusion toxin even when treated as highly purified CD34+ cells. The leukemic progenitors from the two other JMML patients showed intermediate sensitivity to DT388-GM-CSF and the leukemic progenitors from eight of the 20 (40%) CMML patients were not different from normal progenitors. Parallel measurements of the number and affinity of GM-CSF receptors on cells from the same samples showed no consistent differences between JMML, CMML, and normal light density or CD34+ bone marrow cells. The increased sensitivity of leukemic progenitors from all JMML progenitors and some CMML patients to the fusion toxin is therefore not likely to be explained by an increased density of GM-CSF receptors on these cells. We also examined the DT388-GM-CSF sensitivity of two murine cell lines transfected with cDNAs encoding varying portions of the human GM-CSF receptor α and/or β chains. These studies showed that high-affinity ligand binding was sufficient for DT388-GM-CSF–induced toxicity, as this could occur even in the absence of functional signal transduction and that the background of the host cell had a major influence on the degree to which this decreased the toxicity of DT388-GM-CSF. The selective sensitivity to DT388-GM-CSF of leukemic progenitors from a majority of JMML and CMML patients suggests that this agent could have therapeutic potential for some patients with these diseases.

Curcumol and FTY720 synergistically induce apoptosis and differentiation in chronic myelomonocytic leukemia via multiple signaling pathways.

Chronic myelomonocytic leukemia (CML) is a myeloid tumor characterized by MDS (myelodysplastic syndrome) and MPN (myeloproliferative neoplasms). Allogeneic hematopoietic stem cell transplantation, chemotherapy, interferon, and targeted therapy are the main treatment methods for CML. Tyrosine kinase inhibitors (TKIs) are also a treatment option, and patients are currently recommended to take these drugs throughout their lives to prevent CML recurrence. Therefore, there is a need to investigate and identify other potential chemotherapy drugs. Currently, research on CML treatment with a single drug has shown little progress. Fingolimod (FTY720), an FDA-approved drug used to treat relapsing multiple sclerosis, has also shown great potential in the treatment of lymphocytic leukemia. In our study, we find that FTY720 and curcumol have a significant inhibitory effect on K562 cells, K562/ADR cells, and CD34+ cells from CML patients. RNAseq data analysis shows that regulation of apoptosis and differentiation pathways are key pathways in this process. Besides, BCR/ABL-Jak2/STAT3 signaling, PI3K/Akt-Jnk signaling, and activation of BH3-only genes are involved in CML inhibition. In a K562 xenograft mouse model, therapy with curcumol and FTY720 led to significant inhibition of tumor growth and induction of apoptosis. To summarize, curcumol and FTY720 synergistically inhibit proliferation involved in differentiation and induce apoptosis in CML cells. Therefore, synergistic treatment with two drugs could be the next choice of treatment for CML.

Cytogenetic and molecular landscape and its potential clinical significance in Hispanic CMML patients from Puerto Rico.

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic neoplasm that exhibits myelodysplastic and myeloproliferative characteristics with heterogeneous clinical and pathological features. There are limited publications on the ethnic and racial disparity of cytogenetics and genomics in CMML patients. This study aims to define the cytogenetic and molecular landscape in Hispanic CMML patients from Puerto Rico and explore its possible clinical significance. One hundred and eleven (111) Hispanic CMML patients from Puerto Rico were diagnosed in our institute from 2009 to 2018. Karyotypes were available in one hundred and seven (107) patients. Seventeen (17) patients had abnormal karyotypes (17/107, 16%). Compared to previously published data, Hispanic CMML patients in this study had significantly lower rates of overall cytogenetic abnormalities (16% vs 27–28%, p < 0.05) and trisomy 8 (2% vs 7%, p < 0.05). Among one hundred and eleven (111) Hispanic CMML patients, 40-gene myeloid molecular profile tests were performed in fifty-six (56) CMML patients. Gene mutations were identified in fifty-four (54) patients (96%). The most frequent mutated genes were: TET2, SRSF2, ASXL1, ZRSR2, DNMT3A, NRAS, CBL, and RUNX1. Twenty-nine (29) out of fifty-six (56) patients (29/56, 52%) had mutated TET2/wild type ASXL1 (muTET2/wtASXL1). Previous studies indicated that mutated ASXL1, DNMT3A, NRAS, RUNX1, and SETBP1 may associate with an unfavorable prognosis and muTET2/wtASXL1 may associate with a favorable prognosis in CMML patients. Compared to previously published data, Hispanic CMML patients from Puerto Rico in this study had significantly lower mutation rates in ASXL1 and SETBP1, and a higher rate of muTET2/wtASXL1. The findings raise the possibility of a favorable prognosis in Hispanic CMML patients.

Eltrombopag in Chronic Myelomonocytic Leukemia (CMML) with Severe Thrombocytopenia: Final Results of a Multicenter Phase II Study

Eltrombopag in Chronic Myelomonocytic Leukemia (CMML) with Severe Thrombocytopenia: Final Results of a Multicenter Phase II Study

Gene Body Methylation and Transcriptional Activity in ASXL1-Mutant Chronic Myelomonocytic Leukemia

Introduction: Truncating mutations in Additional Sex Combs-Like 1 (ASXL1) are associated with a high-risk disease phenotype in myeloid malignancies. In chronic myelomonocytic leukemia (CMML), truncating ASXL1 mutations are known to increase transcriptional activity of leukemic driver genes and have been associated with gene body hypermethylation. We interrogated the transcriptome and methylome of patients with ASXL1-mutant (MT) and -wildtype (WT) CMML using a multi-omics approach to test the hypothesis that gene expression is mediated through gene body methylation. Methods: Bone marrow mononuclear cells from patients with ASXL1 WT (n=8) and MT (n=8) CMML were subjected to targeted NGS of DNA, whole transcriptome shotgun sequencing (RNA-seq), and immunoprecipitation of DNA methyl residues (DIP-seq). After quality control all samples were sequenced on an Illumina HiSeq 4000 before further processing and data analysis. Differential gene expression analysis was performed to identify genes up-regulated in MT CMML. The samples in the two groups were treated as biological replicates and subjected to a consensus peak calling strategy requiring an overlap of at least 30% between samples and an adjusted p-value &amp;lt; 5x10-5 for a methylation peak to be considered statistically significant. For validation purposes methylation analysis was performed on 3 ASXL1 MT and 3 WT CMML patients using Illumina Infinium MethylationEPIC microarrays and differentially methylated regions were identified using a bump hunting strategy. Gene body methylation was defined as methylation in gene bodies (outside the promoter region, i.e. transcription start site ±2kb). Gene body methylation was compared between WT and MT CMML for the up-regulated genes and correlated with expression of all genes in MT CMML. Results: Sixteen WHO-defined CMML patients were included, median age 69 years (48-77), 63% male, 50% had truncating ASXL1 frame shift mutations. Abnormal karyotypes were observed in the same number of patients and the burden of co-mutations was similar between the two groups (median number per group 3 vs. 3, p=0.508). This included several modulators of DNA methylation including TET2, DNMT3A, and IDH2 (median number per group 1 vs. 1, p=0.699). There was a predominant up-regulation of gene expression in MT CMML: 707 genes up- and 124 down-regulated (FDR&amp;lt;0.050) without evidence of differential methylation in promoter regions of the differentially expressed genes. There was no difference in the number of genes with consensus methylation peaks in the gene body or the extent of gene body methylation (area under the consensus peaks) between MT and WT CMML for the differentially expressed genes (Figure 1a). We further validated these results using methylation microarrays (Figure 1b). Among the MT CMML patients, there was a curvilinear relationship between gene body methylation and gene expression across all genes with intermediate gene body methylation being associated with the highest gene expression (Figure 1c). As an alternative unbiased approach, we identified 1595 differentially methylated regions (DMR, regions with FDR&amp;lt;0.05) in the validation data set. We mapped all hypermethylated regions to gene bodies requiring that there was no concurrent hypermethylation of the promoter region of the same gene. With this approach we identified one of the 707 up-regulated genes (0.14%) with evidence of isolated gene body hypermethylation (HBZ, log2-fold change in gene expression 4.25, FDR=0.0008, DMR area=1.61, DMR FDR=0.018). Representative examples of up-regulated mitotic kinases without evidence of differential gene body methylation are shown in Figure 1d (pie charts represent the mean β-values of microarray probes, p-values represent the comparisons of mean β-values between MT and WT CMML per gene). Conclusions: Gene body methylation was positively associated with gene expression in MT CMML. However, the lack of differential gene body methylation between WT and MT CMML for the up-regulated genes make it an unlikely explanation for the observed increase in transcriptional activity among patients with MT CMML. Figure 1 Disclosures Ordog: Millipore Sigma: Patents &amp; Royalties.

Hypomethylating Agent Therapy for Chronic Myelomonocytic Leukemia Does Not Impact Acute Myeloid Leukemia Transformation or Survival

Background: Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder with features of both myeloproliferative neoplasm and myelodysplastic syndrome (MDS). CMML is characterized by persistent blood monocytosis &amp;gt;1 x 109/L, bone marrow dysplasia in one or more hematopoietic cell lines, and increased risk of transformation to acute myeloid leukemia (AML). Our review of SEER Medicare data (Haematologica 2013;98:584) demonstrated that, compared to MDS, CMML has shorter overall survival (OS) and more frequent progression to AML. Hypomethylating agents (HMAs) have become standard therapy for CMML, with reported response rates of 37-69%, but their impact on AML transformation and OS is unclear. Methods: We retrospectively reviewed CMML patients treated at the University of Maryland Greenebaum Comprehensive Cancer Center between January 2000 and December 2019. Clinical characteristics, treatments, AML progression, time to AML progression (TTP), and OS were recorded and analyzed. Descriptive statistics were used for baseline characteristics and Kaplan-Meier analysis was performed for time-to-event data. Statistical analyses were performed using GraphPad Prism 8®. Results: We identified 71 patients with CMML, 82% male and 73% white, with a median age of 69 (range 25 - 96) years; 51% had &amp;lt;10% bone marrow (BM) blasts and 45% had low-risk cytogenetic findings (normal karyotype or -Y). Most patients treated prior to 2005 received hydroxyurea and/or erythropoiesis-stimulating agents or were enrolled on clinical trials, while patients treated since 2005 received HMAs as primary therapy. Median follow-up was 41.1 months. The median OS of the entire cohort was 20 months, with 46% of patients progressing to AML with a median TTP of 11.5 months. By the MD Anderson Prognostic Scoring System at time of diagnosis, CMML was low-risk in 24 patients, intermediate-1 in 16, intermediate-2 in 14, and high-risk in 17. Forty-six patients received HMAs, with an overall response rate (ORR) of 54% (complete response or partial response), while 25 patients did not receive HMAs. Patient and disease characteristics were similar in HMA- and non-HMA-treated patients (Table 1). The estimated OS of HMA-treated patients was 20 months, compared to 14 months for non-HMA-treated patients (p =0.43) (Figure 1). AML transformation occurred in 52% of patients treated with HMAs, with TTP ranging from 3 to 65 months, and in 33% patients not treated with HMAs, with TTP ranging from 5 to 47 months. Most patients receiving HMAs (63%) received ≥ 6 cycles; 46% transformed to AML despite initial response, often in a sudden and unpredictable manner. HMAs were azacitidine in 13 patients, decitabine in 24, azacitidine followed by decitabine in 4, and decitabine followed by azacitidine in 5. Five CMML patients in our cohort underwent allogenic stem cell transplantation. Four of the five relapsed with transformation to AML post transplant, and only one patient remains in remission, 9 months post transplant. Conclusions: Despite a 54% ORR, HMA treatment did not have a significant impact on frequency of AML transformation, or OS in our cohort. Based on our data, favorable response rates previously reported with HMAs and also seen in our patients do not appear to translate into decreased frequency of AML transformation or prolonged OS. Though our study is a retrospective study with inherent selection bias, our results underscore the ongoing need for novel therapies and for clinical trials for CMML patients. Disclosures Niyongere: Kartos Therapeutics: Other: Received clinical trial research support with Kartos Therapeutics ; Forty Seven: Other: Received clinical trial research support with Forty Seven. Emadi:Amgen: Membership on an entity's Board of Directors or advisory committees; KinaRx: Other: co-founder and scientific advisor; NewLink Genetics: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Research Funding. Doung:Pfizer: Membership on an entity's Board of Directors or advisory committees, Other: clinical trial research support; Incyte: Other: clinical trial research support; Astex: Other: clinical trial research support; MedPacto: Other: clinical trial research support. Baer:Takeda: Other: Institutional research funding; Oscotec: Other: Institutional research funding; Kite: Other: Institutional research funding; Incyte: Other: Institutional research funding; Forma: Other: Institutional research funding; Astellas: Other: Institutional research funding; AbbVie: Other: Institutional research funding.

Implementation of Flow Cytometric Monocyte Repartition Assay for Assessment of Chronic Myelomonocytic Leukaemia (CMML) in Bone Marrow

Background: CMML is a myelodysplastic/myeloproliferative overlap syndrome associated with persistent monocytosis. Previous studies have shown a characteristic phenotype of peripheral blood (PB) monocytes in CMML that may have diagnostic utility. There is expansion of the classical monocyte (Mo1) population (CD14+CD16-) with concomitant reduction in the intermediate (Mo2; CD14+16+) and non-classical (Mo3; CD14-16+) populations. It is unclear whether an increased Mo1 population or a reduced Mo2/Mo3 population is a better discriminator in detecting CMML by flow cytometry. Diagnostic thresholds for these populations have most often been established by comparison with normal donors using PB samples. The objective of this study was to determine the optimal cut-off limits for flow cytometric monocyte repartition (FMR) in bone marrow (BM) samples and to assess the diagnostic accuracy of this method in patients undergoing BM evaluation for other causes of monocytosis using a novel gating strategy. Patients/Methods: 71 BM aspirates were analysed comprising 35 confirmed CMML (21 proliferative CMML , 14 dysplastic CMML), 13 other myeloid neoplasm (MN) disease controls and 23 normal bone marrow aspirates. The MN cohort was identified through local samples with a known peripheral blood monocytosis of ≥1.0x109 and peripheral blast count of &amp;lt;20% not fulfilling criteria for CMML. The MN cohort comprised of 4 cases of chronic myeloid leukaemia (CML), 2 cases of myelodysplasia/myeloproliferative neoplasm unspecified (MDS/MPN-U), two cases of atypical CML (aCML), 2 cases of primary myelofibrosis, 1 case of juvenile myelomonocytic leukaemia (JMML), 1 case of chronic neutrophilic leukaemia (CNL) and 1 case of therapy-related acute myeloid leukaemia (T-AML). The median age of CMML patients within our cohort was 74 years (range 44- 89 years) and 77% were male. Stored flow cytometric data were reanalysed to assess monocyte subsets. After initial removal of doublets and non-cellular events, sequential gating selected a CD45+CD33bright population with low side scatter to select monocytes and exclude granulocytes. The lymphocyte gate as determined on the CD45 vs CD33 plot was used to establish a threshold for CD16 positivity. Immature double negative monocytes (CD14-CD16-) were excluded as in published gating strategies. Results: Linear regression analysis of the percentage of both the Mo1 and Mo2 populations demonstrated a significant difference between the CMML, MN, and normal cohorts (global P&amp;lt;0.0001). Post hoc analysis demonstrated a significant increase in the Mo1% fraction (mean 92.5%; 95% Confidence Interval [CI]: 88.1%, 96.9%) in CMML cases when compared to the normal BM cohort (mean 63.5%; 95% CI: 58.1%, 69.0%; comparison P &amp;lt;0.0001) and the MN cohort (mean 79.9%; 95% CI: 72.7%,87.2%; comparison P = 0.004). Conversely, the Mo2% was significantly decreased (mean 6.8% 95% CI: 2.7%, 10.9%) in CMML cases when compared to the normal cohort (mean 33.0%; 95% CI: 27.9%; 38.1%; comparison P value &amp;lt;0.0001) and the MN cohort (mean 17.6%; 95% CI 10.8%; 24.3%; comparison P value 0.008). Receiver Operator Curve (ROC) curve analysis of the Mo1 population demonstrated an area under the curve (AUC) of 0.8738 (95% CI: 0.7897, 0.9579; P&amp;lt;0.0001) with a marginally lower AUC for Mo2% (Figure 1A). Priority was given to selecting a cut-off value with higher specificity, considering that the BM examination is not a screening test. A cut-off value for Mo1% of &amp;gt;88.5% (Figure 1B) gave a sensitivity of 77.1% (95% CI: 60.98%, 87.93%) and specificity of 88.9% (95% CI: 74.69%, 95.59%) (Figure 1A). A Mo2% cut-off value of &amp;lt;12.25% (Figure 1C) gave a sensitivity of 78.8% (95% CI: 62.25%, 89.32%) with a specificity of 80.6% (95% CI: 64.97%, 90.25%) (Figure 1A). Eight patients with CMML were misclassified by the Mo1/Mo2 criteria. Conclusion: Our study confirms that analysis of monocyte subsets on BM samples provides good discrimination of CMML cases when compared to normal controls. There was significant overlap with other MN samples. FMR may be a useful adjunct to BM morphology in cases with subtle dysplasia. Further study is required to understand the overlap in monocyte phenotype between CMML and other myeloid neoplasms. Disclosures Allen: Amgen: Other: Travel Support; Roche: Other: Travel Support; Novartis: Other: Travel Support. Hahn:Roche: Honoraria; Astra Zeneca: Honoraria.

A Population-Based Study of Chronic Myelomonocytic Leukemia in the United States from 2004-2015

Background: Chronic myelomonocytic leukemia (CMML) is a rare chronic myeloid malignancy with a poor prognosis. There are few epidemiologic studies on CMML. We studied population-based outcomes in CMML using the Surveillance, Epidemiology, and End Results (SEER) and the National Cancer Database (NCDB). Methods: The SEER 18 registries and NCDB Participant User File were used to identify patients with ICD-O-3 diagnosis code 9945/3 from 2004-2015. Incidence was identified using SEER and age-adjusted to the U.S. 2000 standard population. Causes of death were obtained and CMML-related death was defined as death from any myeloid disorder (CMML, acute monocytic leukemia, acute myeloid leukemia [AML], chronic myeloid leukemia, other myeloid/monocytic leukemia, and aleukemic, subleukemic, and NOS) to avoid misattribution. Relative survival (RS) was defined as the ratio of the proportion of observed survivors in a cohort of CMML patients to the proportion of expected survivors in a comparable set of individuals that did not have CMML, adjusting for the general survival of the US population for race, sex, age, and time when the diagnosis was established. Time to AML was calculated using the left-truncated life tables session and a 3 month latency period was used to prevent misattribution. Per the NCDB's system on classifying treatment, hydroxyurea, decitabine, and azacitidine are considered chemotherapy. The Kaplan-Meier method was used to calculate overall survival (OS), and Cox regression model was used to identify predictors of survival. Variables significant in univariate analysis (age, Charlson Deyo score [CDS], insurance type, and treatment facility type) were included in a multivariate analysis. Statistical analyses were performed using SAS version 9.0. Results: In the SEER database (n=4437), the median age at diagnosis was 76 years (interquartile range [IQR] 68-83) and 2,783 patients (63%) were male. Incidence rates (1 case/1,000,000 individuals) were as follows: overall 4.4, male 6.6, female 2.9, Non-Hispanic White 4.9, and Non-Hispanic Black 3.3. The incidence did not significantly change from 2004 to 2015. With a median follow up of 5.8 years (95% CI: 5.5-6.3), the median OS was 1.3 years (95% CI: 1.3-1.4). 3635 patients (82%) died. Among those who died, 2016 patients (55%) deaths were CMML-related. When comparing CMML patients to the US general population, 3,156 patients were matched to the expected survival tables. In the general U.S. population, the expected survival for 12, 24, 36, 48 and 60 months was 95.6%, 91.3%, 87.1%, 83.1%, and 79.2%, respectively. In contrast, the RS for patients with CMML at the same time points was 63.6%, 46.2%, 35.2%, 28.8%, and 23.1% (Figure 1). 229 patients (5.2%) progressed to AML. The median time to AML was 1.2 years (IQR 0.6-2.3). In NCDB (n=6403), the median age at diagnosis was 74 years (IQR 66-82). With the median follow up of 6 years (95% CI 3.5-9), the median OS was 1.3 years (95% CI 0.4-3.3). The distribution of CDS score 0, 1, and &amp;gt;1 was 4518 (71%), 1193 (18%), and 692 (11%) respectively. 4687 (77%) had government insurance, while 1399 (23%) had private insurance. 3750 (60%) were treated at a non-academic center. The year of diagnosis was associated with improved OS (HR 0.99, 95% CI: 0.98-0.99). Patients who were diagnosed in 2012-2015 had improved OS compared to patients diagnosed in 2004-2007 (HR 0.89, 95% CI 0.83-0.95) with OS at 1- and 5- years being 60% and 16% (2012-2015) vs. 56% and 17% (2008-2011) vs. 53% and 15% (2004-2007) respectively. 3029 (48%) patients received chemotherapy, while 270 (4%) patients received stem cell transplant as the first-line therapy. The median time to chemotherapy from diagnosis was 19 days (IQR 6-43). OS at 1-, 5-, and 10-years was 57%, 18%, and 4% (no chemotherapy), 56%, 14%, and 7% (received chemotherapy), 79%, 44%, and 38% (received stem cell transplant), and 56%, 15%, 5% (no stem cell transplant). OS curves are shown in Figure 2. Factors independently predicting inferior OS were age ≥ 65 years at the time of diagnosis (p&amp;lt;0.001), CDS ≥ 1 (p&amp;lt;0.001), government insurance (p&amp;lt;0.001), and treatment at a non-academic center (p&amp;lt;0.001) (Table). Conclusion: Despite an improvement in survival over the years, CMML continues to be a cause of significant morbidity and mortality. Older age, CDS ≥ 1, government insurance, and treatment at non-academic facilities were predictive of inferior survival. Disclosures Shah: Dren Bio: Consultancy.

MPN-379: Interim Results from an Ongoing Phase 1/2 Clinical Trial of Tagraxofusp, a CD123-Targeted Therapy, in Patients with Chronic Myelomonocytic Leukemia (CMML)

Background: Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder with overlapping features of myelodysplastic syndromes and myeloproliferative neoplasms (MDS/MPN) with poor outcomes, particularly in the relapsed/ refractory (R/R) setting. Current FDA-approved therapies have limited clinical impact. Clinical outcomes appear particularly poor in patients with proliferative features (high WBC counts, splenomegaly, high symptom burden) and high-risk cytogenetic and/or genomic features. Tagraxofusp (TAG) targets CD123, a biomarker expressed on CMML blasts and clonal monocytes; additionally, there is evidence of microenvironmental clonal plasmacytoid dendritic cells. Collectively, these features provide a rationale to assess the role of TAG in CMML patients. Objectives: To assess safety and efficacy of TAG in patients with CMML refractory/resistant/intolerant to HMAs, hydroxyurea, or intensive chemotherapy. Methods: Multicenter Phase 1/2 trial with TAG being administered as a daily IV infusion at 7, 9, or 12 mcg/kg on days 1–3 every 21 days (cycle 1-4), 28 days (cycles 5-7), and 42 days (cycles 8+) in stage 1 and 12 mcg/kg in stage 2. Results: Twenty-nine patients, including CMML-1 [n=19] and CMML-2 [n=10]; the median age was 70 years (range 42–87). Thirteen patients (45%) had baseline splenomegaly (spleen palpable below the left costal margin [BCM]); nine of these patients had baseline splenomegaly ≥5 cm BCM. The most common treatment-related adverse events (TRAEs, incidence ≥25%) were hypoalbuminemia, thrombocytopenia, and anemia. The most common ≥ grade 3 TRAEs were thrombocytopenia (34%), anemia (17%), and nausea (3%). Capillary leak syndrome was reported in seven patients (4 with grade 1–2; 3 with grade 3). Three patients, all with splenomegaly at baseline, achieved complete bone marrow responses (BMCRs), including one patient who was allografted in CR. Of note, two of these three BMCRs had proliferative CMML with high-risk cytogenetic and genomic features. Analysis of clinical benefit demonstrated a clinical reduction in splenomegaly in all patients with baseline splenomegaly (14/14): 71% (10/14) had spleen size reduction of ≥50%, and 60% (6/10) with baseline spleen size ≥5 cm had spleen size reduction of ≥50%. Conclusions: The interim results represent the clinical efficacy and safety of TAG monotherapy in a cohort of CMML patients, including patients with splenomegaly, a recognized poor prognostic factor in CMML. ( NCT02268253 )

Molecular Basis and Clinical Application of Growth-Factor-Independent In Vitro Myeloid Colony Formation in Chronic Myelomonocytic Leukemia.

We have originally reported that colony-forming units granulocyte/macrophage (CFU-GM) formation is an in vitro feature of chronic myelomonocytic leukemia (CMML) and a strong predictor for short survival. Elucidation of the molecular basis underlying this in vitro phenomenon could be helpful to define molecular features that predict inferior outcome in patients. We studied the correlation between the mutational landscape and spontaneous colony formation in 164 samples from 125 CMML patients. As compared to wildtype samples, spontaneous in vitro CFU-GM formation was significantly increased in samples containing mutations in NRAS, CBL and EZH2 that were confirmed as independent stimulatory factors by multiple regression analysis. Inducible expression of mutated RAS but not JAK2 was able to induce growth factor independence of Ba/F3 cells. Whereas high colony CFU-GM growth was a strong unfavorable parameter for survival (p < 0.00001) and time to transformation (p = 0.01390), no single mutated gene had the power to significantly predict for both outcome parameters. A composite molecular parameter including NRAS/CBL/EZH2, however, was predictive for inferior survival (p = 0.00059) as well as for increased risk of transformation (p = 0.01429). In conclusion, we show that the composite molecular profile NRAS/CBL/EZH2 derived from its impact on spontaneous in vitro myeloid colony formation improves the predictive power over single molecular parameters in patients with CMML.

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

BackgroundChronic 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.MethodsWe 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.FindingsWe 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.InterpretationOur 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.FundingProject funding was supported by Oglesby Charitable Trust, Cancer Research UK, Blood Cancer UK, and UK Medical Research Council.

Leukaemia cutis as a specific skin involvement in chronic myelomonocytic leukaemia and review of the literature: Acknowledgments.

The skin involvement of myeloid leukaemia is conventionally divided into specific malignant lesions and non-specific benign lesions, and these categories are also applicable in chronic myelomonocytic leukaemia (CMML). According to the 2016 World Health Organization (WHO) classification of tumours of haematopoietic and lymphoid tissues, CMML is defined as a myeloid neoplasm with characteristics of myelodysplastic syndrome (MDS) and myeloproliferative neoplasms (MPNs). As a specific cutaneous sign of extramedullary infiltration, leukaemia cutis (LC) is a rare occurrence in patients with CMML, and only approximately 89 cases have been reported in the literature thus far. The clinical features of LC are varied, and LC in CMML exhibits heterogeneous histopathologic features, with manifestations as cutaneous nodules or papules that are composed of blast cells showing either granulocytic or monocytic differentiation. Skin biopsy and further immunohistochemical examination are essential at the time of diagnosis to evaluate pathological type and determine the clinical course. Generally, once diagnosed as LC in CMML, this unusual skin lesion might be an indicator of transformation to acute myeloid leukaemia (AML) and is associated with a poor prognosis. The main treatment is allogeneic stem cell transplantation (ASCT). Therefore, early diagnosis and accurate identification have important therapeutic and prognostic significance in CMML patients with skin infiltration.

Clinical, Hematologic, Biologic and Molecular Characteristics of Patients with Myeloproliferative Neoplasms and a Chronic Myelomonocytic Leukemia-Like Phenotype

Patients with a myeloproliferative neoplasm (MPN) sometimes show a chronic myelomonocytic leukemia (CMML)-like phenotype but, according to the 2016 WHO classification, a documented history of an MPN excludes the diagnosis of CMML. Forty-one patients with an MPN (35 polycythemia vera (PV), 5 primary myelofibrosis, 1 essential thrombocythemia) and a CMML-like phenotype (MPN/CMML) were comprehensively characterized regarding clinical, hematologic, biologic and molecular features. The white blood cell counts in MPN/CMML patients were not different from CMML patients and PV patients. The hemoglobin values and platelet counts of these patients were higher than in CMML but lower than in PV, respectively. MPN/CMML patients showed myelomonocytic skewing, a typical in vitro feature of CMML but not of PV. The mutational landscape of MPN/CMML was not different from JAK2-mutated CMML. In two MPN/CMML patients, development of a CMML-like phenotype was associated with a decrease in the JAK2 V617F allelic burden. Finally, the prognosis of MPN/CMML (median overall survival (OS) 27 months) was more similar to CMML (JAK2-mutated, 28 months; JAK2-nonmutated 29 months) than to PV (186 months). In conclusion, we show that patients with MPN and a CMML-like phenotype share more characteristics with CMML than with PV, which may be relevant for their classification and clinical management.

Correlation of RAS-Pathway Mutations and Spontaneous Myeloid Colony Growth with Progression and Transformation in Chronic Myelomonocytic Leukemia-A Retrospective Analysis in 337 Patients.

Although the RAS-pathway has been implicated as an important driver in the pathogenesis of chronic myelomonocytic leukemia (CMML) a comprehensive study including molecular and functional analyses in patients with progression and transformation has not been performed. A close correlation between RASopathy gene mutations and spontaneous in vitro myeloid colony (CFU-GM) growth in CMML has been described. Molecular and/or functional analyses were performed in three cohorts of 337 CMML patients: in patients without (A, n = 236) and with (B, n = 61) progression/transformation during follow-up, and in patients already transformed at the time of sampling (C, n = 40 + 26 who were before in B). The frequencies of RAS-pathway mutations (variant allele frequency ≥ 20%) in cohorts A, B, and C were 30%, 47%, and 71% (p < 0.0001), and of high colony growth (≥20/105 peripheral blood mononuclear cells) 31%, 44%, and 80% (p < 0.0001), respectively. Increases in allele burden of RAS-pathway mutations and in numbers of spontaneously formed CFU-GM before and after transformation could be shown in individual patients. Finally, the presence of mutations in RASopathy genes as well as the presence of high colony growth prior to transformation was significantly associated with an increased risk of acute myeloid leukemia (AML) development. Together, RAS-pathway mutations in CMML correlate with an augmented autonomous expansion of neoplastic precursor cells and indicate an increased risk of AML development which may be relevant for targeted treatment strategies.

Impact of splenomegaly on outcomes of allogeneic hematopoietic stem cell transplantation in patients with chronic myelomonocytic leukemia

目的探讨脾肿大对慢性粒-单核细胞白血病（CMML）异基因造血干细胞移植（allo-HSCT）预后的影响。方法对2004年至2018年在北京大学血液病研究所接受allo-HSCT后的25例CMML患者进行回顾性分析，根据预处理前2周是否伴有脾脏肿大分为脾肿大组和非脾肿大组，比较两组患者在植入、移植物抗宿主病（GVHD）、复发以及生存方面的差异。结果①脾肿大组15例（男8例，女7例），中位年龄45（23~61）岁；非脾肿大组10例（男、女各5例），中位年龄39（12~56）岁。两组患者基线特征差异无统计学意义（P>0.05）。②脾肿大组、非脾肿大组粒细胞植入率分别为93.3%（14/15）、100.0%（10/10），中位植入时间分别为17（11~20）d、14（11~18）d（χ2=5.303，P=0.021）；脾肿大组、非脾肿大组血小板植入率分别为80.0%（12/15）、90.0%（9/10）（P=0.212），中位植入时间分别为17（12~33）d、15（12~19）d（χ2=0.470，P=0.493）。③脾肿大组5例发生急性GVHD（Ⅰ/Ⅱ度4例，Ⅲ/Ⅳ度1例），非脾肿大组6例发生急性GVHD（Ⅰ/Ⅱ度5例，Ⅲ/Ⅳ度1例）（χ2=0.204，P=0.652）。脾肿大组、非脾肿大组移植后100 d的急性GVHD累积发生率分别为33.3%（95%CI 14.9%~51.7%）、20.0%（95%CI 2.8%~37.2%）（P=0.635）。脾肿大组5例发生慢性GVHD（广泛型3例），非脾肿大组未发生慢性GVHD（P=0.041）。④脾肿大组、非脾肿大组3年累积复发率分别为（42.7±2.6）%、（11.1±1.2）%（χ2=1.824，P=0.122），3年总生存率分别为（61.5±13.5）%、（68.6±15.1）%（χ2=0.351，P=0.554），3年无白血病生存率分别为（56.3±14.8）%、（80.0±17.9）%（χ2=1.148，P=0.284）。结论脾肿大可致CMML患者allo-HSCT后粒细胞植入延迟，对生存及复发无影响。

LILRB4 expression in chronic myelomonocytic leukemia and myelodysplastic syndrome based on response to hypomethylating agents

LILRB4 is expressed in AML M4/M5 cells and negatively regulates immune cell activation via T-cell suppression. Its expression and role in chronic myelomonocytic leukemia (CMML) and myelodysplastic syndrome (MDS) are unknown. We investigated LILRB4 expression in 19 CMML and 27 MDS patients and correlated it with response to subsequent hypomethylating agent (HMA) therapy. LILRB4 RNA expression was increased in CMML patients when compared to MDS patients and healthy controls (q < 0.1) and slightly increased in patients who responded to HMAs (q > 0.1). Pathway analysis revealed upregulation of PD-1 signaling, CTLA-4 signaling, and inflammatory response, and gene correlates were positively associated with CTLA-4 expression. Given current modest results with immunotherapy in myeloid malignancies, further investigation of LILRB4 as an immune checkpoint inhibitor target is needed. With the positive correlation between LILRB4 and CTLA-4 expression, combining anti-LILRB4 and anti-CTLA-4 agents may be a novel therapeutic approach in myeloid malignancies that warrants larger studies.

Chronic Myelomonocytic leukemia: 2020 update on diagnosis, risk stratification and management.

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder with overlapping features of myelodysplastic syndromes and myeloproliferative neoplasms, with an inherent risk for leukemic transformation (~15% over 3-5 years). Diagnosis is based on the presence of sustained (>3 months) peripheral blood monocytosis (≥1 × 109 /L; monocytes ≥10%), along with bone marrow dysplasia. Clonal cytogenetic abnormalities occur in ~ 30% of patients, while >90% have gene mutations. Mutations involving TET2 (~60%), SRSF2 (~50%), ASXL1 (~40%) and the oncogenic RAS pathway (~30%) are frequent; while the presence of ASXL1 and DNMT3A mutations and the absence of TET2 mutations negatively impact over-all survival. Molecularly integrated prognostic models include; the Groupe Français des Myélodysplasies (GFM), Mayo Molecular Model (MMM) and the CMML specific prognostic model (CPSS-Mol). Risk factors incorporated into the MMM include presence of nonsense or frameshift ASXL1 mutations, absolute monocyte count>10 × 109 /L, hemoglobin <10 g/dL, platelet count <100 × 109 /L and the presence of circulating immature myeloid cells. The MMM stratifies CMML patients into four groups; high (≥3 risk factors), intermediate-2 (2 risk factors), intermediate-1 (1 risk factor) and low (no risk factors), with median survivals of 16, 31, 59 and 97 months, respectively. Hypomethylating agents such as 5-azacitidine and decitabine are commonly used, with overall response rates of ~40%-50% and complete remission rates of ~7%-17%; with no impact on mutational allele burdens. Allogeneic stem cell transplant is the only potentially curative option, but is associated with significant morbidity and mortality.

Epigenetic therapy of myelodysplastic syndromes connects to cellular differentiation independently of endogenous retroelement derepression

BackgroundMyelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML) are characterised by abnormal epigenetic repression and differentiation of bone marrow haematopoietic stem cells (HSCs). Drugs that reverse epigenetic repression, such as 5-azacytidine (5-AZA), induce haematological improvement in half of treated patients. Although the mechanisms underlying therapy success are not yet clear, induction of endogenous retroelements (EREs) has been hypothesised.MethodsUsing RNA sequencing (RNA-seq), we compared the transcription of EREs in bone marrow HSCs from a new cohort of MDS and chronic myelomonocytic leukaemia (CMML) patients before and after 5-AZA treatment with HSCs from healthy donors and AML patients. We further examined ERE transcription using the most comprehensive annotation of ERE-overlapping transcripts expressed in HSCs, generated here by de novo transcript assembly and supported by full-length RNA-seq.ResultsConsistent with prior reports, we found that treatment with 5-AZA increased the representation of ERE-derived RNA-seq reads in the transcriptome. However, such increases were comparable between treatment responses and failures. The extended view of HSC transcriptional diversity offered by de novo transcript assembly argued against 5-AZA-responsive EREs as determinants of the outcome of therapy. Instead, it uncovered pre-treatment expression and alternative splicing of developmentally regulated gene transcripts as predictors of the response of MDS and CMML patients to 5-AZA treatment.ConclusionsOur study identifies the developmentally regulated transcriptional signatures of protein-coding and non-coding genes, rather than EREs, as correlates of a favourable response of MDS and CMML patients to 5-AZA treatment and offers novel candidates for further evaluation.

Phenotypic Correlates and Prognostic Outcomes of TET2 Mutations in Myelodysplastic Syndrome/Myeloproliferative Neoplasm Overlap Syndromes: A Comprehensive Study of 504 Patients

Introduction: Myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) overlap syndromes consist of 5 distinct WHO-defined entities; namely chronic myelomonocytic leukemia (CMML), atypical chronic myeloid leukemia, BCR/ABL1- (aCML), juvenile myelomonocytic leukemia (JMML), MDS/MPN with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T), and MDS/MPN, unclassifiable (MDS/MPN-U) (Arber et al., Blood 2016). With the notable exception of JMML, a bona fide RASopathy, the other entities are characterized by clinical heterogeneity and molecular diversity. Loss of function TET2 mutations (TET2MT) are common in myeloid neoplasms, especially CMML (60%), and are known leukemogenic drivers. We carried out this study to assess the TET2 mutational landscape and phenotypic correlates in patients with MDS/MPN overlap syndromes. Methods: After approval by the institutional review board, adult patients with WHO defined MDS/MPN overlap syndromes were included; with the exception of JMML. The BM morphology, cytogenetics and 2016, WHO-diagnoses were retrospectively reviewed and all patients underwent targeted next generation sequencing for 29 myeloid-relevant genes, obtained on BM mononuclear cells, at diagnosis, or at first referral, by previously described methods (Patnaik et al., BCJ 2016). Results: Five hundred and four patients were included in the study; including 387 (77%) with CMML, 48 (10%) with MDS/MPN-RS-T, 17 (3%) with aCML and 52 (10%) with MDS/MPN-U. The median age at diagnosis was 71 (range, 18-99) years, and 333 (66%) were male. TET2MT were seen in 212 (42%) patients, with the frequency of other mutations being: ASXL1 45%, SRSF2 40%, NRAS 15%, SF3B1 13%, CBL, RUNX1 and SETBP1 12% each, and JAK2 V617F 11% (Figure B). Among the MDS/MPN overlap syndromes, TET2 was more frequently mutated in CMML (49%) and aCML (47%) compared to MDS/MPN-RS-T (10%) and MDS/MPN-U (15%). The prevalence of patients with TET2MT increased with age, a finding consistent across all MDS/MPN subtypes (Figure C). Overall, 341 TET2MT were identified in 212 patients (mean 1.6 variants/patient, range 0-5): 120 (24%) had &gt;1 TET2MT, while 113 (22%), 5 (1%) and 2 (0.4%) had 2, 3 and 5 mutations, respectively. CMML and aCML patients were more likely to have an age-independent increase in multiple TET2MT (28% and 24%), in comparison to MDS/MPN-RS-T (4%) and MDS/MPN-U (8%). TET2 MT spanned the entire coding sequence and were mostly truncating (78%, Figure A): 59 (17%) were missense, 14 (4%) involved the splice-donor/acceptor sites, 2 (0.5%) were in-frame deletions, 129 (38%) were nonsense, and 137 (40%) were frameshift mutations. Overall, the distribution of TET2MT was superimposable across CMML, aCML, and MDS/MPN-U; the only exception being the absence of splice site mutations in the latter two. One hundred and eighty-seven (55%) TET2MT were secondary to pathogenic single nucleotide variants (SNV), while the remainders were secondary to deletions (25%) and insertions (15%). Transitions comprised the most frequent type of SNV (65%), with the C:G&gt;T:A being the most common (56%). Patients with MDS/MPN overlap syndrome and TET2MT were more likely to have additional gene mutations compared to wild type patients (mean mutation number 3.1 vs 2.1, p&lt;0.0001), with common co-mutations being SRSF2 (51%), ASXL1 (42%), and CBL (17%). The median overall survival (OS) of the entire cohort was 29 (range, 0-170) months; 29 months for CMML, 63 months for MDS/MPN-RS-T, 14 months for aCML, and 25 months for MDS/MPN-U. On univariate analysis, OS was superior in CMML patients with TET2MT (35 months) compared to wild type cases (21 months, p&lt;0.0001, Figure D), and in CMML patients with &gt;1 TET2MT (41 months) in comparison to wild type (21 months, p&lt;0.0001) and single TET2MT (29 months, p=0.0476) cases (Figure E). These observations were not seen in patients with aCML, MDS/MPN-RS-T, and MDS/MPN-U. Conclusion: Our study demonstrates that TET2MT are among the most frequent mutations in patients with MDS/MPN overlap syndromes (42%), especially CMML (49%), with an age-dependent increase in the frequency and number of TET2MT. Mutations in TET2 were found to span the entire coding sequence, with truncating mutations being more common (78%). Importantly, in CMML, TET2MT, including number of TET2MT, were associated with favorable survival outcomes. Figure Disclosures Al-Kali: Astex Pharmaceuticals, Inc.: Research Funding. Patnaik:Stem Line Pharmaceuticals.: Membership on an entity's Board of Directors or advisory committees.

The Absolute Count of Circulating, Classical, CD14++/CD16- Monocytes Is a Poor Prognosis Marker in Chronic Myelomonocytic Leukemia (CMML)

Introduction A relative increase in classical monocyte fraction (cMo, CD14++CD16-) over 94% of total peripheral blood monocytes, as measured by flow cytometry, distinguishes a CMML from a reactive monocytosis with a 94.1% specificity and a 92.8% sensitivity (Selimoglu-Buet, 2015; Talati, 2017; Patnaik, 2017; Selimoglu-Buet, 2017; Hudson, 2018). This phenotype is independent of the absolute monocyte count, WHO subtype of CMML, its dysplastic (MD) vs proliferative (MP) feature and its mutational background. The limitation of this diagnostic tool is the changes in monocyte subset repartition induced by an associated inflammatory disease that increase the fraction of intermediate monocytes (iMo, CD14++CD16+), leading to underestimation of cMo accumulation (Selimoglu-Buet, 2017). The present study explores the prognostic significance of cMo accumulation in CMML. Patients and methods Among CMML patients (diagnosis according to 2016 WHO criteria) included in our previous studies, we selected patients diagnosed from June 2012 to March 2017 in four centers in which follow-up was actualized in June 2019. Disease was classified according to WHO 2016 (CMML-0, -1, -2 and MP vs MD subtypes). When possible, the CMML Prognostic Scoring System (CPSS) was calculated. Peripheral blood flow cytometry data were reanalyzed in a blind fashion by a skilled operator. Inflammatory CMML were defined by a cMo percentage &lt;94% associated with a bulbous aspect on flow cytometry profile (Figure 1A). The absolute cMo count in the peripheral blood was determined by combining flow cytometry measurement of cMo fraction and the total monocyte count provided by Complete Blood Count. Results One hundred and twenty-nine CMML patients (mean age: 75±10 years, sex ratio: 2.2) were classified into 53 CMML-0 (41%), 58 CMML-1 (45%) and 18 CMML-2 (14%) with 97 dysplastic forms (75%). Eight patients (6%) having received DNA damaging therapies (radiations or chemotherapies) were considered as secondary CMML. Eleven patients (9%) had evolved from a previous myelodysplastic syndrome. The median white blood count, hemoglobin level and platelet count were 9 G/l (IQR: 5.9-12.9), 11.8 g/dl (IQR: 9.7-13.1), and 121 G/l (IQR: 73-212), respectively. The CPSS score, calculated in 119 cases, classified the patients into "Low" (n=55), "Intermediate-1" (n=33), "Intermediate-2 (n=29) and "High" (n=2) categories. Twenty of the 114 patients (18%) with available follow-up (median duration: 26.7 months [13.9-36.5]) had received hypomethylating agents and 3 (3%) were allografted. A cMo percentage above the threshold (97.0% [IQR: 96.3-98.1]) was detected in 112 patients (87%) whereas 17 (13%), referred thereafter as "inflammatory CMML", displayed cMo&lt;94% (91.6% [IQR: 89.9-93.2], p&lt;0.001) with an inflammatory state (C-reactive protein: 8 mg/L [IQR: 3.1-20.2] (Figure 1B). Importantly, the absolute count of cMo was similar in inflammatory (1.6 G/l [IQR: 1.1- 1.8]) and classical (1.7 G/l [IQR: 1.2- 2.6], p=0.25) CMML (Figure 1C). Focusing on total monocyte and cMo absolute counts, we did not detect any significant difference between CMML-0, CMML-1 and CMML-2. While cMo percentages were similar in MP and MD subtypes, the total monocyte (6.0 ±6.0 G/l vs 1.7 ±0.7 G/L, p&lt;0.001) and the cMo (5.8 ±5.7 G/L vs 1.6 ±0.7 G/L, p&lt;0.001) counts were increased in MP compared to MD CMML. A poor prognosis CPSS score at diagnosis also correlated with an increase in the absolute cMo count ("Intermediate-2 or High": 4.5 ±6.0 G/L vs "Low or Intermediate-1": 2.0 ±1.7 G/L; p &lt;0.001) (Figure 1D). A Receiver Operator Curve (ROC) defined a cut-off value of 2.0 G/L to identify patients with poorest outcome. Indeed, CMML patients with an absolute cMO count ≥2.0 G/L at diagnosis had a higher risk to progress to acute myeloid leukemia (AML) (HR=0.34 [95% CI, 0.12 - 0.91]) (Figure 1E). Eventually, patients with an absolute cMO count ≥2.0 G/L at diagnosis had poorer overall survival (OS) compared with patients with a lower absolute cMO count (HR=0.42 [95% CI, 0.22 - 0.80]; median OS: 31.9 months vs not reached, p=0.009) (Figure 1F). Conclusion These results demonstrate that in CMML patients, regardless of the relative cMo percentage, a high absolute count of circulating cMo at diagnosis ≥2.0 G/L correlates with a poor outcome, including a higher risk of AML progression and shorter survival. Figure 1 Disclosures Fenaux: Jazz: Honoraria, Research Funding; Celgene Corporation: Honoraria, Research Funding; Astex: Honoraria, Research Funding; Aprea: Research Funding. Wagner Ballon:Alexion: Consultancy, Honoraria.