Itzykson, Raphaël

PURPOSE Chronic myelomonocytic leukemia (CMML) is a rare myeloid neoplasm characterized by clinical heterogeneity and is associated with poor outcomes. To date, limited molecular information has been incorporated into disease classification and risk stratification. We aimed to integrate genomic features into the clinical decision-making process for CMML. PATIENTS AND METHODS We analyzed a retrospective cohort of 3013 patients with CMML (training set) and a prospective population of 516 patients (validation set). Using an innovative framework for multimodal data analysis, we developed molecular-based disease taxonomy and prognostication. RESULTS Unsupervised clustering identified nine entities with distinct genomic features and outcomes ( P < .001), including splicing machinery, transcription factors, signal transduction and tyrosine kinase pathways aberrations, and high-risk molecular signatures. Notably, 15% of patients showed molecular/clinical overlap with other myeloid neoplasms. We integrated molecular and clinical information to build the international CMML Prognostic Scoring System (iCPSS), incorporating mutations in nine genes together with hematologic parameters and cytogenetic abnormalities. The iCPSS identified five groups with distinct probability of overall and leukemia-free survival in both training and validation cohorts ( P < .001), outperforming existing prognostic models. Importantly, 55% of patients were reassigned to higher or lower risk groups by the iCPSS. Decision analysis demonstrated that iCPSS could refine the optimal timing of allogeneic transplantation at the individual level; compared with conventional prognostic tools, iCPSS-based decision modeling changed transplantation strategy in 31% of cases, resulting in a significant gain-in-life expectancy for eligible patient population ( P < .001). A federated learning platform was implemented to enable continuous, privacy-preserving model update across multiple centers. CONCLUSION Molecular information improves CMML classification and prognostication, supports more effective clinical decision making, and potentially refines the design of clinical trials.

Background. Study of myeloid neoplasms (MN) has been rapidly transformed by genome characterization. Gene mutations have been reported to influence disease phenotype and risk of disease progression, and the evaluation of mutational status can provide valuable insights to improve the decision-making process. In this international study, we evaluated the clinical impact of mutational screening in patients with CMML, which is characterized by significant clinical and genomic heterogeneity, including a substantial proportion of patients with poor outcomes and unmet needs. Currently, only limited molecular information has been incorporated into CMML classification and prognostication. Methods. We retrospectively collected 3182 CMML patients. We used MOSAIC, an AI-based framework for multimodal analysis in rare cancers (PMID: 38875514) to develop innovative, molecular-based tools for classification and prognostication. An independent validation of the results on 516 prospectively collected patients was performed. Results. Bayesian Networs and Hierarchical Dirichlet Processes were used to identify genomic associations and define a CMML molecular classification. We identified 11 clusters with distinct clinical and genomic features, including splicing machinery, signal transduction and tyrosine kinase pathways aberrations, and high-risk molecular signatures (i.e., AML-like and TP53 mutations). Up to 15% of patients showed clear genomic overlap with other MN. Importantly, extensive multi-color flow cytometry on T lymphocytes, NK and myeloid cells (BD FACSymphony A5 Cell Analyzer) revealed specific immunologic and inflammation signatures associated with molecular subgroups. We then integrated molecular and clinical information to build an international CMML Prognostic Scoring System (iCPSS). We assessed the performance of different statistical and AI-based methods; L1-penalized Cox Model resulted as the best performing method. Selected features included hematological parameters (WBC, Hb, PLT and marrow blasts), cytogenetic abnormalities, and mutations in 10 genes (ASXL1, DNMT3A, EZH2, NRAS, RUNX1, SETBP1, STAG2, TET2, TP53, U2AF1). By Bayesian thresholds optimization, we identified 5 risk classes (i.e., very-low, low, intermediate, high and very-high) with median overall survival (OS) ranging from 99 to 9 months (P&lt;.001), and median leukemia-free survival (LFS) ranging from 210 to 18 months (P&lt;.001). iCPSS provided better patient discrimination across all clinical endpoints compared to currently available prognostic tools, with a Concordance Index (CI) for OS of 0.75 versus 0.62-0.64, respectively. Notably, compared to available scoring systems, up to 40% of patients were reassigned to higher or lower risk classes by the iCPSS. External validation on an independent prospective cohort confirmed that the performance of iCPSS is superior to existing prognostic models (CI for OS 0.71 vs 0.54-0.61, respectively) To demonstrate the clinical utility of iCPSS, we focused on 753 patients who underwent allogeneic stem cell transplantation (HSCT). In multivariable analysis, iCPSS stratified the probability of OS post-HSCT (P&lt;.001) and identified groups of patients with different probabilities of disease relapse, ranging from 9% to 62% (P&lt;.001). We employed a clinical- and genomic-based decision support system (PMID: 38723212) to determine the optimal timing of HSCT. Preliminary analyses indicated that higher-risk patients according to iCPSS (i.e., intermediate, high, and very high) benefit from an immediate HSCT strategy. Lower-risk patients (i.e., very low and low) had life expectancy maximized with delayed HSCT. Modeling decision analysis using iCPSS compared to conventional scores, resulted in a change in transplantation policy for a significant proportion of patients (up to 25%). Conclusion. Molecular information significantly improves the classification of CMML patients, providing a basis for refining diagnostic boundaries with other MN and for a more rational inclusion of patients in clinical trials. The iCPSS demonstrated superior performance over currently available scoring systems and improved HSCT decision making process.

Chronic myelomonocytic leukemia (CMML) is a severe myeloid malignancy with limited therapeutic options. Single-cell analysis of clonal architecture demonstrates early clonal dominance with few residual WT hematopoietic stem cells. Circulating myeloid cells of the leukemic clone and the cytokines they produce generate a deleterious inflammatory climate. Our hypothesis is that therapeutic control of the inflammatory component in CMML could contribute to stepping down disease progression. The present study explored the contribution of immature granulocytes (iGRANs) to CMML progression. iGRANs were detected and quantified in the peripheral blood of patients by spectral and conventional flow cytometry. Their accumulation was a potent and independent poor prognostic factor. These cells belong to the leukemic clone and behaved as myeloid-derived suppressor cells. Bulk and single-cell RNA-Seq revealed a proinflammatory status of iGRAN that secreted multiple cytokines of which CXCL8 was at the highest level. This cytokine inhibited the proliferation of WT but not CMML hematopoietic stem and progenitor cells (HSPCs) in which CXCL8 receptors were downregulated. CXCL8 receptor inhibitors and CXCL8 blockade restored WT HSPC proliferation, suggesting that relieving CXCL8 selective pressure on WT HSPCs is a potential strategy to slow CMML progression and restore some healthy hematopoiesis.

Abstract Drug development for chronic myelomonocytic leukemia (CMML) has failed to parallel the recent success observed in related myeloid neoplasms. To address these shortcomings, the US Food and Drug Administration (FDA) held a “Mini-symposium on CMML: Current State of the Art and Trial Design” in September 2023. This symposium brought together a panel of key FDA regulators and academic experts in CMML drug development to discuss challenges and provide perspectives on future drug development for this disease. The panel explored unique challenges that underlie the lack of therapeutic advances in CMML to date and discussed relevant topics such as clinical trial design, study end points, and key regulatory considerations. This article summarizes the key points of discussion from this symposium to facilitate advancements in the field.

Abstract To determine the survival benefit of allogeneic hematopoietic cell transplantation (allo-HCT) in chronic myelomonocytic leukemias (CMML), we assembled a retrospective cohort of CMML patients 18-70 years old diagnosed between 2000 and 2014 from an international CMML dataset (n = 730) and the EBMT registry (n = 384). The prognostic impact of allo-HCT was analyzed through univariable and multivariable time-dependent models and with a multistate model, accounting for age, sex, CMML prognostic scoring system (low or intermediate-1 grouped as lower-risk, intermediate-2 or high as higher-risk) at diagnosis, and AML transformation. In univariable analysis, lower-risk CMMLs had a 5-year overall survival (OS) of 20% with allo-HCT vs 42% without allo-HCT (P &lt; .001). In higher-risk patients, 5-year OS was 27% with allo-HCT vs 15% without allo-HCT (P = .13). With multistate models, performing allo-HCT before AML transformation reduced OS in patients with lower-risk CMML, and a survival benefit was predicted for men with higher-risk CMML. In a multivariable analysis of lower-risk patients, performing allo-HCT before transformation to AML significantly increased the risk of death within 2 years of transplantation (hazard ratio [HR], 3.19; P &lt; .001), with no significant change in long-term survival beyond this time point (HR, 0.98; P = .92). In higher-risk patients, allo-HCT significantly increased the risk of death in the first 2 years after transplant (HR 1.46; P = .01) but not beyond (HR, 0.60; P = .09). Performing allo-HCT before AML transformation decreases life expectancy in lower-risk patients but may be considered in higher-risk patients.

Background: Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) in adult populations include several rare hematologic malignancies with similar clinicopathologic features that have a significant impact on patient QOL and lead to increased risk of infection, hemorrhage, anemia and transformation to AML (e.g. CMML, aCML, MDS/MPN-RST, and MDS/MPN-U). The only approved therapies for any of the MDS/MPNs are DNA methyltransferase inhibitors (DNMTis) for patients (pts) with CMML. Due to both the rarity and the heterogeneity of MDS/MPNs, it has been challenging to study in dedicated, prospective studies and thus refining treatment strategies has been difficult and optimal salvage treatments in pts who fail DNMTis have also not been rigorously studied. ABNL-MARRO (A Basket study of Novel therapy for untreated MDS/MPN and Relapsed/Refractory Overlap Syndromes) is an international cooperation providing the framework for clinical trials for MDS/MPN, and explore clinical-pathologic biomarkers. Study Design and Methods: The first study within ABNL-MARRO, ABNL MARRO 001 (AM-001), is an open label, randomized phase 1-2 study that will test 3 novel oral treatment combinations in MDS/MPNs, with each of 3 treatment arms including a novel targeted agent and ASTX727, a fixed dose combination of the DNMTi decitabine and the cytidine deaminase inhibitor cedazuridine to improve decitabine oral bioavailability. The novel agents combined with ASTX727 are: a selective JAK1 inhibitor itacitinib, pan PIM inhibitor INCB053914 and LSD1 inhibitor, INCB059872. Each combination will be tested first in a safety run-in (Phase 1b) to determine the RP2D and schedule of each combination therapy using a 3+3 de-escalation design, and a maximum of four dose decrements will be allowed. After the RP2D and schedule has been determined for a given novel drug combination, efficacy of that combination therapy in MDS/MPN pts will then be evaluated in phase 2 using a Simon's Two-Stage design to allow early discontinuation of any futile treatment regimen and to pursue potentially beneficial combinations in larger cohorts of pts. While each of the targeted agents either has undergone or is currently undergoing safety testing in combination with the DNMTi in myeloid diseases, clear rates of expected responses in MDS/MPN are not known. Retrospective studies of DAC or AZA reveal overall response rates (ORR) from 10-56% in CMML (Helbig et al, 2019; Duchman et al, 2018; Coston et al, 2019). The ORR from the ASTX727 single agent phase I study was 30%, but this included only 14% CMML (remainder MDS pts) and 45% of pts with previous treatment with AZA or DAC (Savona et al, 2019). Finally, and importantly, there are insufficient clinical trial data available for pts non-CMML MDS/MPN syndromes. Thus, the criteria for the Simon's Two-Stage design for each arm are based on best estimation from results of above studies. Accordingly, the null hypothesis that the ORR, as per the MDS/MPN Proposed Response Criteria (Savona et al, 2015; combined CR+MR+PR+Clinical benefit - CB), is 35%, will be tested against a one-sided alternative. In the first stage, 14 DNMTI-treatment naïve (TN) pts will be accrued in each AM-001 Arm and will receive treatment at the RP2D and schedule of the novel targeted agent and of ASTX727, as determined in the phase 1. If there are 5 or fewer responses in these 14 pts before the 7th cycle of therapy, the Arm will be stopped for futility. Otherwise, 30 additional pts (including both TN subjects and subjects relapsed after/refractory to other DNMTI-containing therapies) will be accrued for a total of 44. The null hypothesis will be rejected if 21 or more responses are observed in 44 pts before the 7th cycle of therapy. This design yields a type I error rate of 0.05 and power of 80% when the true response rate is 55%. The probability of early termination and expected sample size of any arm is 64% and 25 pts, respectively, assuming low (35% RR) efficacy Beyond the primary objectives of the study to evaluate the safety and efficacy of novel treatment combinations in MDS/MPN, the study will establish the ABNL MARRO infrastructure that leverages the expertise of the MDS/MPN international working group (IWG) for future prospective studies; will forge innovative scientific research that will improve our understanding of pathogenetic etiologies; and will inform the clinical application of diagnosis, risk stratification tools, and response assessments in MDS/MPNs. Disclosures Savona: AbbVie: Membership on an entity's Board of Directors or advisory committees; Sunesis: Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Selvita: Membership on an entity's Board of Directors or advisory committees; Karyopharm Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Patents & Royalties. Fenaux:Aprea: Research Funding; Jazz: Honoraria, Research Funding; Astex: Honoraria, Research Funding; Celgene Corporation: Honoraria, Research Funding. Padron:Incyte: Research Funding. Patnaik:Stem Line Pharmaceuticals.: Membership on an entity's Board of Directors or advisory committees. Platzbecker:Abbvie: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Sanz:Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Boehringer-Ingelheim: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Helsinn Healthcare: Membership on an entity's Board of Directors or advisory committees, Research Funding; Hoffman - La Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen - Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Onconova: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Santini:Menarini: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Acceleron: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Honoraria. OffLabel Disclosure: ASTX727, LSD1 inh, PIM inh, JAK1 inh in MDS/MPN

Background: CMML is a heterogeneous disease with overlapping features of MDS and MPN. Several risk scores have been proposed in CMML, including CPSS (Such Blood 2013) that identifies 4 risk groups (low, intermediate-1 [int-1], int-2 and high risk) with median overall survival (OS) ranging from 12 months to > 5 years. HSCT is the only curative treatment in CMML, with an expected 20-40% post-transplantation OS. Current guidelines, common to MDS and CMML recommend rapidly transplanting higher-risk CMML and delaying transplant in lower-risk disease (de Witte Blood 2017). Retrospective transplant studies have shown better outcome in lower-risk CMML (Liu et al BBMT 2017). Whether this translates into a survival benefit compared to a delayed transplant strategy requires prospective studies. Multistate models based on retrospective data from transplant and non-transplant patients (pts) have addressed similar issues in MDS (Koreth JCO 2013, Della Porta Leukemia 2017). Through a large collaborative study, we address the question of optimal timing for HSCT in CMML patients through a similar large international collaborative study. Method: We retrospectively selected pts from 2 registries: International MDS/MPN Working Group (IWG cohort, Padron Blood Cancer J 2015) and EBMT with the following criteria: WHO-defined CMML, age ≤ 70y, ECOG 0-2, diagnosis after 2000, available CPSS at the time of diagnosis. Different states were considered in higher- (CPSS int-2 and high) and lower- risk (CPSS low/int-1) pts: diagnosis, AML transformation, transplantation and death. IWG data was used to estimate transition probabilities from diagnosis to AML, transplantation and death and from AML to transplantation and death. EBMT data was used for transplantation to death transitions (Figure 1). Results: 719 and 403 pts were identified in the IWG and EMBT registry, respectively (resp). Median age was 64 (range 16-70) in IWG and 58 (19-70) years in EBMT cohort. Patients were male in 69% and 67% of IWG and EBMT cohorts, respectively (resp). CPSS was low in 22% and 13%, int-1 in 31% and 31%, int-2 in 40% and 45% and high in 8% and 11% of the IWG and EBMT pts, resp. In the IWG cohort, the 1 year cumulative incidence of transformation into AML were 7.3% and 18.2% in lower and higher risk patients, resp. Among the 719 pts from IWG, 102 received HSCT. At the time of diagnosis the expected life time of higher risk (int-2 and high) patients was 25.2 months while it was 44.1 months in lower risk (int-1 and low) patients. Table 1 reports gain or loss in expected life time (until 60 months after diagnosis) for transplantation at different intervals from diagnosis (within 6, 12, 18 and 24 months) for patients who have survived and not transformed to AML until the prediction time point, taking into account CPSS at diagnosis. Expected life time is also given separately for higher risk pts after transformation into AML. There was a modest gain of life expectancy with transplantation in higher risk patients (CPSS int-2 and high) while it was not the case in lower risk patients. The survival gain in higher risk pts with HSCT rose from 1.11 at 6 months to 3.4 months at 24 months. There was also a survival benefit of HSCT in higher risk pts who were transformed to AML during their follow-up which was even higher in terms of gain of months: from 9.89 month if HSCT performed within 6 months to 14.25 months if performed within 18 months. Of note, the loss of survival in lower risk patients who underwent HSCT decreased over time: 11.1 months if HSCT is performed within 6 months and 3.7 months if HSCT is performed within 24 months, probably owing to transition to higher-risk CMML at this stage in some pts, a transition that could not be captured in the present dataset. Conclusion: For the first time, using a multistate model, we could provide evidence that the transplant benefit in CMML is restricted to higher-risk pts, in line with findings in MDS and current guidelines. More analyses will be performed to analyze other subgroups of patients, especially regarding their risk (other classification than CPSS, the role of somatic mutation…). More studies are needed to analyze the role of pre HSCT treatment and its potential impact on post-transplant outcome. Disclosures Robin: Novartis Neovii: Research Funding. Beelen:Medac GmbH Wedel Germany: Consultancy, Honoraria. Fenaux:Celgene Corporation: Honoraria, Research Funding; Astex: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Aprea: Research Funding. Kroeger:Riemser: Research Funding; Novartis: Honoraria, Research Funding; Medac: Honoraria; DKMS: Research Funding; Neovii: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; JAZZ: Honoraria; Sanofi-Aventis: Honoraria. Nazha:Tolero, Karyopharma: Honoraria; MEI: Other: Data monitoring Committee; Novartis: Speakers Bureau; Jazz Pharmacutical: Research Funding; Incyte: Speakers Bureau; Daiichi Sankyo: Consultancy; Abbvie: Consultancy. Rampal:Agios, Apexx, Blueprint Medicines, Celgene, Constellation, and Jazz: Consultancy; Constellation, Incyte, and Stemline Therapeutics: Research Funding. Finke:Riemser: Honoraria, Other: research support, Speakers Bureau; Neovii: Honoraria, Other: research support, Speakers Bureau; Medac: Honoraria, Other: research support, Speakers Bureau. Komrokji:Agios: Consultancy; DSI: Consultancy; pfizer: Consultancy; celgene: Consultancy; JAZZ: Consultancy; Novartis: Speakers Bureau; JAZZ: Speakers Bureau; Incyte: Consultancy. Killick:JAZZ: Honoraria; Celgene: Honoraria; NOVARTIS: Honoraria, Membership on an entity's Board of Directors or advisory committees; ALEXION: Honoraria. Blaise:Molmed: Consultancy, Honoraria; Sanofi: Honoraria; Pierre Fabre medicaments: Honoraria; Jazz Pharmaceuticals: Honoraria. Garcia-Manero:Amphivena: Consultancy, Research Funding; Helsinn: Research Funding; Novartis: Research Funding; AbbVie: Research Funding; Celgene: Consultancy, Research Funding; Astex: Consultancy, Research Funding; Onconova: Research Funding; H3 Biomedicine: Research Funding; Merck: Research Funding. Patnaik:Stem Line Pharmaceuticals.: Membership on an entity's Board of Directors or advisory committees.

Abstract Background: The prognostic significance of cytogenetic abnormalities in chronic myelomonocytic leukemia (CMML) was recently revisited (AJH, 89; 813-818, 2014 and Blood April, 2013). Using a large Mayo Clinic-French Consortium database, we analyzed the molecular and prognostic correlates of cytogenetic abnormalities in CMML. Methods: CMML diagnosis was according to World Health Organization criteria. Cytogenetic analysis and reporting was done according to the International System for Human Cytogenetic Nomenclature. Statistical analyses considered clinical and laboratory parameters obtained at time of cytogenetic studies. Results: Spectrum and frequency of cytogenetic abnormalities: A total of 409 patients participated in this study including, 268 (66%) from the Mayo Clinic and 141 (34%) from the French CMML consortium. Of these, 396 (97%) had ≥20 metaphases and 13 (3%) had ten to 19, analyzed. One hundred and fifteen (30%) patients displayed an abnormal karyotype, including 82 (71%) sole, 20 (17%) two and 13 (11%) complex abnormalities. The most common abnormalities were; +8 (23%), -Y (20%), -7/7q- (14%), 20q- (8%), +21 (8%) and der (3q) (8%). Other cytogenetic abnormalities included 5q-, 12p-, 13q- and i(17q), present at a much lower frequency (0.9-4%). Phenotypic correlates: Abnormal vs normal karyotype was associated with older age (p=0.03), hemoglobin<10 g/dL (p=0.0009), white blood cell count (WBC) >15 x 109/L (p=0.02), absolute neutrophil count (ANC) >10 x 109/L (p=0.03), absolute lymphocyte count (ALC) >2.5 x109/L ( p=0.04), peripheral blood (PB) blast ≥1% (p<0.0001), bone marrow (BM) blast ≥10% (p<0.0001) and circulating immature myeloid cells (IMC) (p=0.0003). +8 (p=0.01), +21 (p=0.03) and der (3q) (p=0.03) were associated with hemoglobin <10 g/dL. -Y was associated with older age (p=0.04), lower PB (p=0.04) and BM (p=0.02) blasts. -7/7q was associated with leukocytosis (p=0.005), neutrophilia (p=0.04), and higher PB blasts (p=0.004). 20q- was associated with thrombocytopenia (p=0.04). Molecular correlates: ASXL1 mutations were associated with abnormal karyotype (p=0.04) and SRSF2 with normal karyotype (p=0.02). In comparison to other abnormal karyotypes, the incidence of ASXL1 mutations was lower in –Y (P=0.04) and der(3q) (p=0.03). U2AF1 mutations were associated with monosomal karyotype (p=0.03) and SF3B1 with der (3q) (p<0.0001). Prognostic relevance : Median follow-up was 1.8 years with 244 (60%) deaths and 79 leukemic transformations (19%). A step-wise survival analysis resulted in three distinct cytogenetic risk categories (Figure 1): high (complex and monosomal karyotype), intermediate (all abnormalities not in high or low risk) and low (normal, sole -Y and sole der (3q)); the corresponding median survivals were 0.2 (HR 8.1, 95% CI 4.6-14.2), 1.7 (HR 1.7, 95% CI 1.2-2.3). In multivariable analysis, the particular cytogenetic risk stratification remained significant in the context of Mayo molecular model (p<0.0001), MDAPS (p<0.0001), and the GFM risk model (P<0.0001). The Mayo-French cytogenetic risk model was also effective in predicting leukemic transformation with HR of 10.9 (95% CI 4.2-27.8) for high and 2.2 (95% CI 1.3-3.7) for intermediate risk groups. Conclusion: Cytogenetic abnormalities are seen in approximately 30% of patients with CMML and display significant associations with certain molecular and phenotypic characteristics. We describe a novel cytogenetic prognostic model for both over-all and leukemia free survival in CMML. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract Introduction: CMML is a clinically heterogeneous myeloid neoplasm hallmarked by the coexistence of dysplastic and proliferative patho-clinical features, which can include cytopenias, constitutional symptoms, splenomegaly, and leukocytosis. However, according to the FAB classification schema, CMML may be differentiated in dysplastic and proliferative subgroups only by the presence of leukocytosis in the latter (WBC ≥13 x 109/L). We hypothesize that incorporation of other clinically discriminating features may yield a more informative CMML stratification system. To address this, we propose three distinct CMML categories and explore their clinical relevance leveraging our existing international CMML database (Padron E et al. Blood Cancer J. 20151). Method: 1622 WHO-defined CMML cases diagnosed between 1973 and 2014 were collected from eight large cancer centres that include up to 80 discrete data elements as previously described1. Cases were placed into three clinically distinct groups and the Pearson Chi-Square test and the Kruskal-Wallis test were applied respectively to compare categorical and continuous characteristics. The Kaplan-Meier (KM) method was used to estimate median OS and the log rank test was used to compare survival curves.Cox models whereapplied to obtain univariate and adjusted hazard ratios. Identification of optimal cut-off values for continuous variable was supported by graphical inspection of martingale residuals from the null Cox model. Statistical analyses were done in SPSS v23 and R v.3.3.0. Results: We propose three categories to delineate clinically distinct CMML subtypes: (1) Myelodysplastic (MD)-CMML: WBC≤10 x 109/L, PB-immature myeloid cells (IMC) = 0%, no splenomegaly (2) MD/MP-CMML: WBC 10-20 x 109/L or WBC ≤10 x 109/L but PB-IMC>0% and/or splenomegaly (3) Myeloproliferative (MP)-CMML: WBC >20 x 109/L. A recursive partitioning approach was used to identify the WBC cut points, with splenomegaly and IMC added to more accurately depict the MPN aspect of CMML. Numbers of patients included in the MD-, MD/MP-, and MP-CMML subcategories were 319 (19.7%), 789 (48.6%) and 514 (31.7%), respectively (Table 1). According to the FAB criteria, the MD/MP group included 521 (66%) MD- (WBC ≤13 x 109/L) and 268 (34%) MP-CMML (WBC>13 x 109/L) patients suggesting that the proposed classification clinically reclassifies FAB-defined CMML. Within the MD/MP group, 344 patients (21.2%) had a WBC <10 x 109/L but with IMC>0% and/or splenomegaly. Comparison of overall survival (OS) among proposed groups demonstrated that this classification schema was capable of discriminating the CMML natural history (Figure 1). In comparison to MD/MP-CMML, the unadjusted OS Hazard Ratio (HR) was 0.60 (95% CI 0.49-0.73) for MD-CMML and 1.57 (95% CI 1.36-1.81) for MP-CMML (p<0.001 for both). This difference was retained after adjusting for BM-Blasts (< vs ≥5%), IPSS or CPSS cytogenetics (High-risk vsInterm/low-risk), and elevated levels of LDH (HR was 0.73 with 95% CI 0.57-0.93, p=0.011 for MD-CMML, and 1.33 with 95% CI 1.12-1.58, p=0.001 for MP-CMML, respectively). We next explored whether each proposed group may have distinct variables that uniquely govern its prognosis. Peripheral blood blasts >5%, RBC- and PLT-transfusion-dependence predicted poor OS only in the MD and MD/MP-subcategories (p<0.005), but had no impact in the MP-CMML. Male gender and elevated LDH were only significantly associated with prognosis in the MD/MP group (p<0.05 and p<0.005, respectively) while absolute lymphocyte count >2.5 x 109/L and absolute monocyte count >10 x109/L were uniquely predictive for shorter survival in the MP-CMML subcategory (p<0.005). Notably, we additionally identified gene mutations that uniquely predicted prognosis in each proposed group (Table 2). Conclusions: We demonstrate that our proposed 3-group clinical classification schema is capable of independently stratifying prognosis. Further, our analysis identified clinical and genetic variables that uniquely govern each group's prognosis, suggesting independent clinical behaviour. Further investigations are warranted to validate these groups. Disclosures Jabbour: ARIAD: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Research Funding; BMS: Consultancy. Fenaux:Celgene, Janssen,Novartis, Astex, Teva: Honoraria, Research Funding. Kantarjian:Bristol-Myers Squibb: Research Funding; ARIAD: Research Funding; Amgen: Research Funding; Pfizer Inc: Research Funding; Delta-Fly Pharma: Research Funding; Novartis: Research Funding. Komrokji:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Speakers Bureau.

Abstract Background Chronic myelomonocytic leukemia (CMML) is a clonal stem cell disorder with overlapping features between myelodysplastic syndromes and myeloproliferative neoplasms. Numerous models exist for CMML prognostication, with more recent studies suggesting (JCO 201; 31:2428) or refuting (Leukemia 2013; 27:1504) the prognostic contribution of ASXL1 mutations. Furthermore, SETBP1 mutations were recently shown to be associated with shortened overall survival (OS) in CMML (Leukemia 2013; 10:1038). In the current international study, we examine these issues in a larger cohort of 431 patients. Methods 431 patients with WHO-defined CMML were included in the study. 235 (55%) were seen at the Mayo Clinic from 1997 through 2012. The remainders were from the French CMML registry (JCO 201; 31:2428). All patients underwent bone marrow (BM) examination and cytogenetic evaluation at diagnosis. DNA analysis for spliceosome component mutations (SRSF2, SF3B1 and U2AF1), ASXL1 and SETBP1 mutations were carried out on BM specimens obtained at diagnosis. In order to address the aforementioned discrepancy regarding the prognostic impact of ASXL1 mutations, relevant analyses in the Mayo cohort were first performed with and without inclusion of missense ASXL1 mutations. ASXL1 mutations from the French cohort did not include missense mutations. We evaluated the prognostic relevance of ASXL1 and SETBPI mutations, as well as several other clinical and laboratory parameters including those previously identified by the MDAPS (Blood 2002;99:840) the Spanish cytogenetic risk stratification (Haematologica 2011;96:375), and the Mayo prognostic model (Leukemia 2013;27;1504). Results Among the 431 study patients, 286 (66%) were males and median age was 73 years (range, 17-93 years). There were 368 (85%) patients with CMML-1 and the remainder had CMML-2. At a median follow-up of 23 months, 260 (60%) deaths and 70 (16%) leukemic transformations were documented. Median survivals were 38 months for CMML-1 and 24 months for CMML-2 (p=0.11). Mutational frequencies were 44% (173/390) for SRSF2, 6% (23/379) for SF3B1, 7% (27/387) for U2AF1, 38% (164/411) for ASXL1 (excluding missense mutations), and 5% (21/431) for SETBP1. Risk stratification was, based on i) Mayo prognostic model: 172 (40%) high, 151 (35%) intermediate and 94 (25 %) low risk, ii) MDAPS: 15 (3%) high, 73 (17%) intermediate-2, 125 (29%) intermediate-1 and 218 (50%) low risk and iii) Spanish cytogenetic stratification system: 316 (73%) low, 43 (10%) intermediate and 50 (12%) high risk. In the Mayo cohort, univariate analysis revealed that the exclusion of missense mutations changed the prognostic impact of ASXL1 mutations from non-significant (p=0.08) to significant (p=0.001). Accordingly, all subsequent analyses excluded missense ASXL1 mutations. In univariate analysis, lower hemoglobin (p<0.0001), lower platelet count (p=0.0027), higher absolute monocyte count (AMC) (p<0.0001), higher absolute lymphocyte count (ALC) (p=0.0002), circulating immature myeloid cells (IMC) (P<0.0001), cytogenetic risk stratification (p<0.0001) and ASXL1 mutations (p<0.0001) were significant for OS. In multivariable analysis, lower hemoglobin (p=0.0001; RR 2, 99% CI 1.6-2.6), lower platelet count (p=0.002; RR 1.5, 99% CI 1.2-1.9), higher AMC (p=0.0002; RR 2.2, 99% CI 1.6-3.1) and ASXL1mutations (p=0.0009; RR 1.9, 99% CI 1.5-2.4) retained their independent negative prognostic impact. Similarly, in univariate analysis, leukemia-free survival (LFS) was negatively affected by age (p=0.0015), lower hemoglobin (p=0.0002), lower platelet count (p=0.0002), higher AMC (p<0.0001), higher ALC (p=0.0001), circulating IMC (p<0.0001), BM blasts (p<0.0001), and cytogenetic risk stratification (p=.0002). ASXL1 (p=0.17) and SETBP1(p=0.87) mutations were not found to be significant. In multivariable analysis, lower platelet count (p=0.0005), higher AMC (P=0.0042), circulating IMC (P=0.008) and cytogenetic risk stratification (p=0.009) retained their independent negative prognostic impact. Conclusions In the current international study of a large cohort of patients with CMML, we confirm and clarify the independent prognostic relevance of ASXL1 mutations. The relatively high frequency of ASXL1 mutations in CMML warrants its inclusion in contemporary prognostic models. Disclosures: No relevant conflicts of interest to declare.