Myeloproliferative Chronic Myelomonocytic Leukemia Research Articles

Influence of Co-Mutational Patterns in Disease Phenotype and Clinical Outcomes of Chronic Myelomonocytic Leukemia

Introduction: Chronic myelomonocytic leukemia (CMML) is characterized by recurrent somatic mutations in a conserved number of genes and functional pathways. Although specific genomic events are associated with disease phenotype and prognosis, identification of genomically-defined disease subgroups based on common recurrent cooperative genomic patterns is needed to refine disease classification and identify disease subsets with unique clinical behavior. Methods: To evaluate if CMML is defined by recurrent co-mutational profiles defining unique clinicopathologic subgroups we evaluated a cohort of 296 patients (pts) with newly diagnosed CMML. Whole bone marrow DNA was subject to 81 gene targeted next-generation sequencing analysis. Akaike information criterion (AIC) method was applied to evaluate mixture model components defining clusters based on mutational profile. Expectation-maximization (EM) algorithm was used for mixture model fitting to multivariate binary data. Unsupervised cluster membership was chosen as a function of the component with the highest weight for any individual, and we examined means of cluster centers. Cox proportional hazards models, regressing overall survival (OS) and leukemia-free survival (LFS), were fit on cluster in some cases and normalized cluster weights in other cases, with and without adjustment for age and sex. Two degree of freedom likelihood ratio tests was performed on cluster and cluster weight in all models regardless of covariate adjustment. Results: Median age of the population was 70 years [range 30-71]; 160 (54%) pts had myeloproliferative CMML (MP-CMML) and 152 (51%) had CMML-2 by WHO classification. Most frequent mutations included TET2 (51%), ASXL1 (48%), SRSF2 (40%), RUNX1 (22%), NRAS (18%), CBL (14%) and KRAS (14%) all present in >10% of pts. Based on frequency and co-occurrence of mutations, AIC optimization identified 3 unique clusters. Clusters based on mutation landscape are shown in Figure 1A. Unsupervised clustering allowed attribution of individual patients to specific clusters. Cluster 1 (C1, n=107), was characterized by near universal presence of ASXL1 mutations (86%), with lower frequency of TET2 mutations, and enrichment of RUNX1 (35%), NRAS (28%) and U2AF1 (18%) mutations. SETBP1 and EZH2 mutations were nearly exclusively observed in C1 (16% and 20% of C1 pts, respectively). All pts with ETV6 mutations belonged to this cluster. Cluster 2 (C2, n=135) was defined by universal presence of TET2 mutations (93%) with frequent SRSF2 co-mutation (56%) and lower frequency of ASXL1 (34%), RUNX1 (15%) or NRAS (12%) mutations. Despite their overall low frequency, BRAF mutations were restricted to C2, while CBL mutations were observed at similar frequencies in C1 and C2. This suggests that co-mutation profiles and genomic context differs among genes involved in RAS pathway signaling. Cluster 3 (C3, n=54) included a minor and more genomically heterogenous group enriched for SF3B1 (25%), KRAS (24%), DNMT3A (22%) and TP53 (15%) mutations, with absence of ASXL1 mutations, and low frequency of TET2 (12%) mutations. All BCORL1 and WT1 mutations and most ASXL2 and CEBPA mutations were in C3. RUNX1 mutations not only were more frequent among C1 but appeared at higher median VAF compared to other clusters (C1: 40%, C2: 11%, C3: 25%, p=0.003). Mutations in U2AF1 had higher median VAF in C3 compared to cluster 1 (49% vs 43%, p=0.017). C1 was enriched for MP-CMML (C1: 64%; C2: 48%; C3: 52%, p<0.001) and had higher frequency of del(7q)/-7 (C1: 11%; C2 0%, C3: 6%, p<0.001) and trisomy 8 (C1: 15%, C2: 7%, C3: 6%, p=0.05). Complex karyotype (C1: 1%, C2: 1%, C3: 22%, p<0.001) was nearly exclusive of C3, while C2 was more likely to be associated with a normal karyotype (C1: 59%; C1: 73%; C3: 41%, p<0.001) and higher median hemoglobin (C1: 9.8g/dL; C2: 12.1g/dL, C3: 9.7g/dL, p<0.001). In total 66% of pts received therapy with hypomethylating agents with no differences in response, median time to or duration of response between clusters. Use of Cox proportional hazards model identified that, when corrected by age and sex, patients on C1 and C3, based on attributed cluster weights, had significantly worse LFS (p=0.02, Figurer 1B) and OS (p=0.05) than those in C2. Conclusions: These data suggest that somatic mutations in CMML have unique patterns of clustering that define disease phenotype and influence disease outcomes.

Results of a Phase II Study of Cladribine, Low Dose Cytarabine and Venetoclax, Alternating with Azacitidine and Venetoclax in Patients with Higher Risk Chronic Myelomonocytic Leukemia or Myelodysplastic Syndromes

INTRODUCTION: Clinical responses to hypomethylating agents (HMAs) in patients (pts) with higher-risk myelodysplastic syndromes (HR-MDS) and myeloproliferative chronic myelomonocytic leukemia (CMML) remain short-lived, with high risk of transformation to acute myeloid leukemia (AML). Prior data suggests use of the purine analogue cladribine can induce monocyte apoptosis and is active in AML, particularly in combination with low dose cytarabine (LDAC) and venetoclax. We aimed to evaluate the safety and activity of cladribine, LDAC and venetoclax in HR-MDS and CMML. METHODS: We designed a phase II basket clinical trial of cladribine combined with LDAC and venetoclax alternating with azacitidine and venetoclax for pts with HR-MDS or CMML. Pts were divided into 4 cohorts: cohort A: MDS with int-1 to high risk by IPSS and >5% blasts with prior HMA-failure (HMA-F); cohort B: CMML-1/CMML-2 with prior HMA-F; cohort C: previously untreated MDS with Int-2 or High risk by IPSS and >10% bone marrow (BM) blasts; cohort D: previously untreated CMML-2 or CMML-1 with at least one high-risk feature (extramedullary disease, splenomegaly of >5cm below costal margin, platelets <100x10 9/L, Hgb level <10g/dL, WBC >13x10 9/L, clonal cytogenetic abnormality [other than monosomy Y]). HMA-F was defined as no response after 6 cycles of therapy with HMA or relapse/progression after any number of cycles. Induction consisted of cladribine 5mg/m 2 daily IV on days 1-3, cytarabine 20mg s.c bid days 1-5 and venetoclax 400mg daily days 1-5. Re-induction was allowed in pts not achieving response after induction. Consolidations consisted of azacitidine 75mg/m 2 daily days 1-7 with venetoclax 400mg daily days 1-7 alternating with cladribine 5mg/m 2 days 1-3, cytarabine 20mg s.c bid days 1-5 and venetoclax 400mg days 1-5 every two 28-day cycles. The primary end point was to evaluate safety, efficacy, and tolerability of the combination. Responses were evaluated following 2006 IWG criteria. The Kaplan-Meir product-limit method was used to estimate median survival. RESULTS: Between October 2022 and June 2023, 20 pts have been treated: 10, 5, 3 and 2 in cohorts A, B, C and D, respectively. Thirteen pts had MDS, and 7 had CMML. Median age was 74 years (range 52-83). Among MDS pts, 8 (62%) had int-2 and 5 (38%) had high risk by IPSS. By the Molecular IPSS, 10 (79%) had very high, 1 (8%) had high, 1 (8%) had moderate high and 1 (8%) had low risk. Among CMML pts, 4 (57%) had high, 2 (29%) had intermediate-2 and 1 (14%) had intermediate-1 risk by the CPSS Molecular score. Among HMA-F cohorts, median number of prior therapies was 1 (range 1-4), median cycles of prior HMA was 6 (range 2-63) and 4 (27%) pts had failure to prior venetoclax therapy. Most common adverse events (AEs) were hypoalbuminemia (40%), nausea (40%), sinus bradycardia (40%), alanine aminotransferase increase (35%), constipation (35%), lower extremity edema (35%), fatigue (35%) and hypocalcemia (35%) Most common grade 3-4 AEs were leukopenia (20%) and febrile neutropenia (15%). The 4-week and 8-week cumulative incidences of mortality were 0%. Median number of cycles was 2 (range 1-6). Median cycles to best response was 1 (range 1-3). Among HMA naïve pts (cohorts C and D), the ORR was 80% (n=4): CR in 2 (40%), mCR in 2 (40%). Based on 2023 IWG response criteria, responses in cohort C (n=3) included: CR in 2 (67%) and CR bilineage (CRbi) in 1 (33%). Based on 2015 IWG MDS/MPN criteria, responses in cohort D (n=2) included optimal marrow response and clinical benefit in 1 (50%) and 1 (50%) pts, respectively. Among HMA-F pts (cohorts A and B) the ORR was 20%: 1 CR (10%) and 1 (10%) mCR with HI. Median follow up is 5.3 months (95% CI 2.4-81). Median EFS is 2.1 months in cohorts A and B and not reached in C and D (Fig 1A). Median OS has not been reached for all cohorts (Fig 1B). At the time of data cut-off, all pts in cohorts C and D discontinued study to proceed with hematopoietic stem-cell transplantation (HSCT). Among cohorts A and B, 2 pts (13%) discontinued study to proceed with HSCT, 5 (33%) due to transformation to AML, 2 (13%) due to no response, 2 (13%) due to physician choice, 1 (7%) due to patient choice and 2 (13%) pts remain on study. CONCLUSIONS: Preliminary data suggests the use of cladribine, LDAC and venetoclax can be safely administered in pts with very high risk MDS and CMML with early promising results in pts with de novo disease.

Molecular features of 109 patients with chronic myelomonocytic leukemia in a single center

Objective: To explore the molecular features of chronic myelomonocytic leukemia (CMML) . Methods: According to 2022 World Health Organization (WHO 2022) classification, 113 CMML patients and 840 myelodysplastic syndrome (MDS) patients from March 2016 to October 2021 were reclassified, and the clinical and molecular features of CMML patients were analyzed. Results: Among 113 CMML patients, 23 (20.4%) were re-diagnosed as acute myeloid leukemia (AML), including 18 AML with NPM1 mutation, 3 AML with KMT2A rearrangement, and 2 AML with MECOM rearrangement. The remaining 90 patients met the WHO 2022 CMML criteria. In addition, 19 of 840 (2.3%) MDS patients met the WHO 2022 CMML criteria. At least one gene mutation was detected in 99% of CMML patients, and the median number of mutations was 4. The genes with mutation frequency ≥ 10% were: ASXL1 (48%), NRAS (34%), RUNX1 (33%), TET2 (28%), U2AF1 (23%), SRSF2 (21.1%), SETBP1 (20%), KRAS (17%), CBL (15.6%) and DNMT3A (11%). Paired analysis showed that SRSF2 was frequently co-mutated with ASXL1 (OR=4.129, 95% CI 1.481-11.510, Q=0.007) and TET2 (OR=5.276, 95% CI 1.979-14.065, Q=0.001). SRSF2 and TET2 frequently occurred in elderly (≥60 years) patients with myeloproliferative CMML (MP-CMML). U2AF1 mutations were often mutually exclusive with TET2 (OR=0.174, 95% CI 0.038-0.791, Q=0.024), and were common in younger (<60 years) patients with myelodysplastic CMML (MD-CMML). Compared with patients with absolute monocyte count (AMoC) ≥1×10(9)/L and <1×10(9)/L, the former had a higher median age of onset (60 years old vs 47 years old, P<0.001), white blood cell count (15.9×10(9)/L vs 4.4×10(9)/L, P<0.001), proportion of monocytes (21.5% vs 15%, P=0.001), and hemoglobin level (86 g/L vs 74 g/L, P=0.014). TET2 mutations (P=0.021) and SRSF2 mutations (P=0.011) were more common in patients with AMoC≥1×10(9)/L, whereas U2AF1 mutations (P<0.001) were more common in patients with AMoC<1×10(9)/L. There was no significant difference in the frequency of other gene mutations between the two groups. Conclusion: According to WHO 2022 classification, nearly 20% of CMML patients had AMoC<1×10(9)/L at the time of diagnosis, and MD-CMML and MP-CMML had different molecular features.

Clinical Characteristics and Survival Analysis of Patients with Chronic Myelomonocytic Leukemia

To investigate the clinical characteristics, prognostic factors and efficacy of hypomethylating agent (HMA) in patients with chronic myelomonocytic leukemia (CMML). The clinical data of 37 newly diagnosed patients with CMML was analyzed retrospectively, and their clinical characteristics and the efficacy of HMA were summarized. Kaplan-Meier and Log-rank test were used for univariate survival analysis, and Cox proportional hazards regression model was used for multivariate analysis. The median age at diagnosis was 67 years old. Their common manifestations included fatigue, bleeding, abnormal blood routine and fever. Most patients had splenomegaly. According to FAB classification, there were 6 cases of myelodysplastic CMML and 31 cases of myeloproliferative CMML, while according to WHO classification, 8 patients belonged to CMML-0, 9 patients to CMML-1 and 20 patients to CMML-2. At the time of diagnosis, the median white blood cell count was 32.84×109/L, median hemoglobin (Hb) was 101 g/L, median platelet count was 65×109/L, median absolute monocyte count was 9.53×109//L, median absolute neutrophil count (ANC) was 11.29×109//L and median lactate dehydrogenase (LDH) was 374 U/L. Cytogenetic abnormalities were found in 4 cases among the 31 patients who underwent karyotype analysis or fluorescence in situ hybridization detection. There were 12 patients who had analyzable results and gene mutations were identified in 11 cases, including ASXL1, NRAS, TET2, SRSF2 and RUNX1. Among the 6 patients who were treated with HMA and could be evaluated for efficacy, 2 patients achieved complete remission, 1 patient achieved partial remission and 2 patients achieved clinical benefit. Compared with the non-HMA treatment group, overall survival (OS) time was not significantly prolonged in the HMA treatment group. Univariate analysis showed that Hb<100 g/L, ANC≥12×109/L, LDH≥250 U/L and peripheral blood (PB) blasts ≥5% were significantly associated with poor OS, while WHO classification CMML-2, Hb<100 g/L, ANC≥12×109/L, LDH≥250 U/L and PB blasts≥5% were significantly associated with poor leukemia-free survival (LFS) (P<0.05). Multivariate analysis showed that ANC≥12×109/L and PB blasts≥5% were significantly associated with poor OS and LFS (P<0.05). CMML has high heterogeneity in clinical characteristics, genetic changes, prognosis and treatment response. HMA can not significantly improve the survival of CMML patients. ANC≥12×109/L and PB blasts≥5% are independent prognostic factors of OS and LFS in patients with CMML.

Trial in Progress: A Phase I/II Study to Assess Safety, Tolerability and Preliminary Efficacy of Bexmarilimab in Combination with Standard of Care in Patients with Hematological Malignancies (BEXMAB)

Background: Emerging data on the role of leukemic cells on shaping the tumor immune environment places macrophages as target cells and immune checkpoints in acute myeloid leukemia (AML) (Miari et. al. Front. Cell Dev. Biol.2021; Sallman et. al. Blood 2019). CLEVER-1 (common lymphatic endothelial and vascular endothelial receptor-1) constitutes such macrophage checkpoint. The receptor contributes to tumor immune tolerance by antigen clearing and T cell inhibition. In multiple models, tumor growth is significantly reduced in CLEVER-1 absence (Viitala et. al. Clin Cancer Res 2019). CLEVER-1 expression level is a prognostic factor for poor outcomes in AML (Pölönen et. al. Cancer Research 2019) and its suppression inhibits leukemia cell growth. Analyses suggests lower expression is associated with venetoclax sensitivity (Lin et al. Mol Ther 2019). Bexmarilimab (FP-1305; BEX), an IgG4 monoclonal antibody, binds CLEVER-1 and alters the function of macrophages and inactive T cells. BEX was shown to increase antigen presentation, induce proinflammatory cytokines and infiltration of activated T cells (Viitala et. al. Clin Cancer Res 2019). The therapeutic potential of BEX is supported with data from the MATINS study (NCT03733990) evaluating single agent in advanced solid tumors. Up to 40% of patients in selected indications experience disease control (stable disease/partial response) associated with a 65% chance of 1-year overall survival (OS) compared to 11% of patients without disease control. BEX treatment is well tolerated without any dose limiting toxicity (DLT) reported. CLEVER-1 is highly expression on malignant blasts and monocytes of bone marrow from AML and myelodysplastic syndrome (MDS) patients. Treatment of these BM cells with BEX alone or in combination with azacitidine or venetoclax results in enhanced antigen presentation capacity and increased activation markers on effector T cells with synergistic effects (EHA 2022 P380). Study Design and Methods: The PhI/II study investigates BEX treatment plus standard of care in MDS, chronic myelomonocytic leukemia (CMML) frontline or hypomethylating agent (HMA)-failed patients or newly diagnosed AML or relapsed/refractory (r/r) AML patients (NCT05428969). Enrollment is ongoing. Ph I is a dose escalation using a Bayesian optimal interval (BOIN) design to explore 4 dose levels of BEX in a cohort size of 5 with 1.0 mg/kg as starting dose. BEX plus azacitidine (doublet) is assessed in a mixed cohort of MDS, CMML frontline and hypomethylating agent (HMA)-failure patients or r/r AML patients. Dose determination may then be performed in separate indications. BEX plus azacitidine + venetocolax (triplet) will follow a similar BOIN design for dose determination in patients with newly diagnosed AML unfit for induction chemotherapy. BEX is dosed in 28-day cycles Q1W during cycles 1-3 followed by Q2W dosing, until disease progression or intolerable toxicity. Standard of care therapy is administered as per label. During Ph II, selected indications are explored for efficacy when BEX is administered at recommended phase 2 dose (RP2D) determined in the doublet and triplet. Dose expansion follows a 2-Stage design with indication-specific target efficacy rates, including complete remission +/- incomplete hematologic recovery, overall response rate or minimal residual disease (MRD)-negativity. Primary endpoints are safety and tolerability, RP2D of BEX and preliminary efficacy. Secondary endpoints include extended efficacy for duration of response, event free survival and OS. Exploratory endpoints are focused on pharmacodynamic parameters for immunological and cellular read-outs and the association of predictive biomarker of BEX clinical activity in different patient sub-groups. Key eligibility includes patient ≥ 18 years of age presenting with morphologically confirmed diagnosis of either MDS (intermediate-very high rIPSS risk), CMML-2 with indication for azacitidine treatment; CMML and MDS patients with failure to HMA therapy, confirmed diagnosis of r/r AML following at least 1 prior treatment line or diagnosis of AML in patients unfit for induction therapy with indication for azacitidine + venetoclax. Patients with APL or myeloproliferative CMML, active auto-immune disorder or requiring systemic corticosteroid or other immunosuppressive treatment are excluded. Approximately 181 patients at 10 US and EU sites will be enrolled.

Response to azacitidine in patients with chronic myelomonocytic leukemia according to overlap myelodysplastic/myeloproliferative neoplasms criteria

BackgroundAzacitidine (AZA) is approved for the treatment of high-risk chronic myelomonocytic leukemia (CMML) of myelodysplastic (MD) subtype. Data of response rates using the specific response criteria for this disease are scarce. The aim of this study was to evaluate the response to AZA in patients diagnosed with CMML from the Spanish Registry of Myelodysplastic Syndromes (MDS) applying the overlap myelodysplastic/myeloproliferative neoplasms (MDS/MPN) response criteria. MethodsWe retrospectively studied 91 patients with CMML treated with at least one cycle of AZA from the Spanish Registry of MDS. As it was a real-world study, the response rate was evaluated between cycle 4 and 6, applying the MDS/MPN response criteria FindingsThe overall response rate at cycle 4–6 was 58%. Almost half of the patients achieved transfusion independence and one quarter showed clinical benefit, regardless of the CMML French-American-British (FAB) and World Health Organization (WHO) subtypes and CMML Specific Prognosis Scoring (CPSS) risk groups. Toxicity was higher in the MD-CMML subtype. InterpretationIn our series, most CMML patients achieved an overall response rate with AZA according to the overlap-MDS/MPN response criteria regardless of the CMML FAB and WHO subtypes and CPSS risk groups. Thus, AZA may also be a treatment option for patients with the myeloproliferative CMML subtype and those with a lower-risk CPSS, but symptomatic.

Outcomes of Patients with Chronic Myelomonocytic Leukemia (CMML) Treated with Hypomethylating Agents

Outcomes of Patients with Chronic Myelomonocytic Leukemia (CMML) Treated with Hypomethylating Agents

Transcriptomic Features and Deregulation of Genes Involved in Monopoiesis Influence Outcomes of Patients with Chronic Myelomonocytic Leukemia

INTRODUCTION: Chronic myelomonocytic leukemia (CMML) is characterized by TET2, SRSF2, ASXL1 and RAS pathway mutations known to induce myelomonocytic bias. We have previously shown that upregulation of KDM6B, a histone demethylase that acts as an innate immune signal activator, leads to myeloid bias and expansion of immature myelomonocytic precursors and LSK cells in mice, resulting in rapid development of a myeloproliferative CMML (MP-CMML) phenotype particularly in cooperation with TET2 deletion. However, the role of genes involved in innate immunity regulation and monocyte differentiation in CMML phenotype and outcomes remains unclear. METHODS: We evaluated bone marrow aspirates from 19 patients with CMML and compared their transcriptomic features to those of healthy individuals obtained from AllCells (Emeryville, CA). CD34+ cells were isolated using the CD34 MicroBead Kit and RNA was isolated using the PicoPure RNA isolation kit. Fastq files were mapped to the human genome (build GRCh38) in TopHat2 using the default options. Differential gene expression analysis was conducted using DESeq2 in R version 3.4.2. Pathway enrichment analysis was performed using gene set enrichment analysis, with the fgsea library in R. Genes were ranked according to their Spearman correlation with the gene of interest, and this ranking was used as the input to fgsea. 10 000 gene permutations were used to calculate statistical significance, and a false discovery corrected p-value of 0.05 was required for statistical significance of a gene set. Cox regression and time ROC curves were used to study the relationship between gene expression and survival. We implemented Kaplan-Meier estimator along with optimum cutoff method to show the survival behavior in high versus low predicted model groups. RESULTS: Compared to healthy controls, a total of 1495 genes had significantly differential expression in CMML (q&amp;lt;0.05, FC&amp;gt;2) including 1271 genes which were significantly upregulated, and 224 which were significantly downregulated in CMML (Figure 1A). Gene set enrichment analysis identified 162 gene sets with differential expression in CMML compared to control (q&amp;lt;0.05). Top upregulated genes were associated with interferon (IFN) alpha and beta signaling, chemokine receptors, IFN-gamma, GPC receptor ligand signaling and genes involved in immunomodulatory interactions between lymphoid and non-lymphoid cells (Figure 1B). Unsupervised clustering of gene expression profiles did not discriminate MP-CMML from myelodysplastic (MD-CMML). However, 20 genes were significantly overexpressed and 16 were significantly downregulated in patients with MP-CMML compared to MD-CMML (q&amp;lt;0.05, FC&amp;gt;2). In addition, 6 gene sets were differentially upregulated and 139 were significantly downregulated in pts with MP-CMML compared to MD-CMML (Figure 1C). To evaluate aberrant monopoiesis in CMML, we compared the expression of genes reported to be involved in regulation of monopoiesis among healthy controls and patients with CMML. A total of 23 genes involved in regulation of monopoiesis were found to be upregulated in CMML (Figure 1D). No significant differences in expression of these genes was found between MP-CMML and MD-CMML. To determine if aberrant expression of genes involved in monopoiesis influenced outcomes of pts with CMML, we developed a prediction model using Cox regression including 18 of these genes. Use of this model with optimum cutoffs allowed segregation of pts into two prognostic subsets with distinct survival outcomes (Figure 1E). Use of ROC curves identified high AUC particularly in pts with prolonged survival (&amp;gt;40 months). CONCLUSIONS: CMML is characterized by upregulation of IFN and chemokine receptor signaling which could represent potential therapeutic targets. Aberrant expression of genes involved in regulation of monopoiesis may influence prognosis in CMML. Figure Disclosures Sasaki: Otsuka: Honoraria; Pfizer Japan: Consultancy; Daiichi Sankyo: Consultancy; Novartis: Consultancy, Research Funding. Kantarjian:Sanofi: Research Funding; Pfizer: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; BMS: Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Immunogen: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Ascentage: Research Funding; Adaptive biotechnologies: Honoraria; Aptitute Health: Honoraria; BioAscend: Honoraria; Delta Fly: Honoraria; Janssen: Honoraria; Oxford Biomedical: Honoraria; Jazz: Research Funding. Garcia-Manero:AbbVie: Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Onconova: Research Funding; Acceleron Pharmaceuticals: Consultancy, Honoraria; H3 Biomedicine: Research Funding; Jazz Pharmaceuticals: Consultancy; Merck: Research Funding; Amphivena Therapeutics: Research Funding; Helsinn Therapeutics: Consultancy, Honoraria, Research Funding; Astex Pharmaceuticals: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding.

Results of a Phase 2 Trial of the Monocyte-Targeted Histone Deacetylase Inhibitor Tefinostat (CHR-2845) in Chronic Myelomonocytic Leukemia (CMML) — the UK Monocle Study

BackgroundChronic myelomonocytic leukemia (CMML) is a highly heterogeneous myeloid neoplasm with poor prognosis and limited therapeutic options. Tefinostat (CHR-2845) is a cell permeant ester that is converted to an active acid histone deacetylase (HDAC) inhibitor (CHR-2847) by human carboxylesterase 1 (hCE-1), an enzyme predominantly found in cells of monocyte lineage. Pre-clinical studies confirmed selective activity of tefinostat, correlating with hCE-1 expression and acetylation induction, in monocyte derived cell lines, primary CMML and AML (M4/M5) cells (1). A phase 1 study in refractory haematological malignancies showed tefinostat to be well tolerated, with complete remission reported in 1/2 CMML patients (2). Given the compelling rationale for selective activity in monocytoid malignancies, we conducted a phase 2 study to assess safety and efficacy of tefinostat in CMML.MethodsMONOCLE was a single arm phase 2 trial conducted to a Bryant and Day 2-stage design with dual primary endpoints of safety and clinical efficacy. CMML-2 patients were included; additionally CMML-1 patients with symptomatic bone marrow failure or proliferative disease, symptomatic splenomegaly, extramedullary involvement, systemic symptoms or CMML-specific Prognostic Score (CPSS) int-2/high. Tefinostat was administered orally in continuous 28-day cycles starting at 360mg once daily, increasing to 480mg after 4 weeks if well tolerated. Concomitant hydroxycarbamide was permitted only with cycles 1-3. Clinical response was assessed according to International Consortium MDS/MPN Response Criteria (3); responding patients at cycle 6 were permitted to continue therapy. Toxicity was assessed according to CTCAE v4.0.ResultsIn stage 1, 21 patients were enrolled at 9 centers (Jan-Sep 2017). 20 patients received tefinostat (median age 75 years [64-88], M/F 14/6) including 16 with CMML-1 (80%) and 4 CMML-2 (20%), 8 (40%) with myelodysplastic and 12 (60%) myeloproliferative CMML; respective proportions in CPSS low/int-1/int-2/high risk groups were 5/50/40/5%. Myeloid NGS analysis confirmed a molecularly relatively high risk population: 70% ASXL1 mutation frequency and median 4 (2-7) mutations per patient; other most commonly observed mutations being TET2 (65%), SRSF2 (50%), EZH2 (35%) and NRAS (35%). Prior therapy included azacitidine (3 patients) and hydroxycarbamide (7). 17/20 patients had high hCE-1 levels, assessed flow cytometrically at trial entry in monocytoid cells (vs bulk myeloid population). Median number of cycles of tefinostat received was 4 (1-15). Of 13 patients completing ≥3 cycles of tefinostat, 1 patient achieved clinical benefit (partial bone marrow response at cycle 6 with red cell transfusion independence sustained over 15 cycles of treatment), 9 had stable disease (of whom 1 had transient clinical benefit [MPN-SAF symptom reduction] which was not sustained to cycle 6) and 3 had progressive disease. Most frequent non-hematologic adverse events of any grade were raised creatinine (55% patients), fatigue (40%) and nausea/vomiting (30%). Grade ≥3 AEs judged potentially related to tefinostat included thrombocytopenia (3 patients), fatigue (2), raised creatinine (2), anorexia, AV block, nausea and neutropenia (1 each). Creatinine rises were in all cases reversible following tefinostat dose reduction/cessation. Induction of intracellular lysine acetylation in monocytes (a marker of HDAC inhibition) was observed in 50% of patients (including clinical responders), peaking between days 15-28 of cycle 1. While no clear relationship between baseline hCE-1 expression and clinical response was evident, reductions in marrow monocyte and myeloid blast fractions were seen in both clinical responders.ConclusionFollowing failure to achieve a pre-defined minimum number of clinical responses to tefinostat, patient recruitment was not continued into stage 2 of this phase 2 study. Drug tolerability was encouraging although observed renal effects will likely preclude dose escalation in this challenging, often frail patient group. Despite compelling scientific rationale and pre-clinical data favoring this monocyte targeted treatment approach we were unable to demonstrate a clinically significant single agent disease modifying effect in CMML.(1) Zabkiewicz J. Oncotarget 2016; 7: 16650-62(2) Ossenkoppele G. Br J Haem 2013; 162: 191-201(3) Savona M. Blood 2015; 125: 1857-65 DisclosuresKnapper:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Other: Meeting and travel support; Jazz: Other: Meeting and travel support; Daiichi Sankyo: Other: Meeting and travel support; Chroma Therapeutics: Research Funding. Hills:Daiichi Sankyo: Consultancy, Honoraria. Dillon:Teva Pharmaceuticals UK: Consultancy, Honoraria; AbbVie UK: Consultancy, Honoraria. Pocock:Kent & Canterbury Hospital: Employment. Culligan:Pfizer: Honoraria; Takeda: Honoraria, Other: Support to attend conferences; JAZZ: Honoraria; Merck Sharp & Dohme (MSD): Honoraria; Abbvie: Other: Support to attend conferences; Celgene: Other: Support to attend conferences; Daiichi-Sankyo: Other: Support to attend conferences.

Impact of SNP array karyotyping on the diagnosis and the outcome of chronic myelomonocytic leukemia with low risk cytogenetic features or no metaphases.

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic disorder with heterogeneous clinical, morphological and genetic characteristics. Clonal cytogenetic abnormalities are found in 20-30% of patients with CMML. Patients with low risk cytogenetic features (normal karyotype and isolated loss of Y chromosome) account for ∼80% of CMML patients and often fall into the low risk categories of CMML prognostic scores. We hypothesized that single nucleotide polymorphism arrays (SNP-A) karyotyping could detect cryptic chromosomal alterations with prognostic impact in these subgroup of patients. SNP-A were performed at diagnosis in 128 CMML patients with low risk karyotypes or uninformative results for conventional G-banding cytogenetics (CC). Copy number alterations (CNAs) and regions of copy number neutral loss of heterozygosity (CNN-LOH) were detected in 67% of patients. Recurrent CNAs included gains in regions 8p12 and 21q22 as well as losses in 10q21.1 and 12p13.2. Interstitial CNN-LOHs were recurrently detected in the following regions: 4q24-4q35, 7q32.1-7q36.3, and 11q13.3-11q25. Statistical analysis showed that some of the alterations detected by SNP-A associated with the patients' outcome. A shortened overall survival (OS) and progression free survival (PFS) was observed in cases where the affected size of the genome (considering CNAs and CNN-LOHs) was >11 Mb. In addition, presence of interstitial CNN-LOH was predictive of poor OS. Presence of CNAs (≥1) associated with poorer OS and PFS in the patients with myeloproliferative CMML. Overall, SNP-A analysis increased the diagnostic yield in patients with low risk cytogenetic features or uninformative CC and added prognostic value to this subset of patients.

RAS Mutations Contribute to Evolution of Chronic Myelomonocytic Leukemia to the Proliferative Variant

The biological and clinical heterogeneity of chronic myelomonocytic leukemia features renders its classification difficult. Moreover, because of the limited knowledge of the mechanisms involved in malignant evolution, chronic myelomonocytic leukemia remains a diagnostic and therapeutic challenge and a poor prognosis disease. We aimed to verify the biological and clinical significance of the discrimination, based on the leukocyte count, between myelodysplastic chronic myelomonocytic leukemia (MD-CMML) and myeloproliferative chronic myelomonocytic leukemia (MP-CMML). Peripheral blood samples from 22 patients classified as MD-CMML and 18 as MP-CMML were collected at different time points during disease course, and patients' clinical characteristics were examined. RAS mutational screening was done by sequencing and, for each substitution identified, a highly selective allele-specific PCR was set up to screen all specimens. MP-CMML patients showed a significantly poorer survival (P = 0.003) and a higher frequency of RAS mutations (P = 0.033) by sequencing compared with MD-CMML. Overall, five MD-CMML patients progressed to myeloproliferative disease: in two, allele-specific PCR unveiled low levels of the RAS mutations predominating in the myeloproliferative phase at the time of myelodysplastic disease, documenting for the first time the expansion of a RAS mutated clone in concomitance with chronic myelomonocytic leukemia evolution. Moreover, one of the progressed patients harbored the FLT3-ITD and two MP-CMML patients presented with the JAK2 V617F substitution. All these lesions were mutually exclusive. Our results strongly suggest RAS mutations to function as a secondary event that contributes to development of the chronic myelomonocytic leukemia variant with the poorer prognosis (MP-CMML) and therefore advise their detection to be implemented in chronic myelomonocytic leukemia diagnostics and monitoring.