Chronic myelomonocytic leukemia: 2013 update on diagnosis, risk stratification, and management

Disulfiram/cytarabine eradicates a subset of acute myeloid leukemia stem cells with high aldehyde dehydrogenase expression

Most patients with acute myeloid leukemia (AML) achieve complete remission (CR) after induction chemotherapy, however, in some patients, the disease subsequently relapses and may lead to death. Leukemia stem cells (LSC) have been identified as the main cause for recurrence. Increased aldehyde dehydrogenase (ALDHhigh) activity in a variety of cancer stem cells prevents effective action of chemotherapeutic drugs. In this study, we found that approximately 50.7% of AML patients had ALDHhigh, and the presence of ALDHhigh stem cells was associated with poor cytogenetic prognosis. Lentiviral vector transduced ALDHhigh leukemia cell lines are insensitive to the conventional chemotherapy drug cytarabine, and inhibition of ALDH activity by disulfiram (DSF) can increase the sensitivity of ALDHhigh leukemia cells to cytarabine. Unlike traditional chemotherapy drugs, DSF is not toxic to healthy umbilical cord blood stem cells. An ALDHhigh leukemia cell xenograft model was established using immunodeficient mice to mimic the disease environment, and DSF and cytarabine were found to eliminate the ALDHhigh leukemia cells in transplanted mice while not affecting the healthy blood cells of mice. These findings suggest that DSF may have therapeutic potential by inhibiting ALDH activity and thereby increasing chemosensitivity.

The targeted histone deacetylase inhibitor tefinostat (CHR-2845) shows selective in vitro efficacy in monocytoid-lineage leukaemias

Tefinostat (CHR-2845) is a novel monocyte/macrophage-targeted histone deacetylase (HDAC) inhibitor which is cleaved into its active acid by the intracellular esterase human carboxylesterase-1 (hCE-1). The in vitro efficacy of tefinostat was characterised in cell lines and in a cohort of 73 primary AML and CMML samples. Dose-dependent induction of apoptosis and significant growth inhibitory effects were seen in myelomonocytic (M4), monocytic/monoblastic (M5) and CMML samples in comparison to non-monocytoid AML sub-types (p = 0.007). Importantly, no growth inhibitory effects were seen in normal bone marrow CD34⁺ cells exposed to AML-toxic doses of tefinostat in clonogenic assays. Expression of hCE-1 was measured by intracellular flow cytometry and immunoblotting across the cohort, with highest levels seen in M5 AML patients. hCE-1 levels correlated with significantly increased tefinostat sensitivity (low EC50) as measured by growth inhibition assays (p = 0.001) and concomitant elevation of the mature monocytoid marker CD14⁺. Strong induction of intracellular histone protein acetylation was observed in tefinostat-responsive samples, as were high levels of the DNA damage sensor γ-H2A.X, highlighting potential biomarkers of patient responsiveness. Synergistic interaction between tefinostat and the current standard treatment cytarabine was demonstrated in dose response and clonogenic assays using simultaneous drug addition in primary samples (median Combination Index value = 0.51). These data provide a strong rationale for the further clinical evaluation of tefinostat in monocytoid-lineage haematological neoplasms including CMML and monocyte-lineage AMLs.

A phase II, multicentre trial of decitabine in higher-risk chronic myelomonocytic leukemia

Chronic myelomonocytic leukemia (CMML) is a complex clonal hematological disorder classified among myelodysplastic (MDS)/myeloproliferative neoplasms. Prognosis is poor and there is a lack of effective treatments. The hypomethylating agent decitabine has shown activity against MDS and elderly acute myeloid leukemia, but there is little data focusing specifically on its efficacy in CMML. In this prospective, phase 2 Italian study, CMML patients received intravenous decitabine 20 mg/m² per day on Days 1–5 of a 28-day treatment cycle. Response was evaluated after four and six cycles; patients responding at the end of six cycles could continue treatment with decitabine. Forty-three patients were enrolled; >50% were high-risk according to four CMML-specific scoring systems. In the intent-to-treat population (n=42), the overall response rate after six cycles was 47.6%, with seven complete responses (16.6%), eight marrow responses (19%), one partial response (2.4%) and four hematological improvements (9.5%). After a median follow-up of 51.5 months (range: 44.4–57.2), median overall survival was 17 months, with responders having a significantly longer survival than non-responders (P=0.02). Grade 3/4 anemia, neutropenia and thrombocytopenia occurred in 28.6%, 50% and 38% of patients, respectively. Decitabine appears to be an effective and well-tolerated treatment for patients with high-risk CMML.

ASXL1 plays an important role in erythropoiesis

ASXL1 mutations are found in a spectrum of myeloid malignancies with poor prognosis. Recently, we reported that Asxl1^+/− mice develop myelodysplastic syndrome (MDS) or MDS and myeloproliferative neoplasms (MPN) overlapping diseases (MDS/MPN). Although defective erythroid maturation and anemia are associated with the prognosis of patients with MDS or MDS/MPN, the role of ASXL1 in erythropoiesis remains unclear. Here, we showed that chronic myelomonocytic leukemia (CMML) patients with ASXL1 mutations exhibited more severe anemia with a significantly increased proportion of bone marrow (BM) early stage erythroblasts and reduced enucleated erythrocytes compared to CMML patients with WT ASXL1. Knockdown of ASXL1 in cord blood CD34⁺ cells reduced erythropoiesis and impaired erythrocyte enucleation. Consistently, the BM and spleens of VavCre⁺;Asxl1^f/f (Asxl1^∆/∆) mice had less numbers of erythroid progenitors than Asxl1^f/f controls. Asxl1^∆/∆ mice also had an increased percentage of erythroblasts and a reduced erythrocyte enucleation in their BM compared to littermate controls. Furthermore, Asxl1^∆/∆ erythroblasts revealed altered expression of genes involved in erythroid development and homeostasis, which was associated with lower levels of H3K27me3 and H3K4me3. Our study unveils a key role for ASXL1 in erythropoiesis and indicates that ASXL1 loss hinders erythroid development/maturation, which could be of prognostic value for MDS/MPN patients.

An unexpected complication of chronic myelomonocytic leukemia: severe renal failure due to malignant tubulo-interstitial cell infiltration

Acute renal failure may complicate the course of a hematologic malignancy but is a highly unusual finding in patients with chronic myelomonocytic leukemia. Kidney biopsy is rarely performed in this setting, and the pathologic substrate underlying kidney injury is not well identified. We present a case of a biopsy-proven acute tubulo-interstitial nephritis due to massive infiltration of neoplastic myelomonocytic cells. Since the leukemic process involving the kidney may respond favorably to treatment, a renal biopsy should be considered in any patient presenting with unexplained severe or evolving kidney disease.

Prognostic impact of acquisition of cytogenetic abnormalities during the course of chronic myelomonocytic leukemia

Karyotypic abnormalities are detected in 20-40% of chronic myelomonocytic leukemia (CMML) patients at initial diagnosis and have been shown to correlate with patients' outcome. The significance of acquisition of cytogenetic abnormalities (ACA) during the course of CMML, however, is largely unknown. In a cohort of 314 CMML patients, karyotypic abnormalities were detected in 106 (34%) patients at the time of diagnosis; and ACA were detected in 80 (25%) patients after a median interval of 17 months (range, 2-117 months). The most frequently observed ACA were a complex karyotype, followed by +21, -7/del(7q), del(20q), i(17q), and -17/del(17p). ACA appeared to occur more frequently in patients with a normal or lower risk karyotype. Progression to AML was seen in 44 of 80 (55%) patients with ACA versus 67 of 234 (29%) patients without ACA (P < 0.0001). Presence of ACA predicted an inferior leukemia-free survival (LFS) by univariate (P = 0.0435) and multivariate analysis (HR = 1.892, P = 0.006). While acquisition of a complex karyotype was positively correlated with AML progression (P = 0.0086), del(20q) was associated with a stable disease (P = 0.0198). We conclude that ACA occur in ∼20-30% of CMML patients during the course of disease, and are significantly associated with AML progression and a shorter LFS. Karyotypic abnormalities, either present at diagnosis or acquired during the course of disease, have prognostic implication in CMML patients.

Prognostic Value of Anemia and C-Reactive Protein Levels in Diffuse Large B-Cell Lymphoma

PURPOSE

To determine the prognostic value of pretreatment anemia, pretreatment elevated C-reactive protein (CRP) levels, and 6-month posttreatment anemia in patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL) treated with rituximab, cyclophosphamide, hydroxydaunorubicin, Oncovin, and prednisolone (R-CHOP).

PATIENTS AND METHODS

A total of 104 patients with newly diagnosed DLBCL were retrospectively included. Pretreatment hemoglobin and CRP levels and 6-month posttreatment hemoglobin levels were measured. Cox regression analyses were used to determine the associations of laboratory assessments and National Comprehensive Cancer Network International Prognostic Index (NCCN-IPI) risk groups with progression-free survival (PFS) and overall survival (OS).

RESULTS

Pretreatment anemia, elevated pretreatment CRP levels, and higher risk NCCN-IPI groups were significantly associated with reduced PFS and OS (P = .001 and P = .003 for pretreatment anemia, P = .035 and P = .029 for elevated CRP, and P < .001 and P < .001 for higher risk NCCN-IPI groups). On multivariate Cox regression analysis, only the NCCN-IPI risk group remained as an independent significant predictor for PFS (P < .001) and OS (P < .001). In the subgroup of patients in complete remission 6 months after chemotherapy (n = 80), 6-month posttreatment anemia was significantly associated with reduced PFS (P = .046) but not OS (P = .062), and higher risk NCCN-IPI groups were significantly associated with both reduced PFS (P = .008) and OS (P = .017). On multivariate Cox regression analysis, only the NCCN-IPI group remained an independent significant predictor for PFS (P = .008) and OS (P = .017).

CONCLUSION

Pretreatment anemia, pretreatment CRP levels, and 6-month posttreatment anemia are significantly associated with poor outcome, but were not proven to be of additional prognostic value to the current risk stratification index for DLBCL.

Hydroxyurea-induced Pneumonitis in a Patient with Chronic Myelomonocytic Leukemia: An Autopsy Case

We describe the case of an 85-year-old man diagnosed with chronic myelomonocytic leukemia whose disease was treated with hydroxyurea for 3 months. He developed respiratory symptoms that were extensively investigated. Despite the intensive treatment, he died of respiratory failure eleven days later. An autopsy revealed diffuse interstitial inflammation of both lungs consistent with drug-induced inflammation. A drug lymphocyte stimulation test was positive for hydroxyurea. Taken together these findings demonstrated that severe interstitial pneumonitis was induced by this drug. Physicians using hydroxyurea must be aware of its potentially life-threatening pulmonary toxicity.

Natural history of chronic myelomonocytic leukemia: gene sequencing identifies multiple clonal molecular abnormalities associated with rapid progression to acute myeloid leukemia

Key Clinical Message

Gene panel sequencing in a CMML patient without any detectable genetic abnormality by conventional genetic studies identified four concurrent somatic mutations in three genes. Gene panel mutation analysis is a rapidly emerging clinical tool to demonstrate the clonality in hematologic malignancies, and to identify the potential targets for therapy.

Expressive aphasia in a patient with chronic myelomonocytic leukemia

Various paraneoplastic autoimmune phenomena have been reported in patients with myelodysplastic syndromes. We describe a patient who developed expressive aphasia as a paraneoplastic complication of chronic myelomonocytic leukemia (CMML). Awareness of the various possible manifestations of CMML may aid in the early recognition of the condition.

Chronic myelomonocytic leukemia prognostic classification and management: evidence base and current practice

Chronic myelomonocytic leukemia is a clonal malignancy of the ageing hematopoietic stem cell characterized by a biased differentiation leading to persistent monocytosis and inconstant hypersensitivity of myeloid progenitors to granulo-monocyte colony-stimulating factor (GM-CSF). Cytogenetic abnormalities identified in 30-40 % of patients and gene mutations detected in every patient can be used to stratify patients into risk groups that guide the therapeutic choices. TET2, SRSF2, ASXL1, and genes of the Ras pathway are the most frequently mutated genes, with ASXL1 mutations negatively affecting the disease outcome. Allogeneic stem cell transplantation is the first option to consider, especially in younger patients with poor prognostic factors. There is no firm clinical guideline in transplant-ineligible patients, but hypomethylating agents might be an interesting option. A consensus prognostic scoring system and specific response criteria are now required to facilitate the evaluation of new therapeutic strategies in clinical trials specifically dedicated to this disease.

Cytogenetic risk stratification of 417 patients with chronic myelomonocytic leukemia from a single institution

Approximately 30% of patients with chronic myelomonocytic leukemia (CMML) have karyotypic abnormalities and this low frequency has made using cytogenetic data for the prognostication of CMML patients challenging. Recently, a three-tiered cytogenetic risk stratification system for CMML patients has been proposed by a Spanish study group. Here we assessed the prognostic impact of cytogenetic abnormalities on overall survival (OS) and leukemia-free survival (LFS) in 417 CMML patients from our institution. Overall, the Spanish cytogenetic risk effectively stratified patients into different risk groups, with a median OS of 33 months in the low-, 24 months in intermediate- and 14 months in the high-risk groups. Within the proposed high risk group, however, marked differences in OS were observed. Patients with isolated trisomy 8 showed a median OS of 22 months, similar to the intermediate-risk group (P = 0.132), but significantly better than other patients in the high-risk group (P = 0.018). Furthermore, patients with more than three chromosomal abnormalities showed a significantly shorter OS compared with patients with three abnormalities (8 vs. 15 months, P = 0.004), suggesting possible a separate risk category. If we simply moved trisomy 8 to the intermediate risk category, the modified cytogenetic grouping would provide a better separation of OS and LFS; and its prognostic impact was independent of other risk parameters. Our study results strongly advocate for the incorporation of cytogenetic information in the risk model for CMML.