New agents in the treatment of childhood leukemias and myelodysplastic syndromes

Relapsed or refractory leukemia remains the most common therapeutic problem in pediatric oncology. Particularly challenging is the patient who has recurrence following a stem cell transplant. Insights into the molecular pathogenesis of the leukemias have produced an array of new agents. These new agents will be more selective in hitting their targets, and so their use will be more narrowly defined than with classical cytotoxic drugs. These new agents include all-trans retinoic acid, gemtuzumab ozogamicin, imatinib mesylate, rituximab, and a bevy of signal transduction inhibitors and therapeutic monoclonal antibodies. Other new agents, such as liposomal daunorubicin, PEG-asparaginase, or clofarabine, represent chemical modifications of established antileukemic drugs. Increasingly, molecular profiling will be used to guide the development and application of new drugs.     

Efficacy of hypomethylating agents in therapy-related myelodysplastic syndromes

We retrospectively assessed morphologic and cytogenetic responses to 5-azacytidine and decitabine in a cohort of 42 adult therapy-related myelodysplastic syndromes (tMDS) patients treated at Memorial Sloan-Kettering Cancer Center and in 2 industry-sponsored decitabine trials (D0007 and DACO-020). The overall response rate (complete remission+marrow CR+hematologic improvement) was 38%, including 6 patients with complete remission (14%), 6 with marrow CR with or without hematologic improvement (14%), and 4 with hematologic improvement alone (10%). We conclude that DNA methyltransferase inhibitors showed activity in tMDS that is roughly comparable to that seen in de novo MDS.     

Clinical use of erythropoietic stimulating agents in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are heterogeneous clonal diseases characterized by cytopenias resulting from ineffective hemopoiesis. Anemia affects the vast majority of patients with MDS and contributes substantially to their symptoms. For more than 20 years, recombinant human erythropoietin has been available for clinical use, and it has been employed in an attempt to relieve MDS-related anemia. Erythropoietin-alpha, erythropoietin-beta, and more recently darbepoetin have been found to increase hemoglobin levels and abolish transfusion dependence in 19%-68% of MDS cases. This wide range in clinical response depends on several biological and clinical variables that allow the selection of patients with the highest probability of successful treatment. These agents are a mainstay in MDS therapy, but many issues are still open in terms of the initiation of therapy, the optimal dosage of erythropoietic stimulating agents (ESAs), the most efficient type of ESA, and the duration and outcome of such treatments. In this review, the mechanisms of response and predictive factors as well as an analysis of the clinical activity of ESAs in MDS therapy are presented.     

Hypomethylating agents for the treatment of myelodysplastic syndromes

Azacitidine has been approved in January 2009 in Europe in the treatment of higher-risk myelodysplastic syndromes (MDS). This represents the first time a drug is specifically labelled in MDS in Europe, and is a cornerstone in the development of hypomethylating agents 5-azacytidine (azacitidine) and 5-deoxyazacytidine (decitabine). Clinical trials of hypomethylating agents in MDS still raise a number of questions regarding the precise mode of action of these drugs, as well as the optimal sequencing of treatment in MDS. The positive results of these trials also open the field of epigenetic therapeutic strategies combining hypomethylating agents with other classes of drugs targeting epigenetic processes.     

Differentiating agents in the treatment of leukemia and myelodysplastic syndromes

Differentiation therapies try to change the malignant cell in order to acquire a more mature or normal phenotype. Various ways were tested in leukemia: suppression the proliferative pressure by low dose Ara-C, enhancement of the differentiation by retinoic acid derivatives or by differentiation factors, and modulation of the cell metabolism interrupting an autocrine loop (a growth factor and its receptor). The treatment is given continuously at small doses, during a long period of time. In all these cases it seems necessary to tailor the differentiation therapy to each category of leukemia.     

Novel therapeutic agents for the treatment of myelodysplastic syndromes

Few chemotherapy agents have demonstrated activity in patients with myelodysplastic syndromes (MDS) and supportive management remains the standard of care. An increasing number of new drugs in development are being directed at specific molecular or biological targets of these diseases. Topotecan, a topoisomerase I inhibitor, has shown single-agent activity and is now being combined with other agents, including cytarabine. The aminothiol amifostine induces responses in about 30% of patients; however, its role is still being clarified. Agents that inhibit histone deacetylase and target DNA hypermethylation, thus permitting derepression of normal genes, include 5-azacytidine, decitabine, phenylbutyrate, and depsipeptide. Arsenic trioxide has demonstrated impressive activity in acute promyelocytic leukemia and preclinical data suggest the potential for activity in MDS. UCN-01 is a novel agent that inhibits protein kinase C and other protein kinases important for progression through the G1 and G2 phases of the cell cycle. Dolastatin-10 has extremely potent in vitro activity against a variety of tumor cell lines. Since its dose-limiting toxicities include myelosuppression, it is being studied in acute myelogenous leukemia (AML) and MDS. Ras may play a role in MDS, and activation of this gene and its signaling pathways may require farnesylation. Several farnesyl transferase inhibitors are now available for study in patients with MDS. An increasing body of data suggests a possible role for angiogenesis in MDS, and several antiangiogenesis agents are in clinical trials, including thalidomide, SU5416, and anti-vascular endothelial growth factor (VEGF) antibodies. Development of new drugs and regimens will be facilitated by recently developed standardized response criteria. Future clinical trials should focus on rational combinations of these agents and others with the goal of curing patients with MDS.     

Management of anemia in low-risk myelodysplastic syndromes treated with erythropoiesis-stimulating agents newer and older agents

The myelodysplastic syndromes (MDSs) are clonal hematopoietic stem cell disorders. The International Prognostic Score System (IPSS) groups MDS in lower-risk (IPSS low and intermediate-1) and higher-risk disease (IPSS intermediate-2 and high). AML transformation is the main concern in higher-risk MDS, while anemia and transfusion dependency represent the major issues for low-risk MDS patients. Improving erythropoiesis, and eliminating fatigue and symptoms, is the main therapeutic goal for low-risk MDS patients. Around 50% of MDS patients present with anemia with an Hb level <?100 g/L. Severe anemia increases the negative effects of comorbidities, such as heart and lung failure. Erythropoiesis-stimulating agents (ESAs), with or without granulocyte colony-stimulating factor, induce erythroid response rates in 40–50% of lower-risk anemic MDS patients. The median response duration of 24 months. Apoptosis of erythroid cells is inhibited by ESAs leading to erythrocyte production. Our paper considers the state of the art of treatment of anemia in low-risk MDS patients and the treatment options in MDS resistant or refractory to ESAs.     

Angiogenesis in myelodysplastic syndromes

It is now well established that solid tumour growth depends on angiogenesis. However, less is known about the generation of new vessels in haematological malignancies and, in particular, in preleukaemic-myelodysplastic syndromes (MDS). In this study, bone marrow microvessel density (MVD) was assessed by immunohistochemistry and compared in trephine biopsies from 14 controls, five infectious disease (ID), 82 MDS, 15 acute myeloid leukaemia (AML) and 14 myeloproliferative disorder (MPD) patients. Statistical analysis (P < 0.001) demonstrated that MDS MVD was higher than in controls and ID (21 +/- 9 vs 6 +/- 2 and 10 +/- 8 respectively) but lower than AML (30 +/- 12) and MPD (40 +/- 12). Among MDS-FAB subtypes, MVD was significantly higher in RAEB-t, CMML and fibrosis subsets compared to RA, RARS and RAEB subsets (P= 0.008). To further investigate angiogenesis machinery, the expression of vascular endothelial growth factor (VEGF) was evaluated by means of immunohistochemistry in control, MDS, AML and MPD biopsies. Even though VEGF mRNA expression was reported in the past in AML cell cultures and cell lines, in our samples VEGF expression was found to be particularly strong in most of the megakaryocytes but significantly less prominent in other cell populations including blasts. Since our findings suggest a correlation between angiogenesis and progression to leukaemia, additional work is now warranted to determine what regulates the generation of new vessels in MDS and leukaemia.     

Hematologic outcomes of myelodysplastic syndromes treatment with hypomethylating agents in community practice

IntroductionHypomethylating agents (HMAs) treat myelodysplastic syndromes (MDS) through suppression of abnormal clones that may cause low hemoglobin (Hgb), platelet (PLT) deficiencies, and reduced absolute neutrophil count (ANC). Our study examined hematologic outcomes in MDS among patients treated with HMAs in a large community hematology-oncology practice.Materials and MethodsA retrospective study using electronic medical record data studied patients who received at least one cycle of a single HMA (decitabine [DAC] or azacitidine [AZA]) for MDS from June 1, 2006, to May 31, 2009, who had pretreatment and end-of-treatment Hgb, PLT counts, and ANC available. Multivariate logistic regression assessed predictors of end-of-treatment response (Hgb ≥ 11g/dL without transfusion or erythrocyte stimulating agent; PLT ≥ 100,000 cells/μL without transfusion; ANC ≥ 1000 cells/mm³ without colony stimulating factor) adjusting for baseline laboratory values, age, gender, and comorbidities. HMA choice was studied as a predictor of outcome.ResultsA total of 137 patients (mean age, 72.2 years; 57% male) met full inclusion criteria (DAC = 84, AZA = 53). Mean number of cycles was four (range, 1-16 cycles) for DAC and five (range, 1-23 cycles) for AZA. Total number of cycles significantly predicted Hgb, PLT, and ANC response (odds ratio [OR] 1.19, P = .029; OR 1.15, P = .031; OR 1.16, P = .047, respectively). Growth factor use at any point during HMA treatment was negatively associated with Hgb and ANC response (OR 0.85, P = .007; OR 0.96, P = .046). There was no difference between treatments in likelihood of PLT or ANC response.ConclusionsPatients treated with HMAs for MDS are more likely to achieve hematologic response when treated with a greater number of cycles.     

Pattern of hypomethylating agents use among elderly patients with myelodysplastic syndromes

Little is known about how hypomethylating agents (HMAs) have been adopted into the treatment of myelodysplastic syndromes (MDS). We conducted a population-based study to assess the use of HMAs among 4416 MDS patients (age ≥66 years) who were diagnosed during 2001-2005 and followed up through the end of 2007. Multivariate logistic regression models were utilized to evaluate the role of various patient characteristics. 475 (10.8%) patients had received HMAs by 2007, with the proportion increasing over time. Patients who were white (odds ratio (OR) = 0.66, 95% confidence interval (CI): 0.46-0.95), male (OR = 1.47, 95% CI: 1.19-1.82), young (P_trend < 0.01), more recently diagnosed (OR = 1.90, 95% CI: 1.54-2.34), had fewer comorbidities (P_trend < 0.01), or had a history of other cancer (OR = 1.28, 95% CI: 1.00-1.63) were more likely to receive HMAs. Compared with patients with refractory anemia, those diagnosed with refractory anemia with excess blasts or refractory cytopenia with multilineage dysplasia had a higher chance to be treated with HMAs (OR = 3.52 and 2.32, respectively). Relatively few MDS patients were treated with HMAs during the introduction period of these agents, and multiple patient characteristics such as sex, comorbidities, and MDS subtype influence the likelihood a patient receives HMAs.     

Hypocellular myelodysplastic syndromes

The article is concerned with incidence, clinical features, response to therapy, and prognosis of patients with hypocellular myelodysplastic syndromes. Bone marrow (BM) cellularity <30% (or <20% in patients >70 yr) was found in 24 of 236 (10.2%) trephine biopsies. Median age was 61 yr, with significant male predominance (M/F=3.0) At diagnosis, median hemoglobin was 83 g/L, median platelet and neutrofil counts were 31x109/L and 1.2x109/L, respectively. According to FAB classification, 17 patients had RA, 6 had RAEB, and only 1 had RAEB-t. Beside marrow hypoplasia, the most prominent PH finding was megakaryocyte hypoplasia and dysplasia, found in two-thirds of cases, each. Comparison between hypocellular and normo/hypercellular MDS cases regarding clinicopathological features showed younger age, more severe cytopenia, less blood and BM blast infiltration, MK hypoproliferation, and more pronounced stromal reactions in former cases. Karyotypic abnormalities were present in 12.5% hypocellular cases, in contrast to 44.6% normo/hypercellular cases (p=0.0025). Eleven patients were treated with supportive therapy alone, six with danazol or androgens, six with immunosuppressive therapy, and one with LDARAC. However, complete or partial response was achieved in only four patients treated with danazol or androgens. None of the patients developed leukemia. Eleven patients died, so marrow insufficiency was the main cause of death. Median survival was 33 mo for hypocellular MDS, and 19 mo for normo/hypercellular MDS (p=0.09). The results confirm the existence of hypocellular variant of MDS, which seems to have better prognosis than those patients with normo/hypercellular disease.     

Pediatric myelodysplastic syndromes

Opinion statement A new classification of myelodysplastic and myeloproliferative diseases in childhood has greatly facilitated the diagnosis of these uncommon disorders. Because hematopoietic stem cell transplantation (HSCT) can cure more than half of the affected children, palliative treatment strategies often applied in adult myelodysplastic syndrome (MDS) are of little importance in pediatric MDS. Unraveling some of the underlying genetic factors predisposing to MDS at a young age may give important insights into leukemogenesis in the elderly.     

Thrombocytosis in myelodysplastic and myelodysplastic/myeloproliferative syndromes

Thrombocytosis at diagnosis is uncommon in myelodysplastic (MDS) and myelodysplastic/myeloproliferative (MDS/MPD) syndromes. We conducted a retrospective analysis to determine the clinical and haematopathological features of such patients, and the effect of thrombocytosis on prognosis. Of the 388 patients diagnosed with MDS from 1980 - 2006, 31 presented with thrombocytosis. The majority (71%) had low risk features and a low incidence of spontaneous bleeding or thrombo-embolic events. Compared to a case-matched control group of MDS and MDS/MPD patients without thrombocytosis of similar ages and IPSS scores, patients with thrombocytosis had a slightly lower probability of progression to a higher grade of MDS (P = 0.03), equivalent risk of transformation to acute myeloid leukemia (AML), and a trend (P = 0.07) towards longer overall survival (median 35.4 months compared to 27.6 months for controls).     

New data with arsenic trioxide in leukemias and myelodysplastic syndromes

Arsenic and its derivatives have been used for medicinal purposes for thousands of years. Arsenic trioxide has demonstrated remarkable activity in the treatment of acute promyelocytic leukemia (APL), for which it can bring about complete remissions (CR) in > 80% of patients with relapsed disease, and molecular remission in 90% of those who enter a CR. Clinical trials have explored its use in the first-line setting and as part of consolidation therapy for de novo APL, for which it appears to provide an event-free and overall survival advantage. Two multicenter trials have examined its use in the treatment of the myelodysplastic syndromes; as a single agent, it yields responses in 20% of patients, and smaller trials have provided evidence for its use in non-APL acute myeloid leukemia populations in combination with other drugs such as gemtuzumab ozogamicin, ascorbic acid, and cytarabine.     

Treatment strategies in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a group of disorders characterized by progressive cytopenias and transformation to acute leukemia. Over the last four years, we have experienced a revolution in the treatment of MDS. Three drugs were approved in the U.S. Two of them, 5-azacitidine and 5-aza-2'-deoxycitidine, induce DNA hypomethylation. The third agent, lenalidomide, is a thalidomide analogue with significant activity in a subset of patients with low-risk MDS, anemia and chromosome 5 alterations. Several other agents are being evaluated in MDS. In this short review, we will summarize our current approach to the therapy of patients with MDS.     

Iron overload in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a group of disorders characterized by ineffective hematopoiesis that leads to peripheral cytopenias. Iron overload results from high transfusion requirements and retrospective studies have shown it to be associated with relatively poor survival in a subset of the low risk patients. Recent discoveries have led to the identification of hepcidin as a key regulator of iron metabolism and to the association of non-transferrin bound iron moieties, such as labile plasma iron, with the end organ damage in iron overload states. Currently, there is limited data in evaluating the role of iron chelators in MDS and data from studies in Thalassemia and hemachromostosis have been used to predict ferritin levels above 1000 - 2500 ng/mL and history of 20 blood transfusions as clinical end points for considering iron chelation in MDS. Deferoxamine and deferasirox, the two iron chelators approved for use in the US, have shown efficacy in reducing iron overload in MDS in retrospective studies are now being evaluated for effects on overall survival in prospective studies. On the basis of retrospective data, it is reasonable to offer iron chelation to the lower risk MDS patients requiring frequent transfusions, while monitoring for specific adverse affects in patients on treatment.