Chemotherapy only compared to chemotherapy followed by transplantation in high risk myelodysplastic syndrome and secondary acute myeloid leukemia; two parallel studies adjusted for various prognostic factors

Eligibility for clinical trials is unsatisfactory for patients with myelodysplastic syndromes, even at a tertiary referral center

Participation in clinical trials may allow patients with MDS to gain access to therapies not otherwise available. However, access is limited by strict inclusion and exclusion criteria, reflecting academic or regulatory questions addressed by the respective studies. We performed a simulation in order to estimate the average proportion of MDS patients eligible for participation in a clinical trial. The simulation drew upon 1809 patients in the Düsseldorf MDS Registry whose clinical data allowed eligibility screening for a wide range of clinical trials. This cohort was assumed to be alive and available for study participation. The simulation also posited that all MDS trials (n = 47) conducted in our center between 1987 and 2016 were open for recruitment. In addition, study activities in the year 2016 were analyzed to determine the proportion of patients eligible for at least one of the 9 MDS trials open at that time. On average, each clinical trial was suitable for about 18 % of patients in the simulation cohort. Conversely, 34 % of the patients were eligible for at least one of the 9 clinical studies in 2016. Inclusion/exclusion criteria of studies initiated by the pharmaceutical industry excluded more than twice the fraction of patients compared with investigator initiated trials (potential inclusion of 10 % vs. 21 %, respectively). Karyotype (average exclusion rate 58 %), comorbidities (40 %), and prior therapies (55 %) were the main reasons for exclusion. We suggest that in- and exclusion criteria should be less restrictive, in order to meet the needs of the real-life population of elderly MDS patients.

Infections in Myelodysplastic Syndrome in Relation to Stage and Therapy

Infections remain a significant problem in myelodysplastic syndromes (MDS) in treated as well in non-treated patients and assume a particular complexity. The susceptibility to infections is due, in the absence of intensive chemotherapies, mainly to functional defects in the myeloid lineage with or without neutropenia. Furthermore, MDS includes a heterogeneous group of patients with very different prognosis, therapy and risk factors regarding survival and infections. You should distinguish risk factors related to the disease, like as neutrophils function impairment, neutropenia, unfavorable cytogenetics and bone marrow insufficiency; factors related to the patient, like as age and comorbidities, and factors related to the therapy. When the patients with MDS are submitted to intensive chemotherapy with and without hematopoietic stem cell transplantation (HSCT), they have a risk factor for infection very similar to that of patients with acute myeloid leukemia (AML), and mostly related to neutropenia. Patients with MDS treated with supportive therapy only or with demethylating agent or lenalidomide or immunosuppressive drugs should have a tailored approach. Most of the infections in MDS originate from bacteria, and the main risk factors are represented by neutropenia, thrombocytopenia, and unfavorable cytogenetics. Thus, it is reasonable to give antibacterial prophylaxis to patients who start the therapy with demethylating agents with a number of neutrophils <500 × 10⁹/L, or with thrombocytopenia and unfavorable cytogenetics. The antifungal prophylaxis is not considered cost/benefit adequate and should be taken into consideration only when there is an antecedent fungal infection or presence of filamentous fungi in the surveillance cultures. Subjects submitted to immunosuppression with ATG+CSA have a high rate of infections, and when severely neutropenic should ideally be nursed in isolation, should be given prophylactic antibiotics and antifungals, regular mouth care including an antiseptic mouthwash.

Acute Myeloid Leukemia: The Good, the Bad, and the Ugly

Acute myeloid leukemia (AML) was initially subdivided according to morphology (the French-American-British system), which proved helpful in pathologic categorization. Subsequently, clinical and genomic factors were found to correlate with response to chemotherapy and with overall survival. These included a history of antecedent hematologic disease, a history of chemotherapy or radiation therapy, the presence of various recurrent cytogenetic abnormalities, and, more recently, the presence of specific point mutations. This article reviews the biology and responses of one AML subgroup with consistent response and good outcomes following chemotherapy (core-binding factor leukemia), and two subgroups with persistently bad, and even ugly, outcomes (secondary AML and TP53-mutated AML).

Dose-enhanced combined priming regimens for refractory acute myeloid leukemia and middle-and-high-risk myelodysplastic syndrome: a single-center, retrospective cohort study

Objective

To assess chemotherapeutic regimens for refractory acute myeloid leukemia (AML) and middle-and-high-risk myelodysplastic syndrome (MDS).

Methods

Between 2004 and 2014, 44 patients with refractory AML and 36 patients with MDS were treated with new priming regimens (CHAG, CHTG, CHMG, or CTMG), and 77 patients with refractory AML and 52 patients with MDS were treated with conventional priming regimens (CHG or CAG). This was a single-center retrospective analysis of remission, adverse event, mortality, and survival. The capacity of clinical features (including the expression of co-stimulatory molecule B7.1 on tumor cells) to influence survival was assessed by multivariate Cox regression.

Results

Complete and partial remission rates (RRs) were significantly higher in AML patients treated with new regimens compared to conventional ones (68.2% vs 13.6%, P<0.05). Complete and partial remission were also significantly higher in patients with MDS treated with new regimens (55.6% vs 19.4%, P<0.05). However, although survival advantages were observed in the first year, the new regimens did not significantly improve 3-year overall survival (P>0.05). Patients administered the new regimens experienced more severe and sustained myelosuppression (P<0.05), but no severe adverse events or treatment-related deaths were observed. The rate of non-hematological side effects did not differ significantly between treatment regimens (P>0.05). Both RR and B7.1 expression were significantly higher in patients with AML-M2 and M5 (P<0.05).

Conclusion

The new priming regimens improved the RR, lowered the recurrence rate, and improved survival in AML and middle-and-high-risk MDS, without significantly increasing adverse events.

Efficacy and safety of homoharringtonine plus cytarabine and aclarubicin for patients with myelodysplastic syndrome-RAEB

The aim of the present study was to evaluate the treatment outcome of homoharringtonine, cytarabine (AraC) and aclarubicin combination therapy as induction treatment for myelodysplastic syndromes-refractory anemia with excess blasts (MDS-RAEB). A total of 24 patients with MDS-RAEB who were aged between 18 and 66 years were treated with homoharringtonine, AraC and aclarubicin (HAA regimen). The HAA regimen consisted of homoharringtonine (2 mg/m² intramuscularly twice daily, days 1-3), AraC (75 mg/m² injected subcutaneously twice daily, days 1-7) and aclarubicin (12 mg/m², days 1-7). The overall response rate was 79% with a complete remission rate of 58.3% and partial remission rate of 20.7%. There was no evidence of early mortality in this group of patients. The median overall survival (OS) was 36.2 months (95% confidence interval, 24.6-47.4 months), and the estimated three year overall survival rate was 45.8%. In conclusion, HAA combination therapy is a suitable induction regimen for patients with MDS-RAEB, which may improve the outcome for de novo higher-risk MDS patients, particularly of those with favorable and intermediate cytogenetics.

Stopping higher-risk myelodysplastic syndrome in its tracks

Higher-risk myelodysplastic syndromes (MDS) are a collection of diseases associated with poor outcomes from complications related to bone marrow failure and evolution to acute myeloid leukemia. While most patients receive epigenetic therapies, intensive chemotherapy or allogeneic stem cell transplantation, more tolerable and effective treatments are necessary to realize the goal of stopping this disease in its tracks. Recent efforts, building on decades of research exploring the pathogenesis of this disease, have revealed exciting clues that elucidate critical biological features that drive or contribute to MDS, and may serve as targets for selective and well-tolerated future therapies. Here, we review the current diagnostic, prognostic, and therapeutic approaches to higher-risk MDS.

Myelodysplastic syndrome evolving from aplastic anemia treated with immunosuppressive therapy: efficacy of hematopoietic stem cell transplantation

A proportion of patients with aplastic anemia who are treated with immunosuppressive therapy develop clonal hematologic disorders, including post-aplastic anemia myelodysplastic syndrome. Many will proceed to allogeneic hematopoietic stem cell transplantation. We identified 123 patients with post-aplastic anemia myelodysplastic syndrome who from 1991 through 2011 underwent allogeneic hematopoietic stem cell transplantation, and in a matched-pair analysis compared outcome to that in 393 patients with de novo myelodysplastic syndrome. There was no difference in overall survival. There were no significant differences with regard to 5-year probabilities of relapse, non-relapse mortality, relapse-free survival and overall survival; these were 14%, 40%, 46% and 49% for post-aplastic anemia myelodysplastic syndrome, and 20%, 33%, 47% and 49% for de novo myelodysplastic syndrome, respectively. In multivariate analysis, relapse (hazard ratio 0.71; P=0.18), non-relapse mortality (hazard ratio 1.28; P=0.18), relapse-free survival (hazard ratio 0.97; P=0.80) and overall survival (hazard ratio 1.02; P=0.88) of post-aplastic anemia myelodysplastic syndrome were similar to those of patients with de novo myelodysplastic syndrome. Cytogenetic risk was independently associated with overall survival in both groups. Thus, transplant success in patients with post-aplastic anemia myelodysplastic syndrome was similar to that in patients with de novo myelodysplastic syndrome, and cytogenetics was the only significant prognostic factor for post-aplastic anemia myelodysplastic syndrome patients.

Myelodysplastic syndromes: toward a risk-adapted treatment approach

Several classification and scoring systems have been developed in myelodysplastic syndromes (MDS to predict the risk of progression to acute myeloid leukemia and survival. These prognostication models have been also used to inform therapeutic decision-making in a risk-adapted fashion. Patient-related factors such as age, comorbidities, and functional status have to be considered as well. Here we review a risk-guided therapeutic approach for the management of MDS patients. It is anticipated that the improved understanding of the complex pathogenesis of MDS and the recent discovery of important molecular lesions will be translated into novel therapeutic approaches. Additionally, some prognostic aberrations are expected to be incorporated into the prognostic tools with the goal of improving their prognostic precision and therefore allow for a more informed therapeutic decision-making based on the individual's risk profile.

Diagnosis and treatment of primary myelodysplastic syndromes in adults: recommendations from the European LeukemiaNet

Within the myelodysplastic syndrome (MDS) work package of the European LeukemiaNet, an Expert Panel was selected according to the framework elements of the National Institutes of Health Consensus Development Program. A systematic review of the literature was performed that included indexed original papers, indexed reviews and educational papers, and abstracts of conference proceedings. Guidelines were developed on the basis of a list of patient- and therapy-oriented questions, and recommendations were formulated and ranked according to the supporting level of evidence. MDSs should be classified according to the 2008 World Health Organization criteria. An accurate risk assessment requires the evaluation of not only disease-related factors but also of those related to extrahematologic comorbidity. The assessment of individual risk enables the identification of fit patients with a poor prognosis who are candidates for up-front intensive treatments, primarily allogeneic stem cell transplantation. A high proportion of MDS patients are not eligible for potentially curative treatment because of advanced age and/or clinically relevant comorbidities and poor performance status. In these patients, the therapeutic intervention is aimed at preventing cytopenia-related morbidity and preserving quality of life. A number of new agents are being developed for which the available evidence is not sufficient to recommend routine use. The inclusion of patients into prospective clinical trials is strongly recommended.

Current therapy of myelodysplastic syndromes

After being a neglected and poorly-understood disorder for many years, there has been a recent explosion of data regarding the complex pathogenesis of myelodysplastic syndromes (MDS). On the therapeutic front, the approval of azacitidine, decitabine, and lenalidomide in the last decade was a major breakthrough. Nonetheless, the responses to these agents are limited and most patients progress within 2 years. Allogeneic stem cell transplantation remains the only potentially curative therapy, but it is associated with significant toxicity and limited efficacy. Lack or loss of response after standard therapies is associated with dismal outcomes. Many unanswered questions remain regarding the optimal use of current therapies including patient selection, response prediction, therapy sequencing and combinations, and management of resistance. It is hoped that the improved understanding of the underpinnings of the complex mechanisms of pathogenesis will be translated into novel therapeutic approaches and better prognostic/predictive tools that would facilitate accurate risk-adaptive therapy.

Over-expression of RPL23 in myelodysplastic syndromes is associated with apoptosis resistance of CD34+ cells and predicts poor prognosis and distinct response to CHG chemotherapy or decitabine

Ribosomal protein (RP) L23 has been suggested to be a negative regulator of cell apoptosis. In the present study, we analyzed RPL23 expression in 169 patients with myelodysplastic syndrome (MDS) by using real-time PCR. The apoptosis of CD34(+) marrow cells was examined by flow cytometry, and the correlation between RPL23 expression levels and apoptosis in CD34(+) cells was assessed. We then analyzed the clinical significance of RPL23 expression for predicting disease progression and patient survival as well as therapeutic response in patients administered with a cytarabine, homoharringtonine, and G-CSF (CHG) regimen or decitabine therapy. Increased RPL23 expression was found in patients with higher-risk MDS than in patients with lower-risk disease (p = 0.004). RPL23 expression levels were found being inversely correlated with decreased apoptotic ratio of CD34(+) cells in higher-risk patients (r = -0.672, p < 0.001). Compared to patients with normal RPL23 expression levels, those with increased RPL23 expression presented higher rates of transformation to acute myeloid leukemia (p = 0.005) and reduced 2-year survival rates (p = 0.012). Multivariate regression analysis showed that RPL23 expression level was an independent predictor of prognosis, regardless of patient age, IPSS score, or hemoglobin level. Moreover, patients with RPL23 over-expression appeared to have lower response rates to CHG chemotherapy (p = 0.027) but similar response rates to decitabine treatment. In conclusion, the over-expression of RPL23 might confer apoptosis resistance in CD34(+) cells, which may lead to disease progression and adverse prognosis in MDS. Increased RPL23 expression was an inverse indicator for CHG regimen, but not for decitabine treatment.

Hematopoietic stem cell transplantation for myelodysplastic syndrome: a review

Allogeneic hematopoietic stem cell transplantation (HSCT) continues to be the only curative option for myelodysplastic syndrome (MDS). Since the majority of the patients with this disease are often older and frail, treatment-related mortality and morbidity remain major obstacles to be overcome. Reduced-intensity conditioning and continued lines of investigation in the field of allogeneic transplantation are expected to ultimately improve the overall therapeutic approach to MDS. In this review we summarize current recommendations and controversies surrounding HSCT for MDS, as well as the use of novel therapeutics in the peri-transplant period.

Efficacy and safety of CHG regimen (low-dose cytarabine, homoharringtonine with G-CSF priming) as induction chemotherapy for elderly patients with high-risk MDS or AML transformed from MDS

BACKGROUND

To evaluate the efficacy and toxicity of CHG regimen (low-dose cytarabine, homoharringtonine with G-CSF priming) as an induction chemotherapy for elderly patients with high-risk MDS or acute myeloid leukemia transformed from MDS (MDS-AML).

METHODS

Thirty-three untreated patients (21 high-risk MDS and 12 MDS-AML) were enrolled in this study. Each patient was administered with the CHG regimen comprised of low-dose cytarabine (25 mg/day, days 1-14) and homoharringtonine (1 mg/day, days 1-14) by intravenous continuous infusion in combination with G-CSF (300 μg/day) by subcutaneous injection from day 0 until neutrophil count recovery to 2.0 × 10(9)/L.

RESULTS

The overall response rate (OR) was 66.7% after one course of the CHG regimen with 19 patients reaching CR (57.6%) and 3 patients reaching partial remission (PR) (9.1%). The median overall survival (OS) was 15.0 months. Patients with normal serum lactate dehydrogenase (LDH) appeared longer median OS when compared to patients with high LDH level (18 months vs. 5 months, P = 0.011). Grade 3/4 thrombocytopenia occurred in 28% of patients, neutropenia in 34%. No treatment-related deaths occurred during the induction therapy.

CONCLUSIONS

These data suggest that the CHG priming regimen is effective and safe as a novel induction therapy for elderly patients with high-risk MDS and MDS-AML. The results need to be conformed in further study involving a larger cohort of patients.

Effect of low-dose cytarabine, homoharringtonine and granulocyte colony-stimulating factor priming regimen on patients with advanced myelodysplastic syndrome or acute myeloid leukemia transformed from myelodysplastic syndrome

A total of 32 patients (25 with advanced MDS and 7 with t-AML) were enrolled in this study to evaluate the efficacy and toxicity of the low-dose cytarabine and homoharringtonine in combination with granulocyte colony-stimulating factor (G-CSF) (CHG protocol) in patients with advanced myelodysplastic syndromes (MDS) or MDS-transformed acute myeloid leukemia (t-AML). All the patients were administered the CHG regimen comprising low-dose cytarabine (25 mg/day, intravenous continuous infusion, days 1-14), homoharringtonine (1 mg/day, intravenous continuous infusion, days 1-14), and G-CSF (300 microg/day, subcutaneous injection, days 0-14, interrupted when the peripheral white blood cell count reached >20 x 10(9)/L). The overall response rate was 71.9% after the administration of one course of the CHG regimen. Of the 32 patients, 15 (46.9%) achieved complete remission (CR) and 8 (25%) achieved partial remission (PR). This regimen was followed by a post-remission therapy that included conventional chemotherapy, when CR was achieved. Of the patients with CR who just received post-remission regimens as homoharringtonine and cytarabine (HA) and daunorubicin and cytarabine (DA) 6 relapsed rapidly and just had a mean 6.1 months of CR. Otherwise, the other 8 out of 14 patients with CR alternatively received subsequent chemotherapy, which combined mitoxantrone, idarubicin, pirarubicin, or aclarubicin with cytarabine. The mean CR duration of the 8 patients had reached 10.6 months, and 5 of the 8 still kept a continuous CR. The median overall survival (OS) was 18.2 months. There were no statistically significant differences for CR, PR, and OS when the patients were grouped by age, blasts in bone marrow, and karyotypes, respectively. No treatment-related deaths were observed. Myelosuppression was mild to moderate, and no severe non-hematological toxicity was observed. Thus, a CHG priming regimen as an induction therapy was well tolerated and effective in patients with advanced MDS or t-AML. Stronger and alternative subsequent chemotherapy is necessary for patients with CR to maintain longer CR and better OS.

Review of stem-cell transplantation for myelodysplastic syndromes in older patients in the context of the Decision Memo for Allogeneic Hematopoietic Stem Cell Transplantation for Myelodysplastic Syndrome emanating from the Centers for Medicare and Medicaid Services

Myelodysplastic syndromes (MDS) comprise a heterogeneous group of clonal hematopoietic stem-cell disorders that result in varying degrees of cytopenia and risk of transformation into acute leukemia. Allogeneic stem-cell transplantation (SCT) is the only known cure for this disease. The treatment is routinely used for younger patients, but only a minority of patients older than the age of 60 undergo this procedure. The overall MDS incidence is 3.3 per 100,000, but the incidence in patients older than age 70 is between 15 and 50 per 100,000. The median age at presentation is 76 years. Medicare-age patients 65 or older represent 80% of the total population receiving an MDS diagnosis. In the United States, one of the obstacles to SCT for older patients with MDS has been lack of third party reimbursement. On August 4, 2010, the Centers for Medicare and Medicaid Services released their Decision Memo for Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) for Myelodysplastic Syndrome. This memo states: "Allogeneic HSCT for MDS is covered by Medicare only for beneficiaries with MDS participating in an approved clinical study that meets the criteria below…. " In this review, we will summarize what is known regarding the role of allogeneic SCT in older patients as well as other elements that should be included within clinical trials that can provide the evidence necessary to demonstrate that allogeneic SCT should be a covered benefit for Medicare beneficiaries.

High-risk myelodysplastic syndromes: chemotherapy, transplantation, and beyond

Allogeneic hematopoietic cell transplantation (HCT) has curative potential for patients with myelodysplastic syndromes (MDS), though with considerable nonrelapse mortality and morbidity. The International Prognostic Scoring System, despite its confines, remains a widely used tool guiding treatment decisions in MDS. The two hypomethylating agents, 5-azacytidine (azacitidine) and 5-aza-2-deoxycytidine (decitabine), are both effective in high-risk MDS, but about 50% of high-risk MDS patients fail to achieve a meaningful response, and these agents offer only a modest survival benefit, with a median response duration of 13 months. The more recent proposed risk models of MDS, as well as modern transplant strategies and expanded alternative donor sources, have helped to increase the number of patients offered curative treatment. As both drug therapy and HCT modalities evolve, treatment decisions are certain to become more complex. Current therapeutic options should view the hypomethylating agents as a way to optimize disease response before (and possibly after) HCT.

Value of allogeneic versus autologous stem cell transplantation and chemotherapy in patients with myelodysplastic syndromes and secondary acute myeloid leukemia. Final results of a prospective randomized European Intergroup Trial

BACKGROUND

Allogeneic stem cell transplantation is usually considered the only curative treatment option for patients with advanced or transformed myelodysplastic syndromes in complete remission, but post-remission chemotherapy and autologous stem cell transplantation are potential alternatives, especially in patients over 45 years old.

DESIGN AND METHODS

We evaluated, after intensive anti-leukemic remission-induction chemotherapy, the impact of the availability of an HLA-identical sibling donor on an intention-to treat basis. Additionally, all patients without a sibling donor in complete remission after the first consolidation course were randomized to either autologous peripheral blood stem cell transplantation or a second consolidation course consisting of high-dose cytarabine.

RESULTS

The 4-year survival of the 341 evaluable patients was 28%. After achieving complete remission, the 4-year survival rates of patients under 55 years old with or without a donor were 54% and 41%, respectively, with an adjusted hazard ratio of 0.81 (95% confidence interval [95% CI], 0.49-1.35) for survival and of 0.67 (95% CI, 0.42-1.06) for disease-free survival. In patients with intermediate/high risk cytogenetic abnormalities the hazard ratio in multivariate analysis was 0.58 (99% CI, 0.22-1.50) (P=0.14) for survival and 0.46 (99% CI, 0.22-1.50) for disease-free survival (P=0.03). In contrast, in patients with low risk cytogenetic characteristics the hazard ratio for survival was 1.17 (99% CI, 0.40-3.42) and that for disease-free survival was 1.02 (99% CI, 0.40-2.56). The 4-year survival of the 65 patients randomized to autologous peripheral blood stem cell transplantation or a second consolidation course of high-dose cytarabine was 37% and 27%, respectively. The hazard ratio in multivariate analysis was 1.22 (95% CI, 0.65-2.27) for survival and 1.02 (95% CI, 0.56-1.85) for disease-free survival.

CONCLUSIONS

Patients with a donor and candidates for allogeneic stem cell transplantation in first complete remission may have a better disease-free survival than those without a donor in case of myelodysplastic syndromes with intermediate/high-risk cytogenetics. Autologous peripheral blood stem cell transplantation does not provide longer survival than intensive chemotherapy.

Outcomes of patients who undergo aggressive induction therapy for secondary acute myeloid leukemia

BACKGROUND

Response and survival in 96 patients with secondary acute myeloid leukemia (sAML) who received aggressive induction chemotherapy was reviewed.

METHODS

The median follow-up of survivors was 2.3 years. A total of 70 (73%) patients achieved a morphologic complete remission (CR) confirmed by absence of leukemic blasts by flow cytometry.

RESULTS

For all 96 patients, the median event-free survival (EFS) was 8 months, and overall survival (OS) was 13.6 months (range, 1-119 months). Eight patients died shortly after induction therapy because of disease or side effects, and 13 are currently in continuous first remission. The median disease-free survival (DFS) for all 70 patients who achieved a morphologic CR was 9 months (range, 1-51 months), with a 64% chance of surviving 1 year. Patients with AML after previous chemotherapy or radiation therapy had a higher morphologic remission rate compared with those arising from myelodysplastic syndrome or myeloproliferative disease (82% vs 62%; P = .027). However, among the patients from the 2 groups who attained a morphologic remission, there was no difference in terms of CR rate (P = .94), DFS, EFS, or OS (P = .55, .83, and .71, respectively). This is a similar DFS to the group of 7 patients who went directly to ablative allogeneic transplant rather than having induction therapy first. In this population of patients who received aggressive chemotherapy, Charlson comorbidity index or a higher number of factors recognized as high risk in leukemia patients did not affect the chance of OS, DFS, and EFS, although having more recognized leukemia risk factors was related to a lower chance of surviving 1 year. However, it is important to note that those with higher comorbidity indexes were underrepresented in this aggressively treated cohort.

CONCLUSIONS

The data from the current study demonstrate that many patients with sAML can tolerate aggressive induction therapy and attain remission, but duration of response and the chance of long-term survival remain poor.

The role of cytotoxic therapy with hematopoietic stem cell transplantation in the therapy of myelodysplastic syndromes: an evidence-based review

Clinical research examining the role of hematopoietic stem cell transplantation (SCT) in the therapy of myelodysplastic syndromes (MDS) in adults is presented and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published literature and for grading the quality and strength of the evidence and the strength of the treatment recommendations. Treatment recommendations based on the evidence are presented in Table 3, and were reached unanimously by a panel of MDS experts. The identified priority areas of needed future research in MDS include: (1) the benefit of using alternative donor sources (eg, cord blood; haploidentical family donors) for patients without matched sibling or unrelated donors; (2) the role and appropriate timing of allogeneic SCT in combination with hypomethylating and immunomodulatory treatment regimens; (3) randomized trials comparing the safety and efficacy of various novel agents for treating MDS; and (4) the influence of the various MDS treatment modalities on patient-reported quality-of-life outcomes.

Negative effect of DNA hypermethylation on the outcome of intensive chemotherapy in older patients with high-risk myelodysplastic syndromes and acute myeloid leukemia following myelodysplastic syndrome

PURPOSE

Promoter hypermethylation of, for example, tumor-suppressor genes, is considered to be an important step in cancerogenesis and a negative risk factor for survival in patients with myelodysplastic syndromes (MDS); however, its role for response to therapy has not been determined. This study was designed to assess the effect of methylation status on the outcome of conventional induction chemotherapy.

EXPERIMENTAL DESIGN

Sixty patients with high-risk MDS or acute myeloid leukemia following MDS were treated with standard doses of daunorubicin and 1-beta-d-arabinofuranosylcytosine. Standard prognostic variables and methylation status of the P15(ink4b) (P15), E-cadherin (CDH), and hypermethylated in cancer 1 (HIC) genes were analyzed before treatment.

RESULTS

Forty percent of the patients achieved complete remission (CR). CR rate was lower in patients with high WBC counts (P = 0.03) and high CD34 expression on bone marrow cells (P = 0.02). Whereas P15 status alone was not significantly associated with CR rate (P = 0.25), no patient with hypermethylation of all three genes achieved CR (P = 0.03). Moreover, patients with CDH methylation showed a significantly lower CR rate (P = 0.008), and CDH methylation retained its prognostic value also in the multivariate analysis. Hypermethylation was associated with increased CD34 expression, but not with other known predictive factors for response, such as cytogenetic profile.

CONCLUSIONS

We show for the first time a significant effect of methylation status on the outcome of conventional chemotherapy in high-risk MDS and acute myelogenous leukemia following MDS. Provided confirmed in an independent study, our results should be used as a basis for therapeutic decision-making in this patient group.

Outcome of patients who develop acute leukemia or myelodysplasia as a second malignancy after solid tumors treated surgically or with strategies that include chemotherapy and/or radiation

BACKGROUND

Evaluation of therapeutic outcomes and risk factors was undertaken for patients with primary solid tumors (PST) developing acute leukemia or myelodysplasia (MDS) as a second malignancy.

METHODS

In all, 131 consecutive patients presenting to a single institution with leukemia or MDS after treatment for PST with surgery or chemotherapy/radiotherapy were examined. Management of the secondary acute leukemia and MDS consisted either of intensive therapy including allogeneic blood and marrow transplants or supportive measures.

RESULTS

The time from diagnosis of PST to development of acute leukemia or MDS, the cytogenetic profile of patients, and their survival were similar irrespective of PST therapy with surgery alone or strategies involving chemotherapy and/or radiation. The median survival of all 131 patients was 10.5 months with a 5-year survival of 15.6%. Induction therapy and/or transplantation resulted in a median survival of 13.6 months and a 5-year survival of 26.6% compared with 6.5 months and 2% with supportive measures. Subset analysis of transplant recipients revealed a median survival of 17.6 months and a 37.9% 5-year survival. Despite a significantly lower recurrence rate the survival of transplant recipients was not improved secondary to a higher treatment-related mortality (TRM) rate.

CONCLUSIONS

Patients developing acute leukemia or MDS after PST demonstrated similar cytogenetic profiles and clinical outcomes independent of the type of treatment. Survival was significantly better for patients able to undergo intensive therapy compared with supportive measures. The low recurrence rate for allograft recipients was consistent with a potent antileukemic effect that may translate into a survival benefit if TRM could be reduced.

Allogeneic stem cell transplantation for myelodysplastic syndrome

Although it is only used to treat a minority of patients with myelodysplastic syndromes, stem cell transplantation (SCT) is the only proven curative treatment for this condition. Because MDS occurs in a population of older adults with significant comorbidities, reduced-intensity conditioning (RIC) regimens have been particularly important in extending safe SCT to the large MDS population over the age of 60 years. Extension of the unrelated donor pool together with the introduction of umbilical cord blood transplants in adults has extended the number of patients with suitable donors. Nevertheless overall mortality from SCT is greater than 50% because of relapse and non-relapse mortality (NRM). New developments to improve outcome include the tailoring of the transplant approach to the individual based on age and comorbidity, and the use of pretransplant chemotherapy to reduce disease bulk prior to transplant, as well as the introduction of post-transplant immunotherapy (pre-emptive donor lymphocyte infusions) and chemotherapy to prevent relapse. Further improvements in transplant outcome await better ways to reconstitute immunity and amplify the graft-versus-leukemia (GVL) effect without causing graft-versus-host disease (GVHD), as well as further extension of the donor pool and exploration of risk-adapted regimens for the population of MDS in their seventh to eighth decade.

Therapy-related acute myelogenous leukemia and myelodysplastic syndrome

Therapy-related acute myelogenous leukemia and myelodysplastic syndrome (t-AML/MDS) are increasing in prevalence with aging of the population and improved survival of patients treated with chemotherapy or radiotherapy for other malignancies. Research focused on the pathogenesis of t-AML/MDS will provide insight into the pathogenesis of de novo AML/MDS. Participation in clinical trials should be encouraged for this patient population because results with available treatment options are clearly suboptimal.

Sequential flavopiridol, cytosine arabinoside, and mitoxantrone: a phase II trial in adults with poor-risk acute myelogenous leukemia

PURPOSE

Flavopiridol is a cyclin-dependent kinase inhibitor that is cytotoxic to leukemic blasts. In a phase I study of flavopiridol followed by 1-beta-d-arabinofuranosylcytosine (ara-C) and mitoxantrone, overall response rate for adults with relapsed and refractory acute myelogenous leukemias (AML) was 31%. We have now completed a phase II study of sequential flavopiridol, ara-C, and mitoxantrone in 62 adults with poor-risk AML.

EXPERIMENTAL DESIGN

Flavopiridol (50 mg/m(2)) was given by 1-h infusion daily x 3 beginning day 1 followed by 2 gm/m(2)/72 h ara-C beginning day 6 and 40 mg/m(2) mitoxantrone on day 9.

RESULTS

Flavopiridol caused a > or =50% decrease in peripheral blood blasts in 44% by median day 2 and > or =80% decrease in 26% by day 3. Self-limited tumor lysis occurred in 53%. Three (5%) died during therapy (2 multiorgan failure and 1 fungal pneumonia). Complete remissions (CR) were achieved in 12 of 15 (75%) newly diagnosed secondary AML, 18 of 24 (75%) first relapse after short CR (median CR, 9 months, including prior allotransplant), and 2 of 13 (15%) primary refractory but 0 of 10 multiply refractory AML. Disease-free survival for all CR patients is 40% at 2 years, with newly diagnosed patients having a 2-year disease-free survival of 50%.

CONCLUSIONS

Flavopiridol has anti-AML activity directly and in combination with ara-C and mitoxantrone. This timed sequential regimen induces durable CRs in a significant proportion of adults with newly diagnosed secondary AML (including complex cytogenetics) and adults with AML in first relapse after short first CR.

A retrospective comparison of autologous and unrelated donor hematopoietic cell transplantation in myelodysplastic syndrome and secondary acute myeloid leukemia: a report on behalf of the Chronic Leukemia Working Party of the European Group for Blood and Marrow Transplantation (EBMT)

Hematopoietic cell transplantation (HCT) is an effective treatment for myelodysplasia (MDS) and secondary acute myeloid leukemia (sAML). In this study, outcome of 593 patients with MDS/sAML after autologous and allogeneic HCT from a matched unrelated donor (MUD) were compared. A total of 167 (28%) patients received HCT from MUD without prior chemotherapy (MUD-U). The rest received HCT in first complete remission (CR1) (Autologous (Auto-CR1), n=290 (49%), HCT from MUD (MUD-CR1), n=136 (23%)). Survival at 3 years was best in MUD-CR1 (50%) compared to Auto-CR1 (41%) and MUD-U (40%) (P=0.01). Similarly, disease-free survival was 44% for MUD-CR1 compared to Auto-CR1 (28%) and MUD-U (34%) (P=0.03). Treatment-related mortality was 17% in Auto-CR1 compared to MUD-CR1 (38%) and MUD-U (49%) (P<0.001). Relapse for Auto-CR1 was 62% compared to 24 and 30% for MUD-CR1 and MUD-U, respectively (P<0.001). Outcome was best for patients with low tumor burden transplanted 6-12 months after diagnosis. Factors influencing outcome at 3 years were mainly significant in the first 6 months. Only, relapse after autologous HCT remained constant over time. Outcomes after allogeneic HCT in patients of 20-40 and >40 years were similar. Autologous and Allogeneic HCT from MUD offer the possibility of long-term survival to patients with MDS/sAML.

Autologous and allogeneic stem cell transplantation for myelodysplastic syndrome

Allogeneic stem cell transplantation (alloSCT) is the treatment of choice in the majority of young patients with advanced stages MDS if they have a suitable donor. Since outcome of transplantation is superior for patients with a low blast percentage, this supports the use of chemotherapy prior to transplantation in patients with high blast marrow infiltration. The allogeneic transplant procedure continues to carry a high treatment-related risk, but results have improved progressively over the years. The transplantation results using phenotypically matched voluntary unrelated donors have improved impressingly, mainly due to significantly reduced transplantation-related mortality rate. The upper age limit for transplantation has moved to 65-70 years after the introduction of reduced intensity conditioning regimens (RIC). The place of RIC remains to be determined also in older patients in view of the associated higher relapse risk. For patients lacking a suitable donor the choice is ambiguous. Although the number of reports on autologous stem cell transplantation is still limited, the outcome seems similar to allogeneicSCT with donors other than HLA-identical siblings. Further development of accurate prognostic classification systems will allow a risk-adapted strategy for an individual patient.

Aclarubicin and low-dose Cytosine arabinoside in combination with granulocyte colony-stimulating factor in treating acute myeloid leukemia patients with relapsed or refractory disease and myelodysplastic syndrome: a multicenter study of 112 Chinese patients

One hundred twelve patients with geriatric acute myeloid leukemia (AML), refractory or relapsed AML, or myelodysplastic syndrome and refractory anemia with excess of blasts in transformation (MDS-RAEBt) were entered into this study to receive CAG (aclarubicin and low-dose cytosine arabinoside [Ara-C]in combination with granulocyte colony-stimulating factor [G-CSF]) with the objective of evaluating the efficacy and tolerance of this regimen. Low-dose Ara-C was given subcutaneously at a dosage of 10 mg/m2 every 12 hours on days 1 to 14. Aclarubicin was administered intravenously at a dosage of 14 mg/m2 per day on days 1 to 4 (CAG regimen A) or 7 mg/m2 on days 1 to 8 (CAG regimen B). Recombinant G-CSF was given subcutaneously at a dosage of 200 3g/m2 per day on days 1 to 14. We demonstrated comparable overall complete remission rates for the 4 groups of patients: 30.8% (8/26) in the elderly patients, 48.4% (30/62) in the refractory AML patients, 44.4% (8/18) in the relapsed AML patients, and 38.5% (5/13) in the MDS-RAEBt patients. Of the 52 patients followed up, the 12-month progression-free survival (PFS) and overall survival (OS) rates estimated by the Kaplan-Meier method were 40.73% 3 8.15% and 42.85% 3 8.23%, respectively. The median PFS and OS times were 9.0 3 2.2 months and 11.0 3 1.6 months, respectively. Toxic effects were very rare and mainly consisted of neutropenia and thrombocytopenia due to myelosuppression; approximately 70% to 80% of patients had neutropenia or thrombocytopenia that exceeded National Cancer Institute grade II. Nonhematologic toxicities were not observed in this study. The CAG regimen seems promising, with acceptable toxicity, for the treatment of various categories of poor-prognosis AML and MDS-RAEBt.

Management of patients with higher risk myelodysplastic syndromes

Higher risk myelodysplastic syndromes (MDS) include patients in the Intermediate-2 and high-risk categories of the International Prognostic Scoring System, as well as patients with MDS secondary to radiation or chemical exposure. Ideally, the goal of therapy is to alter the natural history of disease in these patients to achieve cure or durable remission. High-intensity chemotherapy can achieve moderate rates of complete remission, however, durability of remission and overall survival tend to be short. Hematopoietic stem cell transplantation (HSCT) offers the possibility of cure, with long-term disease-free survival inversely related to age. Patients who are elderly or have poor functional status are candidates for reduced intensity HSCT, although this is still an experimental modality. Azacitidine is a hypomethylating agent that is a reasonable option for many patients ineligible for high-intensity therapies. Other therapies, such as immunomodulatory agents, arsenic trioxide, and farnesyl transferase inhibitors have thus far shown limited usefulness in higher risk MDS. This paper reviews the various therapeutic options for higher risk MDS, providing rationale for specific management approaches for these patients.

Assessment of the international prognostic scoring system for determining chemotherapeutic indications in myelodysplastic syndrome: Japanese retrospective multicenter study

To standardize a rational therapeutic strategy of chemotherapy using the International Prognostic Scoring System (IPSS), we retrospectively analyzed 292 high-risk myelodysplastic syndrome (MDS) patients in 20 hospitals in Japan. Results of multivariate analysis of the data on patients who received all types of chemotherapy indicated that poor cytogenetics as shown by the IPSS was the only significant risk factor (P = .047). We then focused on the IPSS composition of each patient. The intermediate 2 (Int-2) category consisted of a heterogeneous group. We attempted to subdivide the category into Int-2A and Int-2B. Patients with good or intermediate cytogenetics had > or = 5% bone marrow (BM) blasts (Int-2A), and most of the other patients had poor cytogenetics and < or = 10% BM blasts (Int-2B). In the Int-2B category, overall survival for patients who received chemotherapy was significantly worse than for those who did not receive chemotherapy (P = .005). Most patients in the High category who had the diagnosis of MDS according to the World Health Organization classification had poor overall survival with or without chemotherapy. We propose the Int-2B and High categories may be considered possible high risk, whereas all patients in the Int-2A category and patients with more than 5% BM blasts in the Int-1 category may be categorized as being at possible intermediate risk. Our proposition may be useful for developing a chemotherapeutic strategy for patients with MDS in Japan.

Emerging drugs for the treatment of myelodysplastic syndrome

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal haematopoietic stem cell disorders characterised by ineffective haematopoiesis and an increased risk of developing acute myeloid leukaemia. At present, the only curative option is allogeneic stem cell transplantation. However, the majority of patients are not eligible for this therapy, due to excessive treatment-related morbidity and mortality or lack of a suitable donor. As a result, the need for alternative therapies is great. Our improved understanding of the molecular pathogenesis of MDS has resulted in several new promising therapeutic agents. This review will consider the rational development of new agents based on the molecular biology of MDS.

Secondary acute myeloid leukaemia: results of conventional treatments. Experience of GIMEMA trials

BACKGROUND

The aim of the study was to evaluate the outcome of acute myeloid leukaemia (AML) in patients with a previous malignancy (sAML) treated with chemo- and/or radiotherapy, enrolled in conventional trials.

PATIENTS AND METHODS

In a multicentre setting, a prospective non-concurrent analysis was performed on 2513 new AML patients, aged 12-78 years, consecutively enrolled in EORTC-GIMEMA trials between 1987 and 2001. Thirty-eight patients with sAML were identified and compared with a group of 114 de novo AML patients matched according to age, French-American-British criteria, white blood cell count at diagnosis, trial and time of diagnosis of AML. Induction treatment response, disease-free survival (DFS), duration and overall survival (OS) were evaluated in the two groups.

RESULTS

Comparing the complete remission (CR) rate between 38 sAML patients and 114 de novo AML patients, selected according to the previously reported criteria, we observed no difference in the CR rates [25/38 (66%) versus 66/114 (58%); Pearson chi(2) 0.7393, P=0.390] as well as no differences while comparing the DFS and the OS between the two groups.

CONCLUSION

The results of this study suggest that sAML patients are characterised by a good performance status permitting their recruitment in conventional trials without a previous myelodysplastic phase. Similar to de novo AML patients, sAML patients show good response to treatment and the possibility of cure.

Arsenic trioxide for the treatment of myelodysplastic syndromes

The impressive activity of arsenic trioxide in acute promyelocytic leukaemia (APL) has renewed the interest in this old compound. Arsenic trioxide targets the sulfhydryl groups present in many proteins involved in oncogenesis and has a broad spectrum of biological activities. This article will review the mechanisms of action of the drug and their relevance to the treatment of myelodysplastic syndrome (MDS), a disease for which no standard treatment currently exists. The early clinical experience has confirmed the activity of arsenic trioxide in MDS. The preliminary results of ongoing Phase II studies conducted in patients with MDS suggest that arsenic trioxide produces haematological improvement including durable transfusion independence in approximately 30% of patients. The current data are presented and discussed in this review.

Myelodysplastic Syndrome

During the past 15 years, important progress has been made in the understanding of the biology and prognosis of myelodysplastic syndrome (MDS). MDS is a clonal disorder characterized by ineffective hematopoiesis, which can lead to either fatal cytopenias or acute myelogenous leukemia (AML). Risk-adapted treatment strategies were established because of the high median age (60-75 years) of the MDS patients and the individual history of the disease (number of cytopenias, cytogenetic changes, transfusion requirements). Allogeneic bone marrow transplantation currently offers the only potentially curative treatment, but this form of therapy is not available for the typical MDS patient, who is >60 years of age. Therapy with erythropoietin and G-CSF has improved the quality of life of selected patients. The development of small molecules directed against specific molecular targets with minimal adverse effects is the hope for the future. Innovative uses of immunomodulatory agents and the optimizing of cytotoxic treatment should continue to help in the treatment of MDS.

High-dose idarubicin and busulphan as conditioning to autologous stem cell transplantation in adult patients with acute myeloid leukaemia

Between 30 and 50% of patients with acute myeloid leukaemia (AML) relapse after autologous stem cell transplantation (ASCT). One possibility of reducing the relapse rate could be the adoption of conditioning regimens specifically designed for AML. We report treatment results achieved with a new conditioning for ASCT, based on high-dose idarubicin (IDA) plus oral busulphan. Patients (n = 40) were conditioned with a regimen consisting of 3 d continuous intravenous infusion IDA at 20 mg/m2, followed by 4 d conventional dose oral busulphan. Unpurged peripheral blood stem cells were used in all cases. All patients had non-M3-AML and were in first complete remission (CR). The median number of CD34+ cells infused was 6.9 x 10(6)/l (2.6-24). No case of transplant-related mortality occurred. In all cases, left ventricular ejection fraction remained unmodified after ASCT. Thirty-three of 40 patients (82%) had grade 3-4 mucositis requiring total parenteral nutrition in all cases. After a median follow up for surviving patients of 32 months from ASCT, 30 patients (75%) are alive and 26 (65%) are in continuous CR. Our data show that a conditioning regimen based on high-dose IDA plus busulphan results in an encouraging reduction of the relapse rate after ASCT in AML.

Therapeutic spectrum in the treatment of myelodysplastic syndromes

During the last 15 years, important progress has been made in the understanding of the biology and prognosis of myelodysplastic syndromes (MDS). It is a clonal disorder, characterised by ineffective haematopoiesis, which can lead to either fatal cytopenias or acute myelogenous leukaemias. Risk-adapted treatment strategies were established, due to the high median age (60 - 75 years) of the MDS patients and the individual history of the disease (i.e. number of cytopenias, cytogenetic changes, transfusion requirements). Allogeneic bone marrow transplantation currently offers the only potentially curative treatment, but this form of therapy is not available for the 'typical' MDS patient, who is > 60 years of age. Therapy with erythropoietin and granulocyte colony-stimulating factor has improved the quality of life of selected patients. The development of target-specific therapies, including antibodies and small molecules directed against specific molecular alterations in MDS, with minimal adverse effects, is the hope for the future. Furthermore, the innovative use of immunomodulatory agents and the optimising of cytotoxic treatment should continue to help in the treatment of MDS.

Myelodysplastic Syndromes

The development of new therapeutic strategies for myelodysplastic syndromes (MDS) has gained new momentum fueled by improved characterization of the disease’s natural history and biology and by the recent US Food and Drug Administration (FDA) approval of the first agent with an indication for MDS. By integrating morphologic and cytogenetic features with greater discriminatory power, the World Health Organization (WHO) has refined the classification of these stem cell malignancies and enhanced its prognostic utility. Recognition that the malignant phenotype, which characterizes MDS, may arise from mechanistically diverse biological processes has raised new awareness that treatment strategies must be tailored to the pathobiology of the disease. Therapeutics targeting chromatin structure, angiogenesis and the microenvironment that nurtures the MDS phenotype have demonstrated remarkable activity and offer an opportunity to alter the natural history of the disease. This chapter provides an overview of recent developments in the characterization of MDS from the microscope to the laboratory and the translation of these findings into promising therapeutics.

In Section I, Dr. James Vardiman reviews the cytogenetic abnormalities that characterize MDS, their clinical and pathologic significance, and the application of the WHO classification. In Section II, Dr. Alan List reviews treatment goals driven by prognostic variables and biological features of the disease that have led to promising small molecule, selective therapeutics. In Section III, Dr. Jean-Pierre Issa provides an overview of epigenetic events regulating gene expression, which may be exploited therapeutically by chromatin remodeling agents. In Section IV, Dr. Theo DeWitte discusses new developments in hematopoietic stem cell transplantation, including reduced-intensity and myeloablative approaches.

No benefit from adding GM-CSF to induction chemotherapy in transforming myelodysplastic syndromes: better outcome in patients with less proliferative disease

In this prospective randomized multicenter trial 93 patients, median age 72 years, with RAEB-t (n=25) and myelodysplastic syndrome (MDS)-AML (n=68) were allocated to a standard induction chemotherapy regimen (TAD 2+7) with or without addition of granulocyte-macrophage-CSF (GM-CSF). The overall complete remission (CR) rate was 43% with no difference between the arms. Median survival times for all patients, CR patients, and non-CR patients were 280, 550, and 100 days, respectively, with no difference between the arms. Response rates were significantly better in patients with serum lactate dehydrogenase (S-LDH) levels </=9.5 microkat/l, bone marrow cellularity </=70%, and WBC counts <4.0 x 10(9)/l, but S-LDH was the only variable independently associated with response by logistic regression analysis. Cox's regression analysis identified four significant prognostic factors for survival: bone marrow cellularity, S-LDH, cytogenetic risk group (International Prognostic Scoring System), and age. Only bone marrow cellularity (P=0.01) and S-LDH (P=0.0003) retained statistical significance in the log-rank test. Severe adverse events were significantly more common in the GM-TAD arm (P=0.01). Thus, addition of GM-CSF to chemotherapy showed no clinical benefit in terms of response but carried an increased risk for side effects. We present a clinically useful tool to predict response to chemotherapy and survival in elderly patients with transforming MDS, favoring patients with features of less proliferative disease.

Hematopoietic stem cell transplantation for hematological malignancies in Europe

Hematopoietic stem cell transplants (HSCTs) are considered the best treatment option for many hematological malignancies, and transplant numbers have increased five-fold during the last decade. Only a few controlled prospective studies are available, and different opinions prevail. Data from 118 167 HSCT (36% allogeneic, 64% autologous) collected within the EBMT activity survey from 1990 to 2001 were used to assess trends over time, transplant rates and coefficient of variation (CV) of transplant rates among European countries for acute myeloid leukemia (AML; 18.5%), acute lymphocytic leukemia (ALL; 12%), chronic myeloid leukemia (CML; 11.5%), myelodysplastic syndromes (MDS; 3%), lymphoproliferative disorders (LPS; 36.3%) and multiple myeloma (MM; 18.7%). Transplant rates increased in all countries and for all indications from 1990 to 2001 from 1.7-fold (CML) to 24.8-fold (MM). Transplant rates have declined for CML since 1999. Autologous HSCT are the preferred choice for LPS and MM, allogeneic HSCT for ALL and myeloid malignancies. CVs of less than 50% suggest consensus for allogeneic HSCT in AML, ALL, CML, MDS and NHL, for autologous HSCT in LPS and MM. These data give an overview of the current status of HSCT for hematological malignancies in Europe and provide objective information for health-care providers and patient counselling.

Acute leukemia: a pediatric perspective

The spectrum of hematological malignancies differs markedly between children and adults. Moreover, diseases such as acute lymphoblastic leukemia, acute myeloid leukemia, and myelodysplastic syndrome also demonstrate distinct biologic features and responses to treatment between these populations. In this review, we summarize our current understanding of the molecular pathology of acute leukemia and myelodysplastic syndrome, emphasizing areas in which studies in pediatric patients are providing unique insights into the hematopoietic malignancies of adults.