The presence of an HLA-identical sibling donor has no impact on outcome of patients with high-risk MDS or secondary AML (sAML) treated with intensive chemotherapy followed by transplantation: results of a prospective study of the EORTC, EBMT, SAKK and GIMEMA Leukemia Groups (EORTC study 06921)

Biologic Assignment Trial of Reduced-Intensity Hematopoietic Cell Transplantation Based on Donor Availability in Patients 50-75 Years of Age With Advanced Myelodysplastic Syndrome

PURPOSE

Allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative therapy for myelodysplastic syndromes (MDS), although it is infrequently offered to older patients. The relative benefits of HCT over non-HCT therapy in older patients with higher-risk MDS have not been defined.

METHODS

We conducted a multicenter biologic assignment trial comparing reduced-intensity HCT to hypomethylating therapy or best supportive care in subjects 50-75 years of age with intermediate-2 or high-risk de novo MDS. The primary outcome was overall survival probability at 3 years. Between January 2014 and November 2018, we enrolled 384 subjects at 34 centers. Subjects were assigned to the Donor or No-Donor arms according to the availability of a matched donor within 90 days of study registration.

RESULTS

The median follow-up time for surviving subjects was 34.2 months (range: 2.3-38 months) in the Donor arm and 26.9 months (range: 2.4-37.2 months) in the No-Donor arm. In an intention-to-treat analysis, the adjusted overall survival rate at 3 years in the Donor arm was 47.9% (95% CI, 41.3 to 54.1) compared with 26.6% (95% CI, 18.4 to 35.6) in the No-Donor arm (P = .0001) with an absolute difference of 21.3% (95% CI, 10.2 to 31.8). Leukemia-free survival at 3 years was greater in the Donor arm (35.8%; 95% CI, 29.8 to 41.8) compared with the No-Donor arm (20.6%; 95% CI, 13.3 to 29.1; P = .003). The survival benefit was seen across all subgroups examined.

CONCLUSION

We observed a significant survival advantage in older subjects with higher-risk MDS who have a matched donor identified and underwent reduced-intensity HCT, when compared with those without a donor. HCT should be included as an integral part of MDS management plans in fit older adults with higher-risk MDS.

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).

Indications for allo- and auto-SCT for haematological diseases, solid tumours and immune disorders: current practice in Europe, 2015

This is the sixth special report that the European Society for Blood and Marrow Transplantation regularly publishes on the current practice and indications for haematopoietic SCT for haematological diseases, solid tumours and immune disorders in Europe. Major changes have occurred in the field of haematopoietic SCT over the last years. Cord blood units as well as haploidentical donors have been increasingly used as stem cell sources for allo-SCT, thus, augmenting the possibility of finding a suitable donor for a patient. Continuous refinement of conditioning strategies has also expanded not only the number of potential indications but also has permitted consideration of older patients or those with co-morbidity for a transplant. There is accumulating evidence of the role of haematopoietic SCT in non-haematological disorders such as autoimmune diseases. On the other hand, the advent of new drugs and very effective targeted therapy has challenged the role of SCT in some instances or at least, modified its position in the treatment armamentarium of a given patient. An updated report with revised tables and operating definitions is presented.

Multicenter biologic assignment trial comparing reduced-intensity allogeneic hematopoietic cell transplant to hypomethylating therapy or best supportive care in patients aged 50 to 75 with intermediate-2 and high-risk myelodysplastic syndrome: Blood and Marrow Transplant Clinical Trials Network #1102 study rationale, design, and methods

The introduction of reduced-intensity conditioning (RIC) regimens made it possible to offer allogeneic hematopoietic cell transplantation (alloHCT) to older patients with myelodysplastic syndromes (MDS). However, the relative risks and benefits of alloHCT compared with novel nontransplant therapies continue to be the source of considerable uncertainty. We will perform a prospective biologic assignment trial to compare RIC alloHCT with nontransplant therapies based on donor availability. Primary outcome is 3-year overall survival. Secondary outcomes include leukemia-free survival, quality of life, and cost-effectiveness. Four hundred patients will be enrolled over roughly 3 years. Planned subgroup analyses will evaluate key biologic questions, such as the impact of age and response to hypomethylating agents on treatment effects. Findings from this study potentially may set a new standard of care for older MDS patients who are considered candidates for alloHCT.

Allogeneic hematopoietic stem cell transplantation for myelodysplastic syndromes

Allogeneic stem cell transplantation (SCT) is the only treatment with curative potential for myelodysplastic syndrome (MDS). The availability of SCT has been expanded with the introduction of reduced intensity conditioning for older patients and the use of alternative donors. Treatment-related mortality and relapse have remained major barriers to uniform success and there is a significant need for innovative approaches to improve these outcomes. Encouraging results have been reported for patients who lack a human leukocyte antigen-identical donor with the use of cord blood and haploidentical donors. Improved approaches for patient selection and optimization of the timing of SCT are needed. New prognostic classification schemas identify risk groups for disease outcomes and facilitate decisions with regard to SCT. Patients with intermediate-2 and high-risk disease and those with therapy-related MDS have a poor prognosis with alternative therapies; improved results have been reported with hematopoietic transplantation. The optimum timing for SCT is controversial in the era of hypomethylating agents. Initial conservative management is indicated for patients with low-risk disease. Hematopoietic transplantation remains the only curative treatment for patients with MDS and should be used before patients overtly progress to advanced disease. Failure to respond to hypomethylating agents does not adversely affect the outcome of SCT; these patients might achieve durable remissions with hematopoietic transplantation. Refined prognostic markers are needed to identify poor prognosis patients to guide patient selection for SCT, and novel transplantation approaches are required to reduce the risk of disease relapse and complications of the procedure.

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.

Allogeneic stem cell transplantation for elderly patients with myelodysplastic syndrome

Allogeneic hematopoietic stem cell transplantation (SCT) is well accepted as a curative treatment approach for younger patients with myelodysplastic syndrome (MDS) and has become one of the most frequent indications for allogeneic SCT as reported to the Center for International Blood and Marrow Transplant Research. However, MDS patients are usually elderly with a median age of approximately 75 years at diagnosis. Large register studies have confirmed the feasibility of the procedure in elderly MDS patients; and in the register of the European Group for Blood and Marrow Transplantation, one-third of the allogeneic transplant procedures for MDS were performed in 2010 in patients older than 60 years. Despite its curative potential, its role in the treatment of elderly MDS patients is less defined. Because of the inherent complications of the transplantation leading to treatment-related mortality and the risk of relapse, a careful calculation of the benefit for each patient is mandatory, taking into account comorbidities, disease status, donor selection, and effective nontransplant therapies. Prospective multicenter studies are needed to define optimal intensity of the conditioning regimen, timing of transplantation within a treatment algorithm, including drug-based therapies, and posttransplant strategies to reduce the risk of relapse.

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.

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.

Hematopoietic stem cell transplantation for MDS

Hematopoietic stem cell transplantation (HSCT) offers potentially curative therapy for patients with myelodysplastic syndromes (MDS). However, as the majority of patients with MDS are in the seventh or eighth decade of life, conventional transplant regimens have been used only infrequently, and only with the development of reduced-intensity conditioning has transplantation been applied more broadly to older patients. Dependent upon disease status at the time of transplantation, 30% to 70% of patients can be expected to be cured of their disease and survive long term. However, posttransplant relapse and graft-versus-host disease (GVHD) remain problems and further investigations are needed.

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.

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.

Use of biological assignment in hematopoietic stem cell transplantation clinical trials

BACKGROUND

When comparing treatments for a specific illness, it is sometimes impractical or impossible to conduct a randomized clinical trial (RCT). Biological assignment trials are one alternative design. In hematopoietic stem cell transplantation (HCT) trials, a human leukocyte antigen (HLA)-matched sibling donor is considered optimal, but such donors are available for only 20-30% of otherwise eligible patients. Rather than randomizing only those with a matched sibling donor, in a recent multiple myeloma trial, the type of HCT each patient received was biologically based, i.e., chosen according to whether or not the patient had a matched sibling donor.

PURPOSE

This article describes the design and implementation of biological assignment trials as well as their advantages and disadvantages.

METHODS

We focus on several aspects of such trials, including efficiency of trial duration, ethical issues, and potential sources of bias. Statistical issues are considered including sample size calculations, monitoring for biased enrollment, and adjustments for imbalances in patient characteristics. A multiple myeloma trial is used as an illustration.

RESULTS

Although they often require a larger sample size, biological assignment trials can provide substantial efficiency in terms of study duration over randomized trials when accrual to a randomized trial would be slow. Determination of sample size requires consideration of the anticipated proportion of patients with a biologically favored (HLA-matched sibling) donor. An add-on randomization of patients without a matched sibling donor may alleviate ethical concerns about applicability of study results to all patients regardless of whether the biological assignment groups differ with respect to outcome.

LIMITATIONS

Prognostic factor imbalance and enrollment bias can occur in a biological assignment trial. Statistical adjustment for potential imbalance in prognostic factors is important, as is monitoring center accrual for enrollment bias and performing an appropriate intention-to-treat analysis.

CONCLUSIONS

A biological assignment trial can be a reasonable way to compare treatments which are biologically based, such as HLA-matched sibling transplants, when the gold-standard randomized trial design is impractical or impossible. Implementing such a trial requires careful consideration of the ethical issues and potential biases.

Fludarabine/intermediate-dose cytarabine with or without allogeneic hematopoietic stem cell transplantation in poor-risk leukemia: a single center experience

Disease recurrence has been and remains the leading cause of treatment failure in patients with high-risk leukemia. We retrospectively analyzed outcome in 61 patients with high-risk leukemia receiving a combination of fludarabine and intermediate-dose cytarabine as induction (n = 11) or salvage therapy (n = 35). Thirty-six patients having a suitable stem cell donor proceeded to allogeneic hematopoietic stem cell transplantation (HSCT). Ten patients received fludarabine-based salvage therapy without consecutive allogeneic transplantation and 15 patients received fludarabine/intermediate-dose cytarabine because of disease relapse following allogeneic stem cell transplantation. In patients without prior allogeneic HSCT (n = 46) the complete remission rate (CR) was 41% with a CR rate of 46 and 14% in patients with acute myeloid leukemia (AML) and with acute lymphoblastic leukemia (ALL), respectively. Overall survival for patients achieving a CR was 41 versus 0% for patients not achieving CR (P < 0.0001). The best outcome was observed in patients receiving an allogeneic HSCT in CR following fludarabine/ intermediate-dose cytarabine (47 vs. 0% for patients not in CR at the time of allografting, P = 0.01). All 10 patients receiving fludarabine/intermediate-dose cytarabine without subsequent allogeneic HSCT died within 3 years either of disease relapse/progression or infection. Only 1/15 (7%) patients receiving fludarabine/intermediate-dose cytarabine because of relapse following allogeneic HSCT became a long-term survivor. By multivariate analysis achieving CR, receiving an allogeneic HSCT, and being in first relapse or untreated were the only parameters that significantly determine the outcome. Although preliminary only high-risk AML patients having a stem cell donor are candidates for fludarabine/intermediate-dose cytarabine and only those achieving a CR should be referred to subsequent allogeneic HSCT. All other patients with high-risk leukemia are candidates for experimental therapies within controlled trials.

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.

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.

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.

A Long-term Follow-up Analysis in Adult Acute Myeloid Leukemia Patients after Hematopoietic Stem Cell Transplantation

Aims and Background

Over the last 17 years, 119 adult acute myeloid leukemia patients have undergone hematopoietic stem cell transplantation at our Center.

Study Design

Seventy patients in first complete remission received hematopoietic stem cell transplantation (28 allogeneic and 42 autologous HSCT) as late intensification after conventional chemotherapy; 38 patients received allogeneic hematopoietic stem cell transplantation in a more advanced phase. A reference group was built up by collecting 40 acute myeloid leukemia patients who received high-dose cytosine arabinoside as late intensification and whose complete remission lasted more than 10 months.

Results

Results of the study led to conclude that an earlier timing of allogeneic hematopoietic stem cell transplantation can be recommended in order to treat patients who would otherwise suffer an early relapse.

Conclusions

The outcome of autologous hematopoietic stem cell transplantation in patients not in first complete remission supports the possibility of achieving good quality second complete remissions and suggests that autografting may be a life-saving strategy in selected acute myeloid leukemia patients with advanced disease.

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.

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.