Antithymocyte globulin (ATG)-based therapy in patients with myelodysplastic syndromes

Response to Hypomethylating Agents in Myelodysplastic Syndrome Is Associated With Emergence of Novel TCR Clonotypes

Aberrant T-cell function is implicated in the pathogenesis of myelodysplastic syndrome (MDS). Monitoring the T-cell receptor (TCR) repertoire can provide insights into T-cell adaptive immunity. Previous studies found skewed TCR repertoires in MDS compared to healthy patients; however these studies that leverage mRNA-based spectratyping have limitations. Furthermore, evaluating the TCR repertoire in context of hypomethylating agents (HMAs) treatment can provide insights into the dynamics of T-cell mediated responses in MDS. We conducted immunosequencing of the CDR3 regions of TCRβ chains in bone marrows of 11 MDS patients prior to treatment (n=11 bone marrows prior to treatment), and in at least 2 timepoints for each patient following treatment (n=26 bone marrow aspirates post-treatment) with (HMA), alongside analyzing bone marrows from 4 healthy donors as controls. TCR repertoires in MDS patients were more clonal and less diverse than healthy donors. However, unlike previous reports, we did not observe significant skewness in CDR3 length or spectratyping. The global metrics of TCR profiling including richness, clonality, overlaps were not significantly changed in responders or non-responders following treatment with HMAs. However, we found an emergence of novel clonotypes in MDS patients who responded to treatment, while non-responders had a higher frequency of contracted clonotypes following treatment. By applying GLIPH2 for antigen prediction, we found rare TCR specificity clusters shared by TCR clonotypes from different patients at pre- or following treatment. Our data show clear differences in TCR repertoires of MDS compared with healthy patients and that novel TCR clonotype emergence in response to HMA therapy was correlated with response. This suggests that response to HMA therapy may be partially driven by T-cell mediated immunity and that the immune-based therapies, which target the adaptive immune system, may play a significant role in select patients with MDS.

Hypoplastic Myelodysplastic Syndromes: Just an Overlap Syndrome?

Simple Summary

Hypoplastic myelodysplastic syndromes (hMDS) represent a diagnostic conundrum. They share morphologic and clinical features of both MDS (dysplasia, genetic lesions and cytopenias) and aplastic anemia (AA; i.e., hypocellularity and autoimmunity) and are not comprised in the last WHO classification. In this review we recapitulate the main clinical, pathogenic and therapeutic aspects of hypo-MDS and discuss why they deserve to be distinguished from normo/hypercellular MDS and AA. We conclude that hMDS may present in two phenotypes: one more proinflammatory and autoimmune, more similar to AA, responding to immunosuppression; and one MDS-like dominated by genetic lesions, suppression of immune surveillance, and tumor escape, more prone to leukemic evolution.

Abstract

Myelodysplasias with hypocellular bone marrow (hMDS) represent about 10–15% of MDS and are defined by reduced bone marrow cellularity (i.e., <25% or an inappropriately reduced cellularity for their age in young patients). Their diagnosis is still an object of debate and has not been clearly established in the recent WHO classification. Clinical and morphological overlaps with both normo/hypercellular MDS and aplastic anemia include cytopenias, the presence of marrow hypocellularity and dysplasia, and cytogenetic and molecular alterations. Activation of the immune system against the hematopoietic precursors, typical of aplastic anemia, is reckoned even in hMDS and may account for the response to immunosuppressive treatment. Finally, the hMDS outcome seems more favorable than that of normo/hypercellular MDS patients. In this review, we analyze the available literature on hMDS, focusing on clinical, immunological, and molecular features. We show that hMDS pathogenesis and clinical presentation are peculiar, albeit in-between aplastic anemia (AA) and normo/hypercellular MDS. Two different hMDS phenotypes may be encountered: one featured by inflammation and immune activation, with increased cytotoxic T cells, increased T and B regulatory cells, and better response to immunosuppression; and the other, resembling MDS, where T and B regulatory/suppressor cells prevail, leading to genetic clonal selection and an increased risk of leukemic evolution. The identification of the prevailing hMDS phenotype might assist treatment choice, inform prognosis, and suggest personalized monitoring.

Use of immunosuppressive therapy for management of myelodysplastic syndromes: a systematic review and meta-analysis

Immunosuppressive therapy (IST) is one therapy option for treatment of patients with lower-risk myelodysplastic syndromes (MDS). However, the use of several different immunosuppressive regimens, the lack of high-quality studies, and the absence of validated predictive biomarkers pose important challenges. We conducted a systematic review and meta-analysis according to the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines and searched MEDLINE via PubMed, Ovid EMBASE, COCHRANE registry of clinical trials (CENTRAL), and the Web of Science without language restriction from inception through September 2018, as well as relevant conference proceedings and abstracts, for prospective cohort studies or clinical trials investigating IST in MDS. Fixed and Random-effects models were used to pool response rates. We identified nine prospective cohort studies and 13 clinical trials with a total of 570 patients. Overall response rate was 42.5% [95% confidence interval (CI): 36.1-49.2%] including a complete remission rate of 12.5% (95%CI: 9.3-16.6%) and red blood cell transfusion independence rate of 33.4% (95% CI: 25.1-42.9%). The most commonly used forms of IST were anti-thymocyte globulin alone or in combination with cyclosporin A with a trend towards higher response rates with combination therapy. Progression rate to acute myeloid leukemia was 8.6% per patient year (95%CI: 3.3-13.9%). Overall survival and adverse events were only inconsistently reported. We were unable to validate any biomarkers predictive of a therapeutic response to IST. IST for treatment of lower-risk MDS patients can be successful to alleviate transfusion burden and associated sequelae.

The use of immunosuppressive therapy in MDS: clinical outcomes and their predictors in a large international patient cohort

Most studies of immunosuppressive therapy (IST) in myelodysplastic syndromes (MDS) are limited by small numbers and their single-center nature, and report conflicting data regarding predictors for response to IST. We examined outcomes associated with IST and predictors of benefit in a large international cohort of patients with MDS. Data were collected from 15 centers in the United States and Europe. Responses, including red blood cell (RBC) transfusion independence (TI), were assessed based on the 2006 MDS International Working Group criteria, and overall survival (OS) was estimated by Kaplan-Meier methods. Logistic regression models estimated odds for response and TI, and Cox Proportional Hazard models estimated hazards ratios for OS. We identified 207 patients with MDS receiving IST, excluding steroid monotherapy. The most common IST regimen was anti-thymocyte globulin (ATG) plus prednisone (43%). Overall response rate (ORR) was 48.8%, including 11.2% (95% confidence interval [CI], 6.5%-18.4%) who achieved a complete remission and 30% (95% CI, 22.3%-39.5%) who achieved RBC TI. Median OS was 47.4 months (95% CI, 37-72.3 months) and was longer for patients who achieved a response or TI. Achievement of RBC TI was associated with a hypocellular bone marrow (cellularity < 20%); horse ATG plus cyclosporine was more effective than rabbit ATG or ATG without cyclosporine. Age, transfusion dependence, presence of paroxysmal nocturnal hemoglobinuria or large granular lymphocyte clones, and HLA DR15 positivity did not predict response to IST. IST leads to objective responses in nearly half the selected patients with the highest rate of RBC TI achieved in patients with hypocellular bone marrows.

Cyclosporine Combined with Levamisole for Lower-Risk Myelodysplastic Syndromes

Clinical and experimental evidence suggests an immune-mediated pathophysiology in subjects with lower-risk myelodysplastic syndromes (MDS) in whom immunosuppressive therapy may be effective. The novel immunosuppressive strategy of cyclosporine A (CsA) alternately combined with levamisole (LMS; CsA + LMS regimen) can dramatically improve the response rate and survival in aplastic anemia from those of our previous study. Herein, we retrospectively analyzed the data of 89 lower-risk MDS patients who received the CsA + LMS regimen. A total of 63 patients (70.8%) achieved either complete remission or hematological improvement at 4 months. Overall, 51, 41 and 19 patients had erythroid, platelet and neutrophil responses, respectively. Following the CsA + LMS regimen, 6 patients progressed to more advanced MDS at a median interval of 5 months (range, 3-42 months). The estimated 24-month progression-free survival was 82.2% (95% CI, 72.84-91.56) for all patients. Within the median follow-up of 18.5 months (range, 7.0-61.0), 6 patients died. In conclusion, the CsA + LMS regimen alleviated cytopenias and improved survival and freedom from evolution, suggesting that it could be reserved as an alternative choice for lower-risk MDS.

T-cell receptor Vβ skewing frequently occurs in refractory cytopenia of childhood and is associated with an expansion of effector cytotoxic T cells: a prospective study by EWOG-MDS

Immunosuppressive therapy (IST), consisting of antithymocyte globulin and cyclosporine A, is effective in refractory cytopenia of childhood (RCC), suggesting that, similar to low-grade myelodysplastic syndromes in adult patients, T lymphocytes are involved in suppressing hematopoiesis in a subset of RCC patients. However, the potential role of a T-cell-mediated pathophysiology in RCC remains poorly explored. In a cohort of 92 RCC patients, we prospectively assessed the frequency of T-cell receptor (TCR) β-chain variable (Vβ) domain skewing in bone marrow and peripheral blood by heteroduplex PCR, and analyzed T-cell subsets in peripheral blood by flow cytometry. TCRVβ skewing was present in 40% of RCC patients. TCRVβ skewing did not correlate with bone marrow cellularity, karyotype, transfusion history, HLA-DR15 or the presence of a PNH clone. In 28 patients treated with IST, TCRVβ skewing was not clearly related with treatment response. However, TCRVβ skewing did correlate with a disturbed CD4(+)/CD8(+) T-cell ratio, a reduction in naive CD8(+) T cells, an expansion of effector CD8(+) T cells and an increase in activated CD8(+) T cells (defined as HLA-DR(+), CD57(+) or CD56(+)). These data suggest that T lymphocytes contribute to RCC pathogenesis in a proportion of patients, and provide a rationale for treatment with IST in selected patients with RCC.

Long-term outcome of immunosuppressive therapy for Japanese patients with lower-risk myelodysplastic syndromes

To investigate the long-term usefulness of immunosuppressive therapy (IST) for Japanese patients with lower-risk myelodysplastic syndromes, we retrospectively analyzed 29 MDS patients who were treated with cyclosporine A alone or with anti-thymocyte globulin at a single institute in Japan. A total of 58.6 % of patients showed hematological response to IST. Overall survival of all patients was 74.5 % at 5 years and 48.3 % at 10 years. The major adverse event was the elevation of creatinine level (grade 1 and 2). Eleven patients were still on IST at the time of analysis with, at least, some clinical benefits. Pneumonia was the most frequent cause of death (eight of 12 deaths), followed by bleeding (three of 12); most of the patients who died were non-responders. The presence of paroxysmal nocturnal hemoglobinuria-type cells was significantly associated with both response to IST and long-term survival by univariate analysis. The 10-year overall survival of responders (72.2 %) was significantly superior to that of non-responders (15.6 %, P < 0.0001). These results suggest that IST using cyclosporine A provides long-term benefit for Japanese patients with lower-risk MDS.

Therapy-related myeloid neoplasms after autologous hematopoietic stem cell transplantation in lymphoma patients

Lymphoma patients treated with autologous transplantation (ASCT) live an increasingly long life with the recent advancement in therapeutic modalities. This has resulted in an increase in the incidence of therapy-related myeloid neoplasms (t-MN), which is one of the leading causes of non-relapse mortality. Several observational studies have linked the development of t-MN after ASCT with the intensity and frequency of chemotherapy, particularly alkylating agents, use of total body irradiation (TBI), and peripheral blood progenitor cells. In addition, role of genetic factors is increasingly being identified. It is postulated that the use of chemotherapy prior to ASCT results in DNA damage of progenitor cells, mitochondrial dysfunction, and altered gene expression related to DNA repair, metabolism as well as hematopoietic regulation. Cytogenetic studies have shown the presence of abnormalities in the peripheral blood progenitor cells prior to ASCT. It is, therefore, likely that the reinfusion of peripheral blood progenitor cells, proliferative stress on infused progenitor cells during hematopoietic regeneration and associated telomere shortening ultimately result in clonal hematopoiesis and blastic transformation. Cytopenias, myelodysplasia, or cytogenetic abnormalities are common and can be transient after ASCT; therefore, only when present together, they do confirm the diagnosis of t-MN. Attempts to reduce the occurrence of t-MN should be directed toward minimizing the exposure to the identified risk factors. Although the median survival is few months to less than a year, studies have shown the promising role of allogeneic transplantation in select young t-MN patients without high-risk cytogenetics. In this review we will explain the recent findings in the field of t-MN in lymphoma patients that have implications for identifying the molecular and genetic mechanisms of leukemogenesis and discuss potential strategies to reduce the risk of t-MN in this patient population.

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.

Immunomodulatory treatment of myelodysplastic syndromes: antithymocyte globulin, cyclosporine, and alemtuzumab

It is now well accepted that a subgroup of patients with myelodysplastic syndromes (MDS) can recover from pancytopenia following immunosuppressive treatment (IST). For many years immunosuppression with antilymphocyte antibodies has been a standard treatment approach for patients with severe aplastic anemia (SAA). The initial concept of using immunosuppression to treat pancytopenic patients with MDS was based on the premise that MDS might share with SAA an autoimmune basis for the bone marrow failure common to both conditions. The idea was supported by reports of favorable outcomes in occasional cases of MDS treated with antithymocyte globulin (ATG). Today, various forms of IST have been successfully used to restore hematopoiesis in MDS in many centers worldwide. In this review we outline the rationale for use of IST in MDS, and describe studies which help to define the patients with MDS likely to respond to IST. We summarize 18 published clinical trials using IST for MDS and discuss how these studies have helped to define the MDS subgroups likely to respond to treatment, the nature and durability of the response, the impact of IST on long-term outcome, and the best treatment approach.

Dendritic cells in myelodysplastic syndromes: from pathogenesis to immunotherapy

Myelodysplastic syndromes (MDS) are clonal disorders of the hematopoietic stem cell characterized by ineffective hematopoiesis leading to peripheral cytopenias. Different processes are involved in its pathogenesis, such as (epi)genetic alterations and immunological dysfunctions. The nature of immune dysregulation is markedly different between various MDS risk groups. In low-risk MDS, the immune system is in a proinflammatory state, whereas in high-risk disease, immunosuppressive features facilitate expansion of the dysplastic clone and can eventually lead to disease progression to acute myeloid leukemia. Various cell types contribute to dysregulation of immune responses in MDS. Dendritic cells (DCs) are important regulators of immunity. However, the role of DCs in MDS has yet to be elucidated. It has been suggested that impaired DC function can hamper adequate immune responses. This review focuses on the involvement of DCs in immune dysregulation in low- and high-risk MDS and the implications for DC-targeted therapies.

How we treat lower-risk myelodysplastic syndromes

Lower-risk myelodysplastic syndromes (MDSs) are defined as having low or intermediate 1 risk by the International Prognostic Scoring System and are characterized mainly by anemia in most cases. Supportive care--primarily red blood cell transfusions--remains an important component of their treatment, but exposes patients to insufficient correction of anemia, alloimmunization, and organ iron overload (for which the role of iron chelation remains debated). Treatment aimed at preventing anemia recurrence should therefore be used whenever possible. Erythropoiesis stimulating agents remain the first-line treatment of anemia in most lower-risk MDS without del(5q), whereas anemia of low-risk MDS with del 5q responds to lenalidomide in two-thirds of the cases, but this drug should be used cautiously because profound cytopenias may occur initially. Treatment after failure of those first-line therapies are disappointing overall, with many patients eventually requiring long-term transfusions, but encouraging results have been reported with hypomethylating agents and lenalidomide. Selected patients respond to antithymocyte globulins, and thrombopoietin receptor agonists are under investigation in lower-risk MDS with thrombocytopenia. Some patients, while remaining at a "lower risk" MDS level, have severe cytopenias and/or poor prognostic factors, found using newer prognostic parameters, or resistance to treatment, making them urgent candidates for more intensive approaches, including allogeneic stem cell transplantation.

Emerging immunosuppressive drugs in myelodysplastic syndromes

INTRODUCTION

Myelodysplastic syndromes (MDS) are characterized by dysplastic morphologic features and ineffective hematopoiesis. Pathophysiological characteristics change over time making therapeutic development a major challenge. In early MDS, cytopenias arise or are exacerbated by humoral and cellular immune-mediators that suppress hematopoietic progenitor survival and alter the bone marrow microenvironment.

AREAS COVERED

In this review, current immunosuppressive regimens are described. To identify new therapies that may enhance immunosuppressive therapy (IST) response and identify pharmacodynamic biomarkers for patient selection, the inflammasome, cytokines, metabolic pathways and signaling events are described.

EXPERT OPINION

Agents with the potential to induce early, durable hematologic remissions are needed and many new immunosuppressive agents are available for investigation. An immune-mediated mechanism is likely to contribute to MDS early after diagnosis. New approaches that interfere with inflammatory pathways in the bone marrow microenvironment may move closer toward sustained disease control in MDS.

Immune dysregulation in myelodysplastic syndrome

Myelodysplastic syndrome (MDS) represents one of the most challenging health-related problems in the elderly. Characterized by dysplastic morphology in the bone marrow in association with ineffective hematopoiesis, pathophysiological causes of this disease are diverse including genetic abnormalities within myeloid progenitors, altered epigenetics, and changes in the bone marrow microenvironment. The concept that T-cell mediated autoimmunity contributes to bone marrow failure has been widely accepted due to hematologic improvement after immunosuppressive therapy (IST) in a subset of patients. Currently, IST for MDS primarily involves anti-thymocyte globulin (ATG)-based regimens in which responsiveness is strongly associated with younger (under 60 years) age at disease onset. In such cases, progressive cytopenia may occur as a consequence of expanded self-reactive CD8⁺ cytotoxic T lymphocytes (CTLs) that suppress hematopoietic progenitors. Although most hematologists agree that IST can offer durable hematologic remission in younger patients with MDS, an international clinical study and a better understanding of the molecular mechanisms contributing to the expansion of self-reactive CTLs is crucial. In this review, data accumulated in the US, Europe, and Asia will be summarized to provide insight and direction for a multi-center international trial.

Final results of the phase II study of rabbit anti-thymocyte globulin, ciclosporin, methylprednisone, and granulocyte colony-stimulating factor in patients with aplastic anaemia and myelodysplastic syndrome

This report describes the final results of a Phase II clinical trial investigating the efficacy of rabbit antithymocyte globulin (rATG), ciclosporin, steroids, and granulocyte colony-stimulating factor (GCSF) in patients with untreated aplastic anaemia (AA), or low to intermediate-risk and hypocellular myelodysplastic syndrome (MDS). We treated 24 patients each with AA and MDS with rATG (3·5 mg/kg/d × 5; reduced to 2·5 mg/kg/d × 5 in patients with MDS ≥ 55 years), ciclosporin (5 mg/kg orally daily × 6 months), steroids (1 mg/kg daily, tapered off over 1 month), and GCSF. The overall response rate in AA patients was 64% compared to 25% in MDS patients. The median time to response was 3 months in AA patients and 4 months in MDS patients. Pretreatment clinical characteristics, such as age, sex, blood counts, cellularity, cytogenetics, or HLA-DR15 status, did not predict for response. Response to therapy, however, predicted for improved overall survival (OS), with a 3-year OS of 89% vs. 43% in responders versus non-responders, respectively (P < 0·001). Infusion reactions occurred in about half the patients and were manageable. Myelosuppression, elevation in liver enzymes, and infections were common. The early mortality in MDS patients was 13% vs. 0% in AA patients.

Predicting survival of patients with hypocellular myelodysplastic syndrome: development of a disease-specific prognostic score system

BACKGROUND

Although most patients with myelodysplastic syndrome (MDS) exhibit bone marrow hypercellularity, a subset of them present with a hypocellular bone marrow. Specific factors associated with poor prognosis have not been investigated in patients with hypocellular MDS.

METHODS

The authors studied a cohort of 253 patients with hypocellular MDS diagnosed at The University of Texas MD Anderson Cancer Center between 1993 and 2007 and a cohort of 1725 patients with hyper-/normocellular MDS diagnosed during the same time period.

RESULTS

Patients with hypocellular MDS presented more frequently with thrombocytopenia (P < .019), neutropenia (P < .001), low serum β-2 microglobulin (P < .001), increased transfusion dependency (P < .001), and intermediate-2/high-risk disease (57% vs 42%, P = .02) compared with patients with hyper-/normocellular MDS. However, no difference in overall survival was observed between the 2 groups (P = .28). Multivariate analysis identified poor performance status (Eastern Cooperative Oncology Group ≥2), low hemoglobin (<10 g/dL), unfavorable cytogenetics (-7/7q or complex), increased bone marrow blasts (≥5%), and high serum lactate dehydrogenase (>600 IU/L) as adverse independent factors for survival.

CONCLUSIONS

A new prognostic model based on these factors was built that segregated patients into 3 distinct risk categories independent of International Prognostic Scoring System (IPSS) score. This model is independent from the IPSS, further refines IPSS-based prognostication, and may be used to develop of risk-adapted therapeutic approaches for patients with hypocellular MDS.

Immunologic aspects of hypoplastic myelodysplastic syndrome

The pathophysiology of myelodysplastic syndromes (MDS) is multiple, complex, and poorly understood. In some cases of MDS, especially those in which the bone marrow is hypocellular, there is increasing experimental and clinical indication that an immune-mediated damage to hematopoietic precursors and changes in the hematopoiesis-supporting microenvironment contribute to disease development. Increased serum levels of type-1 cytokines, tumor necrosis factor-α (TNF-α), and interferon-γ (INF-γ), and oligoclonal expansion of cytotoxic T cells are observed in human MDS. In some cases, the immunologic attack to the marrow appears to be triggered by MDS-specific antigens, damaging the microenvironment and inducing cell apoptosis especially of normal progenitors. In murine models, dysregulation of osteoprogenitors leads to disrupted hematopoiesis of healthy hematopoietic progenitor and stem cells, eventually resulting in MDS and leukemia. In hypocellular MDS, marrow failure appears to be not only the result of ineffective erythropoiesis of abnormal clones, but also due to inhibition of normal progenitors. Immunosuppressive therapy with cyclosporine, anti-thymocyte globulin, or alemtuzumab may alleviate cytopenias and in some instances induce cytogenetic remission. However, not all patients respond to immunosuppression, and the identification of relevant biomarkers for an immune mechanism is necessary to identify those patients who may benefit from this treatment modality.

Failure of hypomethylating agent-based therapy in myelodysplastic syndromes

Hypomethylating agents such as 5-azacytidine or decitabine have been a major breakthrough in the treatment of patients with myelodysplastic syndromes (MDS). They have been shown to improve transfusion requirements and to change the natural history of the disease. However, with increasing cumulative clinical experience, it has become apparent that these agents are not curative and have their own shortcomings. There is a subgroup of patients who do not respond to frontline therapy and a large, growing cohort of patients that lose response or progress while on hypomethylating agent-based therapy. There are no standard treatment options in this arena and it is therefore a focus of significant research interest. Since the mechanisms of resistance to hypomethylating agents are not known, selection of therapy is largely empiric but must take into account the age, comorbidities, and performance status of the patient, as well as the characteristics of the disease at the time of treatment failure. Higher intensity approaches and allogeneic stem cell transplant can yield improved response rates and long-term disease control but should be limited to a selected cohort of patients who can tolerate the treatment-related morbidities. For the majority of patients who likely will be better candidates for lower intensity therapy, several novel, investigational approaches are becoming available. Among these are newer nucleoside analogues, inhibitors of protein tyrosine kinases, molecules that interact with redox signaling within the cell, immunotherapy approaches, and others. Patients with MDS whose disease has failed to respond to hypomethylating agent therapy should be referred for clinical trials when available. As we learn more about the patterns and mechanisms of failure, the next challenge will be to determine which therapies are suitable for each individual patient.

Efficacy of rabbit anti-thymocyte globulin in severe aplastic anemia

BACKGROUND

A combination of horse anti-thymocyte globulin and cyclosporine produces responses in 60-70% of patients with severe aplastic anemia. We performed a phase II study of rabbit anti-thymocyte globulin and cyclosporine as first-line therapy for severe aplastic anemia.

DESIGN AND METHODS

Twenty patients with severe aplastic anemia treated with rabbit anti-thymocyte globulin were compared to 67 historical control cases with matched clinical characteristics treated with horse anti-thymocyte globulin.

RESULTS

Response rates at 3, 6 and 12 months were similar for patients treated with rabbit anti-thymocyte globulin or horse anti-thymocyte globulin: 40% versus 55% (P=0.43), 45% versus 58% (P=0.44) and 50% versus 58% (P=0.61), respectively. No differences in early mortality rates or overall survival were observed. We then performed multivariable analyses of response at 6 months and overall survival and identified the presence of a paroxysmal nocturnal hemoglobinuria clone (P=0.01) and a pretreatment absolute reticulocyte count greater than 30×10(9)/L (P=0.007) as independent predictors of response and younger age (P=0.003), higher pretreatment absolute neutrophil (P=0.02) and absolute lymphocyte counts (P=0.03) as independent predictors of overall survival. None of the immunogenetic polymorphisms studied was predictive of response to immunosupressive therapy.

CONCLUSIONS

Despite reports suggesting differences in biological activity of different anti-thymocyte globulin preparations, rabbit and horse anti-thymocyte globulin appear to have a similar efficacy for up-front treatment of severe aplastic anemia. Clinicaltrial.gov: NCT01231841).

Immunosuppressive Therapy for Patients With Myelodysplastic Syndrome: A Prospective Randomized Multicenter Phase III Trial Comparing Antithymocyte Globulin Plus Cyclosporine With Best Supportive Care—SAKK 33/99

Purpose

Immunosuppressive treatment is reported to improve cytopenia in some patients with myelodysplastic syndrome (MDS). Combined antithymocyte globulin (ATG) and cyclosporine (CSA) is most effective in patients with immune-mediated marrow failure.

Patients and Methods

This trial was designed to assess the impact of immunosuppression on hematopoiesis, transfusion requirements, transformation, and survival in patients with MDS randomly assigned to 15 mg/kg of horse ATG for 5 days and oral CSA for 180 days (ATG+CSA) or best supportive care (BSC), stratified by treatment center and International Prognostic Scoring System (IPSS) risk score. Primary end point was best hematologic response at 6 months. Eligible patients had an Eastern Cooperative Oncology Group performance status of ≤ 2 and transfusion dependency of less than 2 years in duration.

Results

Between 2000 and 2006, 45 patients received ATG+CSA (median age, 62 years; range, 23 to 75 years; 56% men) and 43 patients received BSC (median age, 65 years; range, 24 to 76 years; 81% men). IPSS score was low, intermediate-1, intermediate-2, high, and not evaluable in eight, 24, seven, one, and five patients on ATG+CSA, respectively, and eight, 25, five, zero, and five patients on BSC, respectively. Refractory anemia, refractory anemia with ringed sideroblasts, refractory anemia with excess of blasts (RAEB) -I, RAEB-II, and hypoplastic disease were present in 21, six, nine, zero, and nine patients on ATG+CSA, respectively, and 18, eight, 11, two, and four patients on BSC, respectively. By month 6, 13 of 45 patients on ATG+CSA had a hematologic response compared with four of 43 patients on BSC (P = .0156). Two-year transformation-free survival (TFS) rates were 46% (95% CI, 28% to 62%) and 55% (95% CI, 34% to 70%) for ATG+CSA and BSC patients, respectively (P = .730), whereas overall survival (OS) estimates were 49% (95% CI, 31% to 66%) and 63% (95% CI, 42% to 78%), respectively (P = .828).

Conclusion

This open-label randomized phase III trial demonstrates that ATG+CSA treatment seems to be associated with hematologic response in a subset of patients without apparent impact on TFS and OS.

Immunosuppressive therapy for myelodysplastic syndromes: refining the indications

Myelodysplastic syndromes (MDS) are often associated with autoimmune processes that contribute to the cytopenias that characterize this disease group. Ten years ago, several investigators described improvement in the cytopenia of MDS following immunosuppressive treatments (IST) with antithymocyte globulin or cyclosporine. These findings have since been widely confirmed. The consensus is that about 30% of unselected transfusion-dependent patients with MDS given IST have sustained hematologic responses and can regain transfusion independence. Over the past decade, prognostic features have been defined that accurately identify the subset of patients most likely to benefit from IST. With increasing knowledge about the pathophysiology of myelosuppression in MDS, we are beginning to define the immunosuppressive agents and schedules with the greatest chance of causing hematologic improvement. Significantly, long-term follow-up indicates that IST responders have a better progression-free survival than comparable patients with MDS who do not receive IST.

Possible role of engraftment syndrome and autologous graft-versus-host disease in myelodysplastic syndrome after autologous stem cell transplantations: retrospective analysis and review of the literature

BACKGROUND

We report a retrospective study of 452 patients with lymphoma from 1991 to 2006, with 274 men and 178 women, median age of 50 years (range, 16-76 years).

PATIENTS AND METHODS

There were 85 patients with Hodgkin lymphoma (HL) and 367 with non-Hodgkin lymphoma (NHL). Eleven patients received a second autologous transplantation for progressive lymphoma, and another 4 received a second allogeneic transplantation for myelodysplastic syndrome (MDS). Twenty-seven patients had skin biopsies, and 2 patients had gastrointestinal biopsies consistent with graft-versus-host disease (GVHD), and 11 patients developed severe engraftment syndrome (ES), as defined by noninfectious fever and skin rash with or without pulmonary infiltrates requiring systemic steroids.

RESULTS

The median follow-up of the patients was 6.2 years, and median overall survival was 5.3 years. Twenty-four patients (5.3%) developed MDS with median time of onset of 4.2 years (range, 8 months to 7.5 years). An additional 5 patients developed clonal karyotypic abnormalities in the bone marrow without clinical MDS. Actuarial probabilities of developing MDS at 5 and 8 years after transplantation were 5% and 15%, respectively.

CONCLUSION

The incidences of MDS are similar in HL and NHL. Multivariate analysis revealed older age, occurrence of ES/GVHD, and longer intervals between the initial diagnoses to transplantation as independent factors. It is conceivable that perturbation to the host immunity caused by either previous chemotherapy or conditioning regimens in the elderly might play a role in the development of MDS after autologous transplantation.

Mouse models of myelodysplastic syndromes

Three general approaches have been used to model myelodysplastic syndrome (MDS) in mice, including treatment with mutagens or carcinogens, xenotransplantation of human MDS cells, and genetic engineering of mouse hematopoietic cells. This article discusses the phenotypes observed in available mouse models for MDS with a concentration on a model that leads to aberrant expression of conserved homeobox genes that are important regulators of normal hematopoiesis. Using these models of MDS should allow a more complete understanding of the disease process and provide a platform for preclinical testing of therapeutic approaches.

Hypoplastic myelodysplastic syndrome (h-MDS) is a distinctive clinical entity with poorer prognosis and frequent karyotypic and FISH abnormalities compared to aplastic anemia (AA)

The aims of the present study are two-fold: (1) to define the clinical features of hypoplastic myelodysplastic syndrome (h-MDS) in comparison with aplastic anemia (AA) and (2) to evaluate the prognostic roles of karyotyping and fluorescent in situ hybridization (FISH) in these hypoplastic marrow syndromes. Based on a medical record review at Seoul National University Hospital, the records of 409 patients diagnosed with either h-MDS or AA were evaluated. Of these patients, 358 had been diagnosed with AA and 51 with h-MDS (median age, 39 years). At diagnosis, 235 and 165 patients underwent karyotyping and FISH analysis, respectively. Karyotypic abnormalities and trisomy 8 and trisomy 1q FISH abnormalities were found more frequently in h-MDS patients than in AA patients. Median overall survival (OS) of h-MDS patients was shorter than that of AA patients (83 vs. 201 months, P=0.007), with the OS of h-MDS patients falling between that of severe and very severe AA patients. Patients with h-MDS had more frequent leukemic conversion (P<0.001) than did AA patients. In AA patients, karyotypic abnormality was not prognostic (P=0.646), while in h-MDS patients, abnormalities in trisomy 1q FISH (P=0.002) and in 20q deletion FISH (P=0.005) were predictive of poor prognosis. In conclusion, the prognosis for h-MDS patients falls between that of severe and very severe AA patients. Moreover, h-MDS is frequently accompanied by karyotypic and FISH abnormalities and is prone to leukemic conversion. Trisomy 1q and 20q deletion FISH abnormalities may have important prognostic roles in patients with h-MDS.

Immunosuppression for myelodysplastic syndrome: how bench to bedside to bench research led to success

Laboratory evidence and clinical evidence suggest that some patients with myelodysplastic syndrome (MDS) have immunologically mediated disease. This article describes the laboratory evidence supporting a role for the immune system in the marrow failure of MDS and clinical trials using IST in these patients.

Anti-thymocyte globulin plus etanercept as therapy for myelodysplastic syndromes (MDS): a phase II study

Immunosuppressive therapies have proven valuable in treating patients with myelodysplastic syndromes (MDS). We evaluated the combination of equine anti-thymocyte globulin (ATGAM) and the soluble tumour necrosis factor receptor, etanercept (Enbrel), in a phase II trial. Twenty-five patients with MDS [4-refractory anaemia (RA), 2-RA with ring sideroblasts, 15-refractory cytopenia with multilineage dysplasia (RCMD), 3-RCMD and ring sideroblasts, 1-RA with excess blasts type 1] in International Prognostic Staging System risk groups low (n = 11) or intermediate-1 (n = 14) were enrolled. All patients were platelet or red cell transfusion-dependent. Nineteen patients completed therapy with ATG at 40 mg/kg per day for four consecutive days, followed by etanercept, 25 mg subcutaneous twice a week for 2 weeks, every month for 4 months. Thirteen patients had haematological improvement (HI)-erythroid, 2 HI-neutrophil, and 6 HI-platelet. One patient with a co-existing diagnosis of multiple sclerosis and rheumatoid arthritis had a complete remission. The overall response by intent to treat analysis among the 25 patients was 56% (95% confidence interval 35-56%). Four patients did not complete their first course of therapy and one patient did not survive to the 8-week post-treatment assessment. Among patients who completed treatment and survived to the 8-week assessment, 70% had at least haematological responses lasting for at least 5 to more than 36 months. Thus, combination therapy with ATG and etanercept was active and safe in patients with MDS.

Abnormalities of the alphabeta T-cell receptor repertoire in advanced myelodysplastic syndrome

OBJECTIVE

Analysis of the alphabeta T-cell receptor (TCR) repertoire in patients with myelodysplastic syndrome (MDS) using the technique of TCR beta-chain spectratyping has provided valuable insight into the pathophysiology of cytopenias in a subset of patients with this heterogeneous disorder. TCR beta-chain spectratypes are complex data sets, however, and statistical tools for their comprehensive analysis are limited. The objective of the present work was to develop a method to enable quantitative evaluation and global comparison of spectratype data from different individuals and to study the prevalence of TCR beta repertoire abnormalities in MDS patients.

MATERIALS AND METHODS

We developed a robust statistical method based on k-means clustering analysis, and applied this method to analysis of the alphabeta TCR repertoires in 50 MDS patients and 23 age-matched healthy controls.

RESULTS

Cluster analysis identified a subset of 11 MDS patients with profoundly abnormal alphabeta TCR repertoires. This group of patients was characterized by advanced disease by International Prognostic Scoring System and World Health Organization criteria, increased expression of the Wilms' tumor-1 oncogene, increased bone marrow myeloblast count, and older age.

CONCLUSIONS

We have developed a robust analytic algorithm that enables the comparison of alphabeta TCR repertoires between individuals and have shown that abnormal alphabeta TCR repertoire is a feature of a subset of patients with advanced MDS.

Hypocellular myelodysplasia

Myelodysplasia must be considered in the differential diagnosis of patients who have bone marrow failure, but bone marrow cellularity per se may not substantially affect either response to therapy or prognosis. It is unclear whether the primary pathophysiologic defect differs between hyper- and hypoplastic patients who have myelodysplasia. Cellularity does not seem to affect response to immunosuppressive therapy significantly and does not seem to be the major factor affecting improvements in response to lenalidomide, stem cell transplantation, or hematopoietic growth factors.

Update on the therapy for myelodysplastic syndrome

The myelodysplastic syndromes (MDS) are a diverse group of clonal hematopoietic stem cell disorders characterized by cytopenias. Patients have a risk of developing acute leukemia though most succumb to complications of low blood counts. Over the past decade many novel treatments have been developed and investigation of new agents is ongoing. In this article, we discuss the classification and prognostic systems that are used in MDS, the agents available for treatment of MDS as well as review supportive and palliative care options for patients who are not candidates for, or opt against, newer treatment strategies.

Factors affecting response and survival in patients with myelodysplasia treated with immunosuppressive therapy

PURPOSE

Marrow failure in some patients with myelodysplastic syndrome (MDS) responds to immunosuppressive treatment (IST), but long-term outcome after IST has not been described. We evaluated patients with MDS treated with IST at our institution to determine their clinical course compared with a comparable supportive care only group.

PATIENTS AND METHODS

One hundred twenty-nine patients with MDS received IST with a median follow-up of 3.0 years (range, 0.03 to 11.3 years), using antithymocyte globulin (ATG) or cyclosporine (CsA) in combination or singly. Variables affecting response and survival were studied and outcomes were compared with those of 816 patients with MDS reported to the International Myelodysplasia Risk Analysis Workshop (IMRAW) who received only supportive care.

RESULTS

Thirty-nine (30%) of 129 patients receiving IST responded either completely or partially: 18 (24%) of 74 patients responded to ATG, 20 (48%) of 42 patients responded to ATG plus CsA, and one (8%) of 13 patients responded to CsA. Thirty-one percent (12 of 39) of the responses were complete, resulting in transfusion independence and near-normal blood counts. In multivariate analysis, younger age was the most significant factor favoring response to therapy. Other favorable factors affecting response were HLA-DR15 positivity and combination ATG plus CsA treatment (P = .001 and P = .048, respectively). In multivariate analysis of the combined IMRAW and IST cohorts, younger age, treatment with IST, and intermediate or low International Prognostic Scoring System score significantly favored survival.

CONCLUSION

IST produced significant improvement in the pancytopenia of a substantial proportion of patients with MDS and was associated with improved overall and progression-free survival, especially in younger individuals with lower-risk disease.

Low IPSS score and bone marrow hypocellularity in MDS patients predict hematological responses to antithymocyte globulin

Immunosuppressive therapy has been shown to induce sustained hematological responses in a subset of patients with myelodysplastic syndromes (MDS). In particular, antithymocyte globulin (ATG), a polyclonal immunoglobulin induces hematological responses in up to 60% of MDS patients. We report herein on the results of a retrospective multicenter study on the use of ATG in the treatment of 96 patients with MDS. Patients were evaluated for duration of response to ATG, as well as survival after administration of ATG. The median age of the cohort was 54.7 years (range: 19-75 years), with a median follow-up of 33.8 months (range: 0.8-133 months). A total of 40 patients (42%) achieved a hematological response, of which 30 patients (75%) had a durable hematological response lasting a median duration of 31.5 months (range: 6-92 months). On multivariate analysis, both low International Prognostic Scoring System (IPSS) and bone marrow (BM) hypocellularity were independent predictive factors for improved response to ATG (IPSS Int-2/high: odds ratio (OR) 0.08, P=0.018 and BM normo/hypercellularity: OR 0.49, P=0.012). In addition, IPSS was the sole predictor of overall survival, with Int-2/high risk patients having a significantly poorer survival outcome (OR 0.08, P<0.01). In conclusion, this study identifies BM hypocellularity and a low IPSS as important factors predicting response to ATG.