T-cell immune responses to Wilms tumor 1 protein in myelodysplasia responsive to immunosuppressive therapy

Clonal cytopenia of undetermined significance (CCUS)-associated reversion of donor-derived, transient αβ T-cell large granular clonal lymphocytosis, emerging post-transplant in a patient with a history of γδ T-cell large granular lymphocytic leukemia

Autologous and allogeneic hematopoietic stem cell transplantation (HSCT) has revolutionized the therapy of hematolymphoid malignancies. Yet, how to best detect or predict the emergence of HSCT-related complications remain unresolved. Here, we describe a case of donor-derived, transient Alpha Beta (αβ) T-cell large granular clonal lymphocytosis and cytopenia that emerged post-HSCT in a patient with a history of gamma delta (γδ) T-cell large granular lymphocytic leukemia (T-LGLL). Clonal unrelatedness of post-transplant T-LGL lymphocytosis to the patient's pretransplant T-LGLL was first identified by T-cell receptor (TCR) PCR showing different sized fragments of rearranged gamma chains, in addition to shift from γδ to αβ TCR expression by flow cytometry analyses. Donor-derivation of the patient's post-transplant clonal lymphocytosis was confirmed by serial chimerism analyses of recipient's blood specimens demonstrating 100% donor DNA. Moreover, oncogenic DNMT3A and RUNX1 mutations were detected by next-generation sequencing (NGS) only in post-transplant specimens. Intriguingly, despite continued increase in DNMT3A and RUNX1 mutation load, the patient's clonal lymphocytosis and anemia eventually largely resolved; yet, the observed mutation profile with persistent thrombocytopenia indicated secondary clonal cytopenia of undetermined significance (CCUS) in the absence of overt morphologic evidence of myeloid neoplasm in the marrow. This case illustrates the utility of longitudinal chimerism analysis and NGS testing combined with flow cytometric immunophenotyping to evaluate emerging donor-derived hematolymphoid processes and to properly interpret partial functional engraftment. It may also support the notion that driver mutation-induced microenvironmental changes may paradoxically contribute to reestablishing tissue homeostasis.

Consequences of chromosome gain: A new view on trisomy syndromes

Chromosome gains are detrimental for the development of the human embryo. As such, autosomal trisomies almost always result in spontaneous abortion, and the rare embryos surviving until live birth suffer from a plethora of pathological defects. There is no treatment currently available to ameliorate the consequences of trisomies, such as Down syndrome (trisomy of chromosome 21). Identifying the source of the phenotypes observed in cells with extra chromosomes is crucial for understanding the underlying molecular causes of trisomy syndromes. Although increased expression of the genes localized on the extra chromosome triggers several pathological phenotypes, an alternative model suggests that global, aneuploidy-associated changes in cellular physiology also contribute to the pathology. Here, we compare the molecular consequences of trisomy syndromes in vivo against engineered cell lines carrying various chromosome gains in vitro. We point out several phenotypes that are shared by variable trisomies and, therefore, might be caused by the presence of an extra chromosome per se, independent of its identity. This alternative view may provide useful insights for understanding Down syndrome pathology and open additional opportunities for diagnostics and treatments.

Bone Marrow Immune Microenvironment in Myelodysplastic Syndromes

The BM, the major hematopoietic organ in humans, consists of a pleiomorphic environment of cellular, extracellular, and bioactive compounds with continuous and complex interactions between them, leading to the formation of mature blood cells found in the peripheral circulation. Systemic and local inflammation in the BM elicit stress hematopoiesis and drive hematopoietic stem cells (HSCs) out of their quiescent state, as part of a protective pathophysiologic process. However, sustained chronic inflammation impairs HSC function, favors mutagenesis, and predisposes the development of hematologic malignancies, such as myelodysplastic syndromes (MDS). Apart from intrinsic cellular mechanisms, various extrinsic factors of the BM immune microenvironment (IME) emerge as potential determinants of disease initiation and evolution. In MDS, the IME is reprogrammed, initially to prevent the development, but ultimately to support and provide a survival advantage to the dysplastic clone. Specific cellular elements, such as myeloid-derived suppressor cells (MDSCs) are recruited to support and enhance clonal expansion. The immune-mediated inhibition of normal hematopoiesis contributes to peripheral cytopenias of MDS patients, while immunosuppression in late-stage MDS enables immune evasion and disease progression towards acute myeloid leukemia (AML). In this review, we aim to elucidate the role of the mediators of immune response in the initial pathogenesis of MDS and the evolution of the disease.

Diagnosis of Myelodysplastic Syndromes: From Immunological Observations to Clinical Applications

Myelodysplastic syndromes (MDS) constitute a very heterogeneous group of diseases with a high prevalence in elderly patients and a propensity for progression to acute myeloid leukemia. The complexity of these hematopoietic malignancies is revealed by the multiple recurrent somatic mutations involved in MDS pathogenesis and the paradoxical common phenotype observed in these patients characterized by ineffective hematopoiesis and cytopenia. In the context of population aging, the incidence of MDS will strongly increase in the future. Thus, precise diagnosis and evaluation of the progression risk of these diseases are imperative to adapt the treatment. Dysregulations of both innate and adaptive immune systems are frequently detected in MDS patients, and their critical role in MDS pathogenesis is now commonly accepted. However, different immune dysregulations and/or dysfunctions can be dynamically observed during the course of the disease. Monitoring the immune system therefore represents a new attractive tool for a more precise characterization of MDS at diagnosis and for identifying patients who may benefit from immunotherapy. We review here the current knowledge of the critical role of immune dysfunctions in both MDS and MDS precursor conditions and discuss the opportunities offered by the detection of these dysregulations for patient stratification.

Single-Cell Technologies to Decipher the Immune Microenvironment in Myeloid Neoplasms: Perspectives and Opportunities

Myeloid neoplasms (MN) are heterogeneous clonal disorders arising from the expansion of hematopoietic stem and progenitor cells. In parallel with genetic and epigenetic dynamics, the immune system plays a critical role in modulating tumorigenesis, evolution and therapeutic resistance at the various stages of disease progression. Single-cell technologies represent powerful tools to assess the cellular composition of the complex tumor ecosystem and its immune environment, to dissect interactions between neoplastic and non-neoplastic components, and to decipher their functional heterogeneity and plasticity. In addition, recent progress in multi-omics approaches provide an unprecedented opportunity to study multiple molecular layers (DNA, RNA, proteins) at the level of single-cell or single cellular clones during disease evolution or in response to therapy. Applying single-cell technologies to MN holds the promise to uncover novel cell subsets or phenotypic states and highlight the connections between clonal evolution and immune escape, which is crucial to fully understand disease progression and therapeutic resistance. This review provides a perspective on the various opportunities and challenges in the field, focusing on key questions in MN research and discussing their translational value, particularly for the development of more efficient immunotherapies.

Hypoplastic myelodysplastic syndrome and acquired aplastic anemia: Immune‑mediated bone marrow failure syndromes (Review)

Hypoplastic myelodysplastic syndrome (hMDS) and aplastic anemia (AA) are rare hematopoietic disorders characterized by pancytopenia with hypoplastic bone marrow (BM). hMDS and idiopathic AA share overlapping clinicopathological features, making a diagnosis very difficult. The differential diagnosis is mainly based on the presence of dysgranulopoiesis, dysmegakaryocytopoiesis, an increased percentage of blasts, and abnormal karyotype, all favouring the diagnosis of hMDS. An accurate diagnosis has important clinical implications, as the prognosis and treatment can be quite different for these diseases. Patients with hMDS have a greater risk of neoplastic progression, a shorter survival time and a lower response to immunosuppressive therapy compared with patients with AA. There is compelling evidence that these distinct clinical entities share a common pathophysiology based on the damage of hematopoietic stem and progenitor cells (HSPCs) by cytotoxic T cells. Expanded T cells overproduce proinflammatory cytokines (interferon-γ and tumor necrosis factor-α), resulting in decreased proliferation and increased apoptosis of HSPCs. The antigens that trigger this abnormal immune response are not known, but potential candidates have been suggested, including Wilms tumor protein 1 and human leukocyte antigen class I molecules. Our understanding of the molecular pathogenesis of these BM failure syndromes has been improved by next-generation sequencing, which has enabled the identification of a large spectrum of mutations. It has also brought new challenges, such as the interpretation of variants of uncertain significance and clonal hematopoiesis of indeterminate potential. The present review discusses the main clinicopathological differences between hMDS and acquired AA, focuses on the molecular background and highlights the importance of molecular testing.

Looking beyond VEXAS: Coexistence of undifferentiated systemic autoinflammatory disease and myelodysplastic syndrome

It has been established that individuals with myelodysplastic syndromes (MDS) have a higher frequency of systemic inflammatory disorders. On the other hand, patients with autoimmune diseases are at increased risk of MDS development. Both diseases can be associated with various genetic lesions and share diverse pathogenetic mechanisms. Recently identified VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic) syndrome, associated with somatic mutations in UBA1, encompasses a range of inflammatory conditions involving multiple organs along with hematological pathologies, including MDS, as well as characteristic bone marrow vacuolization of myeloid and erythroid precursors. This novel syndrome drove further attention to complex associations between MDS and adult-onset inflammatory conditions. The present narrative literature review discusses the clinical presentation, pathophysiology, management of concurrent MDS and systemic inflammatory diseases in parallel to the clinical picture of VEXAS syndrome.

Immune Therapies for Myelodysplastic Syndromes and Acute Myeloid Leukemia

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are hematologic malignancies arising from the bone marrow. Despite recent advances in treating these diseases, patients with higher-risk MDS and AML continue to have a poor prognosis with limited survival. It has long been recognized that there is an immune component to the pathogenesis of MDS and AML, but until recently, immune therapies have played a limited role in treating these diseases. Immune suppressive therapy exhibits durable clinical responses in selected patients with MDS, but the question of which patients are most suitable for this treatment remains unclear. Over the past decade, there has been remarkable progress in identifying genomic features of MDS and AML, which has led to an improved discernment of the molecular pathogenesis of these diseases. An improved understanding of immune and inflammatory molecular mechanisms of MDS and AML have also recently revealed novel therapeutic targets. Emerging treatments for MDS and AML include monoclonal antibodies such as immune checkpoint inhibitors, bispecific T-cell-engaging antibodies, antibody drug conjugates, vaccine therapies, and cellular therapeutics including chimeric antigen receptor T-cells and NK cells. In this review, we provide an overview of the current understanding of immune dysregulation in MDS and AML and an update on novel immune therapies for these bone marrow malignancies.

Immunologic effects on the haematopoietic stem cell in marrow failure

Acquired bone marrow failure (BMF) syndromes comprise a diverse group of diseases with variable clinical manifestations but overlapping features of immune activation, resulting in haematopoietic stem and progenitor cells (HSPC) damage and destruction. This review focuses on clinical presentation, pathophysiology, and treatment of four BMF: acquired aplastic anaemia, large granular lymphocytic leukaemia, paroxysmal nocturnal haemoglobinuria, and hypoplastic myelodysplastic syndrome. Autoantigens are speculated to be the inciting event that result in immune activation in all of these diseases, but specific pathogenic antigens have not been identified. Oligoclonal cytotoxic T cell expansion and an active role of proinflammatory cytokines, primarily interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α), are two main contributors to HSPC growth inhibition and apoptosis in BMF. Emerging evidence also suggests involvement of the innate immune system.

Inflammatory and Immune Disorders Associated with Myelodysplastic Syndromes

Systemic auto-inflammatory or autoimmune diseases (SIADs) develop in up to a quarter of patients with myelodysplastic syndromes (MDS) or chronic myelomonocytic leukemia (CMML). With or without the occurrence of SIADs, the distribution of MDS subtypes and the international or CMML-specific prognostic scoring systems have been similar between MDS/CMML patients. Moreover, various SIADs have been described in association with MDS, ranging from limited clinical manifestations to systemic diseases affecting multiple organs. Defined clinical entities including systemic vasculitis, connective tissue diseases, inflammatory arthritis and neutrophilic diseases are frequently reported; however, unclassified or isolated organ impairment can also be seen. Although the presence of SIADs does not impact the overall survival nor disease progression to acute myeloid leukemia, they can help with avoiding steroid dependence and make associated adverse events of immunosuppressive drugs challenging. While therapies using steroids and immunosuppressive treatment remain the backbone of first-line treatment, increasing evidence suggests that MDS specific therapy (hypomethylating agents) and sparing steroids may be effective in treating such complications based on their immunomodulatory effect. The aim of this review was to analyze the epidemiological, pathophysiological, clinical and therapeutic factors of systemic inflammatory and immune disorders associated with MDS.

Autoimmune manifestations associated with myelodysplastic syndrome predict a poor prognosis

ABSTRACT

We evaluated the clinical characteristics of autoimmune manifestations (AIMs) associated with myelodysplastic syndrome (MDS) to elucidate whether AIMs impacted MDS outcomes in Japan.This retrospective study including 61 patients who received a new diagnosis of MDS between January 2008 and December 2015 was conducted by the review of electronic medical records for the presence of AIMs within a 1-year period prior to or following the diagnosis of MDS.AIMs were identified in 12 of the 61 (20.0%) patients with MDS. The neutrophil counts and C-reactive protein levels in peripheral blood were significantly elevated in patients with AIMs, and the survival was shorter in those with AIMs compared to those without AIMs. Multivariate analysis demonstrated that the presence of AIMs and higher-risk disease according to the International Prognositic Scoring System (IPSS) were independent risk factors for increased mortality (hazard ratio, 4.76 and 4.79, respectively).This retrospective study revealed that the prognosis was poor in patients with MDS-associated AIMs. The treatment of MDS using the current algorithms is based on prognostic scoring systems such as IPSS. Treatment strategies for patients with MDS-associated AIMs should be reconsidered, even in those with low-risk MDS according to the IPSS.

WT1-specific CD8 + cytotoxic T cells with the capacity for antigen-specific expansion accumulate in the bone marrow in MDS

Wilms' tumor 1 (WT1) is a tumor-associated antigen and immunotherapy target in myelodysplastic syndrome (MDS). Further information is needed on the characteristics of WT1-specific CD8 + T cells to develop immunotherapeutic strategies for MDS. To clarify the frequency, distribution, and phenotype of WT1-specific CD8 + T cells, which occur innately in MDS patients, we analyzed paired peripheral blood (PB) and bone marrow (BM) samples from 39 patients with MDS or acute myeloid leukemia with myelodysplasia-related changes. The median frequency of WT1 tetramer-binding CD8 + T cells in the CD8 + T cell population was 0.11% in PB and 0.18% in BM. A further tetramer assay combined with mixed lymphocyte peptide culture (MLPC assay) was used to detect functional WT1-specific CD8 + T cells that could respond to the WT1 peptide. Functional WT1-specific CD8 + T cells were detected in BM in 61% of patients, which was significantly higher than in PB (23%, p = 0.001). The frequency of these cells estimated by the MLPC assay was tenfold higher in BM than in PB. The majority of WT1 tetramer-binding CD8 + T cells in BM had a unique phenotype with co-expression of CD39 and CXCR4. These findings will facilitate the development of novel immunotherapeutic strategies for 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.

The acquisition of trisomy 8 associated with Behçet's-like disease in myelodysplastic syndrome

A relationship has been reported between myelodysplastic syndrome (MDS) and autoimmune disease. Behçet's disease is a multisystem inflammatory disorder with mucocutaneous, articular, gastrointestinal, neurological, and vascular manifestations. The co-occurrence of MDS with trisomy 8 and Behçet's-like disease was recently demonstrated. We herein describe a case that shows the relationship between the acquisition of trisomy 8 and occurrence of Behçet's-like disease. Immune dysregulation and altered T-cell hemostasis play an important role in the pathogenesis of Behçet's-like disease and MDS with trisomy 8.

Immune Dysregulation and Recurring Mutations in Myelodysplastic Syndromes Pathogenesis

Myelodysplastic syndromes (MDS) are clonal stem cell malignancies characterized by ineffective hematopoiesis leading to peripheral cytopenias and variable risk of progression to acute myeloid leukemia. Inflammation is associated with MDS pathogenesis. Several cytokines, reactive species of oxygen/nitrogen and growth factors are directly or indirectly involved in dysfunction of the MDS bone marrow (BM) microenvironment. Mutations in genes mainly regulating RNA splicing, DNA methylation and chromatin accessibility, transcription factors, signal transduction and the response to DNA damage contribute to ineffective hematopoiesis, genomic instability and MDS development. The inflammation-associated DNA damage in hematopoietic stem cells may also contribute to MDS development and progression with aggressive clinical characteristics. Many studies have aimed at clarifying mechanisms involved in the activity of immature myeloid cells as powerful modulators of the immune response and their correlation with aging, autoimmunity, and development of cancer. In this review, we explore recent advances and accumulating evidence uniting immune dysregulation, inflammaging and recurring mutations in the pathogenesis of MDS.

Effect of L-Leucine Therapy on Hematopoietic Function in Elderly Myelodysplastic Syndrome Patients

Patients with myelodysplastic syndrome (MDS) often require blood transfusion and anticancer therapy; however, elderly patients are intolerant to the associated side effects of anticancer therapy. Because L-leucine can be used to treat Diamond-Blackfan anemia, which is caused by defects in ribosomal protein (RP) genes, resulting in increased in vivo hemoglobin synthesis, it is possible that some MDS patients who have aberrations in their RP genes could also be effectively treated with L-leucine. In the present study, we investigated the effects of L-leucine on hematopoietic function (reticulocyte count), red blood cell count, and hemoglobin level in MDS patients. We administered L-leucine (1.8 g, twice daily, 3 d/week) with oral vitamin B6 supplements to a final cohort of eight MDS patients for 15 (interquartile range: 11-18) weeks. We assessed the patients at 10 ± 2 weeks after therapy initiation. Only the absolute reticulocyte count was affected, improving in 6/8 (75%) patients. The median absolute reticulocyte count was 3.5 × 10⁴ (range: 2.7-6.4 × 10⁴) cells/µL, an increase of 0.5 × 10⁴ (range: 0.2-0.7 × 10⁴) cells/µL. At 10 weeks, there was only one case of an improved hemoglobin level. Non-hematological adverse events of grade 3 were observed one raised triglycerides. These data suggest that L-leucine has little effect on MDS. However, it may contribute to the recovery of hematopoietic function, futher study be desired.

Treatment of myelodysplastic syndrome in the era of next-generation sequencing

Next-generation sequencing (NGS) is rapidly changing the clinical care of patients with myelodysplastic syndrome (MDS). NGS can be used for various applications: (i) in the diagnostic process to discriminate between MDS and other diseases such as aplastic anaemia, myeloproliferative disorders and idiopathic cytopenias; (ii) for classification, for example, where the presence of SF3B1 mutation is one criterion for the ring sideroblast anaemia subgroups in the World Health Organization 2016 classification; (iii) for identification of patients suitable for targeted therapy (e.g. IDH1/2 inhibitors); (iv) for prognostication, for example, where specific mutations (e.g. TP53 and RUNX1) are associated with inferior prognosis, whereas others (e.g. SF3B1) are associated with superior prognosis; and (v) to monitor patients for progression or treatment failure. Most commonly, targeted sequencing for genes (normally 50-100 genes) reported to be recurrently mutated in myeloid disease is used. At present, NGS is rarely incorporated into clinical guidelines although an increasing number of studies have demonstrated the benefit of using NGS in the clinical management of MDS patients.

Flaming and fanning: The Spectrum of inflammatory influences in myelodysplastic syndromes

The myelodysplastic syndromes (MDS) represent neoplasms derived from the expansion of mutated clonal hematopoietic cells which often demonstrate aberrant differentiation potential with resultant cytopenias and a propensity to evolve into acute myelogenous leukemia. While multiple mutations have been identified which may serve as drivers of the MDS clone, there is accumulating evidence that MDS clones and subclones are subject to modulation by the marrow microenvironment and its inflammatory milieu. There is also a strong link between autoimmune disorders and MDS. In this review, we examine the role of inflammatory cytokines, toll like receptors, pyroptosis, stromal cells, and cellular inflammatory mediators in MDS initiation, propagation, and progression. These contributions in a background of mutational, epigenetic, and aging changes in the marrow are also reviewed. Such inflammatory mediators may be subject to therapeutic agents which will enhance suppression of the MDS clone with potential to improve therapeutic outcomes in this disease which is usually incurable in aged patients not eligible for stem cell transplantation.

Immunosuppressive therapy in myelodysplastic syndromes: a borrowed therapy in search of the right place

INTRODUCTION

Myelodysplastic syndromes (MDS) encompass a heterogenous collection of clonal hematopoietic stem cell disorders defined by dysregulated hematopoiesis, peripheral cytopenias, and a risk of leukemic progression. Increasing data support the role of innate and adaptive immune pathways in the pathogenesis and disease course of MDS. The role of immunosuppressive therapy has an established role in the treatment of other hematologic diseases, such as aplastic anemia whose pathogenesis is postulated to reflect that of MDS with regards to many aspects of immune activation. Areas covered: This paper discusses the current understanding of immune dysregulation as it pertains to MDS, the clinical experience with immunosuppressive therapy in the management of MDS, as well as future prospects which will likely improve therapeutic options and outcomes for patients with MDS. Expert commentary: Though limited by paucity of high quality data, immunomodulatory and immunosuppressive therapies for the treatment of MDS have shown meaningful clinical activity in selected patients. Continued clarification of the immune pathways that are dysregulated in MDS and establishing predictors for clinical benefit of immunosuppressive therapy are vital to improve the use and outcomes with these therapies.

MDS shows a higher expression of hTERT and alternative splice variants in unactivated T-cells

Telomere instability and telomerase reactivation are believed to play an important role in the development of myelodysplastic syndromes (MDS). Abnormal enzymatic activity of human telomerase reverse transcriptase (hTERT), and its alternative splice variants have been reported to account for deregulated telomerase function in many cancers. In this study, we aim to compare the differences in expression of hTERT and hTERT splice variants, as well as telomere length and telomerase activity in unstimulated T-cells between MDS subgroups and healthy controls. Telomere length in MDS cases was significantly shorter than controls (n = 20, p<0.001) and observed across all subtypes of MDS using World Health Organization classification (WHO subgroups versus control: RARS, p= 0.009; RCMD, p=0.0002; RAEB1/2, p=0.004, respectively) and the International Prognostic Scoring System (IPSS subgroups: Low+Int-1, p<0.001; Int-2+High, p=0.004). However, unstimulated T-cells from MDS patients (n=20) had significantly higher telomerase activity (p=0.002), higher total hTERT mRNA levels (p=0.001) and hTERT α+β- splice variant expression (p<0.001) compared to controls. Other hTERT splice variants were lower in expression and not significantly different among cases and controls. Telomerase activity was positively correlated with total hTERT levels in MDS (r=0.58, p=0.007). This data is in sharp contrast to data published previously by our group showing a reduction in telomerase and hTERT mRNA in MDS T-cells after activation. In conclusion, this study provides additional insight into hTERT transcript patterns and activity in peripheral T-cells of MDS patients. Additional studies are necessary to better understand the role of this pathway in MDS development and progression.

Effect of IL-7 and IL-15 on T cell phenotype in myelodysplastic syndromes

Aberrant T cell phenotype is one of the characteristics of myelodysplastic syndromes (MDS). In this study, we detected an increased concentration of IL-15 in the plasma of MDS patients (n = 20) compared with that in the plasma of healthy controls (n = 20). In MDS patients, reduced naïve CD4+ and CD8+ T cells [16.11 ± 6.56 vs. 24.11 ± 7.18 for CD4+ T cells (p < 0.001) and 13.15 ± 5.67 vs. 23.51 ± 6.25 for CD8+ T cells (p < 0.001)] were observed. The reduced naïve and increased effector memory T cells were significantly correlated with IL-15 plasma level. Then, the effect of IL-15 and IL-7 was tested in vitro. Peripheral blood mononuclear cells from MDS were treated for 15 days with IL-15. This treatment significantly decreased naïve CD4+ (p < 0.001) and CD8+ (p < 0.001) T cells and correspondingly increased terminal memory CD4+ and CD8+ T cells (p < 0.001). Treatment with IL-7 increased naïve CD4+ (p < 0.05) and CD8+ (p < 0.001) T cells. Our results indicated that exposure to high levels of IL-15 may be involved in the T cell phenotype conversion observed in MDS. IL-7 may be one of the promising therapeutic candidates for recovering the effector immune compartment in MDS patients.

Comparison of T lymphocyte subsets in aplastic anemia and hypoplastic myelodysplastic syndromes

AIMS

This study aims to compare the proportion of peripheral blood T lymphocyte subsets and related blood cell and bone marrow cytology indexes between patients with aplastic anemia (AA) and hypoplastic myelodysplastic syndrome (hypo-MDS), and investigate the clinical identification significance.

MATERIALS AND METHODS

A total of 41 patients with AA and 46 patients with hypo-MDS were collected, and the proportions of peripheral blood T lymphocyte subsets, CD3^-CD16/CD56⁺NK cells, CD3⁺CD57⁺T-LGL cells and CD19⁺B lymphocytes were detected by flow cytometry.

KEY FINDINGS

The CD4⁺/CD8⁺ ratio decreased in the AA and hypo-MDS groups, and the difference was statistically significant when compared with that in the control group (P<0.05). However, there was no significant difference between AA and hypo-MDS groups (P>0.05). The proportions of CD3^-CD16/CD56⁺NK cells and CD3⁺CD57⁺T-LGL cells in the hypo-MDS group were distinctly higher than those in the AA group (P<0.05). However, the proportion of CD19⁺B lymphocyte was obviously lower than that in the AA group (P<0.05). Furthermore, the proportions of reticulocytes, bone marrow progenitor cells and immature red blood cells in the hypo-MDS group were significantly more than those in the AA group (P<0.05), and the proportion of mature lymphocytes in the hypo-MDS group was distinctly lower than that in the AA group (P<0.05).

SIGNIFICANCE

Changes of T lymphocyte subsets and the proportions of large granular lymphocytes and B lymphocytes can be utilized as indexes in the differential diagnosis between AA and hypo-MDS.

The immune landscape of myelodysplastic syndromes

Even though the pathogenesis of myelodysplastic syndromes (MDS) is dominated by specific molecular defects involving hematopoietic precursors, also immune mechanisms seem to play a fundamental functional role. In this review we will first describe the clinical and laboratory autoimmune manifestations often detectable in MDS patients. We will then focus on studies addressing the possible influence of different immune cell subpopulations on the disease onset and evolution. We will finally consider therapeutic approaches based on immunomodulation, ranging from immunosuppressants to vaccination and transplantation strategies.

Autoimmunity and Inflammation in Myelodysplastic Syndromes

Autoimmune and inflammatory conditions (AICs) are encountered in up to 25% of patients with myelodysplastic syndromes (MDS). A wide range of AICs have been reported in association with MDS and can range from limited clinical manifestations to systemic diseases affecting multiple organs. Vasculitides, connective tissue diseases, and inflammatory arthritis are frequently reported in different studies; noninfectious fever and constitutional symptoms at presentation are common. Associations between AICs and specific MDS characteristics vary by study, but the available data suggest that AICs cluster more often in younger patients with higher-risk MDS. In general, AICs do not seem to confer worse survival, although certain AICs may be associated with adverse outcome (e.g. vasculitis) or progression of MDS (Sweet's syndrome). Nonetheless, these complications may have a significant impact on quality of life and affect the timing and type of MDS-directed therapy. The mainstay of management of these complications in the short term relies on immunosuppressive drugs. Increasing evidence suggests that hypomethylating agents may be effective in treating these complications and reduce steroid dependence. While the pathogenesis of AICs is incompletely understood, growing appreciation of cellular immune deregulation, cytokine hypersecretion, and the genetic heterogeneity underlying MDS may improve our understanding of common pathways linking MDS, inflammation, and autoimmunity.

Immune Mechanisms in Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) is a spectrum of diseases, characterized by debilitating cytopenias and a propensity of developing acute myeloid leukemia. Comprehensive sequencing efforts have revealed a range of mutations characteristic, but not specific, of MDS. Epidemiologically, autoimmune diseases are common in patients with MDS, fueling hypotheses of common etiological mechanisms. Both innate and adaptive immune pathways are overly active in the hematopoietic niche of MDS. Although supportive care, growth factors, and hypomethylating agents are the mainstay of MDS treatment, some patients—especially younger low-risk patients with HLA-DR15 tissue type—demonstrate impressive response rates after immunosuppressive therapy. This is in contrast to higher-risk MDS patients, where several immune activating treatments, such as immune checkpoint inhibitors, are in the pipeline. Thus, the dual role of immune mechanisms in MDS is challenging, and rigorous translational studies are needed to establish the value of immune manipulation as a treatment of MDS.

T-cell large granular lymphocyte proliferation in myelodysplastic syndromes: Clinicopathological features and prognostic significance

Inflammatory and immune dysregulation are crucial in the initiation and development of myelodysplastic syndromes (MDS). It is noted that clonal T-cell large granular lymphocyte (T-LGL) proliferation associated with MDS is not uncommon. However, clinicopathological features, and prognostic and predictive value of presence of T-LGL proliferation in MDS patients is not very clear. This study compared 35 MDS patients with T-LGL proliferation with 36 MDS patients without T-LGL proliferation and summarized clinicopathologic features, including peripheral blood LGL cell counts, immunophenotype, T cell receptor gene rearrangement, bone marrow hematopoietic status, and adjuvant immunosuppressive therapy. The peripheral blood CD3+/CD57+ cell counts were significantly different (p<0.01) between the two groups. Notably, on examination of the bone marrow, MDS patients with T-LGL proliferation showed more frequent hypocellularity and/or lineage hypoplasia, particularly erythroid hypoplasia. On survival analysis, no overall difference was noted between MDS patients with T-LGL proliferation and those without T-LGL proliferation, and between the patients who received therapy for LGL and those who did not receive adjuvant therapy for LGL in the same risk group. In conclusion, T-LGL proliferation present in MDS patients can be associated with bone marrow hypocellularity and lineage hypoplasia. Although immunosuppressive therapy to eliminate T-LGL cells is potentially beneficial to the MDS patients with associated T-LGL proliferation, there is no overall survival benefit to the patients who received such treatment.

CMV-specific T cells generated from naïve T cells recognize atypical epitopes and may be protective in vivo

Adoptive transfer of cytomegalovirus (CMV)-specific T cells derived from adult seropositive donors can effectively restore antiviral immunity after transplantation. However, CMV-seronegative donors lack CMV-specific memory T cells, which restricts the availability of virus-specific T cells for immunoprophylaxis. We demonstrate the feasibility of deriving CMV-specific T cells from naïve cells for T cell therapy. Naïve T cells primed to recognize CMV were restricted to different, atypical epitopes than T cells derived from CMV-seropositive individuals; however, these two cell populations had similar avidities. CMV-seropositive individuals also had T cells recognizing these atypical epitopes, but these cells had a lower avidity than those derived from the seronegative subjects, which suggests that high-avidity T cells to these epitopes may be lost over time. Indeed, recipients of cord blood (CB) grafts who did not develop CMV were found by clonotypic analysis to have T cells recognizing atypical CMVpp65 epitopes. Therefore, we examined unmanipulated CB units and found that T cells with T cell receptors restricted by atypical epitopes were the most common, which may explain why these T cells expanded. When infused to recipients, naïve donor-derived virus-specific T cells that recognized atypical epitopes were associated with prolonged periods of CMV-free survival and complete remission. These data suggest that naïve-derived T cells from seronegative patients may be an additional source of cells for CMV immunoprophylaxis.

Higher Risk Myelodysplastic Syndromes in Patients with Well-Controlled HIV Infection: Clinical Features, Treatment, and Outcome

Introduction. In advanced HIV prior to combination antiretroviral therapy (ART), dysplastic marrow changes occurred and resolved with ART. Few reports of myelodysplastic syndromes (MDS) in well-controlled HIV exist and management is undefined. Methods. Patients with well-controlled HIV and higher risk MDS were identified; characteristics, treatment, and outcomes were reviewed. Results. Of 292 MDS patients since 1996, 1 (0.3%) was HIV-positive. A 56-year-old woman presented with cytopenias. CD4 was 1310 cells/mL and HIV viral load <40 copies/mL. Bone marrow biopsy showed RCMD and karyotype included del(5q) and del(7q); IPSS was intermediate-2 risk. She received azacitidine at 75% dose. Cycle 2, at full dose, was complicated by marrow aplasia and possible AML; she elected palliation. Three additional HIV patients with higher risk MDS, aged 56-64, were identified from the literature. All had deletions involving chromosomes 5 and 7. MDS treatment of 2 was not reported and one received palliation; all died of AML. Conclusion. Four higher risk MDS in well-controlled HIV were below the median age of diagnosis for HIV-negative patients; all had adverse karyotype. This is the first report of an HIV patient receiving MDS treatment with azacitidine. Cytopenias were profound and dosing in HIV patients should be considered with caution.

Analysis of the functional WT1-specific T-cell repertoire in healthy donors reveals a discrepancy between CD4(+) and CD8(+) memory formation

The Wilms' tumour-1 (WT1) protein is considered a prime target for cancer immunotherapy based on its presumptive immunogenicity and widespread expression across a variety of malignancies. However, little is known about the naturally occurring WT1-specific T-cell repertoire because self-derived antigens typically elicit low frequency responses that challenge the sensitivity limits of current detection techniques. In this study, we used highly efficient cell enrichment procedures based on CD137, CD154, and pHLA class I tetramer staining to conduct a detailed analysis of WT1-specific T cells from the peripheral blood. Remarkably, we detected WT1-specific CD4(+) and CD8(+) T-cell populations in the vast majority of healthy individuals. Memory responses specific for WT1 were commonly present in the CD4(+) T-cell compartment, whereas WT1-specific CD8(+) T cells almost universally displayed a naive phenotype. Moreover, memory CD4(+) and naive CD8(+) T cells with specificity for WT1 were found to coexist in some individuals. Collectively, these findings suggest a natural discrepancy between the CD4(+) and CD8(+) T-cell lineages with respect to memory formation in response to a self-derived antigen. Nonetheless, WT1-specific T cells from both lineages were readily activated ex vivo and expanded in vitro, supporting the use of strategies designed to exploit this expansive reservoir of self-reactive T cells for immunotherapeutic purposes.

Chronic relapsing remitting Sweet syndrome--a harbinger of myelodysplastic syndrome

Sweet syndrome (SS) is an acute febrile neutrophilic dermatosis. It has been associated with malignant disease, especially acute myeloid leukaemia (AML), infections, autoimmune disorders and drugs, particularly granulocyte colony-stimulating factor (GCSF). No cause is found in the rest, which are labelled idiopathic. We describe 15 patients with SS, which we believe represent 'immune dysregulation' secondary to myelodysplastic syndrome (MDS). We initially identified 31 patients with SS in a cohort of 744 patients with MDS and 215 with AML seen over a 6-year period (2004-10). The cause in 16 patients could be attributed either to administration of GCSF or chemotherapy. The eruption was brief and resolved spontaneously or following withdrawal of GCSF. Fifteen patients however, had a chronic debilitating illness dominated by the skin eruptions. Diagnosis of chronic relapsing SS was delayed because the pathology was not always typical of classical neutrophil-rich SS and included lymphocytic and histiocytoid infiltrates and bone marrow was not always performed because the relevance of the eruption to MDS was often not immediately appreciated. All these patients had 'low risk' MDS, diagnosed at a median of 17 months (range 0-157) following the diagnosis of SS. We describe a chronic debilitating episodic clinically distinctive skin eruption with features of SS but not always definitive histopathology often associated with immunological abnormalities affecting other systems related to underlying low risk MDS.

Molecular mechanisms of the progression of myelodysplastic syndrome to secondary acute myeloid leukaemia and implication for therapy

Myelodysplastic syndrome (MDS) includes a heterogeneous group of clonal haematological stem cell disorders characterized by dysplasia, cytopenias, ineffective haematopoiesis, and an increased risk of progression to acute myeloid leukaemia (AML), which is also called secondary AML (sAML). Approximately one-third of patients with MDS will progress to sAML within a few months to a few years, and this type of transformation is more common and rapid in patients with high-risk MDS (HR-MDS). However, the precise mechanisms underlying the evolution of MDS to sAML remain unclear. Currently, chemotherapy for sAML has minimal efficacy. The only method of curing patients with sAML is allogeneic haematopoietic stem cell transplantation (Allo-HSCT). Unfortunately, only a few patients are appropriate for transplantation because this disease primarily affects older adult patients. Additionally, compared to de novo AML, sAML is more difficult to cure, and the prognosis is often worse. Therefore, it is important to clarify the molecular mechanisms of the progression of MDS to sAML and to explore the potent drugs for clinical use. This review will highlight several molecular mechanisms of the progression of MDS to sAML and new therapeutic strategies of this disease.

Deregulation of innate immune and inflammatory signaling in myelodysplastic syndromes

Myelodysplastic syndromes (MDSs) are a group of heterogeneous clonal hematologic malignancies that are characterized by defective bone marrow (BM) hematopoiesis and by the occurrence of intramedullary apoptosis. During the past decade, the identification of key genetic and epigenetic alterations in patients has improved our understanding of the pathophysiology of this disease. However, the specific molecular mechanisms leading to the pathogenesis of MDS have largely remained obscure. Recently, essential evidence supporting the direct role of innate immune abnormalities in MDS has been obtained, including the identification of multiple key regulators that are overexpressed or constitutively activated in BM hematopoietic stem and progenitor cells. Mounting experimental results indicate that the dysregulation of these molecules leads to abnormal hematopoiesis, unbalanced cell death and proliferation in patients' BM, and has an important role in the pathogenesis of MDS. Furthermore, there is compelling evidence that the deregulation of innate immune and inflammatory signaling also affects other cells from the immune system and the BM microenvironment, which establish aberrant associations with hematopoietic precursors and contribute to the MDS phenotype. Therefore, the deregulation of innate immune and inflammatory signaling should be considered as one of the driving forces in the pathogenesis of MDS. In this article, we review and update the advances in this field, summarizing the results from the most recent studies and discussing their clinical implications.

Pathogenesis of myelodysplastic syndromes: an overview of molecular and non-molecular aspects of the disease

Myelodysplastic syndromes (MDS) are a group of clonal disorders arising from hematopoietic stem cells generally characterized by inefficient hematopoiesis, dysplasia in one or more myeloid cell lineages, and variable degrees of cytopenias. Most MDS patients are diagnosed in their late 60s to early 70s. The estimated incidence of MDS in the United States and in Europe are 4.3 and 1.8 per 100,000 individuals per year, respectively with lower rates reported in some Asian countries and less well estimated in other parts of the world. Evolution to acute myeloid leukemia can occur in 10-15% of MDS patients. Three drugs are currently approved for the treatment of patients with MDS: immunomodulatory agents (lenalidomide), and hypomethylating therapy [HMT (decitabine and 5-azacytidine)]. All patients will eventually lose their response to therapy, and the survival outcome of MDS patients is poor (median survival of 4.5 months) especially for patients who fail (refractory/relapsed) HMT. The only potential curative treatment for MDS is hematopoietic cell transplantation. Genomic/chromosomal instability and various mechanisms contribute to the pathogenesis and prognosis of the disease. High throughput genetic technologies like single nucleotide polymorphism array analysis and next generation sequencing technologies have uncovered novel genetic alterations and increased our knowledge of MDS pathogenesis. We will review various genetic and non-genetic causes that are involved in the pathogenesis of MDS.

Effector memory regulatory T-cell expansion marks a pivotal point of immune escape in myelodysplastic syndromes

Myleodysplastic syndromes (MDS) are pre-malignant hematopoietic diseases that can progress to acute myeloid leukemia (AML) progression in conjunction with changes in immune function. In this model of leukemia evolution, the expansion of immunosuppressive regulatory T cells (Tregs) contributes to immune escape. Here, we discuss the importance of Treg-memory phenotype switching as a poor prognostic indicator in MDS.

T-cell-restricted T-bet overexpression induces aberrant hematopoiesis of myeloid cells and impairs function of macrophages in the lung

Although overexpression of T-bet, a master transcription factor in type-1 helper T lymphocytes, has been reported in several hematologic and immune diseases, its role in their pathogenesis is not fully understood. In the present study, we used transgenic model mice (T-bet(tg/wt) and T-bet(tg/tg)) to investigate the effects of T-bet overexpression selectively in T lymphocytes on the development of hematologic and immune diseases. The results showed that T-bet overexpression in T cells spontaneously induced maturation arrest in the mononuclear phagocyte lineage, as well as spontaneous dermatitis and pulmonary alveolar proteinosis (PAP)-like disease in T-bet(tg/wt) and T-bet(tg/tg) mice, respectively. T-bet(tg/tg) alveoli with the PAP phenotype showed remarkable reorganization of alveolar mononuclear phagocyte subpopulations and impaired function, in addition to augmented T-cell infiltration. In addition, PAP development in T-bet(tg/tg) mice was found to be associated with increased migration of myeloid cells from the bone marrow into the peripheral blood. These findings reveal an unexpected link between T-bet overexpression in T lymphocytes and the development of PAP caused by reorganization of mononuclear phagocytes in the lung, and provide new insight into the molecular pathogenesis of secondary PAP accompanied by hematologic disorders.

The challenging world of cytopenias: distinguishing myelodysplastic syndromes from other disorders of marrow failure

Over the past decade, our understanding of bone marrow failure has advanced considerably. Marrow failure encompasses multiple overlapping diseases, and there is increasing availability of diagnostic tools to distinguish among the subtypes. Identification of genetic alterations that underlie marrow failure has also greatly expanded, especially for myelodysplastic syndromes. Molecular markers are increasingly used to guide the management of myelodysplasia and may distinguish this diagnosis from other marrow failure disorders. This review summarizes the current state of distinguishing among causes of marrow failure and discusses the potential uses of multiple diagnostic and prognostic indicators in the management of myelodysplastic syndromes and other bone marrow failure disorders.

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.

Immunological derangement in hypocellular myelodysplastic syndromes

Hypocellular or hypoplastic myelodysplastic syndromes (HMDS) are a distinct subgroup accounting for 10-15% of all MDS patients, that are characterized by the presence of bone marrow (BM) hypocellularity, various degree of dysmyelopoiesis and sometimes abnormal karyotype. Laboratory and clinical evidence suggest that HMDS share several immune-mediated pathogenic mechanisms with acquired idiopathic aplastic anemia (AA). Different immune-mediated mechanisms have been documented in the damage of marrow hematopoietic progenitors occurring in HMDS; they include oligoclonal expansion of cytotoxic T lymphocytes (CTLs), polyclonal expansion of various subtypes of T helper lymphocytes, overexpression of FAS-L and of the TNF-related apoptosis-inducing ligand (TRAIL), underexpression of Flice-like inhibitory protein long isoform (FLIPL) in marrow cells as well as higher release of Th1 cytokines, such as interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α). It has also been documented that some HMDS patients have higher frequency of polymorphisms linked both to high production of proinflammatory cytokines such as TNF-α and transforming growth factor-β and to the inhibition of T-cell mediated immune responses such as interleukin-10, further suggesting that immune-mediated mechanisms similar to those seen in AA patients may also operate in HMDS. Clinically, the strongest evidence for immune-mediated hematopoietic suppression in some HMDS is the response to immunosuppression including mainly cyclosporine, anti-thymocyte globulin and/or cyclosporine, or alemtuzumab. Here we review all these immune mechanisms as well as the influence of this deranged cellular and humoral immunologic mileau on the initiation and possible progression of MDS. All these observations are pivotal not only for a better understanding of MDS pathophysiology, but also for their immediate clinical implications, eventually leading to the identification of MDS patients who may benefit from immunosuppression.

Genetically engineered fixed K562 cells: potent "off-the-shelf" antigen-presenting cells for generating virus-specific T cells

BACKGROUND AIMS

The human leukemia cell line K562 represents an attractive platform for creating artificial antigen-presenting cells (aAPC). It is readily expandable, does not express human leukocyte antigen (HLA) class I and II and can be stably transduced with various genes.

METHODS

In order to generate cytomegalovirus (CMV) antigen-specific T cells for adoptive immunotherapy, we transduced K562 with HLA-A∗0201 in combination with co-stimulatory molecules.

RESULTS

In preliminary experiments, irradiated K562 expressing HLA-A∗0201 and 4-1BBL pulsed with CMV pp65 and IE-1 peptide libraries failed to elicit antigen-specific CD8⁺ T cells in HLA-A∗0201⁺ peripheral blood mononuclear cells (PBMC) or isolated T cells. Both wild-type K562 and aAPC strongly inhibited T cell proliferation to the bacterial superantigen staphylococcal enterotoxin B (SEB) and OKT3 and in mixed lymphocyte reaction (MLR). Transwell experiments suggested that suppression was mediated by a soluble factor; however, MLR inhibition was not reversed using transforming growth factor-β blocking antibody or prostaglandin E2 inhibitors. Full abrogation of the suppressive activity of K562 on MLR, SEB and OKT3 stimulation was only achieved by brief fixation with 0.1% formaldehyde. Fixed, pp65 and IE-1 peptide-loaded aAPC induced robust expansion of CMV-specific T cells.

CONCLUSIONS

Fixed gene-modified K562 can serve as effective aAPC to expand CMV-specific cytotoxic T lymphocytes for therapeutic use in patients after stem cell transplantation. Our findings have implications for broader understanding of the immune evasion mechanisms used by leukemia and other tumors.

Comparison of horse and rabbit antithymocyte globulin in immunosuppressive therapy for refractory cytopenia of childhood

Refractory cytopenia of childhood is the most common subtype of myelodysplastic syndrome in children. In this study, we compared the outcome of immunosuppressive therapy using horse antithymocyte globulin (n=46) with that using rabbit antithymocyte globulin (n=49) in 95 patients with refractory cytopenia of childhood and hypocellular bone marrow. The response rate at 6 months was 74% for horse antithymocyte globulin and 53% for rabbit antithymocyte globulin (P=0.04). The inferior response in the rabbit antithymocyte globulin group resulted in lower 4-year transplantation-free (69% versus 46%; P=0.003) and failure-free (58% versus 48%; P=0.04) survival rates in this group compared with those in the horse antithymocyte globulin group. However, because of successful second-line hematopoietic stem cell transplantation, overall survival was comparable between groups (91% versus 85%; P=ns). The cumulative incidence of relapse (15% versus 9%; P=ns) and clonal evolution (12% versus 4%; P=ns) at 4 years was comparable between groups. Our results suggest that the outcome of immunosuppressive therapy with rabbit antithymocyte globulin is inferior to that of horse antithymocyte globulin. Although immunosuppressive therapy is an effective therapy in selected patients with refractory cytopenia of childhood, the long-term risk of relapse or clonal evolution remains. (ClinicalTrial.gov identifiers: NCT00662090).

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.

Lentivirus-induced dendritic cells for immunization against high-risk WT1(+) acute myeloid leukemia

Wilms' tumor 1 antigen (WT1) is overexpressed in acute myeloid leukemia (AML), a high-risk neoplasm warranting development of novel immunotherapeutic approaches. Unfortunately, clinical immunotherapeutic use of WT1 peptides against AML has been inconclusive. With the rationale of stimulating multiantigenic responses against WT1, we genetically programmed long-lasting dendritic cells capable of producing and processing endogenous WT1 epitopes. A tricistronic lentiviral vector co-expressing a truncated form of WT1 (lacking the DNA-binding domain), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-4 (IL-4) was used to transduce human monocytes ex vivo. Overnight transduction induced self-differentiation of monocytes into immunophenotypically stable "SmartDC/tWT1" (GM-CSF(+), IL-4(+), tWT1(+), IL-6(+), IL-8(+), TNF-α(+), MCP-1(+), HLA-DR(+), CD86(+), CCR2(+), CCR5(+)) that were viable for 3 weeks in vitro. SmartDC/tWT1 were produced with peripheral blood mononuclear cells (PBMC) obtained from an FLT3-ITD(+) AML patient and surplus material from a donor lymphocyte infusion (DLI) and used to expand CD8(+) T cells in vitro. Expanded cytotoxic T lymphocytes (CTLs) showed antigen-specific reactivity against WT1 and against WT1(+) leukemia cells. SmartDC/tWT1 injected s.c. into Nod.Rag1(-/-).IL2rγc(-/-) mice were viable in vivo for more than three weeks. Migration of human T cells (huCTLs) to the immunization site was demonstrated following adoptive transfer of huCTLs into mice immunized with SmartDC/tWT1. Furthermore, SmartDC/tWT1 immunization plus adoptive transfer of T cells reactive against WT1 into mice resulted in growth arrest of a WT1(+) tumor. Gene array analyses of SmartDC/tWT1 demonstrated upregulation of several genes related to innate immunity. Thus, SmartDC/tWT1 can be produced in a single day of ex vivo gene transfer, are highly viable in vivo, and have great potential for use as immunotherapy against malignant transformation overexpressing WT1.

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.