A prospective study of cyclosporine A treatment of patients with low-risk myelodysplastic syndrome: presence of CD55(-)CD59(-) blood cells predicts platelet response

Novel Molecular Mechanism of Lenalidomide in Myeloid Malignancies Independent of Deletion of Chromosome 5q

Lenalidomide as well as other immunomodulatory drugs (IMiDs) have achieved clinical efficacies in certain sub-types of hematologic malignancies, such as multiple myeloma, lower-risk myelodysplastic syndromes (MDS) with a single deletion of chromosome 5q (del(5q)) and others. Despite superior clinical response to lenalidomide in hematologic malignancies, relapse and resistance remains a problem in IMiD-based therapy. The last ten years have witnessed the discovery of novel molecular mechanism of IMiD-based anti-tumor therapy. IMiDs bind human cereblon (CRBN), the substrate receptor of the CRL4 E3 ubiquitin ligase complex. Binding of CRBN with IMiDs leads to degradation of the Ikaros family zinc finger proteins 1 and 3 (IKZF1 and IKZF3) and casein kinase 1 alpha. We have found that lenalidomide-mediated degradation of IKZF1 leads to activation of the G protein-coupled receptor 68 (GPR68)/calcium/calpain pro-apoptotic pathway and inhibition of the regulator of calcineurin 1 (RCAN1)/calcineurin pro-survival pathway in MDS and acute myeloid leukemia (AML). Calcineurin inhibitor Cyclosporin-A potentiates the anti-leukemia activity of lenalidomide in MDS/AML with or without del(5q). These findings broaden the therapeutic potential of IMiDs. This review summarizes novel molecular mechanism of lenalidomide in myeloid malignancies, especially without del(5q), in the hope to highlight novel therapeutic targets.

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.

Paroxysmal nocturnal hemoglobinuria testing in patients with myelodysplastic syndrome in clinical practice-frequency and indications

Background

Myelodysplastic syndrome (mds) is characterized by peripheral blood cytopenias, with most patients developing significant anemia and dependence on red blood cell (rbc) transfusion. In paroxysmal nocturnal hemoglobinuria (pnh), mutations in the PIGA gene lead to lack of cell-surface glycosylphosphatidylinositol, allowing complement-mediated lysis to occur. Paroxysmal nocturnal hemoglobinuria results in direct antiglobulin test-negative hemolysis and cytopenias, and up to 50% of patients with mds test positive for pnh cells. We wanted to determine whether pnh is considered to be a contributor to anemia in mds.

Methods

Patients with a diagnosis of mds confirmed by bone-marrow biopsy since 2009 were reviewed. High-resolution pnh testing by flow cytometry examined flaer (fluorescein-labeled proaerolysin) binding and expression of CD14, CD15, CD24, CD45, CD59, CD64, and CD235 on neutrophils, monocytes, and rbcs.

Results

In 152 patients with mds diagnosed in 2009 or later, the mds diagnosis included subtypes associated with pnh positivity (refractory anemia, n = 7, and hypoplastic mds, n = 4). Of 11 patients who underwent pnh testing, 1 was positive (9.0%). Reasons for pnh testing were anemia (n = 3), new mds diagnosis (n = 2), hypoplastic mds (n = 2), decreased haptoglobin (n= 1), increased rbc transfusion requirement (n= 1), and unexplained iron deficiency (n= 1).

Conclusions

Testing for pnh was infrequent in mds patients, and the criteria for testing were heterogeneous. Clinical indicators prompted pnh testing in 6 of 11 patients. Given that effective treatment is now available for pnh and that patients with pnh-positive mds can respond to immunosuppressive therapy, pnh testing in mds should be considered. Prospective analyses to clarify the clinical significance of pnh positivity in mds are warranted.

A Game of Clones: The Complex Interplay of Aplastic Anaemia, Myelodysplastic Syndrome, and Paroxysmal Nocturnal Haemoglobinuria

Although idiopathic aplastic anaemia (AA), myelodysplastic syndrome (MDS), and paroxysmal nocturnal haemoglobinuria (PNH) are all associated with bone marrow failure, they have traditionally been understood as distinct diseases with sharply contrasting pathophysiologies. These three disorders show considerable overlap. In 10% of cases of MDS the bone marrow is hypocellular, resembling AA, while glycophosphatidylinositol-deficient PNH cells can be detected in up to 5% of MDS and in >50% of AA patients. Results of recent studies offer a resolution to this overlap: MDS pathogenesis commonly has an autoimmune component and clonal haematopoiesis can be demonstrated in most cases of AA. Two explanations have arisen to explain the association of PNH with these disorders. It is hypothesised that PNH haematopoietic stem cells are relatively resistant to T cell attack and therefore have a competitive advantage in this context. Alternatively, it has been demonstrated that mutations associated with MDS are commonly present in PNH stem cells; such mutations could provide the PNH clone with an autonomous growth advantage. The authors suggest that these mechanisms may be necessary for the development of PNH in all cases, even when PNH occurs in the absence of MDS or AA. Finally, identification of a PNH clone is a predictive and prognostic biomarker in AA and MDS, adding important information for treatment and follow-up.

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.

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.

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.

Increased plasma thrombopoietin levels in patients with myelodysplastic syndrome: a reliable marker for a benign subset of bone marrow failure

Although myelodysplastic syndromes are heterogeneous disorders comprising a benign subset of bone marrow failure similar to aplastic anemia, no laboratory test has been established to distinguish it from bone marrow failures that can evolve into acute myeloid leukemia. Plasma thrombopoietin levels were measured in 120 patients who had myelodysplastic syndrome with thrombocytopenia (< 100 × 10(9)/L) to determine any correlation to markers associated with immune pathophysiology and outcome. Thrombopoietin levels were consistently low for patients with refractory anemia with excess of blasts, while patients with other myelodysplatic syndrome subsets had more variable results. Patients with thrombopoietin levels of 320 pg/mL and over had increased glycosylphosphatidylinositol-anchored protein-deficient blood cells (49.1% vs. 0%), were more likely to have a low International Prognostic Scoring System (IPSS) score (≤1.0, 100% vs. 65.5%), a higher response rate to immunosuppressive therapy (84.2% vs. 14.3%), and a better 5-year progression-free survival rate (94.1% vs. 63.6% for refractory cytopenia with unilineage dysplasia; 100.0% vs. 44.4% for refractory cytopenia with multilineage dysplasia). In conclusion, increased plasma thrombopoietin levels were associated with a favorable prognosis of bone marrow failure and could, therefore, represent a reliable marker for a benign subset of myelodysplastic syndrome.

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.

The small population of PIG-A mutant cells in myelodysplastic syndromes do not arise from multipotent hematopoietic stem cells

BACKGROUND

Patients with paroxysmal nocturnal hemoglobinuria harbor clonal glycosylphosphatidylinositol-anchor deficient cells arising from a multipotent hematopoietic stem cell acquiring a PIG-A mutation. Many patients with aplastic anemia and myelodysplastic syndromes also harbor small populations of glycosylphosphatidylinositol-anchor deficient cells. Patients with aplastic anemia often evolve into paroxysmal nocturnal hemoglobinuria; however, myelodysplastic syndromes seldom evolve into paroxysmal nocturnal hemoglobinuria. Here, we investigate the origin and clonality of small glycosylphosphatidylinositol-anchor deficient cell populations in aplastic anemia and myelodysplastic syndromes.

DESIGN AND METHODS

We used peripheral blood flow cytometry to identify glycosylphosphatidylinositol-anchor deficient blood cells, a proaerolysin-resistant colony forming cell assay to select glycosylphosphatidylinositol-anchor deficient progenitor cells, a novel T-lymphocyte enrichment culture assay with proaerolysin selection to expand glycosylphosphatidylinositol-anchor deficient T lymphocytes, and PIG-A gene sequencing assays to identify and analyze PIG-A mutations in patients with aplastic anemia and myelodysplastic syndromes.

RESULTS

Twelve of 15 aplastic anemia patients were found to harbor a small population of glycosylphosphatidylinositol-anchor deficient granulocytes; 11 of them were found to harbor a small population of glycosylphosphatidylinositol-anchor deficient erythrocytes, 10 patients were detected to harbor glycosylphosphatidylinositol-anchor deficient T lymphocytes, and 3 of them were detected only after T-lymphocyte enrichment in proaerolysin selection. PIG-A mutation analyses on 3 patients showed that all of them harbored a matching PIG-A mutation between CFU-GM and enriched T lymphocytes. Two of 26 myelodysplastic syndromes were found to harbor small populations of glycosylphosphatidylinositol-anchor deficient granulocytes and erythrocytes transiently. Bone marrow derived CD34(+) cells from 4 patients grew proaerolysin-resistant colony forming cells bearing PIG-A mutations. No glycosylphosphatidylinositol-anchor deficient T lymphocytes were detected in myelodysplastic syndrome patients.

CONCLUSIONS

In contrast to aplastic anemia and paroxysmal nocturnal hemoglobinuria, where PIG-A mutations arise from multipotent hematopoietic stem cells, glycosylphosphatidylinositol-anchor deficient cells in myelodysplastic syndromes appear to arise from more committed progenitors.

GPI-anchored protein-deficient T cells in patients with aplastic anemia and low-risk myelodysplastic syndrome: implications for the immunopathophysiology of bone marrow failure

Glycosylphosphatidylinositol-anchored protein-deficient (GPI-AP(-) ) T cells can be detected in some patients with bone marrow failure (BMF), but the link between these cells and BMF pathophysiology remains to be elucidated. To clarify the significance of GPI-AP(-) T cells in BMF, peripheral blood from 562 patients was examined for the presence of CD48(-) CD59(-) CD3(+) cells using high-resolution flow cytometry (FCM), and the GPI-AP(-) T cells were characterized with regard to their phenotype and sensitivity to inhibitory molecules, including herpesvirus entry mediator (HVEM) and a myelosuppressive cytokine, TGF-β. A multi-lineage FCM analysis detected CD48(-) CD59(-) CD3(+) T cells in 72 (12.8%) of the patients, together with GPI-AP(-) myeloid cells. Unexpectedly, 12 patients (10 with aplastic anemia and 2 with myelodysplastic syndrome-refractory anemia, 2.1%), who showed clinical features similar to those of other BMF patients with GPI-AP(-) myeloid cells, such as a good response to immunosuppressive therapy, displayed 0.01-0.3% GPI-AP(-) cells exclusively in T cells. The CD48(-) CD59(-) T cells consisted of predominantly effector memory (EM) and terminal effector cells, while CD48(-) CD59(-) T cells from non-BMF patients who had received anti-CD52 antibody only showed EM and central memory phenotypes. TGF-β and HVEM capable of inhibiting T-cell proliferation via its GPI-AP CD160 ligation suppressed the in vitro proliferation of GPI-AP(+) T cells more potently than that of GPI-AP(-) T cells from the same patients. The presence of GPI-AP(-) T cells, as well as GPI-AP(-) myeloid cells, may therefore reflect the immunopathophysiology of BMF in which cytokine-mediated suppression of hematopoietic stem cells via GPI-AP-type receptors takes place.

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.