Platelet dysfunction in myelodysplastic syndromes: a clinicopathological study

Myelodysplastic Syndromes in the Postgenomic Era and Future Perspectives for Precision Medicine

Simple Summary

With demographic ageing, improved cancer survivorship and increased diagnostic sensitivity, incident cases of patients with Myelodysplastic Syndromes (MDS) are continuously rising, leading to a relevant impact on health care resources. Disease heterogeneity and various comorbidities are challenges for the management of the generally elderly patients. Therefore, experienced physicians and multidisciplinary teams should be involved in the establishment of the correct diagnosis, risk-assessment and personalized treatment plan. Next-generation sequencing allows for early detection of clonal hematopoiesis and monitoring of clonal evolution, but also poses new challenges for its appropriate use. At present, allogeneic hematopoietic stem cell transplantation remains the only curative treatment option for a minority of fit MDS patients. All others receive palliative treatment and will eventually progress, having an unmet need for novel therapies. Targeting compounds are in prospect for precision medicine, however, abrogation of clonal evolution to acute myeloid leukemia remains actually out of reach.

Abstract

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal disorders caused by sequential accumulation of somatic driver mutations in hematopoietic stem and progenitor cells (HSPCs). MDS is characterized by ineffective hematopoiesis with cytopenia, dysplasia, inflammation, and a variable risk of transformation into secondary acute myeloid leukemia. The advent of next-generation sequencing has revolutionized our understanding of the genetic basis of the disease. Nevertheless, the biology of clonal evolution remains poorly understood, and the stochastic genetic drift with sequential accumulation of genetic hits in HSPCs is individual, highly dynamic and hardly predictable. These continuously moving genetic targets pose substantial challenges for the implementation of precision medicine, which aims to maximize efficacy with minimal toxicity of treatments. In the current postgenomic era, allogeneic hematopoietic stem cell transplantation remains the only curative option for younger and fit MDS patients. For all unfit patients, regeneration of HSPCs stays out of reach and all available therapies remain palliative, which will eventually lead to refractoriness and progression. In this review, we summarize the recent advances in our understanding of MDS pathophysiology and its impact on diagnosis, risk-assessment and disease monitoring. Moreover, we present ongoing clinical trials with targeting compounds and highlight future perspectives for precision medicine.

When Should We Think of Myelodysplasia or Bone Marrow Failure in a Thrombocytopenic Patient? A Practical Approach to Diagnosis

Thrombocytopenia can arise from various conditions, including myelodysplastic syndromes (MDS) and bone marrow failure (BMF) syndromes. Meticulous assessment of the peripheral blood smear, identification of accompanying clinical conditions, and characterization of the clinical course are important for initial assessment of unexplained thrombocytopenia. Increased awareness is required to identify patients with suspected MDS or BMF, who are in need of further investigations by a step-wise approach. Bone marrow cytomorphology, histopathology, and cytogenetics are complemented by myeloid next-generation sequencing (NGS) panels. Such panels are helpful to distinguish reactive cytopenia from clonal conditions. MDS are caused by mutations in the hematopoietic stem/progenitor cells, characterized by cytopenia and dysplasia, and an inherent risk of leukemic progression. Aplastic anemia (AA), the most frequent acquired BMF, is immunologically driven and characterized by an empty bone marrow. Diagnosis remains challenging due to overlaps with other hematological disorders. Congenital BMF, certainly rare in adulthood, can present atypically with thrombocytopenia and can be misdiagnosed. Analyses for chromosome fragility, telomere length, and germline gene sequencing are needed. Interdisciplinary expert teams contribute to diagnosis, prognostication, and choice of therapy for patients with suspected MDS and BMF. With this review we aim to increase the awareness and provide practical approaches for diagnosis of these conditions in suspicious cases presenting with thrombocytopenia.

Thrombocytopenia: Perioperative Considerations for Patients Undergoing Cardiac Surgery

The etiologies of thrombocytopenia in patients presenting for cardiac surgery are extensive, but clinically relevant conditions generally can be categorized by those related to decreased platelet production or increased platelet destruction. Many causes require mere acknowledgment and availability of allogeneic platelet transfusion; others have unique considerations for which providers should be familiar. The purpose of this review is to provide an overview of the common causes of thrombocytopenia, summarize the literature, and discuss perioperative considerations for patients undergoing cardiac surgery.

Acquired hemophilia A and delta storage pool deficiency in a patient with indolent non-Hodgkin lymphoma

B-cell lymphoproliferative diseases may be associated with acquired hemostasis disorders, such as acquired hemophilia A (AHA) caused by autoantibodies that neutralize factor VIII activity, and δ-storage pool deficiency, an abnormality of platelet function due to defective dense granules and impaired secretion. We describe the case of a 67-year-old man in whom these two acquired bleeding disorders were concomitantly present as the first clinical manifestation of an indolent non-Hodgkin lymphoma. Immunosuppressive therapy with prednisone was initially started to eradicate anti-FVIII antibodies, subsequently boosted with cyclophosphamide and rituximab, these medications being also chosen to treat the associated indolent lymphoma. Bleeding symptoms were first tackled with limited benefit by using rFVIIa and then rescued using recombinant porcine FVIII. After a 6 month's follow-up lymphoma and AHA were in remission and platelet function was improved. This case underlines the need of multiple and complex diagnostic and therapeutic approaches to rare acquired bleeding disorders associated with lymphoproliferative diseases.

Abnormal platelet phenotypes in patients with myelodysplastic syndromes

INTRODUCTION

Hemorrhage and infection are two main causes of death in patients with myelodysplastic syndromes (MDS), and it is becoming increasingly clear that platelet dysfunction can also affect the process of hemostasis and anti-infection. The aim of this study was to evaluate activation function and immune-related function of platelets in MDS.

METHODS

We included 29 MDS patients and divided them into different subgroups (low-risk group and high-risk group; untreated group and treated group; pretransfusion group and post-transfusion group) according to IPSS-R score, hypomethylating agents (HMAs) therapy, and platelet transfusion history. Platelet light scatter properties, expression of CD41a, activation-associated phenotypes (CD62p and CD63), and immune-associated phenotypes (CD154 and TLR4) were detected by multiparameter flow cytometry.

RESULTS

Expression of CD41a was decreased (P < .05), and no difference was found in platelet light scatter properties between MDS patients and healthy subjects (P > .05). Significantly decreased expression frequency and intensity of activation phenotype CD63 were found in patients with MDS (P < .05). Low-risk MDS showed lower expression frequency while high-risk MDS showed reduced mean fluorescence intensity (MFI) of CD63. Decreased expression of CD154 and TLR4 was found in MDS patients (P < .05) which was significantly elevated after HMAs therapy (P < .05). Particularly, MFI of CD154 and TLR4 reduced in high-risk MDS patients (P < .05).

CONCLUSION

Myelodysplastic syndromes patients displayed defective expression of both activation- and immune-associated platelet phenotypes, with differential mechanisms between low-risk and high-risk groups regarding phenotype alterations. The findings confirmed impaired platelet phenotypes in MDS which may assist in the diagnosis and identification of MDS patients.

Acquired platelet dysfunction and overproduction of platelet cyclic AMP in two patients with myeloid malignancies

The pathophysiology of impaired platelet function in acquired disorders is often poorly understood. We report two unrelated patients with hematologic malignancies associated with acquired severe bleeding diathesis, and complex platelet function abnormalities, including overproduction of the physiological inhibitor cyclic-AMP (cAMP). Patient 1, with mild macrocytic anemia and thrombocytopenia (100 x 10⁹/L), was diagnosed with chronic myelomonocytic leukemia a few months after the onset of her bleeding diathesis and our analysis of platelet function. Patient 2, with bleeding diathesis of recent onset, was studied when his myelodysplastic syndrome with excess blasts had already progressed to acute myeloid leukemia. In both patients, platelet aggregation/ATP secretion, serum thromboxane B₂, intraplatelet content of ADP, ATP, serotonin, and fibrinogen were severely impaired. Baseline platelet cAMP levels were mildly elevated and markedly increased after stimulation by prostaglandin E₁. In conclusion, these are the first patients with myeloid malignancies associated with acquired severe platelet dysfunction and overproduction of cAMP.

Acquired platelet function disorders

The possibility of an acquired platelet function disorder should be considered in patients who present with recent onset muco-cutaneous bleeding. Despite the availability of newer and faster platelet function assays, light transmission aggregometry (LTA) remains the preferred diagnostic test. This review examines and discusses the causes of acquired platelet dysfunction; most commonly drugs, dietary factors, medical disorders and procedures. In addition to well-known antiplatelet therapies, clinicians should be alert for newer drugs which can affect platelets, such as ibrutinib. There is little clinical trial evidence to guide the management of acquired platelet function defects, but we summarise commonly employed strategies, which include addressing the underlying cause, antifibrinolytic agents, desmopressin infusions, and in selected patients, platelet transfusions.

Myelodysplastic Syndromes: Laboratory Workup in the Context of New Concepts and Classification Criteria

PURPOSE OF REVIEW

This review provides a comprehensive update of myelodysplastic syndromes (MDS) and their diagnostic criteria, with emphasis on novel concepts and state-of-the-art laboratory workup, including multiparameter/multicolor flow cytometry, chromosome analysis, and mutation profiling.

RECENT FINDINGS

Recent advances in genetics and molecular technologies have provided unprecedented insights into the pathogenic mechanisms and genomic landscape of MDS and its precursor lesions. This has resulted in revised diagnostic criteria in the World Health Organization (WHO) classification and proposed new terminology for early lesions such as clonal hematopoiesis of indeterminate potential (CHIP). Against this landscape, a thorough understanding of the advantages and limitations of laboratory tests employed in the evaluation of patients with cytopenia has gained unprecedented importance. Healthcare providers involved in the care of patients with hematologic diseases should be aware of the intricacies of laboratory workup of such patients, particularly in view of the novel concepts and classification criteria of MDS.

Eight-ball hyphema after laser iridotomy in a patient with undiagnosed hypocellular myelodysplastic syndrome

Introduction

We report a rare case of unexpected gross hyphema in the right eye (OD) and eight-ball hyphema in the left eye (OS) from a bilateral laser iridotomy in an acute primary angle-closure patient. We also demonstrated the effectiveness of the inferior full-thickness trabeculectomy with daily intracameral air injection as an alternative treatment in eight-ball hyphema.

Case report

An 81-year-old Thai female presented with gross hyphema grade II OD and eight-ball hyphema with blood-stained cornea OS after laser iridotomy. The patient was scheduled for surgery and the preoperative blood test showed bicytopenia. We performed anterior chamber washout OD and an inferior full-thickness trabeculectomy with daily intracameral air injection OS. The hyphema completely resolved on the following day OD and 3 days after surgery OS. The inferior bleb OS did not raise with digital pressure and became nonfunctional in 7 days. No recurrent hyphema was found in both eyes (OU) during 6 months of follow-up. This patient was ultimately diagnosed with hypocellular myelodysplastic syndrome (MDS).

Conclusion

Gross hyphema after laser iridotomy can be seen in patients with hypocellular MDS. The inferior full-thickness trabeculectomy is an alternative surgical procedure for an eight-ball hyphema.

Antiplatelet Therapy in a Patient with Coronary Artery Disease and Myelodysplastic Syndrome with Thrombocytopenia

To date, there are no sufficient data to make firm recommendations on the treatment of patients with severe thrombocytopenia who require antiplatelet therapy after experiencing acute coronary syndrome. Therefore, we think that it is important to communicate the experience with individual cases. We report the case of a patient who presented with pericardial effusion causing cardiac tamponade. He had thrombocytopenia associated with myelodysplastic syndrome, and ten weeks before this admission, percutaneous transluminal coronary angioplasty with implantation of drug-eluting stents was performed for non-ST-segment elevation acute coronary syndrome. Platelets in myelodysplastic syndromes are dysfunctional, which exacerbates bleeding from thrombocytopenia, and the management of atherosclerotic cardiovascular disease in these patients is challenging.

Long-term follow-up for up to 5 years on the risk of leukaemic progression in thrombocytopenic patients with lower-risk myelodysplastic syndromes treated with romiplostim or placebo in a randomised double-blind trial

BACKGROUND

Treatment options for thrombocytopenia in myelodysplastic syndromes are scarce. As described previously in a randomised phase 2 study (n=250), 58 weeks of romiplostim treatment in patients with International Prognostic Scoring System (IPSS)-defined lower-risk (low-risk or intermediate-1 risk) myelodysplastic syndromes led to reduced platelet transfusions (p<0·0001) and increased International Working Group-defined haematological improvement-platelet rates (p<0·0001) versus placebo. However, the study drug was discontinued because of the potential risk for progression to or incorrect diagnosis or treatment for acute myeloid leukaemia, based on an acute myeloid leukaemia interim hazard ratio (HR) of 2·5; the subsequent 58-week acute myeloid leukaemia HR was 1·2 (95% CI 0·4-3·8).

METHODS

This study is a 5-year follow-up of a phase 2, multicentre, double-blind trial of romiplostim treatment in patients with lower-risk myelodysplastic syndromes. Eligible patients were recruited at 109 centres in North America, Europe, Russia, and Australia, were aged 18-90 years, and had platelets of 20 × 10⁹ per L or less with or without a history of bleeding or 50 × 10⁹ platelets per L or less with a history of bleeding. Patients were randomly assigned by interactive voice response system with stratification by baseline platelet count (≥20 × 10⁹ per L or <20 × 10⁹ per L) and IPSS risk (low or intermediate-1) to receive either placebo or 750 μg romiplostim subcutaneously once per week for 58 weeks. The primary outcomes for this long-term follow-up were survival and progression to acute myeloid leukaemia. Progression to acute myeloid leukaemia was defined as either 20% blasts or more after 4 weeks from romiplostim discontinuation; as per pathology; or by initiation of antileukaemia treatment. The primary outcome was assessed per protocol in all patients with available data. This study is registered with ClinicalTrials.gov, NCT00614523.

FINDINGS

Patients were recruited from July 21, 2008, to Dec 16, 2010. 167 patients were assigned to receive romiplostim treatment and 83 were assigned to receive placebo. 210 (84%) of 250 patients entered the 5-year long-term follow-up (139 patients in the romiplostim group and 83 in the placebo group). At the end of follow-up, proportions of patients with acute myeloid leukaemia (20 [12%] of 167 in the romiplostim group vs nine [11%] of 83 in the placebo group; HR 1·06 [95% CI 0·48-2·33]; p=0·88) and proportions who died (93 [56%] vs 54 [54%]; HR 1·03 [0·72-1·47]; p=0·89) were not significantly different between the two groups.

INTERPRETATION

Following the decision to stop the study drug, 5-year long-term follow-up HRs for transformation to acute myeloid leukaemia and HRs for death did not differ between patients treated with romiplostim and those treated with placebo, indicating that use of romiplostim is probably not associated with any increased risk of acute myeloid leukaemia or death, despite initial concerns.

FUNDING

Amgen Inc.

Myelodysplastic Syndromes: Diagnosis and Treatment

In the past few years, new biological insights into the myelodysplastic syndromes (MDS) resulting from molecular genetic analysis have improved pathologic understanding, but treatment advances have not kept pace. More than 40 genes are now known to be recurrently mutated in MDS. However, because most of these genes encode spliceosome components, chromatic remodeling factors, epigenetic pattern modulators, or transcription factors rather than more easily inhibited activated tyrosine kinases, there are as of yet few narrowly targeted therapies available for MDS. Three drugs--azacitidine, decitabine, and lenalidomide--were approved by the US Food and Drug Administration for MDS indications a decade ago, and these agents can improve hematopoiesis, delay disease progression, and improve survival and quality of life for a subset of patients. However, only a few patients with MDS respond to these agents, and their benefit is temporary. The only potentially curative therapy for MDS is allogeneic hematopoietic stem cell transplant, but owing to the advanced age of many patients with MDS and the frequency of serious comorbid conditions, less than 10% of patients currently undergo stem cell transplant. This narrative review summarizes the current understanding of MDS and treatment options for these challenging disorders.

Results of a randomized, double-blind study of romiplostim versus placebo in patients with low/intermediate-1-risk myelodysplastic syndrome and thrombocytopenia

BACKGROUND

Thrombocytopenia in patients with myelodysplastic syndrome (MDS) is associated with shortened survival and an increased risk of evolution to acute myeloid leukemia (AML). In this study, the authors evaluated the efficacy of romiplostim in patients who had thrombocytopenia with low-risk/intermediate-1–risk MDS.

METHODS

Patients who had thrombocytopenia with low-risk/intermediate-1–risk MDS (N = 250) were randomized 2:1 to receive romiplostim or placebo weekly for 58 weeks.

RESULTS

The primary endpoint— the number of clinically significant bleeding events (CSBEs) per patient—had a hazard ratio for romiplostim:placebo of 0.83 (95% confidence interval, 0.66-1.05; P = .13). CSBEs were reduced significantly in the romiplostim group for patients who had baseline platelet counts ≥20 × 10⁹/L (P < .0001). For patients who had baseline platelet counts <20 × 10⁹/L, there was no difference in the number of CSBEs, but the platelet transfusion rates were higher in the placebo group (P < .0001), which may have affected the overall CSBE results in this group with severe thrombocytopenia. The incidence of bleeding events was reduced significantly in the romiplostim group (relative risk, 0.92), as were protocol-defined platelet transfusions (relative risk, 0.77). Platelet response rates according to 2006 International Working Group criteria were higher for the group that received romiplostim (odds ratio, 15.6). On the basis of interim data, an independent data monitoring committee advised halting study drug because of concerns regarding excess blasts and AML rates with romiplostim (interim hazard ratio, 2.51). At 58 weeks, the AML rates were 6% in the romiplostim group and 4.9% in the placebo group (hazard ratio, 1.20; 95% confidence interval, 0.38-3.84), and the overall survival rates were similar.

CONCLUSIONS

Romiplostim treatment in patients with low-risk/intermediate-1–risk MDS increased platelet counts and decreased the number of bleeding events and platelet transfusions. Although study drug was discontinued because of an initial concern of AML risk, survival and AML rates were similar with romiplostim and placebo.

Use of whole blood platelet lumi-aggregometry to optimize anti-platelet therapy in patients with chronic myeloproliferative disorders

Twenty-seven patients with chronic myeloproliferative disorders and in vitro evidence of platelet hyperactivity on whole blood platelet lumi-aggregometry were commenced on anti-platelet therapy comprising aspirin, clopidogrel, and/or odorless garlic and the studies were repeated to assess the efficacy of the therapeutic agent(s). Only 8 patients showed clear evidence of anti-platelet effect while receiving the standard low-dose (100 mg/day) aspirin therapy. Thirteen patients required a higher dosage of aspirin and/or an additional anti-platelet agent to achieve therapeutic adequacy. Lumi-aggregometry also proved useful to optimize therapy in the 6 patients who received clopidogrel or odorless garlic because of aspirin intolerance.