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

Eltrombopag for the Treatment of Severe Inherited Thrombocytopenia

Inherited thrombocytopenias correspond to a group of hereditary disorders characterized by a reduced platelet count, platelet dysfunction, and a family history of thrombocytopenia. It is commonly associated with mucocutaneous bleeding. Thrombocytopenia results from mutations in genes involved in megakaryocyte differentiation, platelet formation, and clearance. Here we report on a patient presenting with severe syndromic inherited thrombocytopenia manifesting as spontaneous mucocutaneous bleeds, requiring frequent platelet transfusions. Thrombocytopenia was explained by the presence of 4 mutations in 3 hematopoietic transcription factor genes: FLI1, RUNX1, and ETV6. The patient was successfully treated with high-dose eltrombopag at 150 mg/day, an orally available non-peptide thrombopoietin receptor agonist. Since the start of treatment 23 months ago, the manifestations of bleeding have resolved, and no platelet transfusions or corticosteroids have been required. The patient has no clinical or laboratory evidence of myeloid malignancy so far.

Thrombopoietin-receptor agonists in perioperative treatment of patients with chronic liver disease

Thrombocytopenia is a multifactorial disorder that is common in patients with chronic liver disease (CLD), leading to challenging perioperative planning. As thrombocytopenia in CLD is associated with thrombopoietin (TPO) deficiency, the use of TPO-receptor agonists (TPO-RAs) to increase platelet counts is a promising approach. This has led to the development of various TPO-RAs, including romiplostim, eltrombopag, avatrombopag, and lusutrombopag. Of these, only avatrombopag and lusutrombopag are approved by the United States Food and Drug Administration for the perioperative treatment of thrombocytopenia in patients with CLD. Platelet transfusion is commonly used for the clinical management of thrombocytopenia in patients with CLD undergoing invasive procedures. However, the limitations and possible risks of transfusion, including short duration of efficacy, development of antiplatelet antibodies, risk of infections and such complications as transfusion-related acute lung injury or circulatory overload, and possibility of refractoriness, limit its use. Moreover, there is no consensus among guidelines as to the platelet count at which transfusions are indicated. Results from studies using TPO-RAs perioperatively in patients with thrombocytopenia and CLD are promising and provide an alternative to platelet transfusions in the pre- and post-operative setting. These TPO-RAs are the subject of this review, with focus on their use in the perioperative setting in patients with thrombocytopenia, associated supporting clinical trials, efficacy and safety data, and their use with respect to platelet transfusions.

The thrombopoietin mimetic JNJ-26366821 increases megakaryopoiesis without affecting malignant myeloid proliferation

Thrombocytopenia remains a challenge in myeloid malignancies, needing safer and more effective therapies. JNJ-26366821, a pegylated synthetic peptide thrombopoietin (TPO) mimetic not homologous to endogenous TPO, has an in-vitro EC50 of 0.2 ng/mL for the TPO receptor and dose dependently elevates platelets in volunteers. We demonstrate that JNJ-26366821 increases megakaryocytic differentiation and megakaryocytic colony formation in healthy controls and samples from myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). JNJ-26366821 had no effect on proliferation of malignant myeloid cell lines at doses up to 1000 ng/mL and malignant patient-derived mononuclear cells showed no increased cell growth or leukemic colony formation capacity at concentrations between 0.2 ng/mL and 10 ng/mL. Furthermore, JNJ-26366821 did not enhance in-vivo engraftment of leukemic cells in an AML xenotransplantation murine model. Our results show that JNJ-26366821 stimulates megakaryopoiesis without causing proliferation of the malignant myeloid clones in MDS/AML and provides the rationale for clinical testing of JNJ-26366821 in myeloid malignancies.

Myelodysplastic syndromes: a review of therapeutic progress over the past 10 years

INTRODUCTION

Myelodysplastic syndromes (MDS) represent a range of bone marrow disorders, with patients affected by cytopenias and risk of progression to AML. There are limited therapeutic options available for patients, including hypomethylating agents (azacitidine/decitabine), growth factor support, lenalidomide, and allogeneic stem cell transplant.

AREAS COVERED

This review provides an overview of the progress made over the past decade for emerging therapies for lower- and higher-risk MDS (MDS-HR). We also cover advances in prognostication, supportive care, and use of allogeneic SCT in MDS.

EXPERT OPINION

While there have been no FDA-approved therapies for MDS in the past decade, we anticipate the approval of luspatercept based on results from the MEDALIST trial for patients with lower-risk MDS (MDS-LR) and ringed sideroblasts who have failed or are ineligible for erythropoiesis stimulating agents (ESAs). With growing knowledge of the biologic and molecular mechanisms underlying MDS, it is anticipated that new therapies will be approved in the coming years.

A sequential two-stage dose escalation study of eltrombopag in patients with myelodysplastic syndrome and thrombocytopenia after hypomethylating agent failure

Thrombocytopenia occurs frequently in patients with myelodysplastic syndromes (MDS), and the survival of patients after failure of hypomethylating agents (HMAs) is poor. We conducted a trial of eltrombopag in patients with MDS, MDS/myeloproliferative neoplasm (MPN) or acute myeloid leukemia (AML) with 20-30% myeloblasts after HMA failure and mean baseline platelet count ≤ 50 × 10⁹/L. Eltrombopag was escalated from 50 mg daily up to 200 mg daily. The primary objective was to determine the maximally tolerated dose (MTD). 37 patients were enrolled, and MTD was not reached. Responses were observed in 9 patients (24%), 2 achieving marrow CR with hematologic improvement (HI), 1 marrow CR without HI, and 6 HI. Median overall survival was 7.5 months. Eltrombopag was well-tolerated and yielded modest responses in heavily treated, predominantly higher-risk MDS patients after HMA failure. Future studies should focus on determining characteristics that predict response.

[Myelodysplastic syndromes]

Myelodysplastic syndromes (MDS)-previously called "preleukemias"-are clonal diseases of the pluripotent hematopoietic stem cell. Their hallmark is peripheral cytopenias. Early forms are characterized by dysplasia of mature cells in the peripheral blood or erythropoiesis, granulopoiesis or megakaryocytes in the bone marrow, and later stages tend to accumulate blasts. About 30% transform into acute myeloid leukemia. MDS are diseases of the elderly and are prognostically divided into lower and higher risk diseases. Median survival times vary accordingly between 6 months and 10 years. Chromosomal abnormalities are identified in 50% of patients, and single or multiple gene mutations occur in 80%. They are the driving force leading to abnormalities in differentiation and to the accumulation of blasts in the bone marrow. Therapeutic options include supportive care, erythropoiesis-stimulating agents, demethylating agents, and allogeneic stem cell transplantation.

Lowering the boom on lower-risk myelodysplastic syndromes

Lower-risk myelodysplastic syndromes are defined using prognostic scoring systems that incorporate data on bone marrow blast percentage, degree and numbers of cytopenias, and cytogenetic abnormalities. Increasingly, these are incorporating molecular abnormalities to further refine risk. Therapy is geared toward predominating cytopenias, with erythropoiesis-stimulating agents luspatercept and lenalidomide used to ameliorate anemia, romiplostim and eltrombopag tackling thrombocytopenia, and hypomethylating agents and antithymocyte globulin palliating pancytopenia. Newer agents on the horizon are abrogating the downstream sequelae of specific molecular mutations. One challenge for the future is in further modifying response criteria to align with improvements that are clinically meaningful to patients.

Mechanisms and therapeutic prospects of thrombopoietin receptor agonists

The second-generation thrombopoietin (TPO) receptor agonists eltrombopag and romiplostim are potent activators of megakaryopoiesis and represent a growing treatment option for patients with thrombocytopenic hematological disorders. Both TPO receptor agonists have been approved worldwide for the treatment of children and adults with chronic immune thrombocytopenia. In the EU and USA, eltrombopag is approved for the treatment of patients with severe aplastic anemia who have had an insufficient response to immunosuppressive therapy and in the USA for the first-line treatment of severe aplastic anemia in combination with immunosuppressive therapy. Eltrombopag has also shown efficacy in several other disease settings, for example, chemotherapy-induced thrombocytopenia, selected inherited thrombocytopenias, and myelodysplastic syndromes. While both TPO receptor agonists stimulate TPO receptor signaling and enhance megakaryopoiesis, their vastly different biochemical structures bestow upon them markedly different molecular and functional properties. Here, we review and discuss results from preclinical and clinical studies on the functional and molecular mechanisms of action of this new class of drug.

Avatrombopag for the treatment of immune thrombocytopenia and thrombocytopenia of chronic liver disease

Avatrombopag is an orally-administered small molecule thrombopoietin receptor agonist. It was the third thrombopoietin receptor agonist approved for the treatment of immune thrombocytopenia and the first approved to treat periprocedural thrombocytopenia in patients with chronic liver disease (thereby providing an alternative to blood transfusions for these patients). Unlike eltrombopag, avatrombopag does not require a 4 hr food-restricted window around its use and it has not been associated with hepatotoxicity in ITP patients or portal vein thrombosis in patients with chronic liver disease. In ITP patients it can often be dosed less frequently than once daily. It is overall well-tolerated with a side-effect profile similar to placebo in randomized clinical trials. This article will review the clinical development, efficacy, safety, and pharmacology of avatrombopag for use in patients with ITP and thrombocytopenia of chronic liver disease.

Novel therapies in low- and high-risk myelodysplastic syndrome

Introduction: Myelodysplastic syndromes (MDS) comprise a heterogeneous group of myeloid neoplasms with diverse clinical courses. The revised version of the international prognostic scoring system (IPSS-R) provides risk stratification into 5 different groups. Areas covered: For lower-risk patients, red blood cell transfusions and iron chelation are the backbone of supportive care. In addition, erythropoiesis-stimulating agents (ESA) are used to ameliorate anemia. Lenalidomide is approved for the treatment of lower-risk patients with del(5q) who are transfusion-dependent. Patients with higher-risk disease should be offered allogeneic stem cell transplantation whenever possible. If they are unfit for transplantation or an appropriate donor cannot be found, hypomethylating agents may be used. Expert opinion: New therapeutic options for lower-risk patients include thrombopoietin analogues, the TGF-beta family ligand trapping drug Luspatercept, and the telomerase inhibitor Imetelstat. Combinations of hypomethylating agents (HMA) with other compounds, and inhibitors of bcl2, such as venetoclax are being developed for higher-risk patients. Finally, hypomethylating agents in combination with donor lymphocytes may lead to long-term remission following molecular or hematological relapse after allogeneic SCT.

Eltrombopag for the treatment of inherited thrombocytopenias: a phase II clinical trial

Patients with inherited thrombocytopenias often require platelet transfusions to raise their platelet count before surgery or other invasive procedures; moreover, subjects with clinically significant spontaneous bleeding may benefit from an enduring improvement of thrombocytopenia. The hypothesis that thrombopoietin-mimetics can increase platelet count in inherited thrombocytopenias is appealing, but evidence is scarce. We conducted a prospective, phase II clinical trial to investigate the efficacy of the oral thrombopoietin-mimetic eltrombopag in different forms of inherited thrombocytopenia. We enrolled 24 patients affected by MYH9-related disease, ANKRD26-related thrombocytopenia, X-linked thrombocytopenia/ Wiskott-Aldrich syndrome, monoallelic Bernard-Soulier syndrome, or ITGB3-related thrombocytopenia. The average pre-treatment platelet count was 40.4 ×10⁹/L. Patients received a 3- to 6-week course of eltrombopag in a dose-escalated manner. Of 23 patients evaluable for response, 11 (47.8%) achieved a major response (platelet count >100 ×10⁹/L), ten (43.5%) had a minor response (platelet count at least twice the baseline value), and two patients (8.7%) did not respond. The average increase of platelet count compared to baseline was 64.5 ×10⁹/L (P<0.001). Four patients with clinically significant spontaneous bleeding entered a program of long-term eltrombopag administration (16 additional weeks): all of them obtained remission of mucosal hemorrhages, with the remission persisting throughout the treatment period. Treatment was globally well tolerated: five patients reported mild adverse events and one patient a moderate adverse event. In conclusion, eltrombopag was safe and effective in increasing platelet count and reducing bleeding symptoms in different forms of inherited thrombocytopenia. Despite these encouraging results, caution is recommended when using thrombopoietinmimetics in inherited thrombocytopenias predisposing to leukemia. ClinicalTrials.gov identifier: NCT02422394.

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.

[Management of myelodysplastic syndromes in 2019: An update]

Myelodysplastic syndromes are a heterogeneous group of clonal myeloid disorders characterized by peripheral cytopenias and an increased risk of progression to acute myeloid leukemia. Inflammatory, auto-immune or syndromic symptoms can make the diagnosis difficult. Diagnosis is currently based on bone marrow cytology but cytogenetics and molecular features are currently overpassing their initial prognostic function (allowing early diagnosis and prediction of therapeutic response). The prognostic classification is based on the Revised International Prognostic Scoring System, which also provides guidance for therapeutic management. The treatment of low-risk myelodysplastic syndromes is based on the correction of cytopenias (erythropoiesis stimulating agents, transfusions, lenalidomide, etc.), whereas in high-risk group, the goal is the control of the leukemic clone (hypomethylating agents, allograft of hematopoietic stem cell transplantation). Other molecules are used to manage complications of cytopenias or transfusion (anti-infectious prophylaxis and treatments, martial chelation). New molecules are being studied with some interesting results (luspatercept, venetoclax). This article aims to provide an update on the knowledge that an internist should know for the practical management of myelodysplastic syndromes in 2019.

Eltrombopag treatment during induction chemotherapy for acute myeloid leukaemia: a randomised, double-blind, phase 2 study

BACKGROUND

Patients with acute myeloid leukaemia frequently have thrombocytopenia during induction chemotherapy. Eltrombopag, an oral thrombopoietin receptor agonist, stimulates platelet production by a similar mechanism to endogenous thrombopoietin. This study investigated safety and efficacy of eltrombopag versus placebo during anthracycline-based induction treatment of patients with acute myeloid leukaemia.

METHODS

In this randomised, double-blind, phase 2 study, treatment-naive patients were recruited from clinical centres across 10 countries (Australia, Belgium, Canada, Greece, Hungary, Israel, South Korea, Poland, Russia, and the USA). Patients with acute myeloid leukaemia of any subtype except M3 and M7 were stratified by antecedent malignant haematological disorder (yes or no) and age (18-60 years or >60 years) and were then randomly assigned (1:1) using an automated interactive voice-response system randomisation schedule. Investigators and patients were blinded to study treatment. Starting on day 4, patients received standard induction chemotherapy (daunorubicin bolus intravenous infusion on days 1-3 [90 mg/m² for patients aged 18-60 years or 60 mg/m² for patients aged >60 years], plus cytarabine continuous intravenous infusion on days 1-7 [100 mg/m²]), with eltrombopag 200 mg (100 mg for east Asians) or placebo once daily, until platelet counts were 200 × 10⁹/L or higher, until remission, or after 42 days from the start of induction chemotherapy. The primary objective of the study was safety and tolerability assessed by adverse events, changes in left ventricular ejection fraction (LVEF), and clinical laboratory parameters in all treated patients. This study has been completed and is registered with ClinicalTrials.gov, number NCT01890746.

FINDINGS

Between Sept 7, 2013, and Jan 30, 2015, 149 patients were assessed for eligibility and 148 were then randomly assigned to receive eltrombopag (n=74) and placebo (n=74). Groups were matched in mean (SD) age (56·7 years [12·3] in the eltrombopag group vs 56·6 years [11·6] in the placebo group), mean (SD) initial platelet count (59·5 × 10⁹/L [43·3] vs 63·7 × 10⁹/L [48·0]), and poor-risk karyotype (16 [22%] of 74 patients in both groups). The most common grade 3-4 adverse events (≥10% in either group) were febrile neutropenia (31 [42%] vs 28 [39%]), decreased white blood cell count (8 [11%] vs 5 [7%]), and hypophosphataemia (3 [4%] vs 9 [13%]). Serious adverse events occurred in 24 (32%) patients in the eltrombopag group compared with 14 (20%) patients in the placebo group. 39 (53%) patients in the eltrombopag group died versus 29 (41%) patients in the placebo group. Thromboembolic events (5 [7%] vs 4 [6%]) and mean (SD) change in LVEF (-2·5% [7·8] vs -4·3% [8·5]) were similar.

INTERPRETATION

Data from this trial do not support combining eltrombopag with induction chemotherapy in patients with acute myeloid leukaemia.

FUNDING

Novartis Pharma AG.

Current and Future Treatment Options for Myelodysplastic Syndromes: More Than Hypomethylating Agents and Lenalidomide?

Myelodysplastic syndromes are a heterogeneous group of bone marrow disorders that result in cytopenias and a propensity to develop secondary leukemia. While allogeneic transplantation still remains the only potential curative treatment option, it can only be offered to a limited number of patients. For the majority, who are not transplant candidates, treatment strategies cover iron chelation, growth factors, lenalidomide, and hypomethylating agents to improve cytopenia and potentially delay disease progression. These limited options underpin the urgent need for more translational research-based clinical trials in well-defined subgroups of patients with myelodysplastic syndromes. Indeed, myelodysplastic syndromes are a moving target with maximum innovation in the understanding of the complex molecular pathways during the last decade. Compared with other hematological diseases such as myeloma, this has unfortunately not yet translated into approval of novel treatment options. Given the current developments in the field, we are optimistic that recent frustrations will be overcome shortly and this will pave the way for exciting opportunities, especially for patients not responding to first-line therapeutic options.

Azacitidine with or without eltrombopag for first-line treatment of intermediate- or high-risk MDS with thrombocytopenia

Azacitidine treatment of myelodysplastic syndromes (MDSs) generally exacerbates thrombocytopenia during the first treatment cycles. A Study of Eltrombopag in Myelodysplastic Syndromes Receiving Azacitidine (SUPPORT), a phase 3, randomized, double-blind, placebo-controlled study, investigated the platelet supportive effects of eltrombopag given concomitantly with azacitidine. International Prognostic Scoring System intermediate-1, intermediate-2, or high-risk MDS patients with baseline platelets <75 × 10⁹/L were randomized 1:1 to eltrombopag (start, 200 mg/d [East Asians, 100 mg/d], maximum, 300 mg/d [East Asians, 150 mg/d]) or placebo, plus azacitidine (75 mg/m² subcutaneously once daily for 7 days every 28 days). The primary end point was the proportion of patients platelet transfusion-free during cycles 1 through 4 of azacitidine therapy. Based on planned interim analyses, an independent data monitoring committee recommended stopping the study prematurely because efficacy outcomes crossed the predefined futility threshold and for safety reasons. At termination, 28/179 (16%) eltrombopag and 55/177 (31%) placebo patients met the primary end point. Overall response (International Working Group criteria; complete, marrow, or partial response) occurred in 20% and 35% of eltrombopag and placebo patients, respectively, by investigator assessment. There was no difference in hematologic improvement in any cell lineage between the 2 arms. There was no improvement in overall or progression-free survival. Adverse events with ≥10% occurrence in the eltrombopag vs placebo arm were febrile neutropenia and diarrhea. Compared with azacitidine alone, eltrombopag plus azacitidine worsened platelet recovery, with lower response rates and a trend toward increased progression to acute myeloid leukemia. This trial was registered at www.clinicaltrials.gov as #NCT02158936.

Thrombopoietin receptor agonists in hereditary thrombocytopenias

Hereditary thrombocytopenias (HTPs) constitute a heterogeneous group of diseases characterized by a reduction in platelet count and a potential bleeding risk. As a result of advances in diagnostic methods, HTPs are increasingly being identified, and appear to be less rare than previously thought. Most HTPs do not have effective treatments, except for platelet transfusion when bleeding occurs and in preparation for procedures associated with a risk of bleeding. Preliminary clinical evidence suggests that thrombopoietin receptor agonists (TPO-RAs) with an established use in the treatment of certain acquired thrombocytopenias are well tolerated and provide clinical benefits in patients with some forms of HTP. These drugs may therefore be considered for the treatment of HTPs in clinical practice. However, caution and close monitoring are recommended, owing to the absence of long-term safety data and the potential risks posed by prolonged bone marrow stimulation in certain HTPs. In this review, we summarize the available clinical data on TPO-RAs in the treatment of HTPs, and discuss their use in patients with these disorders. We believe that TPO-RAs will play a major role in the treatment of HTPs, particularly myosin heavy chain 9-related disease, Wiskott-Aldrich syndrome, X-linked thrombocytopenia, and thrombocytopenia caused by THPO mutations.

CC-486 (oral azacitidine) in patients with myelodysplastic syndromes with pretreatment thrombocytopenia

Thrombocytopenia is among the strongest predictors of decreased survival for patients with myelodysplastic syndromes (MDS) across all prognostic risk groups. The safety and efficacy of CC-486 (oral azacitidine) was investigated in early-phase studies; we assessed clinical outcomes among subgroups of MDS patients from these studies, defined by presence or lack of pretreatment thrombocytopenia (≤75 × 10⁹/L platelet count). Patients received CC-486 300 mg once-daily for 14 or 21 days of repeated 28-day cycles. Overall, 81 patients with MDS, median age 72 years, comprised the Low Platelets (n = 45) and High Platelets (n = 36) cohorts. Pretreatment median platelet counts were 34 × 10⁹/L and 198 × 10⁹/L, respectively. Grade 3-4 bleeding events occurred in 2 patients in the Low Platelets and 1 patient in the High Platelets groups; events resolved without sequelae. Treatment-related mortality was reported for 7 patients, 5 of whom had pretreatment platelet values <25 × 10⁹/L. Overall response rates were 38% and 46% in the Low Platelets and High Platelets groups, respectively. Five thrombocytopenic patients attained complete remission and 9 attained platelet hematologic improvement. In both cohorts, platelet counts dropped during the first CC-486 treatment cycle, then increased thereafter. Extended CC-486 dosing was generally well tolerated and induced hematologic responses in these patients regardless of pretreatment thrombocytopenia.

Thrombocytopenia in Patients with Myelodysplastic Syndromes: Still an Unsolved Problem

The myelodysplastic syndromes (MDS) are a group of clonal bone marrow (BM) stem cell disorders, characterized by ineffective hematopoiesis, peripheral cytopenias, and hematologic cellular dysfunction, as well as potential transformation to acute leukemia. Thrombocytopenia is common in MDS and is associated with bleeding complications, occasionally life-threatening. Low platelet count (PLT), as well declining PLT also serves as a prognostic marker. Understanding thrombopoiesis led to the cloning of thrombopoietin, resulting in the development of platelet stimulating agents, thrombomimetics, romiplostim and eltrombopag. Both agents have been shown to increase PLT, decrease the need for platelet transfusions and reduce the number of bleeding episodes, with a reasonable tolerance. They are already approved for immune thrombocytopenia and thrombocytopenia related to liver disease. Romiplostim and eltrombopag have proven efficacy in lower- and higher-risk MDS with thrombocytopenia, as monotherapy, as well as a part of a combination, either with lenalidomide, and mainly combined with hypomethylating agents. However, safety concerns have been raised: while several trials have been completed with no evidence of disease progression, others have been early terminated due to an increased number of BM blasts and possible leukemic transformation in treated-patients. The jury is still out regarding this safety concern, although recent publications are more encouraging.

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.

Recent advances in the cellular and molecular understanding of myelodysplastic syndromes: implications for new therapeutic approaches

It has been more than 10 years since any new disease-modifying therapies have received regulatory approval for indications related to myelodysplastic syndromes (MDS). Advances in our collective biological understanding of MDS in the last decade, however, have made it possible to hope that effective therapeutics can be designed to improve MDS-associated cytopenias and patients' quality of life, and perhaps even delay clonal progression and extend survival. Classes of MDS-associated mutations and disordered biological pathways targeted by developmental therapeutics include the following: aberrant messenger RNA splicing, neomorphic enzymes in the citric acid cycle with oncogenic activity, overactivated tyrosine and serine-threonine kinases, epigenetic and chromatin remodeling alterations, abnormal telomere dynamics, and failed protection of DNA integrity. At present, treatments for MDS are usually administered as sequential monotherapy, but there is a trend toward clinical trials of combination therapies-in which new agents are added to a DNA hypomethylating agent backbone-for both upfront treatment and the treatment of relapsed/refractory disease. Agents in clinical trials for subsets of MDS include luspatercept, antibodies targeting CD33, isocitrate dehydrogenase inhibitors, deacetylase inhibitors, venetoclax, and immunotherapies designed to overcome immune checkpoint inhibition. These biologically based therapeutics, as well as the encouraging precedent of 7 new approvals by the US Food and Drug Administration in 2017 for the treatment of acute leukemia, offer the prospect that 10 more years will not elapse before another new therapy is approved for MDS.

Peptibodies: An elegant solution for a long-standing problem

Chimeric proteins composed of a biologically active peptide and a fragment crystallizable (Fc) domain of immunoglobulin G (IgG) are known as peptibodies. They present an extended half-life due to neonatal Fc receptor (FcRn) salvage pathway, a decreased renal clearance rate owing to its increased size (≈70 kDa) and, depending on the peptide used in the design of the peptibody, an active-targeting moiety. Also, the peptides therapeutic activity is boosted by the number of peptides in the fusion protein (at least two peptides) and to some peptides' alterations. Peptibodies are mainly obtained through recombinant DNA technology. However, to improve peptide properties, "unnatural" changes have been introduced to the original peptides' sequence, for instance, the incorporation of D- or non-natural amino acid residues or even cyclization thus, limiting the application of genetic engineering in the production of peptibodies, since these peptides must be obtained via chemical synthesis. This constrains prompted the development of new methods for conjugation of peptides to Fc domains. Another challenge, subject of intense research, relates to the large-scale production of such peptibodies using these new techniques, which can be minimized by their proved value. To date, two peptibodies, romiplostim and dulaglutide, have been approved and stay as the standard of care in their areas of action. Furthermore, a considerable number of peptibodies are currently in preclinical and clinical development.

Eltrombopag for advanced myelodysplastic syndromes or acute myeloid leukaemia and severe thrombocytopenia (ASPIRE): a randomised, placebo-controlled, phase 2 trial

BACKGROUND

Thrombocytopenia is a life-threatening complication in patients with advanced myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML). In this study (ASPIRE), we aimed to assess eltrombopag, an oral thrombopoietin receptor agonist, for thrombocytopenia (grade 4) treatment in adult patients with advanced MDS or AML.

METHODS

ASPIRE consisted of an open-label, double-blind phase for 8 weeks and a randomised, double-blind phase (parts 1 and 2, reported here) for 12 weeks, and an open-label extension (part 3). Eligible patients were men and women aged 18 years or older, with intermediate-2 or high-risk MDS or AML, with bone marrow blasts of 50% or less, and had either grade 4 thrombocytopenia due to bone marrow insufficiency (platelet counts <25 × 10⁹ per L) or grade 4 thrombocytopenia before platelet transfusion, with 25 × 10⁹ platelets per L or greater after transfusion. Additionally, eligible patients had at least one of the following within the screening period of 4 weeks: platelet transfusion, symptomatic bleeding, or platelet count of less than 10 × 10⁹ per L. During part 1, patients received eltrombopag, and dose-escalation criteria for part 2 were determined. In part 2, we randomly allocated patients 2:1 using an interactive voice-response system to eltrombopag or placebo, stratified by baseline platelet count (<10 × 10⁹ platelets per L vs ≥10 × 10⁹ platelets per L) and disease (MDS vs AML). In parts 1 and 2, patients received supportive standard of care and initiated eltrombopag or placebo at 100 mg per day (50 mg per day for patients of east-Asian heritage) to a maximum of 300 mg per day (150 mg per day for patients of east-Asian heritage). The part 2 primary objective was assessed by a composite primary endpoint of clinically relevant thrombocytopenic events (CRTE) during weeks 5-12, defined as one of the following events, either alone or in combination: grade 3 or worse haemorrhagic adverse events; platelet counts of less than 10 × 10⁹ per L; or platelet transfusions. Efficacy analyses were based on intention to treat; clinically meaningful efficacy was defined as 30% absolute difference between groups. This trial is registered with ClinicalTrials.gov, number NCT01440374.

FINDINGS

In part 1, 17 patients received eltrombopag and 11 patients completed treatment; four experienced significantly increased platelet counts, and ten had reduced platelet transfusion requirements. In part 2 we randomly allocated 145 patients to receive supportive care plus eltrombopag (n=98) or placebo (n=47); similar proportions had MDS (50 [51%] patients to eltrombopag, 22 (47%) patients to placebo) or AML (48 [49%] patients to eltrombopag, 25 [53%] patients to placebo). Average weekly CRTE proportions from weeks 5-12 were significantly lower with eltrombopag (54% [95% CI 43-64]) than with placebo (69% [57-80], odds ratio [OR] 0·20, 95% CI 0·05-0·87; p=0·032) although the difference between treatment groups was less than 30%. The most common grade 3 and grade 4 adverse events were fatigue (six [6%] in the eltrombopag group and one [2%] in the placebo group), hypokalaemia (six [6%] and two [4%]), pneumonia (five [5%] and five [11%]), and febrile neutropenia (five [5%] and six [13%]). Serious adverse events were reported in 56 (58%) eltrombopag-treated patients and 32 (68%) placebo-treated patients. Seven eltrombopag recipients and two placebo recipients had serious adverse events that were suspected to be study drug-related (eltrombopag: acute kidney injury, arterial thrombosis, bone pain, diarrhoea, myocardial infarction, pyrexia, retinal vein occlusion, n=1 each; placebo: vomiting, white blood cell count increased, n=1 each). Two eltrombopag recipients (arterial thrombosis n=1; myocardial infarction n=1) and no placebo recipients experienced fatal serious adverse events suspected to be study drug-related.

INTERPRETATION

No new safety concerns were noted with eltrombopag and the trial met the primary objective of a reduction in CRTEs; eltrombopag might be a treatment option for thrombocytopenic patients with AML or MDS who are ineligible for other treatment and who are not receiving disease-modifying treatment.

FUNDING

Novartis Pharma AG.

Current treatment algorithm for the management of lower-risk MDS

Lower risk myelodysplastic syndromes (MDS), defined as MDS with a Revised International Prognostic Scoring System score ≤3.5 points, will remain a challenging entity in 2018. Supportive care continues to be the linchpin of treatment, although the options to reduce transfusion needs are broadening. To achieve red blood cell transfusion independence in non-del(5q) patients, erythropoiesis-stimulating agents remain a mainstay of therapy as long as endogenous erythropoietin levels are <500 U/L (and preferably <200 U/L). Experimental strategies for patients ineligible for erythropoiesis-stimulating agents or relapsing after gaining transfusion independence include immunosuppressive agents, transforming growth factor β inhibitors, and lenalidomide. All these alternatives have shown reasonable response rates in selected patient populations with lower risk MDS. Patients with del(5q) disease can derive long-term benefit from lenalidomide, and some patients remain transfusion free for extended periods even after discontinuation of the drug. In rare cases in which thrombocytopenia is the main clinical problem leading to clinically significant bleeding events, thrombopoietin receptor analogues may alleviate bleeding, increase platelet counts, and rarely lead to trilineage responses. It seems prudent to use these drugs only in patients with confirmed bone marrow blast counts <5%. Allogeneic stem cell transplantation is reasonable for patients with high molecular risk of progression and those failing several lines of treatment with signs of progression toward higher-risk MDS.

Thrombopoietin mimetics for patients with myelodysplastic syndromes

BACKGROUND

Myelodysplastic syndrome (MDS) is one of the most frequent haematologic malignancies of the elderly population and characterised by progenitor cell dysplasia with ineffective haematopoiesis and a high rate of transformation to acute myeloid leukaemia (AML). Thrombocytopenia represents a common problem for patients with MDS. ranging from mild to serious bleeding events and death. To manage thrombocytopenia, the current standard treatment includes platelet transfusion, unfortunately leading to a range of side effects. Thrombopoietin (TPO) mimetics represent an alternative treatment option for MDS patients with thrombocytopenia. However, it remains unclear, whether TPO mimetics influence the increase of blast cells and therefore to premature progression to AML.

OBJECTIVES

To evaluate the efficacy and safety of thrombopoietin (TPO) mimetics for patients with MDS.

SEARCH METHODS

We searched for randomised controlled trials in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (January 2000 to August 2017), trials registries (ISRCTN, EU clinical trials register and clinicaltrials.gov) and conference proceedings. We did not apply any language restrictions. Two review authors independently screened search results, disagreements were solved by discussion.

SELECTION CRITERIA

We included randomised controlled trials comparing TPO mimetics with placebo, no further treatment or another TPO mimetic in patients with MDS of all risk groups, without gender, age or ethnicity restrictions. Additional chemotherapeutic treatment had to be equal in both arms.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the quality of trials, disagreements were resolved by discussion. Risk ratio (RR) was used to analyse mortality during study, transformation to AML, incidence of bleeding events, transfusion requirement, all adverse events, adverse events >= grade 3, serious adverse events and platelet response. Overall survival (OS) and progression-free survival (PFS) have been extracted as hazard ratios, but could not be pooled as results were reported in heterogenous ways. Health-related quality of life and duration of thrombocytopenia would have been analysed as standardised mean differences, but no trial reported these outcomes.

MAIN RESULTS

We did not identify any trial comparing one TPO mimetic versus another. We analysed six eligible trials involving 746 adult patients. All trials were reported as randomised and double-blind trials including male and female patients. Two trials compared TPO mimetics (romiplostim or eltrombopag) with placebo, one trial evaluated eltrombopag in addition to the hypomethylating agent azacitidine, two trials analysed romiplostim additionally to a hypomethylating agent (azacitidine or decitabine) and one trial evaluated romiplostim in addition to the immunomodulatory drug lenalidomide. There are more data on romiplostim (four included, completed, full-text trials) than on eltrombopag (two trials included: one full-text publication, one abstract publication). Due to small sample sizes and imbalances in baseline characteristics in three trials and premature termination of two studies, we judged the potential risk of bias of all included trials as high.Due to heterogenous reporting, we were not able to pool data for OS. Instead of that, we analysed mortality during study. There is little or no evidence for a difference in mortality during study for thrombopoietin mimetics compared to placebo (RR 0.97, 95% confidence interval (CI) 0.73 to 1.27, N = 6 trials, 746 patients, low-quality evidence). It is unclear whether the use of TPO mimetics induces an acceleration of transformation to AML (RR 1.02, 95% CI 0.59 to 1.77, N = 5 trials, 372 patients, very low-quality evidence).Thrombopoietin mimetics probably improve the incidence of all bleeding events (RR 0.92, 95% CI 0.86 to 0.99, N = 5 trials, 390 patients, moderate-quality evidence). This means that in the study population, 713 out of 1000 in the placebo arm will have a bleeding event, compared to 656 of 1000 (95% CI 613 to 699) in the TPO mimetics arm. There is little or no evidence for a difference that TPO mimetics significantly diminish the rate of transfusion requirement (RR 0.83, 95% CI 0.66 to 1.05, N = 4 trials, 358 patients, low-quality evidence). No studies were found that looked at quality of life or duration of thrombocytopenia.There is no evidence that patients given TPO mimetics suffer more all adverse events (RR 1.01, 95% CI 0.96 to 1.07, N = 5 trials, 390 patients, moderate-quality evidence). There is uncertainty whether the number of serious adverse events decrease under therapy with TPO mimetics (RR 0.89, 95% CI 0.54 to 1.46, N = 4 trials, 356 patients, very low-quality evidence).We identified one ongoing study and one study marked as completed (March 2015), but without publication of results for MDS patients (only results reported for AML and MDS patients together). Both studies evaluate MDS patients receiving eltrombopag in comparison to placebo.

AUTHORS' CONCLUSIONS

No trial evaluated one TPO mimetic versus another.Six trials including adult patients analysed one TPO mimetic versus placebo, sometimes combined with standard therapy in both arms. Given the uncertainty of the quality of evidence, meta-analyses show that there is little or no evidence for a difference in mortality during study and premature progress to AML. However, these assumptions have to be further explored. Treatment with TPO mimetics resulted in a lower number of MDS patients suffering from bleeding events.There is no evidence for a difference between study groups regarding transfusion requirement. Enlarged sample sizes and a longer follow-up of future trials should improve the estimate of safety and efficacy of TPO mimetics, moreover health-related quality of life should be evaluated. As two ongoing studies currently investigate eltrombopag (one already completed, but without published results), we are awaiting results for this drug.

Romiplostim monotherapy in thrombocytopenic patients with myelodysplastic syndromes: long-term safety and efficacy

Romiplostim can improve platelet counts in about 50% of patients with low- or intermediate 1-risk (lower risk) myelodysplastic syndromes (MDS) and thrombocytopenia, but its long-term toxicity and efficacy are not known. This open-label extension study evaluated the long-term safety and efficacy of romiplostim in 60 patients with lower risk MDS and platelet counts ≤50 × 109 /l. The primary endpoint was adverse event (AE) incidence. Secondary endpoints were efficacy parameters, including bleeding events and platelet response. Median (range) treatment time in the extension study and the median observation times thereafter were 25 (2-181) and 57 (11-209) weeks, respectively. Treatment-related AEs and serious AEs were reported in 14/60 (23%) and 4/60 (7%) patients, respectively. Progression to acute myeloid leukaemia (AML) occurred in two patients after 44 and 46 weeks. Patients (n = 34, 57%) with a platelet response were further evaluated for length of response. Median (range) response duration was 33 (7-174) weeks; 28/34 (82%) patients had a continuous response. Five of 34 patients (15%) had grade ≥3 bleeding events; three when the platelet count was >50 × 109 /l. There were no new safety concerns and the rate of progression to AML was low; response to romiplostim was maintained for most patients.

Optimizing the use of hypomethylating agents in myelodysplastic syndromes: Selecting the candidate, predicting the response, and enhancing the activity

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell disorders that have a substantial impact on patients' quality of life, in addition to causing significant morbidity and mortality. The hypomethylating agents (HMAs) azacitidine and decitabine are approved for use in the United States and in Europe for the treatment of MDS or acute myeloid leukemia (AML) and, in the case of azacitidine, prolong survival in higher-risk patients. Neither is curative, though, and given the lack of clear treatment guidelines after HMA treatment failure, it is imperative to optimize patient selection and identify the right timing of HMA treatment initiation and response evaluation to maximize patient benefit. Initiatives to improve outcomes have focused on HMA-based drug combinations to enhance HMA activity or treat MDS using complementary drug mechanisms of action. In this review, we will summarize the available data to aid decision-making while treating MDS patients with HMAs.

Management of lower-risk myelodysplastic syndromes without del5q: current approach and future trends

INTRODUCTION

Myelodysplastic syndromes (MDS) are characterized by progressive bone marrow failure manifesting as blood cytopenia and a variable risk of progression into acute myeloid leukemia. MDS is heterogeneous in biology and clinical behavior. MDS are generally divided into lower-risk (LR) and higher-risk (HR) MDS. Goals of care in HR-MDS focus on changing the natural history of the disease, whereas in LR-MDS symptom control and quality of life are the main goals. Areas covered: We review the epidemiology, tools of risk assessment, and the available therapeutic modalities for LR-MDS. We discuss the use of erythropoiesis stimulating agents (ESAs), immunosuppressive therapy (IST), lenalidomide and the hypomethylating agents (HMAs). We also discuss the predictors of response, combination treatment modalities, and management of iron overload. Lastly, we overview the most promising investigational agents for LR-MDS. Expert commentary: It remains unclear how to best incorporate a wealth of new genetic and epigenetic prognostic markers into risk assessment tools especially for LR-MDS patients. Only a subset of patients respond to current treatment modalities and most responders eventually lose their response. Once standard therapeutic options fail, management becomes more challenging. Combination-based approaches have been largely unsuccessful. Among the most promising investigational are the TPO agonists, TGF- β pathway inhibitors, telomerase inhibitors, and the splicing modifiers.

Lenalidomide use in myelodysplastic syndromes: Insights into the biologic mechanisms and clinical applications

Myelosysplastic syndromes (MDS) include a heterogeneous group of clonal myeloid neoplasms characterized by ineffective hematopoiesis leading to blood cytopenias and a variable risk of progression into acute myeloid leukemia (AML). Although the hypomethylating agent azacitidine prolongs survival among patients with higher risk (HR)-MDS compared with conventional care, no drug has been shown conclusively to prolong survival or delay progression to AML among patients with lower-risk MDS (LR-MDS). Lenalidomide is the drug with the most impressive clinical activity in the subset of anemic LR-MDS patients who harbor a deletion of the long arm of chromosome 5 (5q-), where it leads to high rates of transfusion independence and cytogenetic responses. Furthermore, lenalidomide delays progression to AML and prolongs survival among responders. In this article, we review the recently recognized mechanisms of action of lenalidomide and discuss the most recent clinical data regarding its use in patients with both 5q- MDS as well as non-5q- MDS. Finally, we forecast the future directions to improve the efficacy of lenalidomide in MDS with and without 5q-. Cancer 2017;123:1703-1713. © 2017 American Cancer Society.

Treatment of low-risk myelodysplastic syndromes

The majority of myelodysplastic syndrome (MDS) patients belong to the International Prognostic Scoring System (IPSS) and IPSS-revised (IPSS-R) lower-risk categories. Their precise diagnostics and prognostic stratification is often a challenge, but may ensure the optimization of therapy. The availability of diverse treatment options has significantly improved the quality of life and survival of this group of patients. Anemia is the most relevant cytopenia in terms of frequency and symptoms in lower-risk MDS, and may be treated successfully with erythropoietic stimulating agents, provided a careful selection is performed on the basis of IPSS-R, endogenous erythropoietin levels, and transfusion independence. Doses and duration of therapy of erythropoietic-stimulating agents (ESAs) are critical to determine efficacy. In case a patient fails ESA treatment, the available options may include lenalidomide (approved for del5q positive cases), hypomethylating agents, and a rather large number of experimental agents, whose clinical trials should be offered to a larger number of MDS patients. The choice for second-line treatment must take into account biologic, cytogenetic, and molecular-identified characteristics of individual patients, as well as frailty and comorbidities. Other cytopenias are less frequently presenting as isolated. Specific therapy for thrombocytopenia has been proposed in experimental clinical trials with thrombomimetic agents that have shown good efficacy, but raised some safety concern. Although neutropenia is targeted symptomatically with growth factor supportive care, the immunosuppressive treatments are indicated mainly for pancytopenic, hypoplastic lower-risk MDS; they are not widely used because of their toxicity, despite the fact that they may induce responses. Finally, hematopoietic stem cell transplant is the curative option also for lower-risk MDS and timing should be carefully evaluated, balancing toxicity and the possibility of survival advantage. Finally, even when considered suitable for lower-risk MDS, transplant application is limited to the rarer fit and younger MDS patient.