Thrombopoietin receptor agonists for preparing adult patients with immune thrombocytopenia to splenectomy: results of a retrospective, observational GIMEMA study

Red blood cell distribution width is a useful biomarker to predict bleeding and thrombosis risks in patients with immune thrombocytopenic purpura

Bleeding and thrombosis are common complications during immune thrombocytopenic purpura (ITP) treatment. There is a strong need to predict bleeding and thrombosis risks before ITP treatment to optimize therapy and appropriately manage these complications. We performed a retrospective cohort study of 120 patients with primary ITP to identify a biomarker to predict bleeding and thrombosis. We compared blood test results at diagnosis between patients with and without bleeding or thrombosis episodes. The standard deviation of red blood cell distribution width (RDW-SD) differed significantly between those with and without bleeding and between those with and without thrombosis, leading us to identify it as a variable representative of risk. RDW-SD was significantly associated with patient age and with histories of several vascular diseases. Multivariate regression analyses showed that RDW integrated several variables associated with vascular risks. RDW-SD was significantly associated with difficulty with corticosteroid discontinuation (hazard ratio [HR], 2.22, p = 0.01), incidence of bleeding (HR, 2.75, p< 0.01), incidence of thrombosis (HR, 2.67, p< 0.01) and incidence of infection (HR, 1.78, p = 0.04). The RDW-SD value at the time of ITP diagnosis is a useful biomarker to predict the risks of bleeding, thrombosis, and other complications.

Primary and secondary immune thrombocytopenia (ITP): Time for a rethink

There are not many publications that provide a holistic view of the management of primary and secondary ITP as a whole, reflecting the similarities and differences between the two. Given the lack of major clinical trials, we believe that comprehensive reviews are much needed to guide the diagnosis and treatment of ITP today. Therefore, our review addresses the contemporary diagnosis and treatment of ITP in adult patients. With respect to primary ITP we especially focus on establishing the management of ITP based on the different and successive lines of treatment. Life-threatening situations, "bridge therapy" to surgery or invasive procedures and refractory ITP are also comprehensively reviewed here. Secondary ITP is studied according to its pathogenesis by establishing three major differential groups: Immune Thrombocytopenia due to Central Defects, Immune Thrombocytopenia due to Blocked Differentiation and Immune Thrombocytopenia due to Defective Peripheral Immune Response. Here we provide an up-to-date snapshot of the current diagnosis and treatment of ITP, including a special interest in addressing rare causes of this disease in our daily clinical practice. The target population of this review is adult patients only and the target audience is medical professionals.

Nationwide Survey on the Use of Thrombopoietin Receptor Agonists (TPO-RA) for the Management of Immune Thrombocytopenia in Current Clinical Practice in Italy

Background

Two thrombopoietin receptor agonists (TPO-RA), romiplostim and eltrombopag, are currently widely adopted as second-line ITP therapy even in the absence of robust evidence on their comparative advantages over rituximab or splenectomy or their preferential use in some specific clinical contexts.

Methods

An online survey was distributed between May 2021 and June 2021 to collect standardized information on TPO-RA use in Italy.

Results

Eighty-eight hematologists from 79 centers completed the survey. Eighty-four percent would use TPO-RA earlier than formally indicated, without a preference for young or elderly in 82% of respondents. No clear preference for either romiplostim or eltrombopag was indicated. Seventy-two percent would use TPO-RA in young patients aiming at a complete response followed by tapering, a strategy considered by only 16% in the elderly. Switching between the two agents was considered appropriate in case of insufficient response or intolerance. Tapering schedule by reducing the dosage and prolonging the intervals between administrations was preferred by 73% of respondents. TPO-RA was considered a risk factor for thrombosis by only 35%, and 94% would administer TPO-RA in elderly patients also in the presence of other thrombotic risk factors. Thirty-three percent of respondents would withdraw TPO-RA in case of thrombosis. The TPORA administration has been reported to be preferred over anti-CD20 or splenectomy by about half of the participants due to the ongoing COVID-19 pandemic.

Conclusions

Significant discrepancies in TPO-RA use emerged from the survey, and participants would appreciate consensus-based specific guidance on the practical use of TPO-RA.

Effect of Thrombopoietin Receptor Agonist on Pregnant Mice

Thrombopoietin receptor agonists (TPO-RAs) are an effective treatment for refractory immune thrombocytopenia (ITP). However, the use of TPO-RAs is limited for ITP in pregnant women due to concerns about fetal toxicity. In this study, we examined the effects of romiplostim, one of the TPO-RAs, on pregnant mice. The mice were injected subcutaneously with romiplostim (1, 5, 10, 30, and 100 μg/kg) on gestational days (GD) 1, 8, and 15. We evaluated maternal and fetal platelet and megakaryocyte counts (MK), fetal weight at birth, placental morphology, and miscarriage rates. Romiplostim increased platelet and MK counts in pregnant mice at all doses and in fetuses at doses above 10 µg/kg. Fetal weight at birth was slightly reduced at a dose of 100 μg/kg, but there were no significant differences in placental weight, spiral artery wall thickness, placental growth factor signal changes, or the rate of resorption at that dosage. The dose of romiplostim used clinically for ITP patients (1–10 μg/kg) did not show any adverse effects on pregnant mice. Although the results of the present study are encouraging, until there are more conclusive data, the use of romiplostim should be evaluated individually in severe, life-threatening cases, and all relevant ethical aspects should be considered.

Dentoalveolar Procedures in Immune Thrombocytopenia; Systematic Review and an Institutional Guideline

Background  Dentoalveolar procedures in immune thrombocytopenia (ITP) pose a risk of bleeding due to thrombocytopenia and infection due to immunosuppressive treatments. We aimed to systematically review the safety and management of dentoalveolar procedures in ITP patients to create practical recommendations.

Methods  PubMed, Embase, Cochrane, and Cinahl were searched for original studies on dentoalveolar procedures in primary ITP patients. We recorded bleeding- and infection-related outcomes and therapeutic strategies. Clinically relevant bleeding was defined as needing medical attention.

Results  Seventeen articles were included, of which 12 case reports/series. Overall, the quality of the available evidence was poor. Outcomes and administered therapies (including hemostatic therapies and prophylactic antibiotics) were not systematically reported. At least 73 dentoalveolar procedures in 49 ITP patients were described. The range of the preoperative platelet count was 2 to 412 × 10 ⁹ /L. Two clinically relevant bleedings (2%) were reported in the same patient of which one was life-threatening. Strategies used to minimize the risk of bleeding were heterogeneous and included therapies to increase platelet count, antifibrinolytics, local measures, and minimally invasive techniques. Reports on the occurrence of bleedings due to anesthetics or infection were lacking.

Conclusion  Based on alarmingly limited data, clinically relevant bleedings and infections after dentoalveolar procedures in ITP patients seem rare. Awaiting prospective and controlled studies to further evaluate these risks and the efficacy of therapeutic interventions, we provided our institutional guideline to guide the management of dentoalveolar procedures in ITP patients.

Relationship between Hepatitis B virus infection and platelet production and dysfunction

Hepatitis B virus (HBV) is a kind of hepatotropic DNA virus. The main target organ is liver, except for liver, HBV has been found in a variety of extrahepatic tissues, such as kidney, thyroid, pancreas, bone marrow, etc. HBV can cause severe complications by invading these tissues. Among them, pancytopenia is one of the common complications, especially thrombocytopenia that causes life-threatening bleeding. However, the mechanism of thrombocytopenia is unclear and the treatment is extremely difficult. It has been confirmed that HBV has a close relationship with platelets. HBV can directly infect bone marrow, inhibit platelet production, and accelerate platelet destruction by activating monocyte-macrophage system and immune system. While platelets act as a double-edged sword to HBV. On one hand, the activated platelets can degranulate and release inflammatory mediators to help clear the viruses. Furthermore, platelets can provide anti-fibrotic molecules to improve liver functions and reduce hepatic fibrosis. On the other hand, platelets can also cause negative effects. The infected platelets collect HBV-specific CD8⁺ T cells and nonspecific inflammatory cells into liver parenchyma, inducing chronic inflammation, liver fibrosis and hepatic carcinoma. This article explores the interaction between HBV infection and platelets, providing a theoretical basis for clinical treatment of thrombocytopenia and severe hemorrhage caused by HBV infection.

Immune thrombocytopenia

INTRODUCTION

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by a low platelet count (<100 × 10⁹/L) with an increased risk of bleeding. Recent (2019) guidelines from the International Consensus Report (ICR) expert panel and the American Society of Hematology (ASH) provide updated recommendations for the diagnosis and management of ITP.

AREAS COVERED

The 2019 ICR and ASH guidelines are reviewed, and differences and similarities highlighted. Clinical approaches to the treatment of ITP are discussed, including the role of fostamatinib which is an approved treatment option in adult patients who are refractory to other treatments.

EXPERT OPINION

The 2019 ICR and ASH guidelines reflect recent changes in the management of ITP. Current treatment approaches for ITP are more rational and evidence-based than in the past. Patients should be treated based on their needs rather than on disease stage, and patient-specific outcomes, (e.g. quality of life) should be considered. Whilst corticosteroids are the mainstay of initial ITP treatment their use should be limited. For subsequent treatment, the use of thrombopoietin receptor agonist (TPO-RA) agents, fostamatinib and rituximab in adults is supported by robust evidence. Rituximab and recently approved fostamatinib offer viable alternatives to splenectomy.

Severe Portal Vein Thrombosis During Eltrombopag Treatment Concomitant Splenectomy for Immune Thrombocytopenia

The treatment of immune thrombocytopenia (ITP) has recently changed; however, each treatment has not only advantages, but also disadvantages, and may have unexpected complications. We describe an instructive case of ITP that was complicated by severe portal vein thrombosis during treatment with eltrombopag, an oral thrombopoietin-receptor agonist (TPO-RA) drug, plus prednisolone (PSL) concomitant splenectomy. A male ITP patient who had been receiving eltrombopag treatment for more than four years at our department underwent a splenectomy at the age of 51. Soon after splenectomy, splenic vein and portal vein thrombosis developed, while splenectomy was ineffective. The patient resumed eltrombopag treatment after thrombosis disappeared. Although fluctuations in PLT were observed, eltrombopag and PSL were used together for a while. Subsequently, lower-limb deep vein thrombosis recurred, and edoxaban tosylate was administered for a total of 8.4 months. More than three years after splenectomy, at the age of 54, abdominal computed tomography (CT) revealed a continuous thrombus extending from the intrahepatic portal vein to the superior mesenteric vein. In patients with ITP in whom splenectomy fails and treatment with a TPO-RA ± PSL needs to be continued, clinicians should be aware of the possibility of abdominal thrombotic adverse events, such as severe portal vein thrombosis, by following-up on CT imaging, not only in the short term but also in the medium-long term.

Lessons Learned Using Real-World Data to Emulate Randomized Trials: A Case Study of Treatment Effectiveness for Newly Diagnosed Immune Thrombocytopenia

Regulatory agencies are increasingly considering real-world evidence (RWE) to support label expansions of approved medicines. We conducted a comparative effectiveness study to emulate a proposed randomized trial of romiplostim vs. standard-of-care (SOC) therapy among patients with recently diagnosed (≤12 months) immune thrombocytopenia (ITP), that could support expansion of the romiplostim label. We discuss challenges that we encountered and solutions that were developed to address those challenges. Study size was a primary concern, particularly for romiplostim initiators, given the rarity of ITP and the stringent trial eligibility criteria. For this reason, we leveraged multiple data sources (Nordic Country Patient Registry for Romiplostim; chart review study of romiplostim initiators in Europe; Flatiron Health EMR linked with MarketScan claims). Additionally, unlike the strictly controlled clinical trial setting, platelet counts were not measured at regular intervals in the observational data sources, and therefore the end point of durable platelet response often used in trials could not be reliably measured. Instead, the median platelet count was chosen as the primary end point. Ultimately, while we observed a slightly higher median platelet count in the romiplostim group vs. SOC, precision was limited because of small study size (median difference was 11 × 10⁹ /L (95% CI: -59, 81)). We underscore the importance of conducting comprehensive feasibility assessments to identify fit-for-purpose data sources with sufficient sample size, data elements, and follow-up. Beyond technical challenges, we also discuss approaches to increase the credibility of RWE, including systematic incorporation of clinical expertise into study design decisions, and separation between decision makers and the data.

Update on diagnosis and treatment of immune thrombocytopenia

BACKGROUND

Immune thrombocytopenia (ITP) is a heterogeneous acquired disorder characterized by isolated thrombocytopenia whose exact pathogenesis is not yet clear. Depending upon the presence or absence of an underlying treatable cause, ITP can be categorized as primary or secondary. Primary ITP is a diagnosis of exclusion and there is no gold standard test for its confirmation. Recent drug intake, infections, lymphoproliferative disorders, and connective tissue disorders should be ruled out before labeling a patient as primary ITP.

AREA COVERED

This review summarizes a comprehensive update on the diagnostic and therapeutic modalities for ITP. We reviewed the literature using GOOGLE SCHOLAR, PUBMED and ClinicalTrial.gov databases as needed to support the evidence. We searched the literature using the following keywords: 'immune thrombocytopenia,' 'idiopathic thrombocytopenic purpura,' 'thrombocytopenia,' 'immune thrombocytopenic purpura,' and 'isolated thrombocytopenia'.

EXPERT OPINION

We believe that more detailed studies are required to understand the exact pathophysiology behind ITP. The first-line drugs like corticosteroids have both short-term and long-term adverse effects. This brings the need to explore effective alternative medications and to reconsider their role in ITP treatment algorithm if guidelines can be modified based on new studies.

Romiplostim in adults with newly diagnosed or persistent immune thrombocytopenia

Introduction: Three distinct phases are recognized in immune thrombocytopenia (ITP): newly diagnosed (≤3 months after diagnosis), persistent (>3-12 months after diagnosis), and chronic (>12 months). Several international guidelines/expert recommendations have been released in the past 2 years regarding the treatment of newly diagnosed/persistent ITP. Areas covered: Across the guidelines/expert recommendations, thrombopoietin receptor agonists (TPO-RAs), including romiplostim (the focus of this review), are recommended in newly diagnosed or persistent ITP for patients who fail to respond to corticosteroids or intravenous immunoglobulin (or where these are contraindicated). To identify data relating to romiplostim in adults with newly diagnosed or persistent ITP, we conducted a search of PubMed (with no time limit applied) and abstracts from 2019 EHA/ASH meetings using the term 'romiplostim.' Expert opinion: The findings from nine clinical trials, six real-world studies and ten case reports provide insight into the early use of romiplostim, which could help to reduce exposure to the adverse effects associated with prolonged corticosteroid use, as well as reduce the risk of severe bleeding. Additionally, given the durable responses observed in patients with newly diagnosed/persistent ITP, as well as the potential for treatment-free responses following discontinuation, romiplostim might help to avoid the need for subsequent treatment.

Why thromboembolism occurs in some patients with thrombocytopenia and treatment strategies

Platelets play such an important role in the process of thrombosis that patients with thrombocytopenia generally have an increased risk of bleeding. However, abnormal thrombotic events can sometimes occur in patients with thrombocytopenia, which is unusual and inexplicable. The treatments for thrombocytopenia and thromboembolism are usually contradictory. This review introduces the mechanisms of thromboembolism in patients with different types of thrombocytopenia and outlines treatment recommendations for the prevention and treatment of thrombosis. According to the cause of thrombocytopenia, this article addresses four etiologies, including inherited thrombocytopenia (Myh9-related disease, ANKRD26-associated thrombocytopenia, Glanzmann thrombasthenia, Bernard-Soulier syndrome), thrombotic microangiopathy (thrombotic thrombocytopenic purpura, atypical hemolytic uremic syndrome, hemolytic uremic syndrome, Hemolysis Elevated Liver enzymes and Low Platelets syndrome, disseminated intravascular coagulation), autoimmune-related thrombocytopenia (immune thrombocytopenic purpura, antiphospholipid syndrome, systemic lupus erythematosus), and acquired thrombocytopenia (Infection-induced thrombocytopenia and drug-induced thrombocytopenia, heparin-induced thrombocytopenia). We hope to provide more evidence for clinical applications and future research.

Perioperative oral eltrombopag versus intravenous immunoglobulin in patients with immune thrombocytopenia: a non-inferiority, multicentre, randomised trial

BACKGROUND

Patients with immune thrombocytopenia are at risk of bleeding during surgery, and intravenous immunoglobulin is commonly used to increase the platelet count. We aimed to establish whether perioperative eltrombopag was non-inferior to intravenous immunoglobulin.

METHODS

We did a randomised, open-label trial in eight academic hospitals in Canada. Patients were aged at least 18 years, with primary or secondary immune thrombocytopenia and platelet counts less than 100 × 10⁹ cells per L before major surgery or less than 50 × 10⁹ cells per L before minor surgery. Previous intravenous immunoglobulin within 2 weeks or thrombopoietin receptor agonists within 4 weeks before randomisation were not permitted. Patients were randomly assigned to receive oral daily eltrombopag 50 mg from 21 days preoperatively to postoperative day 7 or intravenous immunoglobulin 1 g/kg or 2 g/kg 7 days before surgery. Eltrombopag dose adjustments were allowed weekly based on platelet counts. The randomisation sequence was generated by a computerised random number generator, concealed and stratified by centre and surgery type (major or minor). The central study statistician was masked to treatment allocation. The primary outcome was achievement of perioperative platelet count targets (90 × 10⁹ cells per L before major surgery or 45 × 10⁹ cells per L before minor surgery) without rescue treatment. We did intention-to-treat and per-protocol analyses using an absolute non-inferiority margin of -10%. This trial is registered with ClinicalTrials.gov, NCT01621204.

FINDINGS

Between June 5, 2013, and March 7, 2019, 92 patients with immune thrombocytopenia were screened, of whom 74 (80%) were randomly assigned: 38 to eltrombopag and 36 to intravenous immunoglobulin. Median follow-up was 50 days (IQR 49-55). By intention-to-treat analysis, perioperative platelet targets were achieved for 30 (79%) of 38 patients assigned to eltrombopag and 22 (61%) of 36 patients assigned to intravenous immunoglobulin (absolute risk difference 17·8%, one-sided lower limit of the 95% CI 0·4%; p_{non-inferiority}=0·005). In the per-protocol analysis, perioperative platelet targets were achieved for 29 (78%) of 37 patients in the eltrombopag group and 20 (63%) of 32 in the intravenous immunoglobulin group (absolute risk difference 15·9%, one-sided lower limit of the 95% CI -2·1%; p_{non-inferiority}=0·009). Two serious adverse events occurred in the eltrombopag group: one treatment-related pulmonary embolism and one vertigo. Five serious adverse events occurred in the intravenous immunoglobulin group (atrial fibrillation, pancreatitis, vulvar pain, chest tube malfunction and conversion to open splenectomy); all were related to complications of surgery. No treatment-related deaths occurred.

INTERPRETATION

Eltrombopag is an effective alternative to intravenous immunoglobulin for perioperative treatment of immune thrombocytopenia. However, treatment with eltrombopag might increase risk of thrombosis. The decision to choose one treatment over the other will depend on patient preference, resource limitations, cost, and individual risk profiles.

FUNDING

GlaxoSmithKline and Novartis.

[Adult immune thrombocytopenia and thrombopoietin receptor agonist: Ten years later]

Ten years after their licence in France, the use of the two thrombopoietin receptor agonists (TPO-RA), eltrombopag and romiplostim, has deeply modified the landscape of immune thrombocytopenia (ITP) treatment. In this review, we summarise data on efficacy and safety of these treatments during ITP, as well as their use in clinical practice. Their place in therapeutic strategy, the recent description of persistant remission after discontinuation of TPO-RA, and future new thrombopoietic agents are also discussed. Their use has progressively increased and early use at a newly diagnosed stage of the disease is under evaluation. However physician have to keep in mind that thromboembolism rates appear to be higher with TPO-RA treatment in ITP patients at high risk of thrombosis, and that data from "real-life" studies with very long term follow up are not available. Finally, the cost of these treatments should also be evaluated in future therapeutic strategies comparisons.

Report of a 'consensus' on the lines of therapy for primary immune thrombocytopenia in adults, promoted by the Italian Gruppo di Studio delle Piastrine

Despite the publication in 2009 of a paper on 'terms and definitions of immune thrombocytopenia' (ITP), some unresolved issues remain and are reflected by the disagreement in the treatment suggested for primary ITP in adults. Considering that these disagreements could be ascribed to non-shared goals, we generated a 'consensus' on some terms, definitions, and assertions useful for classifying the different lines of treatment for primary ITP in adults according to their indications and goals. Agreement on the appropriateness of the single assertions was obtained by consensus for the following indicators: 1. classification of four 'lines of therapy'; 2. acceptance of the expression 'sequences of disease' for the indications of the respective four lines of treatment; 3_I . practicability of splenectomy; 3_Ib . acceptance, with only some exceptions, of a 'timing for elective splenectomy of 12 months'; and 4_a-d . 'goals of the four lines of therapy.' On the basis of the consensus, a classification of four lines of treatment for primary ITP in adults was produced. In our opinion, this classification, whose validity is not influenced by the recently published new guidelines of the American Society of Hematology (ASH) and reviews, could reduce the disagreement that still exists regarding the treatment of the disease.

Impact of Platelet Counts, Surgical Methods, and Preoperative Platelet Transfusion on the Outcome of Splenectomy for Immune Thrombocytopenia

INTRODUCTION

Splenectomy is an important and potentially curative treatment for immune thrombocytopenia (ITP). Laparoscopic splenectomy (LS) has replaced open splenectomy (OS) as the standard approach. The prognostic role of platelet count and the clinical indication of preoperative platelet transfusion are not entirely clear.

METHODS

We designed a study to explore the prognostic impact of surgical methods, platelet count, and platelet transfusion in a large, single-institute, long-term cohort of ITP patients.

RESULT

In 118 ITP patients, there was no difference between OS and LS in response and surgical complications. The overall response rate was 77% and the complete response (CR) rate was 70%. Patients with a CR had a trend towards a higher baseline platelet count. A stable platelet count 14-28 days after splenectomy was associated with a sustained long-term response. Patients requiring preoperative platelet transfusion had a lower preoperative platelet count and were more likely to need postoperative transfusion of red blood cells and platelets. They also had a lower postoperative platelet count than the nontransfusion group. Relapse-free survival did not differ.

CONCLUSIONS

Baseline and postoperative platelet counts are apparently associated with the treatment response to splenectomy but the difference did not reach statistical significance. Preoperative platelet transfusion did not overcome the disadvantage of thrombocytopenia and was not recommended when other preparative measures are available.

Updated international consensus report on the investigation and management of primary immune thrombocytopenia

Over the last decade, there have been numerous developments and changes in treatment practices for the management of patients with immune thrombocytopenia (ITP). This article is an update of the International Consensus Report published in 2010. A critical review was performed to identify all relevant articles published between 2009 and 2018. An expert panel screened, reviewed, and graded the studies and formulated the updated consensus recommendations based on the new data. The final document provides consensus recommendations on the diagnosis and management of ITP in adults, during pregnancy, and in children, as well as quality-of-life considerations.

Medical management of acute radiation syndrome and associated infections in a high-casualty incident

A high-casualty incident may result in a significant human toll due to the inability of a community to meet the health care demands of the population. A successful medical response requires health care facilities to not only communicate and integrate medical services, meet surge capacity, protect health care workers and implement triage and treatment protocols, but also to provide the venue for clinical management of acute radiation injuries and their associated infections. Today, clinical management is primarily guided by the recommendations of a Consultancy that were made at the World Health Organization (WHO). This international consensus was reached on evidence-based, clinical management of each of the four sub-syndromes that compose acute radiation syndrome (ARS), including the hematopoietic subsyndrome (HS), gastrointestinal subsyndrome (GIS), neurovascular subsyndrome (NVS) and cutaneous subsyndrome (CS). Major findings in studies meeting inclusion criteria for management strategies for HS were that (i) no randomized controlled studies of medical countermeasures have been (or will likely ever be) performed for ARS cases, (ii) the data for management of HS are restricted by the lack of comparator groups, and (iii) reports of countermeasures for management of injury to non-hematopoietic organs are often incompletely described. Here, (i) recommendations made in Geneva are summarized; (ii) the analysis of countermeasures for HS is updated by review of two additional cases and extended to published reports not meeting inclusion criteria; and (iii) guidelines are provided for management of microbial infections based upon patient risk for prolonged immunosuppression.

Thrombopoetin receptor agonist therapy in thrombocytopenia: ITP and beyond

Eltrombopag is well established in treatment of severe immune thrombocytopenia (ITP) and is increasingly commonplace in second-line management. A role is also suggested for both bridging therapy for surgery, as well as treating thrombocytopenia due to non-immune aetiologies. We present the largest single-centre experience with eltrombopag, with our cohort of 62 patients. Patients with severe ITP (n = 34) had 91·2% response, which was sustained over a median of 18·5 months. In 41·4% of ITP cases (n = 14), complete response (CR- platelet count >100 × 10⁹ /l) was achieved and in 2 cases, therapy was stopped and CR maintained. In our bridging group (n = 15) with a higher baseline platelet count, 93·3% achieved a CR. In the non-ITP group (n = 13), a response was achieved in 76·9%. In all groups, side effects were transient, with the drug discontinued in 2 patients due to minor complications (rash, nausea, diarrhoea). We conclude that eltrombopag is both effective and well tolerated as therapy in severe ITP. It is also advantageous in ITP patients who do not normally require therapy, but need a temporary platelet count boost pre-procedure. Furthermore, there are potentially far wider implications for the use of eltrombopag in counteracting thrombocytopenia beyond ITP, which merit further investigation.

From chronic immune thrombocytopenia to severe aplastic anemia: recent insights into the evolution of eltrombopag

Thrombopoietin (TPO) is the most potent cytokine stimulating thrombopoiesis. Therapy with exogenous TPO is limited by the formation of antibodies cross-reacting with endogenous TPO. Mimetics of TPO are compounds with no antigenic similarity to TPO. Eltrombopag is an orally-active nonpeptide small molecule that binds to the transmembrane portion of the TPO receptor MPL. Initial trials of eltrombopag have centered on immune thrombocytopenia (ITP), which is due to both increased destruction and decreased production of platelets. Eltrombopag at 25-75 mg/day has been shown to be highly effective in raising the platelet count in ITP with suboptimal response to immunosuppression and splenectomy. These successful results led to the exploration of eltrombopag in other thrombocytopenic disorders. In hepatitis C viral infection, eltrombopag raises the platelet count sufficiently enough to allow treatment with ribavirin and pegylated interferon. Because MPL is expressed on hematopoietic cells, eltrombopag use in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) might enhance leukemic proliferation. Clinical trials of eltrombopag in MDS and AML, however, have shown amelioration of thrombocytopenia without promoting disease progression. In severe aplastic anemia (SAA) not responding to immunosuppression with anti-thymocyte globulin (ATG) and cyclosporine, eltrombopag as a single agent at 150-300 mg/day results in an overall response rate of 40-70%. At high doses, adverse effects including pigmentation, gastrointestinal upset and hepatic derangement have become evident. Current studies have examined the first-line use of eltrombopag in combination with ATG in SAA. In a recent study, eltrombopag used at 150 mg/day with horse ATG resulted in an overall response rate of 90% in newly diagnosed SAA patients, with a complete response rate of about 50%. Clonal karyotypic aberrations are, however, found in 10-20% of SAA patients treated with eltrombopag. The safety and efficacy of eltrombopag in SAA require further evaluation, particularly when it is used with less intensive immunosuppression.

Balancing Therapy with Thrombopoietin Receptor Agonists and Splenectomy in Refractory Immune Thrombocytopenic Purpura: A Case of Postsplenectomy Thrombocytosis Requiring Plateletpheresis

Immune thrombocytopenic purpura (ITP) causes thrombocytopenia through the autoimmune destruction of platelets. Corticosteroids remain the first line of therapy, and traditionally splenectomy has been the second. While the availability of thrombopoietin receptor agonists (TPO-RAs) has expanded treatment options, there is little data for the ideal management of these agents in preparation for splenectomy. Thrombocytosis has been reported after splenectomy in patients treated with TPO-RA preoperatively, with one prior case requiring plateletpheresis for symptomatic thrombocytosis. We present a case report and review of the literature pertaining to this complication and provide recommendations for preventing postsplenectomy thrombocytosis in ITP patients on TPO-RAs.