Safety and efficacy of romiplostim in splenectomized and nonsplenectomized patients with primary immune thrombocytopenia

Treatment of Immune Thrombocytopenia: Contextualization from a Historical Perspective

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by an isolated decrease in platelet count and an increased risk of bleeding. The pathogenesis is complex, affecting multiple components of the immune system and causing both peripheral destruction of platelets and inadequate production in the bone marrow. In this article, we review the treatment of ITP from a historical perspective, discussing first line and second line treatments, and management of refractory disease.

Real-world use of thrombopoietin receptor agonists for the management of immune thrombocytopenia in adult patients in the United Kingdom: Results from the TRAIT study

Few studies have reported the real-world use of both romiplostim and eltrombopag in immune thrombocytopenia (ITP). TRAIT was a retrospective observational study aimed to evaluate the platelet responses and adverse effects associated with the use of these thrombopoietin receptor agonists (TPO-RAs) in adult patients with ITP in the United Kingdom. Of 267 patients (median age at diagnosis, 48 years) with ITP (primary ITP [n = 218], secondary ITP [n = 49]) included in the study, 112 (42%) received eltrombopag and 155 (58%) received romiplostim as the first prescribed TPO-RA. A platelet count ≥30 × 109/L was achieved in 89% of patients with the first TPO-RA treatments, while 68% achieved a platelet count ≥100 × 109/L. Treatment-free response (TFR; platelet count ≥30 × 109/L, 3 months after discontinuing treatment) was achieved by 18% of the total patients. Overall, 61 patients (23%) switched TPO-RAs, most of whom achieved platelet counts ≥30 × 109/L with the second TPO-RA (23/25 who switched from eltrombopag to romiplostim [92%]; 28/36 who switched from romiplostim to eltrombopag [78%]). TFR was associated with secondary ITP, early TPO-RA initiation after diagnosis, the presence of comorbidity and no prior splenectomy or treatment with steroids or mycophenolate mofetil. Both TPO-RAs had similar efficacy and safety profiles to those reported in clinical studies.

Thrombopoietin-receptor agonists for adult patients with immune thrombocytopenia: a narrative review and an approach for managing patients fasting intermittently

Introduction

Thrombopoietin-receptor agonist (TPO-RAs) currently represent the state of art for treating immune thrombocytopenia. Their different molecular structures contribute to the difference in their pharmacodynamics and pharmacokinetics. This narrative review aims to provide an overview of the current TPO-RAs approved for primary immune thrombocytopenia (romiplostim, eltrombopag, avatrombopag) and the effect of intermittent fasting in adult patients receiving TPO-RAs.

Areas covered

Literature was searched with no limits on date or language, using various combinations of keywords. Data on the pharmacokinetics, pharmacodynamics, efficacy, and safety of TPO-RAs and the effect of intermittent fasting were summarized.

Expert opinion

Switching between TPO-RAs is a useful strategy to tackle some associated limitations. Romiplostim and avatrombopag have an advantage over eltrombopag as they do not require any dietary restrictions. In cases where romiplostim and avatrombopag are unavailable, patients should be educated on the appropriate administration, possible interactions, and dietary restrictions before initiating eltrombopag.

Treatment of Acute Ischaemic Stroke and Concomitant Multiple Arterial Splanchnic Thromboses in a Patient with Immune Thrombocytopenia on Thrombopoietin Agonist: A Case Report

Immune thrombocytopenia (ITP) is an autoimmune blood disorder characterised by isolated severe thrombocytopenia. Arterial thrombotic events, such as acute ischaemic stroke (AIS), are rare complications. A 56-year-old woman with chronic ITP on eltrombopag and dexamethasone therapy presented to the emergency department due to AIS in the vertebrobasilar territory, and lower abdominal pain. The computed tomography (CT) scan of the head was unremarkable, whereas CT angiography revealed left vertebral artery occlusion. As the platelet count was sufficient, intravenous thrombolysis (IVT) was initiated. However, after 15 min, an anaphylactic reaction occurred, which was appropriately solved. Although the IVT was prematurely stopped, the NIHSS score improved from 7 to 2, and the follow-up head CT scan remained unremarkable. CT angiography of the thoracoabdominal aorta revealed multiple thrombi in the infrarenal aorta, inferior mesenteric artery (IMA), and left renal artery. The abdominal pain subsided after IVT, but recurred within 24 h. Repeated CT angiography showed ischaemia of the descending colon, with persistent IMA occlusion. After the hemicolectomy condition stabilised. Discrete left-sided ataxia and impaired sensation were the only neurological sequelae. We found two articles reporting only three patients with ITP who suffered AIS and were treated with IVT. A favourable outcome was observed in two cases, while one patient suffered an intracranial haemorrhage (ICH) and died. A review of AIS cases with undefined thrombocytopenia treated with IVT reported ICH in up to 6.8% of patients. Our case suggests that IVT for AIS may be effective in patients with ITP. Further data are needed to better clarify this issue.

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.

Current Concepts in the Diagnosis and Management of Adult Primary Immune Thrombocytopenia: Our Personal View

Primary immune thrombocytopenia (ITP) is an acquired blood disorder that causes a reduction in circulating platelets with the potential for bleeding. The incidence of ITP is slightly higher in adults and affects more women than men until 60 years, when males are more affected. Despite advances in basic science, primary ITP remains a diagnosis of exclusion. The disease is heterogeneous in its clinical behavior and response to treatment. This reflects the complex underlying pathophysiology, which remains ill-understood. Platelet destruction plays a role in thrombocytopenia, but underproduction is also a major contributing factor. Active ITP is a proinflammatory autoimmune disease involving abnormalities within the T and B regulatory cell compartments, along with several other immunological abnormalities. Over the last several years, there has been a shift from using immunosuppressive therapies for ITP towards approved treatments, such as thrombopoietin receptor agonists. The recent COVID-19 pandemic has hastened this management shift, with thrombopoietin receptor agonists becoming the predominant second-line treatment. A greater understanding of the underlying mechanisms has led to the development of several targeted therapies, some of which have been approved, with others still undergoing clinical development. Here we outline our view of the disease, including our opinion about the major diagnostic and therapeutic challenges. We also discuss our management of adult ITP and our placement of the various available therapies.

Long-term efficacy and safety profile of splenectomy for pediatric chronic immune thrombocytopenia

There are few reports of the long-term efficacy of splenectomy in children with immune thrombocytopenia (ITP). In a 33-year period, we performed splenectomies in 23 pediatric patients with ITP at a single institution in Japan. The age at surgery was 5-22 years with a median of 10 years. The follow-up period was 1-141 months with a median of 48 months. Before surgery, we confirmed the presence or absence of the accessory spleen by contrast-enhanced CT scan and we recommended vaccination with pneumococcal vaccine. Four patients underwent laparotomy before 1998, and 19 patients underwent laparoscopic surgery after 1999. Splenectomy showed high efficacy with a partial response rate of 83% and a complete response rate of 74%. Complete response was maintained in 70% of patients until the end of the observation period, and 91% were able to discontinue long-term management drugs such as steroids. No serious complications such as infectious diseases were observed. Although the number of cases here was small, the long-term efficacy and safety of splenectomy makes it a viable option in pediatric ITP despite the existence of newer therapeutic agents. Further research is necessary to compare the long-term efficacy and safety of splenectomy with new therapeutic agents.

Efficacy and quality of life of Romiplostim in adults and children with immune thrombocytopenia: A review

BACKGROUND

To systematically evaluate the clinical efficacy, drug safety and health-related quality of life (HRQoL) of Romiplostim in adult and child immune thrombocytopenia (ITP) patients.

METHODS

PubMed, EMBASE and Cohrane library databases were searched for all randomized controlled trials published until 2022, and the Review Manager 5.3 was used for meta-analysis.

RESULTS

A total of 9 randomized controlled trials were included in this study. The results of meta-analysis showed that the total platelet response rate and long-term platelet response rate in treatment group were significantly higher than those in control group (P<0.05). There was no statistical significance in the side effects, serious side effects, bleeding events and serious bleeding events between 2 groups (P>0.05). Compared with control group, the HRQoL in ITP adults and children, and parents of ITP children had no statistical significance (P>0.05).

CONCLUSION

Romiplostim has a certain clinical efficacy in ITP adults and children, and relatively small adverse drug reactions. The improvement of Romiplostim on HRQoL in ITP adults and children is not clear.

Gaucher disease carrier with gestational thrombocytopenia and anemia: a case report

Background

Gaucher disease is an autosomal recessive inborn error of metabolism that causes disorders of blood, bone, and central nervous system as well as hepatosplenomegaly. We present the case of a carrier of Gaucher disease with gestational thrombocytopenia and anemia that required blood transfusion therapy.

Case presentation

A 24-year-old Nepalese primipara was diagnosed with idiopathic thrombocytopenia at 12 weeks of gestation. Her platelet count had reduced to 30,000/µL at 21 weeks of gestation, and the hemoglobin content reduced to 7.6 g/dL at 27 weeks of gestation. As she did not respond to any medication, blood transfusion was performed. A female infant weighing 2677 g was delivered vaginally at 39 weeks of gestation. On the 78th day of puerperium, the platelet count of the mother recovered to 101,000/µL, and the hemoglobin content recovered to 12.5 g/dL. The infant had convulsions, respiratory depression, wheezing, systemic purpura, and exfoliation of the epidermis at birth. The infant was diagnosed with Gaucher disease at 37 days of age and passed away at 82 days of age. Subsequently, the parents were diagnosed as carriers of Gaucher disease.

Conclusion

As carriers of this disease do not usually show symptoms, it is imperative to provide information regarding disease management for future pregnancies.

An Analysis of the Serum Metabolomic Profile for the Radiomitigative Effect of the Thrombopoietin Receptor Agonist Romiplostim in Lethally Whole-Body-Irradiated Mice

The thrombopoietin receptor agonist romiplostim (RP) was recently approved by the US Food and Drug Administration for improving survival in patients acutely exposed to myelosuppressive doses of radiation. Our previous studies with mice have shown that RP administration after lethal irradiation not only completely rescues irradiated mice but also shows mitigative effects on their hematopoiesis and multiple organ injury, including that of the lung, bone marrow, small intestine, and liver. However, the mechanism by which RP functions as a radiomitigator remains unclear. In the present study, we applied a metabolomics approach, which has the ability to reflect the status of an organism directly and accurately, helping to elucidate the biology of treatment responses. Our results showed that the disruption of several metabolites and pathways in response to total body irradiation was partially corrected by RP administration. Notably, RP-corrected metabolites and pathways have been reported to be indicators of DNA damage and lung, bone marrow, small intestine, and liver injury. Taken together, the present findings suggested that the radiomitigative effect of RP is partially involved in the recovery of organ injury, and the identified metabolites may be a useful biomarker of the survival likelihood following radiation exposure.

Extreme Thrombocytosis in Refractory ITP Post-Splenectomy With Associated Fatal Thromboembolism

Thrombopoietin (TPO)-receptor agonists have heralded a paradigm shift in the treatment of refractory immune thrombocytopenia (ITP). Reactive thrombocytosis has been described as a secondary effect of such therapies. However, the phenomenon of extreme thrombocytosis with morphology mimicking a myeloproliferative neoplasm (MPN) followed by fatal thromboembolism is unusual in this setting. Caution is required in the diagnosis of refractory ITP as well as TPO-receptor agonist dosing in such cases.

Pharmacokinetics, Pharmacodynamics, Efficacy and Safety of a Romiplostim Biosimilar in Chronic Refractory Immune Thrombocytopenic Purpura (ITP) Patients

Romiplostim (Nplate®, Amgen Inc.) is an orphan drug approved for the treatment of chronic refractory immune thrombolytic purpura (ITP) in adult and pediatric patients. Limited availability of pharmacokinetic (PK) data and large inter- and intra-subject variability in PK and platelet response is a challenge in the clinical development of a romiplostim biosimilar. We compared pharmacokinetics (PK), pharmacodynamics (PD)/efficacy, and safety of a romiplostim biosimilar with Nplate in 24 patients with ITP following a single 3 μg/kg dose, and assessed efficacy of the romiplostim biosimilar at a titrated dose range of 1-5 μg/kg in 50 patients with ITP. The PK of the romiplostim biosimilar did not differ compared to the PK of Nplate, and PD/efficacy responses were similar between the products following the single dose. The romiplostim biosimilar showed historically comparable PD/efficacy with Nplate over 8 weeks when treated at the titrated dose range. It was well tolerated in both the studies.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12288-021-01431-y.

Risk of infection in adult patients with primary immune thrombocytopenia (ITP): a systematic review

INTRODUCTION

Primary immune thrombocytopenia (ITP) is a bleeding disorder characterized by autoimmune destruction and impaired production of platelets. Immunosuppressive drugs are the main treatment and may increase risk of infection.

AREAS COVERED

This systematic review included studies incorporating adult patients with primary ITP and infectious outcomes. Studies comparing risk of infection with the general population were included as primary and studies without this comparison were considered secondary. Three primary and 10 secondary studies were included. The main findings: 1-year adjusted relative-risk of infection was 4.5 (95% CI, 3.3-6.1) fold elevated compared to the general population. When comparing splenectomized with non-splenectomized ITP patients, the +1-year adjusted relative-risk of infection was 4.0 (95% CI, 2.8-5.6). The unadjusted 5-year mortality rate-ratio for infection-related deaths was 6.0 (95% CI, 3.0-11.8) in one study, and the hazard ratio was 2.4 (95% CI, 1.0-5.7) for fatal infections in another.

EXPERT OPINION

This review emphasizes that patients with ITP have increased risk of infection. Since ITP is a benign hematologic disease, it is important to assess the extent and causes of infection in the clinical care and considerations before initiating treatment. More homogeneous studies are needed on this topic.

Experts' review: the emerging roles of romiplostim in immune thrombocytopenia (ITP)

INTRODUCTION

The management of ITP has in recent years been transformed from reliance on immunosuppressants and splenectomy to targeted therapy with thrombopoietin receptor agonists (TPO-RA) that directly stimulate platelet production in the bone marrow. This has reduced the long-term infective complications and toxicities associated with the use of potent immunosuppressants and splenectomy. The welltolerated romiplostim, itself a novel drug construct called peptibody, has established itself, alongside other TPO-RA as the preferred 2nd line therapy in major international guidelines on treatment of ITP.

AREAS COVERED

This review summarizes the data from early licensing trials of romiplostim and discusses the real-world experience to date, the unexpected emerging data on treatment-free long-term remission achieved using TPO-RA, and the case for its early introduction in the therapeutic pathway. The emerging risk of thrombosis is also discussed.

EXPERT OPINION

The use of romiplostim and other TPO-RA will be increasingly brought forward in the management pathway of ITP with the prospect of modifying the long-term outcome of the disease by increasing sustained treatment-free remission. With the prospect of several new targeted therapies been introduced into clinical practice, TPO-RA will likely be a key component of future combination therapies for difficult cases.

A Review of Romiplostim Mechanism of Action and Clinical Applicability

Thrombocytopenia results from a variety of conditions, including radiation, chemotherapy, autoimmune disease, bone marrow disorders, pathologic conditions associated with surgical procedures, hematopoietic stem cell transplant (HSCT), and hematologic disorders associated with severe aplastic anemia. Immune thrombocytopenia (ITP) is caused by immune reactions that accelerate destruction and reduce production of platelets. Thrombopoietin (TPO) is a critical component of platelet production pathways, and TPO receptor agonists (TPO-RAs) are important for the management of ITP by increasing platelet production and reducing the need for other treatments. Romiplostim is a TPO-RA approved for use in patients with ITP in the United States, European Union, Australia, and several countries in Africa and Asia, as well as for use in patients with refractory aplastic anemia in Japan and Korea. Romiplostim binds to and activates the TPO receptor on megakaryocyte precursors, thus promoting cell proliferation and viability, resulting in increased platelet production. Through this mechanism, romiplostim reduces the need for other treatments and decreases bleeding events in patients with thrombocytopenia. In addition to its efficacy in ITP, studies have shown that romiplostim is effective in improving platelet counts in various settings, thereby highlighting the versatility of romiplostim. The efficacy of romiplostim in such disorders is currently under investigation. Here, we review the structure, mechanism, pharmacokinetics, and pharmacodynamics of romiplostim. We also summarize the clinical evidence supporting its use in ITP and other disorders that involve thrombocytopenia, including chemotherapy-induced thrombocytopenia, aplastic anemia, acute radiation syndrome, perisurgical thrombocytopenia, post-HSCT thrombocytopenia, and liver disease.

Predictors for and outcomes after bone marrow biopsy in Scandinavian patients with chronic immune thrombocytopenia

OBJECTIVES

To examine predictors for bone marrow biopsy (BMB) and the outcome following BMB in patients with chronic immune thrombocytopenia (cITP).

METHODS

We identified patients diagnosed with cITP during 2009-2017 and obtained information on BMB, cITP treatment and subsequent thrombotic events, hospitalized bleeding, hematological cancer, and death using data from population-based healthcare databases and medical records in Denmark, Norway, and Sweden.

RESULTS

Among 4471 adults (≥18 years) with cITP, 1683 (37.6%) underwent BMB before cITP diagnosis, while cumulative BMB incidence after cITP diagnosis date was 3.1% at 1 year and 7.5% at 5 years. Predictors of having a BMB after cITP diagnosis included older age, male sex, low baseline platelet count, splenectomy, and number of cITP treatments. Compared with patients without BMB, patients with BMB had higher rates of thrombotic events (1 year adjusted hazard ratio [HR] 1.53 [95% CI, 0.92-2.54]), hospitalized bleeding episodes (1 year adjusted HR 1.72 [95% CI, 1.15-2.58]), hematological cancer (1 year adjusted HR 35.26 [95% CI 17.67-70.34]), and all-cause mortality (1 year adjusted HR 1.97 [95% CI, 1.44-2.68]).

CONCLUSION

Patients who undergo BMB after cITP diagnosis represent a subset of patients with more severe disease and increased rates of complications as well as hematological malignancies.

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.

Clinical overview and practical considerations for optimizing romiplostim therapy in patients with immune thrombocytopenia

The fundamental treatment goal for patients with immune thrombocytopenia (ITP) is reduced or ameliorated bleeding. Although various treatment options exist for the management of ITP, recent advances have led to the approval of three thrombopoietin receptor agonists (TPO-RAs; romiplostim, eltrombopag, and avatrombopag) in the United States and European Union. Current treatment guidelines for ITP indicate that medical therapy is preferred over surgical therapy and support the use of TPO-RAs as early as 3 months after disease onset. More recent data are available on the use of romiplostim in patients who have had ITP for <1 year, and romiplostim is now indicated for the treatment of adults who have not responded adequately to initial treatment, as well as children aged ≥1 year who have had ITP for ≥6 months. Here we review the role of romiplostim in the management of ITP, with a focus on efficacy and safety data, emerging data on early use (beginning within 3 months of disease onset) and treatment-free remission, and practical considerations for optimal management of ITP.

Disease management of patients with immune thrombocytopenia-results of a representative retrospective survey in Germany

Clinical research has resulted in an improvement of treatment options for patients with immune thrombocytopenia (ITP) over the last years. However, only few data exist on the real-life management of patients with ITP. To expand the knowledge, a multicenter, national survey was undertaken in 26 hematology practices distributed all over Germany. All patients with a diagnosis of ITP were documented using questionnaires, irrespective of the diagnosis date over a period of 2 years. Overall, data of 1023 patients were evaluated with 56% of patients being older than 60 years. Seventy-nine percent of the patients had chronic (> 12 months), 16% persistent (> 3-12 months), and 5% newly diagnosed (0-3 months) ITP. In 61% of cases, the disease lasted 3 or more years before survey documentation started. Main strategies applied as first-line therapy consisted of steroids in 45% and a "watch and wait" approach in 41% of patients. During second- and third-line strategies, treatment with steroids decreased (36% and 28%, respectively), while treatment modalities such as TPO-RAs increased (19% and 26%, respectively). As expected, patients with a low platelet count and thus a higher risk for bleeding and mortality received treatment (esp. steroids) more frequently during first line than those with a higher platelet count. Up to a third of patients were treated with steroids for more than a year. Overall, our study provides a cross-section overview about the current therapeutic treatment landscape in German ITP patients. The results will help to improve therapeutic management of ITP patients.

Practical guidance for the management of adults with immune thrombocytopenia during the COVID-19 pandemic

This document aims to provide practical guidance for the assessment and management of patients with thrombocytopenia, with a particular focus on immune thrombocytopenia (ITP), during the COVID‐19 pandemic. The intention is to support clinicians and, although recommendations have been provided, it is not a formal guideline. Nor is there sufficient evidence base to conclude that alternative approaches to treatment are incorrect. Instead, it is a consensus written by clinicians with an interest in ITP or coagulation disorders and reviewed by members of the UK ITP forum.

The role of romiplostim for pediatric patients with immune thrombocytopenia

The thrombopoietin receptor agonists (TPO-RAs) are a class of platelet growth factors used to treat immune thrombocytopenia (ITP) in children and adults. Romiplostim is a peptide TPO-RA approved for over a decade to treat adults with ITP but was just recently US Food and Drug Administration approved to manage ITP in children 1 year of age and older who have had an inadequate response to corticosteroids, intravenous immunoglobulin, or splenectomy. Like the small molecule TPO-RA eltrombopag, romiplostim offers a high clinical response rate in pediatric patients with ITP, but requires use over an extended, and possibly indefinite, duration. This review is a critical appraisal of the role of romiplostim in pediatric ITP, discussing the safety and efficacy of this agent in clinical trials of children and adults and defining the patients most likely to benefit from romiplostim treatment. The treating hematologist is additionally provided guidance with treatment goals, dosing strategies, toxicity management, and indications for discontinuation.

Romiplostim for the Treatment of Immune Thrombocytopenia: Spotlight on Patient Acceptability and Ease of Use

Immune thrombocytopenia (ITP) is an immune-mediated disorder resulting in platelet destruction and subsequent thrombocytopenia. Bleeding symptoms range from mild cutaneous bleeding to life-threatening hemorrhage. Romiplostim, a peptide-antibody fusion product, is a thrombopoietin receptor agonist (TPO-RA) indicated for use in patients with ITP. Romiplostim is US Food and Drug Administration (FDA) approved in children ≥1 year of age with ITP of >6 months' duration who have had an inadequate response to first-line therapies or splenectomy. FDA approval in adults with chronic ITP was expanded in October 2019 to include adults with newly diagnosed (<3 months' duration) and persistent (3-12 months' duration) ITP who demonstrated an inadequate response to first-line therapies, including corticosteroids and immunoglobulins, or splenectomy. The newly published 2019 American Society of Hematology ITP Guidelines place TPO-RAs, including romiplostim, as second-line therapies in both children and adults. Here, we review the use of romiplostim as second-line therapy with a spotlight on health-related quality of life, ease of use, and patient preference.

Treating ITP: What are the options in the era of new guidelines and new drugs?

Primary immune thrombocytopenia (ITP) is an autoimmune disease characterized by isolated thrombocytopenia. Treating ITP may be challenging since different treatment modalities are available. While choosing the suitable option for every patient, a physician should take into account both patient's medical characteristics and wishes. The first line treatment options include: corticosteroids, intravenous immunoglobulins and intravenous anti-D immunoglobulin. Second line treatment options comprise medical (thrombopoietin receptor agonists, rituximab, fostamatinib, azathioprine, cyclophosphamide, cyclosporin A, hydroxychloroquine, mycophenolate mofetil, danazol, dapsone, vinca-alcaloids) and surgical (splenectomy) approach. However, there are some treatment gaps which remain uncovered with existing treatment modalities. Therefore, development of novel therapeutic strategies is required. The aim of this review is to provide an illustrative overview of novel treatments for adult ITP.

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.

Thrombocytopenia in pregnancy: Diagnosis and approach to management

Thrombocytopenia during pregnancy presents unique challenges for the hematologist. Obstetricians generally manage many of the pregnancy-specific etiologies, ranging from the benign (gestational thrombocytopenia) to the life-threatening (preeclampsia; hemolysis, elevated liver enzymes and low platelets syndrome; and acute fatty liver of pregnancy). However, hematologists may be consulted for atypical and severe presentations and to help manage non-pregnancy specific etiologies, including immune thrombocytopenia, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome and antiphospholipid syndrome, among others, in which maternal and fetal risks must be considered. This review provides a general approach to the diagnosis and management of thrombocytopenia in pregnancy for the consulting hematologist.

Romiplostim-related myelofibrosis in refractory primary immune thrombocytopenia: A Case report

RATIONALE

Primary immune thrombocytopenia (ITP) is an immune-mediated disease that is defined as increased platelet destruction and impaired platelet production. Treatment is recommended for highly selected patients, the standard regimen includes glucocorticoid, intravenous immunoglobulin (IVIG). The recombinant thrombopoietin (TPO) receptor agonists, romiplostim, stimulate platelet production and have approved for glucocorticoid or IVIG, splenectomy-refractory chronic ITP patients.

PATIENT CONCERNS

A patient has been diagnosed with ITP, reftractory to steroid, IVIG, splenectomy, danazol, and cyclosporine. The patient received romiplostim to normalize his platelet count, however, over the course of the following year, his platelet counts progressively decreased despite increasing the romiplostim dosing.

DIAGNOSES

A peripheral blood smear showed a severe leukoerythroblastic reaction and bone marrow biopsy demonstrated myelofibrosis due to romiplostim.

OUTCOMES

Since this diagnosis, romiplostim was discontinued for a while, after 3 months, romiplostim was re-administered to improve thrombocytopenia. His platelet count recovered to 70,000/mm after the administration of romiplostim at 2 μg/kg, and he did not experience complications for 6 months.

LESSONS

This report represents the first evidence of romiplostim-induced myelofibrosis, which was associated with increased levels of bone marrow reticulin and Masson trichrome staining.

Thrombopoietin receptor agonists: ten years later

The two thrombopoietin receptor agonists (TPO-RA), eltrombopag and romiplostim, were licensed in the US for treatment of immune thrombocytopenia (ITP) in 2008 and, since then, their use has progressively increased around the world; they are currently used in more than 100 countries. The six largest randomized controlled trials conducted in ITP have used one of these two agents. All studies have demonstrated a platelet response rate between 50-90%, depending on the criteria used, with good safety and tolerability. TPO-RA were shown to be effective in reducing bleeding and the need for concomitant or rescue medication. Many other investigations of their mechanism of effect, prospective and retrospective trials, and studies focusing on toxicity have been performed widening our knowledge of these two agents. Initial concerns on issues such as myelofibrosis have not been confirmed. Only a small number of patients develop moderate-severe reticulin fibrosis and/or collagen fibrosis; however, these are usually reversed after discontinuation of TPO-RA. Studies indicate, however, that TPO-RA may increase the risk of venous thromboembolism. Both TPO-RA are currently approved in patients with chronic ITP aged >1-year who are refractory to at least one other treatment. Eltrombopag has acquired two additional indications: severe aplastic anemia refractory to first-line treatment and hepatitis C patients undergoing treatment with interferon-ribavirin. Despite these wide-ranging studies, important questions still need to be answered. This summary review on TPO-RA will summarize what is known regarding efficacy in ITP, evaluate safety concerns in more depth, and focus on the questions that remain.

Long-term treatment with romiplostim and treatment-free platelet responses in children with chronic immune thrombocytopenia

Children with immune thrombocytopenia for ≥6 months completing a romiplostim study received weekly subcutaneous romiplostim (1-10 μg/kg targeting platelet counts of 50-200×10⁹/L) in this extension to examine romiplostim’s long-term safety and efficacy. Sixty-five children received romiplostim for a median of 2.6 years (range: 0.1-7.0 years). Median baseline age was 11 years (range: 3-18 years) and platelet count was 28×10⁹/L (range: 2-458×10⁹/L). No patient discontinued treatment for an adverse event. Median average weekly dose was 4.8 mg/kg (range: 0.1-10 mg/kg); median platelet counts remained >50×10⁹/L, starting at week 2. Nearly all patients (94%) had ≥1 platelet response (≥50×10⁹/L, no rescue medication in the previous 4 weeks), 72% had responded at ≥75% of visits, and 58% had responded at ≥90% of visits. Treatment-free response (platelets ≥50×10⁹/L ≥24 weeks without immune thrombocytopenia treatment) was seen in 15 of 65 patients while withholding romiplostim doses. At onset of treatment-free response, the nine girls and six boys had a median immune thrombocytopenia duration of four years (range: 1-12 years) and had received romiplostim for two years (range: 1-6 years). At last observation, treatment-free responses lasted for a median of one year (range: 0.4-2.1 years), with 14 of 15 patients still in treatment-free response. Younger age at first dose and platelet count >200×10⁹/L in the first four weeks were associated with treatment-free responses. In this 7-year open-label extension, three-quarters of the patients responded ≥75% of the time, and romiplostim was well tolerated, with no substantial treatment-related adverse events. Importantly, 23% of children maintained treatment-free platelet responses while withholding romiplostim and all other immune thrombocytopenia medications for ≥6 months. (Registered at clinicaltrials.gov identifier: 01071954)

Protective Effect of the c-mpl Agonist Romiplostim on Megakaryocytopoiesis of Human CD34+ Hematopoietic Progenitor Cells Exposed to Ionizing Radiation

A thrombopoiesis-stimulating protein, the myeloproliferative leukemia virus protooncogene (Mpl) ligand romiplostim (RP), is currently approved as a therapeutic agent for idiopathic thrombocytopenic purpura in many countries. Although the action of the initial MPL ligand thrombopoietin (TPO) on human megakaryocytic regeneration from irradiated human hematopoietic stem cells has been examined, there are few reports on the action of RP. In the present study, freshly prepared nonirradiated and 2-Gy X-irradiated human CD34 positive (CD34⁺) cells from placental umbilical cord blood were cultured with a combination of RP and various cytokines. As a result, the effect of RP on cell proliferation of nonirradiated CD34⁺ cells was found to be comparable to that of TPO. However, the stimulating activity of RP on megakaryocytic progenitor-derived colony formation was markedly lower compared with TPO. Regarding the action of RP with various cytokines, the present results showed that a combination of RP with interleukin-3 (IL-3) or IL-3 plus stem cell factor (SCF) showed a high regenerative effect on cell proliferation, megakaryopoiesis, thrombopoiesis, and megakaryocyte colony formation from X-irradiated CD34⁺ cells. The present study showed that human recombinant RP has potential effects on human megakaryocytic regeneration from X-irradiated human CD34⁺ cells and synergistically acts with IL-3 and IL-3 plus SCF, just as observed with TPO.