A randomized, double-blind study of romiplostim to determine its safety and efficacy in children with immune thrombocytopenia

Management of thrombocytopenia due to liver cirrhosis: A review

Thrombocytopenia is a common complication in liver disease and can adversely affect the treatment of liver cirrhosis, limiting the ability to administer therapy and delaying planned surgical/diagnostic procedures because of an increased risk of bleeding. Multiple factors, including splenic sequestration, reduced activity of the hematopoietic growth factor thrombopoietin, bone marrow suppression by chronic hepatitis C virus infection and anti-cancer agents, and antiviral treatment with interferon-based therapy, can contribute to the development of thrombocytopenia in cirrhotic patients. Of these factors, the major mechanisms for thrombocytopenia in liver cirrhosis are (1) platelet sequestration in the spleen; and (2) decreased production of thrombopoietin in the liver. Several treatment options, including platelet transfusion, interventional partial splenic embolization, and surgical splenectomy, are now available for severe thrombocytopenia in cirrhotic patients. Although thrombopoietin agonists and targeted agents are alternative tools for noninvasively treating thrombocytopenia due to liver cirrhosis, their ability to improve thrombocytopenia in cirrhotic patients is under investigation in clinical trials. In this review, we propose a treatment approach to thrombocytopenia according to our novel concept of splenic volume, and we describe the current management of thrombocytopenia due to liver cirrhosis.

Milestones in understanding platelet production: a historical overview

The discovery of thrombopoietin (TPO, also termed THPO) in 1994 was a major achievement in understanding the regulation of platelet production. In prior decades, physiological studies had demonstrated that platelets were produced from bone marrow megakaryocytes and that the megakaryocytes responded to thrombocytopenia by increasing their number, size and DNA ploidy. In 1958, it was proposed that a 'thrombopoietin' must exist that regulated this interaction between the circulating platelet mass and the bone marrow megakaryocytes. After over three decades of effort, TPO was finally purified by five independent laboratories. TPO stimulated megakaryocyte colony-forming cell growth and increased the number, size and ploidy of megakaryocytes. When the genes for TPO or TPO receptor were eliminated in mice, megakaryocytes grew and platelets were made, but at 15% of their normal number. A first generation of recombinant human (rh) TPO molecules [rhTPO and pegylated recombinant human megakaryocyte growth and development factor (PEG-rhMGDF)] rapidly entered clinical trials in 1995 and increased platelet counts in humans undergoing non-myeloablative chemotherapy but not in those undergoing stem cell transplantation. Antibodies developed against PEG-rhMGDF and development of these recombinant thrombopoietins ended. A second generation of TPO receptor agonists (romiplostim and eltrombopag) was then developed. Neither of these TPO receptor agonists demonstrated any significant untoward effects and both are now licensed in many countries for the treatment of immune thrombocytopenia. This review describes the significant experiments that have surrounded the discovery of TPO and its clinical development.

Clinical practice: immune thrombocytopenia in paediatrics

Immune thrombocytopenia (ITP) is a disease affecting both children and adults. It is defined as acquired isolated thrombocytopenia caused by the autoimmune production of anti-platelet antibodies. Childhood ITP most frequently occurs in young children who have been previously well, although a viral respiratory tract infection often precedes thrombocytopenia. A benign and self-limiting course is common, but major bleeding complications such as intracranial haemorrhage may occur. Yet one cannot predict which child will have a prolonged course of thrombocytopenia and who will develop an intracranial haemorrhage. In children without atypical characteristics, only minimal diagnostic investigations are needed, and most paediatric ITP patients do not need platelet-enhancing therapy even though various treatment options are available. A "watch and wait" strategy should be considered in paediatric patients with mild disease. Steroids, intravenous immunoglobulin G or anti-D immunoglobulin are the current first-line therapeutic measures for children at risk for severe bleeding. When life-threatening bleeding occurs, a combination of therapies is needed. In this review, we summarise the current knowledge on primary ITP in children and adolescents.

Immune thrombocytopenia

Immune thrombocytopenia (ITP) is a common hematologic disorder characterized by isolated thrombocytopenia. ITP presents as a primary or a secondary form. ITP may affect individuals of all ages, with peaks during childhood and in the elderly, in whom the age-specific incidence of ITP is greatest. Bleeding is the most common clinical manifestation of ITP. The pathogenesis of ITP is complex, involving alterations in humoral and cellular immunity. Corticosteroids remain the most common first line therapy for ITP. This article summarizes the classification and diagnosis of primary and secondary ITP, as well as the pathogenesis and options for treatment.

Diagnosis and management of autoimmune cytopenias in childhood

The diagnosis and management of children with autoimmune cytopenias can be challenging. Children can present with immune-mediated destruction of a single-cell lineage or multiple cell lineages, including platelets (immune thrombocytopenia [ITP]), erythrocytes (autoimmune hemolytic anemia), and neutrophils (autoimmune neutropenia). Immune-mediated destruction can be primary or secondary to a comorbid immunodeficiency, malignancy, rheumatologic condition, or lymphoproliferative disorder. Treatment options generally consist of nonspecific immune suppression or modulation. This nonspecific approach is changing as recent insights into disease biology have led to targeted therapies, including the use of thrombopoietin mimetics in ITP and sirolimus for cytopenias associated with autoimmune lymphoproliferative syndrome.

Pharmacokinetics of Peptide-Fc fusion proteins

Peptide-Fc fusion proteins (or peptibodies) are chimeric proteins generated by fusing a biologically active peptide with the Fc-domain of immunoglobulin G. In this review, we describe recent studies that have evaluated the absorption, distribution, metabolism, and excretion characteristics of peptibodies. Key features of the pharmacokinetics of peptibodies include their extended half-life due to recycling by the neonatal Fc receptor (FcRn), a substantial contribution by renal excretion to total clearance and, for certain peptibodies, target-mediated drug disposition. The prolonged half-life of peptibodies permits less-frequent dose administration compared with small therapeutic peptides, thereby supporting patient convenience and compliance. Hence, a considerable number of peptibodies are currently in preclinical and clinical development. Investigation of the metabolism (biotransformation) of biologics is an evolving area of research: ligand-binding mass spectrometry techniques have been employed for the characterization of the peptibody romiplostim, providing a new approach to evaluation of the degradation products of biologics. Pharmacokinetic/pharmacodynamic modeling and simulation techniques have been used to predict the pharmacokinetics of peptibodies which can inform clinical decision-making, particularly selection of dosing regimens. This integrated review highlights the distinct pharmacokinetic characteristics of peptibodies and their influence on the drug development process for this emerging family of therapeutics.

Romiplostim in children with chronic immune thrombocytopenia (ITP): the French experience

A minority of children with chronic immune thrombocytopenia (ITP) require therapeutic intervention to prevent haemorrhagic risk. This retrospective national study evaluated romiplostim in childhood non-responsive or refractory chronic ITP. Between 2009 and 2012, 10 patients whose Buchanan score was 3-4 were treated with romiplostim. The median duration of thrombocytopenia was 1·9 years (0·8-15). The median duration of romiplostim treatment was 9 months (3-36). A response was observed in 5/10 patients (one complete, four partial). No serious adverse effect was noticed. The long-term benefit/risk balance of this innovative treatment is currently recorded by Centre de Référence National des Cytopénies Auto-immunes de l'Enfant.

The biology of thrombopoietin and thrombopoietin receptor agonists

Thrombopoietin (TPO) is the major physiological regulator of platelet production. TPO binds the TPO receptor, activates JAK and STAT pathways, thus stimulating megakaryocyte growth and platelet production. There is no "sensor" of the platelet count; rather TPO is produced in the liver at a constant rate and cleared by TPO receptors on platelets. TPO levels are inversely proportional to the rate of platelet production. Early recombinant TPO molecules were potent stimulators of platelet production and increased platelets in patients with immune thrombocytopenia, chemotherapy-induced thrombocytopenia, myelodysplastic syndromes and platelet apheresis donors. Neutralizing antibodies formed against one recombinant protein and ended their development. A second generation of TPO receptor agonists, romiplostim and eltrombopag, has been developed. Romiplostim is an IgG heavy chain into which four TPO agonist peptides have been inserted. Eltrombopag is an oral small molecule. These activate the TPO receptor by different mechanisms to increase megakaryocyte growth and platelet production. After administration of either to healthy volunteers, there is a delay of 5 days before the platelet count rises and subsequently reaches a peak after 12-14 days. Both have been highly effective in treating ITP and hepatitis C thrombocytopenia. Studies in a wide variety of other thrombocytopenic conditions are underway.

Successful treatment of refractory immune thrombocytopenia with rituximab in a 10-week-old infant

Immune thrombocytopenic purpura (ITP) that is unresponsive to conventional treatment is uncommon. In this situation, additional therapeutic options are limited and management is challenging. We describe the case of a 10-week-old infant that developed life-threatening ITP that was unresponsive to immunoglobulin and corticosteroids that was successfully managed with the monoclonal antibody rituximab. The literature on the use of rituximab in nonresponsive ITP is reviewed.

Advances in megakaryocytopoiesis and thrombopoiesis: from bench to bedside

Megakaryocytopoiesis involves the commitment of haematopoietic stem cells, proliferation and terminal differentiation of megakaryocytic progenitors (MK-p) and maturation of megakaryocytes (MKs) to produce functional platelets. This complex process occurs in specialized niches in the bone marrow where MKs align adjacent to vascular endothelial cells, form proplatelet projections and release platelets into the circulation. Thrombopoietin (THPO, TPO) is the primary growth factor for the MK lineage and necessary at all stages of development. THPO is constitutively produced in the liver, and binds to MPL (c-Mpl) receptor on platelets and MKs. This activates a cascade of signalling molecules, which induce transcription factors to drive MK development and thrombopoiesis. Decreased turnover rate and platelet number result in increased levels of free THPO, which induces a concentration-dependent compensatory response of marrow-MKs to enhance platelet production. Newly developed thrombopoietic agents operating via MPL receptor facilitate platelet production in thrombocytopenic states, primarily immune thrombocytopenia. Other drugs are available for attenuating malignant thrombocytosis. Herein, we review the regulation of megakaryocytopoiesis and platelet production in normal and disease states, and the innovative drugs and therapeutic modalities to stimulate or decrease thrombopoiesis.

Sustained remissions of immune thrombocytopenia associated with the use of thrombopoietin receptor agonists

BACKGROUND

Thrombopoietin receptor agonists (TRAs) are effective treatments for immune thrombocytopenia (ITP). However, continuous therapy is generally required to maintain platelet (PLT) count responses.

STUDY DESIGN AND METHODS

In this case series, we describe ITP patients from our practice who achieved durable responses to the TRAs romiplostim and eltrombopag. Patients were classified as having a definite TRA-induced remission if PLT counts increased above 100 × 10(9) /L after TRA treatment and remained above 100 × 10(9) /L even after the medication was discontinued; or a possible TRA-induced remission if PLT counts increased above 100 × 10(9) /L, remained elevated for at least 3 months after the medication was discontinued, but a subsequent relapse occurred or the effect of other disease-modifying therapies could not be excluded.

RESULTS

Of 31 patients with chronic ITP treated with TRAs in our practice, nine patients achieved a PLT count response with either romiplostim (n = 6) or eltrombopag (n = 3) that was maintained even after the medications were discontinued. Three patients met criteria for a definite TRA-induced remission, each after exposure to romiplostim. Patients had ITP for a median of 7.8 years and had failed a median of four prior therapies including eight patients who had a splenectomy. We documented a progressive decline in anti-glycoprotein IIbIIIa PLT autoantibodies in one patient while on treatment.

CONCLUSION

Some patients with ITP can achieve sustained PLT count responses after the use of TRAs. This observation raises the possibility that these agents may restore immune tolerance to PLT antigens in some patients and supports the practice of down titrating the dose.

High doses of romiplostim induce proliferation and reduce proplatelet formation by human megakaryocytes

Background

Romiplostim (AMG531) is a Thrombopoietin (TPO) receptor agonist with no homology with the endogenous TPO that has been used to treat patients affected by immune thrombocytopenia (ITP). Despite the use of TPO mimetics in the clinical practice, the mechanisms underlying their impact on megakaryocyte function is still unknown.

Methodology/Principal Findings

In this project we took advantage of an in vitro human model, that we have established in our laboratory for long time to study megakaryocyte development from human cord blood-derived progenitor cells, and we demonstrated that increasing doses of AMG531 (100 to 2000 ng/mL) determine a progressive increase of megakaryocyte proliferation with a parallel decrease in megakaryocyte ploidy and capacity of extending proplatelets. Most importantly, these differences in megakaryocyte function seemed to be correlated to modulation of AKT phosphorylation.

Conclusions/Significance

Overall our results shed new light on the mechanisms and on the relevance of dosage related to AMG531 impact on megakaryocyte function.

Current management of immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune-mediated condition that results from antibody-mediated destruction of platelets and impaired megakaryocyte platelet production. ITP patients exhibit severe thrombocytopenia and are at risk for significant hemorrhage. Few randomized trials exist to guide management of patients with ITP. Ultimately, each patient requires an individualized treatment plan that takes into consideration the platelet count, bleeding symptoms, health-related quality of life, and medication side effects. This article provides an up-to-date review of management strategies drawing on links between the expanding amounts of clinical trial data and associated biology studies to enhance understanding of the disease heterogeneity with regard to the complex pathogenesis and response to treatment.

Successful treatment of severe newly diagnosed immune thrombocytopenia involving an alveolar hemorrhage with combination therapy consisting of romiplostim, rituximab and vincristine

A 51-year-old man was admitted due to a severe bleeding tendency. After he was diagnosed with immune thrombocytopenia (ITP), several therapies, including steroids, steroid pulse, vincristine and rituximab, were administered; however, the patient's bleeding symptoms were not sufficiently controllable with these treatments. Subsequently, a diffuse alveolar hemorrhage was observed. Treatment with a thrombopoietin receptor agonist, romiplostim, was initiated to prevent lethal hemorrhaging, although the efficacy of thrombopoietic receptor agonists in such emergency situations has not been elucidated. The initiation of romiplostim achieved prompt remission in platelets. This case suggests that combination therapy with romiplostim, rituximab and vincristine is effective in cases of newly diagnosed severe therapy-resistant ITP.

Positioning new treatments in the management of immune thrombocytopenia

Immune thrombocytopenia (ITP) is a syndrome characterized by low platelet counts and an increased risk of bleeding. For most children, ITP is a self-limiting disease; however, for some children and most adults, thrombocytopenia can become chronic. Newer therapies for ITP include rituximab and thrombopoietin (TPO) receptor agonists. Rituximab is a useful second-line therapy and may be splenectomy-sparing. Thrombopoeitin receptor agonists have demonstrated large treatment effects with respect to increasing platelet levels; however, they require maintenance dosing. This review summarizes how these new agents might be positioned in the management of patients with chronic ITP.

Characteristics and outcome of early-onset, severe forms of Wiskott-Aldrich syndrome

On the basis of a nationwide database of 160 patients with Wiskott-Aldrich syndrome (WAS), we identified a subset of infants who were significantly more likely to be attributed with an Ochs score of 5 before the age of 2 (n = 26 of 47 [55%], P = 2.8 × 10(−7)). A retrospective analysis revealed that these patients often had severe refractory thrombocytopenia (n = 13), autoimmune hemolytic anemia (n = 15), and vasculitis (n = 6). One patient had developed 2 distinct cancers. Hemizygous mutations predictive of the absence of WAS protein were identified in 19 of the 24 tested patients, and the absence of WAS protein was confirmed in all 10 investigated cases. Allogeneic hematopoietic stem cell transplantation (HSCT) was found to be a curative treatment with a relatively good prognosis because it was successful in 17 of 22 patients. Nevertheless, 3 patients experienced significant disease sequelae and 4 patients died before HSCT. Therefore, the present study identifies a distinct subgroup of WAS patients with early-onset, life-threatening manifestations. We suggest that HSCT is a curative strategy in this subgroup of patients and should be performed as early in life as possible, even when a fully matched donor is lacking.

Childhood immune thrombocytopenia: role of rituximab, recombinant thrombopoietin, and other new therapeutics

Childhood immune thrombocytopenia (ITP) is often considered a benign hematologic disorder. However, 30% of affected children will have a prolonged course and 5%-10% will develop chronic severe refractory disease. Until recently, the only proven therapeutic option for chronic severe ITP was splenectomy, but newer alternatives are now being studied. However, because immunosuppressive agents such as rituximab are not approved for use in ITP and the thrombopoietin receptor agonists are not yet approved in children, the decision to use alternatives to splenectomy needs to be considered carefully. This review describes the factors that should affect decisions to treat ITP at diagnosis and compares the options for the occasional child in whom ITP does not resolve within the first year.

Thrombopoietin-receptor agonists

PURPOSE OF REVIEW

Thrombopoietin-receptor agonists (TPO-RAs) have been approved for use in immune thrombocytopenia (ITP) after showing safety and efficacy. There is increasing interest to expand the role of TPO-RAs, both in ITP as well as in other thrombocytopenic disorders.

RECENT FINDINGS

In ITP, more studies are providing evidence of TPO-RA efficacy and safety, as well as their applicability to various patient groups, including children. Use of TPO-RAs in hepatitis C has shown early success in allowing treatments in patients who would otherwise be excluded due to thrombocytopenia. Use in congenital thrombocytopenias has also shown early success. The use of TPO-RAs in myelodysplastic syndrome (MDS) is questionable after reports of increasing blasts and leukemic transformation, whereas in other chemotherapy-induced thrombocytopenias (C-ITs) reports are few. Bone marrow fibrosis remains an area of active study, although the data to date suggest this is seen in a small minority of patients, and is reversible and of questionable clinical relevance. Thrombotic complications are also an area of concern and need further close follow-up.

SUMMARY

The use of TPO-RAs continues to grow as more evidence of safety and efficacy is found. More studies are needed to determine their utility in other diseases as well as to better characterize adverse events observed to date.

Immune thrombocytopenic purpura: historical perspective, current status, recent advances and future directions

Immune thrombocytopenic purpura (ITP) has witnessed many changes and updates over the past decade. The definitions of disease subtypes, course and response to treatment have all been standardized recently. Consequent to the lack of an international consensus management guideline, wide variations exist in treatment practice. This is now being addressed to an extent by the much awaited ITP International Working Group 2010 recommendations. The pathophysiologic mechanisms have been unfolded at cellular, molecular and humoral levels. As a result, many recent advances have taken place in the management of this disorder. This review revisits the history of evolution of ITP, summarizes the current recommendations for management and lists the recent advances and future prospects in this field.

Spontaneous improvement of chronic immune thrombocytopenia in children: experience of 56 patients at a single institute

Spontaneous improvement (SI) occurs more frequently in children with chronic immune thrombocytopenia (cITP) than in adults. It is generally accepted that, with the exception of splenectomy, conventional medical approaches for cITP do not change the natural course of the disease. Previous studies on pediatric cITP have reported prognostic factors associated with SI; however, it is important to know when such improvement occurs to enable optimal treatment strategies for cITP. Here, we report results of retrospective analysis of 56 consecutive pediatric patients with cITP at our institution. The median follow-up period after ITP diagnosis was 67 months (11-185 months). Of the 44 patients without splenectomy, 17 achieved SI at a median age of 8.5 years (2.3-16.5 years). The estimated incidence of SI was 24.6 ± 6.0 % at 36 months. In 16 of the 17 patients with SI, the recovery was achieved within 18 months from diagnosis, or at an age of less than 10 years, whereas among the 24 who did not achieve spontaneous improvement both at "an age of 10 years or more" and at "18 months or more from ITP diagnosis", only one recovered spontaneously. A treatment decision tree, including the indication for splenectomy, should be considered based on this watershed point.

Bleeding and mortality outcomes in ITP clinical trials: a review of thrombopoietin mimetics data

Patients with ITP may have severe thrombocytopenia, putting them at risk for serious bleeding. ITP trials of new treatments must allow use of standard-of-care therapies to prevent serious bleeding. Thrombopoietin mimetic trials used platelet counts and rescue/concomitant medication use as endpoints. These trials were of insufficient size and duration to measure mortality or serious bleeding, which are infrequent with appropriate treatment. A recent Cochrane review criticized the thrombopoietin mimetic registrational trials for inadequately assessing bleeding and survival. We discuss how these endpoints are difficult to measure in clinical trials designed to improve platelet counts and minimize bleeding, in accordance with ethical trial design.

An analysis of outcomes and treatment costs for children undergoing splenectomy for chronic immune thrombocytopenia purpura

PURPOSE

Indications and timing for splenectomy in pediatric chronic immune thrombocytopenic purpura (cITP) are controversial because of high spontaneous remission rates and concern for overwhelming postsplenectomy infection. The objective of this study was to assess the risks, costs, and benefits of medical and surgical intervention for children with cITP.

METHODS

After receiving institutional review board approval, medical records for all children with cITP who underwent splenectomy from 2002 through 2009 were retrospectively reviewed (n = 22). Preoperative and postoperative data were collected. Medical and surgical costs were calculated based on pharmacy charges per dose and hospital charges, respectively.

RESULTS

The median age at diagnosis was 11 years (range, 3-16 years). Medical management included steroids (n = 21), intravenous gamma globulin (n = 19), anti-D antibody (n = 19), or a combination of these therapies (n = 22). Nineteen patients (86%) reported side effects from medical therapy. Median age at splenectomy was 13 years (range, 6-18 years), and time to surgery was 23 months from diagnosis (range, 6-104 months). Splenectomy increased platelet counts in all children from a median of 25,500 to 380,000 postoperatively (P < .0001). One child experienced overwhelming postsplenectomy infection after a dog bite (n = 1). At the last follow-up (15 months; range, 1-79 months), 19 patients (86%) were asymptomatic with platelet counts greater than 50,000. Of the 3 children with persistent thrombocytopenia, 2 were diagnosed with secondary cITP. Median cost of splenectomy was significantly less than the cost of medical therapy ($20,803 vs $146,284; P < .0002).

CONCLUSION

Earlier surgical consultation for children with cITP may be justified given the high success rate and low morbidity, particularly given the significant complication rate and cost of continued medical treatment.

Management of children and adolescents with primary immune thrombocytopenia: controversies and solutions

The management including diagnostic procedures, prophylaxis, treatment and follow-up of patients with primary immune thrombocytopenia (ITP) in childhood is controversial due to limited clinical data, difficulties in the estimation of individual bleeding risk and heterogeneity of pathophysiology potentially causing various treatment responses. Advances in the management of children include increased international collaborations, improved quality of diagnosis and treatment, increased clinical data, refinement of consensus statements where clinical evidence is absent, new drugs and last but not least establishment of watch-and-wait strategies. The Intercontinental Cooperative ITP Study Group promotes international collaboration since more than 10 years based on a worldwide network and experience in registries. Future considerations include concentration of available resources, strengthening international collaboration, focusing on most important scientific and clinical questions, such as identification of the subgroup of patients that benefits most from prophylactic platelet-enhancing treatments and investigation of treatment endpoints other than concepts solely based on the platelet count, including bleeding symptoms, health-related quality of life and economical aspects of treatments.

Duration and morbidity of chronic immune thrombocytopenic purpura in children: five-year follow-up of a Nordic cohort

AIM

To describe the clinical course, morbidity and platelet recovery in an unselected Nordic cohort of children with chronic Immune Thrombocytopenic Purpura (ITP).

METHODS

Prospective 5-year follow-up of 96 children with ITP lasting more than 6 months, with reporting of hospital admissions, severity of bleeding episodes and stabilization of platelet counts above 20, 50 and 150 × 10(9) /L.

RESULTS

The estimated 5-year recovery rate was 52%; exclusion of 12 splenectomized children did not change the estimate. Events eliciting admission to hospital occurred in 39 (41%). Major haemorrhages occurred in eight children (8%), including a nonfatal intracranial haemorrhage in one child (1%). The overall admission rate was 0.4/year of thrombocytopenia, decreasing during follow-up as thrombocytopenia converted to milder degrees. Early recovery within 2 years of diagnosis occurred in 35%, was associated with low morbidity and was more likely in young children with abrupt onset of symptoms.

CONCLUSION

In a Nordic cohort of children with chronic ITP, one half had recovered 5 years after diagnosis, more than half never required hospitalization and <10% experienced serious bleeding episodes, always with a platelet count <20 × 10(9) /L. Aggressive management can be restricted to the minority of children with continuing severe thrombocytopenia and frequent, clinically significant bleeding events.

Romiplostim: a review of its use in immune thrombocytopenia

Romiplostim (Nplate®) is an Fc-peptide fusion protein (peptibody) that acts as a thrombopoietin receptor agonist; it has no amino acid sequence homology with endogenous thrombopoietin. This article reviews the clinical efficacy and tolerability of subcutaneous romiplostim in adults with immune thrombocytopenia (ITP), as well as summarizing its pharmacological properties. The efficacy of 12 or 24 weeks' therapy with subcutaneous romiplostim was compared with that of placebo in patients with ITP in three randomized, double-blind, multicentre, phase III trials. In the two 24-week trials, the durable platelet response rate (primary endpoint) was significantly higher with romiplostim than with placebo in both splenectomized and nonsplenectomized patients. In addition, the majority of romiplostim recipients were able to discontinue or reduce their concurrent ITP therapy, and romiplostim improved health-related quality of life (HR-QOL). In the 12-week trial in splenectomized or nonsplenectomized Japanese patients with ITP, the median number of weeks with a platelet response (primary endpoint) was significantly higher with romiplostim than with placebo. Two extension studies (with median durations of romiplostim treatment of 78 and 100 weeks) demonstrated that long-term therapy with romiplostim maintained platelet counts in the target range in patients with ITP. In a randomized, open-label, multicentre, 52-week, phase IIIb trial, romiplostim was more effective than the medical standard of care in nonsplenectomized patients with ITP who had received at least one prior ITP treatment. Significantly fewer patients receiving romiplostim versus the medical standard of care experienced treatment failure or required splenectomy (co-primary endpoints), and clinically meaningful improvements from baseline in HR-QOL scores were seen with romiplostim. Subcutaneous romiplostim was generally well tolerated in patients with ITP; in short-term trials, the majority of adverse events were of mild to moderate severity and appeared to be related to the underlying thrombocytopenia. The incidence of bleeding events of at least grade 3 severity did not significantly differ between romiplostim and placebo recipients, and was significantly lower with romiplostim than with the medical standard of care. Romiplostim did not appear to be associated with an increased risk of haematological malignancies or an increased risk of thrombotic events. Although binding antibodies against romiplostim or thrombopoietin developed in some romiplostim recipients, with neutralizing antibodies to romiplostim detected in two romiplostim recipients, antibodies cross reacting to thrombopoietin have not been detected. Romiplostim was associated with modest increases in bone marrow reticulin in some patients with ITP; reductions in reticulin were usually seen when romiplostim was discontinued. In conclusion, subcutaneous romiplostim is a valuable agent for use in patients with refractory chronic ITP.

Pilot study of the effect of romiplostim on child health-related quality of life (HRQoL) and parental burden in immune thrombocytopenia (ITP)

BACKGROUND

Childhood ITP can have a negative impact on the child and his/her family even though it is typically a benign disorder with low risk of serious bleeding. In adults and now children, romiplostim increases the platelet count without significant adverse effects. In this study, the impact of romiplostim treatment on the HRQoL of children with chronic ITP was assessed using the Kid's ITP Tools (KIT).

PROCEDURE

Subjects 1-18 years old, with chronic ITP (>6 months), were enrolled in a multi-center, randomized, double-blind, placebo-controlled phase 1/2 treatment study with romiplostim (reported elsewhere). Subjects and/or proxies completed the KIT at baseline, week 5, and week 13. Scores were computed for child self-report (children >7 years), proxy-report, and parent impact. Changes in mean scores from baseline to week 13 were computed.

RESULTS

Twenty-two children (17 receiving romiplostim, 5 placebo) and/or their parents provided data. Change in mean scores demonstrated significant improvement in HRQoL for romiplostim versus placebo for parent impact (24 ± 17 vs. -6 ± 8; P = 0.008). Change scores for child self-report trended toward improvement with romiplostim and decreased with placebo (5 ± 10 vs. -7 ± 17; P = 0.29). Romiplostim proxy-report mean change scores were 6 points higher than placebo (8 ± 16 vs. 2 ± 12; P = 0.50).

CONCLUSIONS

Romiplostim significantly reduced parental burden in this study. Whether the same and/or additional improvements in HRQoL would be demonstrated by a larger, longer study of romiplostim-treated children with ITP remains to be determined. Pediatr Blood Cancer 2012; 58: 395-398. © 2011 Wiley Periodicals, Inc.

Use of romiplostim for primary immune thrombocytopenia in children

Very little has been published on the use of romiplostim to treat primary immune thrombocytopenia (ITP), refractory to previous treatments, in children. The objective of this study was to determine its efficacy and safety in pediatric patients in a university general hospital. Retrospective, longitudinal observational study of pediatric patients on treatment with romiplostim. The principal efficacy variable was platelet count. Safety was evaluated by recording possible adverse reactions to the medication, monitoring the appearance of thrombosis, thrombocytopenia during dose reduction, hemorrhage, and myelodysplastic syndromes. Three patients in the authors' center have been treated with romiplostim (subcutaneous [SC], initial dose: 1 μg/kg/week) for ITP refractory to various treatments: 1 with newly diagnosed ITP and 2 with chronic ITP. Patients were followed up for 27 to 39 weeks after starting treatment. Responses were achieved in 7 to 28 days, and complete responses were maintained for 37% to 91% of the follow-up period, with median platelet counts between 40 × 10(3)/μL and 215 × 10(3)/μL. The adverse reactions observed during follow-up were headache and asthenia in one patient and mucocutaneous bleeding after dose suspension in another one. With regard to effectiveness, the response in the 3 patients was varied. The drug was considered to be safe, as there were only mild adverse reactions. Although further studies and long-term follow-up are required, these results show that romiplostim could be considered an alternative to immunosuppressive therapies, such as rituximab, or splenectomy in refractory chronic ITP.

Clinical and research issues in neonatal anemia and thrombocytopenia

PURPOSE OF REVIEW

Anemia and thrombocytopenia are the most common hematological problems in neonates. Red blood cell (RBC) and platelet transfusions are the mainstays of therapy, but data to guide neonatal transfusion practices have been sparse. Recombinant hematopoietic growth factors represent another therapeutic alternative, but their use in this population requires a solid understanding of the developmental differences between fetal and adult hematopoiesis.

RECENT FINDINGS

Recently, follow-up studies from children randomized as neonates to either liberal or restrictive RBC transfusion approaches were published. Results of these studies have so far been contradictory and have generated more questions than answers. New developmental stage-specific problems associated with RBC transfusions were also uncovered, such as the transfusion-associated necrotizing enterocolitis. Finally, two thrombopoietin (Tpo) mimetics were approved by the FDA for the treatment of adults with chronic immune thrombocytopenia, thus offering a novel potential therapeutic alternative for thrombocytopenic neonates.

SUMMARY

In this review, we will discuss the currently available data regarding neonatal RBC and platelet transfusion thresholds, as well as the potential limitations, and concerns associated with the use of erythropoietin and Tpo mimetics in this patient population. Finally, we will point out specific areas wherein additional research is critically needed.

Diagnosis and Management of Immune Thrombocytopenia in the Era of Thrombopoietin Mimetics

The recognition of that patients with Immune Thrombocytopenia (ITP) have functional thrombopoietin deficiency and decreased platelet production due to immune-mediated megakaryocytic injury has challenged the traditional view of this disease as predominantly a disorder of antibody-mediated platelet destruction. The therapy of chronic refractory ITP has been transformed by the approval of the thrombopoietin minetics, romiplostim and eltrombopag, which have shown remarkable efficacy in randomized trials. The use of these agents earlier in the disease course after failure of corticosteroid therapy remains controversial. In this article, we review the current data on the efficacy and safety of thrombopoietin receptor agonists and discuss other therapies as well as diagnostic work up of ITP.

Romiplostim: Idiopathic Thrombocytopenic Purpura (Children/Adolescents)

This Hospital Pharmacy feature is extracted from Off-Label Drug Facts, a quarterly publication available from Wolters Kluwer Health. Off-Label Drug Facts is a practitioner-oriented resource for information about specific drug uses that are unapproved by the US Food and Drug Administration. This new guide to the literature enables the health care professional or clinician to quickly identify published studies on off-label uses and determine if a specific use is rational in a patient care scenario. References direct the reader to the full literature for more comprehensive information before patient care decisions are made. Direct questions or comments regarding Off-Label Drug Uses to jgeneral@kumc.edu .