Evaluation of bleeding and thrombotic events during long-term use of romiplostim in patients with chronic immune thrombocytopenia (ITP)

Splenectomy as a curative treatment for immune thrombocytopenia: a retrospective analysis of 233 patients with a minimum follow up of 10 years

The treatment of choice in steroid-resistant immune thrombocytopenia is still controversial due to the recent advent of new drugs (anti-CD20 antibodies and thrombopoietin mimetics) that have encouraged a generalized tendency to delay splenectomy. Consequently, it is extremely importance to define the efficacy and safety of splenectomy in the long term. We retrospectively analyzed the data of 233 patients affected by immune thrombocytopenia who underwent splenectomy between 1959 and 2001 in 6 European hematologic institutions and who have now a minimum follow up of ten years from surgery. Of the 233 patients, 180 (77%) achieved a complete response and 26 (11%) a response. Sixty-eight of 206 (33%) responsive patients relapsed, mostly (75%) within four years from first response. In 92 patients (39.5%), further treatment was required after splenectomy that was effective in 76 cases (83%). In 138 patients (59%), response was maintained free of any treatment at last contact. No significant association between baseline characteristics and likelihood of stable response was found. Overall, 73 (31%) and 58 (25%) patients experienced at least one infectious or hemorrhagic complication, which was fatal in 2 and 3 patients, respectively. A stable response to splenectomy was associated with a lower rate of infections (P=0.004) and hemorrhages (P<0.0001). Thrombosis developed in 18 patients (8%) and was fatal in 4. Splenectomy achieved a long-term stable response in approximately 60% of cases. Complications mainly affected non-responding patients and were fatal in a minority.

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.

Contemporary management of primary immune thrombocytopenia in adults

Immune thrombocytopenia (ITP) comprises a syndrome of diverse disorders that have in common immune-mediated thrombocytopenia, but that differ with respect to pathogenesis, natural history and response to therapy. ITP may occur in the absence of an evident predisposing etiology (primary ITP) or as a sequela of a growing list of associated conditions (secondary ITP). Primary ITP remains a diagnosis of exclusion and must be differentiated from non-autoimmune etiologies of thrombocytopenia and secondary causes of ITP. The traditional objective of management is to provide a hemostatic platelet count (> 20-30 × 10(9) L(-1) in most cases) while minimizing treatment-related toxicity, although treatment goals should be tailored to the individual patient and clinical setting. Corticosteroids, supplemented with either intravenous immune globulin G or anti-Rh(D) as needed, are used as upfront therapy to stop bleeding and raise the platelet count acutely in patients with newly diagnosed or newly relapsed disease. Although most adults with primary ITP respond to first-line therapy, the majority relapse after treatment is tapered and require a second-line approach to maintain a hemostatic platelet count. Standard second-line options include splenectomy, rituximab and the thrombopoietin receptor agonists, romiplostim and eltrombopag. Studies that directly compare the efficacy, safety and cost-effectiveness of these approaches are lacking. In the absence of such data, we do not favor a single second-line approach for all patients. Rather, we consider the pros and cons of each option with our patients and engage them in the decision-making process.

Patients with ≥ 20 × 10(9)/l platelets at baseline may have a prompt response to romiplostim during the early phase of treatment: an italian single-institution experience

Patients with chronic immune thrombocytopenia treated with romiplostim may benefit from a higher starting dose when a rapid increase in count is needed, but it could be avoided in those with a prompt response to the standard dosage. We hypothesized that a platelet count ≥ 20 × 10⁹/l at baseline could distinguish subjects with such response from those with a delayed one during the early phase of treatment. Our work is a retrospective and single-institution analysis comparing the median platelet count, the median weekly dosage of romiplostim and the median number of weekly platelet counts < 50 × 10⁹/l between patients with a baseline ≥ 20 × 10⁹/l platelets (n=10, 2 splenectomized) and those with a lower one (n=8, 3 splenectomized) during the first month of treatment with romiplostim. The results show a higher median platelet count (79,5 vs 40,5 × 10⁹/l, p=0,002) and a lower median dose of romiplostim (1 vs 2 mcg/kg/week, p=0,01) in subjects with a baseline ≥ 20 × 10⁹/l platelets, who also had a trend of less weekly counts < 50 × 10⁹/l platelets (1 vs 2, p=0,054). These data suggest that patients with ≥ 20 × 10⁹/l platelets at baseline may achieve a prompt response with the standard dose of romiplostim, but further and larger data are needed in order to assess whether it can be considered in clinical practice.

Romiplostim as Early Treatment of Immune Thrombocytopenia with Severe Immunodeficiency

Immunosuppressive agents are the standard therapeutic approach for immune thrombocy-topenia (ITP). Their prolonged use may increase the risk of infectious complications, particularly when the patient is already at higher infectious risk. In this setting, the use of drugs with a mechanism of action alternative to immunosuppression, like thrombopoietin receptor agonists (TRAs), may find particular indication. We report the unique case of a patient with severe immunodeficiency and ITP, who experienced a serious infectious complication while on steroids treatment, and who was successfully treated with Romiplostim second-line. The present experience supports the effectiveness and safety of TRAs as early treatment of ITP patients with drug-induced immunodeficiency or with active infections.

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.

A novel approach to the evaluation of bleeding-related episodes in patients with chronic immune thrombocytopenia

OBJECTIVE

In clinical studies of patients with severe thrombocytopenia, rescue treatments are used to prevent or stop bleeding. Estimating risk reductions of bleeding for clinical study medications can be challenging. This study evaluated a new and possibly more accurate way of assessing the effects of a treatment intervention on bleeding-related outcomes. We developed a composite endpoint, termed bleeding-related episodes (BRE).

RESEARCH DESIGN AND METHODS

BREs were assessed in a post-hoc analysis of patients with chronic immune thrombocytopenia (ITP) who participated in two romiplostim, phase 3, placebo-controlled studies. Patients received romiplostim or placebo once weekly for 24 weeks. A BRE was defined as an actual bleeding event and/or the use of rescue medication. In total, 125 patients (41 placebo, 84 romiplostim) with platelet counts <30 K were enrolled.

CLINICAL TRIAL REGISTRATION

NCT00102323/NCT00102336.

RESULTS

The rate of all BREs across all studies was reduced by 56% in patients receiving romiplostim compared with placebo. The rate of BREs using immunoglobulin (IVIg or anti-D Ig) was reduced by 89% in patients receiving romiplostim compared with placebo. BREs were more frequent in both groups at platelet counts <50 × 10(9)/L. Results were similar between splenectomized and nonsplenectomized patients. We believe that prior to the development of this tool, bleeding events were underdiagnosed. The BRE tool allowed the identification of multiple interventions within bleeding episodes, which may have required separate interventions and were therefore considered to be additional BREs.

CONCLUSIONS

In this study, the composite endpoint of a bleeding event and the use of rescue medication within close proximity of the bleeding event appears to be feasible and informative. The BRE tool allows for more precise understanding of the effect of rescue therapies in ITP and has broader applications to future clinical trials where assessment of bleeding risk can be complicated or masked by rescue interventions.

LIMITATIONS

This was a post hoc analysis. The assignment of platelet counts to a BRE was based on the platelet count on the first day of a BRE, which may not reflect the platelet count during the entire episode, and the assignment of platelet counts was based on the estimation required for events that occurred between weekly measurements.

Immune thrombocytopenia: no longer 'idiopathic'

Immune thrombocytopenia (ITP) is a common hematologic disorder. Its pathogenesis involves both accelerated platelet destruction and impaired platelet production. First-line agents are usually effective initially but do not provide long-term responses. Splenectomy remains an effective long-term therapy, as does rituximab (Rituxan) in a subset of patients. Thrombopoietic agents offer a new alternative, although their place in the overall management of ITP remains uncertain.

Management of immune thrombocytopenic purpura in children: potential role of novel agents

The treatment of immune thrombocytopenic purpura (ITP) in children is controversial, requiring individualized assessment of the patient and consideration of treatment options. If the platelet count is >10 000/μL and the patient is asymptomatic, a 'watch and wait' strategy is appropriate since most children with ITP will recover completely without pharmacotherapy. If therapy is indicated because of bleeding or a platelet count <10 000/μL, then treatment with glucocorticoids, intravenous immunoglobulin (IVIg), or anti-D are possible initial choices. Glucocorticoid treatment is the least expensive and is our usual first choice of therapy. Its use assumes that the blood counts and blood film have been evaluated to ensure the absence of evidence of alternative diagnoses, such as thrombotic thrombocytopenic purpura or incipient acute leukemia. IVIg is expensive and often causes severe headache, nausea and vomiting, and requires hospitalization at our institution. Anti-D therapy is also expensive and can only be used in patients who are Rhesus D positive. These therapies, even if only transiently effective, can be repeated if necessary. Children usually recover from newly diagnosed ITP, with or without multiple courses of medical therapy. If the disease becomes 'persistent' with severe thrombocytopenia and/or bleeding, and is no longer responsive to the three first-line therapies, the next approach includes the use of thrombopoietin receptor agonists or rituximab. When the disease persists for more than 1 year, it is considered chronic, and, if symptomatic, it may become necessary to consider third-line therapies, including splenectomy, alternative immunosuppressive agents, or combination or investigative chemoimmunotherapy. This review considers the indications, mechanism of action, and effectiveness of the traditional and novel treatment options for patients with ITP.

The American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia

Immune thrombocytopenia (ITP) is commonly encountered in clinical practice. In 1996 the American Society of Hematology published a landmark guidance paper designed to assist clinicians in the management of this disorder. Since 1996 there have been numerous advances in the management of both adult and pediatric ITP. These changes mandated an update in the guidelines. This guideline uses a rigorous, evidence-based approach to the location, interpretation, and presentation of the available evidence. We have endeavored to identify, abstract, and present all available methodologically rigorous data informing the treatment of ITP. We provide evidence-based treatment recommendations using the GRADE system in those areas in which such evidence exists. We do not provide evidence in those areas in which evidence is lacking, or is of lower quality--interested readers are referred to a number of recent, consensus-based recommendations for expert opinion in these clinical areas. Our review identified the need for additional studies in many key areas of the therapy of ITP such as comparative studies of "front-line" therapy for ITP, the management of serious bleeding in patients with ITP, and studies that will provide guidance about which therapy should be used as salvage therapy for patients after failure of a first-line intervention.

Romiplostim in children with chronic refractory ITP: randomized placebo controlled study

Romiplostim stimulates thrombopoietin receptor to increase platelet production of megakaryocytes in idiopathic thrombocytopenic purpura (ITP). This study aimed to evaluate the safety and efficacy of romiplostim in children with chronic ITP. Eighteen patients with chronic ITP, either none responsive or failed to maintain response on two or more therapeutic modalities, were enrolled. Patients were randomized (2:1) to receive romiplostim or placebo for 12 weeks, initiated at 1 μg/kg/week, escalated to 5 μg/kg/week, and then tapered. Median patients' age was 8.5 years, and the median baseline platelet count (PC) was 10.5 × 10(9)/L. The median weekly dose of romiplostim was 2 μg/kg. Fifty percent of patients in both romiplostim and placebo arms had at least one adverse event (AE); none was serious. Ten patients on romiplostim (83.3%) maintained the efficacy endpoint (PC > 50,000). Romiplostim was well-tolerated and efficient in treating the children with chronic refractory ITP with no unexpected AEs.

Eltrombopag for management of chronic immune thrombocytopenia (RAISE): a 6-month, randomised, phase 3 study

BACKGROUND

Eltrombopag is an oral thrombopoietin receptor agonist for the treatment of thrombocytopenia. We aimed to compare the response to once daily eltrombopag versus placebo in patients with chronic immune thrombocytopenia during a 6-month period.

METHODS

We undertook a phase 3, double-blind, placebo-controlled study in adults with previously treated immune thrombocytopenia of more than 6 months' duration who had baseline platelet counts lower than 30,000 per μL. Patients were randomly allocated (in a 2:1 ratio) treatment with local standard of care plus 50 mg eltrombopag or matching placebo once daily for 6 months. Randomisation was done centrally with a computer-generated randomisation schedule and was stratified by baseline platelet count (≤ 15,000 per μL), use of treatment for immune thrombocytopenia, and splenectomy status. Patients, investigators, and those assessing data were masked to allocation. Dose modifications were made on the basis of platelet response. Patients were assessed for response to treatment (defined as a platelet count of 50,000-400,000 per μL) weekly during the first 6 weeks and at least once every 4 weeks thereafter; the primary endpoint was the odds of response to eltrombopag versus placebo. Analysis was by intention to treat. This study is registered at ClinicalTrials.gov, number NCT00370331.

FINDINGS

Between Nov 22, 2006, and July 31, 2007, 197 patients were randomly allocated to treatment groups and were included in the intention-to-treat analysis (135 eltrombopag, 62 placebo). 106 (79%) patients in the eltrombopag group responded to treatment at least once during the study, compared with 17 (28%) patients in the placebo group. The odds of responding were greater in patients in the eltrombopag group compared with those in the placebo group throughout the 6-month treatment period (odds ratio 8·2, 99% CI 3·59-18·73; p<0·0001). 37 (59%) patients receiving eltrombopag reduced concomitant treatment versus ten (32%) patients receiving placebo (p=0·016). 24 (18%) patients receiving eltrombopag needed rescue treatment compared with 25 (40%) patients receiving placebo (p=0·001). Three (2%) patients receiving eltrombopag had thromboembolic events compared with none in patients on placebo. Nine (7%) eltrombopag-treated patients and two (3%) in the placebo group had mild increases in alanine aminotransferase concentration, and five (4%) eltrombopag-treated patients (vs none allocated to placebo) had increases in total bilirubin. Four (7%) patients taking placebo had serious bleeding events, compared with one (<1%) patient treated with eltrombopag.

INTERPRETATION

Eltrombopag is effective for management of chronic immune thrombocytopenia, and could be particularly beneficial for patients who have not responded to splenectomy or previous treatment. These benefits should be balanced with the potential risks associated with eltrombopag treatment.

FUNDING

GlaxoSmithKline.

Analysis of EQ-5D scores from two phase 3 clinical trials of romiplostim in the treatment of immune thrombocytopenia (ITP)

OBJECTIVE

Utility-based measures of quality of life are recommended by some decision makers in health care. No studies have addressed changes in utility in patients with chronic idiopathic thrombocytopenia (ITP). This study sought to assess the health utilities of patients with chronic ITP and to evaluate the association of change in health utility with changes in other variables, including platelet response status and bleeding events.

METHODS

We analyzed EQ-5D data from two international, randomized, placebo-controlled, double-blind, 24-week trials that evaluated the efficacy and safety of romiplostim in adult patients with chronic ITP.

RESULTS

A total of 125 subjects participated. Mean change, adjusted for age, gender, splenectomy status, and baseline score using multiple linear regression models was greater for romiplostim versus placebo for the EQ-5D index score (0.05 vs. -0.03, P = 0.015) and the VAS score (6.42 vs. 0.48, P = 0.066); similar for durable platelet responders versus nonresponders; and greater for EQ-5D index scores for subjects who did not have a bleeding event during the study (n = 29) compared to subjects who did have a bleeding event (n = 47) (0.06 vs. 0.005; P = 0.066).

CONCLUSIONS

Using romiplostim in cases of chronic ITP was associated with improvement in health-related quality of life as measured by the EQ-5D index score. Health utility scores derived using the EQ-5D in this study may be useful for determining quality-adjusted life years (QALYs) in economic evaluations of romiplostim for treatment of chronic ITP.

Romiplostim or standard of care in patients with immune thrombocytopenia

BACKGROUND

Romiplostim, a thrombopoietin mimetic, increases platelet counts in patients with immune thrombocytopenia, with few adverse effects.

METHODS

In this open-label, 52-week study, we randomly assigned 234 adult patients with immune thrombocytopenia, who had not undergone splenectomy, to receive the standard of care (77 patients) or weekly subcutaneous injections of romiplostim (157 patients). Primary end points were incidences of treatment failure and splenectomy. Secondary end points included the rate of a platelet response (a platelet count >50×10(9) per liter at any scheduled visit), safety outcomes, and the quality of life.

RESULTS

The rate of a platelet response in the romiplostim group was 2.3 times that in the standard-of-care group (95% confidence interval [CI], 2.0 to 2.6; P<0.001). Patients receiving romiplostim had a significantly lower incidence of treatment failure (18 of 157 patients [11%]) than those receiving the standard of care (23 of 77 patients [30%], P<0.001) (odds ratio with romiplostim, 0.31; 95% CI, 0.15 to 0.61). Splenectomy also was performed less frequently in patients receiving romiplostim (14 of 157 patients [9%]) than in those receiving the standard of care (28 of 77 patients [36%], P<0.001) (odds ratio, 0.17; 95% CI, 0.08 to 0.35). The romiplostim group had a lower rate of bleeding events, fewer blood transfusions, and greater improvements in the quality of life than the standard-of-care group. Serious adverse events occurred in 23% of patients (35 of 154) receiving romiplostim and 37% of patients (28 of 75) receiving the standard of care.

CONCLUSIONS

Patients treated with romiplostim had a higher rate of a platelet response, lower incidence of treatment failure and splenectomy, less bleeding and fewer blood transfusions, and a higher quality of life than patients treated with the standard of care. ( ClinicalTrials.gov number, NCT00415532.).