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A summary of the Romiplostim or Standard of Care in Patients with Immune Thrombocytopenia article previously published.3
Immune thrombocytopenia (ITP) is an autoimmune disease characterized by low platelet counts due to both increased platelet destruction and suboptimal platelet production.1 Many therapies are aimed at reducing platelet destruction.2 Treatments aimed at increasing platelet production, alone or in combination with existing therapies, provide an opportunity to improve outcomes in patients with ITP.2 The thrombopoietin mimetic Nplate® (romiplostim) is an Fc-peptide fusion protein that stimulates platelet production by binding the thrombopoietin receptor, thereby increasing the body’s natural production of platelets.3 Nplate® is a thrombopoietin receptor agonist indicated for the treatment of thrombocytopenia in patients with chronic ITP who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. Nplate® is not indicated for the treatment of thrombocytopenia due to myelodysplastic syndrome (MDS) or any cause of thrombocytopenia other than chronic ITP. Nplate® should be used only in patients with ITP whose degree of thrombocytopenia and clinical condition increase their risk for bleeding. Nplate® should not be used in an attempt to normalize platelet counts.
A summary of the trial that compares Nplate® to medical standard of care (SOC) in patients with ITP published in the New England Journal of Medicine is presented. The design of the trial does not allow for the comparison of Nplate® to the individual treatments received in the SOC arm.
Thrombopoietin Mimetics Thrombopoietin mimetics increase platelet count in patients with chronic ITP and reduce the risk of bleeding.2,4 Nplate®, a thrombopoietin mimetic, increases platelet production by binding to and activating the thrombopoietin receptor, a mechanism analogous to endogenous thrombopoietin.5 In patients who have had an insufficient response to corticosteroids or immunoglobulins, Nplate® may offer the potential for effective maintenance treatment in patients who wish to avoid or defer splenectomy or in whom splenectomy is contraindicated.5,7 Continuous weekly treatment with Nplate® increases platelet counts in many patients who have chronic ITP with an acceptable safety profile.4
Important Safety Information
Two 6-month, Phase 3 Pivotal Trials2,5The results from the SOC study should be viewed in context with the prior pivotal, prospective, multicenter, randomized, placebo-controlled, international, double-blind phase 3 studies that evaluated Nplate® and placebo, one in splenectomized and one in nonsplenectomized patients. The primary end point was durable platelet response (weekly platelet responses of ≥ 50 × 109/L during 6 or more weeks of the last 8 weeks of treatment; no rescue therapy at any time during study). The secondary end point was overall platelet response (durable plus transient* rates of platelet response).
In nonsplenectomized patients:
In splenectomized patients:
In the pivotal trials for Nplate®, prior ITP treatments in the Nplate® and control groups included corticosteroids, immunoglobulins, rituximab, cytotoxic therapies, danazol, and azathioprine. Patients receiving corticosteroids, azathioprine or danazol at a constant dosing schedule were allowed to continue receiving these medical treatments throughout the studies.
The recommended starting dose for Nplate® is 1 µg/kg. See the Nplate® prescribing information for complete dosing instructions, including guidelines for dose adjustments. In the pivotal trials, the median dose of Nplate® was 2 µg/kg (25th–75th percentile: 1–3 µg/kg) in the study of nonsplenectomized patients and 3 µg/kg (25th–75th percentile: 2–7 µg/kg) in the study of splenectomized patients.
Study Design3
*Four or more weekly platelet responses without a durable platelet response from week 2 to 25.
Patient Population3
1-Year Randomized, Controlled, Open-Label Trial to Evaluate Nplate® or Medical SOC in Nonsplenectomized Adult Patients Diagnosed with ITP3
Primary and Secondary End Points3
Study Results3: Platelet Count Over 1 YearThe mean platelet count was higher in the romiplostim group than in the SOC group throughout the treatment period.
Patients in the Nplate® Group Were 2.3 Times as Likely to Have a Platelet Response as Those in the SOC Group (95% confidence interval, 2.0-2.6; P < 0.001)
Treatment Failure and SplenectomyThe incidence of treatment failure was significantly lower among patients receiving romiplostim (18/157 [11%]) than among those receiving SOC (23/77 [30%], P < 0.001).
The time to treatment failure was significantly longer in the Nplate® group than in the SOC group (P = 0.02).
Incidence of splenectomy was significantly lower among patients receiving romiplostim (14/157 [9%]) than among those receiving SOC (28/77 [36%], P < 0.001). Time to splenectomy was also significantly longer in the romiplostim group than in the SOC group (P < 0.001).
Throughout the study, all patients could receive additional therapies for ITP (including short-term rescue therapies, such as intravenous immune globulin, but excluding other thrombopoietin mimetics and investigational products) if they were deemed medically necessary by the investigator.
Safety3
IndicationNplate® is a thrombopoietin receptor agonist indicated for the treatment of thrombocytopenia in patients with chronic immune thrombocytopenia (ITP) who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy.
Nplate® is not indicated for the treatment of thrombocytopenia due to myelodysplastic syndrome (MDS) or any cause of thrombocytopenia other than chronic ITP. Nplate® should be used only in patients with ITP whose degree of thrombocytopenia and clinical condition increase the risk for bleeding. Nplate® should not be used in an attempt to normalize platelet counts.
Nplate® (romiplostim)Important Safety Information
Risk of Progression of Myelodysplastic Syndromes to Acute Myelogenous Leukemia
Thrombotic/Thromboembolic Complications
Bone Marrow Reticulin Formation and Risk for Bone Marrow Fibrosis
Worsened Thrombocytopenia after Cessation of Nplate®
Lack or Loss of Response to Nplate®
Laboratory Monitoring
Adverse Reactions
References:
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