Interventional Study in Adults With Immune Thrombocytopenia Purpura (ITP) Receiving Romiplostim

Phase 2

Completed

Conditions: Idiopathic Thrombocytopenic Purpura

Interventions: Biological: Romiplostim

Registration Number: NCT01143038

Lead Sponsor: Amgen

Brief Summary: The purpose of this study is to describe the number of months with a platelet response over a 12 month treatment period and to describe ITP remission rates in adults with ITP receiving romiplostim.

Detailed Description: The study includes a 4-week screening period, a 12-month romiplostim treatment period, and a romiplostim dose-tapering period.

During the 12-month treatment period romiplostim doses could be increased or decreased to maintain a platelet count between ≥ 50 x 10\^9/L and ≤ 200 x 10\^9/L. Participants who dose reduce such that they no longer require treatment with romiplostim during the 12-month treatment period will continue with all required study procedures up to 12 months and will be monitored for ITP remission for at least 6 months.

At the completion of the 12-month treatment period, participants receiving only romiplostim and with a platelet count ≥ 50 x 10\^9/L will enter the tapering period, during which the romiplostim dose will be decreased by 1 µg/kg every 2 weeks, for up to 19 weeks. If a participant maintains a platelet count of ≥ 50 x 10\^9/L in the absence of romiplostim and all medications for ITP (concomitant or rescue), the participant will be followed for at least 6 months to confirm the incidence of ITP remission. If a participant's platelet count falls below 50 x 10\^9/L and the participant has tapered off treatment with romiplostim, the participant will enter the stabilization period and reinitiate romiplostim for up to 8 weeks.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 75

Inclusion Criteria

Subject has been diagnosed with primary ITP according to the American Society of Hematology (ASH) guidelines (George et al, 1996) and previously received only 1st line therapies.

First line therapy is defined as corticosteroids, immunoglobulin G (IVIG), anti-D and vinca alkaloids (used for the treatment of ITP related thrombocytopenia only). A platelet transfusion at any time during the six month period since the original diagnosis would not exclude the subject from study participation

Initial diagnosis of primary ITP within 6 months of enrollment
Age ≥ 18 years at screening
A single platelet count ≤ 30 x 10⁹/L at any time during the screening period
Subject or subject's legally acceptable representative has provided informed consent

Exclusion Criteria

Known history of a bone marrow stem cell disorder
Surgical resection of the spleen
Subject has a history of cancer or current malignancy other than basal cell carcinoma or cervical cancer in-situ with active treatment or disease within 5 years of screening
Known history of congenital thrombocytopenia
Known history of hepatitis B, hepatitis C, or human immunodeficiency virus
Positive H. pylori by urea breath test or stool antigen test at screening
Known history of systemic lupus erythematosus, Evans syndrome, or autoimmune neutropenia
Known history of antiphospholipid antibody syndrome or positive for lupus anticoagulant
Known history of disseminated intravascular coagulation, hemolytic uremic syndrome, or thrombotic thrombocytopenic purpura
Previous history of recurrent venous thromboembolism or thrombotic events or an occurrence within 5 years of enrollment.
Previous use of romiplostim, pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF), eltrombopag, recombinant human thrombopoietin (rHuTPO) or any platelet producing agent
Rituximab (for any indication) or mercaptopurine (6-MP) or anticipated use during the time of the proposed study
All hematopoietic growth factors including interleukin-11 (IL-11) (oprelvekin) within 4 weeks before the screening visit
Alkylating agents use at any time before or during the screening visit or anticipated during the time of the proposed study
Known hypersensitivity to any recombinant E. coli-derived product (eg, Infergen, Neupogen, Somatropin, and Actimmune)
Currently enrolled in another investigational device or drug study, or less than 30 days since ending another investigational device or drug study(s), or receiving other investigational agent(s)
Subject will have any other investigational procedures performed while enrolled in this clinical study
Subject is pregnant or breast feeding, or planning to become pregnant within 5 weeks after the end of treatment
Female subject of child bearing potential is not willing to use, in combination with her partner, highly effective contraception during treatment and for 4 weeks after the end of treatment
Subject has previously enrolled into a romiplostim study
Subject will not be available for protocol required study visits, to the best of the subject's and investigator's knowledge
Subject has any kind of disorder that, in the opinion of the investigator, may compromise the ability of the subject to give written informed consent and/or to comply with all required study procedures

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Romiplostim	Romiplostim	Participants received romiplostim administered weekly by subcutaneous injection during the 12-month treatment period. The starting dose was 1 μg/kg with weekly dose increases continued in increments of 1 μg/kg/week to a maximum dose of 10 μg/kg in an attempt to reach a target platelet count of ≥ 50 x 10\^9/L.

Primary Outcome Measures

Name	Time	Method
Number of Months With Platelet Response During the 12-Month Treatment Period	12 months	The primary endpoint was the number of months a participant achieved a platelet response during the 12-month treatment period. A platelet response for any 1 month was defined as the median of platelet counts measured in the month ≥ 50 x 10\^9/L. Platelet counts within 4 weeks following a rescue medication use or following splenectomy were considered non-response. Months without any platelet count measurement were considered as months with no platelet response.

Secondary Outcome Measures

Name	Time	Method
Percentage of Participants With Splenectomy During the 12-month Treatment Period	12 months	If treatment with romiplostim was deemed ineffective or intolerable by the investigator, a splenectomy may have been performed.
Number of Participants Who Developed Antibodies to Romiplostim	Baseline and at end of treatment (based on response to treatment, this could occur between 12 months and approximately 18 months)	The number of participants who developed antibody formation (defined as negative at baseline and positive at post-baseline, transient or persistent) to romiplostim, endogenous thrombopoietin (eTPO), and thrombopoietin mimetic peptide (TMP, the peptide component of romiplostim) was summarized.
Percentage of Participants With ITP Remission	Up to 24 months	ITP remission was defined as maintaining every platelet count ≥ 50 x 10\^9/L for at least 6 months in the absence of romiplostim and any other therapies to treat ITP.
Number of Participants With Adverse Events	From first dose date of romiplostim to end of study (up to 24 months).	An adverse event (AE) is defined as any untoward medical occurrence in a clinical trial participant. The event does not necessarily have a causal relationship with study treatment. A serious adverse event is defined as an adverse event that meets at least one of the following serious criteria: • fatal • life threatening • requires in-patient hospitalization or prolongation of existing hospitalization • results in persistent or significant disability/incapacity • congenital anomaly/birth defect • other significant medical hazard. Whether an adverse event was treatment-related (TRAE) or not was determined by investigator.