Open Label Extension Study of AMG 531 in Japanese Subjects With ITP

Phase 2

Completed

Conditions: Immune (Idiopathic) Thrombocytopenic Purpura (ITP)

Interventions: Biological: AMG 531

Registration Number: NCT00440037

Lead Sponsor: Kyowa Kirin Co., Ltd.

Brief Summary: The purpose of this study is to assess the safety and efficacy of long term dosing of AMG 531 in thrombocytopenic Japanese subjects with ITP.

It is anticipated that AMG 531 will be a safe and well tolerated in long term treatment and that AMG 531 will effectively raise and maintain platelet counts to a desired therapeutic range, when individual dose adjustments based on platelet counts are permitted.

This study is available to subjects who have completed any previous AMG 531 ITP study in Japan and meet the eligibility criteria of this study.

Detailed Description: Romiplostim was administered by subcutaneous (SC) injection once per week. If subjects entered the extension study within 12 weeks from the last investigational product administration in the previous study and had shown an increase in platelet counts ≥ 20 x 109/L from baseline at least once during the 13-week treatment period (excluding 4 weeks after receiving rescue medication), they were treated with romiplostim at the same weekly dose (last dose on study) received in the previous study. Otherwise, subjects were treated with romiplostim at a starting dose of 3 μg/kg. Dose adjustment based on platelet counts was allowed throughout the treatment period to allow subjects to maintain platelet counts in the target range of ≥ 50 to ≤ 200 x 109/L, up to a maximum permitted dose of 10 μg/kg.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 44

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
AMG 531	AMG 531	-

Primary Outcome Measures

Name	Time	Method
Percentage of Participants With Adverse Events Including Clinically Significant Changes in Laboratory Values.	Through study completion, the median treatment duration (time between first dose and last dose) was 146.0 weeks (range: 12 to 243 weeks)	Subjects who reported at least 1 adverse event after beginning treatment with romiplostim in this study

Secondary Outcome Measures

Name	Time	Method
Incidence of Anti AMG 531 Antibody Formation	Through study completion, the median treatment duration (time between first dose and last dose) was 146.0 weeks (range: 12 to 243 weeks)	Subjects with positive anti-AMG 531 antibodies (either to the peptide portion of AMG 531 or to the intact molecule) and antibodies that cross-react with endogenous thrombopoietin (TPO)
Change From Baseline in Patient-reported Outcome (PRO) Endpoints at Each Time Point (Baseline PRO is Obtained at Day 1 Predose)	By Week 48	Short Form 36 (SF-36): The SF-36 has 36 questions with 8 domains: Physical Functioning, Role Physical, Bodily Pain, General Health, Vitality, Social Functioning, Role Emotional, and Mental Health. In addition to deriving a score for each of the domains, the SF-36 generates 2 summary scores: a physical component summary (PCS) and a mental component summary (MCS). These 8 domains and 2 summary scores are scored from 0 to 100, with higher scores indicating better health status. The official version in Japanese was used in this study. Euroqol-5 Dimensions (EQ-5D): The EQ-5D is a patient-completed, multidimensional measure of HRQOL. EQ-5D index values range from -0.59 to 1.00. The EQ-5D visual analogue scale (VAS) records the respondents' self-rated health status on a vertical graduated (0 to 100) visual analogue scale. Higher EQ-5D Index and VAS scores represent better health status. The official version in Japanese was used in this study.
Incidence of Platelet Response (Platelet Response is Defined as a Doubling of Baseline Platelet Counts and More Than 50 x 10^9/L; Baseline Platelet Counts is That Obtained in the Previous Study)	Through study completion, the median treatment duration (time between first dose and last dose) was 146.0 weeks (range: 12 to 243 weeks)
Percentage of Subjects Able to Reduce or Discontinue Their Concurrent ITP Therapies (for Subjects That Are Receiving Oral Corticosteroids at a Constant Dose and Schedule at the Screening Visit)	Through study completion, the median treatment duration (time between first dose and last dose) was 146.0 weeks (range: 12 to 243 weeks)