REDUCED HOSPITALIZATIONS AND BLEEDS IN ADULTS WITH PRIMARY IMMUNE THROMBOCYTOPENIA (ITP) RECEIVING ROMIPLOSTIM IN CLINICAL PRACTICE – INTERIM RESULTS FROM A LARGE, EUROPEAN, OBSERVATIONAL STUDY

Background:

ITP is characterized by platelet counts <100x109/L, with romiplostim recommended for second-line treatment of adult ITP. Patients (pts) with more severe disease may experience bleeding symptoms which require hospitalization. Such hospitalizations incur high direct and indirect economic costs.

Aims:

Describe ITP-related hospitalizations in adult ITP pts receiving romiplostim in clinical practice.

Methods:

Study eligibility criteria and outcomes have been described elsewhere (Wadenvik et al, 2012). Data on ITP-related hospitalizations were collected for up to 2 years before and after romiplostim initiation; bleeding data were collected for up to 6 months before and 2 years after initiation. Informed consent was obtained from all pts. Hospitalization and bleeding rates were calculated with adjustment for the varying observation periods.

Results:

At an interim analysis conducted in September 2012, 310 pts had enrolled; 296 met the study inclusion criteria and were included in the Full Analysis Set. Of these, 44% (n=131) remained on study, 46% (136) had completed the observation period and 10% (29) had withdrawn, with death the most common reason (19 [6%]). At romiplostim initiation, median (Q1, Q3) age, weight and platelet count were 62.0 (46.0, 73.0) years, 75.00 (64.00, 85.00) kg and 19.0 (9.0, 35.0)x109/L. One-third (n=102) of pts were splenectomized, one-third (97) diagnosed <1 year previously (median [Q1, Q3] time since diagnosis 3.56 [0.42, 10.96] years) and 54% (161) female; 54% (159) had received ≥3 prior ITP therapies. Median (Q1, Q3) duration of romiplostim exposure was 65.0 (29.9, 104.9) weeks (maximum 109 weeks); 28% (84) of pts initiated romiplostim at doses above 1 μg/kg/week, 64% (190) received ≥1 romiplostim injection at home and 29% (86) self-administered. Median (Q1, Q3) average weekly dose was 2.8 (1.6, 4.4) μg/kg/week. Median (Q1, Q3) platelet counts rose to 86 (41, 150)x109/L after 4 weeks of romiplostim treatment and remained >50 x109/L thereafter. After romiplostim initiation, the rate of ITP-related hospitalizations, primarily for ITP treatment administration and bleeds, was 2-fold lower; the rate of all bleeds 3-fold lower; and grade ≥3 bleeds rare (Table 1).

Table 1.  ITP-related hospitalizations and bleeding events.

Ten pts reported a total of 13 serious adverse drug reactions (ADRs): 2 events each of pulmonary embolism and myelofibrosis (likely due to the underlying disease [bone marrow metastases in 1 subject each whose initial disease diagnosis was inconsistent with ITP]); 1 event each of acute myeloid leukemia (confirmed by bone marrow trephine biopsy), deep vein thrombosis, drug ineffective (clinical symptoms, thrombocytopenia), myocardial infarction, no therapeutic response (clinical symptoms, bleeding), phlebitis, platelet count decreased (platelets <20x109/L), retinal vein thrombosis, and (reversible) thrombocytosis (platelets 477x109/L). No other thrombotic or bone marrow reticulin ADRs were reported. No fatal ADRs were reported.

Summary / Conclusion:

With similar doses as reported previously (Kuter et al, 2008), and ADRs consistent with the known safety profile, pts with ITP of varying duration and severity receiving romiplostim in routine clinical practice achieved sustained increases in platelet counts and a reduction in ITP-related hospitalizations. The reduction in hospitalizations was likely due to fewer bleeds and less rescue medication/IVIg use, and could offer cost savings in clinical practice. Possible incomplete reporting before romiplostim initiation and imbalanced observation periods should be noted when interpreting these data.

Abstrakta v časopise Haematologica 2013, Suppl1

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