Romiplostim for the Treatment of Adults with Primary Immune Thrombocytopenia (ITP) in Routine Clinical Practice in France – Interim Results From a Large Observational Study
Authors: Quittet Philippe , Hamidou Mohamed , Bonnotte Bernard , Fain Olivier , Dillingham Kerry , Kreuzbauer Georg 
Published: October 2019

Abstract
Abstract 4643

Background:
The thrombopoietin-receptor agonist (TPOra) romiplostim is recommended for second-line treatment of adult ITP (Provan, Blood 2010). Romiplostim registration studies were conducted in selected patient (pt) populations and may not reflect clinical practice. Moreover, regional variations may exist in the clinical utility of romiplostim. A recent French study enrolled adult ITP pts failing previous treatments and receiving romiplostim on a compassionate use basis before commercial availability (Khellaf, Blood 2011). We report interim data from French pts enrolled in a large observational study of romiplostim use in clinical practice, with broader inclusion criteria.

Methods:
This ongoing study enrolls ITP pts ≥18 years old, who have received romiplostim in clinical practice. Pts participating in another study, who initiated romiplostim prior to commercial launch or received other TPOra or related products are excluded. Data recorded as per clinical practice is collected for up to 2 years following romiplostim initiation. Study outcomes include pt characteristics (at romiplostim initiation), romiplostim dose, adverse drug reactions (ADRs) and bleeds, summarized for pts meeting the eligibility criteria (Full Analysis Set; FAS). Amgen (Europe) GmbH funded the study and medical writing assistance.

Results:
As of February 2012, 86 (95%) of 91 pts enrolled in France were included in the FAS. Of these, 59% (51/86) remained on study, 31% (27/86) had completed the 2-year observation period and 9% (8/86) had withdrawn (death, 6 [7%]; lost to follow-up, 2 [2%]). At romiplostim initiation, median (Q1, Q3) age, weight and platelet count were 65.0 (48.0, 77.0) years, 74.00 (62.20, 84.00) kg and 18.0 (7.0, 31.0) × 109/L; 38% (33/86) of pts had been diagnosed with ITP for < 1 year (median [Q1, Q3] time from diagnosis, 3.04 [0.51, 13.04] years), 74% (64/86) had received ≥3 prior ITP therapies, 71% (61/86) had received prior rituximab, 30% (26/86) were splenectomised and 52% (45/86) female. Romiplostim was initiated at 1 and ≥3 μg/kg/week in 63% (54/86) and 24% (21/86) of pts; 36% (31/86) of pts stopped romiplostim before the end of the 2-year observation period, with requirement for alternative therapy (11 [13%]), haemostatic platelet count/no further treatment necessary (6 [7%]; last platelet count before romiplostim stopped, 68–616 × 109/L; 1 pt splenectomised, 4 had ITP disease duration of <1 year, all had received 3–5 prior therapies, 1 later received corticosteroids) and ADR (4 [5%]) the most commonly specified reasons. Median (Q1, Q3) romiplostim exposure was 55.1 (29.9, 100.3) weeks (maximum 106 weeks); median follow-up after romiplostim initiation was 20.40 (14.50, 24.10) months. Median (Q1, Q3) average weekly dose over the observation period was 2.6 (1.4, 4.2) μg/kg/week, and 3.02 [2.00, 5.00] and 2.00 [1.14, 3.02] μg/kg/week after 1 and 2 years of treatment (months 10–12 [n=48] and 22–24 [n=23], respectively). Median platelet counts rose rapidly during the first 4 weeks of treatment and remained >50 × 109/L thereafter (Figure). Grade ≥3 bleeds were rare and occurred at a lower rate after romiplostim initiation (Table). The most commonly reported ADRs were thrombocytosis, asthenia, myalgia and headache (9.7–3.2 events per 100 pt-years). Three pts reported a total of 6 serious ADRs: pulmonary embolism, 2 events; deep vein thrombosis, drug ineffective, myelofibrosis (initial disease diagnosis inconsistent with ITP, myelofibrosis more likely due to MDS), and thrombocytosis (platelets 477 × 109/L), 1 event each. No fatal ADRs were reported.

Summary/conclusions:
This study provides further insight into the clinical utility of romiplostim in France. At an interim analysis, pts tended to have less chronic disease than those enrolled in a previous observational study (Khellaf, Blood 2011). With lower doses than reported by Khellaf, and no new safety signals, pts achieved sustained increases in platelet counts and experienced a lower rate of grade ≥3 bleeds following romiplostim initiation.

Disclosures:
Dillingham: Amgen: Employment, Equity Ownership. Kreuzbauer:Amgen: Employment, Equity Ownership.