Treatment of Immune Thrombocytopenia (ITP) with Eltrombopag - Results of the 4 th Interim Analysis of the German Non-Interventional Trial RISA
Authors: Meyer Oliver , Schlag Rudolf , Stauch Thomas , Fleischmann Bastian , Reiser Marcel , Kaempfe Dietrich , Behlendorf Timo , Welslau Manfred , Willy Claudia , Stauch Martina 
Published: November 2021

Background: Immune thrombocytopenia (ITP) is an acquired autoimmune disorder with increased platelet destruction and impaired platelet production. Patients present with bleeding complications of various severity. Another common symptom of ITP is fatigue, which can severely affect patient's quality of life. Eltrombopag (EPAG) is an oral thrombopoietin receptor agonist, which is proved to be effective and safe in the treatment of ITP. In Europe, it is approved for the therapy of patients who were diagnosed with ITP at least 6 months ago and who have not responded to other treatments. Here we present data from the 4 th interim analysis of the RISA study.

Methods: RISA is a prospective multicenter non-interventional trial in Germany. It was launched in December 2015, and it will be continued until December 2023. In accordance with the inclusion criteria, adults with persisting or chronic pITP (primary ITP) have been enrolled. Patients with pre-treatment could only be included if it was terminated 4 weeks prior to the patient's consent to participate in the study. Exclusion criteria comprised pregnancy, hepatitis C infection and severe aplastic anaemia. Dosage of EPAG and treatment of patients follows the SmPC and the routine of treating physicians. According to the study protocol, patient questionnaires must be completed at 0,1,3,6,9,12,18 and 24 months. Fatigue is assessed using the FACIT-F score, which includes a score range from 0 to 52, with score values &lt;30 indicating severe fatigue. Statistical elaboration is predominantly descriptive. Calculations of confidence intervals and significance values are performed only for explorative purposes.

Results: Data cutoff for this 4 th interim analysis was 23.02.2021. 275 patients were enrolled. 261 of them received at least one dose of EPAG and completed one post baseline assessment. Mean duration of participation was 5.2 years. Mean±SD age was 62.7±17.6 years. 54.8% of the patients were female. Median (range) duration of ITP at baseline was 5.3 (0.0-44.9) years. Comorbidity was present in 80.5% of all patients. 79 (28.7%) patients completed all scheduled visits before data cutoff. Median treatment duration was 395.0 days. Treatment with EPAG was carried out at a median dosage of 50 mg daily.

In 255 patients, baseline platelet counts were available. The proportion of patients with a platelet count ≥50x10 9/L was 30.6% at baseline. With EPAG treatment, it increased to 75.4% within the first month (N=224) and to 89.0% within 24 months (N=73) from baseline. 12.6% of the patients who completed at least one assessment visit after baseline were pre-treated with the thrombopoietin receptor agonist romiplostim. Within this subgroup as well, platelet counts responded well to EPAG treatment.

In 35.6% of patients, at least one bleeding event had occurred in the 12 months prior to baseline. During EPAG therapy, the incidence of bleeding events per patient year was reduced from 1.40 before baseline to 0.60 and 0.13 within the first and second treatment year respectively. This corresponds to a relative reduction in bleeding events of 57% and 91% respectively. Over the entire two years treatment period, the average incidence of bleeding events per patient year accounted for 0.44, which is 69% below the incidence at baseline. Bleeding events were mostly of low severity. (Tab.)

Median FACIT-F score was 37.0 at baseline (N=202; mean 36.0±11.0) and 42.5 after 24 months (N=48; mean 38.1±12.1). This difference was not statistically significant. According to exploratory calculations, severity of fatigue was not correlated to platelet count, hemoglobin concentration or incidence of bleeding events.

Discussion: In line with previously published randomized controlled trials (Birocchi et al. Platelets 2021), this non-interventional study confirmed the effectiveness of EPAG in adults with persistent or chronic ITP in a routine care setting. During treatment with EPAG, the prevalence and severity of thrombocytopenia, as well as the incidence of bleeding events, decreased. We could also confirm that fatigue is a significant issue in patients with ITP. A FACIT-F score of 37.0 is comparable to average score values in cancer patients (Montan et al. Value Health 2018). Under treatment with EPAG, we observed a decrease in fatigue that was clinically relevant but not statistically significant. Further research is needed to explore possible additional effects of EPAG, for example on fatigue.

Figure 1 Figure 1.

Disclosures

Meyer: Swedish Orphan Biovitrum: Consultancy, Honoraria; Grifols: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Stauch: Novartis: Honoraria, Research Funding; Amgen: Honoraria. Willy: Novartis Pharma: Current Employment.