• The shear-induced platelet activation (SC) is considered as the primary outcome measure. [ Time Frame: When patient has a platelet count between 50,000 and 100,000/µL. ] [ Designated as safety issue: No ]
  

• Rise of reticulated platelets and variation of platelet antibodies. [ Time Frame: When patient has a platelet count between 50,000 and 100,000/µL. ] [ Designated as safety issue: No ]
  

STUDY DESIGN:

Single-center (Medical University Vienna), prospective, controlled study. Patients will be recruited at the Division of Haematology and Haemostaseology at the Medical University in Vienna, one eltrombopag treatment group and 2 control groups, one on standard steroid treatment, another one untreated.

AIM OF THE STUDY:

To determine the effect of MPL agonists on shear-induced platelet activation. Data obtained from patients treated with eltrombopag shall be compared to those from untreated patients and patients on steroids. These investigations will extend previous studies that investigated platelet function without in vitro activation in patients receiving eltrombopag.

PATIENTS:

Trial Population:

Total number of patients n=34: 12 on eltrombopag, 12 on corticosteroids and 10 without treatment will be included in this trial.

Treatment with eltrombopag or corticosteroids. Eltrombopag starting dose: 25 mg/day, increased as needed (to 50 mg or maximum 75 mg once daily) every 2 weeks to reach a platelet count between 50,000-100000/µL and tapering the dosis if platelet count >= 100,000/µL. Afterwards, if platelet count stable (tolerance +/- 20%), platelet control every 4 weeks, otherwise weekly. Prednisolone starting dose: 1 mg/kg/day to reach a platelet count between 50,000-100,000 /µL tapering of the dosage if platelet count >= 100,000/µL.

Laboratory Investigations:

In the eltrombopag group and in the newly treated prednisolone group platelet counts and platelet function tests will be performed at planned visits.

In patients who are on continuous corticosteroids (part of control group I) and untreated patients (control group II), which have a platelet count between 50,000 and 100,000/µL platelet counts, reticulated platelets, platelet function tests and platelet antibodies will be studied at entry and after 4 weeks (+ 5 days).