Platelet Counts Remain Elevated in Two Patients with Idiopathic Thrombocytopenic Purpura after Cessation of Oral Eltrombopag.

Idiopathic thrombocytopenic purpura (ITP) is a disease of inadequate platelet production and increased platelet destruction. Two randomized, double-blind, placebo-controlled trials (TRA100773 A/B) reported that eltrombopag, the first-in-class, oral, platelet growth factor, results in a dose-dependent increase in platelet counts in adult patients with chronic ITP. After treatment of eltrombopag was stopped, platelet counts returned to baseline levels in most patients within 2 weeks, reflecting the normal platelet lifespan (range, 10–14 days). This abstract presents data on two patients enrolled in TRA100773 A/B in whom a prolonged platelet count elevation was observed after cessation of eltrombopag treatment. A 79-year old Asian female (Patient 1) was diagnosed with ITP in September 2003. Prior ITP therapy included prednisolone and Danazol simultaneously in 1997. Prednisolone was stopped after 10 months. Danazol was continued until March 2005 (Day -50). The patient relapsed in March 2005 and received dexamethasone (5 days), IVIg (once), vincristine, and cyclosporin A without a significant response. Eltrombopag treatment was started in May 2005 leading to an increase in platelet counts that remained elevated above 100,000/uL after treatment with eltrombopag was discontinued (Table). Patient 2, a 49-year old Asian female, was diagnosed with ITP in 1997. She relapsed after two courses of dexmethasone 40 mg, QD × 4, administered in September 2003 with a 3-month response and in January 2006 with a 1-month response. Therapy with eltrombopag was initiated in March 2006. As was seen with Patient 1, platelet counts increased after administration of eltrombopag and remained elevated after cessation of eltrombopag (Table). To the best of our knowledge, this is the first report of an ongoing prolonged elevation of platelet counts after cessation of thrombopoietic medication, such as eltrombopag.