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Safety and efficacy of long-term treatment of chronic/persistent ITP with eltrombopag: final results of the EXTEND study

Raymond S.M. Wong, Mansoor N. Saleh, Abderrahim Khelif, Abdulgabar Salama, Maria Socorro O. Portella, Paul Burgess and James B. Bussel

Key points

  • Median platelet counts increased to ≥50×109/L by week 2 in ITP patients and were maintained for ≥2 years.

  • Lower platelet counts, more previous therapies, and/or splenectomy resulted in good but somewhat lower responses to eltrombopag.

Abstract

In phase 2/3 trials, eltrombopag treatment for ≤6 months in patients with chronic/persistent immune thrombocytopenia (ITP) increased platelet counts and reduced bleeding. The open-label EXTEND study evaluated long-term safety and efficacy of eltrombopag in adults with ITP who had completed a previous eltrombopag study. For the 302 patients enrolled, median duration of eltrombopag treatment was 2.37 years (2 days to 8.76 years). Median platelet counts increased to ≥50×109/L by week 2 and were sustained throughout the treatment period. Overall, 259 patients (85.8%) achieved a response (platelet count ≥50×109/L at least once in absence of rescue) and 133 of 257 (52%) achieved a continuous response ≥25 weeks. Responses in patients with platelets <15×109/L, more previous therapies, and/or splenectomy were somewhat lower. Thirty-four of 101 patients (34%) on concomitant ITP medication discontinued ≥1 medication. In patients with assessments, bleeding symptoms (World Health Organization grades 1–4) decreased from 57% at baseline to 16% at 1 year. Forty-one patients (14%) withdrew because of adverse events: hepatobiliary adverse events (n=7), cataracts (n=4), deep vein thrombosis (n=3), cerebral infarction (n=2), headache (n=2), and myelofibrosis (n=2) occurred in more than one patient; remaining AEs occurred only once. Rates of thromboembolic events (6%) and hepatobiliary adverse events (15%) did not increase with treatment duration past 1 year. EXTEND demonstrated that long-term use of eltrombopag was effective in maintaining platelet counts ≥50×109/L and reducing bleeding in most patients with ITP of >6 months duration. Important adverse events (eg, thrombosis, hepatobiliary, and bone marrow fibrosis) were infrequent. EXTEND (ClinicalTrials.gov:NCT00351468).

  • Submitted April 6, 2017.
  • Accepted October 4, 2017.