What is the role of romiplostin in the treatment of chronic immune thrombocytopenia (ITP)?

Updated: Jan 11, 2020
  • Author: Craig M Kessler, MD, MACP; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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The TPO receptor agonist romiplostim became available for patients with chronic ITP in 2008. Romiplostinm is administered weekly via subcutaneous injection and increases platelet counts within 5 to 8 days, with levels returning to baseline after 28 days. 

In one prospective, randomized controlled study comparing romiplostin with the standard of care for the treatment of chronic ITP, romiplostim administration was associated with higher rates of platelet count responses, decreased need for splenectomy, fewer episodes of serious bleeding and blood transfusions, and decreased need for initiating additional medical treatments. Romiplostim therapy was also associated with improved quality of life. [62] In a study of long-term romiplostim treatment, a small cohort of children with severe chronic ITP increased and maintained platelet counts for over 4 years, with good tolerability and without significant toxicity. [63]

In a phase III double-blind study of 62 symptomatic children with persistent or chronic ITP who were randomly assigned to receive weekly romiplostim or placebo for 24 weeks, durable platelet response was seen in 52% of patients receiving romiplostim vs.10% of those in the placebo group (p=0.002,906582 odds ratio 9.1). However, further studies are needed to determine long-term efficacy, safety, and remission rates. [64]  

A systematic review concluded that romiplostim is effective and generally well tolerated in patients 65 years of age and older with ITP. Complications included nonsignificant trends toward increased risks of grade ≥3 bleeding and thromboembolic events. [65]

Caveats for the use of romiplostim, and other TPO-mimetics, are as follows:

  • Abrupt discontinuation of these agents, or non-adherence to their therapeutic regimens, can result in a rapid nadir in platelet counts, often to levels that may predispose to catastrophic bleeds.
  • A variable percentage (around 30%) of patients who have achieved complete remission with TPO-mimetic therapy may maintain a durable remission after tapering of the TPO-mimetic. There are no biomarkers or specific patient characteristics that can identify patients who are likely to achieve durable remissions; use in pregnancy is not recommended but anecdotally appears to be safe.
  • Arterial and venous thrombotic events have been reported during TPO-mimetic use, but other than perhaps portal vein thrombosis, such events do not occur any more frequently than in those ITP patients receiving standard non–TPO-mimetic therapy. [66]

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