A Trial of Eltrombopag or Intravenous Immune Globulin Before Surgery for Immune Thrombocytopenia Patients

Immune thrombocytopenia (ITP) is a heterogeneous autoimmune disease characterized by the presence of platelet autoantibodies, low platelet counts and an increased risk of bleeding. TPO receptor agonists which stimulate platelet production have been shown to be remarkably effective in ITP. Their use as a short-term means of elevating platelet counts in preparation for surgical procedures has not yet been adequately evaluated.

Many patients with moderate to severe ITP (platelet count less than 50 x 10exp9/L) have stable platelet counts and do not bleed; however, when surgeries or invasive procedures become necessary, additional treatment is often required to increase the platelet count to achieve adequate hemostasis. Although specific guidelines for surgical platelet count thresholds in ITP are lacking, platelet transfusion guidelines recommend a platelet count of 50 - 100 x10exp9/L for the vast majority of surgical procedure; 50x10exp9/L is a typical threshold for minor surgeries like tooth extractions and endoscopies; and 100x10exp9/L is used for major surgery like cardiac surgery or neurosurgery.

Commonly, intravenous immunoglobulin (IVIG) is used to rapidly increase platelet counts in ITP patients before an invasive procedure. IVIG is associated with a transient platelet count response in approximately 80% of patients, which occurs within 2 - 4 days. In most patients, platelet counts remain elevated for approximately 4 weeks, allowing enough time to complete the procedure and for adequate post-operative hemostasis. However, IVIG is a resource-intensive and expensive blood product associated with frequent side effects.

Eltrombopag is a small molecule, non-peptide thrombopoietin (TPO) receptor agonist indicated for the treatment of thrombocytopenia in patients with chronic ITP who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. TPO receptor agonists are an effective new class of medications that are non-immunogenic agonists of the TPO receptor (c-Mpl) and work by increasing platelet production in ITP patients. In randomized controlled trials, eltrombopag maintenance therapy has been shown to raise the platelet count in 60 - 80% of ITP patients and platelet counts generally remain elevated as long as the drug is continued. Time to response is 1 - 2 weeks with minimal need for dose titration. Side effects of eltrombopag observed in clinical studies included elevation of liver enzymes (approximately 10% of patients). The risk of thrombosis and bone marrow reticulin formation remain uncertain.

The investigators propose a randomized controlled trial (RCT) involving 74 patients (across approximately 8 centers) in Canada. This study will evaluate the efficacy and safety of eltrombopag bridging therapy compared with IVIG bridging therapy in adult patients with ITP who require surgery. This study will also evaluate bleeding, adverse events and patient-reported treatment satisfaction using the Treatment Satisfaction Questionnaire for Medication (TSQM). Patients will be stratified according to centre and surgery type (major vs. minor).

Inclusion criteria

• Primary or secondary ITP;
• Platelet count below surgical platelet count threshold (50 x10^9/L for minor surgery; 100 x 10^9/L for major surgery);
• 18 years of age or older;
• On stable doses of concomitant ITP medications (i.e the dose administered has not changed) or no ITP medication for at least 2 weeks;
• At least 3-weeks lead time available between randomization and scheduled surgery;
• IVIG and Eltrombopag are acceptable ITP treatment options for this patient;
• Able to provide informed consent.

Exclusion criteria

• Pregnancy or breastfeeding;
• Treatment with IVIG within the last 2 weeks;
• Treatment with a thrombopoietin receptor agonist (eltrombopag or romiplostim) within the last 4 weeks;
• AST, ALT above 2X upper limit of normal;
• Bilirubin above 1.5X upper limit of normal in the absence of clinically benign liver disorder (eg. Gilberts syndrome);
• Deep vein thrombosis, myocardial infarction, thrombotic stroke or arterial thrombosis in the last 12 months;
• History of bone marrow reticulin or fibrosis;
• Known liver cirrhosis;
• Active malignancy (defined as requiring treatment or palliation within the last 6 months);
• Any additional laboratory test result, health related illness or other diagnosis which, in the opinion of the treating physician, may put the subject's health or safety at risk.