496 - Eltrombopag Treatment for Primary and Secondary Thrombocytopenia Post Allogeneic and Autologous Stem Cell Transplantation is Effective and Safe

Abstract

Background: Approximately 5-25% of patients experience inadequate or delayed platelet (primary) recovery following stem cell transplantation (SCT). A few will experience secondary thrombocytopenia, defined as thrombocytopenia after initial platelet recovery without the relapse of decrease. Eltrombopag is a small molecule, thrombopoietin receptor agonist which has been approved for use in Immune thrombocytopenia purpura (ITP) and aplastic anemia. We evaluated our single center experience with safety and efficacy of Eltrombopag in post autologous and allogeneic stem cell transplant recipients. Methods: Between Sept 2014 to May 2017 we retrospectively evaluated 19 patients post autologous and allogeneic SCT for primary and secondary thrombocytopenia. Primary thrombocytopenia was defined as inadequate platelet recovery >20 × 109/L after 21 days requiring transfusions and secondary thrombocytopenia as thrombocytopenia <50 × 109/L after an initial engraftment above 50 × 109/L without transfusions. All patients placed on Eltrombopag had a normal liver function tests (Abormal liver function tests were considered if AST or ALT ≥ 2.5 ULN, or Bilirubin >2 mg/dl). Starting dose was either 25 or 50 mg per day and dose adjustments were per manufacturer's package insert. The primary endpoint was platelet recovery to ≥50,000/mL for 7 consecutive days without transfusion support. Results: Nineteen post-transplant patients were evaluated (Table 1). The median platelet count at the start of treatment was 17 × 109/L. The median time to start of Eltrombopag was 57 days and the median time to primary end point was 41 days. Overall response rate (ORR) in both cohorts was 74%. Six AUTO SCT patients received eltrombopag with 100% response rates. Among the 13 ALLO SCT recipients, 8 patients (61%) responded. The benefit of treatment was seen in patients with adequate and decreased megakaryocytic (MegaK) population (60 and 67% respectively; Figure 1). Both primary (n = 4) and secondary (n = 4) thrombocytopenic patients responded. Transient LFT and bilirubin elevations were noted in 6 patients in both cohorts without the need for discontinuation.Table 1Patient characteristicsFigure 1Promacta response in Allogeneic and Autologous recipientsView Large Image Figure ViewerDownload Hi-res image Download (PPT) The use of Eltrombopag in allogeneic recipients appeared to correlate with increased mortality, as 10 of 13 (77%) allogeneic recipients ultimately passed away from infections (40%), GVHD (40%) or relapse of disease (20%). Conclusion: Eltrombopag improves platelet recovery in in both AUTO and ALLO SCT recipients. In ALLO recipients, Eltrombopag exerted its effect regardless of the Megakrayocytic reserve, however its use correlated with worse outcome in those patients.