Eltrombopag as first‐line treatment for thrombocytopenia among paediatric patients after allogeneic haematopoietic stem cell transplantation

Aims The purpose of this study is to examine the safety and efficacy of eltrombopag as first‐line treatment for thrombocytopenia among paediatric patients after haematopoietic stem cell transplantation (HSCT). Methods Forty‐three childhood patients with thrombocytopenia after HSCT who received eltrombopag were retrospectively analysed. Result Eltrombopag was began at the median of 27 days after HSCT and lasted for 24 days. Thirty‐five children responded to eltrombopag therapy, and the cumulative platelet recovery rate was 88.9%. The cumulative incidence of platelet recovery was lower (83.9 vs 100%; P = .035) in patients with decreased numbers of megakaryocytes before starting eltrombopag than in those with normal. Factors associated with a significantly elevated response to eltrobopag from univariate analysis were donor type. Results from the multiple regression analysis found that weight (hazard ratio [HR] = 0.7, 95% confidence interval [CI] 0.5–0.9, P = .022), platelet engraftment time (HR = 1.0, 95%CI 1.0–1.0, P = .012) and bone marrow megakaryocytes (HR = 8.0, 95%CI 1.5–43.3, P = .016) before starting eltrombopag were the independent risk factors. Based on Youden's index algorithm in the receiver‐operating characteristic curve, the optimal cut‐off value of the maintenance dose of eltrombopag in predicting nonresponders was 4 mg/kg. The area under the receiver‐operating characteristic curve was 0.923 with sensitivity of 97.8%, specificity of 87.9%, positive predictive value of 72.3%, and negative predictive value of 92%. None of the paediatric patients stopped using eltrombopag due to side effect or intolerability. Conclusion Eltrombopag is effective and safe in paediatric patients with thrombocytopenia after HSCT. The number of megakaryocytes in bone marrow before eltrombopag treatment may serve as a predictor of the response to eltrombopag. We recommend that the maintenance dose of eltrombopag should not exceed 4 mg/kg/d.