Exploratory study on the individualized application of eltrombopag in paediatric immune thrombocytopenia guided by therapeutic drug monitoring

There are variations in individual eltrombopag concentrations that may impact efficacy and adverse drug reactions (ADRs) in paediatric immune thrombocytopenia (ITP). To solve this problem, we tailored the eltrombopag dosage refer to concentration, then followed up to assess concentration value in paediatric ITP. This is a single-centre, prospective, observational study. The eltrombopag dosage was adjusted, and children were divided into three groups: the maintenance, discontinuation, and increase groups. Concentration and other data were compared to explore concentration value in guiding the individualized treatment of paediatric ITP. Thirty-nine patients were enrolled, including 23 in the maintenance group, 3 in the discontinued group and 13 in the increase group. 3 patients discontinued eltrombopag due to ADRs, which was significantly higher than patients in the maintenance group (t = 3.606, p = 0.001). In all, 13 patients increased their dosage due to poor response, whose concentration and platelet count were significantly lower than patients in the maintenance group (t = 2.461, p = 0.019; t = 4.633, p < 0.001). Two months after the increase, the number of patients reaching CR and R respectively increased by 2 and 3, while the median platelet count was significantly raised (Z = -2.411, p = 0.016). Concentration could be used as a reference index for the individualized treatment of eltrombopag in paediatric ITP.