Eltrombopag for Newly Diagnosed Pediatric Immune Thrombocytopenia Requiring Treatment

Importance: Eltrombopag, a thrombopoietin receptor agonist, is approved by the US Food and Drug Administration for children with chronic immune thrombocytopenia. Efficacy of eltrombopag during the newly diagnosed phase of pediatric immune thrombocytopenia is unknown. Objective: To determine if the proportion of patients with a platelet response is significantly greater in patients with newly diagnosed immune thrombocytopenia treated with eltrombopag than in those treated with standard therapy (first-line treatments). Design, Setting, and Participants: This phase 3, randomized clinical trial enrolled patients (aged 1-<18 years) with newly diagnosed primary immune thrombocytopenia (platelet count <30 × 109/L who required pharmacological treatment but did not have severe bleeding or need a rapid increase in platelet count) from May 7, 2019, to January 25, 2024, at 23 centers participating in the Pediatric ITP Consortium of North America. Final follow-up occurred on February 26, 2025. Interventions: Eltrombopag was administered orally based on a standard dosing schedule (n = 78) vs standard therapy (investigator choice of glucocorticoids, intravenous immunoglobulin, or anti-D immunoglobulin) (n = 40). Main Outcomes and Measures: The primary outcome was a sustained platelet response defined as 3 or more of 4 platelet counts greater than 50 × 109/L during weeks 6 to 12 without rescue treatment. The secondary outcomes included bleeding scores, change in health-related quality of life, and serious adverse events. Results: Of 118 pediatric patients (median age, 8 years [IQR, 4-12 years]; 49% were male), 63% experienced an initial treatment failure after observation or medical therapy. Enrollment ended after a planned interim analysis met a prespecified threshold for efficacy. Of 71 patients in the eltrombopag group, 46 (65% [95% CI, 54%-76%]) had a sustained platelet response compared with 13 of 37 patients (35% [95% CI, 20%-51%]) in the standard therapy group (between-group difference, 30% [95% CI, 11%-49%]; P = .002), which crossed the monitoring boundary for efficacy. Overall, there was no between-group difference in the number and type of adverse events. Conclusions and Relevance: In pediatric patients with newly diagnosed immune thrombocytopenia requiring pharmacological treatment, eltrombopag resulted in a higher rate of sustained platelet response compared with standard therapy. Eltrombopag may be an effective option for pediatric patients with newly diagnosed immune thrombocytopenia with nonsevere bleeding who warrant medical intervention. Trial Registration: ClinicalTrials.gov Identifier: NCT03939637.