Real-World Use of Avatrombopag in Children and Adolescents With Immune Thrombocytopenia

Avatrombopag, a second-generation thrombopoietin receptor agonist (TPO-RA), is approved for treatment of chronic immune thrombocytopenia (ITP) in adults and has been studied in a Phase 3 trial in pediatric ITP. The reported efficacy, oral administration, safety profile, and lack of dietary restrictions are appealing treatment characteristics for children. Data on real-world use in children are limited.

This multicenter cohort study included patients diagnosed with ITP at age < 21 years treated with avatrombopag. Clinical features were collected from electronic medical records. Overall platelet response was defined as platelet count ≥ 30 × 10⁹/L and doubling from baseline.

A total of 58 pediatric patients were treated with avatrombopag. Median time from diagnosis to treatment initiation was 4.6 years, with a median of 3 (range 0-11) prior treatments. Overall platelet response was 89.3% with similar response in primary and secondary ITP. Most patients achieved a response on the initial dose. Response rates did not differ by age at treatment initiation. Median time to platelet response was 13.5 days. High-grade bleeding scores were lower after initiation of treatment. Most patients (62%) switched from another TPO-RA to avatrombopag. Response to prior TPO-RA was associated with higher likelihood of response to avatrombopag (OR 15.00, 95% CI 1.824-187.7, p = 0.017). Of 12 patients with no response to prior TPO-RA, 8 responded to avatrombopag. Adverse effects were rare.

In this real-world study, avatrombopag was highly effective at both improving platelet counts and reducing bleeding in children with ITP, even in patients with secondary ITP or who had failed other TPO-RAs.