Long-term efficacy and safety of avatrombopag in Chinese children with primary immune thrombocytopenia: A real-world observational study

Avatrombopag is a newly approved thrombopoietin receptor agonist for second-line treatment of chronic immune thrombocytopenia (ITP) in adults. Our previous study showed its efficacy and safety in a small sample of paediatric ITP patients. However, large samples and long-term data are still lacking. Children diagnosed with ITP and treated with avatrombopag for at least 4 weeks were enrolled. In 94 ITP patients with a median age of 7.43 (interquartile range (IQR), 4.82, 10.80) years, the median effective dose was 10 (IQR, 10, 20) mg for children under 6 years old and 20 (IQR, 20, 40) mg for children under 18 years old. The overall response was achieved in 72.3% (68/94) and 73.4% (58/79) of patients within 4 weeks and 12 weeks. The sustained response at 24 weeks and 48 weeks were 62.3% (33/53) and 51.6% (16/31) respectively. The occurrence of bleeding events, rescue therapy and concomitant ITP medication decreased during the follow-up period. For safety, thrombocytosis (platelet count ≥400 × 10 /L) was the most frequent adverse event (AE) observed in 44 children 97 times. Long-term treatment with avatrombopag in ITP children showed a rapid and sustained platelet response and good bleeding control without significant or new AEs.