Recently, The Lancet Haematologypublished a pivotal Phase 3b study (AVA-PED-301) evaluating the efficacy and safety of avatrombopag in a pediatric population.The clinical management of immune thrombocytopenia (ITP) in children has long faced a shortage of convenient and safe oral treatment options. Avatrombopag, an oral thrombopoietin receptor agonist (TPO-RA) that can be taken with food without specific restrictions, is approved for adults with chronic ITP who have had an insufficient response to prior therapy. 

Study Design and Methods

AVA-PED-301 was a global, multicentre, randomised, double-blind, placebo-controlled, parallel-group, phase 3b study. It enrolled children and adolescents aged ≥1 to <18 years with a confirmed diagnosis of primary ITP for at least 6 months and an insufficient response to previous treatment. Eligible patients were randomly assigned (3:1) to receive either avatrombopag or matching placebo. Patients aged ≥6 years received a 20 mg oral tablet once daily, while those aged ≥1 to <6 years received a 10 mg oral suspension once daily. Doses were titrated to maintain a platelet count of 50-150×10⁹/L.

The core phase consisted of a 12-week double-blind treatment period. The primary endpoint was a durable platelet response, defined as at least six out of eight weekly platelet counts ≥50×10⁹/L during the last 8 weeks of the 12-week treatment period, in the absence of rescue therapy. The alternative primary endpoint was a platelet response, defined as at least two consecutive platelet counts ≥50×10⁹/L over the 12-week treatment period, without rescue therapy.

Findings and Safety

Between March 2, 2021, and August 2, 2023, 83 children were screened, and 75 were randomly assigned: 54 to the avatrombopag group and 21 to the placebo group.

• Primary Endpoint: 15 patients (28%) in the avatrombopag group achieved a durable platelet response, compared with none (0%) in the placebo group (difference in response rate 28% [95% CI 16–40]; P=0.0077).

  
  

• Alternative Primary Endpoint: 44 patients (81%) in the avatrombopag group achieved a platelet response, compared with none (0%) in the placebo group (difference 81% [95% CI 71–92]; P<0.0001).

  
  

Regarding safety, the most common adverse events across groups were petechiae (n=20), epistaxis (n=16), and headache (n=14). Serious adverse events were reported in 5 patients (9%) in the avatrombopag group and 1 patient (5%) in the placebo group. No deaths, thromboembolic events, or grade 3 or higher bleeding events were reported.

Interpretation

This study demonstrates that avatrombopag is an effective and safe oral treatment option for children and adolescents with persistent or chronic primary ITP of at least 6 months duration. It showed significant efficacy over placebo and a reassuring safety profile in the pediatric population. Avatrombopag could provide an important new treatment option for pediatric ITP.

Data summarized from: Grace RF, Leblebisatan G, Aydinok Y, et al. Avatrombopag for the treatment of children and adolescents with immune thrombocytopenia (AVA-PED-301): a multicentre, randomised, double-blind, placebo-controlled, phase 3b study. Lancet Haematol. 2025;12(7):E494-E504.