Sustained Platelet Improvement Temporally Associated with Dupilumab in Chronic Immune Thrombocytopenia: A Case Study

Introduction

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by reduced platelet counts. Dupilumab, an IL-4 receptor antagonist, is effective in allergic and auto-inflammatory diseases; however, use in ITP remains unexplored. Case Presentation: A 78-year-old male with chronic ITP, maintained on a thrombopoietin receptor agonist (TPO-RA) with an average platelet count of around 78,000/μL, demonstrated a sustained rise in platelet counts (> 100,000/μL) shortly following initiation of dupilumab for an unrelated chronic obstructive pulmonary disease. This improvement enabled a stepwise reduction in TPO-RA to < 20% of his base dosage while maintaining adequate platelet levels for three years since. Despite detailed patient interviews and chart review, we were unable to identify any clinical factors besides commencement of dupilumab as a potential explanation. If indeed causative, we speculate that a TPO-RA-sparing effect of dupilumab might occur via disruption of IL-4 signaling, leading to inhibited Th9 cell activation and subsequent IL-21 production to restore Treg/Th17 balance, thus contributing to decreased platelet destruction.