Predicting treatment-free remission after thrombopoietin receptor agonist therapy in immune thrombocytopenia: real-world outcomes from a Korean cohort

Background Thrombopoietin receptor agonists (TPO-RAs) have become a cornerstone in the management of relapsed or refractory immune thrombocytopenia (R/R-ITP), with emerging evidence supporting treatment discontinuation in selected patients. However, predictors of sustained response and real-world switching patterns remain underexplored in Asian populations. Objectives To evaluate clinical outcomes, switching strategies, and predictors of treatment-free remission following TPO-RA therapy in Korean patients with R/R-ITP. Methods We retrospectively analyzed 91 adult R/R-ITP patients treated with eltrombopag, romiplostim (ROMI), or both at a tertiary center in Korea from 2016 to 2021. Clinical responses, platelet count trajectories, loss of response, and sustained response off treatment (SROT) after TPO-RA were assessed. Subgroup analyses identified predictors for response and SROT rates. Notably, Korean reimbursement guidelines mandating drug interruption every 6 months facilitated longitudinal assessment of treatment-free outcomes. Results The overall response rate was 93.4%, and 40% of those achieved SROT after TPO-RA. Higher peak platelet count (platelet count at maximal response > 100 × 10⁹/L; odds ratio, 5.28; P = .005) and prior intravenous immunoglobulin (IVIG) responsiveness (odds ratio, 3.93; P = .036) were significantly associated with SROT. Despite a significantly higher platelet count at maximal response with ROMI, response and SROT rates were comparable between eltrombopag and ROMI, likely reflecting differences in dosing and adherence patterns. Patients with high autoimmune burden or poor IVIG response showed higher loss of response and lower SROT rates. Conclusion TPO-RAs demonstrated robust efficacy and potential for SROT in R/R-ITP. Baseline immunologic status and prior IVIG response may guide treatment selection and discontinuation strategies. These findings highlight the importance of individualized immune thrombocytopenia management and suggest future directions for patients with persistent refractoriness.