Efficacy and safety of avatrombopag treatment in immune thrombocytopenia patients in Poland: a multicenter study

Background: Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by platelet counts <100 ×10⁹/L and variable risk of bleeding. Many adults develop chronic disease requiring second-line therapy. Avatrombopag, an oral thrombopoietin receptor agonist (TPO-RA), has demonstrated high efficacy and favorable safety in clinical trials, but real-world data from Poland are lacking. Aims: To evaluate the real-world efficacy, durability, treatment-free remission (TFR), and safety of avatrombopag in Polish adults with primary ITP, and to explore predictors of treatment response. Methods: We conducted a retrospective multicenter study including adults with primary ITP treated with avatrombopag across eight hematology centers in Poland. Responses were defined according to International Working Group criteria and assessed at 1, 3, 6, and 12 months. Univariable logistic regression was used to identify baseline predictors of achieving a platelet response. Results: A total of 142 patients (median age, 54 years) were included. The cohort was heavily pretreated (median of three prior lines of therapy), with 36.6% previously exposed to another TPO-RA. The median baseline platelet count was 21.5 ×10⁹/L. By month 1, 78.3% of patients achieved a platelet response, including 47.8% who achieved a complete response (CR), with a median time to first documented response of 30 days (corresponding to the first scheduled assessment). Among evaluable patients, response rates (CR + R) remained high at 3, 6, and 12 months (84.1%, 90.8%, and 96.8%, respectively). Four patients (2.8 %) achieved TFR with stable platelet counts after discontinuation. Higher baseline hemoglobin levels and lower bleeding scores were associated with achieving a response. Avatrombopag was well tolerated, with infrequent adverse events, one event of hepatotoxicity, and rare thrombotic events. Conclusion: Avatrombopag induced rapid, sustained, and well-tolerated platelet responses in a heavily pretreated real-world Polish cohort. These findings support its use as an effective second-line therapy and highlight the potential for treatment de-escalation, including TFR, in selected patients.