P136 | CLINICAL BENEFITS OF EARLY USE OF AVATROMBOPAG AS FIRST-LINE TPO-RA IN PATIENTS WITH RELAPSED/REFRACTORY CHRONIC IMMUNE THROMBOCYTOPENIA: THE EARLIER YOU START, THE LESS YOU NEED? A SINGLE-CENTER EXPERIENCE.

Introduction: Immune thrombocytopenia (ITP) is a rare autoimmune disorder caused by immune-mediated platelet destruction. After initial treatment with corticosteroids and/or immunoglobulins, second-line therapies for chronic or refractory ITP include thrombopoietin receptor agonists (TPO-RAs) such as eltrombopag, romiplostim, and avatrombopag (Ava), and immunosuppressants like rituximab and fostamatinib. Splenectomy is now rarely performed. Treatment is individualized based on disease severity, comorbidities, and prior response. Patients and Aim: We report our single-center experience with Ava, emphasizing that early use as the first TPO-RA leads to better responses, lower doses, excellent compliance, and cost savings. Ava became available in Sicily in October 2023; from then to December 2024, 24 adult cITP patients (18 females, 5 males) were enrolled (median age 67.5 years, range 28–84). Median disease duration was 11.5 years (range 1–46), with a median of 2 prior treatment lines (range 1–8); three had undergone splenectomy. Baseline median platelet count was 11.5 × 10⁹/L (range 1–28). Results: Among 24 patients, 11 (45.83%) achieved complete response (CR), 9 (37.5%) partial response (PR), and 4 (16.67%) were refractory, with half discontinuing treatment. Notably, 9 achieved CR with very low Ava doses (mean 27.78 mg/week ±17.87; range 10–60 mg), 7 of whom were naïve to TPO-RAs or immunosuppressants. In high responders, thrombocytosis requiring temporary discontinuation and dose reduction occurred, followed by platelet stabilization without thrombosis or toxicities. None had undergone splenectomy. Median baseline platelet counts were higher in high responders (20 × 10⁹/L) than in poor responders (10 × 10⁹/L). Median time from ITP diagnosis was 8 years (range 1–24) vs 13 years (range 1–47), respectively. Among 15 patients requiring higher doses (mean 270.67 mg/week ±24.63; range 210–280 mg), 4 (16.67%) developed deep vein thromboses, leading to permanent Ava discontinuation (Tab. 1). Conclusion: Our findings suggest that significantly lower Ava doses were sufficient for high responders compared to poor responders (p < 0.001), likely reflecting differences in disease severity, prior treatments, and platelet counts. Early Ava use, preferably as first TPO-RA, may achieve better responses with lower doses, improving compliance and reducing thrombosis rate and long-term costs, which can be regarded as an oral alternative to romiplostim.