Avatrombopag for the salvage treatment of platelet transfusion refractoriness

Background: Platelet transfusion refractoriness (PTR) is a life-threatening and intractable condition in hematological patients. Thrombopoietin receptor agonists such as avatrombopag promote platelet production and modulate immune intolerance. However, its application in PTR has not been extensively studied. Objectives: We aimed to compare the platelet response (PR) as well as bleeding events and mortality rate between the best available therapies (BATs) and avatrombopag (Ava) treatments in refractory PTR patients. Design: A total of 71 refractory PTR patients were enrolled at Nanfang Hospital. Intravenous immunoglobulin, steroids, and human leucocyte antigen-matched platelet transfusions were administered to 30 patients in the BATs group. The Ava group included 41 patients. Methods: Data of refractory PTR patients were retrospectively collected. The primary endpoint was PR (defined as an increase of platelet count to ⩾50 × 109/L without platelet transfusion support for 7 consecutive days). Secondary endpoints included platelet-transfusion independence rate, cumulative platelet transfusion units, World Health Organization bleeding grades, adverse events, overall survival (OS), and bleeding event-free survival (EFS). Results: There were 75.6% and 13.3% refractory PTR patients who reached PR within 3 months in Ava and BATs groups. The median platelet counts were significantly higher in Ava group from day 7. Platelet-transfusion independence rate in Ava was higher than BATs group. The median cumulative platelet transfusion unit in Ava was lower than that of BATs group. The OS and bleeding events-free EFS rate of Ava group improved within 3 months as compared to BATs group. Cox proportional hazards regression analysis revealed that Ava therapy was a protective factor for the OS and EFS. No primary disease progression or termination of avatrombopag was observed due to intolerability. Conclusion: Our study suggests that avatrombopag is an effective and safe treatment option for refractory PTR patients. Plain language summary Avatrombopag in platelet transfusion refractoriness PTR is a challenging clinical issue in patients with hematologic disorders which increases early death and hospitalization costs. Thrombopoietin receptor agonists have shown inspiring effects in treating thrombocytopenia. However, there are few studies focused on the application of these drugs in PTR patients. In this study, we investigated 71 patients with PTR in which 30 patients received