Analysis of the Efficacy of Avatrombopag for the delayed platelet engraftment after Allogeneic Hematopoietic Stem Cell Transplantation for aplastic anemia

xinhe Zhang¹Jia Feng¹Zhengwei Tan¹Herui Zhang¹Huijin Hu²Yuechao Zhao²Dijiong Wu²Yu Zhang²Liqiang Wu²Tonglin Hu²Zhengsong Yan²Baodong Ye²Wenbin Liu^2*

• ¹The First Clinical College of Zhejiang Chinese Medical University, Hangzhou, China
• ²The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, China

Background: Delayed platelet engraftment (DPE) after allo-HSCT lacks standard therapy. Avatrombopag (AVA), a second-generation TPO agonist, is often delayed until transfusion-related events occur, potentially harming high-risk recipients.We compared recombinant human thrombopoietin (rh-TPO) with early AVA switching for treating DPE in aplastic anemia (AA) patients post-allo-HSCT to optimize management strategies.Methods: This single-centre study retrospectively enrolled 154 consecutive AA patients receiving allo-HSCT at Zhejiang Provincial Hospital of Traditional Chinese Medicine (March 2019-September 2023). Of these, 39 deemed high-risk for poor platelet engraftment (advanced donor/recipient age, low CD34+ dose, etc.) were non-randomly assigned: (1) AVA group (n = 11), switched to avatrombopag if platelets remained <30×10⁹/L on day +14 or <50×10⁹/L on day +21; (2) rh-TPO group (n = 28), continued rh-TPO monotherapy. Allocation followed clinician judgment and patient consent.Results: Our findings revealed that the 1-year overall survival (OS) rate was notably higher in AVA group (100% vs 78.6%, P=0.106). And the complete remission (CR) rate in the AVA group was significantly higher than that in the rh-TPO group at 3 and 6 months after transplantation(100% vs 67.9%, P=0.032; 100% vs 71.4%, P=0.047). At 3 months post transplantation, the platelet engraftment rate in the AVA group was significantly higher than that in the rhTPO group (67.9% vs 100%, P= 0.04). The median time to achieve platelet engraftment was 20 (13, 25) days for the AVA group and 23 (10, 68) days for the rh-TPO group. Additionally, the AVA group reached platelet counts of 30, 50, and 125 × 109/L more rapidly than the rh-TPO group. Furthermore, at 3 months post-transplantation, the median platelet transfusion volume of AVA group was less than rh-TPO group(63U vs 82U, P=0.141).For patients identified as being at high risk for poor platelet engraftment following allo-HSCT, early transition to AVA can significantly reduce the duration of DPE and promote platelet recovery post-transplantation. This strategy has the potential to enhance patient survival rates and overall outcomes.