摘要Background:Steroid-refractory(SR)acute graft-versus-host disease(aGVHD)is the major cause of early mortality after allogeneic hematopoietic stem cell transplantation(allo-HSCT).Xenopax,a novel and the only available humanized interleukin-2 receptor(IL-2R)antagonist,has been approved as a category 2 biological product by the National Medical Products Administration.This study aims to evaluate the efficacy,safety,and prognostic factors of xenopax treatment for SR-aGVHD in real-world settings.Methods:This was a multicenter,retrospective analysis that included SR-aGVHD patients who received xenopax at 17 hospitals across China.The data were collected from the electronic medical records in transplant databases.The primary endpoint was the 28-day overall response rate(ORR),encompassing both partial and complete responses.This study also included independent historical SR-aGVHD cohorts treated with best available treatments(BATs,n=1009)as controls.Results:In total,172 SR-aGVHD patients were included in this study.Xenopax was administered either as monotherapy(n=60)or in combination with other second-line treatments(n=112).The ORR was 64.5%[95%confidence interval(CI)57.3–71.7]on day 28 and 82.6%(95%CI 76.9–88.3)at any time after xenopax treatment.The 2-year probabilities of disease-free survival,overall survival,non-relapse mortality(NRM),and relapse after xenopax treatment were 57.0%(95%CI 49.9–65.0),68.0%(95%CI 61.4–75.4),24.2%(95%CI 18.0–30.9),and 19.0%(95%CI 12.8–25.2),respectively.The ORR and survival were similar between patients with and without prior second-line treatments.The conditioning regimen and human leukocyte antigen disparity did not impact the efficacy of xenopax treatment.According to the multivariate analysis,the presence of grade Ⅲ–Ⅳ aGVHD did not adversely affect the therapeutic response or survival.Xenopax also showed some superiority over BATs in historical cohorts.Conclusion:Our real-world findings suggest that xenopax is an effective and safe treatment for SR-aGVHD.