Comparison of Chimeric Mouse-Human and Humanized Anti-CD25 Monoclonal Antibodies for Steroid-Refractory Acute Graft-Versus-Host Disease

Xinhui Zheng¹Yunxia Zhou²Ni Lu¹Yawei Zheng¹YIGENG CAO¹Weihua Zhai¹Jialin Wei¹Donglin Yang¹Rongli Zhang¹Aiming Pang¹sizhou feng¹Mingzhe Han¹Erlie Jiang^1*Xin Chen^1*

• ¹Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China
• ²Haihe Laboratory, Tianjin, China

Steroid-refractory acute graft-versus-host disease (SR-aGVHD) represents a severe and persistent complication that can arise following allogeneic hematopoietic stem cell transplantation (allo-HSCT). This study aimed to assess the effectiveness and safety of basiliximab compared with those of a humanized anti-CD25 monoclonal antibody (xenopax) in the treatment of SR-aGVHD in patients who underwent allo-HSCT. This retrospective trial included 32 patients diagnosed with SR-aGVHD who were administered xenopax at 1 mg/kg on days 1, 4, and 8, and weekly thereafter until aGVHD severity was reduced to below grade 2. A historical cohort of 37 patients received basiliximab, which is a chimeric mouse-human anti-CD25 antibody. The overall response (OR) rate on day 28 was not significantly different between The xenopax and basiliximab groups, with rates of 82% and 72%, respectively (p=0.57). Additionally, no differences were observed between the groups regarding the safety profile. The 1-year overall survival (OS) and non-relapse mortality (NRM) rates in the xenopax and basiliximab cohorts were 64% versus 40% (p=0.06) and 45% versus 48% (p=0.46), respectively. In conclusion, no significant differences were observed in efficacy or adverse events between chimeric mouse-human and humanized anti-CD25 monoclonal antibodies for the treatment of SR-aGVHD. Further studies with larger cohorts are necessary to validate these findings.