Influence of Lower Dose Antithymocyteglobulin As Conditioning Regimen on Viral Infection after Haploidentical Allogeneic Stem Cell Transplantation

Abstract

▪Background: Antithymocyteglobulin (ATG), used as conditioning regimen, can reduce graft-versus-host disease (GVHD) in haploidentical hematopoietic stem cell transplantation (haplo-HSCT). Notwithstanding, immunosuppressive effect of ATG may increase the risk of viral infections after HSCT. To evaluate the effect of different doses of ATG on post-transplant viral infection, we conducted a multicenter prospective study to compare EBV and CMV infection in haplo-HSCT recipients receiving 7.5 mg/kg or 10 mg/kg ATG.MethodsBetween May 2013 and November 2015, 350 consecutive patients with hematological malignancies undergoing haplo-HSCT were randomized in 5 hospitals. One hundred and seventy-two patients received ATG with a total dosage of 7.5 mg/kg and 175 received 10 mg/kg ATG. Three patients did not received allocated intervention and transplantation due to leukemia relapse before transplant or toxicity of conditioning regimens.ResultsThe cumulative incidence of EBV viremia on day 180 was 23.3±3.2% in 7.5 mg/kg ATG arm which was lower than that in 10 mg/kg arm (34.6±3.7%, P=0.037). CMV viremia were comparable in the two arms (7.5 mg/kg arm: 79.0±3.1% vs. 10 mg/kg arm: 76.9±3.2%, P=0.950). The incidences of CMV diseases were 0.6±0.6% and 2.4±1.2% in 7.5 mg/kg and 10 mg/kg arms, respectively (P=0.093). No difference in the incidence of post-transplant lymphoproliferative disorder (PTLD) was found between the two arms (2.4±1.2% in 7.5 mg/kg arm vs. 5.4±1.8% in 10 mg/kg arm, P=0.150). Besides, acute GVHD grade II to IV within 100 days occurred in 55 recipients with the incidence of 31.4% in 7.5mg/kg ATG arms and 45 recipients in 10 mg/kg arms with the incidence of 26.2% (P=0.279). The incidences of aGVHD grade III to IV were similar in the two arms (8.0% in 7.5 mg/kg arm: vs. 4.7% in 10 mg/kg arm, P=0.196). The 2-years overall survival were 69.5±4.7% and 69.4±3.9% for 7.5 mg/kg and 10 mg/kg group (P=0.540).ConclusionCompared with 10 mg/kg of ATG, the application of 7.5 mg/kg might reduce the risk of EBV infection after haplo-HSCT and not increase aGVHD. DisclosuresLin:National Natural Science Foundation of China 81270647: Research Funding; Science and technology planning project of Guangdong Province 2014B020226004: Research Funding; The project of health collaborative innovation of Guangzhou City 201400000003-4: Research Funding; National Natural Science Foundation of China 81400141: Research Funding.