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

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.

Methods

Between 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.

Results

The 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).

Conclusion

Compared 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.