The Efficacy Of Prophylactic Antithymocyte Globulin In Unrelated Hematopoietic Stem Cell Transplantation

Objective:To explore the efficacy of antithymocyte globulin(ATG)in unrelated allogeneic hematopoietic stem cell transplantation(allo-HSCT)for prophylaxis of graft-versus-host disease(GVHD).Method:We prospectively analyzed 205 unrelated allo-HSCTs from January 2007 to December 2016 in patients with malignant hematological disorders.Allo-HSCT s were classified as follows:HLA-matched transplant without ATG(n=53,group A),HLA-mismatched transplant treated with 6.0 mg/kg thymoglobulin(n=77,group B),and HLA-matched transplant treated with 4.5 mg/kg thymoglobulin(n=75,group C).Result:The medium follow-up time was 48(1-129)months.For groups A and B,the 100-day grade II-IV acute GVHD rates were 37.7%%and 27.3%(p=0.115),the 5-year moderate/severe chronic GVHD rates were 31.9%and 24.2%(p=0.229),5-year relapse rates were 24.5%and 15.8%(p=0.275),the 5-year transplant-related mortality(TRM)were 35.9%and 25.1%(p=0.263),the 5-year overall survival(OS)were 41.5%and 60.0%(p=0.049),the 5-year GVHD-free and relapse-free survival(GRFS)rates were 28.3%and 47%(p=0.021),and the 2-year immunosuppressive therapy(IST)-free survival rates were 8.6%and 40.2%(p=0.0016),respectively.Furthermore,group C had lower incidences of grade II-IV acute GVHD(18.7%,p=0.004),5-year moderate/severe chronic GVHD(16.6%,p=0.028)and 5-year TRM(9.3%,p=0.0008)than group A did.Group C had similar 5-year relapse rate(27.1%,p=0.644),higher 5-year GRFS(52.1%vs 28.3%,p=0.002),2-year IST-free survival(51.7%vs 8.6%,p=0.00004),and 5-year OS(68.3%vs 41.5%,p=0.007)rates than group A did.Conclusions:Therefore,ATG was associated with better GVHD prevention,similar relapse rate,lower TRM,superior OS,GRFS and IST-free survival in unrelated allo-HSCTs.For mismatched unrelated patients,the effect of ATG could overcome declined survival caused by mismatched HLA locus.