Rabbit Anti–T Cell Globulin in Allogeneic Hematopoietic Cell Transplantation

• Anti–T cell globulin prophylaxis reduces graft-versus-host disease
• Anti–T cell globulin prophylaxis in the setting of marrow or blood stem cell transplantation with myeloablative conditioning does not increase relapse; this may not apply to reduced-intensity conditioning
• Anti–T cell globulin prophylaxis may increase viral infections, particularly Epstein-Barr virus post-transplantation lymphoproliferative disorder

Anti–T cell globulin (ATG) is polyclonal IgG from rabbits immunized with human thymocytes or a human T cell line. Prophylaxis using ATG infused with conditioning for adult marrow or blood stem cell transplantation reduces both acute and chronic graft-versus-host disease (GVHD). However, ATG is not or minimally efficacious in steroid refractory GVHD treatment. Regarding preemptive therapy, ATG is promising; however, further work is needed on establishing adequate biomarkers to be used as triggers for preemptive therapy before it can be used routinely. Relapse is not increased by ATG, except possibly in the setting of reduced-intensity conditioning. Infections are probably increased when using high but not low-dose ATG, except for Epstein-Barr virus–driven post-transplantation lymphoproliferative disorder, which may be increased even with low-dose ATG. Survival is not improved with ATG; however, survival free of immunosuppressive therapy is improved. Pharmacokinetics of ATG are highly variable, resulting in highly variable areas under the time-concentration curves. Optimized dosing of ATG might improve transplantation outcomes. In conclusion, ATG reduces GVHD and, thus, may improve quality of life, without compromising survival.