The Impact of IL2ra Induction Therapy in Kidney Transplantation Using Tacrolimus- and Mycophenolate-Based Immunosuppression

Background. IL2 receptor antagonist (IL2ra) induction therapy has gained favor due to an excellent safety profile and improved outcomes in randomized trials using cyclosporine-based immunosuppression. However, there have been no large randomized trials or retrospective analyses examining the effect of IL2ra versus no induction using tacrolimus and mycophenolate (TAC/MPA)-based therapy. Methods. A retrospective analysis from the Scientific Renal Transplant Registry of adult, primary kidney transplant recipients from 2000 to 2008 with initial immunosuppression of TAC/MPA and prednisone, who received IL2ra induction therapy or no induction therapy (n = 28,686) was performed. The primary outcome was acute rejection at 1 year, and secondary outcomes were graft and patient survival at 1 and 3 years. Multivariable analysis was used to control for factors shown to influence the incidence of acute rejection, and separate analyses were performed for deceased versus living donors. Results. Acute rejection at 1 year was significantly lower with IL2ra (11.6%) versus no induction therapy (13.0%; P = 0.001). One-year (95.7% vs. 95.8%) and 3-year (87.5% vs. 87.8%) graft survival, and 1-year (97.4% vs. 97.5%) and 3-year (92.8% vs. 93.2%) patient survival, was not different between those receiving IL2ra and no induction therapy. On multivariable analysis, the relative risk of acute rejection with IL2ra was 0.90 (95% CI, 0.85-0.96; P = 0.001), and the effect was greater in living donors (relative risk, 0.82; P<0.001) than deceased donors (relative risk, 0.95; P = 0.23). Conclusion. The benefit of IL2ra induction with TAC/MPA/prednisone maintenance immunosuppression is less than previously reported due to a low baseline incidence of acute rejection.