IMPACT OF IL2-RA INDUCTION THERAPY IN THE PREVENTION OF ACUTE REJECTION WITH TAC/MMF-BASED IMMUNOSUPPRESSION

INDUCTION IMMUNOSUPPRESSION

J. Gralla¹, A. Wiseman^2
1Pediatrics, University of Colorado Denver, Denver/UNITED STATES OF AMERICA, ²Division Of Renal Diseases And Hypertension, University of Colorado Denver, Denver/UNITED STATES OF AMERICA

Body: Introduction: The use of IL2-RA induction therapy has gained favor due to an excellent safety profile and improved outcomes in randomized trials using CsA-based immunosuppression. However, there have been no large randomized trials or retrospective analyses examining the effect of IL2-RA induction vs. no induction using TAC/MMF-based therapy. Methods: Using the SRTR database, we performed a retrospective analysis of 28,686 adult first kidney transplant recipients from 2000-2008 who received TAC/MMF and Prednisone as initial immunosuppression and received IL2-RA (either basiliximab or daclizumab with no other induction agents, n=14,482) or no induction therapy (n=14,204). Primary endpoints were acute rejection at one year and graft survival at 1 and 3 years. Baseline donor, recipient, and transplant factors that have been shown to impact rejection and graft survival were compared among groups and analyzed for potential confounding effects. Results: The 1-year acute rejection rate overall was 12.3%, with acute rejection rates of 11.6% in those who received IL2-RA vs. 13.0% in those receiving no induction (p<0.001). Graft survival rates were not impacted by the use of IL2-RA (Table 1).Table 1: Unadjusted acute rejection at 1 year and graft survival rates in patients on TAC/MMF/Prednisone-based immunosuppression, by IL2-RA vs. no induction

	IL2-RA	No Induction	p-value
Acute rejection at 1 year	11.6%	13.0%	<0.001
Graft survival at 1 year	95.7%	95.8%	0.93
Graft survival at 3 years	87.5%	87.8%	0.50

In unviariate analysis on the use of IL2-RA induction therapy, the relative risk for acute rejection was 0.89, 95% CI 0.84-0.95, p<0.001. While baseline characteristics were statistically different between groups, the magnitudes of these differences were small. Taking into account these variables in multiple logistic regression analysis, the relative risk for the use of IL2-RA induction remained very similar (0.90, 95% CI 0.84-0.97, p=0.003). Delayed graft function, >0 HLA mismatches, recipient race, and recipient age <35 were all strongly associated with an increased risk of acute rejection within the first year post-transplant. Conclusion: The benefit of the use of IL2-RA induction is less clear with TAC/MMF/Prednisone maintenance immunosuppression in preventing acute rejection compared with previously reported results using CsA-based immunosuppression. Recommendations that suggest broad use of IL2-RA should be tempered by these findings in conjunction with the additional costs and the lack of prospective data with commonly used immunosuppression in the current era.

Disclosure: All authors have declared no conflicts of interest.