Background: rATG and IL-2RA are the most common induction agents used for KTX. There is no consensus on choice of induction. The aim of this study was to determine the optimal induction based on patient risk profile.

Methods: Prospective, risk stratified, randomized, open label study of 200 KTX. Stratification occurred to insure equal numbers of AAs, PRA >20% and CIT >24 hrs. Pediatric, HLA identical, non-KTX recipients, any positive CMX and age >75 were excluded. All pts randomly received either rATG or IL-2RA in addition to FK, MMF, and corticosteroids.

Results: 200 pts enrolled (102 in rATG and 98 in IL2-RA group), with all pts having at least 1 yr follow-up. Baseline demographics & KTX characteristics were well matched between the 2 groups. Table 1 displays clinical outcomes; AR rates were lower in the rATG group overall, however only time to AR reached significance. All ARs in the rATG group occurred at >150 days post-tx & resulted from reduced immunosuppression or noncompliance. ARs in the IL2RA group were primarily in Black pts (7/10) & occurred at a median 71 days post-tx (4-329). 5/59 pts with a PRA>20% developed AR, 3 in the IL2RA & 2 in the rATG group. Kaplan-Meier analysis of AR w/in the first 6-mo post-tx demonstrates an advantage in Black pts who received rATG, figure 1. CMV syndrome/dz and BKN were higher in the rATG group (15/102 versus 10/98, p=0.39) and occurred mainly in men across the cohort (11/15), with BKN reaching significance. Interestingly, BKN only occurred in men and primarily non-Black men (8/10). Patient and graft survival were comparable between groups. Renal function & tac levels were similar throughout (data not shown).

Conclusion: To date this is the largest, prospective randomized study which demonstrates that under modern immunosuppression and HLA testing, low AR are achievable with IL2RA. There appears to be a racial disparity with Black pts receiving rATG having lower AR w/o an increase in opportunistic infections versus their non-Black counterparts. However, late AR developed in pts who had lower drug exposure from intolerance or non-compliance. These observations should be taken in to account in post-tx management.

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