Currently available immunosuppressive regimens for cadaver-kidney recipients are far from ideal because acute-rejection episodes occur in about 30% to 50% of these patients. In the phase III study described here we assessed the ability of basiliximab, a chimeric interleukin (IL)-2 receptor monoclonal antibody, to prevent acute-rejection episodes in renal allograft recipients.

380 adult recipients of a primary cadaveric kidney transplant were randomly allocated, in this double-blind trial, to receive a 20 mg infusion of basiliximab on day 0 (day of surgery) and on day 4, to provide IL-2-receptor suppression for 4–6 weeks (n=193), or to receive placebo (n=187). Both groups received baseline dual immunosuppressive therapy with cyclosporin and steroids throughout the study. The primary outcome measure was incidence of acute-rejection episodes during the 6 months after transplantation. Safety and tolerability were monitored over the 12 months of the study.

376 patients were eligible for intention-to-treat analysis (basiliximab, n=190; placebo, n=186). No significant differences in patient characteristics were apparent. The incidence of biopsy-confirmed acute rejection 6 months after transplantation was 51 (29·8%) of 171 in the basiliximab group compared with 73 (44·0%) of 166 in the placebo group (32% reduction; 14·2% difference [95% Kaplan-Meier CIs 3% to 24%], p=0·012). The incidence of steroid-resistant first rejection episodes that required antibody therapy was significantly lower in the basiliximab group (10% vs 23·1%, 13·1% difference [5·4% to 20·8%], p<0·001). At weeks 2 and 4 post-transplantation, the mean daily dose of steroids was significantly higher in the placebo group (p<0·001 with one-way analysis of variance). The incidence of graft loss at 12 months post-transplantation was 23 (12·1%) of 190 in the basiliximab group and 25 (13·4%) of 186 in the placebo group (1·3% difference [−5% to 9%], p=0·591). The incidence of infection and other adverse events was similar in the two treatment groups. The acute tolerability of basiliximab was excellent, with no evidence of cytokine-release syndrome. 14 deaths (basiliximab n=9; placebo n=5; −2·0% difference [−6% to 2%], p=0·293) occurred during the 12-month study and a further three deaths (basiliximab n=1; placebo n=2) occurred within the 380-day cut-off period. One post-transplantation lymphoproliferative disorder was recorded in each group.

Prophylaxis with 40 mg basiliximab reduces the incidence of acute rejection episodes significantly, with no clinically relevant safety or tolerability concerns.