Reduction of the occurrence of acute cellular rejection among renal allograft recipients treated with basiliximab, a chimeric anti-interleukin-2-receptor monoclonal antibody. United States Simulect Renal Study Group.

BACKGROUND: A double-blind, placebo-controlled phase III study was performed to assess whether basiliximab, a chimeric anti-interleukin-2 receptor monoclonal antibody, reduced the incidence of acute rejection episodes in renal allograft recipients.

METHODS: A total of 348 patients were randomized into two demographically matched, equally sized groups treated with either basiliximab or placebo. The dose of basiliximab-20-mg infusions on day 0 and day 4-was selected to block detection of interleukin-2 receptor on 97% of peripheral blood lymphocytes for 30-45 days. All patients received immunosuppressive therapy with cyclosporine microemulsion (Neoral) and steroids. An intent-to-treat analysis of 1-year data assessed the incidence of posttransplant acute rejection episodes, patient and graft survival rates, and the safety and tolerability of basiliximab.

RESULTS: Among the eligible 346 patients equally divided into the two treatment groups, basiliximab reduced the proportion of patients who experienced biopsy-confirmed acute rejection episodes by 28%: 61 (35.3%) basiliximab vs. 85 (49.1%) placebo (P=0.009). Graft losses occurred in 9 (5.2%) basiliximab-treated and 12 (6.9%) placebo-treated patients. Five (2.9%) deaths in the basiliximab group and seven (4.0%) in the placebo group occurred. Compared with placebo, a higher fraction of basiliximab patients produced urine in the operating room, and a significantly lower fraction had renal dysfunction in the first month (serum creatinine > or =5 mg(dl) and between 1 and 12 months (serum creatinine > or =3 mg/dl). During the first 12 months, 94 (54%) basiliximab-treated patients experienced serious adverse events, compared with 106 (61%) who received placebo.

CONCLUSIONS: Prophylactic basiliximab therapy is well tolerated, has an adverse event profile comparable to placebo, and significantly reduces the number of acute rejection episodes in renal allograft patients within the first year after transplantation.