Induction therapy after cardiac transplantation: a comparison of anti-thymocyte globulin and daclizumab in the prevention of acute rejection.

Background: Induction therapy with antibodies decreases and delays early allograft rejection. We compared the safety and efficacy of daclizumab and anti-thymocyte globulin (ATG) with respect to the frequency and severity of acute cardiac allograft rejection in heart transplant recipients.

Methods: Forty sequential adult patients were retrospectively studied. In the first 20 patients ATG (2.5 mg/kg daily for 3 to 5 days peri-/and post-operatively) was used as induction therapy and, in the remaining 20 patients, daclizumab (1 mg/kg peri-operatively and every 2 weeks thereafter for a total of 5 doses) was used. A standard triple-drug immunosuppression regimen was administered to all patients.

Results: Baseline characteristics and trough levels of cyclosporine in the 2 groups were similar. During the induction period, defined as the first 3 months, 12 acute rejection episodes requiring treatment (ISHLT Grade > or =2) occurred in the ATG group and 9 in the daclizumab group (p > 0.05). However, the number of biopsies with Grade 1 rejection was increased >2-fold in the daclizumab group (n = 35) compared with the ATG group (n = 17; p = 0.04). The total number of biopsies performed within the first 3 months increased by 26% in the daclizumab group. The number and severity of rejection episodes after 3 months was similar in the 2 groups. The overall occurrence of bacterial infections was significantly higher in the ATG group than in the daclizumab group (p = 0.05).

Conclusions: ATG and daclizumab are equally effective in preventing acute rejections requiring treatment (ISHLT Grade > or =2). Due to the significantly greater frequency of Grade 1 rejections, daclizumab was found to be associated with an increased number of additional biopsies for monitoring rejection status. This implies additional costs to the transplant program, and the long-term implications of the increased number of low-grade rejection episodes remains to be determined.