Study of Alemtuzumab Versus Anti-thymocyte Globulin to Help Prevent Rejection in Kidney and Pancreas Transplantation

Anti-Thymocyte Globulin, rabbit (r-ATG, Thymoglobulin®) is a polyclonal antibody against T-lymphocytes that is used for the prevention and treatment of acute allograft rejection. r-ATG induction therapy is effective in preventing acute allograft rejection, however the usual 7-14 day course involves extensive clinical monitoring and is costly. Recent studies had suggested that smaller cumulative doses are efficacious for induction therapy, and may have an advantage by decreasing the adverse effects associated with the agent (such as leukopenia and thrombocytopenia). Our program subsequently modified our r-ATG induction regimen in November 2001 to give doses on alternate days for at least three doses and has achieved excellent results. However, this regimen is somewhat complex in that it requires central venous access for administration, pre-medication administration to prevent infusion-related reactions, and monitoring of vital signs during each infusion.

Alemtuzumab (Campath®) is a humanized monoclonal antibody to CD52 that is FDA approved for the treatment of B-cell chronic lymphocytic leukemia (B-CLL), but has also been used for immunosuppression induction at the time of solid organ transplant and as anti-rejection therapy. CD52 is present on most lymphocytes, macrophages, monocytes, and NK cells, and causes antibody-dependent cell lysis following the binding of alemtuzumab to the CD52 surface antigen. Alemtuzumab produces significant lymphocyte depletion similar to r-ATG, so some investigators began evaluating it as a preconditioning agent in tolerance protocols (using very low-dose maintenance immunosuppression) in solid organ transplantation. While these studies showed no significant tolerogenic potential for alemtuzumab, one or two 20-30 mg doses of alemtuzumab produced a similar degree of lymphocyte depletion as r-ATG administration. Based on these preliminary data in transplant recipients and prior safety data obtained from safety and efficacy studies of alemtuzumab in patients with rheumatoid arthritis, some US transplant centers changed from using r-ATG to alemtuzumab as their primary induction agent. Most of these centers (notably Wisconsin and Northwestern, where more than 500 kidney and pancreas patients have received alemtuzumab, personal communication Dixon Kaufman, Northwestern) use one or two doses of alemtuzumab for induction, followed by a traditional 2-3 drug maintenance immunosuppressive regimen (rather than the low-dose immunosuppression used in the tolerance protocols).

Knechtle and colleagues from the University of Wisconsin have reported a comparable incidence of acute rejection and favorable graft survival in 130 patients who received a single intraoperative 30 mg dose (+/- an additional dose on post-operative day 1) of alemtuzumab compared with a historical cohort who received r-ATG, OKT3, an IL-2 receptor antagonist, or no induction. In addition, the group found that there was a dramatically lower incidence of acute rejection in the patients who experienced delayed graft function in the alemtuzumab group (9% vs 45% in the control group, p=0.0078).

The use of alemtuzumab as an induction agent in solid organ transplantation is appealing. Only a single intraoperative dose would be required (compared with between 2 and 6 additional doses of r-ATG post-op), thereby eliminating the necessity for central venous access and extensive clinical and nurse monitoring. In addition, the cost of therapy would be less with alemtuzumab than with r-ATG. At WFUBMC, 18 recipients of kidney or kidney/pancreas transplants who received alemtuzumab have had only a 9% six-month rejection rate. Our clinical experience suggests that the agents produce similar results; however, a prospective, randomized study to compare the safety and efficacy of alemtuzumab with r-ATG has not been reported. Also, although alemtuzumab would offer a significant medication cost savings over r-ATG, the impact on the overall cost of care has yet to be established. A comparative study will help us decide if we should make alemtuzumab our new standard of care at this institution.

The purpose of this study is to evaluate the use of alemtuzumab (Campath-1H) for induction therapy in kidney and pancreas transplantation compared to our standard of care, alternate-day r-ATG.