Retreatment by Antithymocyte Globulin for Second Kidney Transplantation: Efficacy, Tolerance and Safety

Abstract

Introduction: Antithymocyte globulin (ATG) is composed of rabbit polyclonal-antibodies directed against human T cell epitopes. Whether patients who receive ATG as induction therapy become immunized against rabbit antibodies leading to a diminished efficacy in the case of an ulterior treatment and whether a retreatment by ATG is associated with an increased incidence of cytomegalovirus (CMV) infection and post transplantation lymphoproliferative disease (PTLD) remain to be evaluated in renal transplantation (Tx). Aim: To evaluate efficacy and tolerance of a second induction with ATG in patients who had already received ATG as induction for their 1st kidney Tx. Patients and methods: Retrospective case control study. Fifty four retransplanted patients, who received a second ATG induction between 2004 and 2010 (group 1) were compared to a matched cohort of 108 patients (group 2) who received ATG as induction for a 1st kidney Tx. Match criteria included: age, gender and year of Tx. ATG dose was adapted according to lympho count in a similar way in both groups. Maintenance treatment was the same in both groups. Total dose of ATG, duration of treatment, as well as Leucocyte (leuco), lymphocyte (lympho) and platelet (plat) count were retrieved form patients' files at day 10 and 1, 3, 6 and 12 months after Tx. Incidence of CMV infection and PTLD were also assessed in the two groups. Results:Table: [Results 1]Table: [Results 2]No difference was observed in terms of leuco, lympho and plat depletion. Duration of treatment was similar between both groups suggesting a similar tolerance profile. Dose of ATG was similar in both groups. There was a trend for less CMV infection (including primoinfection and reactivation) in the retreated patients (group 1): 4/54 vs 22/108 in control group (p = 0.11). CMV prophylaxis was similar in both groups. Only one case of PTLD was seen in group 2 (1/108). No PTLD was observed in group 1 during the same period of follow up. Conclusion: 2nd treatment by ATG similarly depletes lymphocytes and is as well tolerated as the 1st treatment. CMV infection and PTLD incidence were not higher in the retreatment group. Further studies are required to evaluate specific T cell subpopulation depletion and to compare long term outcome in patients receiving a 2nd induction with ATG.