Purpose: The optimal dosing weight used for rabbit anti-thymocyte globulin (rATG) induction therapy in transplantation continues to lack a consensus. The impact of alternative dosing weights outside of total body weight (TBW) has yet to be evaluated with lower cumulative doses (4.5 mg/kg vs 6-7.5 mg/kg).

Methods: A retrospective, single-center study of 224 adult kidney transplant recipients (KTR) who received rATG for induction immunosuppression from 11/2011 to 12/2015 was conducted. Per institution protocol, patients received rATG 1.5 mg/kg for 3 doses, with an additional dose given to sensitized patients. Patients were stratified by total rATG dose received based on TBW, <4.5 mg/kg (n=115) and ≥4.5 mg/kg (n=109). Incidence of biopsy-proven acute rejection (BPAR), allograft function, incidence of infection and malignancy, and patient and graft survival were analyzed.

Results: Overall, 20 (9%) patients experienced BPAR at 1 year. Patients who received <4.5 mg/kg based on TBW had significantly higher rates of BPAR (13% vs 4.6%, p=0.027) and worse allograft function (eGFR 55 vs 61 mL/min/1.73m², p<0.001) [figure 2] compared to the ≥4.5 mg/kg cohort. Patients who received ≥4.5 mg/kg of rATG had a higher incidence of the combined endpoint of infection and malignancy (34% vs 19%, p=0.012) at 1 year. There was no difference in delayed graft function (DGF), or patient or graft survival between groups.

Conclusion: The findings support the use of TBW as the optimal dosing weight when using 4.5 mg/kg of rATG induction immunosuppression. KTR who received <4.5 mg/kg of rATG based on TBW had significantly higher rates of BPAR and reduced graft function at 1 year.

CITATION INFORMATION: Brueckner A., Logan A., Bowman L. Outcomes Associated with Rabbit Anti-Thymocyte Globulin Induction According to Mg/Kg of Total Body Weight in Kidney Transplant Recipients Am J Transplant. 2017;17 (suppl 3).

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