Monday, October 21, 2013

Induction Therapy in Kidney Transplantation - Summary

Most kidney transplant centers in the United States utilize induction agents as part of their immunosupression protocols. The reasoning behind is that induction therapy has been shown to reduce the rate of acute rejection, however no trial has yet demonstrated an improvement in long-term graft survival.  Induction therapy has also expanded in centers using steroid-withdrawal protocols and in patients with expected delayed graft function due to prolong ischemia time (ECD/DCD kidneys), since calcineurin inhibitor initiation may be delayed (significant vasoconstriction from CNI may potentially delay recovery).

Rabbit antithymocyte globulin (rATG or Thymoglobulin) is the most common agent used in more than 55% of transplant cases in the USA, despite not being FDA-approved for this use (only for treatment of severe cellular rejection). Curiously, rATG is prepared by immunizing pathogen-free
rabbits with a cell suspension of human thymic tissue (thymocytes). After immunization, the serum is harvested from rabbits and immunoglobulins against thymocytes are isolated and subjected to a number of purification processes. Samples from more than 26,000 immunized rabbits are pooled to achieve a high level of batch-to-batch consistency!

Our center uses ATG for induction in high immunological risk patients and Basiliximab for low risk patients in combination with tacrolimus and MMF for maintenance. Steroid withdrawal is performed on most patients by the end of first week post-transplantation, with the exception of highly sensitized patients.

Below a summary table of the 3 most common induction agents in clinical use today, their target cells, dose, cost and side effects.


Antibody Brand Class Lymphocyte depleting Antigenic Target and Cells Typical prescription Side effects
Basiliximab Simulect (Novartis) Monoclonal No IL2 receptor (CD25)
 
Activated T cells
20mg x2 doses  U$4,254 Hypersensitivity reaction (rare)
Rabbit antithymocyte globulin Thymoglobulin (Genzyme) Polyclonal Yes Multiple Ag
 
Mainly T cells, to a lesser extent B and NK
cells
1.5mg/kg
3-7 doses  U$7,824-18,256

Premedicate with steroids and Tylenol


Decrease dose if WBC<3 or="" ptls="" span="">
Fever, chills, dyspnea, nausea, diarrhea,
headache, general pain and pulmonary
edema (cytokine release syndrome)
 
 
Alemtuzumab Campath 1H (Berlex Laboratories) Monoclonal Yes (more prolonged) CD52 Ag

T, B and NK cells, monocytes,

macrophages, dendritic cells, eosinophils,
mast cells
 
30mg x1 dose  U$2,065 Generally none when given
subcutaneously
  

More details about the use of induction therapy in transplantation on this prior blog

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