What are the methods of induction therapy?
Induction strategies can be classified according to the mechanism of the agent used. The two mechanisms that define these agents are lymphocyte-depleting and non-lymphocyte-depleting agents. The lymphocyte-depleting agents used today are rabbit or equine anti-thymocyte globulin (thymoglobulin) and alemtuzumab (humanized anti-CD52 monoclonal antibody, Campath-1H, approved to treat chronic lymphocytic leukemia). Neither agent is approved for induction by the US Food and Drug Administration, despite their widespread use. The non-lymphocyte-depleting agent used is basiliximab (interleukin-2 receptor antibody, anti-CD25). Large pulse doses of steroids are also commonly used at the time of induction in addition to the lymphocyte- or non-lymphocyte-depleting agent. Overall, 85% of transplant programs use induction therapy, most commonly thymoglobulin followed by campath-1H and then basiliximab. Basiliximab is used in those individuals at lower immunologic risk (e.g., Caucasian race, first transplant, older patient, low panel reactive antibody. The benefit is a better safety profile than lymphocyte-depleting agents—in other words, less risk of infection and cancer. Those patients who are at higher risk for rejection should receive induction with a lymphocyte-depleting agent. The most common lymphocyte-depleting agent used today is thymoglobulin. Campath-H1 was the formulation of alemtuzumab sold up until 2012. It is no longer produced, and the remaining supply is used by certain transplant centers until there is no more available. The new formulation of alemtuzumab now in production is called Lemtrada.