James Markmann, MD | Massachusetts General Hospital | Boston, MA

University of California | San Francisco, San Francisco, CA

University of Maryland Medical Center | Baltimore, MD

Massachusetts General Hospital | Boston, MA

New York Presbyterian/Cornell | New York, NY

Hospital at the University of Pennsylvania | Philadelphia, PA

The development of new immunosuppressive agents for use in organ transplantation in humans has resulted in substantial improvements in the survival of grafts and patients over the past 40 years. However, as short-term success becomes more common, long-term side effects are becoming more evident, many of which are due to the immunosuppressive regimens employed. These risks include accelerated cardiovascular disease leading to death, opportunistic infections and malignancy. Other than the need for an increased supply of donor organs, no need is more critical than the need to develop safer, more effective strategies that may ultimately lead to the goal of tolerance and maintain stable graft function without the use of immunosuppressive drugs.

Antithymocyte globulin (ATG) is a polyclonal rabbit antihuman thymocyte globulin approved by the FDA in 1999 for the treatment of acute renal graft rejection in conjunction with concomitant immunosuppression. Despite well documented efficacy over the past decade of ATG in preventing rejection, tolerance induction has not been reported using ATG alone. ATG is a T cell depleting agent which keeps with the general understanding that T cells are a primary contributor to cellular rejection in transplantation. However, a growing number of basic and clinical findings provide the scientific foundation for the hypothesis that B cells play a significant role in both acute cellular and chronic rejection, and that the depletion and expansion of specific B cell subsets may promote tolerance induction.

The goal of this study is to test a new immunosuppressive regimen for human renal transplantation that combines agents that target both the T- and B-cell components of rejection: ATG (T cell) and rituximab, a B-cell depleting agent, with maintenance therapy. This study will evaluate whether this regimen can enable a stepwise withdrawal from immunosuppressive drugs and can promote tolerance.