August 20, 2008
Subject enrollment in the ITN's study of immunosuppression withdrawal in pediatric liver transplantation was completed this month, with the enrollment of the 20th and final subject.
The study, led by University of California San Francisco transplant surgeon Sandy Feng, MD, aims to identify immunologic or genetic tests indicating that a patient may be safely removed from immunosuppressive therapy following liver transplantation.
Although increasingly successful at preventing rejection of transplanted organs, immunosuppressive medications are associated with potential side effects, including the risk of serious infections and cancer.
There is growing evidence that, of all transplants, liver transplants may be the most likely to be accepted eventually by the body, without rejection. This state of acceptance is known as "immune tolerance." Scientists, by some estimates, believe that up to 20% of liver transplant recipients may be able to develop this natural immune tolerance and could be removed from their anti-rejection drugs.
"These anti-rejection medications are designed to be taken for a lifetime," said Dr. Feng. "For childhood transplant recipients, this means they are exposed to a lifetime of risk -- a much longer period of time than an adult recipient."
The children (<18 years) enrolled in the study have previously received a living donor liver transplant from a parent at least four years ago. Each will have their anti-rejection medications slowly tapered over a one-year period, under the strict supervision of study physicians. Those showing signs of rejection are placed back on an appropriate immunosuppressive regimen. The primary endpoint for the study will be the proportion of subjects who are able to remain off all immunosuppression for a period of 1 year. Subjects will be followed for up for 5 years. Additional immunologic and genetic tests performed before, during and after withdrawal will be used by the researchers to try to identify markers that indicate a patient may be prone to developing immune tolerance to their transplanted liver.
The study is sponsored by the National Institute of Allergy and Infectious Diseases and is being conducted by the Immune Tolerance Network. In addition to principal investigator Dr. Feng at the UCSF, the study is also being performed by Dr. Udeme Ekong, MD at Children's Memorial Research Center in Chicago and Dr. Steven Lobritto, MD at the Center for Liver Disease and Transplantation Research at Columbia University Medical Center in New York.
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