Gene mutation increases drug toxicity, rejection risk in pediatric kidney transplants

February 18, 2009

Screening for mutations in a gene that helps the body metabolize a kidney transplant anti-rejection drug may predict which children are at higher risk for side effects, including compromised white blood cell count or organ rejection, according to new research.

Published online Feb. 18 by the Nature journal Clinical Pharmacology and Therapeutics, the study suggests this genetic approach could also help physicians tailor personalized anti-rejection drug doses to prevent adverse reactions, said senior investigators Alexander A. Vinks, Pharm.D., Ph.D., and Jens Goebel M.D., of Cincinnati Children's Hospital Medical Center.

"There are better ways than just giving standard doses of these drugs, and in due course these types of technologies will be available worldwide to help patients," said Dr. Vinks, director of the Division of Clinical Pharmacology and the Pediatric Pharmacology Research Unit at Cincinnati Children's. "This pilot study shows personalized and prospective MMF dosing and monitoring may be feasible to reduce the high incidence of drug toxicity in children without compromising the drug's protective effects against kidney graft rejection."

MMF, or Mycophenolate Mofetil, is an immunosuppressive agent commonly used to prevent rejection in organ transplants, particularly in kidney transplants. After taken orally, the drug is quickly processed by the body into active form. During this time, patients with a specific point mutation in the gene that helps break down the drug, UGT, metabolize the drug slower. This point mutation, called UGT1A9-331, causes overexposure and adverse side effects in the affected children, the study concluded. UGT encodes the drug's main metabolizing enzyme in the body, uridine diphosphate-glucuronosyl transferase.

Adverse side effects most commonly linked to MMF have included gastrointestinal complications (such as diarrhea) or leukopenia - a drop in white blood cell count that can put patients at higher risk for infections. In some instances, patients have to be taken off the drug or have their dosage reduced to the point where they risk rejection of the new organ.

The current study analyzed 38 children who had received kidney transplants. Sixteen of the children experienced adverse side effects from MMF therapy. In the adverse reaction group, nine children with the specific UGT point mutation developed leukopenia. The researchers found no strong association between UGT gene variants and diarrhea - the most common side effect linked to MMF - suggesting gastrointestinal reactions to the drug may be caused by other factors.

Some previous studies have linked UGT gene mutations and MMF-related side effects in kidney transplant recipients, while others have suggested a greater risk for adverse events in children. A review of earlier research combined with their current data led researchers in this study to conclude that pediatric kidney transplant recipients on MMF therapy have a significantly higher likelihood of drug-related complications than adult patients. One previous study compared 22 pediatric and 37 adult transplant recipients, all who started with the standard recommended doses of MMF. Among the children, 54.5 percent experienced adverse side effects compared to 21.6 percent of the adults.

Besides the UGT1A9-331 point mutation, other studies have also linked a second variation, called UGT2B7-900, to possible MMF overexposure and development of leukopenia, said Tsuyoshi Fukuda, Ph.D., co-author on the current study and a colleague in Dr. Vinks' division at Cincinnati Children's. The research team recently completed pharmacokinetic and biomarker studies - which analyze how the body metabolizes a drug - to solidify the connection between different variants of UGT and MMF overexposure in pediatric kidney transplant patients.

Researchers want to use data from these pharmacokinetic studies as a basis for showing whether increased MMF exposure in adults can also be linked to specific variations in the UGT gene, according to Dr. Fukuda.

The pilot study is part of the growing field of genetic-based pharmacology, or pharmacogenetics. Combining biology and information technology, researchers are developing computer-based algorithms that allow taking a few drops of blood and analyzing how quickly a person's body will break down and absorb a drug based on their genetic makeup. The goal is to reduce drug-related side affects by optimizing drug doses for individual patients.

Source: Cincinnati Children's Hospital Medical Center

Explore further: Drug yields high response rates for lung cancer patients with harsh mutation

Related Stories

Drug yields high response rates for lung cancer patients with harsh mutation

October 18, 2017
A targeted therapy resurrected by the Moon Shots Program at The University of Texas MD Anderson Cancer Center has produced unprecedented response rates among patients with metastatic non-small cell lung cancer that carries ...

The big question: Will cancer immune therapy work for me?

September 20, 2017
Dennis Lyon was a genetic train wreck. Cancer was ravaging his liver, lungs, bones and brain, and tests showed so many tumor mutations that drugs targeting one or two wouldn't do much good. It seemed like very bad news, yet ...

Cancer drug may benefit patients with inherited form of kidney disease

August 24, 2017
A cancer drug called bosutinib may inhibit the growth of cysts in patients with autosomal dominant polycystic kidney disease (ADPKD), according to a study appearing in an upcoming issue of the Journal of the American Society ...

New approach to genetic testing leads to dramatic response in MET fusion lung cancer

August 30, 2017
There are many ways a gene can be altered and there are many genes that, when altered, can cause cancer. Testing individually for each possible alteration in every cancer-related gene is not feasible as it would require hundreds ...

Combating antiviral drug resistance with dynamic therapeutics

August 24, 2017
Antiviral drug resistance has long been a problem in modern society. As viruses evolve, they develop resistance to antiviral drugs, which become less effective at treating diseases such as influenza.

Meds by monthly injection might revolutionize HIV care (Update)

July 24, 2017
Getting a shot of medication to control HIV every month or two instead of having to take pills every day could transform the way the virus is kept at bay.

Recommended for you

Inflammation trains the skin to heal faster

October 18, 2017
Scars may fade, but the skin remembers. New research from The Rockefeller University reveals that wounds or other harmful, inflammation-provoking experiences impart long-lasting memories to stem cells residing in the skin, ...

Large variety of microbial communities found to live along female reproductive tract

October 18, 2017
(Medical Xpress)—A large team of researchers from China (and one each from Norway and Denmark) has found that the female reproductive tract is host to a far richer microbial community than has been thought. In their paper ...

Study of what makes cells resistant to radiation could improve cancer treatments

October 18, 2017
A Johns Hopkins University biologist is part of a research team that has demonstrated a way to size up a cell's resistance to radiation, a step that could eventually help improve cancer treatments.

New approach helps rodents with spinal cord injury breathe on their own

October 17, 2017
One of the most severe consequences of spinal cord injury in the neck is losing the ability to control the diaphragm and breathe on one's own. Now, investigators show for the first time in laboratory models that two different ...

Pair of discoveries illuminate new paths to flu and anthrax treatments

October 17, 2017
Two recent studies led by biologists at the University of California San Diego have set the research groundwork for new avenues to treat influenza and anthrax poisoning.

New method to measure how drugs interact

October 17, 2017
Cancer, HIV and tuberculosis are among the many serious diseases that are frequently treated with combinations of three or more drugs, over months or even years. Developing the most effective therapies for such diseases requires ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.