Scientists mimicked a powerful immune-system disease in creating a pill that may block the rejection of transplanted organs without as many of the side effects that patients now face, researchers reported Thursday.
The experimental drug helped monkeys that had been given kidney transplants _ a crucial hurdle, the researchers said. Although much more research is needed, human safety studies are beginning.
If it works, the drug, created by Pfizer Inc., could mark a more sophisticated way to prevent transplant rejection. Unlike today's anti-rejection drugs, it was engineered to inhibit a molecule called JAK3 that is key to marshaling the immune cells that attack and destroy newly implanted organs.
A lack of JAK3 is at the root of the genetic disease, also called SCID or severe combined immunodeficiency. With the new compound, Pfizer scientists hope to harness JAK3 enough to help transplant recipients without overwhelming the body's defenses.
"It's a brand new concept," said Dr. Dominic Borie, transplant immunology chief at Stanford University School of Medicine, who tested Pfizer's drug in 12 monkeys.
While it completely protected only a third, "it works, and does as well as other immunosuppressive drugs," with fewer side effects, Borie said.
The question is how well the drug will work in people who are already sick instead of monkeys who start off healthy, said Dr. John Fung, transplant chief at the University of Pittsburgh Medical Center, who was not involved with the research.