‘Magic Bullet’ Drug OKd for Kidney Transplants
A new “magic bullet” drug that has proved highly effective in halting the rejection of kidney transplants was approved Thursday by the Food and Drug Administration.
The drug is a so-called monoclonal antibody created from the cells of mice. FDA Commissioner Frank E. Young suggested that the precedent set by the approval will speed consideration of other promising monoclonal antibodies designed to fight cancer as well as the rejection of other transplanted organs.
“This is a pioneer therapeutic product of our new world of biotechnology,” Health and Human Services Secretary Otis R. Bowen said of the drug. It was developed by Ortho Pharmaceutical Corp., based on research by two English scientists who won a Nobel Prize in 1984.
Certain Cells Targeted
Monoclonal antibodies have been dubbed “magic bullets” because they are targeted to act on specific body cells. In the case of the new Orthoclone OKT3, that target is the body’s “T-cells,” white blood cells responsible for the rejection of transplanted kidneys.
Sixty percent of the 7,000 Americans who receive kidney transplants every year require the use of various drugs to try to ward off rejection.
In one trial of Orthoclone, the drug reversed the rejection of newly transplanted kidneys in 94% of the cases, a significant increase over the 75% achieved by conventional drug therapy. Moreover, in another study, Orthoclone halted rejection in 65% of patients who had not responded well to conventional treatment.
The drug “is expected to save thousands of kidneys that might have been lost with traditional therapies,” Ortho said in a statement.
Traditional therapy has involved suppression of the body’s entire immune system (B-cells, controlled by the bone marrow, as well as T-cells, controlled by the thymus). That leaves the patient vulnerable to life-threatening infections.
Risk of Infections
When Orthoclone is injected, “the T-cells disappear from the blood within 15 to 45 minutes” but the B-cells remain active, said Dr. Gideon Goldstein, Ortho vice president of immunobiology. Thus, the drug reverses rejection without suppressing the entire immune system. However, suppression of T-cells does leave the individual vulnerable to certain kinds of infections.
In addition, initial doses of the drug may produce flu-like symptoms such as fever, chills, nausea, vomiting or tremors.
Researchers hope that some day monoclonal antibodies will help cure cancer by delivering toxic drugs only to malignant cells, leaving healthy cells intact.
FDA approval of the safety and effectiveness of Orthoclone “means that we may be able to look at many, many different kinds of cells and regulate the immune system in some very, very exciting ways,” said Dr. Thomas Zuck, head of the agency’s blood products division.
