An experimental drug that selectively tamps down part of the immune system can offer dramatic relief to many victims of the painful bowel disorder Crohn’s disease, and might also work against illnesses such as arthritis and multiple sclerosis, researchers say.
Other drugs are already available against Crohn’s, but their effectiveness is spotty. This is the first study to show that a certain immune system protein could be key to the poorly understood disease.
In the small, preliminary study, researchers at the National Institutes of Health and other sites found weekly injections ABT-874 reduced symptoms in as many as three-quarters of patients, or three times better than dummy injections.
“A lot of work has to be done, but it’s very exciting,” said Dr. Richard MacDermott, director of Albany Medical Center’s inflammatory bowel disease center and scientific consultant to the Crohn’s and Colitis Foundation of America.
The drug’s maker, Abbott Laboratories, has not yet decided whether to conduct further tests and seek approval of the drug, spokesman Jim Bozikis said.
Battling autoimmune diseases
Researchers believe Crohn’s disease is triggered when the immune system, for unknown reasons, overreacts to harmless bacteria normally present in the intestines and attacks tissue there. Symptoms include diarrhea, abdominal pain, fever and weight loss.
An estimated 500,000 to 1 million Americans have the disorder. There is no cure. The treatments now on the market do not work in some patients. Many stop working after awhile. And they all have side effects, ranging from diabetes, cataracts and high blood pressure to liver, pancreas and kidney problems.
The study was reported in Thursday’s New England Journal of Medicine.
Lead researcher Dr. Peter Mannon, head of clinical inflammatory bowel disease research at the National Institute of Allergy and Infectious Diseases, said he believes that in Crohn’s patients, the body makes too much of three immune system substances, including the protein interleukin-12. Those substances then attack tissue in the digestive tract.
Mannon said the experimental drug appears to bind to and shut down interleukin-12, an immune system “messenger” that attacks perceived invaders and summons other immune cells to the battle.
The 79 patients tested had moderately severe Crohn’s symptoms. Some received dummy injections, some got seven 1-milligram doses and some 3-milligram doses. Some got their seven injections staggered over 11 weeks, others had them weekly.
Those getting weekly 3-milligram doses fared best: Seventy-five percent had reduced symptoms and 38 percent were in remission when treatment ended. After 11 more weeks of follow-up, 69 percent still had reduced symptoms and 38 percent were still in remission.
“It looks like a small subgroup of patients with Crohn’s disease might be benefited by this type of treatment,” but it would be expensive, said Dr. Kiron Das, director of the Crohn’s and Colitis Center of New Jersey at Robert Wood Johnson Medical School.
More studies needed
He said long-term studies are needed because the drug’s effects appeared to wear off after patients stopped taking it. Also, the safety of long-term use must be determined because several patients had side effects, including injection-site reactions and increased Crohn’s symptoms, he said.
Researchers said the drug could also prove effective against rheumatoid arthritis, multiple sclerosis and psoriasis — which, like Crohn’s, are autoimmune diseases in which the immune system goes haywire and attacks a person’s own tissue. Abbott already is testing the drug on patients with MS.
But experts warned that the drug might worsen respiratory conditions such as asthma and, because it suppresses the immune system, increase the risk of infections.
In an accompanying editorial, Dr. Fabio Cominelli of the University of Virginia Health Sciences Center wrote that despite limitations, this type of therapy “is an important staging post on the road to a cure for Crohn’s disease.”
Abbott and its former partner in developing the drug, Wyeth, paid for the study. Most of the researchers have served as consultants for drug companies, and three hold a related patent.