Interferon a No-Go for Pulmonary Fibrosis
But it may offer some help to those with mild forms of the fatal lung disease
WEDNESDAY, Jan. 7, 2004 (HealthDayNews) -- A once hopeful treatment for pulmonary fibrosis, a fatal disease of the lungs, appears to have little or no effect on progression of the disease or on quality of life, a new study has found.
There remains some optimism, however, that the treatment, interferon gamma-1b, might benefit patients with mild to moderate symptoms of the disease. The authors of the study, which appears in the Jan. 8 issue of the New England Journal of Medicine, are launching a new trial to test this hypothesis.
The median survival time for patients diagnosed with pulmonary fibrosis is only two to three years. The disease results in a scarring of the lungs that eventually prevents the lungs from fulfilling their primary mission of delivering oxygen to the body. The only effective treatment is lung transplantation, although many people are treated with anti-inflammatory and immunosuppressive drugs, both of which have side effects.
"There are some medicines which have anecdotally improved patients, [but] for the vast majority of patients this is a devastating illness," says Dr. Alvin S. Tierstein, a professor of medicine at Mount Sinai School of Medicine in New York City and author of an accompanying editorial in the journal.
"It just progresses and progresses, and nothing that we have helps," he adds. "A huge number of patients are on the transplant list waiting for lung transplants, which usually take about two years to come through, and most of the patients die on the list waiting."
A study published in 1999 reported that nine patients treated with interferon gamma-1b and prednisolone did experience improvements.
Those results essentially provided the impetus for the current study, which was funded by InterMune Pharmaceuticals Inc., maker of interferon gamma-1b. Dr. David Schwartz, one of the principal investigators on the new study and chairman of the pulmonary allergy and critical care division at Duke University Medical Center, has been a paid consultant for InterMune since 2000.
Scientists thought interferon might have an effect by decreasing the production of collagen, which is a key component of the scarring, Schwartz says. "The concept was that interferon gamma would downregulate the disease-causing factors that perpetuate this process in the lungs," he explains.
Schwartz and his colleagues randomly assigned 330 patients with idiopathic pulmonary fibrosis -- whose cause is unknown -- to receive either interferon gamma treatment or a placebo. The participants were located at medical centers in the United States, Europe and South Africa. Treatment was administered three times a week for just over a year.
The interferon treatment did not slow the progression of the disease, nor did it have a significant effect on lung function or quality of life. "There was no change at all. So in those terms this is a negative study and it has to be represented that way," Tierstein says. "I don't think we should fool anybody and say this medicine makes you better."
Still, there are some potential silver linings in this cloud. For one thing, over the course of the study, only 10 percent of the patients in the interferon gamma group died, compared to 17 percent in the placebo group.
"It is conceivable that interferon is affecting other things," Tierstein says. "We know that interferon is important in the control of infections and it may be that we're preventing infections from carrying these patients off."
Also, patients with milder symptoms lived longer when receiving interferon gamma than similar patients in the placebo group. Among participants with mild pulmonary fibrosis, 3.5 percent receiving the drug treatment died versus 12.5 percent in the placebo group.
"It may be, since all the medicines we have are toxic, we tend not to treat until we have no choice and pulmonary function is really bad," Tierstein says. "Maybe we're waiting too long. Maybe we should treat earlier."
Adds Schwartz: "There is some hope that it [interferon gamma] still will work. In fact, we're in the process of launching a major study to look at the effect of this drug in individuals with mild to moderate disease. If anything, it looks like we focused on everyone with pulmonary fibrosis when we should have focused on those with mild to moderate disease."
That study, which will follow participants for up to four years, will be looking primarily at survival rates.