Scientists said yesterday that two experimental drugs reduce the flare-ups that blur vision, upset balance and impede the movement of people afflicted with multiple sclerosis -- a common neurological disease that only recently was considered untreatable.
A national trial involving one of the drugs, copolymer-1, was directed by the University of Maryland.
Producers of the two drugs plan to ask the Food and Drug Administration next year for commercial approval. Last year, the FDA approved sales of the first drug, Betaseron, ever to show progress against the course of the disease.
Dr. Kenneth Johnson, chief of neurology at the University of Maryland Medical Center, said the developments might herald an era when patients will be able to use more than one medication in a combined assault against MS -- the leading cause of disability among people between the ages of 15 and 45.
"There's a potential to use two drugs that work in entirely different ways, but they would first have to be studied to make sure there are no serious side effects" when they are used together, said Dr. Johnson, who directed a national trial of copolymer-1, a drug made by Teva Pharmaceuticals, an Israeli firm.
Copolymer, which has been under study since the 1960s, was tried by patients at 11 medical centers.
The other drug, interferon beta-1a, is produced by Biogen Inc. of Cambridge, Mass., and clinical trials were directed by the State University of New York at Buffalo. Test results involving the two drugs were announced yesterday at the annual meeting of the American Neurological Association in San Francisco.
While both reduced the frequency of MS attacks, Biogen's drug also slowed the rate at which people accumulated permanent disabilities. Teva's also showed modest success in that regard, but the results were not strong enough to be considered statistically significant.
Nonetheless, the studies encouraged scientists who have watched several decades of painstaking research finally bear fruit.
"These first results are very tantalizing and important," said Dr. Stephen Reingold, vice president for research and medical programs with the National Multiple Sclerosis Society. "What we are facing is the possibility that people will have the possibility of alternative treatments in the future."
"For the patient, this looks very good," said Dr. Walter Royal, a neurologist with the Johns Hopkins School of Medicine. "It looks like things are picking up as far as clinical trials are concerned." He noted that researchers, encouraged by last year's approval of Betaseron, have begun experiments with several other medications.
Multiple sclerosis afflicts between 250,000 and 300,000 people in the United States; about 10,000 new cases are diagnosed each year. The disease occurs when the immune system mistakenly attacks a person's own myelin, the protective sheath around nerve fibers of the brain and spinal cord.
This blocks the transmission of signals to various parts of the body. The effects vary but include blurred vision, numbness, poor balance, paralysis and incontinence. In about a third of patients, the disease follows a "relapsing-remitting" pattern in which people recover all or partial function after each attack.
All three drugs have been tested with varying degrees of success in people suffering from the relapsing-remitting form. The Biogen drug, however, also showed benefits for people with another type -- called relapsing progressive -- in which people tend to recover less function after each attack.
Specifically, the clinical trials showed:
* In the copolymer-1 study, people taking the drug had 31 percent fewer attacks over a two-year period than did those taking a placebo. The study involved 250 people; half took copolymer and half the placebo. In the copolymer group, there were 160 attacks, compared with 210 flare-ups in the placebo group.
Dr. Johnson said fewer attacks mean fewer days of missed work and fewer hospitalizations. Over the course of many years, less frequent attacks may mean that a person worsens more gradually, he said. It might also postpone a stage reached by many patients in their 40s when they begin to decline steeply.
* In the interferon beta study, scientists measured the rate at which symptoms worsened one point on a disability scale of one to 10. In a study of 300 patients, 36 percent of the patients given a placebo progressed one point in two years; this compared with 23 percent of the patients taking the active drug.
Also, magnetic resonance pictures revealed less scarring of brain tissue in people who had taken the active drug. Scientists regard this as physical evidence that the disease has taken a more gradual toll.
Biogen's drug is similar to Betaseron, which is marketed by Berlex, a California firm. Both are based on a natural human protein that seems to buffer the body against assaults by its own immune system. But the Biogen drug is taken weekly, and the Berlex medication every other day.
Dr. Johnson said copolymer appears to stimulate cells that suppress the immune system's attacks against myelin -- but it may have a second mechanism. Its structure is similar to that of a myelin protein, so it may protect nerve cells against attack by serving as a false target.
Despite the flurry of good news, Dr. Johnson cautioned that the drugs are not cures and do not reverse the course of MS. "Patients ask, 'When am I going to feel better?' That is not the purpose," he said. "The purpose is to reduce the number of attacks and the degree of neurologic decline."