The problem with minocycline -- which is used to treat acne and urinary tract infections -- and ALS is related to undue extrapolation from animal studies to the human disease, said Dr. Michael Swash, professor emeritus of neurology at Royal London Hospital in England, who wrote an accompanying editorial in the journal.
"The animal model has the human gene in it but lots of copies," he said. "It is not really the same as the human disease."
Animal trials are also untrustworthy because of the size and time of dosages, Swash said. "When the drug is given to mice or rats, the doses are not the same as those given to humans," he said. "Treatment usually starts before the disease commences, so humans get treated a lot later. And human spontaneous ALS does not have the SOD1 mutation, so it is fundamentally different from the animal model."
Effective human trials of treatment for diseases such as ALS should include "a very small number of people, with very good measurements in restricted areas," Swash said. "You need results rapidly to see whether the treatment can be helpful or not. You must find endpoints that are really significant."
Swash said there could be one possible beneficial aspect of the minocycline trial. "Maybe some other drugs we tried that didn't show benefits would show a benefit if used early enough in the disease," he said.
Learn more about ALS from the ALS Association.
SOURCES: Robert P. Bowser, Ph.D., director, University of Pittsburgh ALS research center; Michael Swash, M.D., professor emeritus, neurology, Royal London Hospital, England; Nov. 1, 2007, Lancet Neurology, online
All rights reserved