Lifesaver? a small test at the Toronto outbreak first suggested that interferon a helped SARS patients.
Interferon a , a drug widely used to treat hepatitis C and several cancers, may also work against SARS, according to a study published online this week by Nature Medicine . Clinical studies with the drug should start as soon as possible if SARS reappears, said lead researcher Albert Osterhaus of Erasmus University in the Netherlands.
During the SARS epidemic last year, doctors have tried all kinds of treatments. A combination of an antiviral drug, ribavirin, and steroids - which attenuates the immune response and are often used in other lung infections - has quickly become the standard of care in many countries. Some studies have suggested that patients responded well, but they did, and the blind randomized controlled design that enables researchers to be sure, said Simon Mardel, a doctor working on SARS to the World Health Organization health (WHO) in Geneva. Indeed, some researchers now think the combo of drugs has done more harm than good.
Interferon a , which comes in more than a dozen varieties, is a double hammer. It blocks the replication of several viruses and also activates the immune system. It was first held in 30 of the first patients in the southern Chinese province of Guangdong, but seemed ineffective, a group of Chinese researchers reported recently. A small trial in Toronto, however, released in December, suggested some benefit.
In the new study, cynomolgus macaques received the form of interferon a chemically modified to last longer in the bloodstream. When injected 3 days before infection with the SARS virus, macaques excreted much less virus in their throat and lung damage was reduced by about 80%. When animals received compound 1 and 3 days after exposure, lung lesions was also reduced, but not as much.
This means that the compound would probably be more effective as a prophylactic for, say, family members or patients health care workers at high risk of infection, says Jindrich Cinatl Medical School of University of Frankfurt in Germany. Whether the drug might work in people with the whole SARS remains to be seen, he said.
The lead author of the small Canadian study, Eleanor Fish of Toronto General Research Institute, said she is encouraged by the new results. Already, Health Canada approved a protocol for a human trial with interferon alone, without steroids or ribavirin in SARS reappears. Several other Western countries consider the same course.
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