Tests Urged on Drugs for ‘Mad Cow’
Two drugs that are effective in treating malaria and some psychotic illnesses may also be able to treat the human version of “mad cow” disease and other related illnesses, and should be immediately tested in human clinical trials, researchers at UC San Francisco said Monday.
The drugs, quinacrine and chlorpromazine, appear to successfully treat mouse cells infected with prions, the researchers said. Prions are the mysterious entities that are believed to cause mad cow disease and related illnesses. They are not living organisms, but are aberrant versions of protein molecules that can be spread from one organism to another and reproduce themselves. The aberrant prions can be toxic, destroying brain tissue and causing illness or death.
The lead author of the study is Dr. Carsten Korth, a postdoctoral fellow in the laboratory of Dr. Stanley Prusiner, who won the Nobel Prize in 1997 for his discovery that prions cause disease.
Quinacrine has been used to treat malaria, while chlorpromazine can treat schizophrenia and other psychotic diseases. The study’s findings, published in Monday’s Proceedings of the National Academy of Science, indicate that quinacrine was more potent than chlorpromazine in the animal tests. However, the schizophrenia drug could be more useful in human clinical trials, Korth said, because it penetrates the blood-brain barrier more easily.
The two drugs were found to prevent the conversion of normal proteins into the deadly form of the prions, Korth said, although the mechanism of the behavior isn’t clear.
What is clear is that they could save people’s lives, he said.
“For prion diseases, no therapy exists,” Korth said. “It doesn’t hurt to take these drugs.”
Prion diseases can arise spontaneously. They also can be genetically inherited or develop through infectious transmission. In the case of mad cow disease, or bovine spongiform encephalopathy--which has infected some herds in Britain--humans can be infected by eating meat from cows that have been infected with prions.
Dr. David Pegues, an epidemiologist at UCLA, called the findings potentially very important, but warned that more studies must be done before testing the drugs on humans.
“Many times we have learned only subsequently that a certain drug had no effect at all” in people, he said. “More studies should be done and documented in a systematic fashion.”
UC San Francisco neurologists plan to conduct a trial in September of the drugs using an undetermined number of patients who have diseases caused by prions, said Dr. Bruce Miller, a UC San Francisco professor of neurology. Miller has helped put together the trial, which has been approved by the federal Food and Drug Administration.
The group plans to work in conjunction with Robert Will, director of the National CJD Surveillance Unit in Edinburgh, Scotland.
Meanwhile, scientists at the Scripps Research Institute in La Jolla also are expected to report later this week on an alternative way of treating prion diseases that so far has been studied only in cell cultures.
