American Foundation for AIDS Research, August 2003
Kristen Kresge

When Severe Acute Respiratory Syndrome, or SARS emerged, scientists were quick to draw on the knowledge and technology developed while working with HIV. Soon after identifying the new human virus, their focus shifted to finding effective drugs to treat SARS. It may be here that HIV research will make the most critical contribution to fighting this new disease.

Several prominent AIDS researchers from the United States began by looking at approved HIV drugs in test-tube studies that evaluated their activity against the coronavirus associated with SARS. Among these scientists was Dr. David Ho, Scientific Director of the Aaron Diamond AIDS Research Center in New York City.

“Ho screened a whole lot of drugs,” observed Dr. Malik Peiris, head of Virology at the University of Hong Kong. Peiris worked along with Ho in the Hong Kong laboratory designated by the World Health Organization for SARS research.

Merck Research Laboratories in New Jersey and Pennsylvania meanwhile is pursuing both new drugs and vaccines for SARS. Dr. Emilio Emini, Senior Vice President of Vaccine Research at Merck, confirmed in an interview that the SARS coronavirus had two proteins likely to be proteases – an enzyme that is also essential in HIV replication. But Emini, a pioneer of the protease inhibitor program for HIV, predicted that new drugs would be needed to act against the SARS enzymes. “Available protease inhibitors are unlikely to be effective,” he said. Protease inhibitors have to be capable of fitting into the protease molecules as a key does into a lock, and the structure of the two viruses’ proteases differ considerably.

But the initial laboratory work by Ho and Peiris found that the anti-HIV protease inhibitor Kaletra was indeed active against the SARS virus. It is not known whether the drug acts in the same way against both HIV and SARS.

A formal human clinical trial in Hong Kong is now testing Kaletra’s effectiveness in SARS patients. Study participants receive ribavirin along with Kaletra. Ribavirin is an antiviral agent approved for hepatitis C and severe cases of respiratory syncytial virus. In the late 1980s, ribavirin was tested against HIV but seemed ineffective.

Peiris says that the Kaletra/ribavirin combination is proving more effective than ribavirin alone. Hong Kong researchers reported at a June 14 medical symposium that 130 SARS patients treated with Kaletra plus ribavirin experienced a 50% reduction in death rate.

The combined side effects of Kaletra and ribavirin will be an important issue. Even in short courses, Kaletra causes considerable digestive upset while ribavirin reduces red blood cell counts and triggers pulmonary distress.

Kaletra’s expense further complicates potential use in the areas most devastated by SARS. Kaletra is an expensive protease inhibitor with an annual US cost of around $8,000. Treating SARS patients would not require continual use of the drug as it does for HIV. It is nonetheless unlikely that it would be affordable in areas of Hong Kong and China. The drug’s manufacturer, Abbott Laboratories, would not comment on how this drug might be supplied.

Although the SARS outbreak currently seems to be waning, other outbreaks are likely in the future. Researchers suggest they may even occur every winter, as is a common pattern in respiratory illnesses like the flu. If so, having new treatment options will be essential.

030810
AM030803

Copyright © 2003 by the American Foundation for AIDS Research (amfAR) and first displayed on amfAR's Treatment Directory web site (http://www.amfar.org/gl). They appear on AEGIS with amfAR's permission. Organizations wishing to reprint or redistribute these materials should request authorization from amfAR's Department of Treatment Information Services (212/806-1600).

AEGiS is made possible through unrestricted grants from Boehringer Ingelheim, iMetrikus, Inc., the National Library of Medicine, and donations from users like you. Always watch for outdated information. This article first appeared in 2003. This material is designed to support, not replace, the relationship that exists between you and your doctor.

AEGiS presents published material, reprinted with permission and neither endorses nor opposes any material. All information contained on this website, including information relating to health conditions, products, and treatments, is for informational purposes only. It is often presented in summary or aggregate form. It is not meant to be a substitute for the advice provided by your own physician or other medical professionals. Always discuss treatment options with a doctor who specializes in treating HIV.

Copyright ©1980, 2003. AEGiS. All materials appearing on AEGiS are protected by copyright as a collective work or compilation under U.S. copyright and other laws and are the property of AEGiS, or the party credited as the provider of the content.