September 14, 2009

New Flu Drug Hinders Resistance, Mutation

Researchers reported on Sunday a new experimental flu drug that can stop the swine flu virus from infecting cells and it even seems capable of keeping it from mutating into drug-resistant forms.

After performing tests on mice and in lab dishes, they saw that NexBio Inc.'s drug Fludase can stop the seasonal influenza virus from infecting cells while fighting certain strains of the virus that have become resistant to Roche AG's popular influenza drug Tamiflu, the company said.

"Extensive, prolonged non-clinical influenza studies have not shown the development of any meaningful resistance," the company said in a statement released at the Interscience Conference on Antimicrobial Agents and Chemotherapy in San Francisco.

According to NexBio Inc., tests revealed that Fludase, also known as DAS181, also fights the new H1N1 swine flu virus.

The problem with flu viruses is that they are constantly changing to form defenses against antiviral drugs. For example, last year's seasonal H1N1 virus developed a strong resistance to Tamiflu. Now, two older flu drugs, amantadine and rimantadine, have very little effect against the viruses.

Tamiflu, along with a similar drug GlaxoSmithKline's Relenza, are able to affect a compound in the flu virus called neuraminadase , which is where the "N" comes from in viruses like H1N1.

The difference in Fludase is that it targets human cells that influenza infects, rather than the virus itself. That  should make it less likely to allow the virus to develop a resistance, said company spokesman Dr. David Wurtman.

He said that Fludase affects the sialic acid receptor, which is the molecular doorway used by flu viruses to attach to cells.

"It makes it impossible to spread, so it can't infect neighboring cells," Wurtman said in a telephone interview.

The experiments were conducted by teams at the U.S. Centers for Disease Control and Prevention, University of Hong Kong and Saint Louis University in Missouri, the company said.

"Based on these encouraging data, we are moving forward with our ongoing clinical development of DAS181, and we will continue to work closely with FDA (U.S. Food and Drug Administration), CDC and NIH (the National Institutes of Health) on this clinical program during the current pandemic," said Dr. Ronald Moss of NexBio, who presented the study.

Considering the inclination toward mutation, health experts are predicting that new drugs will soon be necessary to combat the flu.

There are currently several vaccines in development, with BioCryst's peramivir being closest. Peramivir would be made and sold in partnership with Japan's Shionogi.


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