NEWS SCAN: FDA approves raxibacumab for anthrax, influenza B with reduced susceptibility, H5N1 drift in Egypt

Dec 14, 2012

FDA approves raxibacumab for inhalational anthrax
The US Food and Drug Administration (FDA) today approved GlaxoSmithKline's injected drug raxibacumab to treat inhalational anthrax, a form of the disease caused by the bacterium Bacillus anthracis. The FDA also approved the drug, a monoclonal antibody, to prevent inhalational anthrax when alternative therapies are not available or appropriate. "In addition to antibiotics, raxibacumab will be a useful treatment to have available should an anthrax bioterrorism event occur," Edward Cox, MD, MPH, director of the Office of Antimicrobial Products at the FDA's Center for Drug Evaluation and Research, said in an FDA release. "Although antibiotics are approved to prevent and treat anthrax infection, raxibacumab is the first approved agent that acts by neutralizing the toxins produced by B anthracis." The FDA had fast-tracked the drug because of its potential against anthrax, a potential bioterror threat. Last month an FDA committee had voted for approval of the drug. Its effectiveness was shown in one study in monkeys and three studies in rabbits, according to the release. A safety study in 326 healthy human volunteers showed side effects that included rash, extremity pain, itching, and drowsiness.
Dec 14 FDA press release
Nov 6 CIDRAP News scan on committee approval

Carolinas found influenza B with reduced Tamiflu susceptibility in 2010-11
During the 2010-11 flu season both North Carolina and South Carolina recorded elevated levels of an uncommon influenza B strain that has reduced susceptibility to oseltamivir (Tamiflu), scientists from the US Centers for Disease Control and Prevention (CDC) and both states said in a report yesterday in the Journal of Infectious Diseases. Of the B viruses submitted from the two states to the CDC, 45 (22%) of 209 from North Carolina and 8 (10%) of 82 from South Carolina had the I221V neuraminidase substitution, which confers lowered susceptibility, but not resistance, to oseltamivir. In comparison, 3 (0.3%) of 881 B viruses from 45 other states had the substitution. The authors said the I221V viruses did not affect illness severity. When the North Carolina Department of Health and Human Services announced detection of these viruses in March 2011, it assured physicians and their patients that antiviral treatment still worked against the viruses, which showed no reduced susceptibility to the other common neuraminidase inhibitor, zanamivir (Relenza).
Dec 13 J Infect Dis abstract
Mar 29, 2011, CIDRAP News story on North Carolina announcement

5-year analysis shows antigenic drift in H5N1 viruses in Egypt
An analysis of H5N1 avian flu strains isolated from Egyptian patients from 2007 through 2011 found little evidence of reassortment but substantial antigenic drift, according to a report yesterday in Emerging Infectious Diseases. US and Egyptian investigators sequenced the complete genomes of 59 H5N1 virus isolates and 13 hemagglutinin (HA) genes sequenced directly from clinical specimens of 72 patients. "We found minimal evidence of reassortment and no exotic introductions," they wrote. "The hemagglutinin genes of the viruses from 2011 formed a monophyletic group within clade 2.2.1 that also included human viruses from 2009 and 2010 and contemporary viruses from poultry; this finding is consistent with zoonotic transmission." While they found little evidence of reassortment, they observed "substantial antigenic drift" when they performed HA inhibition tests using ferret antisera and compared results against a panel of H5N1 viruses. Egypt confirmed 158 human H5N1 cases during the study period.
Dec 13 Emerg Infect Dis report

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