Microsoft word - influenza antiviral.doc

The Influenza Antiviral Market:
The Reality of Resistance
A Complimentary Market Research Study as included in:
The Antiviral Pipeline: HIV, HCV and Infuenza Report www.InsightPharmaReports.com
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Insight Pharma Reports, a division of Cambridge Healthtech Institute While the neuraminidase inhibitors oseltamivir (TAMIFLU, Roche Laboratories [Nutley, NJ]) andzanamivir (RELENZA, GlaxoSmithKline [Research Triangle Park, NC]) are currently the mosteffective drugs against influenza, they may lose their potency in the future if viral resistance toneuraminidase inhibitors continues to spread. The previously circulating “seasonal flu” H1N1 virus(i.e., not the currently circulating 2009 H1N1 virus) was highly resistant to oseltamivir. In somecountries, 100% of the 2008–2009 seasonal H1N1 samples tested were resistant to oseltamivir,representing a dramatic increase from previous years. During the 2006–2007 season, less than1% of all H1N1 cases tested in the United States showed signs of resistance to oseltamivir.
Resistant strains of the currently circulating human influenza strain, 2009 H1N1, have beenisolated. CDC antiviral resistance testing results indicate that almost all (98.7%) of the 2009H1N1 cases that occurred during the 2009–2010 flu season (i.e., since September 1, 2009) andwere tested were susceptible to oseltamivir. All of them (100%) were susceptible to zanamivir.
However, a handful (1.3%) of the 2009–2010 flu season 2009 H1N1 samples collecteddemonstrated resistance to oseltamivir. When it was first detected in May 2009, none of the 2009H1N1 samples showed signs of oseltamivir resistance. Public health experts are alarmed not onlyby the slowly increasing resistance rates among 2009 H1N1 viral samples but also the risk of the2009 H1N1 and H5N1 viruses recombining into an even more resistant strain.
Resistance has also been detected in the avian H5N1 virus (which so far is not capable ofhuman-to-human transmission).31 Either way, whether dealing with seasonal influenza (e.g., theseasonal H1N1 virus) or novel pandemic influenza viruses (e.g., 2009 H1N1), neuraminidaseinhibitor resistance is a potentially very serious problem. Neuraminidase inhibitors not onlyprovide considerable protection against serious complications from influenza infection, reducingthe risk of death among hospitalized adults with laboratory-confirmed infections,they also serve a prophylactic role. For example, for the 2009–2010 season, when H1N1influenza was considered a national public health emergency (i.e., until June 23, 2010), the CDCrecommended antiviral therapy as a prophylaxis for persons who had been in close contact withsomebody with suspected or confirmed 2009 H1N1 influenza AND who either were at high riskfor complications, worked in healthcare or emergency medicine, or were pregnant. The CDC alsoprovides detailed guidelines on its Web site for the administration of prophylactic influenzaantivirals in the event of an outbreak in an institutional setting (seewww.cdc.gov/h1n1flu/recommendations.htm) Resistance is not the only problem with the currently available influenza antivirals. Otherconcerns include the need for a reliable form that can be administered to seriously ill patients,including people who can’t take oral medicines; the need to determine safety and efficacy in high-risk populations, such as in hospitalized or immunocompromised patients and infants youngerthan one year old; the need to determine under which circumstances and combinationscombination therapy is safe and effective; and the need for more simplified dosing. Of these,and as was made clear in the August 2009 Report to the President on U.S. Preparations for2009-H1N1 Influenza,32 prepared by the President’s Council of Advisors on Science andTechnology, the need to develop and expedite licensure of intravenous formulations of antiviralsfor use in seriously ill patients is the most important.
The three lead influenza antiviral compounds currently in development show the potential to meetthese other needs: 1. BioCryst’s investigational IV-administered peramivir, which was granted Emergency Use Authorization (EUA) in October 2009, is intended for use in hospitalized patients with seriousillness.
2. Daiichi Sankyo and Biota Holdings’ neuraminidase inhibitor CS- 8958 has long-lasting effects that make it suitable for once-daily and, in the case of prophylaxis, once-weekly dosing.
Toyama Chemical’s potential first-in-class polymerase inhibitor T-705 has demonstratedrobust activity against a range of influenza viruses.

Source: http://ckt.thebiotech.net/Influenza%20Antiviral.pdf