Background:  Influenza

 Influenza (flu) A & B are members of the virus family Orthomyxoviridae and are distinguished by the proteins that make up their viral coatings.

Flu A subtypes include the 2009 H1N1 (A/H1N1 or swine flu) and H5N1 (avian flu). According to the Centers for Disease Control & Prevention (CDC), on average each year in the United States:

  • 5% to 20% of the population will suffer from an Influenza infection
  • More than 200,000 people are hospitalized due to complications of flu
  • About 36,000 people die from flu-related causes

 Vaccination against influenza is possible but, as evidenced in the 2009 A/H1N1 pandemic, determination of the correct vaccine can sometimes be problematic and mass production of a new vaccine can be very slow. We were fortunate that the rapidly transmitted A/H1N1 strain did not have a high mortality rate. The avian flu strain (H5N1) has demonstrated lethality in 65% of those infected but is not as readily transmissible as H1N1 between humans. However, since the two strains have been demonstrated in the same animals and in the same tissues, the possibility of viral reassortment to produce a highly transmissible and highly pathogenic strain is a major concern to the health of the global population. In 1918 the Spanish flu infected and killed many otherwise healthy individuals and may have contributed to as many as 50million deaths worldwide.

Approved therapeutics for treatment of Influenza infections in individuals include Zanamivir (Relenza; GSK), Oseltamivir (Tamiflu; Roche)1, and the adamantanes – e.g. Amantadine and Rimantadine. However, amino acid substitutions within the transmembrane region of the influenza M2 protein confer resistance to rimantidine and other members of the adamantane drug class. In fact, the CDC has suggested that 100% of seasonal (H3N2) and 2009 pandemic flu (H1N1) samples tested have shown resistance to the adamantanes and these are no longer recommended for treatment of flu (CDC 20062).

Viral resistance to Tamiflu has also been observed and estimates suggest that 99.6% of the H1N1 viral strains showed resistance to the drug – especially in children with flu [WHO 20103]. Tamiflu resistance was particularly evident in immunocompromised patients.

As with Tamiflu, Relenza also targets the viral Neuraminidase, but must be delivered through oral inhalation - requiring distribution of a metered inhaler device along with the drug.

With such issues around the existing therapeutics for treatment of influenza infection, the tremendous market opportunity (representing several $$billion per year), together with the continuing emergence of new viral strains around the world, there is ample room for new small molecule therapeutics for treating influenza infections.

In fact, a new therapeutic with a novel mechanism of action that is orally available and shows broad anti-influenza activity with an exceptional safety profile has the potential to garner a significant share of the therapeutic market for influenza in a short period of time.

AnaViRx is committed to bringing such novel therapeutic options to the marketplace.

 

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