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ImmuneRegen BioSciences' Viprovex(R) Demonstrates Further Evidence for Effectiveness Against Influenza Virus, Including Avian Flu

Posted on: Monday, 12 November 2007, 09:00 CST

Today ImmuneRegen announced additional findings from small animal studies of its lead clinical candidate, Viprovex, for treatment of infectious diseases. Ongoing studies in an accepted model for human respiratory virus infection, the Cotton Rat (Sigmodon hispidus), continue to show the ability of Viprovex to decrease the symptoms and aftereffects of certain influenza virus strains.

In previous studies, Viprovex has demonstrated positive results including decreased weight loss and hypothermia exhibited by influenza-infected cotton rats. Reduced concentration of influenza virus in the respiratory system was also observed both one and four days after infection, which may indicate a lowered likelihood of viral transmission. In addition, animals treated with Viprovex demonstrated less pulmonary inflammation which had been previously demonstrated on viral exposure and which persisted even after Tamiflu administration.

In addition to this data from rats, earlier studies of influenza infected mice also showed fewer virus particles in lungs, as visible by electron microscopy. Preliminary data from studies in a third species, the ferret, using highly pathogenic H5N1 influenza A virus (commonly known as 'avian flu') suggests similar anti-viral effects in this well-accepted small animal model of influenza infection. This anti-viral effect was thus seen consistently in three small animal species that are models for influenza virus infection in man.

The new studies announced today also revealed additional details of the positive interaction of Viprovex with Roche's Tamiflu®, a neuraminidase inhibitor that is used to combat influenza strains including bird flu. In previous studies, Viprovex demonstrated the ability to reduce the impact of influenza virus administration in cotton rats, which have included pulmonary inflammation and, in some studies, elevated mortality, which was highest in Tamiflu-treated, influenza-infected animals.

Linkage of known neuropsychiatric adverse effects of Tamiflu in man to observed pulmonary inflammation and Tamiflu-associated deaths in small animal models is speculative, but with the widespread distribution and stockpiling of Tamiflu around the globe, understanding of potential interactions is of paramount importance.

A recent publication (Morimoto et al., 2007) sheds some light on the potential neuropsychiatric adverse events previously reported for Tamiflu, especially in children (see http://www.fda.gov/cder/drug/infopage/tamiflu/QA20051117.htm, an FDA announcement accessed November 5, 2007). Morimoto et al. report that Oseltamivir phosphate (the administered pro-drug), but not the active anti-influenza metabolite (Oseltamivir carboxylate, or Ro 64-0802), can accumulate in brain when the multiple drug resistance protein p-glycoprotein is inhibited or absent (doi:10.1124/dmd.107.017699). Human brain also contains p-gp oriented to pump drugs out of the central nervous system and with similar localization as in rat brain (Bendayan et al., 2006).

As pro-inflammatory cytokines have been reportedly associated with a decreased expression (of mRNA and protein) and activity of p-glycoprotein (Fernandez, 2004), it is possible that an inflammatory condition could result in cytokine levels that decrease expression and/or activity of p-glycoprotein, and thereby result in accumulation in brain of the Oseltamivir pro-drug. The anti-inflammatory activity of Viprovex (as reported earlier in lungs of infected animals and as published in early studies of Viprovex in models of inhaled toxicants) might, in contrast, modify cytokine levels so as to ensure effective p-glycoprotein expression and activity, resulting in a lowering of Oseltamivir levels in the CNS.

The observed responses to Tamiflu in small animal studies may have significant ramifications in the event of widespread use of the drug to prevent or treat pandemic influenza. Tamiflu is essential to global prophylactic and therapeutic pandemic influenza planning, as well as plays a significant role in treating seasonal influenza. Even while U.S. Department of Health and Human Services stockpiles of Tamiflu provide a domestic safety net against a potential Avian Flu pandemic, the FDA has announced they will be looking into questions about Tamiflu's neuropsychiatric safety in a November 2007 meeting. In this context, the ability of Viprovex to reduce inflammation and mortality in Tamiflu-treated infected animals could reflect a beneficial role for Viprovex. ImmuneRegen is performing additional studies to further explore Viprovex's effectiveness. The company hopes to begin working closely on these initiatives with pharmaceutical firms active in the anti-influenza marketplace.

About Radilex(TM) and Viprovex®

Radilex(TM) is the trade name used in referring to formulations of Homspera(TM) for potential indications for treatment of exposure to ionizing radiation. Viprovex® is the trade name used in referring to formulations of Homspera(TM) for potential indications for treatment of viral and bacterial infections. Homspera(TM) is a generic name used by the Company to describe the synthetic peptide Sar9, Met (O2)11-Substance P. Sar9, Met (O2)11-Substance P is an analog of the naturally occurring human neuropeptide Substance P, which can be found throughout the body, including in the airways of humans and many other species. All of the Company's research and development efforts are early, pre-clinical stage and Homspera(TM), as Viprovex® and Radilex(TM), has only undergone exploratory studies to evaluate its biological activity in small animals.

About ImmuneRegen BioSciences, Inc.

IR BioSciences Holdings, Inc., through its wholly owned subsidiary ImmuneRegen BioSciences, Inc., is a development stage biotechnology company focused on the research and development of Homspera(TM) and its derivatives Radilex(TM) and Viprovex®, which are designed to be used as countermeasures for multiple homeland security bioterrorism threats. Homspera(TM) is derived from Substance P, a naturally occurring peptide immunomodulator and homeostatic compound with the dual effect of improving pulmonary function and the stimulation of the human immune system. For more information, please visit the company's website at http://www.immuneregen.com.

Forward-Looking Statements

Statements about the Company's future expectations, including statements about the potential for the Company's drug candidates, science and technology, and all other statements in this press release other than historical facts, are "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, Section 21E of the Securities Exchange Act of 1934, and as that term is defined in the Private Securities Litigation Reform Act of 1995. The Company intends that such forward-looking statements be subject to the safe harbors created thereby. These future events may not occur as and when expected, if at all, and, together with the Company's business, are subject to various risks and uncertainties. The Company's actual results could differ materially from expected results as a result of a number of factors, including the fact that preliminary results involved only a small number of test mice, the subsequent investigations were limited in scope, the uncertainties inherent in research and development collaborations, pre-clinical and clinical trials and product development programs, (including, but not limited to the fact that future results or research and development efforts may prove less encouraging than current results or cause side effects not observed in current pre-clinical trials) the evaluation of potential opportunities, the level of corporate expenditures and monies available for further studies, capital market conditions, and others set forth in the Company's periodic report on Form 10-QSB for the three months ended June 30, 2007 and on Form 10-KSB for the twelve months ended December 31, 2006 as filed with the Securities and Exchange Commission. There are no guarantees that any of the Company's proposed products will prove to be commercially successful. The Company undertakes no duty to update forward-looking statements.

Source: Business Wire

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