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Could ViRexx Medical?s ?Linked Recognition?Research Lead to |
A SCIENTISTS 20-YEAR UNFINISHED JOURNEY TO
TREAT HBV MAY OPEN THE DOOR TO A NEW CLASS OF FLEXIBLE VACCINES
While preparing a lecture in biochemistry and virology for his
graduate students at the University of Alberta in the early 1980s,
Dr. Lorne Tyrrell ran across a study just published in the medical
journal, Cell. The research by William Mason and Jesse Summers,
entitled ?Replication of Hepatitis discussed their study of the
hepatitis B virus in infected duck liver.
After studying
their duck model theory, Tyrrell speculated if the hepatitis B virus
(HBV) might be susceptible to antiviral agents, and consulted with a
colleague, who specialized in nucleoside chemistry. Both medical
professors became excited about the possibility of inhibiting the
HBV virus with nucleoside analogues. Thus began the infectious
disease specialists first leg of a journey, which led to the use of
lamivudine as a therapy for chronic HBV infections.
More
than 350 million people across the world, especially in Asia, now
had new hope, some for their lifelong infections contracted
vertically at birth from their mothers. In 2003, the Center for
Disease Control estimated 73,000 Americans were infected with HBV,
and about 5,000 die each year from sickness caused by HBV. It is
reportedly 100 times more contagious than the AIDS virus. Many in
North America, who had been infected with the virus from sexual
transmission or intravenous drug use, were offered a potentially
life-saving therapy.
Licensed in 1998, lamivudine is now
used in 120 countries as a standard therapy for chronic HBV
carriers. The compound is also used in combination with other drugs,
such as protease inhibitors, for HIV therapy. Development rights
were licensed to Glaxo Wellcome in 1990, which is now sold under the
brand name Epivir For his pioneering efforts in developing the
antiviral agent, Dr. Tyrrell was awarded the gold medal by the
Canadian Liver Foundation and the Canadian Association for the Study
of Liver in 2000. In 2005, he won the prestigious EnCana Principal
Award for his development of the first effective oral medication for
Hepatitis B.
HIS UNANSWERED QUESTIONS LAUNCHED A NEW HBV
INVESTIGATION
Despite the awards and recognition, questions
remained for Dr. Tyrrell about the shortcomings of lamivudine. He
was troubled that some viruses would develop resistance to the
compound. ?I was disappointed the sustained viral response was not
complete,Tyrrell told us. In April 2003, the Journal of
Antimicrobial Chemotherapy published a study in Japan showing,
long-term (lamivudine) therapy is associated with increased
emergence of lamivudine-resistant strains of HBV.Researchers
concluded in this study, ?The therapeutic challenge to effectively
treat chronic HBV infection continues.?BR/>
Having screened
lamivudine for use in Hepatitis B at Glaxos research lab at the
University of Alberta, Dr. Tyrrell was able to observe the immune
response of various HBV patients. ?What really got me interested in
doing more work in this area was that we noticed patients, who have
an immune response to the virus and take lamivudine, will have a
better sustained response rate,Tyrrell explained. A patient with
elevated liver transaminases taking lamivudine had a higher
probability of a sustained viral response,Tyrrell said with
excitement in his voice. In a patient with normal liver enzymes, who
gets lamivudine, the virus will go down, but as soon as you stop the
therapy, the virus comes right back up.He told us the sustained
viral response is only about two to three percent. Only about 30
percent remain free of the virus, about one year after patients have
stopped taking lamivudine.
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