LONDON (November 17, 2005) – A cross-Canada
scientific collaboration has successfully tested a
potent new cancer-fighting virus that eliminates
malignant brain tumors and prolongs survival in
mice with a single injection.
The scientists – from Calgary and London,
Ontario – have shown for the first time that
myxoma virus, a poxvirus, will kill human brain
tumors in mice and prolong the animals’ survival.
Their findings are published this month in the
journal of Cancer Research.
“We’re extremely encouraged by these results
and the apparent cure seen in the mice treated
with the active virus compared to untreated mice
or those injected with inactivated virus,” says
virologist Grant McFadden, a scientist at Robarts
Research Institute in London and Canada
Research Chair in Molecular Virology. His research
on poxviruses over the past two decades has shed
significant light on how viruses disarm their hosts’
immune systems – and their potency as anti-
cancer and anti-inflammatory agents.
For the brain tumor experiments, McFadden
teamed up with Dr. Peter Forsyth of the University
of Calgary, a professor in the departments of
oncology, and biochemistry & molecular biology,
who has developed a mouse model with human
gliomas, a malignant form of brain tumor that
strikes 2500 people each year. Over the past 2
years, their laboratories have tested the virus
against experimental models of human malignant
tumors, both in cell culture and in living animals.
Injecting the tumor with the virus was not only well-
tolerated – with only minimal inflammation at the
site of the inoculation – but 92 per cent of the 13
mice treated were alive and apparently “cured”
when the experiment was finished (after more than
130 days).
“Those animals continued to show a selective
and long-lived myxoma virus infection in the
tumors themselves but that infection did not
spread and harm the animal,” says Dr. Forsyth,
director, Clark H. Smith Integrative Brain Tumour
Research Centre. “This and other factors suggest
that myxoma virus warrants further investigation as
a potential treatment for malignant brain tumors
in people.”
The University of Ottawa also played a major
role: Dr. John Bell initiated the Canadian
Oncolytic Virus Consortium, a program funded by
The Terry Fox Foundation, to study various viruses
with the potential to treat cancer. In 2004, Dr. Bell
brought together the teams from London and
Calgary to initiate the study reported in Cancer
Research.
McFadden and Forsyth are now planning to
test the virus as a treatment for a deadly
melanoma that is known to spread to the lung.
They will be able to tag the virus with a
fluorescent protein and track its progress in mice as
it attacks the metastasized tumor cells.
“Oncolytic viruses are a particularly exciting
weapon emerging in the fight against cancer,”
McFadden adds. “There is a lot more preclinical
work ahead but the next step is to learn how best
to harness their potency and their potential.”
Dr. Forsyth’s work is supported by the Canadian
Cancer Society, Canadian Institutes of Health
Research, Alberta Cancer Foundation (ACF), Kid’s
Cancer Care Foundation and the Clark H. Smith
Integrative Brain Tumor Research Center.. Dr.
McFadden’s research is supported by the
Canadian Cancer Society, and Canadian Institutes
of Health Research.
For more information contact:
Linda Quattrin
Robarts Research Institute
(519) 663-3021
lquattrin@robarts.ca
Karen Thomas
University of Calgary Faculty of Medicine
(403) 220-2431
thomask@ucalgary.ca