June 20,2001
WASHINGTON (AP) - In research that may offer new hope for treating an
aggressive and lethal cancer, doctors say an injection of a common virus
into the brains of mice caused tumors to shrink without causing other
disease.
Although the study was conducted in laboratory mice, Dr. Peter Forsyth
of the Tom Baker Cancer Centre in Calgary, Alberta, said the virus
injection therapy may be ready for human clinical trials in about six
months.
Forsyth is senior author of a study appearing Wednesday in the Journal
of the National Cancer Institute. The researcher acknowledged he owns
stock in a company that may conduct human clinical trials with the
experimental cancer therapy.
The study extends earlier work, said Forsyth, that proved the concept
of treating cancer using what is called a reovirus. This is a virus that
is common in the lungs and gut of humans, but which is thought to be
harmless except to cancer cells.
``Normal cells have a block to infection and death from reovirus,''
Forsyth said. ``The virus can get into the normal cell but cannot infect
it further.''
But the reovirus can invade cancer cells and go wild, he said.
``The cancer cell become a bloated bag of viral particles,'' said
Forsyth. ``It explodes, and the viruses are released to go on and infect
and kill other cancer cells.''
In the study, Forsyth and his colleagues implanted laboratory cells of
glioblastoma, a highly aggressive form of brain cancer, into the brains of
two dozen mice. Once the cancer cells were established and growing, half
of the mice received injections of live reovirus and half got injections
dead reovirus.
Forsyth said that the mice with the inactive virus died within a short
time from their tumors, while at 90 days eight of the 12 mice that
received live virus were still living.
``Animals treated with live virus appeared to be healthy and gained
weight,'' the study said.
In an editorial in the Journal, Dr. Matthias Gromeier of Duke
University said the study ``produced very encouraging results.''
In an interview, however, Gromeier said the new study does little to
advance work first reported by Forsyth and others in 1998.
Gromeier also noted that although the reovirus does not produce any
recognized disease in humans, there are many unknowns about the effect the
virus might have if it were injected into the brain of a human.
``There are a number of aspects of the proposed strategies with
reoviruses that are in the dark,'' said Gromeier, a scientist who is
researching the use of another type of virus in the treatment of cancer.
Copyright 2001 The Associated Press. All rights reserved.
