From: Greg Burch (gregburch@gregburch.net)
Date: Thu May 08 2003 - 19:04:12 MDT
This seems Really Important -- is it?
http://www.chron.com/cs/CDA/ssistory.mpl/metropolitan/1899204
May 7, 2003, 9:36AM
Cold virus outsmarts, destroys brain tumors
Genetically engineered cells target only cancers
M.D. Anderson plans clinical trials for next year
By TODD ACKERMAN
Copyright 2003 Houston Chronicle Medical Writer
RESOURCES
. Graphic: Virus kills brain tumors
Local scientists have turned a cold virus into a kind of "smart bomb"
that may be able to destroy the deadliest form of brain cancer.
In experiments with mice, University of Texas M.D. Anderson Cancer
Center researchers are reporting that a genetically engineered version
of the common cold infected and killed malignant glioma cells that
resist other therapy. The virus doesn't harm normal tissue.
"Viral therapy like this may be just what we need to treat a complex
disease like cancer," said Dr. Frederick Lang, a professor of
neurosurgery and primary investigator of the study. "Cancer can be
devious the way it does everything possible to avoid destruction, but
viruses are equally tricky and may be able to outsmart brain tumors."
In today's issue of the Journal of the National Cancer Institute, M.D.
Anderson researchers said the therapy produced a response on glioma not
previously seen with any other treatment. Clinical trials with people
are expected to begin late next year.
Roughly 17,000 new cases of brain tumors are diagnosed in the United
States every year and half are gliomas, a primary type which arises from
the brain itself rather than metastasizing from another location.
Surgery, radiation therapy, steroids and chemotherapy can prolong
survival, but most everyone dies within a year.
The virus is designed in such a way that to reproduce itself, it can
only replicate in cancer cells, not healthy tissue. While reproducing,
it kills cancer cells, and when no more are left to infect, the virus
simply dies.
The idea of using viruses to kill cancer cells has been around since the
1950s, but it is only in recent years that it is moving toward
application. Therapeutic viruses for lung cancer and head and neck
cancer are in clinical trials, said Howard Fine, director of the brain
tumor program at the National Cancer Institute.
The NCI is providing $1 million to produce the drug-grade version of the
therapy in its laboratories. It is scheduled to be finished in time to
start enrolling patients in a study in the winter of 2004.
But Fine warned against expecting too much from the therapy. He called
it "a promising approach that is one of many good ideas out there," but
said success in animal models is a long way from success in human
patients. He said it is unclear whether the virus will replicate as well
in humans, where glioma cells are surrounded by normal cells; in mice,
glioma cells cluster together.
But the results in the mice were extraordinary. The virus cured 60
percent of the glioma tumors implanted in mice brains whereas mice given
a placebo died after less than three weeks. (A precursor of the virus
cured 15 percent of the tumors.)
The mice that survived treatment with the experimental virus were killed
for examination. Researchers found only empty cavities and scar tissue
where the tumors once were.
"This therapy needs more study, but it has a lot of potential," said Dr.
Juan Fueyo, a professor in M.D. Anderson's department of neuro-oncology,
the study's lead author and the developer of the genetically engineered
adenovirus. "We've never had this kind of result with any kind of
treatment on glioma -- in humans or animals."
The virus is injected directly into the brain tumor surgically, through
a small hole. Lang expressed hope the therapy might work even better in
humans because delivery would be more precise.
Researchers are studying human adenoviruses for a wide range of medical
uses, from cancer therapy to gene therapy, because they are so good at
infecting human cells. One question is how the immune system will
respond -- will it overreact and cause illness or kill the virus, or
will it be boosted to kill the cancer or other pathogen.
But Lang said he's optimistic the treatment will accomplish its goal
before the immune system goes after it.
The research team also included scientists from the University of
Alabama at Birmingham and the Institut Catala d'Oncologia in Barcelona,
Spain.
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