This is important because it can
surely be used to successfully detect early stage cancer with serious success. This is something that has not been possible
in any meaningful way in the past. So
far though, the method could possibly be available once because it would
presently trigger an immune response.
On the other hand, we believe
that cancer takes years to show up although there is also good reason to
question that.
The method is designed to allow
cancer sells to be lit up, allowing easy discovery. Assuming that this can also be used as a drug
delivery system we have another plausible effective tool against cancer.
Genetically Altered Virus Detects Cancers Early
Released: 5/9/2011 7:00 AM EDT
Embargo expired: 5/11/2011 5:00 PM EDT
Newswise — CINCINNATI – Scientists have used a genetically
re-engineered herpes virus that selectively hunts down and infects cancerous
tumors and then delivers genetic material that prompts cancers to secrete a
biomarker and reveal their presence.
According to a study appearing May 11 in PLoS (Public Library of
Science) ONE, the novel technology has the potential to vastly improve cancer
diagnosis by allowing the disease to be caught at much earlier stages and to
monitor the effectiveness of therapy.
Researchers at Cincinnati Children’s Hospital Medical Center
“Our study represents a proof-of-principle in mice, and there is
certainly room for further refinement. If ultimately validated in human trials,
it could have implications for people with known cancer risk or who have a
history of cancer and high risk of recurrence,’’ said Timothy Cripe, M.D.,
Ph.D., senior investigator on the study and a physician and researcher in the
Division of Oncology at Cincinnati Children’s.
“Early cancer detection is vital to improve cure rates because cancer
stage predicts prognosis, but biomarkers are known for only a few cancer types.
We were able to use a reprogrammed herpes virus administered intravenously to
deliver genetic information that induces a known blood biomarker for cancer to
be secreted by cancer cells,” explained Dr. Cripe, who collaborated on the
study with first author, Andrew Browne, Ph.D., a fourth-year medical student at
the University of Cincinnati (UC) College of Medicine and a recent graduate
from UC’s Department of Electrical and Computer Engineering.
The researchers engineered a herpes simplex virus mutant they called
rQ-M38G, reprogramming its genetic makeup so it bypasses healthy tissues and
instead targets rapidly dividing cancer cells for infection. They also genetically
armed the virus so it prompts cancer cells to secrete Gaussia luciferase
(GLuc).
GLuc is a luminescent, easily detectable protein the researchers
used as a universal blood biomarker for cancer cells infected by rQ-M38G.
Because rQ-M38G/GLuc might also help shrink cancer, it is part of a new class
of agents dubbed “theragnostics” that can simultaneously be used for diagnosis
and therapy, Dr. Cripe said.
Initially the researchers tested rQ-M38G on laboratory cell cultures of
healthy dormant human skin cells and on rapidly dividing cancer cells. Virus
replication and biomarker production were very low in the dormant normal cells.
In contrast, virus replication and biomarker production were much higher in
tumor cell lines of malignant peripheral nerve sheath tumors, osteosarcoma
(bone cancer), rhabdomyosarcoma (muscle cancer) and Ewing
sarcoma.
Researchers then tested the virus’s detection capabilities in mouse
models of these same cancers by injecting rQ-M38G into their tail veins, and
for comparison into the tail veins of healthy control mice. Non-tumor bearing
mice showed background signals for the virus without significant replications
or biomarker production. More than 90 percent of the tumor bearing mice showed
significant virus replication and biomarker production.
The technology even worked in some mice with only microscopic amounts
of cancer in their kidneys, researchers report. If it were to work as well in
humans, the scientists estimate that hidden tumors less than half-inch in
diameter might be detectable. Because of the anticipated immune response
against the virus and the GLuc protein in humans, further refinements of the
technology will likely be needed to be able to use it more than once.
The study is one more example of the expanding research into using
reprogrammed HSV as novel methods to treat or diagnose cancer, especially as
medicine reaches the limits of modern chemotherapies. Dr. Cripe said this
creates an urgent need for new strategies against stubborn metastatic disease.
Less than 30 percent of patients with metastatic cancer survive beyond five
years, despite the aggressive use of modern combination therapies that include
chemotherapy.
Also collaborating on the current study were Jennifer Leddon, Mark
Currier, Jon Williams, Jason Frischer, and Margaret Collins all of Cincinnati
Children’s.
Funding support for the study came from The Cancer Free Kids Pediatric
Cancer Research Alliance
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