WASHINGTON, July 31 (Reuters) - A virus that has
been genetically engineered to home in on and destroy cancer cells has shown
strong and lasting effects against tumors in patients when combined with
standard chemotherapy, researchers said on Monday.
They said 25 out of
30 patients with head and neck cancer saw their tumors shrink after they were
treated with Onyx Pharmaceuticals Inc.'s
<<A HREF="aol://4785:ONXX">ONXX.O</A>> ONYX-015 along with
chemotherapy.
Eight tumors disappeared, Dr. Fadlo Khuri and colleagues at
M.D. Anderson Cancer Center in Houston, working with teams in Britain, wrote
in the journal Nature Medicine.
"ONYX-015 may be able to sensitize
infected and uninfected cells to killing by chemotherapy," they
wrote.
"It is very encouraging because this is the first time there has
been a Phase II trial -- a trial with more than just a few patients in it --
where the tumors have gone away in a significant number and they haven't come
back," gene therapy pioneer Dr. William French Anderson of the University
of Southern California said in a telephone interview.
"There are lots
of Phase I trials where you get tumors to go away but they come
back."
Phase I trials are only to find out if a treatment is safe and
involve very few people. Phase II trials involve more people but volunteers
are often critically ill because safety is still being assessed. Phase III
trials involve a larger number of people and are the final phase aimed
at determining whether a treatment or drug actually works.
Every year,
500,000 people worldwide are diagnosed with cancer of the head and neck, and
about 30 percent of them die. Such cancers, heavily associated with the use
of alcohol and tobacco, are treated at first with surgery, radiation therapy
or both.
But tumors come back in about a third of patients. When this
happens, the outlook is grim.
Doctors have tried chemotherapy, but it
makes patients ill and does not seem to help them live any
longer.
Gene therapy is a possible new approach.
Anywhere between
45 and 70 percent of head and neck tumor cells have mutations in a gene known
as p53, which, when normal, helps repair cancer-causing
damage.
ONYX-015 is an adenovirus, a relative of common cold viruses,
that has been genetically engineered to attack cells that lack normal
p53.
This makes it technically a gene therapy drug, although unlike other
gene therapy approaches ONYX-015 does not repair or replace a faulty
gene, Anderson said.
