Professor's cancer treatment
reaches FDA
By Heather Mangold
City
Editor
Cancer patients could receive more effective and
less harmful treatment in coming years, thanks in large part to the
research of Purdue professor Philip Low and his colleagues.
Low, professor of chemistry, has been researching
a cancer treatment that reduces the harmful effects of chemotherapy
for more than a decade, and now the treatment is in the midst of Federal
Drug Administration clinical testing.
"The problem with current chemotherapy is that
toxic molecules distribute relatively evenly into all cells of the body
and this causes the usual side effects such as where the hair falls
out, bone marrow is suppressed and the immune system is compromised,"
said Low.
Low and his research partners at Endocyte, Inc.,
of the Purdue Research Park, have developed a technique which links
molecules normally used for treating cancer to a homing molecule that
goes preferentially to cancer cells. As a result of this method, cancer
patients would not experience the standard side effects usually seen
in chemotherapy.
This molecule, which was discovered by Low, carries
folic acid into cells. Linking the molecule to already developed cancer
drugs targets cancer cells without harming the patient's "healthy cells"
or the patient's immune system.
"We're basically putting it on a silver bullet
that goes there (to the cancer cells) anyway," said Low. "
Folic acid is a vitamin that cancer cells require
to divide and multiply.
"The cancer cell becomes greedy. We're just exploiting
this greed to the (folic acid) by linking it to a drug that will kill
the cancer cell," said Low. "Normal cells are refractory to these folic
acid drugs, so they won't be affected by the drug."
Ron Ellis, president and chief executive officer
of Endocyte, said, "We're very optimistic, but still a lot of testing
has to be done."
"Probably less than one percent of all drugs that
have been researched make it to clinical testing."
The treatment developed by Low and his partners
at Endocyte is now in its clinical testing stages.
The treatment applies to approximately 40 percent
of all cancer cases including ovarian cancer, uterine cancer, 25 percent
of breast cancer cases, one-third of lung cancer cases, kidney cancer
and brain cancers, said Ellis.
"Right now, there's about 25,000 women in the U.S.
who get ovarian cancer each year and only half survive," he said. "Part
of the reason is because usually it's caught quite late — the cancer
has spread by the time it's been caught. Survival for patients is slim
because there is nothing out there that will treat them."
Ellis said researchers at the company took one
woman who had ovarian cancer and one who did not. They attached the
folic acid to an imaging agent, which showed researchers that the molecule
indeed targeted the cancerous cells in the woman who had cancer.
"We know that the receptor is present; it's not
a question if the cancer has this receptor or not. We know it does,"
he said. "And we know from these human trials in ovarian cancer that
we're able to localize fully targeted drugs in cancer cells."
He said the success of the treatment is a matter
of designing the chemistry to link drugs to the folic acid.
"So far everything looks very encouraging," said
Ellis. "We're very hopeful and optimistic. We can use this technology
to provide better treatment."
He said the reason that the treatment does not
apply to more cancers is that some of them do not have this receptor
to folic acid when it is paired with cancer treating drugs. For instance,
this treatment does not seem to be effective for prostate cancer.
"Prostate cancer tends to be a slow growing cancer
and doesn't need this receptor to absorb this vitamin," he said.
Ellis said that some of the company's work deals
with existing drugs or imaging diagnostic agents and attaching them
to the vitamin, using the vitamin to deliver the drug to cancerous cells.
Other work done by researchers deals with new types of drugs that are
linked to the vitamin.
While researchers are optimistic about the success
of the treatment, Ellis said it won't be too soon before this treatment
is used as standard practice. Clinical testing can involve hundreds
and thousands of patients, and it could be five to seven years before
it's available to sell, said Ellis. He said only about 15 to 20 percent
of all drugs that begin clinical testing in humans are approved by the
FDA.
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