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From: "Peter Christiansen" <>
Date: Sat, 9 Mar 2002 12:33:45 -0600
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Cuban cancer drug shows promise
Biotech agent targets head and neck tumors molecular roots
By Mary Murray
NBC NEWS
HAVANA, March 8 Cuban researchers this week reported early, but notable
success with a biotech drug that attacks advanced cancer of the head and neck
regions. In preliminary trials, the novel agent, called Theracim h-R3, enhanced
conventional radiation therapy to radically shrink and even completely eradicate
tumors.
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RESEARCHERS at Havana s Center of Molecular Immunology administered
radiation plus Theracim h-R3 to 70 patients whose head and neck cancers
had failed to respond to conventional therapy.
Tumors completely disappeared in 60 percent. In contrast, only 30 percent
to 40 percent of advanced patients given radiation alone in Cuba would
expect to see their tumors eliminated, said the Center s Normando
Iznaga-Escobar.
To date, patients given the one-two punch from radiation and Theracim
h-R3 have remained tumor-free for as many as 28 months, he added.
Additionally, another 20 percent of patients saw their tumors shrink by
at least half, said Dr. Rolando Perez, head of the Center s research
and development division.
Few therapies have demonstrated such an overall response rate and
survival benefit of this disease, said study author Dr. Tania
Crombet, also of the Center.
To develop Theracim h-R3, the researchers took advantage of the fact that
the growth of some tumors is fueled by substances known as epidermal
growth factors. And, on their outside shell, some tumors have chemical
docking stations known as receptors to these growth factors.
Scientists figured out that when they stimulate these receptors, tumors
grow faster than ever. So, they reasoned that if they developed an
antibody that seeks out, attaches to and gums up these receptors, cancer
growth will be slowed, even halted.
Which is just what happened, according to Iznaga-Escobar.
HER-1 TARGETED
Specifically, Theracim h-R3 inhibits an epidermal growth factor receptor
known as HER-1. Up to 90 percent of patients with head and neck cancer
have too much HER-1, he said, causing cancer cells to reproduce out of
control and spread through the body.
Dr. Roy Herbst, a molecular oncologist at M.D. Anderson Cancer Center in
Houston, said that HER-1 is a good target for an anti-cancer
drug. By blocking HER-1, which has been implicated in head and neck,
colon, pancreatic and other tumors, a drug should theoretically slow
down, even reverse, cancer s course.
But large clinical trials comparing the drug to placebo are needed to
prove that, Herbst said. In the United States, where radiation therapy is
more sophisticated than in Cuba, the tumor-eradication rate can reach 60
percent as high as seen in the Cuban trial of radiation plus
Theracim h-R3, he added.
And other HER-1 blockers, such as IMC-C225, are further along down this
road than Theracim h-R3.
This is interesting, but for now it s just another of many such
molecules being tested, Herbst said. We look forward to seeing
further study.
A head-to-head trial comparing radiation plus placebo to radiation plus
Theracim h-R3 is already underway by the Center, in partnership with
Ontario-based YM BioSciences Inc., said Iznaga-Escobar.
He acknowledged that IMC-C225 is further along in development. But, he
said, Theracim h-R5 appears to be less toxic. The most common adverse
effects include mild fever, chills and nausea in some 45 percent of
patients.
In contrast, IMC-C225 has been linked to more severe side effects,
including skin rash, Iznaga-Escobar said.
FAST TRACK
According to Perez, Cuba s National Regulatory Authority the U.S.
Food and Drug Administration s equivalent has placed Theracim h-R3
on fast-track approval. In Cuba, unlike in the United States, this allows
the drug to be sold during the final phase of testing now underway.
That makes Theracim h-R3 one of only a handful of so-called humanized
monoclonal antibodies available around the world, he said. Others include
Panorex, approved in Germany in 1994 for patients with colon cancer, and
Herceptin, approved in the United States for treating breast cancer.
If the final phase of testing goes as expected, with the same good
results, Perez said he believes Canada will approve Theracim h-R3 by
early next year.
HEAD AND NECK CANCER
In 2001, close to half a million new cases of head and neck cancer were
detected around the world. During that same period, 244,413 people died
from the disease.
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Cuba s National Cancer Institute blames lifestyle, particularly alcohol
abuse and tobacco consumption, as the leading causes.
Cuba has the dubious distinction of having one of the highest smoking
rates in the world. We are in the midst of a very important
anti-smoking campaign. If we manage to reduce smoking over the next 20
years, we could cut all cancer rates by one-third, said CNCI s
Dr. Miguel Azcuy.
Portia Siegelbaum in Havana contributed to this report.
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