Here's another ASCO summary:
Drs. See New Era in Cancer Research
By Daniel Q. Haney
AP Medical Editor
Wednesday, May 20, 1998; 1:33 a.m. EDT
LOS ANGELES (AP) -- With good reason, cancer docs are the greatest
skeptics in the conservative art of healing. Yet even these cautious souls
stretch for superlatives when describing the changes sweeping over them.
Their big annual meeting, which concluded Tuesday, is ordinarily a rather
gloomy affair. Advances, when they happen at all, inch forward glacially.
Much of what looks promising in test tubes and lab mice turns out to be a
bust when tried on sick people.
''We see this stuff go by, year after year, and nothing works,'' says Dr.
Craig Henderson of the University of California, San Francisco. ''If you
are a practicing doctor, you have to be skeptical. All of a sudden, we are
entering a new era.''
The new era is one of exquisitely targeted therapy. The blunderbuss
approach of chemotherapy -- poisons that kill good cells and bad ones
alike, often with frightful side effects -- will be augmented or even
replaced by chemicals that zero in on malignant cells and leave healthy
ones alone.
''This is the beginning of a large tidal wave,'' says Dr. Laura Hutchins of
the Arkansas Cancer Research Center in Little Rock, Ark.
Traditionally, scientists have tackled cancer by screening thousands of
compounds in the lab, hoping to stumble over one that kills tumors more
efficiently than it kills normal growth. Researchers often test medicines
with little real understanding of how they do whatever they do.
The new approach comes from the opposite direction: Understand what's
wrong inside the cancerous cell, then design a medicine that corrects just
that.
''Throwing bigger bombs at the disease wasn't going to get us a lot
further,'' says Dr. Dennis Slamon of the University of California, Los
Angeles. ''If we show what's broken and target it, we may be able to
develop more effective and less toxic therapies.''
The fundamental difference between cancerous and normal cells lies in the
genes. Genetic errors, accumulated over a lifetime, turn good cells into
bad ones that escape the normal cycle of life and death.
At this week's meeting of the American Society for Clinical Oncology,
Slamon and scientists from the biotech firm Genentech showed how
understanding these genetic miscues can pay off with a unique new
therapy.
Slamon laid the foundation with basic research that showed how some
particularly aggressive forms of breast cancer escape the body's usual
controls: The cancerous cells' genetic mistake makes them overreact to
growth-stimulating hormones. Knowing this, Genentech set about crafting
a solution -- and cloned an antibody, named Herceptin, that blocks the
cancerous cell's ability to receive the growth hormone.
Results released at the meeting show the approach works. While no magic
bullet, it significantly increases the effects of traditional chemotherapy in
terminally ill cancer patients and may be even more impressive when given
earlier in the disease.
Yet perhaps more important even than developing a new cancer drug is
what the process shows about science's potential ability to control cancer
by going to its genetic core.
''This is not like anything we have ever seen before,'' says Dr. Larry
Norton of Memorial Sloan-Kettering Cancer Center in New York City.
''This opens up a whole new chapter in the development of anti-cancer
therapy.''
Most other therapies designed to exploit cancer's unique vulnerabilities are
less far along than Herceptin, which Genentech hopes to have on the
market in the fall.
Another idea is to use drugs to thwart the tumor's ability to connect with
the blood supply of surrounding healthy tissue. In theory, a cancer starved
of blood will not grow and spread.
News reports two weeks ago about two possible drugs to do this, called
angiostatin and endostatin, stirred an enthusiastic buzz about a cancer
cure. But that's highly unlikely, say many at the cancer conference,
considering how complicated and resistant to attack human tumors are.
Among the 1,000 presentations at this week's meeting were dozens aimed
at precisely targeting malignancy. Among the examples:
--Doctors have hooked radioactive iodine onto antibodies designed to
seek cancer cells in people with follicular lymphoma, an incurable form of
blood cancer. Two-thirds of the 32 patients treated at the University of
Michigan are free of all signs of the disease after six to 18 months. It's too
soon to know if the cancer will come back.
--At Baylor College of Medicine in Texas, researchers inserted a herpes
gene into a cold virus, then injected the virus into men's cancerous
prostate glands. The virus infects the cancer cells and carries in the herpes
gene. This allowed the tumor to be killed with a standard herpes drug.
While this can be done safely, it's too soon to know if it will wipe out the
cancer completely
--Scientists at Memorial Sloan-Kettering are among many teams trying to
create vaccines that stimulate the body to kill cancer by recognizing it as
foreign. They are in early human testing of one that triggers a reaction
against cells containing a protein necessary for the production of melanin,
the skin pigment abundant in melanoma skin cancer.
''There is a coming together of focus,'' says Dr. Derek Raghavan of the
University of Southern California. ''Science has actually made some real
progress in the past 12 months.''
Some of the good news involves preventive measures rather than potential
treatments for existing cancers. One study offers the first tentative
evidence that checking blood with the PSA test, which stands for prostate
specific antigen and is now a standard part of checkups for men over 50,
saves lives by spotting prostate cancer early. Another suggests that the
brittle-bone drug raloxifene may reduce the risk of breast cancer by
two-thirds in older women.
Even the most optimistic projections, however, stop short of hinting at any
across-the-board cure. It's more likely, doctors say, that these
approaches will make cancer a more manageable disease, like diabetes or
high blood pressure.
''We won't wake up one day with a cure for cancer,'' Henderson says.
''But if we can make you live 20 years with your disease, and you die of
something else, what's wrong with that?''
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