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New Cancer Treatment May Stop Blood vessel growth

Health
Bull's Eye
Zina Moukheiber,
12.22.03
"A much-touted cancer treatment could end up fighting
something completely different: the dreaded macular degeneration"
Could this treatment give hope to FEVR
patients we ask? "Macular degeneration is like cancer. You have very
aggressive, abnormally growing vessels that are hard to turn off" This is
also true in FEVR except the extra out of control cancer like blood vessels are
in the peripheral (outside ) portions of the vision instead of the central
vision.
Here is an article posted on Forbes.com
Health
Bull's Eye
Zina Moukheiber,
12.22.03
A much-touted cancer treatment could end up fighting something
completely different: the dreaded macular degeneration
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By the Numbers |
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| Age 40 seems to be
when things go downhill for Americans' vision, at least according to
government statistics. |
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30.5 million
People 40 and over who are nearsighted. |
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20.4 million
People with cataracts. |
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11.9 million
People who are farsighted. |
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8.7 million
People with age-related macular degeneration. |
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3.4 million
People who are visually impaired. |
Selwyn Paskowitz was driving six years ago when suddenly out of his
left eye he saw roadside lamp poles freakishly warp. Less than a year
later Paskowitz could no longer make out people's faces, and dusky
blotches like something out of a Mark Rothko painting marred his central
vision. "It was annoying," says the 65-year-old retired naval officer, a
bit stoically.
Paskowitz is one of nearly 9 million Americans
suffering from age-related macular degeneration, or AMD, the leading cause
of blindness in people over 50. Eight out of ten people with AMD have the
milder, "dry" form of the disease, but that can develop into the more
serious, "wet" form of AMD that accounts for 90% of the afflicted
population's vision loss. AMD can distort and block central vision within
days of its onset, or slowly darken the world over years. The television
drama ER ran a purplish three-episode story with Bob Newhart playing a
builder of architectural models who develops AMD, descends into depression
and finally puts a gun to his head. While there is no cure, sufferers can
still see well from the periphery and may be affected in only one eye.
The federal National Eye Institute in Bethesda,
Md. estimates that every year 260,000 people will develop the disease, and
the rate will increase as the population ages. "It's an epidemic," says
Frederick Ferris, an ophthalmologist at the institute.
Pharmaceutical companies have largely overlooked
AMD, spending more time and effort treating cataracts and glaucoma, the
latter of which affects 3 million Americans. Clinical trials for an AMD
drug cost ten times more than a glaucoma trial because the latest imaging
technology to examine the retina is expensive, as are the lengthy,
complicated tests to diagnose AMD.
The only AMD treatment on the market now is
Visudyne, a laser-activated drug from QLT Inc. and Novartis that stops
blood vessels from leaking. Approved three years ago by the Food & Drug
Administration, Visudyne treats only a particular type of macular
degeneration that afflicts 25% of all wet-AMD patients. Though it
generates $350 million in annual sales, Visudyne hasn't lived up to its
original hype, with most patients continuing to lose their vision.
But promising new treatments for macular
degeneration are on their way, emerging, in an unlikely twist, from cancer
research. Fighting both wet-form AMD and malignant tumors depends partly
on squelching new blood-vessel growth, a process known as antiangiogenesis.
In dry AMD vision is marred by yellow deposits called drusen. But in wet
AMD rogue capillaries invade the retina, the thin film along the back of
the eye that transmits images in the form of electrical signals to the
brain. The spreading blood vessels leak their plasma under the macula, a
quarter-inch-wide area that controls central vision. The macula swells and
scars, robbing the eye's ability to see directly ahead; peripheral vision
remains intact. "Macular degeneration is like cancer. You have very
aggressive, abnormally growing vessels that are hard to turn off," says
Carmen Puliafito, ophthalmology chairman at the University of Miami and an
unpaid adviser on Macugen, an antiangiogenesis drug now in testing.
Harvard Medical School's Judah Folkman pioneered
the field of angiogenesis in the 1960s, but it wasn't until 1989 that
Genentech researcher Napoleone Ferrara first isolated a protein crucial to
angiogenesis called vascular endothelial growth factor, or VEGF.
Genentech's first anti-VEGF drug, the colon-cancer fighter Avastin, has
huge expectations and is anticipated to be approved in 2004.
Macular degeneration drugs from Eyetech
Pharmaceuticals, Genentech and Genaera are all targeting VEGF. Genentech's
Lucentis, now in final-stage trials, is a chemical fragment of Avastin.
Ophthalmic giant Alcon Laboratories just completed a late-stage trial for
its drug Retaane, a modified steroid that targets enzymes produced by
stimulated blood vessels.
But the leading candidate right now appears to be
Macugen, from Eyetech, based in New York. In November the company released
results from a 1,200-patient trial. The drug, which is delivered through
an injection in the eye, improved vision in 6% of patients at the end of
one year, defined as the ability to read more than three lines on an eye
chart (22% were able to read at least one more line). More good news:70%
had less than a three-line loss of vision, compared with 55% in the group
that was given a sham injection. "The goal is to try to retain as much
vision as possible," says Puliafito. Eyetech could file for approval early
next year. If approved, Macugen could potentially treat all three types of
wet-form macular degeneration.
Founded in 2000 by ophthalmologists David Guyer,
43, and Anthony Adamis, 44, Eyetech has raised $143 million in venture
money and in September filed for a public offering. Guyer, who is chief
executive, and Adamis, chief scientist, declined to speak, citing the
company's regulatory "quiet period."
Macular Degeneration Diagram
Adamis had worked in Folkman's lab at Harvard in
the early 1990s and, in 1994, published his discovery that patients with
macular degeneration have high levels of VEGF protein in the affected
eyes, causing blood vessels to proliferate. His work caught the attention
of Nebojsa Janjic, a director of drug discovery at NeXstar
Pharmaceuticals, a biotech firm in Boulder, Colo. Janjic had developed a
cancer drug using an aptamer, or small string of synthetic RNA, that binds
to one of the five known forms of VEGF protein and prevents it from
docking to its receptor on the endothelial cell and sending out a signal
for vessels to grow.
But the aptamer didn't hold up to scrutiny,
failing to stop tumor growth in rats. Aptamers were also expensive to
manufacture. After reading Adamis' paper, Janjic guessed that the eye
might make a better candidate, since small amounts of the anti-VEGF drug
could be delivered locally, causing blood vessels to shrivel up.
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In 1996 Janjic met with Adamis, who, along with
colleague David Guyer, helped NeXstar design clinical trials for what would
become Macugen. In 1999 NeXstar enrolled the first patients, but then Gilead
Sciences acquired the company. Gilead, focused on antivirals, decided to sell
the drug. Guyer and Adamis were more than happy to buy it. In February 2000 they
formed Eyetech, raised $35 million in venture capital and licensed Macugen,
paying Gilead $7 million up front, with up to $25 million more in future
milestone payments, plus royalties.
Although only a handful of patients were tested for
three months, the initial results were very encouraging, with 25% of patients
able to read an additional three lines on an eye chart. The results excited
Pfizer enough that it agreed last year to pay up to $745 million to codevelop
and market Macugen.
The drug may still fail to win approval, and some
patients will squirm at the idea of getting poked in the eye with a needle every
month or so. Patients run the risk of infection, which can lead to blindness and
retinal detachment. In Macugen's trial 16 patients out of 890 injected developed
such complications. (Genaera's goes in the arm, and Retaane uses a blunt tube
that swerves around the eyeball). "I'm pretty sensitive when people start
messing with my eyes," says Paskowitz. "The treatment has to be 100% effective."
Macular Degeneration Diagram Link
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