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Avastin and Lucentis for Retinal Vein Occlusion and
Diabetic Macular Edema
Anti-VEGF drugs have changed the
landscape of eye care. They’re not being used
exclusively for macular degeneration any more.
By now, most people, especially those suffering from
wet macular degeneration, have heard all about
the latest injectable eye medications –
Macugen,
Avastin and
Lucentis.
This new family of drugs has changed the way
vitreo-retinal ophthalmologists treat macular
degeneration,
diabetic retinopathy and some other
common eye
problems. They are called anti-VEGF drugs.
Vascular Endothelial Growth Factor (VEGF) is a
naturally occurring chemical in the body. One of its
purposes is to stimulate the growth of new blood
vessels in order to repair damaged cells that need
tissue-healing oxygen – for example, cases of cancer
or age-related macular degeneration (AMD).
In “wet”, or neovascular AMD, abnormal,
hyperpermeable blood vessels (choroidal
neovascularization - CNV) grow out through the
age-damaged Bruch’s membrane, below the retina, and
up into layers of the outer
retina.
When VEGF over-expresses, it can
actually contribute to cell damage, especially in
AMD, where the abnormal new blood vessels leak and
hemorrhage into the retina causing scarring,
swelling and
detachment of the
retinal
pigment epithelium. These conditions will cause
markedly rapid vision loss that is quite noticeable,
if not debilitating to the patient.
Anti-VEGF
drugs work by adhering to upregulated VEGF,
preventing it from binding to its receptors. This
inhibits upregulated VEGF and slows the progression
of CNV associated with neovascular AMD.
These drugs are
injected intravitreally,
typically on a regular basis. Once treatment is
started, the patient will need to commit to regular
visits to the retina specialist for treatments.
Unless some form of extended-release system is
perfected and approved, there is no readily
available way around this inconvenience.
Not just for AMD
Ophthalmological use of Anti-VEGF drugs was
originally FDA-approved for the treatment of
neovascular AMD. However, recent studies have
demonstrated that anti-VEGF drugs can be used safely
and effectively for a number of retina conditions
that involve macular edema as a secondary
complication. Common
eye diseases, such as
diabetic
retinopathy, cause permeability of weakened retinal
blood vessels. The result is blurry vision and
subsequent macular edema.
Recently,
ophthalmologists have employed anti-VEGF drugs with
great success in treating macular edema. At my
Palm
Harbor vitreo-retinal practice,
The Macula Center, I
have employed anti-VEGF therapy since the first drug
of its kind was FDA approved and introduced to the
market. I have treated dozens of diabetic
retinopathy patients with
Avastin and have realized
excellent results. Some of these patients had
undergone years of
retinal laser treatments,
prednisone drops and
Intravitreal steroid injections
with limited results.
On Trial
One frustrating retina condition,
central or
branch retinal vein occlusion (CRVO / BRVO), can
involve severe secondary macular edema that can take
more than a year of steroid therapy to get under
control.
The CRUISE trial, which was conducted at
The
Methodist Hospital in Houston, demonstrated a
significant increase in visual acuity in CRVO
patients who received Ranibizumab (Lucentis - a
popular anti-VEGF drug) injections every month for
six months. In fact, the data showed a statistically
significant increase in acuity at 1 week after the
first injection. These dramatic results are unheard
of using traditional treatments like prednisone eye
drops.
In addition to the prospective,
randomized CRUISE trial,
Genentech is in a phase III
study of its drug Ranibizumab for treatment of BRVO.
The results of this Lucentis trial will form the
basis of a supplemental biologics license
application being submitted to gain FDA approval for
BRVO treatment.
Technology
At The Macula Center, we use
Optical Coherence
Tomography (OCT) to measure central macular
thickness in patients undergoing anti-VEGF therapy.
These high-definition, objective and topographical
studies allow us to track the successes and
deficiencies of each treatment on each individual
patient.
I am also working with a well-known
electronic medical records firm to create automated
progression graphs on both individual patients, and
my entire patient population collectively. The
software will utilize our existing EMR data to
demonstrate trends of success and weaknesses in
different treatment scenarios. The value of such
readily available research data will prove
immeasurable in terms of customized patient
treatment at our practice.
What’s
next?
Seeking to address the issue
of never-ending, inconvenient monthly treatments,
there is a Pharma movement toward novel
implantations of extended-release devices for
delivery of biodegradable ophthalmic implants that
will continually release active agents.
Although an anti-VEGF implant has not yet gone to
market, biodegradable implants containing
corticosteroids have. These are in the early stages
of acceptance and usage in the ophthalmic community.
Complications like
cataract development and
intraocular pressure issues must be studied and
validated.
Conclusion
There has never been a more vibrant era in
vitreo-retinal ophthalmology. The landscape of a
retinal specialist’s workflow is enormously
different than it was five short years ago, thanks
to medical advancements.
Today’s patients
benefit from the pharmaceutical companies’
race-to-market of improved anti-VEGF drugs, their
possibilities and applications. The ideas and
theories of what retina medicine needs next are
cascading from pharmaceutical research labs and
practitioners. The future of vitreo-retina disease
treatment is limited only by the amount of dollars
that will be invested in getting these drugs and
treatment devices to market.
The future of
the retina patient looks brighter than ever.
Illustrations courtesy of
www.JirehDesign.com
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COPYRIGHT © 2007-2010, THE MACULA CENTER, LLC, ALL RIGHTS RESERVED
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