By
Jonathan Yoken, MD
Newest
Treatments for Age Related Macular Degeneration
Overview
Newest Therapies
Lucentis
Avastin
For
over three decades, standard laser therapy was the only viable
treatment for patients with wet age-related macular degeneration
(AMD). This treatment, while a great breakthrough in its day,
had extreme limitations. Only about 25% of patients with wet AMD
were candidates for this treatment, and of those treated, about
50% would experience some form of recurrence of the disease. Almost
none of the patients who were treated with laser experienced improvement
of their vision, and in most cases slowing or stabilization
of the disease was the best one could hope for. Occasionally,
we still recommend standard laser treatment for our patients,
but in most cases, we will utilize one of our newer and more effective
therapies.
If you have
"wet" AMD affecting the middle of the macula, in some
cases, photodynamic therapy (PDT) is possible. This treatment
involves infusing a light sensitive drug (Visudyne) through your
blood stream similar to a fluorescein angiogram. This drug is
able to identify the new blood vessels, growing in the wrong place
behind the retina, that form with "wet" AMD. A "cold
laser" is then shone into the eye which activates the drug
stopping the new blood vessels from growing and helping to prevent
them causing too much damage to the macular area. The "laser"
does not burn the retina as it treats, thereby limiting any harm
to normal retina. This treatment has been shown to be effective
for some people with certain types (i.e. "classic) "wet"
AMD, but generally only improves vision about 5% of the time.
It generally slows the process of visual loss, and requires repeat
treatments, often about 3-5 treatments in the first year. See
article entitled "Photodynamic Therapy" for more information
about this therapy.
Newest
Therapies:
The newest
treatment modalities for wet AMD do not utilize any sort of laser.
These treatments are in a class of drugs called "Anti-VEGF"
therapy. VEGF stands for Vascular Endothelial Growth Factor, and
it is a protein that is important in forming new blood vessels.
This process can be useful in healthy individuals when new blood
vessels are needed, such as during wound healing or after a heart
attack, for example. In certain disease states, however, abnormally
high concentrations of VEGF can lead to damage by the growth of
new blood vessels where they shouldn't be, such as under the macula
in the wet form of AMD. This new class of drugs acts by blocking
VEGF and preventing it from stimulating the growth of these abnormal
blood vessels.
These drugs
need to be administered by injection into the vitreous cavity
(the center part of the eye). This is considered a minor procedure
and it can be performed in the doctor's office. Although this
sounds awful, almost all patients tolerate this procedure extremely
well. After the eye is anesthetized, most people feel no pain,
only slight pressure as the medicine is injected. In general,
the injections are very safe, with only a very small risk of ocular
side effects. In most cases, repeat injections are needed.
The first
new drug developed was called Macugen and was released in early
2005. It was truly a breakthrough in that it was the first in
its class and allowed us to treat most forms of wet AMD for the
first time. Its major limitation, however, was that it even though
it worked better than previous therapies (i.e. PDT and laser),
in the majority of cases, it still only slowed the disease and
required repeat treatment every six weeks indefinitely. More effective
therapies are now available and Macugen is seldom utilized anymore.
Lucentis
LUCENTIS™
(ranibizumab injection), was approved by the FDA at the end of
June 2006 for use in wet AMD. The initial results of a phase III
study utilizing Lucentis were reported in the summer of 2005.
The data reported demonstrated for the first time a significant
chance of improving vision in those patients recently affected
by wet AMD. The data actually demonstrated a 40% chance of vision
improvement at 1 year of therapy. It also demonstrated a 95% chance
of at least vision stability at 1 year. For the best results,
usually multiple injections are needed on a monthly basis for
at least 1 year. The frequency of injections can be varied to
some extent by your physician depending on your particular condition,
but the results, while still good, may not be as strong. The safety
concerns of Lucentis injection are small. There are some limited
side effects associated with the injection itself, including a
rare chance of infection (about 1/1000), cataract or retinal detachment.
Most of these side effects are treatable and in most cases did
not limit continuation of therapy. While Lucentis therapy is new,
there were no significant systemic side effects noted. The study
suggested that there might be a trend toward an increased risk
of thromboembolic events (i.e. stroke), but this trend was not
statistically significant. More information regarding Lucentis
can be found at Lucentis.com.
Avastin
Following
the reported benefits of Lucentis therapy in the summer of 2005,
retina specialists turned their attention towards Avastin, which
is a medicine currently FDA approved for the treatment of metastatic
colon cancer. Avastin is molecularly similar to Lucentis and acts
in the same way by binding the protein VEGF. The medicine helps
control metastatic cancer by blocking the blood vessel growth
required by new tumors to grow and spread. This is the similarity
to wet AMD in that new blood vessels grow underneath the macula.
Since Lucentis
wasn't available outside of clinical trials until this summer,
Avastin has been used for the past year with very promising results.
There have been a limited number of studies published that demonstrate
a beneficial effect, but its true efficacy is still unknown. There
has been no direct comparison of Avastin against other therapies.
Although it is believed Avastin is safe, there is no good controlled
study data to confirm this.
Your physician
may recommend using Avastin for your wet amd condition, but it
is considered "off-label" which means this use (in wet
amd) has not been evaluated by the FDA. Just because a therapy
is "off-label" does not mean it shouldn't be used, but
a thorough discussion with your physician is required to confirm
that this is the best of available therapies.
