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December
2007
During the past couple of years we have seen major advances in
our ability to treat choroidal neovascularization (CNV). Both Avastin
(bevacizumab) and Lucentis (ranibizumab) have been more effective
than previous treatments. These agents provide broad blockage of
isoforms of vasoendothelial growth factor (VEGF). Initial treatment
with these agents appears to offer better initial improvement than
Macugen (pegaptanib), which offers selective blockage of the VEGF.
In addition, Avastin and Lucentis are more effective than photodynamic
therapy (PDT), at least when used as monotherapy. The effect of
Anecortave Acetate appears to be similar to PDT.
What is unclear at this point is how long patients should receive
therapy and the long- term benefit of treatment. These anti-VEGF
injections clearly suppress CNV activity—at least while the
drug is still present. Some patients may do well with a short series
of injections without further recurrence. Unfortunately, recurrent
CNV is very common. Many patients require periodic injections to
maintain some degree of CNV suppression.
Triple therapy using PDT, a steroid injection, and an anti-VEGF
agent may allow some reduction in the number of total injections.
Investigations continue into other alternative therapies that may
require fewer injections. The VEGF-Trap (Regeneron) utilizes a
decoy receptor fusion protein which has a very high affinity for
VEGF. Phase III trials are pending. Another promising development
is protein tyrosine kinase (PTK) inhibitors. These small molecules
may offer broad suppression of CNV. Multiple companies are developing
potential drug therapies.
Another exciting development involves RNA interference to inhibit
production of VEGF. This eventually results in interference of
the mRNA responsible for VEGF production. Phase III trials are
underway to evaluate the RNA interference drug bevasiranib through
the COBALT trial. This trial allows all patients to receive initial
induction therapy using a series of Lucentis injections. Patients
are then randomized to receive either continuing monthly injections
of Lucentis or injections of bevasiranib every two or three months.
It is hoped that this treatment will allow fewer injections. We
are an investigative site for this new treatment and are currently
offering enrollment for select patients.
We have been pleased to offer our ARMD patients access to promising
new and investigational drugs and techniques for both the treatment
and prevention of CNV. Eyecare Associates of East Texas has a firm
commitment to ARMD clinical research and our patients have benefited
from treatment with drugs or therapies that would otherwise be
unavailable or cost-prohibitive outside of the context of a clinical
trial. As an investigative site for these trials, our patients
are able to receive these cutting-edge treatments locally without
the need for travel to major metropolitan centers. Over the years
we have been pleased to offer our ARMD patients enrollment in trials
involving PDT, Macugen, Anecortave Acetate, Lucentis, and various
combination therapies, among others.
The past few years of ARMD management have been exciting and ever-changing.
Treatment outcomes are certainly better than they have ever been.
Despite these advances we are sure that the best is yet to come.
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