Have you, a parent, or a grandparent been diagnosed with Age Related Macular Degeneration (ARMD)? Have you experienced loss of central vision? Has your loss of vision been rapid?
Wet ARMD is the less common, but more visually debilitating type of ARMD, also referred to as Exudative ARMD. This type is characterized by the formation of Choroidal Neovascularization, which is formation of new, fragile blood vessels under the Retina.
These new blood vessels can leak fluid or blood and cause a precipitous loss of central vision. A diagnostic test in which dye is injected into your arm in order to study the flow of this dye as it enters your eye, known as Fluorescein Angiography (FA), can be used to detect leaking and bleeding of these vessels.
Retinal specialists use FA findings to categorize the severity of the disease and predict the outcome. Although the exact mechanism for the development of ARMD is not well understood, it is increasingly clear that Vascular Endothelial Growth Factor A plays an important role in the development of Neovascularization and the vessel leakage that leads to central vision loss.
Ranibuzumab (Lucentis®) was FDA Approved in 2006 after multicenter trials demonstrated its superiority to Pegatanib (Macugen®). Lucentis® administered in intravitreal injections every 4 weeks remains the gold standard for the treatment of Wet ARMD.
What are some of the advantages of Lucentis® use?
Lucentis® is a humanized monoclonal antibody fragment designed to bind and inhibit all forms of Vascular Endothelial Growth Factor A. This type of antibody is created by the fusion of tumor cells and human cells that produce an antibody, resulting in a “hybridoma,” which will continually produce antibodies.
The term monoclonal is used because they come from only one type of cell, which is the hybridoma. By contrast, polyclonal antibodies are prepared using many kinds of cells.
The problem with polyclonal antibodies is that these agents do not only attack the foreign substance but the body’s own healthy cells, creating undesirable side effects. Monoclonal antibodies attack the target molecule and only the target molecule, with no or greatly reduced side effects. Two Phase 3 clinical trials revealed that Lucentis® administered in monthly intravitreal injections stabilized visual acuity in 90-95% of patients, regardless of lesion subtype, and improved vision in one in three cases. The gain in vision was sustained over the course of Lucentis® treatment (1 to 2 years).
What are some of the disadvantages?
The biggest drawback to is cost. One injection costs $2,000.00. This means that the 12 injections per year found beneficial in clinical studies would cost a whopping $24,000. Tied closely to cost is the frequency of treatments. Since ARMD patients are older, coming in for treatment can represent a hardship, particularly for individuals with significant mobility or cognitive deficits.
Less frequent dosing of Lucentis® was studied in the PrONTO study (Prospective Optical Coherence Tomography [OCT] Imaging of Patients with Neovascular ARMD).
The protocol for the study was administering monthly intravitreal injections for the first 3 months to ARMD patients followed by as-needed dosing based on monthly evaluations of visual acuity, Optical Coherence Tomography imaging of retinal thickness, and fluorescein angiography evaluation of retinal leakage.
The study was a small, single center study. Despite the fact that patients in this study did appreciate the decreased number of injections, and gains in vision were achieved, a large body of data supports the need for frequent administration of Anti-VEGF Therapy in order to maximize visual gains.Higher doses of Lucentis® for Wet ARMD may be of limited benefit in the long-term because of the short duration of these drugs. Even a quadrupling of drug concentration appears to extend the duration of therapeutic levels by a week or less.
More research is being undertaken to explore higher dosing which may benefit certain subsets of Wet ARMD patients who do not fully respond to standard regimens.
In a similar way that Genetic Advances are paving the way for customized medical therapy based on the patient’s unique genetic make-up, individualizing treatment with Anti-VEGF Therapy is being studied.
Your eye doctor may explain that you will be monitored closely to see how you respond to treatment and that your treatment will be tailored accordingly. More than likely, you will be very motivated to follow your treatments when you notice vision loss that results when you try to “stretch out” your visits.
Return From Lucentis to Macular Degeneration