Potential agents take several different paths in terms of their therapeutic benefit
Potential treatments for the management of dry age-related macular degeneration (AMD) are numerous, but so far, studies are still ongoing as to their therapeutic benefit, said Dr David S. Boyer, at the Macula 2011 and Atlantic Coast Retina Club meeting of the Wills Eye Institute.
"Currently, the only approved treatment of dry AMD is the use of vitamins based upon the results of the Age-Related Eye Disease Study (AREDS) that showed a reduction of both a loss of visual acuity and of progression of dry AMD," said Dr Boyer, who is with Retina Vitreous Associates Medical Group, Los Angeles, and a clinical professor of ophthalmology, University of Southern California/Keck School of Medicine, Los Angeles, California, USA. "Patients with geographic atrophy, however, did not seem to have a reduction in formation or progression."
Several neuroprotective agents are currently under investigation for the treatment of dry AMD. Among them are NT-501, brimonidine tartrate and topical tandospirone.
Using encapsulated cell technology that permits CNTF-producing transfected RPE cells to be implanted into the vitreous cavity, this agent has a sustained-release platform that produces CNTF for a year or longer. The phase II study is completed and data analysis did not show a statistically significant decrease in growth of the geographic atrophy. However, it did show a trend toward improvement in both macular volume measurements and vision in patients with good beginning visual acuity, compared with control or low dose, Dr Boyer said.
Other neuroprotective agents currently under investigation for dry AMD include a brimonidine tartrate intravitreal implant (Allergan) and topical tandospirone (Alcon Laboratories).
Reduce byproduct accumulation
Amyloid beta has been discovered in pathologic studies of drusen. Based on this observation, several compounds that reduce the accumulation of amyloid beta are being studied. Two currently under investigation include glatiramer acetate and RN6G (PF-4382923) a humanized monoclonal antibody versus ABeta40 and ABeta42.
Glatiramer acetate (Copaxone, Teva Pharmaceutical Industries) is a treatment approved by the FDA to treat multiple sclerosis. This agent may reduce drusen over a period of 3 or 4 months when patients are treated with weekly injections. Its effects may be neuroprotective, and currently, several small studies are under way to examine this as a potential treatment.