Therapies being Studied for Dry Age-Related Macular Degeneration
Report from the annual ARVO (Association for Research in Vision and Ophthalmology) meetingMay 3, 2011 - Studies of two potential treatments for dry age-related macular degeneration have been presented at the 2011 ARVO conference. Both studies are phase 2 trials, designed to confirm dosage levels and gather early evidence about the drugs’ effectiveness. The positive results presented here mean that both drugs are likely to proceed to phase 3 trials – large-scale trials where investigators obtain all of the evidence necessary to have a drug approved for sale.
NT-501 - Developed by Neurotech
NT-501 is a treatment designed to protect, and in some cases rescue, dying photoreceptors in the retina in order to preserve vision. This treatment relies on a growth factor produced by the human body called neurotrophic factor (CNTF). Human cells engineered to produce CNTF are implanted in the eye in a tiny specially designed capsule which protects these cells from the patient’s immune system and continually releases a small amount of the growth factor.
Fifty-one people were involved in this trial which took place in several cities. Participants received a high dose of CNTF, a low dose or a placebo (no treatment). The high dose proved the most effective with over 96% of people in the high dose group having their vision stabilize. Stable vision was defines as losing less than 15 letters on an eye chart in a one year period. Only 75% of people receiving no treatment had stable vision. People who entered the trial with relatively good vision (20/63 or better) had modest improvement in their sight and all had their vision stabilize. Eye examinations of people on the higher dose also showed positive changes, and the size of the damaged area of the retina decreased. There were no serious ill effects associated with the treatment or with having the capsule implanted.
Similar findings were also published in the Proceedings of the National Academy of Sciences in late March. At that time, company spokespeople suggested that the results warrant further larger scale studies to confirm the value of the treatment. NT-501 is also being tested as a treatment for other retinal degenerative disorders including retinitis pigmentosa.
Fenretinide - Developed by ReVision Therapeutics
Early results from a phase 2 clinical trial of the dry AMD drug fenretinide were also presented at the 2011 ARVO conference.These findings build on a previous presentation about the study at the Annual Meeting of the American Academy of Ophthalmology last fall.
This study involved 246 people in different US cities taking two different doses of fenretinide (100 mg or 300 mg). Fenretinide is an oral drug taken once daily. Fenretinide reduced the risk of a person with dry AMD developing the more dangerous wet form of AMD by approximately 2.2 fold. (Wet AMD is responsible for 90% of AMD related vision loss). Previously presented work has also suggested that the area of the retina damaged by dry AMD expands more slowly in people who respond to the drug.
Based on this information, these scientists conclude that fenretinide may be useful to slow, or prevent, the conversion from dry to wet AMD. They also hope to move forward on a larger phase 3 clinical trial to evaluate this therapeutic effect in a larger patient population.