Age-Related Macular Degeneration (AMD) - Therapy / Treatment
AAO Reports - Day Two
Reporting directly from the Retina Subspecialty Days at the annual meeting of the American Academy of Ophthalmology conference in Orlando, Florida.
The second group of reports includes Internal Radiation for AMD and an overview of a wide range of upcoming therapies, as well as an update on artificial vision.
Internal Radiation for AMD
It's been a long road for radiation and AMD, but now it appears that something may work. Radiation has the ability to prevent blood vessel growth. Various forms of radiation (external, Proton Beam) have been used as experimental treatments in the past with mixed results. In particular, the external beam radiation did not work for many patients and sometimes encouraged cataract growth.
Dr. Pravin Dugel from Doheny Eye Institute in Los Angeles presented information about an internal radiation therapy from NeoVista, called epimacular brachytherapy. We had hoped at this meeting to hear two year results from a clinical trial of almost 500 patients. But, since the last patient received the last exam just weeks ago, the data is not available. Instead, he discussed the results of an earlier trial of the treatment which showed positive results. The rest of the data will be available soon.
This therapy involves a surgery during which a source of radiation is introduced into the eye and held in place over the macula. It only stays there for 4 minutes and then is removed. This is a single treatment of the radiation and is not repeated. It is combined with Lucentis with the intention to reduce the number of injections needed.
The people in the trial are those who were not doing well with injection therapy. Prior to entering the study, all patients received a round of Lucentis injections. Then,in the clinical trial, one group of patients received the radiation and 2 injections of Lucentis (at the beginning of the trial and then one month later. The other group received the radiation and once a month injection of Lucentis for the first three months, followed by "as needed" injections.
Overall, 61% of patients maintained their vision and 32% gained vision. Interestingly, the patients who improved the most had the fewest number of injections. Fifteen of the patients didn't need any injection after the first ones.
It will be interesting to see the two year results of the large study. Hopefully, patients will need just one surgery with radiation and a much reduced number of injections.
There are other studies underway, which are needed to verify the results. The company hopes to submit the treatment to the FDA by the end of the year.
Future Therapies for Wet AMD
Dr. Jason S. Slakter from New York presented a very fast run-down on all the wet AMD treatments under investigation - and there are many!
If you don't want to read the details, the bottom line is that none of these are ready for patients yet and some are only in very early trials. Still, it is very exciting to see how much work is being done to address wet AMD and find better therapies. There are many pathways that contribute to wet macular degeneration; the treatments available now are all focused on the end of that pathway after the damage is being done. Those studies are continuing, but now researchers are looking at other points in the pathway to see if they can stop things before they even start.
Treatments aimed at the end of the pathway include Lucentis and Avastin. They block the growth factor VEGF which that promotes blood vessel development. So far, all of these still involve an injection in the eye. The newer ones include:
- KH902 - a protein that is in a Phase I trial in China and shows marked improvement in vision. Remember that larger clinical studies need to be done before we really know if it works.
- MP0112 - another protein in a Phase I trial, but it works in a slightly different way.
Gene therapy is being developed. These essentially insert a treatment or drug into a gene, causing a change in the way the gene behaves. SFLT01 is one of these and is in a Phase I trial.
PDGF is another growth factor that contributes to wet AMD and needs to be stopped. E10030 is one treatment being tried. A Phase I clinical trial showed improvement in vision over 12 weeks and positive anatomic results. Phase II is underway but results are not available.
Newer experimental therapies are trying to interfere with the degenerative process and to catch things before the VEGF is even produced.
- Sirolimis is one of these and is in a Phase I trial right now but is not recruiting patients.
- Pazopanib is a broader treatment and did improve vision in patients in a Phase II study. We need more data on this and then hopefully it will move into a larger Phase III trial and be closer to approval.
Timed release therapies are on the horizon. There are a variety of drug delivery systems under development that would insert something into the eye that would leak out treatment over several years. Some require an initial surgery to place the implant; others are so tiny that the implant is simply injected into the eye. Potentially, these treatments would be done every 1-3 years.
Bionic Vision/Artificial Vision
Dr. Mark Humayun provided an update on the Second Sight Argus II device. This collaborative research has implanted an array of electrodes into blind eyes. It is attached to a camera mounted on a pair of glasses. The image is sent from the camera to the array and then up to the brain, where vision occurs. Subjects have gained some vision and in general can move around safely and identify objects that are high contrast (like a black hat on a white wall). Some are able to see letters if they are high contrast.
The researchers in this project are still trying to create an array with more and more electrodes, which would allow better vision and potentially almost normal vision. But there are technical challenges to doing this and the progress is slow.
There is another type of implant being used in Europe that will be presented later.
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Macular Degeneration - A Closer Look