25 May Radiation and Lucentis Combined to Treat Macular Degeneration
External beam radiation and Lucentis may be combined to treat wet macular degeneration. The results showed the treatment may be very safe and, when combined with anti-VEGF injections such as Lucentis, may decrease the need for frequently repeated injections.
Neovascularization, the growth of abnormal blood vessels, underneath the macular defines “wet macular degeneration.”
Radiation Kills Cells
Radiation treatments have been used in and around the eye to treat tumors. Radiation, in this case, halts the replication of cells. In the case of tumors, the lesions can no longer grow. So too, with neovascularization, new growth is inhibited. This is not the first study that has investigated the use of radiation for wet macular degeneration, but this is one of first trials combining external beam radiation with Lucentis.
Side Effects of Radiation to the Eye
Radiation can be toxic to the eye. It can cause cataracts, damage to the optic nerve and retina. It may also damage the lacrimal (produces tears to the eye) system and cause dry eye.
The investigators were able to dose and administer the radiation safely, seemingly able to avoid the usual complications of external beam radiation.
Treatment Required Fewer Injections of Lucentis
The gold standard for treating wet macular degeneration is now injections with either Lucentis or Avastin. The injections, however, need to be repeated as often as monthly. While highly successful, the need for repeated treatment requires a lot of trips to the office and can be expensive.
The study combined the use of the popular anti-VEGF agent, Lucentis (ranibizumab). The design of the trial required 2 initial injections during the first month of treatment.
52% of patients did not require additional injections for the 12 month study period (they only had 2!).
Also noteworthy, most patients stabilized and actually improved their vision.
What Does This Mean? This is not an approved treatment. It is in no way a true “study,” but this small trial still has some merits. It provides us with a small amount of evidence that alternative treatments using radiation may be useful.
First, recall that anti-VEGF injections, such as Lucentis or Avastin, now standard therapy for wet macular degeneration, were developed for chemotherapy against several types of cancers. The discovery that this improved patients with macular degeneration was coincidental.
For instance, patients receiving chemotherapy for colon cancer started noting improvement in their vision. Evidently, these patients had both cancer and wet macular degeneration.
External beam radiation has long been used for many types of cancer treatments.
In both cases, agents that halt rapidly dividing (i.e. growing) tissues should be effective in both the cancer treatment and the eye disease. The radiation stymies cell replication and the Lucentis (anti-VEGF) inhibits grow of new blood vessels. In the case of cancer, a tumor can not enlarge without blood supply.
So, it makes sense that this may work.
Lastly, this really underscores the need for treatments that do not need to be repeated so frequently, such is the case with Lucentis and Avastin. Right now, most doctors inject as frequently as every 4-6 weeks! Drug delivery systems designed to release drug over an extended period may aid this as well.
Aissa DirawatunPosted at 12:36h, 28 May
In eye tumors, I’m assuming, its easier to pinpoint the exact location of the radiation treatment, however, I can not grasp the concept of using radiation on wet AMD because its location is not localized in one area.
How does the doctor aim the radiation? If the hemorrhage is on the area of the macula, wouldn’t radiation kill the healthy cells in the same vacinity? Wouldn’t that create a larger central blind spot for the patient?
I’m trying to get my head around the concept.
Randall V. Wong, M.D.Posted at 06:21h, 29 May
In most cases of wet ARMD, the neovascular “membrane” is actually seen as a well defined cluster of tissue. Sometimes this is not apparent when looking directly at the retina and is more easily seen on fluorescein.
The short answer is that there is a target for the radiation.
Thanks. Great question.