According to a small, preliminary clinic trial, it was found that injecting a common cold-like virus into the eyes of age-related macular degeneration (AMD) patients can halt and reverse the progression of the disease.
AMD is one of the leading causes of blindness in the US. Though this new finding has brought some hope in slowing down the disease, the results will need to be replicated in a much larger group of patients. Still, the early signs suggest that a single injection of the specially engineered virus can kick the body's natural immune response into action, clearing out the fluid that causes permanent vision loss.
The study, conducted by researchers at Johns Hopkins Medicine in Maryland, targeted a protein called vascular endothelial growth factor (VEGF), which is overactive in people with wet AMD (a rare and more severe form of the disease, which causes new blood vessels to grow beneath the retina and leak blood and fluid into the eye). Research shows that the build-up of fluid causes permanent damage to light-sensitive retina cells, prompting them to progressively die off, leaving blind spots in the center of a person's vision.
Treatments for wet AMD do exist, however, they involve getting injections in the eye once every four weeks. To maintain the benefits, you therefore have to keep up monthly injections for the rest of your life. The side effects of current medications available also include eye infections and an increased risk of stroke.
The team at John Hopkins demonstrated that in a handful of patients, there could be a way to halt and possibly, reverse the progression of wet AMD with a single injection. Though the preliminary study is small, results are a promising step towards a new approach that will reduce doctors visits, as well as the anxiety and discomfort due to repeated injections in the eye, and it has also been found to improve long-term outcomes.
Phase 1 of the clinical trial involved 19 men and women, older than 50 years, with advanced wet AMD. The men and women were divided into five groups that received increasing doses of a viral vector called AAV2 - a common cold-like virus that has been genetically engineered to penetrate the patients' retinal cells and deposit a gene that prompts the production of a protein called sFLT01. Once the virus has deposited the gene, the cells started to secrete sFLT01 which bound to VEGF and prevented it from stimulating leakage and growth of abnormal blood vessels. The aim is for the retinal cells infected by the virus to reproduce enough sFLT01 to permanently stop the progression of AMD.
Previous research has shown that sFLT01 can inactivate VEGF. However, until now, scientists had struggled to get the body to produce it on its own - instead they've had to regularly inject VEGF suppressing proteins to keep it in check.
In the clinical study, the first three groups were given the lowest doses of the AAV2 virus, and after they showed no negative side effects, the final two groups were given the maximum dose. It was reported that no severe side effects were reported in either of the groups.
Furthermore, it was said that even at the highest dose, the treatment was quite safe and no adverse reactions in patients were found.
The participants were selected based on their lack of response to all other standard treatment options - eight of which were unlikely to respond, even to their new treatment. From the remaining 11, four showed dramatic improvements after a single injection. It was reported that the amount of fluid in their eyes reduced from severe to almost nothing. A further two patients reported a partial reduction in the amount of fluid in their eyes. While the remaining five weren't as lucky. They experienced no improvement in vision after the injection. However, the researchers realized that their bodies naturally produced antibodies that attack the AAV2 virus.
Unfortunately, it will take a much larger clinical trial to figure out if the almost 50-50 chance of success in this study is an accurate indication of how the wider population will react to treatment. Nevertheless, the development seems promising, particularly when advanced AMD is expected to rise to 5.44 million Americans by 2050. In which case, treatment that works for only half of wet AMD patients could still change hundreds of thousands of lives.
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