A small, preliminary clinical trial conducted by researchers at Johns Hopkins and collaborators has demonstrated an experimental gene therapy that utilizes specific viruses to introduce a therapeutic gene into the human eye is completely safe, which means that it could be effective in saving the vision of people, who have been diagnosed with wet age-related macular degeneration (AMD). Nearly 1.6 million people living in the United States have experienced vision loss related to AMD. The condition is marked by the growth of aberrant blood vessels that will leak fluid into the center of the visual field or macula. The macula is utilized for recognizing faces, driving and reading.
The study reports a powerful, new approach where a virus that is similar to a cold, but modified in the lab to prevent it from causing disease, is utilized as a gene carrier and injected into the human eye. The virus is capable of penetrating the retinal cells and depositing a gene that transforms the cells into workshops for the production of sFLT01, a therapeutic protein.
Abnormal blood vessels, which are linked to the development of AMD, grow as the patient begins to experience an increased production of vascular endothelial growth factor or VEGF within their retinas. Currently the disease is being treated with an injection of proteins, administered directly into the eye. The proteins bind and inactivate VEGF to reduce fluid in the macula and in turn improve vision. A downside to the treatment is the therapeutic proteins will exit the eye over a 30-day period, leaving patients no other alternative but to return to the ophthalmologists’ office to have the injection repeated every six to eight weeks to prevent vision loss.
Ophthalmologists say the discomfort and burden of the treatment regimen is deterring patients from getting injections as often as they should, leading to vision loss.
The virus utilized in the study was designed to target retinal cells and supply them with a unique gene that is capable of producing sFLT01. The experiment was carried out in this manner since viruses naturally penetrate cells and deposit noticeable genetic material. Therefore, the retinal cells transformed into workshops producing the very important therapeutic protein – possibly eliminating the need to have the protein injected repeatedly.
“This preliminary study is a small, but promising step towards a new approach that will not only reduce doctor visits and the anxiety and discomfort associated with repeated injections in the eye, but many improve long-term outcomes because prolonged suppression of VEGF is needed to preserve vision and that is difficult to achieve with repeated injections because life often gets in the way,” says Peter Campochiaro, M.D., the George S. and Delores D. Eccles Professor of Ophthalmology at the Johns Hopkins University School of Medicine.
The study was published in The Lancet on May 16, 2017.