Stevens Is Developing a Promising New Treatment Method for Age-Related Macular Degeneration
Researcher works with universities of California-Davis, Illinois, Wisconsin and others to engineer and test a novel microsphere-hydrogel delivery for medicine, requiring fewer injections, to treat a common vision complication of aging
AMD, or age-related macular degeneration, is a common and dangerous complication of aging where the central area of one’s vision becomes distorted.
Some 20 million Americans are believed to be affected by two types of AMD: dry and wet forms. Wet, or neovascular, AMD causes severe vision loss due to a combination of abnormal blood vessel growth and leaking that eventually damages the macula.
“Treatments are available, but these usually involve repeated injections into one’s eye in a doctor’s office,” explains Stevens professor Jennifer Kang-Mieler, a noted expert on therapies for eye conditions.
Anti-vascular endothelial growth factor (anti-VEGF) medication is an effective treatment for wet AMD. The medication prevents the growth of aggressive new blood vessels. However, the injections must be given frequently to be effective, sometimes up to seven or eight times in the first year.
“We have patients who have been getting the injections regularly for over 17 years. Multiple visits and injections take time, cost money, can be uncomfortable for patients and raise the risk of complications. This is a significant treatment burden.”
But now, with support from the National Institutes for Health (NIH), Kang-Mieler and her collaborators may be building a better AMD treatment.
Specially prepared doses, released over time
Kang-Mieler, chair of the university’s biomedical engineering department and holder of multiple NIH research grants, has been pioneering new therapeutic technology to deliver anti-VEGF more effectively with less injection frequency.
Working with collaborators including the University of California–Davis, Illinois Institute of Technology, the University of Wisconsin and the University of Illinois at Chicago, Kang-Mieler has developed a drug delivery system (DDS) that could make treatment easier, more comfortable, more affordable while delivering the same effectiveness.
“We’re very excited by these results,” she says, “which involve the novel formulation and engineering of therapeutic microspheres suspended in a hydrogel. We have evidence now that these injections may remain effective for as long as six months or longer.”
Previously, Kang-Mieler has demonstrated extensive characterizations, safety and treatment efficacy in small-rodent models. Building on her previous work, the team recently reported in the journal Drug Delivery [32:1, 2460671] that the new DDS system is safe in a non-human primate model.
Aflibercept (an anti-VEGF agent) was loaded into the DDS and injections were then made into the eyes of 23 rhesus macaques housed at the California National Primate Research Center by a trained veterinary ophthalmologist; macaques possess eyes highly similar to human eyes. A subset of animals received a second DDS at nine months and were followed for two years.
Clinical exam, retinal imaging and electroretinography were conducted at regular intervals to ensure that there were no eye injuries or side effects due to DDS injections.
“These tests revealed the DDS was indeed gradually degraded over time and released the drug, as expected, with no behavioral changes nor significant structural and functional changes in their eyes,” notes Kang-Mieler.
“We found no evidence of inflammation, uveitis, retinal degeneration or cataracts, for instance. Our finding is significant, as it demonstrates that our DDS is safe.”
The researchers did note one animal experienced a serious adverse event due to contamination of deionized water and a small number of animals displayed toxic anterior segment syndrome (TASS) — though TASS is seldom found clinically and was unlikely to be due to the DDS injections given.
What’s next? Kang-Mieler hopes to test the system next in the choroidal neovascularization primate model, which mimics human wet AMD. The team anticipates that DDS-treated eyes would have a positive impact on reducing neovascularization in the monkey eyes.
“That’s the next step, to know if this drug delivery system works well in a wet AMD large animal model to show the treatment efficacy,” she concludes. “In the near future, we hope to start human trials.”