Gene therapy could help treat millions affected with glaucoma

How gene therapy can help glaucoma patients

Glaucoma is a group of eye conditions that can eventually lead to blindness. However, the cause of vision loss in these conditions is the same, damage to the optical nerve caused by a build-up of pressure inside the eye.

The optical nerve is critical to vision since it transmits light signals from the eye to the brain. However, in the case of glaucoma, the build-up of unwanted proteins inside the eye results in the blockage of drainage channels. This leads to the accumulation of fluid inside the eye and the resultant pressure leading to damage to the head of the optical nerve.

Currently, topical eye drops are used to prevent the disease from progressing in glaucoma patients. However, there is also a subset of patients who develop resistance to the treatment.

Researchers at the Smurfit Institute of Genetics at Trinity College used a virus to infect the eye cells. The virus was genetically modified to include a gene for the synthesis of an enzyme called metalloproteinase-3, or MMP-3. The enzyme is a matrix protein and results in an increase in the flow of aqueous fluid from the front of the eye, thereby reducing the pressure inside.

The researchers conducted experiments in multiple models of the disease as well as in donor human eyes to test the efficacy of the treatment. Since the research was carried out in partnership with the industry, the experimental outputs were all directed toward translating the results into a clinical program for regulatory purposes.

“This exciting project allowed us to bridge the gap between academia and industry and work very closely with a gene therapy company to develop a cutting-edge therapy that we believe holds immense promise for patients in the future,” said Professor Matthew Campbell, Professor in Genetics at Trinity.

The researchers now plan to use the approach to treat other eye-related conditions as well. The research findings were published in the journal Science Advances.

Abstract:

Approximately 80 million people globally are affected by glaucoma, with a projected increase to over 110 million by 2040. Substantial issues surrounding patient compliance remain with topical eye drops, and up to 10% of patients become treatment resistant, putting them at risk of permanent vision loss. The major risk factor for glaucoma is elevated intraocular pressure, which is regulated by the balance between the secretion of aqueous humor and the resistance to its flow across the conventional outflow pathway. Here, we show that adeno-associated virus 9 (AAV9)–mediated expression of matrix metalloproteinase-3 (MMP-3) can increase outflow in two murine models of glaucoma and in nonhuman primates. We show that long-term AAV9 transduction of the corneal endothelium in the nonhuman primate is safe and well tolerated. Last, MMP-3 increases outflow in donor human eyes. Collectively, our data suggest that glaucoma can be readily treated with gene therapy–based methods, paving the way for deployment in clinical trials.