Adelaide University researchers announced on June 27 the results of the first in-human trial of a new treatment for retinitis pigmentosa, a leading cause of blindness among working-age adults. The pilot study, conducted in collaboration with the University of Washington, tested whether a small molecule therapy could be safely tolerated by humans and showed promising early outcomes.
Retinitis pigmentosa is a genetic disorder where retinal cells responsible for detecting light malfunction, leading to progressive vision loss. Current treatments are limited, especially in later stages, and there is no cure. In this study, researchers injected a small molecule into participants' eyes. They observed that some damaged retina cells regained sensitivity to light even after normal light-sensing cells had been lost.
“This is the first clinical trial of a photoswitch drug in humans. Unlike gene therapies, which target specific mutations, this approach could potentially be used across many different forms of retinal degeneration,” said Professor Casson. “It also avoids the need for genetic modification, which simplifies treatment and may reduce risks.”
Participants reported short-term improvements on visual tests such as walking tasks; one participant with severely damaged retinal cells noticed increased awareness of light perception within two days after receiving the injection. Professor Casson said, “We found that the treatment was well tolerated, with no serious adverse events and no evidence of harmful effects on the eye.” He added, “We also saw early signals suggesting the drug may be having a biological effect—some participants reported changes in light perception, and brain imaging showed activity in visual areas of the brain following treatment.”
The findings have been published in Nature Medicine with industry support from Kiora Pharmaceuticals. A larger Phase 2 trial is currently underway to further evaluate whether this therapy can improve vision more rigorously.
“More broadly, this work establishes a new platform for vision restoration that could be developed further for retinal diseases beyond retinitis pigmentosa,” said Professor Casson.
