Drugs for cancer and alcoholism show promise for RP

Investigating the potential of drugs already licensed to treat other conditions can be a particularly efficient and cost-effective strategy.

Called drug repurposing, this approach means that researchers can consider the known properties and actions of a drug alongside the mechanisms of a particular disease, and make a reasonable assessment as to whether drug might provide a potential remedy. Drug repurposing also means that the side effects and safety profile of the drug are already well known. However, preclinical laboratory work and clinical trials for the new target condition are usually still required.

Here at Retina UK, a couple of recent stories about potential drug repurposing have caught our eye.

Methotrexate is a powerful drug already used to treat certain types of cancer, as well as autoimmune diseases such as rheumatoid arthritis, but scientists have also discovered that it can improve the function of faulty rhodopsin protein. Rhodopsin plays a key role in enabling light sensitivity in rod photoreceptors, and some cases of retinitis pigmentosa are caused by mutations in the rhodopsin (RHO) gene. US biotechnology company Aldeyra Therapeutics is now starting a small clinical trial of methotrexate for autosomal dominant RP caused by a particular mutation in the rhodopsin gene, with the drug being injected into the jelly of the eyeball. For more details, see www.fightingblindness.org/research/aldeyra-launches-phase-2-clinical-trial-of-methotrexate-intravitreal-injections-for-rp-251.

Meanwhile, knowledge of the biochemical targets of a drug normally used to treat alcoholism has led scientists to investigate whether it might be helpful in retinal disease. In a study on mice with retinal degeneration, the drug, called disulfiram, helped restore some vision by dampening down nerve signal “interference” from dying photoreceptors. The US-based scientists are now planning a small clinical trial in people with relatively advanced RP. For more details, see www.urmc.rochester.edu/news/publications/neuroscience/a-key-to-restoring-sight-may-be-held-in-a-drug-that-treats-alcoholism.