Dublin biopharmaceutical company Genable Technologies has been granted orphan drug designation from the Federal Drug Administration (FDA) in the US for its gene therapy product GT308 that it is developing to treat the eye disease retinitis pigmentosa.
The move from the FDA is being regarded by the company as a significant milestone, as it will provide Genable Technologies with seven years’ market exclusivity once GT308 has secured regulatory approval.
Genable has grown from the work of Prof Jane Farrar, Dr Paul Kenna and Prof Peter Humphries at Trinity College Dublin (TCD). In 2011, the company secured €5m in financing from Fountain Healthcare Partners. Delta Partners is already an investor in the company.
Speaking this afternoon, Genable’s managing director Prof Alan Boyd said there is currently no treatment for retinitis pigmentosa.
"It’s an inherited, genetic disease. In Ireland, there are about 200 families with this condition. It’s related to the rhodopsin in your eye. Rhodopsin is a chemical that senses light. The rhodopsin is a chemical change that happens when light hits the rhodopsin molecule. That generates an electric signal which goes to the brain and you can see," he explained.
People with rhodopsin-linked retinitis pigmentosa have a mutation in the rhodopsin gene which causes their sight to worsen, eventually leading to blindness.
"What we can do with gene therapy is try to replace the defective gene," said Boyd. "The problem with retinitis pigmentosa is that it’s an inherited disease and it causes blindness. If you have got it – there are various degrees of severity with this disease – the chances are that people will be blind by the time they reach their late teens and early 20s."
The Genable group at Trinity College has been working on trying to create a gene therapy replacement that can be injected into the eye to replace the mutant gene.
However, Boyd said the problem here is that every mutation that occurs in a patient is slightly different.
"To develop a gene therapy we would have to go and find the specific mutation in their gene and then create a gene to correct it. It would have to be individualised."
This is where Genable believes it has come up with a breakthrough.
"We are actually going to use two genes. Firstly, we inject a suppression gene into the back of the eye. This suppression gene then produces a protein which turns off all the rhodopsin production in that individual. At the same time we also inject a gene which makes rhodopsin. The magic thing is this second gene is not turned off by the suppression gene. The one gene suppresses the faulty gene and the second gene replaces it," explained Boyd.
Orphan drug designation
Genable is engaged in pre-clinical trials, but the company hopes to be in the clinic to start trials with patients in the future.
As for the orphan drug designation from the FDA, Boyd said this will prove fundamental to the future development of Genable’s product. The company has already been granted orphan drug designation by the European Commission.
According to Boyd, there are about 300,000 people in the world with retinitis pigmentosa. Of those, there are about 170,000 people with the condition in Europe and about 100,000 people in the US.
Orphan drug designation is granted to help advance the development of therapies to treat rare diseases, such as retinitis pigmentosa. Once you get orphan drug designation, Boyd said regulatory organisations, such as the FDA, help companies develop their products to get it through to market.
"The most significant thing is that in the US we get seven years of market exclusivity once the product is approved. By giving this exclusivity it means we have a longer time to recover our cost of development," he added.