Information up-to-date as of February 2022
EPI-743 is a drug that is developed from vitamin E. It is a manmade quinone, like idebenone, and acts as an antioxidant. It is being researched in a number of conditions (such as Leigh Syndrome, Friedrich’s Ataxia and Pearson Syndrome). However, there is no current research in LHON and more research would be needed to find out if it would be a useful treatment.
As well as producing energy for cells, mitochondria are also involved in cell death. Cyclosporine A is a treatment that can help to prevent cell death caused by mitochondria. Because of this, it has been thought to be a possible treatment for LHON. Unfortunately, previous research testing cyclosporine A in people with LHON has been unsuccessful.
Brimonidine is a treatment that is routinely used to treat glaucoma (another eye condition involving damage to the optic nerve). Unfortunately, it has not been able to prevent vision loss in the second eye in the acute phase of LHON. However, it may be a potential treatment option for LHON carriers who are not yet affected with vision loss in either eye and who have glaucoma or ocular hypertension (which is an increased pressure in and around the eye). It is thought that this may help prevent vision loss being triggered by the increased pressure.
Stem cell treatment and regenerative medicine
The goal of regenerative medicine is to replace damaged or lost cells. Stem cell treatment is one form of regenerative medicine.
Stem cell treatment has suffered from bad press due to controversy over ethical issues and scam treatments. As there is currently no therapy for curing neurodegenerative eye conditions, the idea of using stem cells to replace damaged cells seems very attractive to those desperate for treatment. Unfortunately, some clinics prey on this desperation and offer unproven stem cell therapies. Travel to these clinics is often referred to as 'stem cell tourism' and it is common for these clinics to promise great benefits and downplay or ignore the risks. Find out more about the risks of bogus stem cell treatment here.
Various types of stem cells have been transplanted into mouse retinas, but it seems that more research is needed to get the stem cells to repair of damaged tissue in the eye. Researchers are trying to use stem cells to replace damaged retinal ganglion cells in conditions such as glaucoma. These would also be the cells targeted in LHON therapy.
In a clinical study in the US (The Stem Cell Ophthalmology Treatment Study (SCOTS)), 5 people with LHON received stem cell therapy and some improvement in their vision was seen. However, it is worth noting that the participants did not have the more common LHON mutations, and the treatment was early following the start of symptoms.
The research so far is very limited, and much more is needed to understand if stem cell treatment would be a suitable as therapy for LHON.
This useful website has lots of information about stem cells including current research, the challenges, and potential treatments.
EuroStemCell is funded by the European Commission and provides independent information and educational resources on stem cells and their impact on society.
Pharmaceutical activation of mitochondrial biogenesis
Recent research suggests that some LHON carriers are protected due to having a higher number of mitochondria. The research suggested that when the number of mitochondria exceeds a threshold, the LHON mutation does not cause optic nerve dysfunction that results in vision loss. Theoretically, activating mitochondrial biogenesis can increase the production of mitochondria and could be used as prevention in carriers, but this complex process is not yet fully understood.
Recent research suggests that the hormone oestrogen protects women who carry a LHON mutation and that targeting oestrogen receptors may avoid or delay the onset of the disease in mutation carriers. This could explain why males are more affected than females and suggests a therapeutic use for oestrogen in LHON patients. Although this is being considered as a potential treatment, it has never been clinically tested or proven in humans.
Bezafibrate, also known as Bezalip or Befizal, is a drug commonly used to lower the levels of fats in the blood, such as cholesterol. Some research studies have suggested that Bezafibrate can increase the number of mitochondria in cells. Bezafibrate has been trialled in patients with another mitochondrial disease, but the evidence was not strong enough to recommend bezafibrate as a treatment.
A trial to study the efficiency of bezafibrate in 14 patients with LHON is still ongoing. In this trial, bezafibrate will be tested for 1 year to determine if it can improve vision. The study is due to be completed in 2022.
A ketogenic diet (high in fat and low in carbohydrates) is thought to be a potential therapeutic option for people with LHON. A ketogenic diet mimics the state of ketosis; a process induced by starvation that burns fat instead of carbohydrates to produce ketones as a source of fuel. This is thought to have a protective effect that improves mitochondrial function. Although this is being considered as a potential treatment strategy, it has never been clinically tested or proven in humans.
The goal of gene therapy in LHON is to correct the genetic mutations found in the mitochondria. Gene therapy involves sending a healthy copy of the affected gene into cells.
In LHON and other mitochondrial diseases, gene therapy is very challenging as the therapy needs to be delivered to hundreds of mitochondria in each cell.
However, there has been research into therapies that target the nucleus of the cell (which is where genetic information for the cell is kept) instead of targeting the mitochondria directly. This can encourage the nucleus to produce proteins which can then be transported to the many mitochondria in the cell.
Proteins are complex molecules and perform many critical roles in the body. Genes contain the information needed to make these proteins. When there is a mutation in a gene, this can lead to problems with the proteins that the gene encodes for. The most common protein affected in LHON is called ND4. There are a number of mutations that affect the gene for this protein, including the common 11778 mutation. Because of this, gene therapy research at the moment tends to focus on ND4 mutations. People with other LHON mutations are not currently candidates for gene therapy. For more information on the mutations involved in LHON, visit ‘Genetics of LHON’.
GenSight Biologics is a privately owned biopharmaceutical company working on gene therapy for eye disorders. Their first clinical trial for a gene therapy, called GS010, for the treatment of LHON started in February 2014.
Clinical trials have since shown that GS010 is well-tolerated. There have been Phase 3 trials in people carrying the 11778 mutation who were treated with GS010 within 1 year of vision loss.
In general, people who took part in these trials experienced improvements in their vision. The results of these trials were encouraging but, as the vision improvements were variable, more research into gene therapy is still needed before it can be used as routine LHON treatment.
Each patient in these studies had the treatment injected into one eye and a sham-injection into the other eye. Despite this, the treatment effect was seen in both eyes, so it is thought that the treatment is able to move across to the second eye. However, a further clinical trial is researching the effect of treatment being injected into both eyes.
So far, research has only studied this gene therapy in people who have had vision loss caused by LHON for less than 1 year. Further research would be needed for those who have had vision loss for a more than 1 year
There is also an ongoing study looking at the long-term effects of this treatment.