LHON Treatments

As of 2015 there is no proven clinical therapy for Leber Hereditary Optic Neuropathy.

A big problem with developing a therapy is that doctors cannot predict who will lose eyesight due to0 LHON before it happens.

Researchers are looking at some therapies, but they need to test them on people who have already lost some eyesight.  They test if the therapy protects the remaining fibres of the Optic Nerve and so stops the person from losing more sight.

They test the therapies using very sensitive instruments to measure the thickness of the nerve cell layer in the retina, and so the number of Optic Nerve fibres still active.

There are four main classes of therapy.

Protective Therapy and Antioxidants

Doctors recommend that anyone with a LHON gene mutation sticks to a “healthy” diet rich in natural antioxidants such as Vitamin A, Vitamin C, Vitamin E, Selenium and so on. These are the best known “antioxidant” nutrients, but in fact there are many of them.  It is better to eat a diet with plenty of fresh fruit and vegetables and so get a wide mix of all of the chemicals, rather than a diet supplement with just one or two of them.

Antioxidants are chemicals that work together to safely pass high-energy protons around the cell.

LHON Doctors do NOT recommend taking large doses of any one antioxidant.  The human body needs all of the antioxidant chemicals as they work together inside every cell in the body.

Dr Alfredo Sadum used the analogy of a line of people forming a bucket chain to pass water. Each person represents one of the antioxidant chemicals working together.

A bucket chain representing antioxidants in the cell passing protons from one to another safely
A bucket chain representing antioxidants in the cell passing protons from one to another safely

A healthy diet is like all of the people in the chain are there to pass water along the chain.

Antioxidant bucket chain with one huger person

Taking a lot of one antioxidant, is like having one person in the chain replaced by a giant. He can’t fill his bucket any quicker, because he has to wait for the person before him.  He can’t pass water any quicker than the rest of the chain.

You should ask your doctor before taking any diet supplement or chemical. There are three very good reasons for this:

1) Some diet supplements or other chemicals are very dangerous, and you could end up doing more harm than good.   Even some vitamins are poisonous if taken in high doses.

2) Fake drugs and diet supplements are very common, especially if you buy them over the Internet. You may think you are taking something safe, but it may be a fake with unknown ingredients.

3) If your body already has enough of some chemicals such as  vitamin C, the excess is simply excreted in the urine.

Chemical Therapies

Doctors do not know exactly how LHON damages the cells in the eye yet, but they are pretty sure that at least part of the damage is caused by the way high-energy protons are handled inside mitochondria.

Normally, there is a chain of chemicals working together to pass these high-energy protons along and use the energy to make the cell fuel ATP.

A LHON gene mutation changes the shape of one of these proteins, so it is less good at doing its job.

This means that some of these high-energy protons “escapes” and creates charged particles called Reactive Oxygen Species (ROS).  These particles can damage the mitochondria even more. The “escaped” protons means that less energy is used and so the mitochondriaon makes less ATP fuel.

Some pharmaceutical companies and researchers are trying to develop drugs that get into the mitochondria and help prevent these high-energy protons from escaping.  The drugs naturally “dissolve” in the mitochondrial membrane, pick up any free protons and then deliver them to the next protein in the chain.

Examples of this approach are

Idebenone by Santhera (now marketed as Raxone)

Bendavia and Ocuvia by Stealth Biotechnologies

EPI-743 by Edison Pharmaceuticals

Gene Therapies

A different approach is to try and restore the natural mechanism damaged by the LHON Gene Mutation.

Researchers developo an isolated copy of the normal mitochondrial gene, such as the ND1 gene which is affected by the 11778 LHON mutation.  The gene without the LHON mutation is called the “wild” type of the gene by researchers.

They combine this gene with a special chemical marker and package it into the coating of a virus.

The virus is injected into the eye of an affected person as soon as possible after the onset of symptoms.

The virus attaches itself to the cells of the retina and delivers its contents into the cell. (A major part of developing a Gene Therapy is proving that this step safely delivers the gene to the cells that need it).

The DNA delivered by the virus triggers the cell’s own protein “factory” to make correct copies of the mitochondrial protein, and the added marker chemical tells the cell to deliver the new protein to the mitochondria where it is needed.

The mitochondria in the cell now have the “correct” version of the protein they need, and the proton-processing chain of chemicals works normally.

A down-side of this approach is that a virus is so small it cannot hold all of the genes used by mitochondria. It can only hold one gene at a time. That means a virus developed to deliver a working ND1 gene will have no effect on someone with the 3460 mutation or the 14484 mutation, as they are in different genes for different proteins.

There are at least two places in the world working on gene therapies for LHON.

Gensight in France are working on GS010 (to correct the 11778 mutation) and in the future will start developing GS011 (to correct the 3460 mutation).

Bascom-Palmer in Florida are also working on a virus to deliver a working copy of the 11778 mutation.

Regenerative Therapy

Unlike the other therapies, the main aim of Regenerative Therapy for Leber Hereditary Optic Neuropathy would be to repair and/or replace the damaged retina and optic nerve tissue.

the major breakthrough in regenerative medicine has been the work on Stem Cells.  Many researchers around the world are studying Stem Cells and their possible use in repairing or replacing lost tissues.

At the moment Stem Cell research for eye disorders is concentrating on replacing the light detecting layer and needs the patient to have a healthy set of Retinal Ganglia Cells and optic nerve.

However, this research is making good progress in proving the techniques of stem cell therapies in the eye.

Some scientists doing basic research have shown that repairing the optic nerve may be a future possibility.

As of 2015 a major issue in Regenerative medicine is the clinics around the world offering unproven or even bogus treatments  At present treatments to repair or replace Retinal Ganglion Cells, or to repair a damaged optic Nerve, are still several years away.

 

This page was last updated August 12 2015

 

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