Research Strategies
There are 3 main areas where research for treating RP has been focused. Gene therapy, cell therapy (which sometimes called stem cell therapy) and prosthetics. These areas have been getting the most attnetion in clinical trials. It is important to note that none of these are cures and also with one exception none of these have been approved by the FDA.Gene Therapies
The treatment option that has received the most attention have been gene therapies. Scientific advances have deepened the general understanding of the genetic makeup on humans. This has led to a number of options in treating RP which is a genetic disease.
Gene editing is one of the techniques being used. This technique seeks to edit the mutated gene, thus repairing the mutation.
A similar technique is gene replacing which seeks to replace the mutated gene with a copy of the gene that does not have the mutation. In both editing and replacement the specific gene that causes RP. These are referred to as gene specific therapies. Each therapy has to be specifically created to deal with a specific type of gene. Once created these therapies are delivered using a virus that is injected into the eye. The virus changes genes in the cells in the eye to either replace the gene or edit it.
A third form of genetic therapy is referred to as gene agnostic. This means the treatment is not gene specific and therefore has a broader number of potential patients. With this treatment cells in the retina that are not photoreceptors are in effect changed to act as photoreceptors. This is delivered the same way as the other therapies, that is through a virus that targets the none phtoreceptor cells into photoreceptors.None of these treatments are a cure. The editing and replacements therapies can slow or even temporarily stop the progression of RP. In some cases some vision is restored but it is a small amount. With the 3rd option, some vision is restored but that vision is usually the central vision. It does not stop the progression of the disease.
One of these treatments have been approved by the FDA. It is called Luxterna and is specifically targeted for the RPE65 gene. It has been shown to restore some vision as well as arrest the progression of the disease.
Stem Cell Therapy
Cell therapy which is also referred to as stem cell therapy uses stem cells from the body to create photoreceptor cells that are implanted in the retina. The stem cells are created from skin cells in a patient and are then cultivated in a lab to create photoreceptor cells. These are then injected into the eye to replace the damaged photoreceptors in the patient. This therapy is in the early stages of clinical trials. However a similar technique has been used to treat some forms of cancer for a few years now. If successful the treatment would possibly restore some vision or slow down the progression of RP.Prosthetics
Prosthetic retinas which are sometimes called the chip, have been around a while. They consist of a small microchip with an array of sensors. This is implanted in the retina. The patient then wears a pair of glasses that have a video camera in it. The glasses send the image to the chip which in turn creates the electrical pulses that are sent to the brain. As technology has improved the images that are created by the chip have also improved. However they are not as good as a what the retina can do. The chips are usually used on people who have lost all vision.Other Research
There is an ongoing clinical trial investigating whether a supplement called NAC can slow down or even slightly improve vision in RP patients. NAC which is short for N-acetyl cysteine, is being investigated for possibly improving the function of the Cone photoreceptors in the retina. It may also slow down the progression of RP.
Another area of research that is in its infancy is that of eye transplants. A donor eye would be transplanted into a patient to replace the damaged eye. This would, if it eventually works, allow those with a variety of vision issues to be treated.
Clinical Trials
Clinical trials are conducted in order to seek FDA approval for a medication or procedure to treat a disease or condition. There are usually 4 phases to a clinical trial.
Phase I measures whether the drug or procedure is safe. That is, will it harm anyone who takes it. This phase usually only has a small number of participants and is only done to measure the safety of the drug/procedure.
Phase II is designed to see if the drug or procedure works for the purpose it was designed to do. It’s also designed to investigate any side effects that might occur through taking the drug or procedure.
Phase III is designed to confirm if the drug or procedure works. This is done with a blind study where some of the participants are given a placebo or sham drug or procedure.
Phase IV is designed to determine any long term effects of the drug or procedure. RP is referred to as an orphan disease in that relatively speaking so few people have it that clinical trial is given special consideration. Usually this means combining the phases as well as lowering the number of participants. Also depending on the conclusions after phase III, FDA approval can be given without phase IV. It is important to note that most clinical trials do not lead to an approved treatment. However as of late, RP and other inherited retinal diseases have seen an uptick in the number of clinical trials targeting treatments. The clinical trials currently available can be tracked on the US Government website www.clinicaltrials.gov. You should always seek advice from your retina specialist before enrolling in a trial. Further you should never ever pay to be part of a trial. Any group running a trial that is legit will never ask you for money.