There are a number of companies that are looking at using various different drugs as a form of treatment for Stargardt's disease.
Professor Andrew Lotery, a professor of ophthalmology at the University of Southampton and consultant ophthalmologist at University Hospital Southampton NHS Foundation Trust, is the first in the UK to be trialling a pioneering drug in a £5 million study with colleagues at centres in the Netherlands, Italy, Germany and Norway. The drug remofuscin, which is taken orally, removes the fat deposits, known as lipofuscin, which build up in the back of the eye. More information can be found on https://www.southampton.ac.uk/medicine/news/2018/02/13-02-2018-andrew-lotery.page
The cause of Stargardt’s disease is faults in the ABCA4 gene. The ABCA4 gene’s role is to produce a protein called a Rim protein. The Rim protein’s role is to help transport Vitamin A molecules (needed to form the light sensitive pigment in rod and cone cells) from the photoreceptors back to RPE cells, where these Vitamin A molecules are recycled to be reused for vision.
However, in Stargardt’s, the faulty ABCA4 gene produces a Rim protein that either is non-functional or has significantly reduced function, and thereby disrupts this process of transport. The Vitamin A molecules therefore tend to accumulate in the photoreceptors/RPE cells rather than being transported and recycled. This causes a waste management problem resulting in build-up of toxic products, including ‘Vitamin A dimers’, which are believed to be involved in vision loss, by damaging RPE cells and photoreceptors.
Alkeus Pharmaceuticals have developed an oral drug called ALK-001 which aims to prevent the formation of these toxic Vitamin dimers in the retina.
They have successfully completed their safety trial and now have started Phase II of their clinical trial in adults and children (n=50) with Stargardt disease. The trial is fully enrolled and the last patient visit is anticipated in July 2019.
Acucela has started enrolling patients (November 2018) for the Phase 3 placebo controlled clinical trial for the oral drug called Emixustat which has been developed to slow the build-up of toxic waste products which are believed to be responsible for the vision loss in Stargardt disease.
Moorfields Eye Hospital will be the primary trial site in the UK.
Ophthotech is conducting a randomised, controlled clinical trial assessing the safety and efficacy of Zimura® (avacincaptad pegol), an intravitreal (injected into the vitreous gel of the eye) agent targeting the Complement inflammation system which is believed to be activated and cause damage to retinal cells following the accumulation of vitamin A-related toxic waste products.
Moorfields Eye Hospital will be the primary trial site in the UK.
Nacuity Pharmaceuticals are planning a Phase II trial with a drug called NACA which is derived from N-acetylcysteine in 2018. Phase I is on-going.
N-acetylcysteine is an antioxidant (hinders oxygen damage to the body).
N-acetylcysteine-amide (NACA) is designed to slow vision loss by protecting retinal cells from oxidative stress. Oxidative stress is a process that is thought to accelerate and exacerbate degeneration in many inherited retinal conditions.
Lin Bioscience will be conducting a Phase 1 placebo-controlled safety clinical trial.
The drug known as LBS-008, is designed to prevent the build-up of toxic waste products in the eye (lipofuscin and lipofuscin-related material), that causes damage to the retina in Stargardt's Disease.
Natural History Studies
The Foundation Fighting Blindness Clinical Research Institute has funded a $6 million multi-centre international (USA, UK, France and Germany) natural history study (ProgStar) for people affected by Stargardt's disease.
It has three primary goals:
- Determine the best outcome measures to accelerate evaluation of emerging treatments in clinical trials
- Better understand disease progression for selecting future clinical trial participants
- Identify potential participants for forthcoming clinical trials.
The natural history study uses retinal imaging and functional testing of patients with Stargardt’s disease who have been seen every six months for two years with the hope to get a better idea of the prognosis and how the disease progresses. Predominantly adults with milder Stargardt disease were recruited.
There are many published ProgStar papers. Here is a link to one of them:
Professor Michel Michaelides, who is a Professor of Ophthalmology at the UCL Institute of Ophthalmology and Consultant Ophthalmologist at Moorfields Eye Hospital, is also leading a Natural History Study (part funded by the Macular Society – UK), which is a longitudinal study over two years. More than 70 genetically confirmed patients (adults and children) with Stargardt's disease are participating and have had detailed serial structural and functional testing. The patients will be reviewed every six months for two years after an initial baseline assessment.
Systematic Review of Treatments for Dry AMD and Stargardt’s
Norman Waugh and a team of colleagues from the University of Warwick have published a systematic review of treatments for dry AMD and Stargardt’s (May 2018). They reviewed all the relevant studies in Stargardt’s and made some recommendations:
- NIHR may want to consider a trial of fenretinide to reduce damage to the macula and a pilot study of the nutritional supplements, lutein and zeaxanthin, to see if they protect the macula
- It could be useful for research studies to look for changes earlier in the diseases before vision is affected
What do Phases mean in a clinical trial?
A clinical trial is normally divided into four phases to test its safety and effectiveness.
- Phase I will test the safety of a drug, observing the side effects of it and will typically test a small number of people, usually who are healthy volunteers.
- Phase II will normally test the effectiveness of the drug on a larger group of people who have the disease, again looking at safety and if the treatment has an effect on the condition.
- Phase III will be tested on an even larger population and may involve using a placebo as well as the drug to see the effect of the treatment. The participants will not usually be aware if they have been given the placebo or the drug that is being tested.
- Phase IV is the final phase and is usually done after the treatment has been approved by the drug regulatory authorities. It will study the effect of the drug on a range of people and look at any long-term side effects.
More information can be found at:
Information about clinical trials that are currently being conducted worldwide can be found on www.clinicaltrials.gov and can be searched by condition and trial location.