Huntington’s disease has long been a scourge of the medical community. Huntington’s is a neurodegenerative disease that has no known cure or even treatment. That may change soon, thanks to a new breakthrough that could lead to a drug treatment to prevent the onset of Huntington’s. This is a landmark event in the treatment of Huntington’s, being one of the biggest advancements in the past 50 years.
What Is Huntington’s Disease?
Huntington’s disease is a neurodegenerative disease, and it impacts almost every function of the body. Over time people with Huntington’s will have difficulty thinking, speaking, walking, and swallowing. The condition is usually fatal and the condition afflicts approximately 1 in every 10,000 people or about 30,000 people overall. The National Institute of Neurological Disorders and Strokes predicts that another 150,000 people are at risk of developing the disease.
“For some people, it’s best for their mental health to know they have the gene for Huntington’s and some time in the future they’ll have a problem. But to other people, it would be a disaster.” — Leroy Hood
The disease is inherited by people, and it is caused by faulty genes in a person’s DNA. People who have the gene for Huntington’s disease have a 50% chance of passing the disease onto their children. The gene for Huntington’s disease can be tested for, and the symptoms of Huntington’s can take years to show themselves, though at some point symptoms will manifest. For a long time, the progression of Huntington’s disease could not be prevented, though new research done by scientists at University College London (UCL) could lead to an effective treatment for the disease.
Suppressing The Build-Up Of Proteins
The research team from UCL has discovered a treatment that is capable of suppressing the toxic proteins that build up in the brain of those with Huntington’s disease. The buildup of these proteins is caused by a faulty gene on chromosome 4, the mhTT gene. The drug functions by disrupting the expression of this gene, meaning that the protein called huntingtin doesn’t build up as much, which should ideally slow the rate at which the disease progresses.
“As far as regenerating parts of the brain that have degenerated, such as in Parkinson’s disease, Huntington’s disease, and others of that nature, the ability to regenerate the needed cell and placing it in the correct spot would have major impact.” — Eric Holland
The drug is referred to as IONIS-HTTRx, and it binds to the messenger RNA which triggers the production of huntingtin in the brain. The drug is able to take apart the messenger RNA before it can produce the damaged proteins. The research team reports that the drug was able to substantially reduce levels of the huntingtin protein in the brain during a trial of the drug.
A clinical trial was done on the drug, which had 46 different patients who had the drug injected into their spinal fluid. Not only did the participants who received the drug showed less huntingtin in their brains, but there also didn’t appear to be any harmful side effects associated with the drug.
It should be noted that the trial didn’t look for whether or not the drug stopped the progression of the disease, it just measured the levels of toxic proteins in the brain. So while the researchers can’t definitively say that the medicine worked to prevent the onset of Huntington’s the results are encouraging. Sarah Tabrizi, who led the research team from UCL, says that they want to move on to doing larger-scale trials and testing whether the drug can meaningfully slow the progression of the disease.
Analysts of drug treatments and biomedical science have called the new drug “game-changer”, saying that the new drug has profound implications for genomic medicine in general, not just the treatment of Huntington’s disease.
Dr. Philippa Brice from the think-tank PHG Foundation says that while more research must be done the drug offers a glimpse into the possibilities of gene-silencing based treatments.
“…We could be on the brink of some of the personalized treatments that patients with severe genetic diseases need so badly.”
Brice notes that there will be many questions that arise regarding how best to implement gene-silencing based treatments and that policy-makers and society will have to grapple with them.
Future Applications For The Drug
Nancy Wexler, who originally identified the mutation responsible for Huntington’s in 1993, says she’s “ecstatic” about the discovery. A previous study done by Wexler was key to identifying the gene. Wexler and her team went to Venezuela where she conducted rigorous research and identified 18,149 individuals with Huntington’s disease. These subjects spanned 10 generations, and the study went on for four decades. Wexler is excited about the discovery because it means that for the first time it is possible to give those diagnosed with Huntington’s disease some kind of hope.
“Anyone who wants to pretend that your Huntington’s disease is an invention is someone who does not have your best interests at heart.” — Mallory Ortberg
The dream of the research team is that the drug may even make reversing the damage done by the disease possible. Similar studies done on animals have found that halting the production of the mutant protein actually allows the brain to begin healing itself. It doesn’t just halt the progression of the disease.
There is some speculation that the drug could be the basis for the treatment of other neurodegenerative diseases like Alzheimer’s. Other neurodegenerative diseases are also characterized by the buildup of toxic proteins within the brain. Parkinson’s disease sees the protein synuclein building up, while the proteins tau and amyloid are connected with various forms of dementia. Some scientists, like Giovanna Mallucci of the UK Dementia Research Institute, have argued that it’s a long-shot to expect gene-silencing drugs to simply be applied to the treatment of other neurodegenerative diseases.
Mallucci argues that the cause of these diseases is less-understood than Huntington’s disease, so it may be a while before the research that would allow these diseases to be tackled with gene-silencing comes to fruition. That said, in principle, any gene which affects disease progression and susceptibility can be modified, so continuing to pursue research down these roads is very important.
Ionis Pharmaceuticals is the company responsible for producing the drug and licensed IONIS-HTTRx to pharmaceutical company Roche. The results of the study will formally be presented at a conference and published in a peer-reviewed journal next year. While more research into the drug will have to be done, the work done by the UCL team represents both a major breakthrough in the treatment of the disease and hope for those afflicted with it.