The results of the first trial are "a triumph" for Huntington's patients and their families since existing medications only help to manage the symptoms of the disease, one of the researchers told DW.
Scientists at the University College London (UCL) on Monday announced that for the first time a drug has been used to successfully lower the level of a protein known to cause Huntington's disease in the nervous system of patients.
"We were pleasantly surprised by the results," Dr. Edward Wild, a senior investigator on the UCL drug trial, told DW.
The Ionis Pharmaceuticals drug IONIS-HTTRx managed to reduce the level of the mutant huntingtin protein during the trial and researchers were excited to discover that these reductions were "dose-dependent."
"In other words, the bigger the dose of the drug that was given, the bigger the reduction in the huntingtin protein level," Wild explained. "So that really was a home run for this trial."
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Professor Sarah Tabrizi, director of the UCL Huntington's Disease Centre, said in a statement that not only was it the first time a drug managed to lower the levels of the toxic protein, but that IONIS-HTTRx was "safe and well-tolerated."
"The results of this trial are of ground-breaking importance for Huntington's disease patients and families," Tabrizi said.
Hope for those with Huntington's
Currently, medications on the market for those with Huntington's focus solely on managing the disease's symptoms and there is no effective disease-modifying treatment for the condition.
"What's special about this drug is that it's targeting the known cause of the disease," Wild told DW.
The first human trial started in 2015 after more than a decade of pre-clinical development. A total of 46 patients with early Huntington's disease were enrolled in the trial at nine study centers in the UK, Germany and Canada.
Each patient received four doses of either IONIS-HTTRx or a placebo via injection into the spinal fluid to enable it to reach the brain. As the trial progressed, the dose of IONIS-HTTRx was increased several times according to the trial design.
Wild said he and others who worked on the trial were grateful for the years of work and coordination that built up to the trial, but that he was particularly thankful to the trial participants.
"The 46 patients in the trial did an incredibly brave thing for the betterment of the human race," he said. "Honestly it's a huge triumph of the human spirit."
Larger trial needed
The success of the trial has led Ionis Pharmaceuticals' partner Roche to exercise its option to license the product. Roche will assume responsibility for further development, regulatory activities and commercialization activities for the drug.
The UCL statement said that the safety profile of the trial supports further testing with patients.
"We have every reason to believe that if we can treat early to reduce production of the mutant protein that we should be able to produce really meaningful delays in the onset of symptoms. And if we're lucky, we may be able to prevent the disease altogether," Wild said.
The researcher noted, however, that a much larger, longer trial is needed to show that IONIS-HTTRx can slow the progression of Huntington's disease. It could take around four or five years before the drug is available on the market.
Huntington's in an inherited disorder that results in the death of brain cells. The person's physical ability declines until movement becomes difficult and they can no longer talk, while their mental ability generally deteriorates to dementia.
The onset of the disease usually begins between the ages of 30 and 50 and continually worsens over a period of 10 to 25 years.
There is currently no effective disease-modifying treatment for the condition, with existing medicines focused only on managing disease symptoms.