A drug which appears to reverse Huntington's disease is being trialled in humans after it was found effective and safe when tested in mice and monkeys, scientists say.
The drug called IONIS-HTTRx acts as a 'gene silencer' to inhibit the production of huntingtin protein in people with Huntington's disease.
Huntington's disease is a rare, hereditary ailment that causes uncontrolled movements, loss of intellectual abilities, emotional problems and eventually leads to death.
The disease is passed from parent to child through a mutation in the huntingtin gene. The mutation results in the production of a disease-causing huntingtin protein.
"It is very exciting to have the possibility of a treatment that could alter the course of this devastating disease," said Blair R Leavitt from the University of British Columbia in Canada.
"Right now we only have treatments that work on the symptoms of the disease," Leavitt said.
Each child has a fifty-fifty chance of inheriting the gene mutation. Everyone who inherits the mutated gene will eventually develop the disease.
Earlier studies in mouse models of Huntington's disease showed that treatment with antisense drugs delayed the disease progression and resulted in sustained reversal of its phenotype.
In YAC128 mice, a transgenic model of HD, motor deficits improved within one month of initiating antisense treatment and were restored to normal at two months after treatment termination.
Motor skills of antisense-treated BACHD mice, another transgenic model of HD, improved eight weeks after initiation of treatment and persisted for at least nine months after its termination.
In monkeys, dose-dependent reductions in HTT mRNA and Htt protein throughout the central nervous system were observed after intrathecal administration of an antisense drug.
Reduction of cortical huntingtin levels by 50 per cent was readily achieved in monkeys and correlated with 15 to 20 per cent reduction in the caudate.
In further tests in rodents and monkeys, IONIS-HTTRx was found to be well-tolerated without any dose-limiting side effects.
