The UK discovery has been hailed as the “biggest breakthrough in 50 years” to treat the inherited condition which causes progressive brain damage.
Researchers at University College London (UCL) found the drug IONISHTTRx lowered levels of toxic proteins in the brain of 46 test patients.
The drug is injected into patients’ spinal fluid and “silences” the faulty “huntingtin” protein that causes Huntington’s disease.
It is believed that targeting and eliminating toxic proteins may help to treat other neurological diseases such as Alzheimer’s and Parkinson’s.
Lead researcher Professor Sarah Tabrizi said: “This is of groundbreaking importance for patients and families. I’ve been seeing patients in my clinic for nearly 20 years and many over that time died.
“For the first time we have the potential, we have the hope, of a therapy that one day may slow or prevent Huntington’s disease.”
The condition is a genetic disorder which affects the central nervous system, causing involuntary movements, difficulty with talking and memory loss.
It affects 8,500 adults in the UK with patients, on average, living between 10 and 20 years after diagnosis.
Huntington’s is caused by an “error” in a section of DNA that contains instructions for making the huntingtin protein for brain development.
UK researchers trialled the drug on 46 patients at UCL’s National Hospital for Neurology and Neurosurgery.
Peter Allen, who is on the trial and in the early stages of Huntington’s, has already lost his mother Stephanie, uncle Keith and grandmother Olive to the disease.
Tests show his sister Sandy and brother Frank will develop the disease, and their eight children have a 50 per cent chance of developing it.
The 51-year-old from Essex, said: “You end up in almost a vegetative state, it’s a horrible end. It’s so difficult to have that degenerative thing in you.
“I’m the luckiest person in the world to be sitting here on the verge of having that treatment. Hopefully it will be made available to everybody, to my brothers and sisters and fundamentally to my children.”
The complete results of the drug will be published next year.
Meanwhile, scientists at the University of Manchester have confirmed the discovery of a major cause of degenerative diseases.
As part of an international team, they found that the toxic build-up of urea, a compound created by the liver, can cause brain damage leading to dementia.
Professor Garth Cooper said: “This study is the final piece of the jigsaw which leads us to conclude that high brain urea plays a pivotal role in dementia.”