The phase 1 clinical trial involved was conducted by UCL's Huntington's Disease Centre. Professor Sarah Tabrizi, who led the trial, hailed the results as being beyond what she had ever hoped. She called the results ground-breaking for Huntington's disease patients and families. The reason the results have been described as "enormously significant" was because this is the first time a drug has slowed the disease's progression by suppressing the effects of the Huntington's mutation which causes irreversible brain damage. The existing treatments only deal with the symptoms.
About 10,000 people in the UK have Huntington's and 25,000 carry a gene that means that they potentially could develop it too. Huntington's is an incurable degenerative disease caused by an inherited gene defect. Symptoms include mood swings, anger, depression, uncontrolled movements, dementia and ultimately paralysis.
The Huntington's gene contains instructions for cells to make a toxic protein called huntingtin. A messenger molecule copies this protein and sends it to the cell's protein-making machinery. The drug in this clinical trial intercepts the messenger molecule and destroys it before the harmful protein can be made.
What excites scientists even more than the potential for the Huntington's sufferers, though, is the potential wider application. It could feasibly be adapted to halt other incurable brain disorders too, including Alzheimer's and Parkinson's.
Roche has agreed to pay Ionis Pharmaceuticals, the California-based biotech company behind the new drug, a US$45m licence fee to take the drug forward to clinical use.
Dr Philippa Brice, from biomedical sciences think-tank PHG Foundation, said: "This is a potential game-changer, not only for Huntington's disease patients but also for genomic medicine in general. Though more work needs to be done, if gene silencing lives up to this promise we could be on the brink of some of the personalised treatments that patients with severe genetic diseases need so badly."
This is very exciting, but the trial involved only 46 patients with the disease. It will now go through to a bigger trial run by Roche in the next stage. The sector will want to watch results of that stage closely to see if the very encouraging signs from the phase 1 trial will be continued.