Scientists say they have slowed and even reversed some of the devastating and relentless decline caused by motor neurone disease (MND).
The treatment only works in 2% of patients but has been described as “really remarkable” and “a moment of real hope” for the disease as a whole.
One leading expert said this was the first time she had seen patients improve – but this was not a cure.
The MND Association said there was “increased confidence” in the therapy.
MND, also known as amyotrophic lateral sclerosis (ALS), is caused by the death of the nerves that carry messages from the brain to people’s muscles. It affects their ability to move, speak and even breathe.
The disease shortens people’s lives significantly and most die within two years of being diagnosed.
Les Wood, 68, from South Yorkshire, was the first British patient in the international trial, published in the New England Journal of Medicine.
MND forced him, an electrician, and his wife, Val, a nurse, to give up their careers, as it became more difficult to walk and use their hands.
A mutation in a specific part of its genetic code results in a toxic form of the SOD1 protein, which kills motor neurons. These mutations cause about 2% of MND cases but one in five of those run in families.
The trial on 108 people, funded by the pharmaceutical company Biogen, used an innovative type of medicine called gene silencing. The drug tofersen effectively silences the defective DNA so less SOD1 is produced.
The treatment requires monthly lumbar punctures, in which a needle is inserted between the bones in the spine to inject the drug directly into the spinal fluid.
After six months of therapy, those who received the drug had lower SOD1 levels but were not physically better.
After a year, however, the pace of the disease was slowing – and some patients’ symptoms improved.
Les had his first dose in 2016 – and in home videos recorded a year later, he said: “I could honestly say, hand on heart, I felt better.
“I actually walked in the house, without sticks, I thought, ‘This drug is working.'”
Now, he says: “MND is a progressive disease – so even though my symptoms are getting worse, I wouldn’t be without the drug and the difference I know it has made to my quality of life.”
For Professor Dame Pamela Shaw, director of the Institute of Neurology, in Sheffield, and a veteran of more than 25 clinical trials in the disease, this was something incredible.
She told me: “This is the first time the participating patients have reported an improvement in their motor function – ‘I can walk without my sticks. I can go up my garden steps, which I couldn’t do. for two years. I can write my Christmas cards this year, which I couldn’t do last year.'”
The results were a “moment of real hope” and the start of a “new era” in which we can expect progress in other forms of MND as well.
In the early stages, the researchers say, the drug is stopping further damage. It cannot lead to the formation of new motor neurons and the others may take a year to recover and form new connections with muscle tissue.
“It may take time for people to heal from the damage that has already been done,” said Dr. Timothy Miller, the lead investigator, at the University of Washington.
“The vast majority of people with ALS experience a relentlessly progressive downhill course, so stabilization of function is wonderful.”
The treatment targets the root cause of this type of MND so it will do nothing for the 98% of patients without the SOD1 mutation – although it is expected that the other mutations, in more than 30 different genes, could focus on its similar way.
“The approach used to reduce harmful MND proteins is likely to have wider applications in more common forms of MND,” said Professor Chris McDermott, from the University of Sheffield.
Tofersen is being considered for regulatory approval in the US and is being made available free of charge in the UK before a decision is made on whether the NHS should pay for it.
The MND Society’s director of research, Dr Brian Dickie, said the treatment had “the potential to be of significant benefit” to a relatively rare group of people with the disease.
The big question, he said, is whether to give the drug in the earliest stages of the disease, when it may be “more effective”, or even to healthy people with the SOD1 mutation to ” prevent the onset of disease”.
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