Scientists have hailed the first drug shown to slow the destruction of the brain in Alzheimer's disease as a 'momentous' breakthrough, ending decades of failure and suggesting a new era of treatments for the most common form of dementia is possible.
The medicine, lecanemab, works by attacking sticky protein clumps called beta amyloid that build up in the brains of people with Alzheimer's. In a trial involving 1,795 volunteers with early-stage disease, those given fortnightly infusions experienced a decline in cognitive function that was slowed by about a quarter over 18 months compared with a placebo. The results, presented at the Clinical Trials on Alzheimer's Disease conference in San Francisco and published in the New England Journal of Medicine, are not a cure but have been welcomed by experts.
Prof John Hardy, one of the leading researchers behind the amyloid-targeting approach, said the findings were 'historic' and expressed optimism that 'we're seeing the beginning of Alzheimer's therapies'. Prof Tara Spires-Jones, from the University of Edinburgh, called the results 'a big deal because we've had a 100% failure rate for a long time'.
David Essam, a 78-year-old former joiner from Kent, took part in the international trial. His wife Cheryl said the trial had given the family hope, adding: 'He's not the man he was, he needs help with most things, his memory in general is almost non-existent.' David said: 'If somebody can slow it [Alzheimer's] down and eventually stop it all together that would be brilliant, it's just a horrible nasty thing.'
However, the 'real world' impact of lecanemab is debated. The slower decline was measured on an 18-point scale, with those on the drug scoring 0.45 points better. Dr Susan Kohlhaas, from Alzheimer's Research UK, described it as a 'modest effect' but one that gave 'a little bit of a foothold'. There are also risks: brain scans showed brain bleeds in 17% of participants and brain swelling in 13%, with 7% stopping the drug because of side effects.
The data is being assessed by regulators in the US, with developers Eisai and Biogen planning to seek approval in other countries next year. A crucial question remains about what happens after the 18-month trial period, and experts note that most people with early cognitive impairment would still miss out unless diagnosis is revolutionised.
