A first-of-its-kind Alzheimer’s drug that slows cognitive decline in early-stage patients, that was developed using animal research, has now been licensed for use around the world, including China, Japan, USA and most recently in the UK.

Lecanemab is the first Alzheimer’s drug that directly targets aspects of the disease itself, rather than just the symptoms. It works by removing an abnormal build-up of beta-amyloid proteins in the brain, which have been implicated in Alzheimer's.

The drug, an antibody derived from mice, highlights the long-standing role of animal research in its development and approval.

Before being tested in humans, studies in mice showed that lecanemab could work by reaching the brain, specifically binding to beta-amyloid and successfully protecting neurons.

As a humanised mouse antibody – that is made to be more ‘human-like’ so it does not trigger an immune reaction in people – lecanemab can recognise and bind to the amyloid proteins in human patients.

One clinical trial showed that it reduced beta-amyloid levels and slowed cognitive decline by 27%.

It was also originally thanks to studying genetically modified mice, that researchers first understood the toxic effect that beta-amyloid can have in Alzheimer’s disease.

The UK Alzheimer’s Society said in a recent statement that the drug approval was 'a defining moment for people with early-stage Alzheimer’s disease in the UK and a significant step towards a more hopeful future'.

Using 3D brain organoids, researchers have linked a gene with Huntington’s disease for the first time, which may provide a new target for treatment.

Huntington’s is an incurable neurodegenerative disorder that affects movement, thinking ability and mental health. It is caused by mutations in the HTT gene, which leads to the progressive death of nerve cells in the brain.

In the study, led by EARA member the Max Delbrück Center, Berlin, and Heinrich Heine University (HHU), Dusseldorf, both in Germany, researchers used CRISPR-Cas9 gene editing to make genetic changes to healthy human stem cells, resembling the HTT mutations seen in Huntington’s.

As stem cells are able to develop into any type of cell, the edited stem cells could then be grown into brain organoids that resemble aspects of the early-stage brain.

Analysing the organoids at different developmental stages showed there were lower levels of a particular gene (CHCHD2), which hampered how the nerve cells carried out vital chemical reactions in the brain.

Selene Lickfett, at HHU, discussed whether this effect could be reversed by restoring CHCHD2: “It suggests in principle that this gene could be a target for future therapies.

“The organoid model suggests that HTT mutations damage brain development even before clinical symptoms appear.”