Gene therapy is rarely straightforward mutation correction. The prevalent approach relies on a much simpler procedure of adding just more genes using viral vectors. That is also the case for a novel clinical trial involving patients with Alzheimer’s disease.
We know a lot about genes directly associated with this condition. One of the top success stories in DNA testing deals with variants of APOE gene, which predict the risk of Alzheimer’s disease.
People with the most severe APOE variant (E4) are diagnosed with Alzheimer’s at a mean age 68 years – in striking contrast to a mean 84 years of individuals with other variants (E3, E2) [source].
What’s more, E2 variants have been experimentally found to protect its owners from some Alzheimer’s symptoms. Few years ago those observations brought us to a proposition of adding APOE genes in E2 form to, literally, brain.
The idea was successfully tested on mice and primates. Now it progresses into humans (15 participants, details in clinical trial registry). However, we are far from curing or even stopping Alzheimer’s disease: the only goal is safety of dosing in humans, and the results are expected in 2021. Trials assessing medical outcomes are not going to be ready anywhere in the near future.