The UK's drugs regulator - the MHRA - has approved the Alzheimer's drug donanemab, but it won't be available on the NHS.
Author
- Rahul Sidhu
PhD Candidate, Neuroscience, University of Sheffield
The National Institute for Health and Care Excellence (Nice), which determines what treatments are available on the NHS, decided not to recommend donanemab for NHS use. This is because of its cost, potential side-effects and what some consider insufficient benefits.
While Nice's decision is disappointing for a lot of people (about 70,000 people people in England would have qualified to receive the drug), it's important to know why the decision was made.
Slowing decline
A key characteristic of Alzheimer's disease is the presence of amyloid plaques. These are sticky proteins that clump together and destroy brain cells (neurons), resulting in Alzheimer's .
Donanemab is a monoclonal antibody - a lab-made protein that targets and binds to amyloid to help eliminate it . This treatment is administered by an intravenous infusion, so the drug is delivered directly into the bloodstream. Each session lasts about 30 minutes and is needed every four weeks.
In a clinical trial , donanemab was shown to be reasonably successful. The trial compared participants with early Alzheimer's disease taking donanemab against those taking a placebo.
Donanemab slowed the decline in memory and thinking by as much as 35% in people in the early stages of Alzheimer's disease. This is the equivalent of reducing the disease's progression by four to seven months . Participants taking donanemab experienced a 40% slower decline in their ability to perform daily tasks, including managing finances, driving and enjoying hobbies.
While these results are promising, it's important to note that the clinical trial had some limitations.
The trial lasted only 18 months, so it remains unclear how donanemab's effects will play out long-term for those using it. Future studies will be needed to explore the long-term effects.
Although the trial had a large sample size of 1,736 participants with early Alzheimer's disease, 90% of the participants were white. More diversity in clinical trials is needed to ensure that donanemab is effective for people of all races and ethnic backgrounds. Unfortunately, this lack of diversity is a common issue in medical research.
But the major drawback with donanemab was its side-effects. About 80% of the side-effects participants experienced were either mild or participants showed no symptoms at all and side-effects were only picked up in further tests.
However, 15% of participants had a serious side-effect. This included brain swelling or small brain bleeds known as amyloid-related imaging abnormalities . This may initially cause mild symptoms such as headaches, confusion or dizziness. But without constant monitoring, these conditions can become detrimental to health.
There were three deaths believed to be linked to this brain swelling among the 853 participants who were administered the drug.
Another concern in using the drug relates to the existing difficulties with diagnosis. To even qualify for the treatment, patients must be in the very early stages of Alzheimer's disease - and already have confirmed high amyloid levels through a PET scan or lumbar puncture .
In the UK, only 2% of dementia patients receive these gold-standard diagnoses. More than one-third of people living with dementia don't receive a diagnosis at all.
Improved and more accessible diagnostic methods would ensure more patients are eligible to receive the drug at the optimal time.
But the key reason donanemab isn't available through the NHS is its cost. The treatment is estimated to cost around £25,000 a year per patient, based on the US cost . This does not include the expense of brain scans to monitor its effects.
Additionally, it requires monthly infusions at the hospital and careful monitoring for side-effects, which may seem excessive considering the treatment's modest benefits.
The future for Alzheimer's treatments
Nice's decision on donanemab closely mirrors the decision they made about lecanemab in August 2024. This was the first ever Alzheimer's slowing drug approved by the MHRA, and, like donanemab, is only available via private healthcare. The reasons both drugs were rejected by the Nice and the NHS are similar - with costs and side-effects being the main concerns.
While people with dementia and their families may feel let down by this decision, the fact that these new therapies can slow the disease, even slightly, offers hope.
Nice will be reassessing donanemab in 2025. There are also over 100 drugs currently in clinical trials for treating Alzheimer's. Hopefully, one of these will prove to be as effective, if not more effective, as donanemab but with fewer side-effects and at a lower cost.
Still, it's a remarkable step that there are two drugs licensed in the UK for treating Alzheimer's. Although there's still a way to go before an NHS treatment is readily available.
Rahul Sidhu does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
