Drug manufacturer Novo Nordisk says semaglutide, the active ingredient in the weight-loss drug Vegovi, does not slow the progression of Alzheimer's disease, despite initial hopes it could help fight dementia.
Researchers launched two large studies involving more than 3,800 people following reports that the drug was having a real-world impact.
But research has shown that the GLP-1 drug, which is already used to treat type 2 diabetes and obesity, has no effect compared to the dummy drug.
The disappointing results are due to be presented at an Alzheimer's disease conference next month and have not yet been published in a peer-reviewed journal.
Dr Susan Kohlhaas, from Alzheimer's Research UK, said the findings would be a blow to people with Alzheimer's disease.
Martin Holst Lange, chief scientific officer and executive vice president of research and development at Novo Nordisk, said: “Based on the significant unmet need for the treatment of Alzheimer's disease, as well as a number of compelling data, we felt we had a responsibility to explore the potential of semaglutide, despite the low likelihood of success.
“Although semaglutide has not demonstrated effectiveness in slowing the progression of Alzheimer's disease, the large body of evidence supporting semaglutide continues to benefit people with type 2 diabetes, obesity and related comorbidities,” he said.
Patients in the Evoke studies ranged in age from 55 to 85 years and had mild cognitive impairment or mild dementia due to Alzheimer's disease.
The progression of dementia was tracked and measured using tests and interviews.
Treatment with semaglutide led to improvements in biomarkers associated with Alzheimer's disease, but it did not delay disease progression.
Dr Kohlhaas said: “The results of these studies are another reminder that Alzheimer's disease is caused by several different biological processes. No single approach will likely be sufficient.
“The field now needs to focus on understanding these processes in more detail and developing treatments that can be used together to combat the disease from different perspectives.”
She added that the growing use of GLP-1 drugs on private prescription, mainly for weight loss, provides an opportunity to collect better real-world data on their long-term effects.
Fiona Carragher, chief policy and research officer at the Alzheimer's Society, said that while it was “very disappointing” that these long-awaited results were not what everyone had hoped for, “no trial is wasted.”
“Every investigation helps us develop better medicines and conduct better trials in the future.”
She said there are currently more than 130 Alzheimer's drugs in clinical trials, of which about 30 are in late-stage trials, the final stage before they are reviewed by regulators.
