Alzheimer's disease drug development seems like the Bermuda for clinical-trial—over an hundred and twenty clinical trials have sunk like a stone in the past two decades. A handful of approved drugs can only temporarily alleviate symptoms of the disease (such as loss of memory). There is no drugs that can block the disease process.
However, there is a good news from the Alzheimer’s Association International Conference in Washington DC : two high-profile clinical trials have got an exciting result.
The brain amyloid-β protein accumulation is one of the main characteristics of Alzheimer's disease. Lilly's solanezumab and Biogen's aducanumab are two for the amyloid-β antibody drugs.
According to reports, these two drugs in clinical trials successfully slowed the decline of cognitive ability, reducing the amyloid-β levels in the brain. "This shows that the targeting amyloid-β therapy is very promising," said Dennis Selkoe, the neurologist from Harvard University, a strong supporter of amyloid-β theory.
In fact, Lilly, of Indianapolis, Indiana, had launched a 18-month clinical trial of solanezumab in 2012. The conclusion was that the use of solanezumab did not seem much different with placebo. But when the researchers re-examine the clinical data, they found that there are slight improvements of patients with mild Alzheimer's disease after using solanezumab. So Lilly continues to drug testing.
New research shows that in 440 patients with mild Alzheimer's disease, solanezumab slows the cognitive decline by 30%. The researchers also note that the drug has reached the root of Alzheimer's disease, and not just relieves their symptoms.
Biogen's report noted that regular doses of aducanumab has reduced the brain amyloid-β protein level in the 23 patients. Although the improvement condition of patients in the clinical trials is not clear, their previous studies have shown that high doses aducanumab can significantly relieve the patient's cognitive decline in patients in a year, with brain amyloid-β also relatively small.
Amyloid plaques: chicken or the egg?
Both two studies provide a strong support for the "amyloid hypothesis". This theory holds that the brain of amyloid accumulation is the cause of Alzheimer's disease, and they can be removed to prevent development of the disease. "We’re creeping in the right direction," said Samuel Gandy, a neurologist at Mount Sinai School of Medicine in New York, “A lot of the euphoria is because things were so negative for so long.”
However, the size of these clinical trials is still relatively small. Lilly launched a larger phase III trial of solanezumab in 2013, involving 2,100 patients with mild Alzheimer's disease. The study will be end in October 2016. In December this year, Biogen said that it would launch a phase III trial with 2,700 participants, for a period of 18 months.
Source: Nature: Antibody drugs for Alzheimer’s show glimmers of promise, on July 22, 2015.