The past year has been a difficult one for the developers of potential new treatments for Alzheimer’s disease. First, the trial of a promising new drug was suddenly halted because it was not showing the hoped-for results, but then the drug’s developer announced that the results weren’t so bad after all and that they would continue to seek FDA approval for its use.
Then, two more similar drugs were found by a study to have no apparent effect on the disease’s symptoms. Despite these disappointing developments in Alzheimer’s research, the scientists involved have remained hopeful, and their work toward finding an effective treatment for the disease continues.
Pursuing the Mysteries of Amyloid
All of the drugs in question target amyloid, a protein at the root of Alzheimer’s symptoms. In the brains of Alzheimer’s patients, amyloid forms hard plaques that interfere with the function of brain cells and eventually cause irreversible cell damage and cell death. The drugs are designed to remove amyloid and, in theory, slow or even prevent the degeneration of brain tissue seen in Alzheimer’s patients.
To test the drugs’ effects, long-term studies recruited people with a rare genetic mutation that virtually guaranteed that they would develop Alzheimer’s disease. This allowed researchers to give the drugs to people who did not yet have full-blown symptoms of the disease but who would if left untreated, almost certainly show symptoms in time. If the drugs worked, they should be able to prevent symptoms from developing.
In March 2019, pharmaceutical company Biogen announced that it was halting trials on its amyloid-targeting drug aducanumab because the drug was unlikely to show positive results. In October, however, Biogen reversed course and said that after re-evaluating the results of aducanumab studies, they’d be pushing ahead to seek FDA approval for the drug.
In February 2020, the results of a study involving two more amyloid-targeting drugs, solanezumab, and gantenerumab, were released, and the news wasn’t good. Neither drug appeared to prevent declines in memory or cognitive function in the study’s participants. It wasn’t the first failure for gantenerumab, which had already had a failed trial in 2015.
Pharmaceutical Companies Stay On Course
Despite the disappointing study results, drug developers remain confident that they’re on the right track in the pursuit of amyloid. Other studies of solanezumab are underway, and Biogen intends to press for approval of aducanumab as soon as possible, maybe even before the end of 2020. In addition, Biogen is moving forward with another new drug, BAN2401, which also targets amyloid.
Skeptics are less optimistic. Some scientists point to the multiple failed trials of amyloid-targeting drugs as evidence that simply removing the protein may not be the key to effective Alzheimer’s treatments. Perhaps the mechanism of the disease in the brain is more complex than has been assumed, they say, and resources might be put to better use in the pursuit of new, different types of treatments. For now, however, the focus of drug makers remains on amyloid.
Associated Press, Drugs fail to slow decline in inherited Alzheimer’s disease
New York Times, An Alzheimer’s Treatment Fails: ‘We Don’t Have Anything Now’
Being Patient, New Alzheimer’s Trial Aims to Defeat Amyloid Before Symptoms Develop
Being Patient, Biogen Ends Late-Stage Alzheimer’s Trials, Crushing Hopes and Calling Amyloid Into Question
USC, Alzheimer’s study aims to see if the drug can block brain plaques linked to disease
BioPharma-Reporter, Biogen prepares to step up manufacturing to support Alzheimer’s launch
Endpoints, Roche is bringing back gantenerumab from the dead, taking another stab at Alzheimer’s PhIII