A day after the drug company Biogen reported promising results on an experimental Alzheimer’s drug, experts were optimistic that researchers may be turning the corner on the mind-robbing disease after years of failure.
Cambridge, Mass-based Biogen and Tokyo-based Eisai Co. this week released data from a medical study that showed their experimental drug, taken at high doses, removed a brain protein found in Alzheimer's patients and slowed memory and thinking problems of people in early stages of the disease.
But investors questioned Thursday whether the drug, called BAN2401, has the potential to develop into a blockbuster medication. The stock prices of both pharmaceutical companies tumbled after study details were released Wednesday at the Alzheimer's Association International conference in Chicago.
"The design and statistics were so complicated, it makes it very difficult to interpret the clinical consequences of treatment," said Pierre Tariot, a psychiatrist and director of Banner Alzheimer's Institute in Phoenix.
The results of the drug trial were encouraging but were "not definitive by any means," Tariot said.
Patients who took the highest doses of the experimental drug twice a month via IV had the most significant reduction of beta amyloid, a protein that accumulates in the brains of Alzheimer's patients. These patients treated with the highest doses had a 30 percent reduction of "clinical decline" based on a test when compared with people who received a placebo.
However, those results were among patients who received 18 months of treatment, a secondary measure, not the 12-month measure that represented the study's primary goal.
Still, Tariot said the study was a "boost for the field" because it was the second Alzheimer's drug that linked the reduction of beta amyloid and mental decline. The other drug, aducanumab, also developed by Biogen, is being tested in later-stage clinical trials.
Pharmaceutical companies have invested billions of dollars on failed drugs that target amyloid, which is thought to cause the disease by accumulating in the brain and disrupting communication between brain cells and killing them.
But drugs that target amyloid have failed to slow mental decline.
A string of clinical trial failures prompted many to question whether drug companies were on the right track.
"People were ready to say the amyloid theory was dead," said Marwan Sabbagh, a geriatric neurologist and director of the Cleveland Clinic Lou Ruvo Center for Brain Health in Las Vegas. "This says strongly, with an exclamation point, that is not true."
Some believe that the key is starting treatment early, even before memory and thinking problems emerge.
Banner Alzheimer's Institute is testing anti-amyloid drugs on people who face high genetic risk but no symptoms. Those studies – one involving an extended family in Colombia and a second involving healthy older adults who carry a high genetic risk of developing Alzheimer’s disease – are testing drugs on patients before memory and thinking problems occur.
The Colombian clinical trial will study an anti-amyloid drug, crenezumab, on an extended family whose members carry a rare genetic mutation that guarantees they will get Alzheimer’s disease, usually beginning in their mid-40s.
Preliminary data released by researchers this week showed that more than 40 percent of the Colombian family members had no signs of amyloid protein in the brain at the start of the study. Because of that, Tariot said the study will test the very idea that a drug – if administered early enough – can prevent the onset of disease.
"This will be the first trial" that tests that theory, he said.
