By Emma Court
An experimental drug from drugmakers Biogen and Eisai emerged this summer with the potential to do what no other medication has been able to: slow the development of Alzheimer’s disease, a progressive and devastating disease marked by cognitive decline.
But a major question — whether differences in genetic risk for the disease explain away the late July results — has hung over the drug, called BAN2401.
With new study results, presented by the two companies early Thursday at a European conference, the uncertainty lingers on, even as it has become more complicated.
Biogen shares /zigman2/quotes/201531540/composite BIIB -1.78% dropped more than 3% in heavy Thursday trade before evening out to a 1.2% decline, while Eisai shares dropped 5.7% /zigman2/quotes/203064480/delayed JP:4523 +13.74% . Biogen shares also declined the day before the BAN2401 results, and dropped 1.8% in Friday premarket trade.
BAN2401 only appeared to slow the decline of patients with a genetic risk factor called ApoE4, Leerink analyst Geoffrey Porges noted, but even there, follow-up numbers, for just 10 patients, were of limited usefulness. He described the trial results as “thin, unconvincing.”
”In our view this data is confusing, suggesting only limited value for BAN2401 in the carrier population, while the small number of patients remaining on drug at the 18-month time point and lack of clear dose responses diminish the reliability of this dataset,” Porges said.
BAN2401 targets beta-amyloid proteins in the brain that are believed to play a role in Alzheimer’s disease, working to “neutralize and eliminate” them. Removing the protein fragments should slow the disease’s progression, the thinking goes.
BAN2401 is one of two promising Alzheimer’s disease drugs from Biogen, and both target beta-amyloid.
Increasingly, though, experts have begun to think that other proteins that accumulate in the brain may also play a role alongside beta-amyloid. BAN2401’s results have only added fuel to that fire.
The small number of patients in BAN2401’s high-dose group dates back to 2014, when a “request from a health authority” limited the trial’s enrollment, the companies said.
If anything, the small enrollment could mean that the drug is even more effective than previously found, scientists from Eisai and elsewhere said during the Thursday presentation.
But that’s debatable, said Stifel analyst Paul Matteis, since “the small sample size limits our conviction in drawing any sort of firm conclusion.”
“The irony however is that clinical data in APOE4+ non-carriers (a bigger sample) look underwhelming,” he said, “raising new unanswerable questions.”
Biogen shares have dropped 13.4% over the last three months, compared with a 4.7% drop in the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.27% and a 2.1% decline in the Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA +1.30% .