Biogen shares dipped slightly Monday morning after two peers released negative results for experimental Alzheimer's drugs, suggesting investors remain sensitive to news that could be seen as a threat to the future of the biotech's own treatment.
The negative results come from a study called DIAN-TU, which tested whether drugs from Eli Lilly and Roche could prevent Alzheimer's from developing in patients genetically predisposed to the disease. Both drugs target amyloid beta, a protein that's been at the center of Alzheimer's research efforts for years.
Amyloid-targeting drugs, including the two under investigation in DIAN-TU, have failed before in clinical testing. A common defense of supporters of the amyloid hypothesis is that drugs aren't being tested in the right patients or early enough in the disease's development. Preventive trials with well-defined patient groups, such as DIAN-TU, could therefore have provided support to that line of thinking.
However, Lilly and Roche said neither of their drugs showed a significant benefit over placebo in patients with an early-onset, inherited form of Alzheimer’s disease, who were evaluated using a series of cognitive tests. Research indicates this type of Alzheimer's accounts for less than 1% of all cases.
Biogen has said it intends to submit aducanumab, one of its amyloid-targeting Alzheimer's drugs, for approval sometime early this year. Pointing to differences in patient population, sample sizes, study endpoints and other factors, the company cautioned against directly comparing DIAN-TU with the Phase 3 aducanumab studies on which it's approval application hinges.
"While any setback in Alzheimer’s disease trials is unfortunate, it does not change our commitment to advancing aducanumab and the rest of our pipeline of potential Alzheimer’s therapies," Biogen said in an emailed statement.
Analysts, meanwhile, continue to speculate about what a miss in DIAN-TU means for Biogen — namely, whether it will weigh on the minds of regulators reviewing aducanumab.
In late January, the team at Jefferies wrote how they would expect Biogen's stock to decline around 5% if DIAN-TU had a negative readout, as it would provide evidence that amyloid studies "just aren't working" and that the Phase 3 data Biogen tout as positive are "just an artifact of luck."
"In our minds it is at least somewhat relevant," Stifel analysts wrote of the DIAN-TU readout in a Monday investor note, adding that patients enrolled in the study were "supposed to be genetically and biologically enriched for an amyloid-based drug strategy."
Even so, Wall Street is holding off on making concrete predictions about the trial's broader effects.
"The precise implications of the study's findings with respect to either the amyloid hypothesis or to aducanumab's chances at the FDA aren't yet clear," wrote the Stifel analysts.
Biogen shares appeared to reflect the ambiguity. They were down 2% in premarket trading, but ticked up once markets opened to sit at roughly 1% in the red.
Lilly said that, based on the results, the company doesn't intend to submit an approval application for its drug in this patient population. Roche said it will continue to evaluate both the DIAN-TU data as well as data from its GRADUATE program, which comprises two large, Phase 3 studies that are enrolling a broader selection of Alzheimer's patients whose disease isn't directly caused by gene mutations.
"This outcome does not reduce our confidence in the ongoing Phase 3 GRADUATE clinical programme," Roche said in a Feb. 10 statement.
Lilly shares were down 3.5% at market's open Monday. Roche shares, which trade on the Swiss stock exchange, were essentially unmoved.