Biogen, Eisai BACE drug cuts amyloid beta in the brain, but there’s no hard data to show it does anything important for cognition

Just after Merck $MRK research raised serious doubts about the BACE approach to tackling Alzheimer’s disease, researchers for Biogen $BIIB and Eisai are fighting against the tide this week. And they have a long way to go before they start persuading they may have something of value for patients.

Lynn Kramer

The team focused on the oral BACE drug elenbecestat says the drug is doing what it’s intended to do, cutting down on the amount of amyloid beta in the brains of patients with a mild form of the disease and producing a numerical decline in the rate at which patients’ cognition spirals downward.

But …. the researchers were unable to track anything in the 18-month Phase II study that qualified as a statistically significant improvement on cognition scores. Actual data were being held back, so we don’t know why exactly the team concludes that the response suggests they may have seen “a delay of clinical symptom decline in exploratory endpoints.”

Researchers used both the Clinical Dementia Rating Sum of Boxes as well as a new assessment they’ve been working on.

This wouldn’t be the first time researchers touted/hyped a possible tie to an improved cognitive score. Eli Lilly did it with great success on the second pivotal fail for solanezumab, setting up a third late-stage study that completely failed to show an improvement in cognition or function. Now they’re trying it in pre-symptomatic patients. And Biogen itself has regularly stoked hopes for aducanumab, its top late-stage drug in the Alzheimer’s field, where nothing has worked out in more than a decade.

Significantly, the researchers found no serious safety issues that could stop the program at this stage.

The latest setback for Merck also underscored fears that the entire BACE field is headed for the growing scrap heap of drugs — as far as symptomatic patients are concerned. Merck researchers concluded that their first Phase III trial also proved that their drug hit its target, without significantly helping patients. There have been a number of other BACE failures, but those setbacks have been blamed on the drug’s weaknesses, rather than problems with the target.

“It is highly encouraging that Study 202 confirmed elenbecestat’s treatment effect in reducing amyloid in the brain and suggested a slowing of clinical decline. Eisai and Biogen will continue to work together to advance the ongoing Phase III program (MISSION AD) in order to contribute a new potential treatment option to Alzheimer’s disease patients as soon as possible,” said Lynn Kramer, the CMO for Eisai’s Neurology Business Group. 

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