Biogen shares tumble after key exec notes a changeup to pivotal aducanumab study due to ‘variability’

With news of Merck’s flagship BACE drug going down to complete failure in a late-stage Alzheimer’s study still reverberating through a dispirited R&D field, Biogen is now pitching in to make things even worse.

Al Sandrock, Biogen

Shares of Biogen $BIIB tumbled about 7% Wednesday afternoon after their CMO Al Sandrock shocked some attendees at the Leerink Healthcare Conference by saying that the company had decided to add 510 patients to its pivotal study for the closely-watched drug aducanumab.

Sandrock told attendees that they needed to add hundreds of patients to the study due to some “variability” they were seeing in the data from the first round of patients to reach the primary endpoint.

Biogen couldn’t have picked a worse time for the disclosure.

The drumbeat of negative results for every late-stage effort aimed at amyloid beta has begun to shake a once-solid belief that the clusters of toxic protein found in many — though not all — patients had to be the culprit for a disease that afflicts millions of people the world over.

Geoffrey Porges, who follows the drug closely, noted:

The expansion in enrollment decision was made by the company after they analyzed blinded results for the performance of the primary endpoint (18 month CDR-SB) in the patients who have reached the primary endpoint so far. These additional patients are required to maintain 90% power for the trials due to “variability”. Biogen has not seen the data by arm, but to maintain the powering needed to add the additional enrollees given the variance seen so far. Biogen indicated that because of the accelerated early enrollment in the trial they could still maintain approximately the same timing for full enrollment, and suggested that they expect full enrollment “in the summer” and expect final results now in the early part of 2020. The company also commented that the drop out rate had been lower than expected, and that the rate of serious adverse events, and ARIA-E in particular, had been within their expectations. In the context of Merck’s (MP) recent disappointment with the Merck BACE inhibitor verubecestat, Biogen’s aducanumab is one of what is now only a handful of Alzheimer’s medicines still active in pivotal trials.

The positive data that Biogen had disclosed from smaller studies had gone a long way to raising hopes that Biogen could actually make a breakthrough here, even as serious safety issues arose. Anything that raises doubts about efficacy can’t help Biogen, even as it insists that the company remains confident in the amyloid beta theory.

Michael Yee at Jefferies noted this afternoon that the study data remains blinded and is even less likely to read out significant data points before it’s completed way out in 2020. He sees today’s event as a wake up call for Biogen to get busy and buy something the market won’t fret about.

Market will swing back to uncertainty on the Alzheimer’s pendulum based on trial changes, and given data is not likely until 2020 (in our view) and an interim seems unlikely given disclosures about variability, while we maintain a positive stance on data in 2020, we think co needs to go out and buy de-risked neuro/orphan companies to “change the narrative” to being a binary Alzheimer’s company to one with products even if Alzheimer’s doesn’t work.

Good luck with that.

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Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
Director of Operations
Atlas Venture Cambridge, MA

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