# Biogen Stocks Fall As They Tweak Their Research

Published 2018-02-23 · Updated 2026-07-23 · Healthcare on MarketScale
Canonical: https://www.marketscale.com/industries/healthcare/biogen-stocks-fall-tweak-research

> The Biotechnology company Biogen is changing plans for their study on Alzheimer’s based on mid-study findings, making investors less confident. Based on their findings, 510 patients will need to be added to the final stage of the study. Biogen CMO Al Sandrock said, “ We did do a preplanned blinded sample size re-estimation. We…

The Biotechnology company Biogen is changing plans for their study on Alzheimer’s based on mid-study findings, making investors less confident. Based on their findings, 510 patients will need to be added to the final stage of the study. Biogen CMO Al Sandrock said, “ *We did do a preplanned blinded sample size re-estimation. We did see more variability in the primary endpoint than assumed when we did the original sample size estimation, so we decided to increase the sample size to maintain 90% power. Therefore, we’re going to add 510 patients to the two studies*.” With the recent changes and growing concerns for their stockholders, hopefully Biogens study will still pay off.

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