Biogen ($BIIB) Investor Settlement

Biogen has reached a settlement to resolve investor claims that it misled the market about aducanumab's clinical trial data and the "dosage" explanation for its failed ENGAGE study.

Outline:

On October 22, 2019, Biogen told investors that patients who received sufficient exposure to high-dose aducanumab in its failed ENGAGE trial showed results supporting the positive findings of its EMERGE trial. Through December 2019 and into 2020, Biogen kept presenting this "dosage" explanation as the reason ENGAGE failed while EMERGE succeeded. On November 4-6, 2020, the FDA's Advisory Committee reviewed data Biogen had not disclosed and voted 10-0 that the trial results did not support approval. The case has now moved to a tentative settlement.

Timeline:

• October 22, 2019: Biogen held a call announcing aducanumab's "revival," telling investors sufficient exposure to high-dose aducanumab reduced clinical decline and that ENGAGE data supported EMERGE's results.

• December 5, 2019: At the CTAD conference, Biogen presented a post-hoc analysis claiming a subset of ENGAGE patients supported EMERGE's positive findings, without disclosing internal data undermining that claim.

• November 4, 2020: The FDA released briefing materials for its Advisory Committee meeting, including a critical statistical report from FDA reviewer Dr. Tristan Massie that was buried in the documents.

• November 5, 2020: Biogen's stock fell 7.5% as investors began digesting the statistical concerns.

• November 6, 2020: The FDA's Advisory Committee voted 10-0 that the trial data did not support finding aducanumab effective; trading in Biogen's stock was halted.

• November 9, 2020: Biogen's stock fell 28.2% when trading resumed, closing at $236.26.

• November 13, 2020: Initial complaint filed.

• August 6, 2026: The parties informed the court they had settled in principle, pending finalization of terms.

Background:

Aducanumab was developed by Biogen as a treatment to slow cognitive decline in Alzheimer's patients by targeting amyloid plaque in the brain. In March 2019, Biogen halted its Phase III clinical trials after a futility analysis suggested the drug was unlikely to succeed, and the stock fell nearly 29% in a single day.

Months later, Biogen told investors that a new analysis of a larger dataset showed the drug worked after all — one trial (EMERGE) showed a positive result, while the other (ENGAGE) did not. Biogen explained the discrepancy by claiming ENGAGE patients hadn't received enough of the high (10mg/kg) dose in time, and that patients who did receive sufficient exposure showed results consistent with EMERGE's success.

Investors say that picture was misleading. According to the complaint, Biogen's own statisticians had repeatedly tested and rejected this dosage explanation internally — patients who always received the full dose in one subgroup saw almost no benefit, and some lower-dosed patients performed as well or better than higher-dosed ones. The FDA's own lead statistician, Dr. Tristan Massie, raised these same objections to Biogen throughout 2019 and 2020 and was later excluded from the working groups analyzing the data.

The market learned more when the FDA released its Advisory Committee briefing materials on November 4, 2020, which included Dr. Massie's critical, if buried, statistical review. As analysts and outside experts absorbed the report over the following days, Biogen's stock fell sharply, and the Advisory Committee ultimately voted 10-0 against finding the data supportive of approval. The matter has now moved to a tentative settlement.

What Can Investors Expect Now?

Biogen has reached a settlement to resolve investor claims that it misled the market about aducanumab's clinical trial data and the "dosage" explanation for its failed ENGAGE study.

If you were damaged due to this situation, you can file for a payout and get your share of the settlement. You can check if you are eligible and other details in the FAQ section.