BIIB: BIIB080 Shows Signals, But Few Details Makes It Difficult To Square Company's Enthusiasm

Research evidence excerpt

BIIB: BIIB080 Shows Signals, But Few Details Makes It Difficult To Square Company's Enthusiasm

EQUITY RESEARCH QUICK TAKE

RBC Capital Markets, LLC

Brian Abrahams, M.D. (Head of Global

Healthcare Research)

Kevin Meli, Ph.D. (Senior Associate)

Nevin Varghese, Ph.D. (Analyst)

May 14, 2026

Biogen Inc.

BIIB080 Shows Signals, But Few Details Makes It Difficult To Square Company's

Enthusiasm

NASDAQ: BIIB | USD 204.53 | Outperform | Price Target USD 222.00

Sentiment: Neutral

This morning, BIIB disclosed topline data from the ph.II CELIA study of intrathecal Tau antisense BIIB080 in Alzheimer's disease,

and we had a chance to connect with the company. The company expressed considerable enthusiasm about the data and plans

to move the drug into registrational studies.

The primary endpoint of dose-response on CDR-SB (recall, the doses were 115mg Q24W, 115mg Q12W, 60mg Q24W) was not

reached, though pre-specified analyses reportedly showed cognitive decline across all doses studied, particularly at the lowest

60mg Q24W dose. We did not get the sense there were major differences in Tau reductions across the arms, so this better efficacy

is curious (suggesting ph.Ib data could have been potentially driven by certain outliers rather than a true underlying dose-response

relationship). The company is not providing any sense as to the magnitude of the efficacy on slowing cognitive decline that they

observed - something that will be key to assess the potential of the drug - details are expected at AAIC in July.

On the other hand, "robust" reductions in CSF and PET Tau were observed across all doses, potentially supportive of the initial PD

data signals seen in ph.Ib, in which pt numbers had been too small to be entirely confident.