BIIB - Clinical PoC Achieved with Convincing Tau-PET Reductions Across All Doses; Unexplained Inverse Dose-response Clouds Phase 3; BIIB's Investor Presentation at Noon

Research evidence excerpt

BIIB - Clinical PoC Achieved with Convincing Tau-PET Reductions Across All Doses; Unexplained Inverse Dose-response Clouds Phase 3; BIIB's Investor Presentation at Noon

FLASH NOTE

July 14, 2026

Yatin Suneja yatin.suneja@guggenheimpartners.com BIIB - Clinical PoC Achieved with Convincing Tau-

212 518 9565 PET Reductions Across All Doses; Unexplained

Delma Caiati, M.D., Ph.D.

delma.caiati@guggenheimpartners.com Inverse Dose-response Clouds Phase 3; BIIB's

617 859 4606 Investor Presentation at Noon Eddie Hickman, Ph.D.

eddie.hickman@guggenheimpartners.com

212 518 9904 Key Message: In the 416-patient Ph 2 CELIA study, BIIB080 produced robust, dose-

Min Lee, Ph.D. dependent reductions in CSF total tau and marked declines in tau PET across all dose

min.lee@guggenheimpartners.com regimens. Clinically, all active arms showed numerical benefit over placebo on CDR-

212 823 6744 SB and on most cognitive/composite endpoints at week 76, but the prespecified dose-

response primary endpoint was not met (as previously announced by the company). The Iris Gao, Ph.D.

iris.gao@guggenheimpartners.com lowest dose arm (n=60; 60mg Q6M) showed the largest effects, including 26% slowing

212 518 9013 on CDR-SB, 42% on ADAS-Cog13, 50% on MMSE and 30% on modified iADRS, while

ADCS-ADL-MCI was inconsistent, and safety worsened with exposure, including more

confusional events, treatment-related AEs/SAEs and higher discontinuation at higher

doses. We believe the overall data provide a good proof-of-concept, although the

inverse dose pattern remains unresolved. A plateau may be reached once tau is BIIB

Biogen Inc. reduced by ~50%, with the low-dose advantage amplified by sampling variation

Sector: Biotechnology and potentially by baseline differences. A high-dose tolerability penalty may also