• On Thursday, Biogen presented additional aducanumab data at CTAD that answered some questions, and raised others

• Bulls believe the totality of the data, including the first positive pivotal trial in Alzheimer’s, is supportive of approval

• Bears believe the data is too confounding to receive approval

• Potential considerations beyond the stats could also potentially shift the odds of approval in Biogen’s favor

• Drug approval could add over $10B in gross revenue, but investors should consider the potential for a more narrow label

- Since releasing initial BAN2401 results in July, excitement among investors has waned as detailed analysis has shown confounding results. However, many investors still see promise in the drug.

- When viewed within the context of Biogen’s entire Alzheimer’s portfolio, Biogen remains well positioned to get an Alzheimer’s drug to market with aducanumab, BAN2401, and elenbecestat

- Amyloid beta hypothesis still has legs as drugs that target subtypes beyond monomers have shown some degree of clinical efficacy

- Possible futility analyses for aducanumab/crenezumab and FDA statement on ADCOMS as a legitimate endpoint are catalysts to watch, while aducanumab P3 readout in 2020 remains the key conclusive event.

- Biogen recently announced positive results from BAN2401's phase 2 trial that showed the potential to be the first disease-modifying drug on the market.

- Our current understanding of the underlying mechanisms of Alzheimer's Disease (AD) suggests that the removal of amyloid beta accumulation could slow the progress of AD. BAN2401 fits within this category.

- Investors and AD experts are debating the interpretation of the results. Study design and magnitude of the effect is in question, but overall results provide further validation of amyloid hypothesis. If successfully approved, the drug could generate $5+ billion in revenue.

- To better assess the odds of success, investors should look for more detailed BAN2401 results at the AAIC and monitor other drug developments for further validation, including aducanumab and crenezumab. Biogen also has another AD drug, elenbecestat that will be presented at the AAIC conference.