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Collaborative and Other Relationships - Summary of Activity Related to BAN2401 and Elenbecestat Collaboration (Details) - Eisai - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Collaborative arrangements and non-collaborative arrangement transactions |  |  |
Total development expense incurred by the collaboration related to the advancement of LEQEMBI | $ 347.2 | $ 323.0 | $ 219.3
Expense reflected within statements of income | 173.6 | 161.5 | 109.6
Selling, general and administrative | E2609 and BAN2401 |  |  |
Collaborative arrangements and non-collaborative arrangement transactions |  |  |
Expense reflected within statements of income | 52.3 | 13.6 | 4.9
Expense incurred by the collaboration | $ 104.6 | $ 27.2 | $ 9.8

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