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Collaborative and Other Relationships (Tables) | 9 Months Ended
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Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Summary of Activity Related to BAN2401 and Elenbecestat Collaboration | A summary of development expense related to the BAN2401 and Elenbecestat Collaboration is as follows:
| For the Three Months Ended September 30, |  | For the Nine Months Ended September 30,
(In millions) | 2019 |  | 2018 |  | 2019 |  | 2018
Total development expense incurred by the collaboration related to the advancement of BAN2401 and elenbecestat | $ | 168.7 |  |  | $ | 64.9 |  |  | $ | 305.3 |  |  | $ | 176.0 |
Biogen's share of BAN2401 and elenbecestat development expense reflected in research and development expense in our condensed consolidated statements of income | $ | 84.3 |  |  | $ | 32.5 |  |  | $ | 152.6 |  |  | $ | 88.0 |
Summary of Activity Related to Aducanumab Collaboration | A summary of development and sales and marketing expense related to the Aducanumab Collaboration Agreement is as follows:
| For the Three Months Ended September 30, |  | For the Nine Months Ended September 30,
(In millions) | 2019 |  | 2018 |  | 2019 |  | 2018
Total aducanumab development expense | $ | 4.7 |  |  | $ | 64.8 |  |  | $ | 170.5 |  |  | $ | 204.8 |
Biogen's share of aducanumab development expense reflected in research and development expense in our condensed consolidated statements of income | $ | 2.6 |  |  | $ | 55.1 |  |  | $ | 93.8 |  |  | $ | 183.6 |
Total aducanumab sales and marketing expense incurred by the collaboration | $ | 0.1 |  |  | $ | 12.1 |  |  | $ | 21.3 |  |  | $ | 33.3 |
Biogen's share of aducanumab sales and marketing expense reflected in selling, general and administrative expense in our condensed consolidated statements of income | $ | — |  |  | $ | 5.1 |  |  | $ | 11.7 |  |  | $ | 19.0 |

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