Collaborative and Other Relationships (Tables)

9 Months Ended

Sep. 30, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Activity Related to BAN2401 and Elenbecestat Collaboration

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2022		2021		2022		2021
Total development expense incurred by the collaboration related to the advancement of lecanemab and elenbecestat	$	109.3	$	118.4	$	264.9	$	236.1
Biogen's share of lecanemab and elenbecestat development expense reflected in research and development expense in our condensed consolidated statements of income	54.7		59.2		132.5		118.0
Total sales and marketing expense incurred by the Lecanemab Collaboration	29.0		5.6		68.3		15.6
Biogen's share of lecanemab and elenbecestat sales and marketing expense reflected in selling, general and administrative expense in our condensed consolidated statements of income	14.5		2.8		34.2		7.8

Summary of Activity Related to Aducanumab Collaboration

A summary of development expense, sales and marketing expense and milestone payments related to the ADUHELM Collaboration Agreement is as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2022		2021		2022		2021
Total ADUHELM development expense	$	34.6	$	43.7	$	116.0	$	132.8
Biogen's share of ADUHELM development expense reflected in research and development expense in our condensed consolidated statements of income	19.0		24.0		63.8		73.0
Total ADUHELM sales and marketing expense incurred by the ADUHELM Collaboration Agreement	(8.0)		154.3		127.8		391.7
Biogen's share of ADUHELM sales and marketing expense reflected in selling, general and administrative expense and collaboration profit (loss) sharing in our condensed consolidated statements of income	(3.9)		83.3		68.1		211.2
Total ADUHELM collaboration third party milestones	—		—		—		100.0
Biogen's share of reimbursement from Eisai of ADUHELM milestone payments reflected in collaboration profit (loss) sharing in our condensed consolidated statements of income	—		—		—		45.0

Summary of Activity Related to Denali Therapeutics Collaboration

A summary of development expense related to this collaboration is as follows:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2022		2021		2022		2021
Total Denali collaboration development expense	$	19.9	$	8.5	$	58.0	$	27.2
Biogen's share of Denali development expense reflected in research and development expense in our condensed consolidated statements of income	11.4		5.1		33.5		16.3