Collaborative and Other Relationships (Tables)

9 Months Ended

Sep. 30, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

As a result of the FDA approval of LUNSUMIO our share of the combined annual co-promotion profits for RITUXAN and LUNSUMIO in excess of $50.0 million varies upon the following events, as summarized in the table below:




After LUNSUMIO Approval until the First Threshold Date	37.5	%
After First Threshold Date until the Second Threshold Date	35.0	%
After Second Threshold Date	30.0	%

Summary of Activity Related to BAN2401 and Elenbecestat Collaboration

A summary of development and sales and marketing expense related to the LEQEMBI Collaboration is as follows:


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Total development expense incurred by the collaboration related to the advancement of LEQEMBI	$	70.9	$	77.7	$	178.4	$	255.6
Biogen's share of the LEQEMBI Collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	35.4		38.8		89.2		127.8
Total sales and marketing expense incurred by the LEQEMBI Collaboration	176.8		164.6		525.7		476.2
Biogen's share of the LEQEMBI Collaboration sales and marketing expense reflected in selling, general and administrative expense in our condensed consolidated statements of income	88.3		82.3		262.8		238.1

Summary of activity related to the UCB collaboration

A summary of development expense related to the UCB collaboration agreement is as follows:


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Total UCB collaboration development expense	$	23.2	$	19.2	$	62.8	$	52.3
Biogen's share of the UCB collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	11.6		9.5		31.4		26.1

Summary of Activity Related to Sage Therapeutics

A summary of development and sales and marketing expense related to the Supernus collaboration is as follows:


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Total Supernus collaboration development expense	$	(1.7)	$	8.4	$	2.2	$	29.6
Biogen's share of the Supernus collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	(0.9)		4.2		1.1		14.8
Total sales and marketing expense incurred by the Supernus collaboration	41.8		28.4		131.0		82.9
Biogen's share of the Supernus collaboration sales and marketing expense reflected in selling, general and administrative expense and collaboration profit sharing/(loss reimbursement) in our condensed consolidated statements of income	20.9		14.2		65.5		41.5

Summary of Activity Related to Denali Therapeutics Collaboration

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


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
(In millions)	2025		2024		2025		2024
Total Denali collaboration development expense	$	11.4	$	14.9	$	36.3	$	44.5
Biogen's share of the Denali collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	6.9		8.9		21.8		26.7

Summary of Activity Related to Stoke Therapeutics Collaboration

A summary of development expense related to the Stoke collaboration agreement is as follows:



(In millions)	For the Three Months Ended September 30, 2025		For the Nine Months Ended September 30, 2025
Total Stoke collaboration development expense	$	9.1	$	21.9
Biogen's share of the Stoke collaboration development expense reflected in research and development expense in our condensed consolidated statements of income	2.8		6.6