Intangible Assets

12 Months Ended

Dec. 31, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

Intangible Assets

Intangible assets. net consist of the following:

		As of December 31,
		2023						2022
(In millions)	Estimated Useful Life	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross carrying Amount		Accumulated Amortization		Net Carrying Amount
Acquired product rights - Libtayo	13 years	$	1,119.1	$	(126.7)	$	992.4	$	946.3	$	(35.7)	$	910.6
Other intangibles	8 years	10.0		(6.3)		3.7		10.0		(5.1)		4.9
Acquired in-process research and development	Indefinite	42.5		—		42.5		—		—		—
		$	1,171.6	$	(133.0)	$	1,038.6	$	956.3	$	(40.8)	$	915.5

As described in Note 3, during the year ended December 31, 2023, the Company recorded an indefinite-lived intangible asset of $42.5 million in connection with its acquisition of Decibel.

During the year ended December 31, 2022, the Company recorded an intangible asset in connection with obtaining the exclusive right to develop, commercialize, and manufacture Libtayo worldwide. The intangible asset recognized upon the effective date of the A&R IO LCA primarily consisted of the $900.0 million up-front payment, offset by the remaining IO Collaboration other liabilities balance of $241.0 million. Additionally, during the years ended December 31, 2023 and 2022, the Company recorded additions to the Libtayo intangible asset related to contingent consideration (including regulatory and sales-based milestones) due to Sanofi. See Note 3.

Amortization expense on intangible assets was $92.2 million and $37.6 million for the years ended December 31, 2023 and 2022, respectively. Amortization expense for the year ended December 31, 2021 was not material.

As of December 31, 2023, assuming no changes in the gross carrying amount of intangible assets, amortization expense is estimated to be approximately $85 million for each of the years ending December 31, 2024 through December 31, 2028.