CAPITALIZED FEES PAID TO A RELATED PARTY

12 Months Ended

Dec. 31, 2021

CAPITALIZED FEES PAID TO A RELATED PARTY

CAPITALIZED FEES PAID TO A RELATED PARTY

6. CAPITALIZED FEES PAID TO A RELATED PARTY

Capitalized fees paid to a related party, which consist of registrational and launch-related milestone fees paid to GSK, were as follows:

		December 31,
(In thousands)	Amortization period	2021			2020
United States	2013-2030	$	120,000		$	120,000
Europe	2013-2029		60,000			60,000
Japan	2013-2019		40,000			40,000
Gross carrying value			220,000			220,000
Accumulated amortization			(108,570	)		(94,747	)
Net carrying value		$	111,430		$	125,253

These milestone fees are amortized over their estimated useful lives commencing upon the commercial launch of the product in their respective regions with the amortization expense recorded as a reduction in revenue from collaborative arrangements. As of December 31, 2021, the weighted average remaining amortization period was 8.1 years.

Additional information regarding these milestone fees is included in Note 3, “Revenue Recognition and Collaborative Arrangements.” Amortization expense for each of the years ended December 31, 2021, 2020 and 2019 was $13.8 million. The remaining estimated amortization expense is $13.8 million for each of the years from 2022 to 2026 and $42.3 million thereafter.