Capitalized Fees Paid to a Related Party

6 Months Ended

Jun. 30, 2016

Capitalized Fees Paid to a Related Party

Capitalized Fees Paid to a Related Party

5. 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:

June 30, 2016

December 31, 2015

Weighted

Average

Remaining

Amortization

Gross

Net

Gross

Net

Period

Carrying

Accumulated

Carrying

Carrying

Accumulated

Carrying

(In thousands)

(Years)

Value

Amortization

Value

Value

Amortization

Value

Approval and launch related milestone payments under the LABA Collaboration

13.6

$

220,000

$

(32,544

)

$

187,456

$

220,000

$

(25,632

)

$

194,368

These milestone fees are being 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.

Additional information regarding these milestone fees is included in Note 3, “Collaborative Arrangements.” Amortization expense for the three and six months ended June 30, 2016 and 2015 was $3.5 million and $6.9 million, respectively. As of June 30, 2016, the remaining estimated amortization expense is $6.9 million for 2016, $13.8 million for each of the years from 2017 to 2021, and an aggregate of $111.4 million thereafter.