7. Goodwill and Intangible Assets

Goodwill and intangible assets acquired are recognized at fair value as of the acquisition date. We recognized goodwill of $11.5 million and $6.4 million from our acquisitions of Entasis and La Jolla, respectively, in 2022. The carrying amount of goodwill as of March 31, 2025 and December 31, 2024 was $17.9 million. We have not recognized any impairment losses related to goodwill during the periods presented.

Intangible assets with definite lives are amortized over their estimated useful lives. The carrying basis and accumulated amortization of recognized intangible assets as of March 31, 2025 and December 31, 2024 were as follows:

Intangible assets recognized as a result of the acquisition of Entasis amounted to $106.7 million, which consisted of Entasis’ in-process research and development related to its antibacterial therapeutic product candidates and a collaboration agreement amounting to $71.3 million and $35.4 million, respectively. Following the FDA approval of XACDURO® in May 2023, we started amortizing $68.7 million of the then in-process research and development as a marketed product, as well as the collaboration agreement, over their estimated useful lives. The useful life of the remaining in-process research and development of $2.6 million, which pertains to zoliflodacin, will be determined upon commercialization of the underlying product candidate; thus, no amortization expense for this intangible asset was recognized for the periods presented.

Intangible assets recognized as a result of the acquisition of La Jolla amounting to $151.0 million pertain to product rights and developed technologies on La Jolla’s currently marketed products. These are intangible assets with determinable lives and are amortized over their estimated useful lives.

The upfront fee of $4.0 million paid to Basilea for the exclusive commercialization right of ZEVTERA® in the U.S. in December 2024 was recorded as an intangible asset and is being amortized over the initial term of the agreement (refer to Note 4, “License and Collaboration Arrangements”).

We recognized amortization expense of $6.5 million and $6.4 million for the three months ended March 31, 2025 and 2024, respectively. Future amortization expense is expected to be $19.8 million for the remainder of 2025, $26.3 million for each of the years from 2026 to 2029 and $74.3 million thereafter.