Inventory

Inventory consists of the following (in thousands):


	December 31,
	2023		2022
Raw materials	$	1,861	$	2,575
Work-in-process		12,880		10,749
Finished goods		1,360		5,878
Total inventory	$	16,101	$	19,202

For the year ended December 31, 2023, we recorded a provision of $2.0 million for the net realizable value of our batches as an increase to cost of goods sold. Our manufacturing agreement with UCB Pharma (UCB) provides for a fixed price which we had negotiated in exchange for a higher royalty rate. Accordingly, when evaluating the net realizable value of our inventory for UCB, we include the negotiated increase of the royalties in our analysis, and the aggregate revenue has historically been greater than our manufacturing cost. Due to the decrease in the royalty rate for 2024 as a result of a settlement agreement with UCB, the aggregate revenue is expected to be less than our manufacturing cost, and therefore we recorded a provision for net realizable value. See Note 5 for additional information on the settlement agreement with UCB.

During the three months ended September 30, 2023, we recorded a provision for inventory obsolescence of $3.7 million as an increase to cost of goods sold for certain batches produced in our Huntsville, Alabama manufacturing facility, as a result of our identification of a quality concern of a solvent obtained from a third party that was used in the manufacturing of these batches. In the three months ended December 31, 2023, based on further analysis and partner approval, we reversed the provision and recorded a $3.7 million benefit to cost of goods sold.

Other Current Assets

Other current assets consists of the following (in thousands):


	December 31,
	2023		2022
Prepaid research and development expenses	$	4,325	$	7,398
Non-trade receivables and other		1,047		2,423
Other prepaid expenses		4,407		5,987
Total other current assets	$	9,779	$	15,808

Property, Plant and Equipment

Property, plant and equipment consists of the following (in thousands):


	December 31,
	2023			2022
Building and leasehold improvements	$	43,184		$	74,889
Laboratory equipment		14,537			24,243
Computer equipment and software		22,438			26,205
Manufacturing equipment		24,315			25,052
Furniture, fixtures, and other		541			4,263
Depreciable property, plant and equipment at cost		105,015			154,652
Less: accumulated depreciation		(86,898	)		(124,731	)
Depreciable property, plant and equipment, net		18,117			29,921
Construction-in-progress		739			2,530
Property, plant and equipment, net	$	18,856		$	32,451

Laboratory and manufacturing equipment, including construction-in-process, include assets that support both our manufacturing and research and development activities.

As a result of the sustained decrease in the fair value of our single reporting unit during the three months ended March 31, 2023, plans to sublease all of our laboratory and office space, and the weakening sublease markets, we recorded non-cash impairment charges of $4.8 million for property, plant and equipment for the year-ended December 31, 2023, which we report in restructuring, impairment and costs of terminated program in our Consolidated Statement of Operations. See Note 8 for additional information.

Depreciation and amortization expense for property, plant and equipment for the years ended December 31, 2023, 2022, and 2021 was $7.0 million, $12.2 million, and $13.0 million, respectively.

Goodwill

The following is a reconciliation of the change in our goodwill for the year ended December 31, 2023 (in thousands):


	Year Ended December 31, 2023
Goodwill – beginning balance	$	76,501
Impairment of goodwill		(76,501	)
Goodwill – ending balance	$	—

As a result of the decrease in the fair value of our single reporting unit during the three months ended March 31, 2023, we recorded a non-cash goodwill impairment charge of $76.5 million, which we report as impairment of goodwill in our Consolidated Statement of Operations. We had previously recognized goodwill primarily from our acquisitions of Shearwater Corp. and Aerogen, Inc. in 2001 and 2005, respectively. See Note 9 for additional information.

Accrued Expenses

Accrued expenses consist of the following (in thousands):


	December 31,
	2023		2022
Accrued compensation	$	5,553	$	9,582
Accrued clinical trial expenses		4,321		12,262
Liability to collaboration partners		2,678		3,808
Accrued contract termination costs		3,020		3,902
Other accrued expenses		6,590		7,003
Total accrued expenses	$	22,162	$	36,557

Accumulated Other Comprehensive Income (Loss)

The following table summarizes the changes in accumulated other comprehensive income (loss) by component (in thousands):


	Foreign currency translation			Available-for-sale securities			Accumulated Other Comprehensive Income
Balance at December 31, 2022	$	(5,131	)	$	(1,776	)	$	(6,907	)
Foreign currency translation gain		62			—			62
Unrealized gain on available-for-sale securities		—			1,826			1,826
Reclassification adjustments to income		5,099			—			5,099
Balance at December 31, 2023	$	30		$	50		$	80

The reclassification from accumulated other comprehensive loss relates to the closure of the operations of our foreign subsidiaries and has been included within other income (expense), net in our Consolidated Statement of Operations for the year ended December 31, 2023.