Inventory

6 Months Ended

Jun. 30, 2022

Inventory consists of the following (in thousands):


	June 30, 2022		December 31, 2021
Raw materials	$	2,099	$	3,166
Work-in-process	13,837		9,342
Finished goods	1,033		3,293
Total inventory	$	16,969	$	15,801

We manufacture finished goods inventory upon receipt of firm purchase orders, and we may manufacture certain intermediate work-in-process materials and purchase raw materials based on purchase forecasts from our collaboration partners. We include direct materials, direct labor, and manufacturing overhead in inventory and determine cost on a first-in, first-out basis for raw materials and on a specific identification basis for work-in-process and finished goods. We value inventory at the lower of cost or net realizable value, and we write down defective or excess inventory to net realizable value based on historical experience or projected usage. We expense inventory related to our research and development activities as manufactured by us or when purchased.