Property and Equipment, Net

12 Months Ended

Dec. 31, 2017

Property Plant And Equipment [Abstract]

9. Property and Equipment, Net

Property and equipment, net as of December 31, 2017 and 2016 consisted of the following:

	December 31,
(in thousands)	2017			2016
Lab equipment	$	13,486		$	17,537
IT equipment		3,853			8,509
Leasehold improvements		20,790			20,633
Furniture and fixtures		335			626
Construction in process		30			378
Total property and equipment, gross		38,494			47,683
Less: Accumulated depreciation		(32,027	)		(33,471	)
Total property and equipment, net	$	6,467		$	14,212

Depreciation expense was $5.1 million, $6.5 million and $4.8 million for the years ended December 31, 2017, 2016 and 2015, respectively. Capitalized interest costs were insignificant for the years ended December 31, 2017, 2016 and 2015.

During the year ended December 31, 2016, the Company recognized a $0.5 million charge related to the disposal of property and equipment. There were no significant losses recognized related to the disposal of property and equipment during the years ended December 31, 2017 and 2015. During the years ended December 31, 2017 and 2016, the Company recognized a $0.4 million and less than $0.1 million gain on the sale of equipment, respectively. There were no significant gains recognized related to the sale of property and equipment during the year ended December 31, 2015.