Property and Equipment

12 Months Ended

Dec. 31, 2015

Property Plant And Equipment [Abstract]

Property and Equipment

4. Property and Equipment

Property and equipment consists of the following:

	Estimated Useful Life	December 31, 2015			December 31, 2014
			(in thousands)
Laboratory equipment	5 years	$	—		$	7,671
Computer equipment and software	3 years		187			3,913
Office furniture	5 years		—			893
Leasehold improvements	Shorter of asset’s useful life or remaining term of lease		—			14,433
			187			26,910
Less accumulated depreciation and amortization			(164	)		(15,615	)
Property and equipment, net		$	23		$	11,295

Depreciation expense for the years ended December 31, 2015, 2014 and 2013 was $9.6 million, $6.2 million and $3.8 million, respectively. In September 2014, the Company entered into a Lease Termination Agreement, pursuant to which the Company agreed to surrender the remaining 49,185 square feet of leased space no later than September 24, 2015. As a result, the Company revised the estimated useful life of its leasehold improvements related to this space, resulting in an increase in depreciation expense of approximately $2.4 million during the year ended December 31, 2014. In February 2015, the Company provided notice that it would surrender the remaining space on May 29, 2015. Accordingly, the Company again revised the estimated useful life of its leasehold improvements related to this office space and amortized such assets through May 2015, resulting in an additional $2.9 million of depreciation expense during the year ended December 31, 2015.