Quarterly Results (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Results

	Three Months Ended
	March 31, 2015			June 30, 2015			September 30, 2015			December 31, 2015
	(in thousands, except per share data)
	(unaudited)
Collaboration revenue	$	134		$	134		$	15,158		$	3,598
Restructuring		4,333			25			─			─
Operating expenses		5,950			4,730			6,691			9,721
Loss from operations		(10,149	)		(4,621	)		8,467			(6,123	)
Other expense, net		(725	)		(835	)		(553	)		(462	)
Net loss	$	(10,874	)	$	(5,456	)	$	7,914		$	(6,585	)
Net loss per share—basic and diluted	$	(0.21	)	$	(0.10	)	$	0.14		$	(0.11	)

	Three Months Ended
	March 31, 2014			June 30, 2014			September 30, 2014			December 31, 2014
	(in thousands, except per share data)
	(unaudited)
Collaboration revenue	$	15,289		$	1,846		$	873		$	115
Restructuring		3,859			5,165			1,403			1,302
Operating expenses		17,322			14,146			13,569			11,806
Loss from operations		(5,892	)		(17,465	)		(14,099	)		(12,993	)
Other expense, net		(558	)		(494	)		(337	)		(901	)
Net loss	$	(6,450	)	$	(17,959	)	$	(14,436	)	$	(13,894	)
Net loss per share—basic and diluted	$	(0.12	)	$	(0.35	)	$	(0.28	)	$	(0.27	)