Unaudited Quarterly Results (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Schedule of Results of Operations on Quarterly Basis

The results of operations on a quarterly basis for the years ended December 31, 2018 and 2017 are set forth below:

	March 31, 2018			June 30, 2018			September 30, 2018			December 31, 2018
	(Amounts in thousands except per share data)
Collaboration revenue	$	7,469		$	7,677		$	7,408		$	7,880
Operating expenses:
Research and development		22,493			23,467			23,237			19,918
General and administrative		7,406			7,805			8,270			8,708
Total operating expenses		29,899			31,272			31,507			28,626
Operating loss		(22,430	)		(23,595	)		(24,099	)		(20,746	)
Interest income		1,074			1,376			1,397			1,680
Net loss	$	(21,356	)	$	(22,219	)	$	(22,702	)	$	(19,066	)
Net loss per share, basic and diluted	$	(0.51	)	$	(0.52	)	$	(0.53	)	$	(0.43	)
Weighted average shares outstanding, basic    and diluted		42,043			42,836			43,161			44,215

	March 31, 2017			June 30, 2017			September 30, 2017			December 31, 2017
	(Amounts in thousands except per share data)
Collaboration revenue	$	6,215		$	5,917		$	7,317		$	6,668
Operating expenses:
Research and development		13,431			15,565			17,481			21,170
General and administrative		5,732			6,369			5,711			10,213
Total operating expenses		19,163			21,934			23,192			31,383
Operating loss		(12,948	)		(16,017	)		(15,875	)		(24,715	)
Interest income		317			424			519			752
Net loss	$	(12,631	)	$	(15,593	)	$	(15,356	)	$	(23,963	)
Net loss per share, basic and diluted	$	(0.36	)	$	(0.45	)	$	(0.44	)	$	(0.61	)
Weighted average shares outstanding, basic    and diluted		34,723			34,916			35,189			39,155