Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue
Operating expenses:
Research and development	41,759	20,593
General and administrative	12,508	12,773
Severance expense	1,636
Total operating expenses	55,903	33,366
Loss from operations	(55,903)	(33,366)
Other (expense) income:
Gain on extinguishment of debt	2
Interest expense related to amortization of debt issuance costs and discount	(1,618)	(1,561)
Interest expense on principal	(5,469)	(5,776)
Fair value adjustment related to derivative and warrant liability	5,976	(3,091)
Interest and other income, net	420	365
Total other (expense) income	(689)	(10,063)
Loss before income taxes	(56,592)	(43,429)
Income tax benefit	126	43
Net loss	$ (56,466)	$ (43,386)
Net loss per share:
Basic and diluted (in dollars per share)	$ (3.15)	$ (2.96)
Weighted average number of shares of common stock outstanding:
Basic and diluted (in shares)	17,930,023	14,652,898