CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIENCY) - USD ($) $ in Thousands	Common Stock Subscription Agreement	Common Stock Private Placement	Common Stock Public Offering	Common Stock	Additional Paid-in Capital Subscription Agreement	Additional Paid-in Capital Private Placement	Additional Paid-in Capital Public Offering	Additional Paid-in Capital	Other Comprehensive Loss	Accumulated Deficit	Subscription Agreement	Private Placement	Public Offering	Total
Balance at the beginning of the period at Dec. 31, 2016								$ 145	$ 294	$ (100,670)				$ (100,231)
Increase (Decrease) in Stockholders' Equity
Accretion of redeemable preferred stock to redemption value								(244)						(244)
Conversion of notes payable-related party and accrued interest into common stock				$ 2				31,143						31,145
Conversion of notes payable-related party and accrued interest into stock (in shares)				1,950,768
Conversion of convertible preferred stock to common stock				$ 3				70,772						70,775
Conversion of convertible preferred stock to common stock (in shares)				3,174,523
Issuance of common stock, net of issuance costs	$ 1	$ 3			$ 8,981	$ 5,426					$ 8,982	$ 5,429
Issuance of stock (in shares)	1,010,225	2,958,094
Issuance of common stock in connection with merger with Macrocoure, net of offering costs of $1,331				$ 3				19,927						19,930
Issuance of common stock in connection with merger with Macrocoure, net of offering costs of $1,331 (in shares)				3,256,898
Issuance of common stock upon exercise of stock options								20						$ 20
Issuance of common stock upon exercise of stock options (in shares)				3,506										3,506
Foreign currency translation adjustment									(562)					$ (562)
Stock-based compensation								5,600						5,600
Net loss										(29,727)				(29,727)
Balance at the end of the period at Dec. 31, 2017				$ 12				141,770	(268)	(130,397)				11,117
Balance at the end of the period (in shares) at Dec. 31, 2017				12,354,014
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net of issuance costs			$ 3				$ 14,793						$ 14,796
Issuance of stock (in shares)			2,146,667
Issuance of common stock upon exercise of warrants								2,347						2,347
Issuance of common stock upon exercise of warrants (in shares)				200,000
Issuance of common stock upon exercise of stock options								14						$ 14
Issuance of common stock upon exercise of stock options (in shares)				2,478										2,478
Foreign currency translation adjustment									570					$ 570
Stock-based compensation								3,469						3,469
Net loss										(23,138)				(23,138)
Balance at the end of the period at Dec. 31, 2018				$ 15				$ 162,393	$ 302	$ (153,535)				$ 9,175
Balance at the end of the period (in shares) at Dec. 31, 2018				14,703,159