Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Total revenues	$ 1,241	$ 2,356
Operating expenses:
Research and development	8,949	13,515
General and administrative	3,205	7,686
Total operating expenses	12,154	21,201
Loss from operations	(10,913)	(18,845)
Other income:
Interest income and other, net	493	1,152
Net loss	(10,420)	(17,693)
Other comprehensive loss:
Unrealized (loss) gain on debt investments, net	(46)	140
Comprehensive loss	$ (10,466)	$ (17,553)
Per share information:
Net loss, basic and diluted (in dollars per share)	$ (0.17)	$ (0.35)
Weighted-average shares outstanding, basic and diluted (in shares)	61,742,035	50,887,221
Contract revenue
Total revenues	$ 1,171	$ 2,356
Licensing revenue
Total revenues	$ 70	$ 0