CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue:
Research and development revenue		$ 1,227
Costs and expenses:
Research and development	$ 5,194	4,198
General and administrative	2,074	2,044
Total costs and expenses	7,268	6,242
Loss from operations	(7,268)	(5,015)
Interest income	22	34
Interest expense	(330)
Net loss	(7,576)	(4,981)
Unrealized gain (loss) on marketable securities	(4)	29
Comprehensive loss	$ (7,580)	$ (4,952)
Basic and diluted net loss per share:
Net loss per share (in dollars per share)	$ (0.11)	$ (0.08)
Weighted average basic and diluted common shares outstanding (in shares)	71,138	65,489