CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenue
Research and development revenue	$ 1,227	$ 2,785
Costs and expenses:
Research and development	4,198	4,413
General and administrative	2,044	3,187
Total costs and expenses	6,242	7,600
Loss from operations	(5,015)	(4,815)
Interest income	34	36
Other income		228
Net loss	(4,981)	(4,551)
Unrealized gain on marketable securities	29	11
Comprehensive loss	$ (4,952)	$ (4,540)
Basic and diluted net loss per share:
Net loss per share	$ (0.08)	$ (0.07)
Weighted average basic and diluted common shares outstanding	65,489	62,745