CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 19,662	$ 33,531
Short-term investments	19,967	19,861
Prepaid expenses and other current assets	1,188	978
Total current assets	40,817	54,370
Property and equipment, net	1,282	1,338
Investments		4,964
Total assets	42,099	60,672
Current liabilities:
Accounts payable	2,917	927
Accrued expenses	3,960	1,617
Total current liabilities	6,877	2,544
Other long-term liabilities	100	120
Total liabilities	6,977	2,664
Stockholders' equity:
Preferred stock, $0.001 par value; 25,000,000 shares authorized, no shares issued and outstanding
Common stock, $0.001 par value; 100,000,000 shares authorized, 40,554,244 issued and 40,525,013 outstanding at September 30, 2018 and 40,549,936 issued and 40,520,705 outstanding at December 31, 2017	41	41
Additional paid-in capital	206,450	202,790
Treasury stock at cost, 29,231 shares at September 30, 2018 and December 31, 2017
Accumulated other comprehensive loss	(28)	(96)
Accumulated deficit	(171,341)	(144,727)
Total stockholders’ equity	35,122	58,008
Total liabilities and stockholders’ equity	$ 42,099	$ 60,672