BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 19,531	$ 26,178
Short-term investments	744	3,922
Prepaid expenses and other current assets	684	199
Total current assets	20,959	30,299
Property and equipment, net	1,136	1,148
Total assets	22,095	31,447
Current liabilities:
Current portion of notes payable	3,497	3,500
Accounts payable	1,161	2,809
Accrued expenses	1,016	1,775
Total current liabilities	5,674	8,084
Notes payable		1,743
Other long-term liabilities	132	141
Total liabilities	5,806	9,968
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, 22,448,735 issued and 22,419,504 outstanding at June 30, 2017 and 19,734,351 issued and 19,705,120 outstanding at December 31, 2016	23	20
Additional paid-in capital	152,085	147,288
Treasury stock at cost, 29,231 shares at June 30, 2017 and December 31, 2016
Accumulated deficit	(135,819)	(125,829)
Total stockholders’ equity	16,289	21,479
Total liabilities and stockholders’ equity	$ 22,095	$ 31,447