Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 38,750	$ 31,948
Accounts receivable	715	520
Prepaid expenses and other	310	387
Total current assets	39,775	32,855
Equipment, net	1,343	1,333
Total assets	41,118	34,188
Current liabilities:
Accounts payable	2,817	2,243
Accrued compensation and related benefits	731	1,067
Accrued clinical trial costs	104	88
Accrued expenses	641	884
Deferred revenue	24	86
Note payable	179
Total current liabilities	4,496	4,368
Note payable		176
Warrant liabilities	5,744	9,823
Stockholders' equity:
Preferred stock, at stated value; 10,000,000 shares authorized, and no shares issued and outstanding at June 30, 2014 and December 31, 2013	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized, and 77,247,412 and 70,749,212 shares issued at June 30, 2014 and December 31, 2013, respectively, and 77,247,412 and 70,683,480 shares outstanding at June 30, 2014 and December 31, 2013, respectively	77	71
Additional paid-in capital	306,048	284,323
Treasury stock, at cost; 65,732 shares at December 31, 2013		(135)
Accumulated deficit	(275,247)	(264,438)
Total stockholders' equity	30,878	19,821
Total liabilities and stockholders' equity	$ 41,118	$ 34,188