Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 9,053	$ 54,220
Marketable securities	48,981	22,511
Prepaid expenses and other current assets	1,698	786
Restricted cash	205	205
Total current assets	59,937	77,722
Marketable securities, non-current	752
Property and equipment, net	334	276
Restricted cash	193
Other assets	121	706
Total assets	61,337	78,704
Current liabilities:
Accounts payable	2,658	3,197
Accrued compensation	1,009	1,091
Accrued research and clinical liabilities	2,208	3,309
Notes payable, short-term	5,131	3,182
Other accrued liabilities	492	603
Total current liabilities	11,498	11,382
Notes payable, long-term	8,292	6,786
Deferred rent, long-term	157
Total liabilities	19,947	18,168
Commitments and contingencies (Note 7)
Stockholders' equity (deficit):
Common stock, $0.001 par value: 85,000,000 shares and 47,500,000 shares authorized at June 30, 2014, and December 31, 2013 respectively; 32,981,396 and 32,931,092 shares issued and outstanding at June 30,2014, and December 31, 2013, respectively	33	33
Additional paid-in capital	201,793	200,715
Accumulated other comprehensive income	1	3
Accumulated deficit	(160,437)	(140,215)
Total stockholders' equity	41,390	60,536
Total liabilities and stockholders' equity	$ 61,337	$ 78,704