Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 48,638	$ 56,537
Short-term investments	8,064	3,525
Prepaid clinical development costs	1,257	196
Other prepaid and current assets	320	362
Total current assets	58,279	60,620
Property and equipment, net	360	81
Intangible assets	56	56
Investments	11,528	17,537
Total assets	70,223	78,294
Current liabilities:
Accounts payable	2,098	2,232
Accrued clinical development costs	526	884
Other accrued liabilities	564	1,087
Total current liabilities	3,188	4,203
Total liabilities	3,188	4,203
Commitments and contingencies (Note 5)
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized as of March 31, 2014 and December 31, 2013; no shares issued or outstanding at March 31, 2014 and December 31, 2013
Common stock, $0.001 par value; 120,000,000 shares authorized as of March 31, 2014 and December 31, 2013; 15,394,226 shares issued and 15,379,311 outstanding at March 31, 2014 and 15,357,413 shares issued and 15,340,710 outstanding at December 31, 2013	15	15
Additional paid-in capital	142,954	142,142
Accumulated other comprehensive income	3	(3)
Deficit accumulated during the development stage	(75,937)	(68,063)
Total stockholders' equity	67,035	74,091
Total liabilities and stockholders' equity	$ 70,223	$ 78,294