Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 85,038	$ 56,537
Short-term investments	20,803	3,525
Prepaid clinical development costs	366	196
Other prepaid and current assets	560	362
Total current assets	106,767	60,620
Property and equipment, net	780	81
Intangible assets	56	56
Long-term investments	35,741	17,537
Total assets	143,344	78,294
Current liabilities:
Accounts payable	2,040	2,232
Current portion of long-term debt	638
Accrued clinical development costs	1,978	884
Other accrued liabilities	835	1,087
Total current liabilities	5,491	4,203
Long-term debt, net of discount	4,299
Total liabilities	9,790	4,203
Commitments and contingencies (Note 5)
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized and no shares issued or outstanding as of December 31, 2014 and December 31, 2013
Common stock, $0.001 par value; 120,000,000 shares authorized as of December 31, 2014 and December 31,2013; 20,352,876 shares issued 20,343,325 outstanding at December 31, 2014 and 15,357,413 shares issued and 15,340,710 outstanding at December 31, 2013	20	15
Additional paid-in capital	238,031	142,142
Accumulated other comprehensive loss	(59)	(3)
Accumulated deficit	(104,438)	(68,063)
Total stockholders' equity	133,554	74,091
Total liabilities and stockholders' equity	$ 143,344	$ 78,294