Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 91,060	$ 85,586
Short-term investments	45,502	54,339
Prepaid expenses and other current assets	1,865	1,122
Total current assets	138,427	141,047
Long-term investments	13,808	18,275
Furniture, fixtures and equipment, net	3,816	240
Other assets, net	3,076	273
Total assets	159,127	159,835
Current liabilities
Accounts payable and other current liabilities	16,565	8,336
Interest payable	551	551
Total current liabilities	17,116	8,887
Convertible notes, net of discounts and debt issuance costs	123,236	122,906
Total liabilities	$ 140,352	$ 131,793
Commitments and contingencies
Stockholders’ equity
Preferred stock, $0.001 par value; 15,000,000 shares authorized as of December 31, 2015 and December 31, 2014; None issued and outstanding	$ 0	$ 0
Common stock, $0.001 par value; 150,000,000 shares authorized as of December 31, 2015 and December 31, 2014; 26,458,495 and 24,018,577 shares issued and outstanding as of December 31, 2015 and December 31, 2014, respectively	26	24
Additional paid-in capital	236,492	171,326
Accumulated other comprehensive loss	(179)	(107)
Accumulated deficit	(217,564)	(143,201)
Total stockholders’ equity	18,775	28,042
Total liabilities and stockholders’ equity	$ 159,127	$ 159,835