Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 100,916	$ 85,586
Short-term investments	57,873	54,339
Prepaid expenses and other current assets	1,118	1,122
Total current assets	159,907	141,047
Long-term investments	4,140	18,275
Furniture, fixtures and equipment, net	1,703	240
Other assets, net	10,587	1,523
Total assets	176,337	161,085
Current liabilities
Accounts payable and other current liabilities	17,710	8,336
Interest payable	545	551
Total current liabilities	18,255	8,887
Convertible notes, net of discounts	124,218	124,156
Total liabilities	$ 142,473	$ 133,043
Commitments and contingencies
Stockholders’ equity
Preferred stock, $0.001 par value; 15,000,000 shares authorized as of June 30, 2015 and December 31, 2014; None issued and outstanding	$ 0	$ 0
Common stock, $0.001 par value; 150,000,000 shares authorized as of June 30, 2015 and December 31, 2014; 25,499,192 and 24,018,577 shares issued and outstanding as of June 30, 2015 and December 31, 2014, respectively	25	24
Additional paid-in capital	213,106	171,326
Accumulated other comprehensive loss	(41)	(107)
Accumulated deficit	(179,226)	(143,201)
Total stockholders’ equity	33,864	28,042
Total liabilities and stockholders’ equity	$ 176,337	$ 161,085