Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 44,370	$ 28,518
Marketable securities	179,643	76,758
Prepaid expenses and other current assets	3,063	2,057
Total current assets	227,076	107,333
Property and equipment, net	951	842
Other assets	251	242
Total assets	228,278	108,417
Current liabilities:
Accounts payable	3,291	2,292
Accrued expenses and other current liabilities	12,361	18,267
Current portion of note payable, net of discount	4,906
Total current liabilities	20,558	20,559
Note payable, net of current portion and discount	19,624	24,394
Total liabilities	$ 40,182	$ 44,953
Commitments and contingencies
Stockholders' equity:
Common stock, $.0001 par value; 200,000,000 shares authorized, 37,936,611 shares and 32,924,535 shares issued and outstanding at June 30, 2015 and December 31, 2014, respectively	$ 4	$ 3
Additional paid-in-capital	572,342	407,720
Accumulated other comprehensive income (loss)	10	(21)
Accumulated deficit	(384,260)	(344,238)
Total stockholders' equity	188,096	63,464
Total liabilities and stockholders' equity	$ 228,278	$ 108,417