Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 78,219	$ 31,569
Marketable securities	102,995	184,320
Prepaid expenses and other, current	8,143	7,660
Total current assets	189,357	223,549
Property and equipment, net	2,219	2,383
Prepaid expenses and other, long-term	9,284	9,597
Restricted cash	4,314	4,313
Total assets	205,174	239,842
Current liabilities:
Accounts payable	24,837	17,803
Accrued expenses	14,068	14,639
Total current liabilities	38,905	32,442
Deferred rent	1,326	1,393
Total liabilities	$ 40,231	$ 33,835
Commitments and contingencies (Note 8 - Subsequent Events)
Stockholders' equity:
Common stock - $.0001 par value; 100,000,000 shares authorized; 32,493,092 shares issued and outstanding at March 31, 2016 and 32,466,842 issued and outstanding at December 31, 2015	$ 3	$ 3
Additional paid-in capital	756,383	726,651
Accumulated other comprehensive income (loss)	29	(147)
Accumulated deficit	(591,472)	(520,500)
Total stockholders' equity	164,943	206,007
Total liabilities and stockholders' equity	$ 205,174	$ 239,842