BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 140,717	$ 42,803
Receivables	446	145
Prepaid expenses and other current assets	11,358	1,139
Total current assets	152,521	44,087
Property and equipment, net	581	531
Deposits	128	128
Other non current assets	494	491
Total assets	153,724	45,237
Current liabilities:
Accounts payable	2,008	2,004
Accrued expenses	8,906	7,182
Deferred revenue - current portion	6,861	1,360
Deferred rent - current portion	348	280
Total current liabilities	18,123	10,826
Deferred revenue, net of current position	47,917
Deferred rent, net of current position	313	570
Total liabilities	$ 66,353	$ 11,396
Commitments and contingencies (note 8)
Stockholders' equity:
Common stock, $0.001 par value; 250,000,000 shares authorized; 131,718,579 and 104,452,105 shares issued and outstanding at December 31, 2015 and 2014, respectively	$ 132	$ 104
Additional paid-in capital - common stock	579,939	406,349
Accumulated Deficit	(492,700)	(372,612)
Total stockholders' equity	87,371	33,841
Total liabilities and stockholders' equity	$ 153,724	$ 45,237