Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 13,634	$ 14,528
Marketable securities	196,318	115,608
Accounts receivable	831	8,616
Prepaid expenses and other current assets	7,027	2,901
Total current assets	217,810	141,653
Property and equipment, net	6,085	3,105
Patents, licenses, and other intangible assets, net	11,043	10,362
Marketable securities - long term	163,052	273,340
Other assets	265	103
Total assets	398,255	428,563
Current liabilities
Accounts payable	6,602	3,880
Accrued expenses	4,636	6,692
Current portion of deferred rent		128
Current portion of deferred revenue	89,088	95,521
Income taxes		65
Total current liabilities	100,326	106,286
Deferred rent, less current portion	1,202	397
Deferred revenue, less current portion	6,188	7,926
Total liabilities	107,716	114,609
Commitments and contingencies
Stockholders' equity
Preferred stock, $0.01 par value: 10,000,000 authorized shares; -0- issued and outstanding shares at September 30, 2017 and December 31, 2016
Common stock, $0.01 par value: 200,000,000 authorized shares at September 30, 2017 and December 31, 2016; 46,955,365 issued and outstanding at September 30, 2017 and 46,567,978 issued and outstanding at December 31, 2016	470	466
Additional paid-in capital	566,609	553,290
Accumulated other comprehensive loss	(1,097)	(1,441)
Accumulated deficit	(275,443)	(238,361)
Total stockholders' equity	290,539	313,954
Total liabilities and stockholders' equity	$ 398,255	$ 428,563