CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 107,274	$ 59,522
Accounts and other receivables	2,912	2,218
Prepaid expenses and other current assets	11,942	12,610
Total current assets	122,128	74,350
Property and equipment, net	246	209
Deposits Assets, Noncurrent	12,353	12,571
Other assets	7,222	9,000
Total assets	141,949	96,130
Current liabilities:
Accounts payable	144	149
Accrued compensation	1,641	1,001
Other current liabilities	2,972	2,457
Deferred revenue	5,010	5,173
Total current liabilities	9,767	8,780
Long-term deferred revenue	19,021	21,334
Other long-term liabilities	1,435	2,035
Total liabilities	30,223	32,149
Contingencies (Note 5)
Stockholders’ equity:
Common stock and additional paid-in capital — $0.001 par value; 100,000,000 shares authorized; 43,252,670 and 39,161,214 shares issued, respectively; 31,109,237 and 27,017,781 shares outstanding, respectively	299,124	258,756
Accumulated other comprehensive income	122	122
Accumulated deficit	(105,787)	(113,164)
Treasury stock at cost: 12,143,433 and 12,143,433 shares, respectively	(81,733)	(81,733)
Total stockholders’ equity	111,726	63,981
Total liabilities and stockholders’ equity	$ 141,949	$ 96,130