CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 51,490	$ 59,522
Marketable securities	86,431	0
Accounts and other receivables	1,970	2,218
Prepaid expenses and other current assets	13,432	12,610
Total current assets	153,323	74,350
Property and equipment, net	444	209
Long-term deposits	9,658	12,571
Other assets, net	12,095	9,000
Total assets	175,520	96,130
Current liabilities:
Accounts payable	2	149
Accrued compensation	555	1,001
Other current liabilities	11,247	2,457
Deferred revenue	4,826	5,173
Total current liabilities	16,630	8,780
Long-term deferred revenue	16,699	21,334
Other long-term liabilities	896	2,035
Total liabilities	34,225	32,149
Commitments and contingencies (Note 5)
Stockholders’ equity:
Common stock and additional paid-in capital – $0.001 par value; 100,000,000 shares authorized; 46,534,198 and 39,161,214 shares issued, respectively; 34,390,765 and 27,017,781 shares outstanding, respectively	323,296	258,756
Accumulated other comprehensive income	412	122
Accumulated deficit	(100,680)	(113,164)
Treasury stock at cost: 12,143,433 and 12,143,433 shares, respectively	(81,733)	(81,733)
Total stockholders’ equity	141,295	63,981
Total liabilities and stockholders’ equity	$ 175,520	$ 96,130