CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 90,601	$ 59,522
Marketable Securities, Current	28,028	0
Accounts and other receivables	4,171	2,218
Prepaid expenses and other current assets	11,739	12,610
Total current assets	134,539	74,350
Property and equipment, net	220	209
Deposits Assets, Noncurrent	11,928	12,571
Other assets	13,836	9,000
Total assets	160,523	96,130
Current liabilities:
Accounts payable	117	149
Accrued compensation	729	1,001
Other current liabilities	4,962	2,457
Deferred revenue	4,914	5,173
Total current liabilities	10,722	8,780
Long-term deferred revenue	17,859	21,334
Other long-term liabilities	1,153	2,035
Total liabilities	29,734	32,149
Contingencies (Note 5)
Stockholders’ equity:
Common stock and additional paid-in capital — $0.001 par value; 100,000,000 shares authorized; 45,167,893 and 39,161,214 shares issued, respectively; 33,024,460 and 27,017,781 shares outstanding, respectively	313,885	258,756
Accumulated other comprehensive income	653	122
Accumulated deficit	(102,016)	(113,164)
Treasury stock at cost: 12,143,433 and 12,143,433 shares, respectively	(81,733)	(81,733)
Total stockholders’ equity	130,789	63,981
Total liabilities and stockholders’ equity	$ 160,523	$ 96,130