Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 113,437	$ 114,057
Marketable securities	3,997	13,998
Accounts receivable	7,153	9,914
Prepaid expenses and other current assets	5,420	6,474
Total current assets	130,007	144,443
Property and equipment, net	2,689	2,142
Right-of-use asset, net	9,536	9,829
Long-term restricted cash	1,379	1,379
Investments	2,000	2,000
Other assets	85	90
Total assets	145,696	159,883
Current liabilities:
Accounts payable	264	224
Accrued expenses	8,889	10,533
Loan payable	696	5,961
Lease liability	1,087	1,049
Income taxes payable	320	601
Deferred revenue	27,990	53,883
Total current liabilities	39,246	72,251
Non-current liabilities:
Loan payable, net of current portion	25,042	19,673
Lease liability	8,316	8,598
Deferred revenue	10,420	11,417
Warrant liabilities	6,908	25,423
Total liabilities	89,932	137,362
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized; no shares issued and outstanding at March 31, 2022 and December 31, 2021	0	0
Common stock, $0.0001 par value; 200,000,000 shares authorized; 124,380,844 and 123,622,965 shares issued and outstanding as of March 31, 2022 and December 31, 2021, respectively	12	12
Additional paid-in capital	461,888	457,391
Accumulated deficit	(401,538)	(430,316)
Accumulated other comprehensive loss	(4,598)	(4,566)
Total stockholders’ equity	55,764	22,521
Total liabilities and stockholders’ equity	$ 145,696	$ 159,883