CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 126,319	$ 122,927
Accounts receivable	2,489	2,629
Contract asset		557
Prepaid expenses and other current assets	6,263	5,565
Total current assets	135,071	131,678
Property and equipment, net	2,989	2,499
Other assets	2,750	2,663
Total assets	140,810	136,840
Current liabilities:
Accounts payable	4,671	3,126
Refund liability		21,233
Accrued expenses	14,865	16,207
Total current liabilities	19,536	40,566
Notes payable, net of deferred financing costs	69,927	40,809
Contract liability	9,113
Other long-term liabilities	1,829	1,979
Total liabilities	100,405	83,354
Stockholders' equity:
Series A convertible preferred stock, $0.001 par value; 25,000,000 shares authorized, 4,575 shares issued and outstanding at March 31, 2022 and December 31, 2021	4,302	4,302
Common stock, $0.001 par value; 150,000,000 shares authorized, 37,145,981 issued and 37,138,674 outstanding at March 31, 2022 and 36,797,561 issued and 36,790,254 outstanding at December 31, 2021	37	37
Additional paid-in capital	466,132	459,852
Treasury stock at cost, 7,307 shares at March 31, 2022 and December 31, 2021
Accumulated deficit	(430,066)	(410,705)
Total stockholders' equity	40,405	53,486
Total liabilities and stockholders' equity	$ 140,810	$ 136,840