Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 59,424	$ 60,541
Prepaid expenses and other current assets	3,321	1,148
Total current assets	62,745	61,689
Restricted cash	2,431	2,430
Property and equipment, net	400	526
Operating lease right-of-use assets	2,207	2,958
Intangible asset, net	0	97
Other assets	4	10
Total assets	67,787	67,710
Current liabilities
Accounts payable	2,657	2,500
Accrued liabilities	8,416	2,323
Operating lease obligation, current portion	2,297	2,086
Current portion of deferred revenue	4,571	2,552
Total current liabilities	17,941	9,461
Deferred revenue, net of current portion	3,548	3,763
Operating lease obligation, net of current portion	4,076	6,431
Total liabilities	25,565	19,655
Commitments and contingencies (Note 7)
Stockholders' equity
Common stock, $0.0001 par value, 100,000,000 shares authorized at December 31, 2021 and December 31, 2020; 21,039,594 and 16,481,099 shares issued and outstanding at December 31, 2021 and December 31, 2020, respectively	2	2
Additional paid-in capital	582,025	548,707
Accumulated deficit	(539,805)	(500,654)
Total stockholders' equity	42,222	48,055
Total liabilities and stockholders’ equity	$ 67,787	$ 67,710