Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 46,842	$ 14,280
Restricted cash	215	540
Accounts receivable, net	4,633	5,063
Prepaid expenses and other current assets	2,324	3,039
Total current assets	54,014	22,922
Property and equipment, net	3,622	5,477
Right-of-use assets, operating leases	1,660	7,737
Other non-current assets	535	873
Total assets	59,831	37,009
Current liabilities:
Accounts payable	975	928
Accrued expenses and other current liabilities	6,176	6,552
Note payable, current	2,226	1,854
Operating lease liabilities	2,006	6,800
Total current liabilities	11,383	16,134
Note payable, net of current	1,094	1,466
Operating lease liabilities, non-current	0	1,814
Other long-term liabilities	1,096	1,780
Total liabilities	13,573	21,194
Commitments and contingencies (Note 15)
Stockholders' equity:
Common stock, $0.001 par value - 142,857 shares authorized, 15,532 and 9743 shares issued and outstanding at December 31, 2021 and 2020, respectively	15	10
Additional paid-in capital	351,394	308,065
Accumulated deficit	(304,107)	(291,163)
Accumulated other comprehensive loss	(1,044)	(1,097)
Total stockholders' equity	46,258	15,815
Total liabilities and stockholders' equity	$ 59,831	$ 37,009