Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 29,988	$ 35,042
Prepaid expenses and other current assets	3,018	2,207
Total current assets	33,006	37,249
Property and equipment, net	1,173	881
Operating lease assets	455	678
Other assets	123	123
Total assets	34,757	38,931
Current liabilities:
Accounts payable	1,030	2,410
Loan payable, net of discount	9,852
Accrued expenses and other current liabilities	4,480	3,421
Operating lease liabilities	317	291
Total current liabilities	15,679	6,122
Loan payable, net of current portion and discount		9,853
Operating lease liabilities, net of current portion	210	387
Total liabilities	15,889	16,362
Commitments and contingencies (Note 7)
Stockholders’ equity:
Undesignated preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.001 par value; 200,000,000 and 125,000,000 shares authorized at December 31, 2021 and 2020, respectively; 82,969,421 and 50,821,361 shares issued and outstanding at December 31, 2021 and 2020, respectively	83	51
Additional paid-in capital	265,237	220,307
Accumulated deficit	(246,452)	(197,789)
Total stockholders’ equity	18,868	22,569
Total liabilities and stockholders’ equity	$ 34,757	$ 38,931