Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 46,687	$ 86,508
Short-term investments	66,129	39,000
Prepaid expenses and other current assets	1,405	1,567
Total current assets	114,221	127,075
Right-of-use asset	228	394
Other assets	204	45
Total assets	114,653	127,514
Current liabilities:
Accounts payable	931	1,557
Accrued expenses	3,852	3,281
Current portion of operating lease liabilities	184	365
Total current liabilities	4,967	5,203
Total liabilities	4,967	5,203
Commitments (Note 7)
Stockholders' equity:
Common stock, $0.001 par value per share, 150,000,000 shares authorized; 13,016,955 shares issued and outstanding at March 31, 2021 and December 31, 2021, respectively	13	13
Additional paid-in capital	484,460	481,709
Accumulated other comprehensive loss	(53)
Accumulated deficit	(471,132)	(455,809)
Total stockholders' equity	109,686	122,311
Total liabilities and stockholders' equity	114,653	127,514
Preferred shares
Stockholders' equity:
Preferred stock
Series X redeemable convertible preferred stock
Stockholders' equity:
Preferred stock	$ 96,398	$ 96,398