Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net loss	$ (17,610)	$ (24,697)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	3,310	2,530
Loss on disposal of fixed asset		5
Depreciation expense	163	150
Amortization of premium on marketable securities	(3)	(11)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	287	1,908
Accounts payable	(1,235)	(1,466)
Accrued expenses	64	(168)
Right-of-use assets	272	263
Operating lease liabilities	(287)	(249)
Other assets	20	(253)
Net cash used in operating activities:	(15,019)	(21,988)
Cash flows from investing activities:
Purchase of property and equipment	(100)	(31)
Purchase of marketable debt securities	(35,242)	(1,749)
Maturities and sales of marketable debt securities		26,250
Net cash provided by (used in) investing activities	(35,342)	24,470
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash	(50,361)	2,482
Cash, cash equivalents and restricted cash at beginning of period	71,436	69,487
Cash, cash equivalents and restricted cash at end of period	$ 21,075	71,969
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment included in accounts payable and accrued expenses		$ 295