Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows used in operating activities:
Net loss	$ (19,294)	$ (26,247)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	3,821	5,738
Operating lease right-of-use asset	683	401
Depreciation	109	87
Amortization of premium on marketable debt securities	756	747
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(716)	(1,848)
Other assets	54	144
Accounts payable	(562)	489
Accrued expenses	(272)	(475)
Operating lease liabilities	(663)	(430)
Net cash used in operating activities	(16,084)	(21,394)
Cash flows from investing activities:
Purchase of marketable debt securities	(14,428)	(99,574)
Proceeds from maturity and redemption of marketable debt securities	28,706
Purchase of property and equipment	(31)	(616)
Net cash provided by/(used in) investing activities	14,247	(100,190)
Cash flows from financing activities:
Repurchase of shares in connection with settlement of RSUs	(72)	(228)
Net cash used in financing activities	(72)	(228)
Net decrease in cash and cash equivalents and restricted cash	(1,909)	(121,812)
Cash and cash equivalents and restricted cash - beginning of year	36,469	169,393
Cash and cash equivalents and restricted cash - end of period	34,560	47,581
Reconciliation of cash and cash equivalents and restricted cash to the condensed consolidated balance sheets:
Cash and cash equivalents	33,815	46,836
Restricted cash
Restricted cash, non-current	745	745
Cash and cash equivalents and restricted cash	$ 34,560	$ 47,581