Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net loss	$ (51,172)	$ (47,563)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation	393	239
Loss on disposal of property and equipment	618
Non-cash interest expense, and amortization of debt discount and issuance costs	48	102
Amortization of premiums / (accretion of discounts), net on marketable securities	651	83
Stock-based compensation	5,364	4,018
Changes in assets and liabilities
Prepaid expenses and other assets	(946)	1,455
Accounts payable	(1,212)	(1,625)
Accrued and other current liabilities	3,268	974
Other non-current liabilities	(9)	(10)
Net cash used in operating activities	(42,997)	(42,327)
Cash flows from investing activities
Purchases of marketable securities	(88,620)	(34,008)
Proceeds from maturities of marketable securities	39,873	97,172
Purchases of property and equipment	(2,030)	(5,165)
Net cash (used in) provided by investing activities	(50,777)	57,999
Cash flows from financing activities
Repayment of debt	(2,000)	(2,000)
Proceeds from private placement financing, net of issuance costs	75,215
Payment of offering costs		(235)
Proceeds from issuance of common stock under employee plans	68	134
Net cash provided by (used in) financing activities	73,283	(2,101)
Net (decrease) increase in cash and cash equivalents	(20,491)	13,571
Cash and cash equivalents
Cash and cash equivalents, at beginning of period	36,326	22,755
Cash and cash equivalents, at end of period	15,835	36,326
Supplemental disclosure of cash flow information:
Cash paid for income taxes	5
Cash paid for interest	126	259
Supplemental non-cash investing and financing activities:
Purchases of property and equipment in accounts payable and accrued and other current liabilities	$ 24	$ 724