CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net loss	$ (48,069)	$ (34,797)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of intangible assets	73	73
Depreciation and amortization	1,139	1,278
Amortization of premium (accretion of discounts) on investments	(33)	281
Stock-based compensation expense	7,860	6,459
Non-cash lease expense	1,670	1,534
Changes in operating assets and liabilities
Accounts receivable	(290)	(133)
Prepaid expenses and other current assets	694	3,199
Other assets	6	1,271
Accounts payable	(844)	(1,173)
Accrued liabilities and other long-term liabilities	(4,484)	(5,559)
Deferred revenue	(33,272)	(30,572)
Net cash used in operating activities	(75,550)	(58,139)
Cash flows from investing activities:
Purchases of property and equipment	(1,148)	(1,096)
Purchases of investments	0	(99,898)
Maturities of investments	0	113,994
Net cash provided by (used in) investing Activities	(1,148)	13,000
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs	0	107,712
Proceeds from employee stock purchase plan and exercise of stock options	458	1,714
Net cash provided by financing activities	458	109,426
Net increase (decrease) in cash, cash equivalents and restricted cash	(76,240)	64,287
Cash, cash equivalents and restricted cash, beginning of period	206,447	192,776
Cash, cash equivalents and restricted cash, end of period	130,207	257,063
Supplemental disclosures of noncash investing items:
Purchases of property and equipment in accounts payable and accrued liabilities	$ 29	$ 54