CONDENSED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 62,608	$ 96,692
Short-term investments, available-for-sale	236,655	218,221
Prepaid expenses and other current assets	2,971	3,922
Total current assets	302,234	318,835
Restricted cash	413	413
Property and equipment, net	10,498	9,350
Operating lease right-of-use assets	11,873	8,505
Other long-term assets	674	547
Total assets	325,692	337,650
Current liabilities
Accounts payable	2,010	1,176
Operating lease liabilities, current portion	2,151	1,402
Accrued and other current liabilities	5,192	6,253
Total current liabilities	9,353	8,831
Operating lease liabilities, net of current portion	10,274	7,517
Other long-term liabilities	75	82
Total liabilities	19,702	16,430
Commitments and contingencies (Note 7)
Stockholders’ equity
Preferred stock
Common stock	3	3
Additional paid-in capital	443,347	439,235
Accumulated other comprehensive income	34	3
Accumulated deficit	(137,394)	(118,021)
Total stockholders’ equity	305,990	321,220
Total liabilities and stockholders’ equity	$ 325,692	$ 337,650