CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 114,038	$ 46,928
Restricted cash	210
Short-term investments	209,444	186,452
Prepaid expenses and other current assets	9,557	8,247
Total current assets	333,249	241,627
Property and equipment, net	4,051	6,398
Operating lease right-of-use assets	6,566	1,927
Restricted cash		210
Other long-term assets	5,588
Deferred offering costs	0	0
Deferred tax assets	10	4,372
Total assets	349,464	254,534
Current liabilities:
Accounts payable	503	5,693
Accrued expenses	29,199	20,415
Operating lease liabilities	2,107	1,697
Other current liabilities	37	25
Total current liabilities	31,846	27,830
Non-current liabilities:
Non-current operating lease liabilities	4,878	955
Other long-term liabilities	805	326
Total liabilities	37,529	29,111
Commitments and contingencies (Note 12)
Shareholders' equity:
Additional paid-in capital	829,424	581,467
Accumulated other comprehensive income	(34)	33
Accumulated deficit	(517,473)	(356,092)
Total shareholders' equity	311,935	225,423
Total liabilities and shareholders' equity	349,464	254,534
Class A common shares
Shareholders' equity:
Common stock value	8	6
Class B common shares
Shareholders' equity:
Common stock value	1	1
Class A1 common shares
Shareholders' equity:
Common stock value	5	4
Class B1 common shares
Shareholders' equity:
Common stock value	$ 4	$ 4