CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 46,928	$ 71,976
Short-term investments	186,452	235,328
Prepaid expenses and other current assets	8,247	6,446
Total current assets	241,627	313,750
Property and equipment, net	6,398	6,356
Operating lease right-of-use assets	1,927
Restricted cash	210	210
Deferred offering costs	0	433
Deferred tax assets	4,372	1,216
Total assets	254,534	321,965
Current liabilities:
Accounts payable	5,693	10,918
Accrued expenses	20,415	16,418
Accrued milestones		15,000
Operating lease liabilities	1,697
Other current liabilities	25	218
Total current liabilities	27,830	42,554
Noncurrent liabilities:
Noncurrent operating lease liabilities	955
Other long-term liabilities	326	144
Total liabilities	29,111	42,698
Commitments and contingencies (Note 13)
Shareholders’ equity:
Additional paid-in capital	581,467	473,483
Accumulated other comprehensive income (loss)	33	(4)
Accumulated deficit	(356,092)	(194,225)
Total shareholders’ equity	225,423	279,267
Total liabilities and shareholders’ equity	254,534	321,965
Class A common shares
Shareholders’ equity:
Common stock value	6	4
Class B common shares
Shareholders’ equity:
Common stock value	1	1
Class A1 common shares
Shareholders’ equity:
Common stock value	4	4
Class B1 common shares
Shareholders’ equity:
Common stock value	$ 4	$ 4