CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 138,218	$ 193,018
Marketable securities	392,990	372,670
Prepaid expenses and other current assets	8,933	12,329
Total current assets	540,141	578,017
Marketable securities		52,269
Property and equipment, net	29,314	28,449
Operating lease assets	22,573	23,251
Restricted cash	1,867	4,200
Other long-term assets	2,762	2,733
Total assets	596,657	688,919
Current liabilities:
Accounts payable	11,008	11,298
Accrued expenses and other current liabilities	43,063	28,803
Operating lease liabilities, current portion	2,672	2,437
Total current liabilities	56,743	42,538
Operating lease liabilities, net of current portion	32,688	34,110
Financing liability, related party (Notes 5 and 6)	27,205	16,770
Financing liability (Notes 5 and 6)	27,205	16,770
Other long-term liabilities	2	2
Total liabilities	143,843	110,190
Commitments and contingencies (Notes 12 and 13)
Stockholders’ equity:
Preferred stock, $0.0001 par value: 10,000,000 shares authorized; no shares issued and outstanding as of June 30, 2022 and December 31, 2021
Common stock, $0.0001 par value: 500,000,000 shares authorized; 148,395,282 and 147,719,523 shares issued and outstanding as of June 30, 2022 and December 31, 2021, respectively	15	15
Additional paid-in capital	1,219,820	1,195,944
Accumulated other comprehensive income (loss)	7,988	(986)
Accumulated deficit	(775,009)	(616,244)
Total stockholders’ equity	452,814	578,729
Total liabilities and stockholders’ equity	$ 596,657	$ 688,919