Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 117,799	$ 104,440
Marketable securities	43,707	76,698
Related party collaboration receivable	4,253	8,012
Prepaid expenses and other current assets	10,078	8,619
Total current assets	175,837	197,769
Property and equipment, net	24,520	25,435
Deposits and other non-current assets	2,247	2,316
Operating lease, right-of-use assets	35,113	36,064
Total assets	237,717	261,584
Current liabilities:
Accounts payable	3,177	634
Accrued expenses	10,535	14,205
Other current liabilities	4,596	4,198
Deferred revenue, current	6,443	7,729
Total current liabilities	24,751	26,766
Deferred revenue, non-current	33,614	36,088
Other non-current liabilities	43,144	44,410
Total liabilities	101,509	107,264
Commitments and contingencies (see note 8)
Stockholders' equity:
Preferred stock $0.001 par value: 5,000,000 shares authorized at March 31, 2021 and December 31, 2020; no shares issued and outstanding at March 31, 2021 and December 31, 2020
Common stock, $0.001 par value: 120,000,000 shares authorized at March 31, 2021 and December 31, 2020; 37,556,055 and 37,368,027 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	38	37
Additional paid-in capital	433,849	430,324
Accumulated other comprehensive loss	(123)	(134)
Accumulated deficit	(297,556)	(275,907)
Total stockholders' equity	136,208	154,320
Total liabilities and stockholders' equity	$ 237,717	$ 261,584