CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 84,903	$ 31,004
Marketable securities (Note 4)	274,204	265,198
Accounts receivable—due from related parties		577
Contract assets—due from related parties	904	856
Prepaid expenses and other current assets	4,795	4,704
Total current assets	364,806	302,339
Marketable securities, non-current (Note 4)	45,305	162,531
Property and equipment, net (Note 6)	12,118	10,841
Right-of-use assets, operating leases	9,648	9,845
Other non-current assets	920	30
Restricted cash	1,589	1,589
Total assets	434,386	487,175
Current liabilities:
Accounts payable	8,177	4,368
Accrued expenses (Note 8)	14,668	10,330
Deferred revenue	82,263	92,552
Operating lease liabilities	2,425	2,572
Finance lease liabilities	1,038	689
Other current liabilities	114	106
Total current liabilities	108,685	110,617
Non-current liabilities
Deferred revenue, net of current portion	52,672	77,838
Operating lease liabilities, net of current portion	13,696	14,128
Finance lease liabilities, net of current portion	1,145	604
Other non-current liabilities	84	100
Total liabilities	176,282	203,287
Stockholders’ equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized as of June 30, 2021 and December 31, 2020; 0 shares issued or outstanding as of June 30, 2021 and December 31, 2020
Common stock, $0.0001 par value; 150,000,000 shares authorized at June 30, 2021 and December 31, 2020, 45,401,203 and 44,592,288 shares issued at June 30, 2021 and December 31, 2020, respectively; 45,327,681 and 44,482,186 shares outstanding at June 30, 2021 and December 31, 2020, respectively	5	4
Additional paid-in capital	424,599	412,777
Accumulated deficit	(166,500)	(128,765)
Accumulated other comprehensive loss		(128)
Total stockholders’ equity	258,104	283,888
Total liabilities and stockholders’ equity	$ 434,386	$ 487,175

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).