Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 200,609	$ 154,744
Available-for-sale securities	48,350
Prepaid expenses and other current assets	5,743	4,157
Restricted cash, current	90	0
Accounts receivable - related party	286
Total current assets	255,078	158,901
Property and equipment, net	7,128	8,153
Operating lease, right-of-use assets	1,581	3,579
Other non-current assets		209
Restricted cash, excluding current portion	2,070	327
Total assets	265,857	171,169
Current liabilities:
Accounts payable	3,003	3,274
Accrued expenses	7,714	8,640
Operating lease liabilities	1,499	1,999
Finance lease liabilities	220	208
Other current liabilities	61
Deferred revenue - related party	10,048	10,359
Total current liabilities	22,545	24,480
Operating lease liabilities, excluding current portion	656	2,419
Finance lease liabilities, excluding current portion	412	525
Deferred revenue - related party, excluding current portion	4,306	10,359
Other non-current liabilities		1,300
Total liabilities	27,919	39,083
Commitments and contingencies
Preferred stock, $0.001 par value; 10,000,000 shares authorized at June 30, 2021 and December 31, 2020; no shares issued and outstanding at June 30, 2021 and December 31, 2020
Common stock, $0.001 par value; 300,000,000 shares authorized at June 30, 2021 and December 31, 2020; 110,295,992 shares issued and outstanding at June 30, 2021 and 84,893,994 shares issued and outstanding at December 31, 2020; 2,158,329 pre-funded warrants outstanding at June 30, 2021 and December 31, 2020	112	87
Additional paid-in capital	678,001	536,568
Accumulated other comprehensive loss	(11)
Accumulated deficit	(440,164)	(404,569)
Total stockholders’ equity	237,938	132,086
Total liabilities and stockholders’ equity	$ 265,857	$ 171,169