Condensed Consolidated Balance Sheets - USD ($) $ in Thousands		Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents		$ 94,841	$ 163,030
Short term investments		11,703	18,311
Prepaid expenses and other current assets		9,537	13,423
Total current assets		116,081	194,764
Property and equipment, net		24,306	22,985
Operating lease assets		108,914	110,984
Restricted cash		8,185	8,185
Restricted investments		1,401	1,401
Other non-current assets		11,307	10,465
Total assets		270,194	348,784
Current liabilities:
Accounts payable		12,297	17,440
Accrued expenses and other current liabilities	[1]	44,361	59,840
Operating lease liabilities		4,784	3,601
Short term portion of note payable, net of discount		0	456
Deferred revenue - related party		2,376	4,259
Total current liabilities		63,818	85,596
Long term portion of note payable, net of discount		51,234	50,591
Operating lease liabilities, net of current portion		106,692	107,942
Deferred revenue, net of current portion - related party		94,835	92,430
Other long-term liabilities		1,486	1,442
Total liabilities		318,065	338,001
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized at March 31, 2023 and December 31, 2022; no shares issued and outstanding at March 31, 2023 and December 31, 2022		0	0
Common stock, $0.001 par value; 200,000,000 shares authorized at March 31, 2023 and December 31, 2022; 126,592,604 and 125,222,273 shares issued and outstanding at March 31, 2023 and December 31, 2022, respectively		127	125
Additional paid-in capital		887,685	875,181
Accumulated other comprehensive loss		2	(12)
Accumulated deficit		(935,685)	(864,511)
Total stockholders' (deficit) equity		(47,871)	10,783
Total liabilities and stockholders' (deficit) equity		$ 270,194	$ 348,784

[1] Includes related party amounts of $24,958 and $34,770 at March 31, 2023 and December 31, 2022, respectively (see Note 11)