Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents		$ 180,002	$ 116,049
Short term investments		110,704	137,567
Prepaid expenses and other current assets		12,922	5,774
Accounts receivable			9,387
Total current assets		303,628	268,777
Property and equipment, net		17,938	13,897
Operating lease assets		18,208	9,041
Restricted cash		8,000	0
Restricted investments		1,401	1,400
Long term investments		495	49,825
Other non-current assets		5,189
Total assets		354,859	342,940
Current liabilities:
Accounts payable		13,735	4,018
Accrued expenses and other current liabilities	[1]	45,094	14,226
Operating lease liabilities		6,610	5,115
Short term portion of note payable, net of discount			454
Deferred revenue - related party		16,819	22,602
Total current liabilities		82,258	46,415
Long term portion of note payable, net of discount		24,643	24,639
Operating lease liabilities, net of current portion		17,958	10,561
Deferred revenue, net of current portion - related party		86,998	85,572
Other long-term liabilities	[2]	11,495	1,003
Total liabilities		223,352	168,190
Commitments and contingencies (Note 14)
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value; 10,000,000 shares authorized at December 31, 2021 and 2020; no shares issued and outstanding at December 31, 2021 and 2020
Common stock, $0.001 par value; 200,000,000 shares authorized at December 31, 2021 and 2020; 91,889,418 and 91,459,239 shares issued and outstanding at December 31, 2021 and 2020		92	91
Additional paid-in capital		745,829	723,482
Accumulated other comprehensive loss		(60)	(47)
Accumulated deficit		(614,354)	(548,776)
Total stockholders' equity		131,507	174,750
Total liabilities and stockholders' equity		$ 354,859	$ 342,940

[1] Includes related party amounts of $21,098 and $0 at December 31, 2021 and December 31, 2020, respectively (see Note 12)

[2] Includes related party amounts of $10,585 and $0 at December 31, 2021 and December 31, 2020, respectively (see Note 12)