Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash, cash equivalents and restricted cash	$ 48,434	$ 46,013
Short-term investments	23,377	49,704
Accounts receivable	264	20
Prepaid expenses and other current assets	3,755	3,714
Total current assets	75,830	99,451
Property and equipment, net	14,373	15,585
Right-of-use assets, net	27,843	25,715
Intangible assets, net	4,837	5,020
Goodwill	4,508	4,508
Other long-term assets	2,460	3,568
Total assets	129,851	153,847
Current liabilities:
Accounts payable	3,882	5,514
Deferred grant revenue	1,603	2,000
Other accrued current liabilities	6,977	8,084
Current portion of operating lease liability	2,344	2,228
Current portion of liability related to sale of future royalties	877	95
Total current liabilities	15,683	17,921
Operating lease liability, net of current portion	19,172	19,477
Liability related to sale of future royalties, net of current portion	4,997	5,621
Other long-term liabilities	246	231
Total liabilities	40,098	43,250
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock: $0.0001 par value; 5,000,000 shares authorized; none issued and outstanding as of March 31, 2023 and December 31, 2022	0	0
Common stock: $0.0001 par value; 250,000,000 shares authorized as of March 31, 2023 and December 31, 2022, respectively; 135,610,869 shares issued and 135,597,316 shares outstanding as of March 31, 2023 and 134,199,429 shares issued and outstanding as of December 31, 2022.	14	13
Additional paid-in capital	442,068	437,992
Treasury stock at cost, 13,553 shares and none as of March 31, 2023 and December 31, 2022, respectively	(10)	0
Accumulated deficit	(352,249)	(327,109)
Accumulated other comprehensive loss	(70)	(299)
Total stockholders’ equity	89,753	110,597
Total liabilities and stockholders’ equity	$ 129,851	$ 153,847