CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 56,494	$ 76,938
Prepaid manufacturing services	7,308	7,315
Prepaid expenses and other current assets	6,111	5,918
Total current assets	69,913	90,171
Property and equipment, net of accumulated depreciation of $12,887 and $11,809	22,456	23,479
Restricted cash	4,170	4,170
Operating right-of-use assets	21,638	21,957
Prepaid manufacturing services, net of current portion	31,893	31,893
Total assets	150,070	171,670
Current liabilities:
Accounts payable	1,516	1,838
Accrued expenses	6,808	9,703
Deferred revenue	442	12,963
Operating lease liabilities	2,775	2,661
Total current liabilities	11,541	27,165
Long-term liabilities:
Deferred revenue, net of current portion	30,503	30,686
Note payable, net of discount	25,514	25,430
Operating lease liabilities, net of current portion	34,133	34,884
Total liabilities	101,691	118,165
Commitments and contingencies (Note 9)
Stockholders' equity:
Common stock, $0.0001 par value; 150,000,000 shares authorized as of March 31, 2022 and December 31, 2021; 22,493,867 and 22,383,830 shares issued and outstanding as of March 31, 2022 and December 31, 2021, respectively	2	2
Additional paid-in capital	381,652	378,750
Accumulated deficit	(333,275)	(325,247)
Total stockholders' equity	48,379	53,505
Total liabilities and stockholders' equity	$ 150,070	$ 171,670