CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Current assets:    
Cash and cash equivalents $ 225,848 $ 91,165
Investments 0 85,122
Prepaid expenses and other current assets 3,975 5,224
Total current assets 229,823 181,511
Operating lease, right-of-use-asset 35,095 40,447
Property, plant and equipment, net 51,530 53,952
Restricted cash 1,573 1,573
Other assets   311
Total assets 318,021 277,794
Current liabilities:    
Accounts payable 11,572 5,478
Accrued expenses and other current liabilities 14,072 13,417
Operating lease liabilities 9,015 8,945
Total current liabilities 34,659 27,840
Long-term debt, net of discount 76,154 74,944
Other long-term liabilities 135 688
Operating lease liabilities, net of current portion 28,291 32,762
Total liabilities 139,239 136,234
Commitments and contingencies (see Note 10)
Stockholders' equity:    
Preferred stock, $0.001 par value; 10,000,000 shares authorized at December 31, 2021 and December 31, 2020; no shares issued or outstanding at December 31, 2021 and December 31, 2020
Common stock, $0.001 par value; 150,000,000 shares authorized at December 31, 2021 and December 31, 2020; 90,063,770 and 81,053,651 shares issued and outstanding at December 31, 2021 and December 31, 2020, respectively 90 81
Additional paid-in capital 855,710 621,946
Accumulated other comprehensive income   4
Accumulated deficit (677,018) (480,471)
Total stockholders' equity 178,782 141,560
Total liabilities and stockholders' equity $ 318,021 $ 277,794