BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 91,725	$ 115,069
Receivables	1,510	4,665
Prepaid expenses and other current assets	3,319	10,855
Total current assets	96,554	130,589
Property and equipment, net	11,662	10,231
Right of use asset	5,179	4,650
Deposits	365	130
Other non-current assets	2	745
Total assets	113,762	146,345
Current liabilities:
Accounts payable	1,463	960
Current portion of long-term debt	12,037	0
Accrued expenses	13,963	16,589
Lease liability - current portion	710	819
Total current liabilities	28,173	18,368
Long-term debt	12,174	0
Lease liability - non-current portion	4,708	3,995
Total liabilities	45,055	22,363
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock, $0.001 par value; 350,000,000 shares authorized; 216,145,804 and 214,591,906 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	216	215
Additional paid-in capital	899,549	887,868
Accumulated deficit	(831,058)	(764,101)
Total stockholders' equity	68,707	123,982
Total liabilities and stockholders' equity	$ 113,762	$ 146,345