Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 92,892	$ 67,737
Other receivable	5,010
Prepaid expenses and other current assets	856	475
Total current assets	98,758	68,212
Other assets	90	90
Total assets	98,848	68,302
Current liabilities:
Accounts payable	43,412	15,366
Accrued expenses	5,698	3,175
Deferred revenue	4,145	1,874
Total current liabilities	53,255	20,415
Non-current liabilities:
Deferred revenue	4,126	2,342
Long-term debt	24,444
Total liabilities	81,825	22,757
Stockholders' equity:
Common stock, $0.001 par value: 225,000,000 shares authorized at March 31, 2021 and December 31, 2020; 53,656,689 and 51,626,508 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	54	52
Additional paid-in capital	456,966	419,923
Accumulated deficit	(439,997)	(374,430)
Total stockholders' equity	17,023	45,545
Total liabilities and stockholders' equity	$ 98,848	$ 68,302