BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 28,122	$ 74,025
Other receivables	0	1,233
Prepaid expenses and other assets	12,027	3,565
Total current assets	40,149	78,823
Property and equipment, net	8,224	1,924
Operating lease right-of-use assets	1,927	1,715
Other assets	57	32
Total assets	50,357	82,494
Current liabilities:
Current portion of long-term debt	5,355	2,378
Accounts payable	3,674	2,921
Accrued expenses and other current liabilities	5,931	3,180
Total current liabilities	14,960	8,479
Long-term debt, net	6,773	12,326
Operating lease liabilities, net	1,548	1,508
Development derivative liability	51,719	0
Other long-term liabilities	559	203
Total liabilities	75,559	22,516
Commitments and contingencies (Note 8)
Stockholders’ (deficit) equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized; zero shares issued and outstanding at December 31, 2020 and 2019	0	0
Common stock, $0.001 par value; 200,000,000 shares authorized; 29,471,854 shares issued and 29,441,887 shares outstanding at December 31, 2020; 28,796,371 shares issued and 28,766,404 shares outstanding at December 31, 2019	29	29
Treasury stock, at cost, 29,967 shares as of December 31, 2020 and 2019	(24)	(24)
Additional paid-in capital	235,516	222,131
Accumulated deficit	(260,723)	(162,158)
Total stockholders’ (deficit) equity	(25,202)	59,978
Total liabilities and stockholders' (deficit) equity	$ 50,357	$ 82,494
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent