Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 34,479	$ 7,851
Prepaid expenses	840	607
Total current assets	35,319	8,458
Property and equipment, net	14,044	13,916
Right of use and other assets	177	18
Total assets	49,540	22,392
Current liabilities:
Accounts payable	1,819	875
Accrued expenses	1,804	1,343
Lease payable, current portion	172
Total current liabilities	3,795	2,218
Total liabilities	3,795	2,218
Commitments and contingencies (Note 13)
Stockholders' equity
Common stock, $.0001 par value, 150,000,000 shares authorized, 69,810,305 and 34,377,329 issued and outstanding at December 31, 2019 and 2018, respectively	7	3
Additional paid-in capital	306,108	261,722
Accumulated deficit	(260,370)	(241,551)
Total stockholders' equity	45,745	20,174
Total liabilities and stockholders' equity	$ 49,540	$ 22,392