Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 39,446	$ 34,479
Marketable securities	47,789
Prepaid expenses	1,527	840
Total current assets	88,762	35,319
Property and equipment, net	14,208	14,044
Right of use and other assets	94	177
Total assets	103,064	49,540
Current liabilities:
Accounts payable	5,121	1,819
Accrued expenses	1,290	1,804
Lease liability, current portion	82	172
Total current liabilities	6,493	3,795
Long-term debt	15,775
Total liabilities	22,268	3,795
Commitments and contingencies (Note 13)
Stockholders' equity
Common stock, $.0001 par value, 150,000,000 shares authorized, 87,297,605 and 69,810,305 issued and outstanding at June 30, 2020 and December 31, 2019, respectively	9	7
Additional paid-in capital	359,856	306,108
Accumulated other comprehensive income	10
Accumulated deficit	(279,079)	(260,370)
Total stockholders’ equity	80,796	45,745
Total liabilities and stockholders’ equity	$ 103,064	$ 49,540