Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 65,371	$ 25,303
Prepaid expenses and other current assets	1,917	935
Total current assets	67,288	26,238
Property and equipment, net	2,829	3,751
Restricted cash	263	263
Other assets	69	129
Total assets	70,449	30,381
Current liabilities:
Current portion of long-term debt	7,454	5,576
Accounts payable	1,581	629
Accrued expenses	2,574	3,122
Derivative liability related to loan		494
Total current liabilities	11,609	9,821
Long-term debt, net of current portion	5,590	9,293
Total liabilities	17,199	19,114
Commitments and contingencies (Note 2 and 11)
Convertible preferred stock - 0 and 207,164,404 authorized, issued, and outstanding as of June 30, 2020 and December 31, 2019, respectively		129,870
Stockholders' equity (deficit):
Preferred stock, $0.0001 par value: 10,000,000 and 0 shares authorized; no shares issued and outstanding as of June 30, 2020 and December 31, 2019, respectively
Common stock, $0.0001 par value: 300,000,000 shares authorized; 52,151,798 and 9,073,002 shares issued at June 30, 2020 and December 31, 2019, respectively; 50,896,833 and 7,034,047 shares outstanding at June 30, 2020 and December 31, 2019, respectively	5	1
Additional paid-in-capital	187,112	3,304
Accumulated deficit	(133,867)	(121,908)
Total stockholders' equity	53,250	(118,603)
Total liabilities and stockholders' equity	$ 70,449	$ 30,381