Stock-Based Compensation (Tables)

6 Months Ended

12 Months Ended

Jun. 30, 2020

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Summary of Outstanding Warrants

A summary of the outstanding warrants at both December 31, 2019 and March 31, 2020 is as follows:

Date Granted	Number		Exercise Price		Expiration Date
6/17/2015		5,267,959	$	2.8474		7/17/2022
12/7/2015		5,267,959	$	2.8474		7/17/2022
9/7/2016		5,268,035	$	2.8474		7/17/2022
7/11/2017		5,268,034	$	2.8474		7/17/2022

Schedule of Unvested Profits Interest Unit Activity

Unvested profits interests unit’s activity for the year ended December 31, 2019 and 2018, was as follows:

	Number of Nonvested Profits Interests			Weighted Average Grant Date Fair Value
Outstanding at January 1, 2018		9,765,439			0.08
Granted		16,143,382			0.22
Vested		(4,790,327	)		0.07
Forfeited		(1,186,217	)		0.12
Outstanding at December 31, 2018		19,932,277			0.19
Granted		19,643,100			0.16
Vested		(7,044,620	)		0.14
Forfeited		(10,588,658	)		0.21
Outstanding at December 31, 2019		21,942,099			0.18
Expected to vest at December 31, 2018		19,932,277
Expected to vest at December 31, 2019		21,942,099

Schedule of Value Profits Interests Granted

The assumptions used to value profits interests granted during the six months ended June 30, 2020 and 2019 are as follows:

	June 30, 2020			June 30, 2019
Expected term (in years)		6.0			6.0
Risk-free rate		0.36	%		2.43	%
Expected volatility		140.45	%		72.02	%
Expected dividend yield		0	%		0	%

The assumptions used to value profits interests granted during the years ended December 31, 2019 and 2018 were as follows:

	2019			2018
Expected term (in years)		6.0			6.0
Risk-free rate		1.74	%		2.51	%
Expected volatility		72.75	%		60.28	%
Expected dividend yield		0.00	%		0.00	%

Schedule of Unvested Restricted Stock Activity

A summary of the Company’s unvested restricted stock activity and related information during the six months ended June 30, 2020 is as follows:

Weighted Average Grant Date Fair Value
Nonvested, January 1, 2020	2,038,955		2.04
Granted	879		2.34
Vested	(150,379	)	0.57
Forfeited or canceled	(634,491	)	1.83
Nonvested, June 30, 2020	1,254,965		2.33

Schedule of Stock-Based Compensation Activity

The Company has recognized the following compensation cost related to employee and non-employee stock-based compensation activities (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Research and development	$	31	$	61	$	112	$	175
General and administrative		152		124		318		265
Total	$	183	$	185	$	430	$	440