Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2021

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule of Summarizes Stock Option Activities

The following table summarizes stock option activities for the six months ended June 30, 2021:

				Weighted Average
				Remaining
		Weighted Average		Contractual Life (in
	Stock Options	Exercise Price		years)
Outstanding at December 31, 2020	1,141,675		5.73	6.31
Outstanding at June 30, 2021	1,141,675		5.73	5.81
Options vested and exercisable at June 30, 2021	856,257	$	5.73	5.81

Schedule of Stock-Based Compensation Expense

The following table summarizes stock-based compensation expense for the three and six months ended June 30, 2021 and 2020 (in thousands):

	For the three months ended June 30,				For the six months ended June 30,
	2021		2020		2021		2020
General and administrative	$	240	$	513	$	564	$	865
Research and development		307		444		979		897
Total stock-based compensation expense	$	547	$	957	$	1,543	$	1,762

Summary of Warrant Activities

A summary of warrant activities for the six months ended June 30, 2021 is presented below:

				Weighted Average
				Remaining
		Weighted Average		Contractual Life (in
	Warrants	Exercise Price		years)
Outstanding as of December 31, 2020	5,402,670	$	8.21	1.39
Cashless exercised	(138)		—	—
Outstanding as of June 30, 2021	5,402,532	$	8.21	0.89

Restricted Stock Awards [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedules of Restricted Stock and Restricted Stock Unit Activity

The following table summarizes restricted stock award activities for the six months ended June 30, 2021:

		Weighted Average
		Grant Date Fair
	Number of Shares	Value
Nonvested at December 31, 2020	302,114	$	4.93
Granted	68,870		3.63
Vested	(90,001)		6.69
Nonvested at June 30, 2021	280,983	$	4.05

Restricted Stock Units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedules of Restricted Stock and Restricted Stock Unit Activity

Certain employees and consultants have been awarded restricted stock units with time-based vesting. The following table summarizes restricted stock units’ activities for the six months ended June 30, 2021:

		Weighted Average
		Grant Date Fair
	Number of Units	Value
Nonvested at December 31, 2020	1,468,559	$	3.87
Granted	1,100,000		3.45
Forfeited	(242,062)		3.74
Vested	(246,188)		4.49
Nonvested at June 30, 2021	2,080,309	$	3.59