11. Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Summary of RSU activity

The following table summarizes the activity of the Company’s RSUs for the year ended December 31, 2020:

	Number of Shares			Weighted- Average Grant Date Fair Value Per Share
Unvested units at December 31, 2019		14,945		$	20.50
Granted		–			–
Vested		(4,282	)		22.18
Forfeited		(964	)		18.33
Unvested units at December 31, 2020		9,699		$	19.97

Fair value assumptions used

	December 31, 2019
Risk-free interest rate	1.85 – 2.58%
Expected volatility	97.67 – 98.87%
Expected lives (in years)	5.31
Expected dividend yield	0.00%

Summary of Stock Option Activity

The following table summarizes the activity of the Company’s stock option plan for the year ended December 31, 2020:

	Total Number of Shares			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Term		Aggregate Intrinsic Value
Balance at December 31, 2019		2,659		$	3,298.90
Granted		–			–
Exercised		–			–
Cancelled		(89	)		2,671.45
Balance at December 31, 2020		2,570		$	3,334.06		6.22 years	$	–
Exercisable at December 31, 2020		1,855		$	4,578.01		5.70 years	$	–

Details of Stock-based Compensation Expense Recorded

	December 31,
	2020		2019
Research and development	$	22	$	21
General and administrative		114		279
Total stock-based compensation	$	136	$	300