STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement [Abstract]

Schedule of Stock Option Activity

A summary of stock option activity under the 2009 Plan and the Vical Plan is as follows, as converted associated with stock split and conversion:

	Shares		Weighted Average Exercise  Price		Total Intrinsic Value		Weighted Average Remaining Contractual Life  (In Years)
Outstanding at December 31, 2018	696,842		$	13.21
Acquired under Vical Plan	184,087		$	75.98
Granted	1,088,260		$	4.67
Exercised	—		$	—
Forfeited or expired	(175,587	)	$	28.22
Outstanding at December 31, 2019	1,793,602		$	13.00	$	4,971	8.49
Options vested and exercisable at December 31, 2019	525,665		$	28.41	$	73,878	5.97

Schedule of Share-Based Compensation Expense

Share-based Compensation Expense

Total stock-based compensation expense related to stock options granted under the 2009 Plan and the Vical Plan was allocated as follows (in thousands):

	Year Ended December 31,
	2019		2018
Research and development	$	349	$	340
General and administrative	1,183		371
Total stock-based compensation expense	$	1,532	$	711

Schedule of Valuation Assumptions

The assumptions used to calculate the fair value of stock options granted to non-employees under the 2009 Plan are as follows, presented on a weighted average basis:

	Year Ended December 31,
	2019		2018
Expected term (in years)	6.02		9.96
Expected volatility	82.82	%	86.17	%
Risk free interest rate	1.49	%	2.69	%
Expected dividend yield	—	%	—	%

The assumptions used to calculate the fair value of stock options granted to employees and non-employee directors under the 2009 Plan are as follows, presented on a weighted average basis:

	Year Ended December 31,
	2019		2018
Expected term (in years)	6.1		6.1
Expected volatility	83.22	%	85.43	%
Risk free interest rate	1.44	%	2.77	%
Expected dividend yield	—	%	—	%