WARRANTS (Tables)

3 Months Ended

Mar. 31, 2021

Warrant [Abstract]

Summary of Assumptions using Black- Scholes Option Pricing Model to estimate fair value

The aggregate fair value of the 2018 Offering Warrants of $7.4 million was estimated using the Black-Scholes option-pricing model with the following assumptions:

	Upon Issuance
Common Stock Warrants:
Expected term (in years)		7.0
Expected volatility (%)	62.5%
Risk-free interest rate (%)	2.8%
Expected dividend yield (%)	0%

The fair value of the 2017 and 2016 Placement Warrants at March 31, 2021 and December 31, 2020, respectively, was estimated using the Black-Scholes option-pricing model and the following weighted-average assumptions:

	2017 Placement Warrants						2016 Placement Warrants
	March 31, 2021			December 31, 2020			March 31, 2021			December 31, 2020
Expected term (in years)		2.8			3.0			2.4			2.6
Expected volatility		90.3	%		86.9	%		89.4	%		86.3	%
Risk-free interest rate		0.3	%		0.2	%		0.2	%		0.2	%
Expected dividend yield		0.0	%		0.0	%		0.0	%		0.0	%

Schedule of Key Terms of Placement Warrants

The key terms of the 2017 and 2016 Placement Warrants are as follows:

	Issuance Date	Term	Exercise Price Per Share		Warrants Exercised during the three months ended March 31, 2021		Warrants Outstanding at March 31, 2021
2017 Placement Warrants	January 2017	7 years	$	3.17		112,609		1,506,281
2016 Placement Warrants	August and September 2016	7 years	$	2.95		552		536,711
Total						113,161		2,042,992