STOCK BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2019

Stock-based compensation

Schedule of stock-based compensation expenses

Total stock‑based compensation expense recorded for employees, directors and non‑employees (in thousands):

	Year Ended
	December 31,
	2019		2018
Research and development	$	2,762	$	140
General and administrative		3,409		132
Total stock-based compensation expense	$	6,171	$	272

Schedule of options outstanding

The following table summarizes the information about options outstanding at December 31, 2019 (in thousands, except share and per share data):

				Weighted-Average
		Weighted-		Remaining	Aggregate
	Options	Average		Contractual	Intrinsic
	Outstanding	Exercise Price		Term (in years)	Value
Outstanding at December 31, 2018	1,202,979	$	1.35	9.14	$	4,026
Options granted	2,969,945		6.57
Options exercised	(81,988)		2.77			—
Forfeited	(11,048)		4.70
Expired	—		—
Outstanding at December 31, 2019	4,079,888	$	5.11	8.26	$	82,327
Exercisable at December 31, 2019	1,447,191	$	2.78	8.45	$	34,818
Nonvested at December 31, 2019	2,632,697	$	6.39	8.15	$	47,508

Stock options - Service conditions only

Stock-based compensation

Schedule of valuation assumptions

	Year Ended
	December 31,
	2019			2018
Expected term (in years)		5.7			5.9
Volatility		72.54	%		71.78	%
Risk-free interest rate		2.17	%		2.71	%
Dividend yield		0.00	%		0.00	%

Stock options - Service, performance and market conditions

Stock-based compensation

Schedule of valuation assumptions

	Year Ended
	December 31,
	2019
Time to expiration (in years)		10.0
Volatility		68.54	%
Risk-free interest rate		2.64	%
Dividend yield		0.00	%
Cost of equity		24.00	%
Fair value of underlying common stock (as of valuation date)	$	5.85