STOCK-BASED COMPENSATION - Share-based compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Stock options
Stock-based compensation (in dollars)	$ 38	$ 37	$ 138	$ 110
Expected term			10 years
Vesting period			48 months
Cumulative Adjustment on adoption of ASU 2016-09.	8,918	10,096	$ 8,918	10,096	$ 11,577	$ 13,476	$ 15,746	$ 12,814	$ 15,516	$ 18,115
Research and development
Stock options
Stock-based compensation (in dollars)		1	1	(9)
General and administrative
Stock options
Stock-based compensation (in dollars)	38	36	137	119
Stock Options
Stock options
Stock-based compensation (in dollars)	$ 38	$ 31	$ 138	$ 108