STOCKHOLDERS' EQUITY - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Number of Option Shares
Outstanding at beginning of period (in shares)	4,270,544
Granted (in shares)	987,039
Forfeited (in shares)	(427,421)
Expired (in shares)	(17,801)
Exercised (in shares)	0
Outstanding at ending of period (in shares)	4,812,361	4,270,544
Options exercisable at ending of period (in shares)	1,899,175
Weighted-Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 9.98
Granted (in dollars per share)	1.89
Forfeited (in dollars per share)	9.60
Expired (in dollars per share)	12.54
Exercised (in dollars per share)	0
Outstanding at ending of period (in dollars per share)	8.35	$ 9.98
Options exercisable at ending of period (in dollars per share)	$ 11.08
Weighted-Average Contractual Term (in years) and Aggregate Intrinsic Value (in thousands)
Outstanding, Weighted-Average Contractual Term (in years)	8 years 1 month 6 days	8 years 6 months
Options exercisable, Outstanding, Weighted-Average Contractual Term (in years)	6 years 9 months 18 days
Outstanding, Aggregate Intrinsic Value	$ 0	$ 0
Options exercisable, Aggregate Intrinsic Value	$ 0