SHARE-BASED COMPENSATION - Restricted Stock Unit Activity (Details) - RSUs - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-Based Compensation Awards
Stock-based compensation expenses	$ 49	$ 20	$ 72	$ 36
Restricted stock units issued and outstanding
Outstanding and expected to vest at beginning of period (in shares)			10,296
Granted (in shares)			18,465
Vested (in shares)			(3,429)
Forfeited (in shares)			(247)
Outstanding and expected to vest at end of period (in shares)	25,085		25,085
Weighted average fair value of units granted in period (in dollars per share)			$ 21.19
Unrecognized compensation	$ 462	203	$ 462	$ 203
Expected vesting period			2 years 3 months 21 days	2 years 6 months 18 days
Research and development expense
Share-Based Compensation Awards
Stock-based compensation expenses	44	18	$ 65	$ 32
General and administrative expense
Share-Based Compensation Awards
Stock-based compensation expenses	$ 5	$ 2	$ 7	$ 4

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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