LICENSE AGREEMENTS AND COMMITMENTS - Lease costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases
Total operating lease costs	$ 174	$ 141
Cash paid for amounts included in the measurement of lease liabilities	188	32
Research and development expense
Leases
Total operating lease costs	123	97
General and administrative expense
Leases
Total operating lease costs	$ 51	$ 44