LICENSE AGREEMENTS AND COMMITMENTS - Lease costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases
Total operating lease costs	$ 173	$ 187	$ 347	$ 328
Cash paid for amounts included in the measurement of lease liabilities	205		393
Research and development expense
Leases
Total operating lease costs	124	141	247	238
General and administrative expense
Leases
Total operating lease costs	$ 49	$ 46	$ 100	$ 90