COMMITMENTS AND CONTINGENCIES (Details) - Licensing Agreements $ in Thousands			3 Months Ended		12 Months Ended
	Dec. 10, 2015 USD ($)	Jun. 10, 2015 USD ($) product	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2019 USD ($)
Baylor
Long-term Purchase Commitment [Line Items]
Sublicense expense			$ 500	$ 600	$ 600
Agensys
Long-term Purchase Commitment [Line Items]
Nonrefundable upfront fee	$ 3,000
Milestone payments upon first achievement of specified clinical milestones	5,000
Milestone payments upon achievement of specified clinical milestones for each licensed product	50,000
Milestone payments upon achievement of sales milestones	75,000
Option exercise fee	5,000
Milestone payments reduced upon exercise of option	$ 65,000
Termination period, number of years after first commercial sale of licensed product	10 years
Termination period, notice of failure on uncured items	60 days
Period of notice of failure on uncured items, if material breach is related to failure to make payments	30 days
BioVec
Long-term Purchase Commitment [Line Items]
Nonrefundable upfront fee		$ 100
Milestone payments upon first achievement of specified clinical milestones		$ 250
Termination period, notice of failure on uncured items		60 days
Upfront fee payment period, number of days from effective date		10 days
License costs due upon first release of product		$ 300
License costs due upon first release of product, period of payment		10 days
License agreement, annual fee		$ 150
License agreement, annual fee period, from first IND filing		30 days
Milestone payments, number of initial products | product		3
License agreement, milestone payments upon receipt of FDA or EMA registration		$ 2,000
Termination notice period for any other breach		90 days
Termination period, after insolvency event		30 days