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DEBT - Additional Information (Details) - Hercules and Silicon Valley Bank [Member] - USD ($)		9 Months Ended
	Aug. 12, 2021	Sep. 30, 2020	Sep. 30, 2021	Jun. 15, 2021
Debt Instrument [Line Items]
Maximum borrowing capacity under term loan		$ 75,000,000
Minimum
Debt Instrument [Line Items]
Debt covenant minimum cash balance		25,000,000
Debt covenant max cash upon licensing transaction		30,000,000
Maximum
Debt Instrument [Line Items]
Debt covenant minimum cash balance	$ 30,000,000
Debt covenant max cash upon licensing transaction	$ 35,000,000
Tranche A [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity under term loan		35,000,000
Principal amount outstanding under term loan		25,000,000	$ 35,000,000
Remaining amount drawn down under Tranche A term loan				$ 10,000,000
Carrying value of term loan, net			34,669,000
Unamortized debt discount and issuance costs			836,000
Accrued end of term charge			$ 505,000
Tranche B [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity under term loan		$ 15,000,000
Start date to borrow under a tranche for a debt instrument		Jan. 01, 2021
Expiration date to borrow under a tranche for a debt instrument		Dec. 15, 2021
Tranche C [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity under term loan		$ 25,000,000
Expiration date to borrow under a tranche for a debt instrument		Dec. 31, 2022

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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