COMMITMENTS AND CONTINGENCIES - Narrative (Details)		1 Months Ended					3 Months Ended			9 Months Ended		12 Months Ended
	May 11, 2023 USD ($) shares	Jan. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jul. 31, 2022 USD ($)	May 31, 2022 USD ($)	Dec. 31, 2021 USD ($) shares	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) renewal_term	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Jul. 24, 2023 shares	Mar. 31, 2021 USD ($)	Oct. 31, 2020 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of renewal terms (up to) | renewal_term										3
Lessee, operating lease, renewal term				3 years			3 years			3 years
Operating lease right-of-use asset			$ 1,610,000				$ 1,855,000			$ 1,855,000					$ 1,600,000	$ 100,000
Lease discount rate															6.00%	6.00%
Lease remaining term															12 months
Operating lease liability, short-term			613,000				821,000			821,000						$ 100,000
Operating lease, annual base rent				$ 400,000
Long term lease obligation							$ 1,200,000			$ 1,200,000
Operating lease, liability, noncurrent, statement of financial position [Extensible List]							Other liabilities			Other liabilities
Amortization expense relating to operating lease right-of-use assets							$ 200,000		$ 100,000	$ 600,000	$ 400,000
Operating lease expenses							100,000		$ 100,000	$ 300,000	$ 200,000
ImmunoGen, Inc
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments																48,000,000
Collaborative arrangement, milestone payment			$ 10,000,000		$ 3,000,000	$ 2,500,000
Potential royalty payments																$ 95,000,000
Xencor, Inc
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments						27,800,000						$ 27,800,000	$ 30,000,000
Potential royalty payments						$ 20,000,000						$ 20,000,000	$ 25,000,000
Shares issued in exchange for rights granted (in shares) | shares						394,737						394,737	322,407
Value of shares issued in exchange for rights granted												$ 7,500,000	$ 6,000,000
Collaboration arrangement, research license and selection rights, term						1 year
Collaboration arrangement, potential development milestone payment, maximum						$ 4,800,000						4,800,000
Collaborative arrangement, potential special payments, maximum						$ 3,000,000						$ 3,000,000
Enable Injections
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments		$ 45,000,000
Potential royalty payments		150,000,000
Collaborative arrangement, rights and licenses fee		$ 15,000,000
Third Party Collaborator
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments	$ 45,000,000
Potential royalty payments	$ 60,000,000
Shares issued in exchange for rights granted (in shares) | shares	204,843
Shares issued exchange for rights for granted (in shares) | shares														39,059
Value of shares issued in exchange for rights granted							$ 700,000	$ 5,000,000
Collaborative arrangement, value of shares to be issued for rights granted	$ 10,000,000