NU223612 is a potent PROTAC ( PROTACs ) that degrades indoleamine 2,3-dioxygenase 1 ( IDO1 ) ( Indoleamine 2,3-Dioxygenase ( IDO ) ) with a K d of 640 nM. NU223612 potently degrades the IDO1 protein through CRBN -mediated proteasomal degradation. NU223612 is bound to CRBN with an affinity of 290 nM. NU223612 can cross the blood-brain barrier (BBB).