Inhibitors of thisenzyme act by preventing tryptophan metabolism.95 However, these drugs have not succeeded in enhancing thesurvival rate of cancer patients,96 soa new emerging approach to degrade IDO1 is PROTAC.97 PROTAC targeting IDOC degrades this protein by proteasomeIDO1 converts tryptophan to kynurenines many inhibitor drugs wereused against IDO1 but failed to inhibit its nonenzymatic immunosuppressivefunctions. Here, IDO1 is linked to cancer.