Curcumin and Gemcitabine were selected based on the following criteria: (I) interference with IDO; (II) direct cytotoxic activity against tumor cells (via induction of immunogenic cell death) in (pre-)clinical studies, (III) safe application with minimal toxic side effects (at least in low-doses) in patients, and (IV) enhanced antitumoral effects when given in conjunction with other drugs. Here, IDO1 is linked to neoplasm.