IDO1 and neoplasm: To abolish the potential effect of the low and strongly variable IDO1 expression on the reliability of the efficacy model, we developed a syngeneic mouse model using B16F10 melanoma cells stably overexpressing mIDO1. While we have demonstrated strong target modulation in this model upon treatment with NTRC 3883-0, we did not observe an effect of IDO1 expression or IDO1 inhibitor treatment on the tumor growth rate.