The present invention relates to a method of predicting the therapeutic efficacy of at least one therapy approach in the treatment of a neoplastic disease in a patient. The method comprises the following steps: a) Determining the presence or concentration of at least one enzyme or metabolite of the Kynurenine pathway in a patient sample, and b) Concluding, from step a), whether the at least one therapy approach will be therapeutically effective in the treatment of the neoplastic disease.