Identification of Tryptophan-derived biomarkers in brain cancer patients and the effect of tryptophan pathway modulators on brain tumor growth. This project will 1. Measure the whole Kynurenine Pathway (KP) metabolic repertoire in brain cancer patients to identify biomarkers for diagnosis and prognosis and treatment responses, to greatly enhance patient care. 2. Aim to identify new KP modulators that can negatively effect cancer growth.