NPPA and invasive breast carcinoma: Up-regulation of KP metabolism in BrCa patients was first reported by Rose et al (1967) who found increased kynureninase (KYNU), kynurenine-3-monooxygenase (KMO), and kynurenine aminotransferase-II enzyme activity (Figure 2) in the urine of untreated BrCa patients compared to controls [110].