Consistent with our prior findings in lung adenocarcinoma [3], the mRNA levels of KYNU, as well as several of the KP enzymes upstream of KYNU, were statistically significantly elevated (Wilcoxon rank sum test 2-sided p < 0.0001) in PDAC tumors compared to adjacent control tissues, whereas those of 3-hydroxyanthranilate 3,4-dioxygenase (HAAO), and quinolinate phosphoribosyltransferase (QPRT), enzymes involved in de novo NAD+ biosynthesis, were reduced (Figure 2A). This evidence concerns the gene HAAO and lung adenocarcinoma.