Purpose Indoleamine 2,3 dioxygenase 1 (IDO1) mediates potent immunosuppression in multiple preclinical models of cancer. However, the basis for elevated IDO1 expression in human cancer, including the most common primary malignant brain tumor in adults, glioblastoma (GBM), is poorly understood. The major objective of this study is to address this gap in our understanding of how IDO1 expression contributes to the biology of GBM, and whether its level of expression is a determinant of GBM patient outcome. Experimental Design Patient-resected GBM, the cancer genome atlas, human T cell:GBM co-cultures, as well as nu/nu, NOD-scid and humanized (NSG-SGM3-BLT) mice engrafted human GBM, form the basis of our investigation. Results In situ hybridization for IDO1 revealed transcript expression throughout patient-resected GBM, whereas immunohistochemical IDO1 positivity was highly variable. Multivariate statistical analysis revealed that higher levels of IDO1 transcript predict a poor patient prognosis (P=0.0076). GBM IDO1 mRNA levels positively correlated with increased gene expression for markers of cytolytic and regulatory T cells, in addition to decreased patient survival. Humanized mice intracranially-engrafted human GBM revealed an IFNγ-associated T cell-mediated increase of intratumoral IDO1. Conclusions Our data demonstrate that high intratumoral IDO1 mRNA levels correlate with a poor GBM patient prognosis. It also confirms the positive correlation between increased GBM IDO1 levels and human-infiltrating T cells. Collectively, this study suggests that future efforts aimed at increasing T cell-mediated effects against GBM, should consider combinatorial approaches that co-inhibit potential T cell-mediated IDO1 enhancement during therapy.

Elevated glycolysis is a common metabolic trait of cancer, but what drives such metabolic reprogramming remains incompletely clear. We report here a novel transcriptional repressor-mediated negative regulation of glycolysis. ZBTB7A, a member of the POK (POZ/BTB and Kr€ uppel) transcription repressor family, directly binds to the promoter and represses the transcription of critical glycolytic genes, including GLUT3, PFKP, and PKM. Analysis of The Cancer Genome Atlas (TCGA) data sets reveals that the ZBTB7A locus is frequently deleted in many human tumors. Significantly, reduced ZBTB7A expression correlates with up-regulation of the glycolytic genes and poor survival in colon cancer patients. Remarkably, while ZBTB7A-deficient tumors progress exceedingly fast, they exhibit an unusually heightened sensitivity to glycolysis inhibition. Our study uncovers a novel tumor suppressor role of ZBTB7A in directly suppressing glycolysis.

Introduction, Materials and Methods, Results, and Discussion): 6,973Conflict of Interests Disclosure: RDU and SJC are inventors named in patent applications that describe the use of complement inhibitors for therapeutic purposes and the use of circulating complement protein measurement for patient stratification. They are also co-founders of and shareholders in Complement Research.