The PD-L 1-and IL 6-mediated dampening of the IL 27 / STAT 1 anticancer responses are prevented by α-PD-L 1 or α-IL 6 antibodies

1University of Luxembourg, Life Sciences ResearchUnit—Signal Transduction Laboratory, Belvaux, Luxembourg 2University of Luxembourg, Life Sciences ResearchUnit—Bioinformatics Core Facility, Belvaux, Luxembourg 3UniversityHospitalWürzburg,Medical Clinic II, Division ofHepatology,Würzburg, Germany 4Proteome andGenomeResearchUnit, Department ofOncology, Luxembourg Institute of Health, Luxembourg, Luxembourg 5University of Luxembourg, Life Sciences ResearchUnit—MolecularDiseaseMechanisms Laboratory, Belvaux, Luxembourg Correspondence ClaudeHaan,University of Luxembourg, Life SciencesResearchUnit—Signal Transduction Laboratory, 6, avenueduSwing, L-4367Belvaux, Luxembourg. E-mail: claude.haan@uni.lu Abstract Interleukin-27 (IL27) is a type-I cytokine of the IL6/IL12 family and is predominantly secreted by activated macrophages and dendritic cells. We show that IL27 induces STAT factor phosphorylation in cancerous cell lines of different tissue origin. IL27 leads to STAT1 phosphorylation and recapitulates an IFN-γ-like response in the microarray analyses, with up-regulation of genes involved in antiviral defense, antigen presentation, and immune suppression. Like IFN-γ , IL27 leads to an up-regulation of TAP2 and MHC-I proteins, which mediate increased tumor immune clearance. However, both cytokines also upregulate proteins such as PD-L1 (CD274) and IDO-1, which are associatedwith immune escape of cancer. Interestingly, differential expression of these geneswas observedwithin the different cell lines andwhen comparing IL27 to IFN-γ . In coculture experiments of hepatocellular carcinoma (HCC) cells with peripheral blood mononuclear cells, pre-treatment of the HCC cells with IL27 resulted in lowered IL2 production by anti-CD3/-CD28 activated T-lymphocytes. Addition of anti-PD-L1 antibody, however, restored IL2 secretion. The levels of other TH1 cytokines were also enhanced or restored upon administration of anti-PD-L1. In addition, we show that the suppression of IL27 signaling by IL6-type cytokine prestimulation—mimicking a situation occurring, for example, in IL6-secreting tumors or in tumor inflammation–induced cachexia—can be antagonized by antibodies against IL6-type cytokines or their receptors. Therapeutically, the antitumor effects of IL27 (mediated, e.g., by increased antigen presentation)might thus be increased by combining IL27with blocking antibodies against PD-L1 or/and IL6-type cytokines.