University of Pittsburgh Medical Center Pittsburgh, PA
D. F. Hamade1, M. Epperly1, R. Fisher2, W. Hou2, D. Shields2, J. P. van Pijkeren3, B. Leibowitz4, L. Coffman5, H. Wang6, M. S. S. Huq7, C. J. Rogers8, J. S. Greenberger1, and A. Mukherjee9; 1UPMC-Shadyside Hospital Department of Radiation Oncology, Pittsburgh, PA, 2University of Pittsburgh, Pittsburgh, PA, 3The University of Wisconsin Madison, Madison, WI, 4Department of Radiation Oncology, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, 5Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, 6Department of Biostatistics, School of Public Health, University of Pittsburgh, Pittsburgh, PA, 7Department of Radiation Oncology, UPMC Hillman Cancer Center, Pittsburgh, PA, 8Chromologic LLC, Pasadena, CA, 9University Of Pittsburgh, Pittsburgh, PA
Purpose/Objective(s): Establish a novel therapeutic strategy for the management of ovarian cancer with LR-IL-22 gavage, an intestinal radioprotector, through its pivotal role in modifying the tumor microenvironment and subsequently improving the survival of female C57BL/6MUC-1 mice with widespread abdominal syngeneic 2F8cis ovarian cancer. Materials/
Methods: To assess differential gene expression following irradiation and LR-IL-22 gavage, we performed RNAseq analyses using Lgr5+GFP+ mice. Male and female mice were divided into four groups: control (0 Gy), 12 Gy total body irradiation (TBI), 12 Gy TBI + LR, and 12 Gy TBI + LR-IL-22. Twenty-four hours after TBI, mice received LR or LR-IL-22 gavage. In a separate experiment with female C57BL/6MUC-1 mice with widespread abdominal syngeneic 2F8cis ovarian cancer, flow analysis and immunohistochemistry were used to assess the tumor microenvironment following fractionated whole abdomen irradiation (WAI) using 6 Gy × 4 fractions with or without LR-IL-22 gavage. Results: We observed that intestinal stem cell gene expression varied widely following exposure to TBI. Genes were either upregulated or downregulated following irradiation, and many were solely rescued by the genetically engineered probiotic LR-IL-22. In fact, 135 genes were uniquely rescued and thus downregulated by LR-IL-22, compared to 43 genes uniquely rescued and thus upregulated by LR-IL-22 following TBI. Moreover, the addition of fractionated WAI to LR-IL-22 not only induced PD-L1 protein expression in ovarian cancer cells and mobilized CD8+ T cells, but potentially reduced tumor growth rate through the migration of LR bacteria into the 2F8cis ovarian tumors. Conclusion: Our data illustrates the effectiveness of LR-IL-22 as a radiation mitigator that manifests its role by modifying both, gene expression and the tumor microenvironment, following irradiation. Indeed, irradiation induced differential gene expression in intestinal stem cells, and significantly upregulated CD8+ T cells infiltrates in 2F8cis tumors, giving them an immunological ‘‘hot’’ phenotype which positively correlated with PD-L1 expression. This forms the basis for combining WAI with targeted therapies, including immune checkpoint inhibitors, in advanced or recurrent epithelial ovarian cancer.
