Abstract 2811: A translational immuno-oncology platform to model the tumor microenvironment <i>in vitro</i>
Authors: Louise S. Brackenbury, S. Rhiannon Jenkinson, Shilina Roman, Robert D. Nunan, Sylvie D. Hunt, Anna Willox, Neil A. Williams, Omar Aziz, Ian Waddell
Journal: Cancer Research (2019)

Abstract The tumor microenvironment (TME) is a complex network, consisting of the tumor, blood vessels, stromal and immune cells, and soluble factors. The immune system plays an important role in combating tumor growth, and multiple studies associate raised immune infiltrate with beneficial outcome. Various tractable immuno-oncology targets have been identified, both in the TME and immune cells. It is critical to test novel immuno-modulators in assays involving multiple cell types, to understand the MOA and identify biomarkers before moving into the clinic. Charles River have developed a range of primary human assays to model the TME in vitro. This platform models multiple anti-tumor immune effector pathways and has been validated with standard of care therapeutics. The assays include: T cell or NK cell-mediated tumor killing, myeloid/macrophage assays, Th1/Th17/iTreg differentiation and regulatory T cell suppression assays. Tumor killing assays were performed using an IncuCyte ZOOM and PBMC were cultured with tumor monolayers with TCR ligation. Keytruda and Yervoy raised levels of tumor cell death, indicating that they enhanced T cell killing. To further model the TME, 3D ‘spheroids’ were used to screen for either T cell mediated or ADCC-mediated NK cell killing. For ADCC, PBMC were co-cultured with tumor spheroids and killing measured by monitoring spheroid diameter in the presence of Herceptin, which potentiated NK-driven tumour killing. Myeloid/macrophage cells were differentiated from monocytes in tumor-conditioned media (TCM). TCM drove the generation of immature cells which were CD25lo, CD127lo, CD184hi, CD80lo, CD163hi, CD68lo and MHCIIlo. These cells produced IL-10 and VEGF and were suppressive in a T cell assay. Phagocytosis assays were also performed using anti-CD47 as a control. The TME is associated with increased Treg numbers and low levels of Th1 or Th17 cells. Many therapeutics aim to shift the balance away from Treg, towards Th1 or Th17 cells. Assays were therefore performed by differentiating naïve CD4+ T cells into iTreg, in the presence or absence of a USP7 inhibitor. Reduced iTreg generation, without significant alteration in Th1/17 frequency was observed. The resulting iTreg were less able to suppress T cell proliferation when compared to non-treated iTreg. Suppression assays were also performed using nTreg. As before, the USP7 inhibitor partially reversed nTreg-mediated suppression. Charles River is pleased to present an immuno-oncology platform to model the TME in human cells in vitro, enabling partners to rapidly assess the immunomodulatory capacity of their therapeutics. The 3D assays represent an important complex cell model to support translational drug discovery, sitting alongside T cell-mediated tumor killing, myeloid/macrophage assays, Th1/Th17/ iTreg differentiation and nTreg assays and helps to define the diverse aspects of micro-environmental control of immune response. Citation Format: Louise S. Brackenbury, S. Rhiannon Jenkinson, Shilina Roman, Robert D. Nunan, Sylvie D. Hunt, Anna Willox, Neil A. Williams, Omar Aziz, Ian Waddell. A translational immuno-oncology platform to model the tumor microenvironment in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2811.