Author of

• 17398

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  P2.01 - Poster Session with Presenters Present (ID 461)

  • Event: WCLC 2016
  • Type: Poster Presenters Present
  • Track: Biology/Pathology
  • Presentations: 1
  • Moderators:
  • Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)

  • 17463

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    P2.01-065 - Quantification of Tumour-Immune Cell Spatial Relationships in the Lung Tumour Microenvironment Using Single Cell Profiling (ID 6104)

    14:30 - 14:30  |  Author(s): P. Gallagher
    • Abstract

    Background:
    How clinical-genomic features of the lung tumour microenvironment (TME) influence immune-checkpoint-blockade therapy is not well understood. Immunohistochemistry (IHC) is necessary to decipher cell-cell relationships that cannot be observed by bulk tumour profiling. In this pilot study, we assess whether immune cell phenotypes and spatial relationships differ between lung adenocarcinoma (LUAD) from smokers/non-smokers, KRAS/EGFR mutation, or with stage and tumour size using a novel multicolour IHC quantitative pathology method that enables in situ single cell profiling within the TME.
    
    Methods:
    Two consecutive sections from 21 cases of LUAD were stained with multicolour IHC panels to assess immune cell composition (CD8, CD3, CD79a) and T-cell exhaustion (CD8, PD1, PDL1). Hyperspectral images were captured as directed by a pathologist and analyzed using software developed in-house. The software segments individual cell boundaries based on haematoxylin stain. IHC stain positivity thresholds were applied based on intensity. Tumour and immune cells were classified into groups based on IHC staining. Interactions between specific groups were quantified by assessing the frequency and variance of the spatial relationship of each group vs. all other groups. Voronoi tessellation, based on cell centres, was used to define “next to”. Group counts and relationships were then compared with clinical features using a Student’s t-test or Kruskal-Wallis test.
    
    Results:
    A greater number of cells expressed PDL1 in KRAS+ LUAD. While the total number of CD8+PD1+ T-cells did not differ between KRAS+ and EGFR+ LUAD, there was an observed increased proximity between PDL1+ cells and CD8+PD1+ T-cells in KRAS+ LUAD. In EGFR+ LUAD, CD8+ T-cells that did not express PD1 were primarily localized in PDL1 negative regions. Both EGFR+ LUAD and never smokers harbored a higher proportion of CD8- T-cells and CD3-CD8+ immune cells. Both immune cell types were frequently localized in clusters with CD8+ T-cells. KRAS+ LUAD and smokers had increased B-cell counts. No significant associations of PD1 and PDL1 expression were found with stage; however, there was a statistically significant increase in proximity between varied immune cell types as stage and tumour size increased.
    
    Conclusion:
    Our method enabled identification of specific cell-cell spatial relationships within LUAD that are associated with smoking history and KRAS/EGFR mutation. Despite limited sample size, we observed an increased proximity between PDL1+ cells and CD8+PD1+ T-cells in KRAS+ LUAD. TME single cell profiling and cell sociology is a promising method to improve stratification of patients for immune-checkpoint-blockade therapies and opens new avenues to explore the complex cell-cell interactions within the TME.