Effect of spatial transcriptomic-derived intrinsic epithelial signatures on immune cell recruitment and behaviour in the microenvironment of colorectal cancer.

Abstract

251 Background: Colorectal Cancer (CRC) remains a significant healthcare problem. Interest in the role of the Tumour Microenvironment (TME) in progression and metastasis is established, yet much remains to be learned about the mechanism of immune cell recruitment to the TME of primary and metastatic tumours. The Klintrup Makinen (KM) score measures the density of immune infiltrate to the invasive edge of tumours and is associated with good prognosis in primary CRC. Neutrophil infiltration to metastases is a poor prognostic feature suggesting phenotypic differences in the TME at primary and metastatic sites. We set out to examine epithelial determination of the TME in primary CRC. Methods: 180 patient’s primary CRC from a curated TMA underwent deep phenotyping using a multiplex-immunofluorescent panel (DAPI, Panck, CD3 (T cells), FOXP3 (T regulatory cells), CD68 (Macrophages), CD163 (Tumour associated macrophage), CD66b (Neutrophils), KI67). The Nanostring GeoMx Spatial Transcriptomic platform was used to obtain segmented (Tumour: Panck+; TME: Panck-) whole transcriptomic (18000 genes) readout from 54 matched cores from the same TMA. Results: No significant association was demonstrated between immune cell density of any cell types and clinicopathological variables including tumour side, MMR status, N-stage or survival. High KM grade was associated with high CD3 (P = 0.01) and FOXP3 (P = 0.002). Density of all immune cell types were highly corelated. Spatial transcriptomic analysis of the segmented epithelium of patients with high KM grade demonstrated over-expression of known neutrophil chemo-attractant CXCL5 (log2FC 3.76 Adj.P < 0.005). The TME compartments of cores with high CD68 and low CD163 counts were associated with adaptive immune co-ordination with high expression of CXCL13 (log2FC -2.97, Adj.P < 0.005) and CD74 (log2FC -1.42 Adj.P 0.007). IGF2 (log2FC 6.08 Adj.P < 0.005) and LCN15 (log2FC 4.96 Adj.P < 0.005) were globally over-expressed in both TME and epithelium of cores with generalised low immune infiltration. The epithelial compartment neutrophil dense cores also over-expressed IGF2 (log2FC -3.53 Adj.P 0.02). Conclusions: TMAs provide a unique opportunity for broad transcriptomic phenotyping of large numbers of patients simultaneously. The Nanostring GeoMx platform is a flexible tool which can be used in novel ways with other proteomic technologies to drive deeper analysis of the TME. CXCL5 expression in the epithelial compartment drives global immune infiltration to the TME and may be manipulated in different contexts therapeutically through CXCR2 signalling in future.