Enrichment of the tumour immune microenvironment in patients with desmoplastic colorectal liver metastasis

Background Patients with resected colorectal liver metastasis (CRLM) who display only the desmoplastic histopathological growth pattern (dHGP) exhibit superior survival compared to patients with any non-desmoplastic growth (non-dHGP). The aim of this study was to compare the tumour microenvironment between dHGP and non-dHGP. Methods The tumour microenvironment was investigated in three cohorts of chemo-naive patients surgically treated for CRLM. In cohort A semi-quantitative immunohistochemistry was performed, in cohort B intratumoural and peritumoural T cells were counted using immunohistochemistry and digital image analysis, and in cohort C the relative proportions of individual T cell subsets were determined by flow cytometry. Results One hundred and seventeen, 34, and 79 patients were included in cohorts A, B, and C, with dHGP being observed in 27%, 29%, and 15% of patients, respectively. Cohorts A and B independently demonstrated peritumoural and intratumoural enrichment of cytotoxic CD8+ T cells in dHGP, as well as a higher CD8+/CD4+ ratio (cohort A). Flow cytometric analysis of fresh tumour tissues in cohort C confirmed these results; dHGP was associated with higher CD8+ and lower CD4+ T cell subsets, resulting in a higher CD8+/CD4+ ratio. Conclusion The tumour microenvironment of patients with dHGP is characterised by an increased and distinctly cytotoxic immune infiltrate, providing a potential explanation for their superior survival

Inflammation and uPAR-Expression in Colorectal Liver Metastases in Relation to Growth Pattern and Neo-adjuvant Therapy

Proteolytic activity and inflammation in the tumour microenvironment affects cancer progression. In colorectal cancer (CRC) liver metastases it has been observed that three different immune profiles are present, as well as proteolytic activity, determined by the expression of urokinase-type plasminogen activator (uPAR).The main objectives of this study were to investigate uPAR expression and the density of macrophages (CD68) and T cells (CD3) as markers of inflammation in resected CRC liver metastases, where patients were neo-adjuvantly treated with chemotherapy with or without the angiogenesis inhibitor bevacizumab. Chemonaive patients served as a control group. The markers were correlated to growth patterns (GP) of liver metastases, i.e. desmoplastic, pushing and replacement GP. It was hypothesised that differences in proteolysis and inflammation could reflect tumour specific growth and therapy related changes in the tumour microenvironment. In chemonaive patients, a significantly higher level of uPAR was observed in desmoplastic liver metastases in comparison to pushing GP (p = 0.01) or replacement GP (p = 0.03). A significantly higher density of CD68 was observed in liver metastases with replacement GP in comparison to those with pushing GP (p = 0.01). In liver metastases from chemo treated patients, CD68 density was significantly higher in desmoplastic GP in comparison to pushing GP (p = 0.03). In chemo and bevacizumab treated patients only a significant lower CD3 expression was observed in liver metastases with a mixed GP than in those with desmoplastic (p = 0.01) or pushing GP (p = 0.05). Expression of uPAR and the density of macrophages at the tumour margin of liver metastasis differ between GP in the untreated patients. A higher density of T cells was observed in the bevacizumab treated patients, when desmoplastic and pushing metastases were compared to liver metastases with a mix of the GP respectively, however no specific correlations between the immune markers of macrophages and T cells or GP of liver metastases could be demonstrated.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Estructuras Microscópicas (CIEMIC