Cabalag CS (1), PRALL O(1), CICIULLA J(2), THIO N(1), NEESON PJ(1), MIR ARNAU G(1), PHILLIPS WA^(1), CLEMONS NJ^(1), DUONG CP^(1)
Tumour-infiltrating lymphocytes (TILs) have been shown to be prognostic in a number of solid organ tumours1. The aim of this study was to determine whether TILs and expression of immune-cell related genes are associated with treatment response and prognosis in oesophageal cancer (OC).
Study cohort consisted of 58 patients who had neoadjuvant chemoradiotherapy (CRT) followed by surgical resection. TILs were quantified in separate compartments (tumour/stroma/scar) where the final percentage score was determined by the area of infiltration by TILs and the denominator is the percentage area occupied by the compartment of interest. RNA was extracted from sections where TILs were quantified and gene expression was assessed using the Nanostring Platform based on the PanCancer Immune Profiling Panel.
For patients who had low pre-treatment TIL counts, an increase in TIL count after CRT was associated with a superior progression free survival (p < 0.01). In complete and partial responders, high TIL infiltration (>10% of tumour/scar area) in resection specimens was independently associated with improved disease specific survival (HR 0.3; 95%CI 0.09 – 0.94; p < 0.05) in multivariate analysis. The presence of tertiary lymphoid structures in post-treatment samples was associated with less disease recurrence (p = 0.01). Genes associated with the presence of immunosuppressive M2 macrophages and neutrophils were highly expressed in post-treatment specimens.
Assessment of TIL infiltration and immune microenvironment in pre-treatment and post-treatment OC specimens may provide additional prognostic information. Treatment resistance in OC maybe explained by the possible presence of immunosuppressive cells in the tumour immune microenvironment.