PURPOSE: Primary cilium (PC) is considered to be a functional homologue of the immune synapse. Microtubule structures, PC of cancer associated fibroblasts and immune synapses between cytotoxic CD8+ tumor infiltrating lymphocytes (TILs) and cancer cells, are regularly found in varying amounts in the microenvironment of solid tumors. The purpose of this study was to find out the potential association and combined prognostic significance of the frequency of PC, PD-1 and CD8+ TILs in patients with intestinal cancer. METHODS: The frequency of PC, programmed cell death protein-1 receptor (PD-1) expression and the frequency of stromal and intraepithelial CD8+TILs were evaluated in samples of colorectal adenocarcinoma (32 patiens) and small bowel cancer (8 patients). RESULTS: The median frequency of PC was 0.25%. The expression of PD1 was <5% in 34 patients, 5-25% in 5 patients and 26-50% in 1 patient. The frequency of stromal CD8+ TILs was negative in 3 patients, <25% in 26, 26-50% in 10 and >50% in 1 patient, respectively. Intraepithelial CD8+ TILs were not detectable in 14, <25% in 24 and 26-50% in 2 patients, respectively. Statistically, the frequency of PC and PD-1 positivity were significantly associated (p=0.004). An association between the PC frequency and intraepithelial CD8+ TILs was of borderline statistical significance (p=0.059). An index combining the frequency of PC and stromal CD8+ TILs, but not the combination of frequency of PC and intraepithelial CD8+ TILs, was of borderline prognostic significance (p=0.067). CONCLUSIONS: The present study provides the first data on the potential association and combined prognostic significance of frequency of PC, PD-1 and CD8+ TILs in patients with intestinal cancer.

Department of Oncology 1st Faculty of Medicine Charles University and Thomayer Hospital Prague Czech Republic