ILT4 and its R20H variant as marker of poor prognosis in Spanish patients with colorectal cancer.

[BACKGROUND] Immune checkpoint blockade is proving beneficial for cancer treatment by stimulating the anti-tumor immune response. However, the lack of success in certain cancer types encourages the research of new potential targets. ILT4 (Immunoglobulin-like transcript 4) is a transmembrane protein that binds with high affinity to HLA-G molecules present on tumor cells, modulating responses mediated by monocytes, macrophages, and dendritic cells.

[OBJECTIVE] To compare ILT4 expression and the distribution of the LILRB2 rs383369 single nucleotide polymorphism (SNP), a R20H variant resulting in higher levels of ILT4 expression, in patients with colorectal adenocarcinoma of Spanish origin.

[METHODS] Seventy-three patients with colorectal adenocarcinoma were included in this study. ILT4 expression was assessed by immunohistochemistry and flow cytometry. Genotyping of the rs383369 SNP was performed by PCR-RFLP and further confirmed by Sanger sequencing. Associations were tested with clinical variables, histological differentiation, and survival outcomes.

[RESULTS] Flow cytometric analysis confirmed ILT4 expression in the peripheral blood mononuclear cells of patients with colorectal adenocarcinoma. Similarly, immunohistochemistry demonstrated a greater infiltrate of ILT4 + cells in tumor tissue samples compared to distal tissue. The frequency of the rs383369-C (20H) variant was increased in patients with lymph node infiltration, identifying the C allele as a risk variable for tumor progression towards nodal invasion and more severe disease (p-value = 0.035).

[CONCLUSIONS] Patients with colorectal tumors exhibit a high infiltrate of ILT4 + cells within the tumors, and the rs383369-C polymorphism is linked to greater pathological severity. These results support the involvement of ILT4 in the development of colorectal tumors, as well as its potential use as a biomarker and therapeutic target.