Yoshikawa K, Ishida M, Yanai H, et al. - Researchers aimed at determining the significance of CD155 expression in patients with triple-negative breast cancer, and the correlation between CD155 and programmed death-ligand 1 (PD-L1) expression. Among 61 patients with triple-negative breast cancer, 41.0% showed CD155 expression. No correlation of its expression with any of the clinicopathological factors was observed. In addition, there was no correlation of CD155 expression with PD-L1 expression in tumor cells using the 73–10 assay, but CD155 expression was noted to be significantly correlated with PD-L1 expression in tumor cells using the SP142 assay, with 59.0% of patients demonstrating CD155 and/or PD-L1 expression in tumor cells using the 73–10 assay, and 63.3% of patients exhibiting CD155 and/or PD-L1 expression in immune cells using the SP142 assay. As per findings, CD155 expression may enhance the pool of candidates with TNBC who could benefit from antitumor immunotherapy.