Predictive value of CD8/FOXP3 ratio combined with PD‐L1 expression for radiosensitivity in patients with squamous cell carcinoma of the larynx receiving definitive radiation therapy

Background Little is known about immune‐related radiosensitivity in patients with squamous cell carcinoma of the larynx (SCC‐L) treated with radiation therapy (RT). Methods We retrospectively reviewed 91 patients with SCC‐L treated with RT or chemoradiation therapy and performed immunohistochemical examination to analyze PD‐L1 level on tumor cells, CD4+ tumor‐infiltrating lymphocytes (TILs), CD8+TIL, and FOXP3+TIL using pretreated biopsy specimens. The association between these immune‐related parameters and radiosensitivity was evaluated. Results Multivariate analyses showed that high CD8/FOXP3 ratio combined with negative PD‐L1 expression was an independent and significant favorable predictive factor for local control, compared with the other groups. Conclusions We showed that high CD8/FOXP3 ratio combined with negative PD‐L1 expression might be a useful biomarker of radiosensitivity in patients with SCC‐L receiving definitive RT. We propose that coassessment of CD8/FOXP3 ratio and PD‐L1 expression level in tumor cells can help predict potential radiosensitivity in patients with SCC‐L.