The programmed death-ligand 1 (PD-L1) has an important role in anticancer immunity. The aim of our study was to examine the expression and prognostic value of PD-L1 in tumor and immune cells in patient with squamous cell carcinoma of oral cavity (OCSCC).
We detected tumor samples of 60 patients with OCSCC with stage I - IVB (37 men, 23 women; median age 59). We examined demographic data, clinical stage, tumor morphological characteristics and expression of PD-L1 in tumor and immune cells (clone BCDdx1020) by immunohistochemistry (55 samples were acceptable).
The expression level in tumor cells varied from 0% to 70%: in 24 (43,64%) samples expression of PD-L1% were negative (0%), in 9 (16,36%) - from 1 to 4% (low rate), in 17 (30,91%) - from 5 to 49% (moderate rate) and in 5 (9,1%) - more than 50% (high). In immune cells expression of PD-L1 varied from 0% to 15%: in 7 (12,73%) samples - negative (0%), in 30 (54,55%) - from 1 to 4% (low), in 13 (23,64%) - from 5 to 9% (moderate) and in 5(9,10%) - >10% (high). In 5 samples with high level PD-L1 expression in tumor expression PD-L1 in immune cells was negative. Median OS of patients with PD-L1-negative' tumor was 17 mo (95% CI 8-185), with low rate (1-4%) of PD-L1 expression - 9 mo (95% CI 2-36), with moderate rate (5-49%) - 13 mo (95% CI 7,5-19) and median OS in patients with high rate (>50%) not reached for this time and mean of OS is 55 mo (σ = 14,722) (95% CI 26-84). Median OS of patients with negative PD-L1-status in immune cells was 12 mo (95% CI 4-185), with low rate (1-4%) PD-L1 in immune cells - 13 mo (95% CI 7,5-34,5), with moderate rate (5-9%) - 15 mo (95%CI 9-15) and with hight rate (>10%) - 17 mo (95%CI 3-36) with strong trend of increasing OS with rise of PD-L1 expression in immune cells.
PD-L1 expression in tumor and immune cells are favourable prognostic factors for oral cavity squamous cell carcinoma.
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All authors have declared no conflicts of interest.