Clinicopathological significance of PD-L1 expression in colorectal cancer: Impact of PD-L1 expression on pFOXO1 expression

Objective: This study aimed to evaluate the clinicopathological significance of PD-L1 expression and its impact on phospho-Forkhead box O 1 (pFOXO1) expression in colorectal cancer (CRC). Methods: Immunohistochemical analysis for PD-L1 and pFOXO1 was performed on 265 human CRC tissues. PD-L1 expression was evaluated in the tumor and immune cells. The impact of PD-L1 expression on survival was investigated in relation to the pattern of pFOXO1 expression. Results: PD-L1 was expressed in 25 (9.4%) and 41 (17.7%) patients in the tumor and immune cells of the 265 CRC tissues, respectively. PD-L1 expression in immune cells (I-PD-L1) was significantly correlated with less lymphatic invasion, lymph node metastasis, and distant metastasis and lower pT and pTNM stages. Additionally, there was a significant correlation between PD-L1 expression in tumor cells (T-PD-L1) and tumor location (right colon), but not the other clinicopathological characteristics. pFOXO1 expression was significantly lower in CRC with high I-PD-L1 expression than in CRC with low or negative I-PD-L1 expression. However, there was no significant correlation between pFOXO1 and T-PD-L1 expression in CRC. Patients with positive pFOXO1 and low or negative I-PD-L1 expression exhibited the worst survival among patients with CRC. Conclusion: Collectively, our results indicate that I-PD-L1 expression was significantly correlated with favorable tumor behaviors and better survival. In addition, patients with high I-PD-L1 and low pFOXO1 expressions had a favorable prognosis than those with other I-PD-L1 and pFOXO1 expression patterns.