Profile of PD-1 and PD-L1 mRNA Expression in Peripheral Blood of Nasopharyngeal Carcinoma

Background: Programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) expression is associated with prognostic and respond to immunotherapy with immune checkpoint inhibitor in several solid malignancies. However, the prognostic roles of PD-1 and PD-L1 expression in nasopharyngeal carcinoma (NPC) are less clear. This study aims to investigate PD-1 and PD-L1 mRNA expression levels in peripheral blood of Indonesian NPC patients and its association with clinicopathological features.Materials and Methods: This study used blood samples of 21 NPC patients and 10 healthy volunteers as controls. Real-time polymerase chain reaction (PCR) was used to measure mRNA expression of PD-1 and PD-L1.Results: PD-1 mRNA expression levels were significantly lower in NPC patients (∆CT mean: 9.65±2.04) compared to healthy individuals (∆CT mean: 8.04±1.51) (p=0.031). In contrast, PD-L1 mRNA expression levels were higher in NPC patients (∆CT mean: 6.96±1.32) compared to healthy individuals (∆CT mean: 7.11±0.55), but the difference was not statistically significant (p=0.554). The expression of PD-1 was associated with tumour-node-metastasis (TNM) stage (p=0.030) but not associated with age (p=1.000), sex (p=1.000), body mass index (p=0.350), tumor stage (p=0.338), nodal stage (p=0.579), metastasis stage (p=0.371), and Eastern Cooperative Oncology Group (ECOG) status (p=0.228). Meanwhile PD-L1 expression was not associated with all clinicophatological features.Conclusion: The PD-1 mRNA expression levels were significantly lower, while PD-L1 expression levels were higher in NPC patients compared to healthy controls. PD-1 expression was correlated with TNM stage.Keywords: nasopharyngeal carcinoma, immune checkpoint inhibitors, PD-1, PD-L

Tumor microenvironment predicts local tumor extensiveness in PD-L1 positive nasopharyngeal cancer.

Tumor microenvironment have been implicated in many kind of cancers to hold an important role in determining treatment success especially with immunotherapy. In nasopharyngeal cancer, the prognostic role of this immune cells within tumor microenvironment is still doubtful. We conducted a study that included 25 nasopharyngeal cancer biopsy specimens to seek a more direct relationship between tumor infiltrating immune cells and tumor progression. Apart from that, we also checked the PD-L1 protein through immunohistochemistry. The PD-L1 was positively expressed in all our 25 samples with nasopharyngeal cancer WHO type 3 histology. Majority samples have >50% PD-L1 expression in tumor cells. We also found that denser local tumor infiltrating immune cells population have relatively much smaller local tumor volume. The inverse applied, with the mean local tumor volumes were 181.92 cm3 ± 81.45 cm3, 117.13 cm3 ± 88.72 cm3, and 55.13 cm3 ± 25.06 cm3 for mild, moderate, and heavy immune cells infiltration respectively (p = 0.013). Therefore, we concluded that tumor infiltrating immune cells play an important role in tumor progression, hence evaluating this simple and predictive factor may provide us with some valuable prognostic information