Supporting data for "Systemic Immune Biomarkers Reflect the Local Tumor Immune Environment in Recurrent/Metastatic Nasopharyngeal Carcinoma"

Changes within the tumor immune microenvironment (TME) are often reflected in peripheral immune populations. Therein, development of biomarkers based on peripheral immune population phenotypes offers an opportunity to capture intratumoral dynamics. Here in we report development of a peripheral immune-based biomarker approach for Nasopharyngeal Carcinoma (R/M NPC). We focused on quantitating levels of peripheral CX3CR1+ CD8+ T cells with high clonal similarity to tumor-infiltrating counterparts and expression of the exclusive CX3CR1 ligand CX3CL1 in NPC models. We found that NPC tumor cell expression of CX3CL1 impacted the stemness and immunoregulatory polarization of CX3CR1+CD8+ T cells while also promoting their infiltration into the TME. Analysis of peripheral blood collected from 38 R/M NPC patients treated a bifunctional fusion protein bintrafusp alfa demonstrated that responders retained stable immune profiles, while non-responders experienced a decrease in CX3CR1+CD8+ T cells and an increase in monocytic myeloid derived suppressor cells (M-MDSCs). Additionally, we observed a significant correlation between tissue PD-L1 expression status and levels of soluble immune checkpoints. These findings suggest that CX3CR1+CD8+ T cells may serve as a potential predictive biomarker for immunotherapeutic outcomes in NPC.