Endemic nasopharyngeal carcinoma (NPC) is closely associated with the Epstein–Barr virus (EBV), which contributes to tumor development and influences the tumor immune microenvironment (TIME) in NPC. Natural killer (NK) cells, as part of the innate immune system, play a crucial role in responding to viral infections and malignant cell transformations. Notably, NK cells possess a unique ability to target tumor cells independent of major histocompatibility complex class I (MHC I) expression. This means that MHC I-deficient tumor cells, which can escape from effective T cell attack, are susceptible to NK-cell-mediated killing. The activation of NK cells is determined by the signals generated through inhibitory and activating receptors expressed on their surface. Understanding the role of NK cells in the complex TIME of EBV⁺ NPC is of utmost importance. In this review, we provide a comprehensive summary of the current understanding of NK cells in NPC, focusing on their subpopulations, interactions, and cytotoxicity within the TIME. Moreover, we discuss the potential translational therapeutic applications of NK cells in NPC. This review aims to enhance our knowledge of the role of NK cells in NPC and provide valuable insights for future investigations.

Background: The chemokine CCL5 exhibits a complex role in cancer immunotherapy, yet its dual immunomodulatory functions in non-small cell lung cancer (NSCLC) remain poorly understood. Methods and Results: Based on a newly analyzed clinical cohort of 33 advanced NSCLC patients receiving anti-PD-1 therapy combined with platinum-based chemotherapy, we found that elevated baseline peripheral blood CCL5 levels significantly predicted shorter overall survival (27.6 months vs. not reached, HR = 2.779, p = 0.038) and a higher incidence of immune-related pneumonitis (p = 0.0072). These clinical observations were supported by the re-analysis of a previously published single-cell RNA sequencing (scRNA-seq) dataset (n = 8), which indicated that high CCL5 expression in peripheral blood T/NK cells was associated with a lower major pathological response (p = 0.029). To explore the underlying mechanisms, we conducted detailed analyses using a large, publicly available tumor scRNA-seq dataset (GSE243013, n = 234). These analyses revealed that high intratumoral CCL5 simultaneously promoted the recruitment of both immune effector cells (CD8⁺ T cells, NK cells) and immunosuppressive populations (Tregs, MDSCs). This paradoxical immune landscape correlated with elevated immune checkpoint expression and significantly higher TIDE scores (1.47 vs. 0.83, p < 0.001). CellChat and SCENIC network analyses identified intensified T cell–myeloid communication and key transcription factors (e.g., FOXP3, EOMES) mediating this dichotomy. Conclusions: This hypothesis-generating study raises the possibility that CCL5 orchestrates paradoxical immune responses and may serve as a biomarker in NSCLC. Further validation in larger prospective, independent cohorts is required.

Clear cell renal cell carcinoma (ccRCC) remains a challenging malignancy to treat, with immune checkpoint inhibitors (ICIs) revolutionizing patient management. This pilot study, evaluated the efficacy and safety of combination therapy comprising camrelizumab, an anti-PD-1 antibody, and autologous cytokine-induced killer (CIK) cell therapy in patients with refractory ccRCC. Twenty-one patients with refractory ccRCC were randomly assigned to receive either camrelizumab monotherapy (control group, n = 12) or camrelizumab combined with CIK cell re-transfusion (trial group, n = 9). Due to early termination (21 of 60 planned patients), all endpoints were exploratory. The objective response rate (ORR) was numerically higher in the combination group (55.6% vs. 41.7%; odds ratio 1.75, 95% confidence interval [CI]: 0.32–9.51), but not statistically significant. Median progression-free survival (PFS) was 28.5 vs. 8.67 months (hazard ratio [HR] 0.40, 95% CI: 0.12–1.34), and median overall survival (OS) was not reached vs. 57.47 months (HR 0.48, 95% CI: 0.09–2.53). One patient in the trial group achieved a complete metabolic response (CMR). The combination was well-tolerated without new safety signals. Exploratory analysis suggested that higher baseline PD-1 expression on CD8⁺ T cells might be associated with a better response, and the frequency of PD-1 positive cells tended to decrease after camrelizumab administration. The addition of CIK cell therapy to anti-PD-1 antibody showed signals of potential benefit in refractory ccRCC with a tolerable safety profile. This pilot study suggests the combination approach appears feasible and warrants investigation in larger trials in pretreated ccRCC patients. Registry: ClinicalTrials.gov, TRN: NCT03987698, Registration date: 17 June 2019.