In the past, immune memory was considered an exclusive feature of the adaptive immune system. However, accumulating evidence suggests that the innate immune system, the most primitive and fundamental component of immunity, can mount more robust responses to non-specific stimuli following prior exposure to different types of initial stimuli, a phenomenon known as trained immunity. Trained immunity has been extensively studied in diverse disease contexts, including infectious diseases, autoimmune disorders, and chronic inflammatory conditions. Notably, significant advancements have been made in recent years in understanding the roles and therapeutic potential of trained immunity in oncology. This review aims to explore the multifaceted roles of trained immunity across different cancer types, providing a comprehensive summary of the pertinent stimuli and associated molecular mechanisms. Additionally, we evaluate the clinical applications of various trained immunity stimuli in cancer therapy and offer perspectives on future directions for integrating trained immunity into cancer treatment strategies.

Dyslipidemia was associated with gastric adenocarcinoma or neuroendocrine tumors, but its role in a more malignant entity, gastric cancer with neuroendocrine immunophenotypes (GCNEI), was unclarified. This study sought to explore the relationship between serum lipid levels and the biological behaviors of gastric cancer with neuroendocrine immunophenotypes (GCNEI). Patients with neuroendocrine carcinoma (NEC), GC with NEC components (GC-NEC), or GC expressing NE marker(s) but no NE morphology (GC-NENM) were enrolled from three centers. Their preoperative serum lipid levels, demographic, and clinicopathological information were analyzed and compared with those of patients with pure adenocarcinoma (PAC) or a background population selected from 10,061 health-check people by propensity-score matching. A total of 342 GCNEI patients were enrolled. Compared with the background population, total cholesterol (TCHO) and high-density lipoprotein cholesterol (HDL-C) levels were lower in GCNEI. Compared with PAC, GC-NENM and GC-NEC showed lower triglyceride (TG) levels, while, carcinoma with NE morphology showed higher low-density lipoprotein cholesterol (LDL-C) levels. Among GCNEI subtypes, GC-NEC differed from the others by higher LDL-C and non-HDL-C levels. A higher LDL-C level and(or) lower TG, HDL-C levels correlated to higher stages or large tumor sizes in GC-NENM, and a lower HDL-C level correlated to large tumor sizes in GC-NEC. A higher LDL-C level, lower TG, HDL-C, and non-HDL levels increased the risk of GC-NEC, and lower TG, and HDL-C levels increased the risk of GC-NENM and NEC. GCNEI had distinct and heterogeneous serum lipid patterns, which correlated to tumor development and progression.

Zou Y, et al. J Gastric Cancer. 2019 Jan;19:e9. https://doi.org/10.5230/jgc.2019.19.e9

Purpose: This study sought to characterize the tumor immune microenvironment (TIME) of lung adenocarcinomas with ALK rearrangements (ALK+ LUAD), which responds poorly to immune checkpoint inhibitors (ICIs) therapy. Materials and methods: Immune score evaluation and immunohistochemical (IHC) validation of B cells, cytotoxic, helper, regulatory T cells, dendritic cells, and tumor-associated macrophages were performed on the TCGA cohort and the whole tissue sections of our matched surgical samples, respectively, between ALK+ and ALK− LUAD. The formation and spatial organization of TLS, intra- and extra-TLS immune cell features, and tumor PD-L1 expression were analyzed independently. Results: Immune scores and TLS-signature gene levels were found to be lower in ALK+ TCGA LUAD. Quantitative IHC comparison confirmed the lower densities of TLS (0.10/mm² vs. 0.34/mm², p = 0.026) and intra-TLS immune cells (CD4+ helper T cells: 57.65/mm² vs. 274.82/mm², p = 0.026; CD8+ cytotoxic T cells: 22.46/mm² vs. 172.83/mm², p = 0.018; and CD20+ B cells: 36.08/mm² vs. 207.29/mm², p = 0.012) in ALK+ surgical samples. The TLS formation was negatively correlated with tumor progression in ALK+ tumors. The proportion of intra-TLS CD8+ cytotoxic T cells was the independent protective factors of node metastasis (HR: 0.599, 95% CI: 0.414–0.868, p = 0.007), and the density of intra-TLS CD20+ B cells was the independent protective factor of pStage (HR: 0.641, 95% CI: 0.446–0.922, p = 0.016). Tumors with intratumoral TLS showed significantly higher expression of PD-L1 (p = 0.029). Conclusion: ALK+ LUAD harbored a cold TIME featured by decreased TLS formation, which closely correlated to tumor progression and might contribute to the poor efficiency of ICIs.

Background/Objectives: Tumor-draining lymph nodes (TDLNs) play a critical role in shaping a pre-metastatic and immunosuppressive niche that facilitates tumor dissemination. However, a robust in vivo model that recapitulates regional lymph node and distant metastasis remains elusive. We sought to establish and characterize an animal model that reliably mimics spontaneous human melanoma progression from primary tumor to regional lymph node and distant organ metastasis. Methods: B16F10-Luc2 melanoma cells were subcutaneously implanted from the hock area into the lower medial thigh of C57BL/6J mice to establish a metastatic melanoma mouse model with reliable regional lymph node metastasis and distant metastasis. Tumor growth was monitored over time. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and bioluminescence imaging (BLI) were used to track lymph node and lung metastases in vivo. Immunocytochemistry (IHC) was performed to confirm the metastatic melanoma cells in tissues. The immune landscape of metastatic lymph nodes was characterized by Cytometry by Time-Of-Flight (CyTOF). Results: This implantation strategy resulted in consistent primary tumor growth accompanied by reproducible metastasis to ipsilateral inguinal lymph nodes (IILN) and subsequent lung metastasis. Multi-modal imaging (PET/CT and BLI) enabled non-invasive monitoring of metastatic progression in vivo. Histological analyses confirmed melanoma cell infiltration in lymph nodes and lung tissues. Notably, CyTOF profiling revealed a distinct immunological remodeling within the TDLN, characterized by immunosuppressive phenotypes in the tumor-draining ipsilateral inguinal lymph node (IILN) compared with naïve nodes, indicative of a potential immunotolerant environment in tumor-bearing mice associated with metastatic progression. Conclusions: We present a reproducible and clinically relevant syngeneic melanoma mouse model that recapitulates lymphatic dissemination to regional lymph nodes and distant lung metastasis, and mimics the immunosuppressive phenotypes in the tumor-draining lymph node microenvironment seen in human melanoma patients. This model provides a valuable platform for investigating the mechanisms of lymphatic metastasis and the immunological dynamics of TDLNs, with potential applications in evaluating therapeutic strategies targeting metastatic progression.