Poor Prognosis and Therapeutic Responses in LILRB1-Expressing M2 Macrophages-Enriched Gastric Cancer Patients

Myeloid subsets impede the efficacy of anti-PD1 therapy in patients with advanced gastric cancer (WJOG10417GTR study)

BACKGROUND

Gastric cancer (GC) is one of the most common and deadly malignant diseases worldwide. Despite revolutionary advances, the therapeutic efficacy of anti-PD1/PDL1 monoclonal antibodies in advanced GC is still low due to the emergence of innate and acquired resistance to treatment. Myeloid cells represent the majority of human immune cells. Therefore, their increase, decrease, and abnormality could have a significant impact on the patient's immune system and the progression of cancer, and reprogramming, inhibiting, and eliminating the tumor-supportive types may improve the immunological situation and efficacy of immunotherapy. However, the significance of myeloid cells in anti-PD1/PDL1 therapy remains unclear in GC. In the WJOG10417GTR study on GC, we sought to identify myeloid determinants that could predict anti-PD1 therapeutic efficacy and also serve as potential therapeutic targets.

METHODS

We collected tumor tissues and peripheral blood from 96 patients with advanced GC before and 1 month after anti-PD1 nivolumab monotherapy, and the isolated whole leucocytes were analyzed by flow cytometry for various immune cell populations, including many myeloid subsets. Then, the relationship between the cellular levels and progression-free survival (PFS) or overall survival (OS) was statistically analyzed.

RESULTS

We found that high levels of several myeloid subsets expressing molecules that have been targeted in drug discovery but not yet approved for clinical use were significantly associated with shorter PFS/OS as compared with low levels: PDL1+ and CTLA4+ myeloid subsets within tumors at baseline, PDL1+, B7H3+ and CD115+ myeloid subsets in peripheral blood at baseline, and LAG3+, CD155+ and CD115+ myeloid subsets in peripheral blood at post-treatment.

CONCLUSIONS

This study revealed that these myeloid subsets are significant risk factors in nivolumab therapy for advanced GC. Targeting them may be useful as diagnostic biomarkers to predict potential anti-PD1 therapeutic efficacy, and also as therapeutic targets for accelerating the development of new drugs to improve clinical outcomes in immunotherapy for GC.

Tumor microenvironment of Burkitt lymphoma: different immune signatures with different clinical behavior

ABSTRACT

Burkitt lymphoma (BL) is characterized by a tumor microenvironment (TME) in which macrophages represent the main component, determining a distinct histological appearance known as "starry sky" pattern. However, in some instances, BL may exhibit a granulomatous reaction that has been previously linked to favorable prognosis and spontaneous regression. The aim of our study was to deeply characterize the immune landscape of 7 cases of Epstein-Barr virus-positive (EBV+) BL with granulomatous reaction compared with 8 cases of EBV+ BL and 8 EBV-negative (EBV-) BL, both with typical starry sky pattern, by Gene expression profiling performed on the NanoString nCounter platform. Subsequently, the data were validated using multiplex and combined immunostaining. Based on unsupervised clustering of differentially expressed genes, BL samples formed 3 distinct clusters differentially enriched in BL with a diffuse granulomatous reaction (cluster 1), EBV+ BL with typical starry sky pattern (cluster 2), EBV- BL with typical "starry sky" (cluster 3). We observed variations in the immune response signature among BL with granulomatous reaction and BL with typical "starry sky," both EBV+ and EBV-. The TME signature in BL with diffuse granulomatous reaction showed a proinflammatory response, whereas BLs with "starry sky" were characterized by upregulation of M2 polarization and protumor response. Moreover, the analysis of additional signatures revealed an upregulation of the dark zone signature and epigenetic signature in BL with a typical starry sky. Tumor-associated macrophages and epigenetic regulators may be promising targets for additional therapies for BL lymphoma, opening novel immunotherapeutic strategies.

MHC1/LILRB1 axis as an innate immune checkpoint for cancer therapy

Immune checkpoint blockades (ICBs) have revolutionized cancer therapy through unleashing anti-tumor adaptive immunity. Despite that, they are usually effective only in a small subset of patients and relapse can occur in patients who initially respond to the treatment. Recent breakthroughs in this field have identified innate immune checkpoints harnessed by cancer cells to escape immunosurveillance from innate immunity. MHC1 appears to be such a molecule expressed on cancer cells which can transmit a negative signal to innate immune cells through interaction with leukocyte immunoglobulin like receptor B1 (LILRB1). The review aims to summarize the current understanding of MHC1/LILRB1 axis on mediating cancer immune evasion with an emphasis on the therapeutic potential to block this axis for cancer therapy. Nevertheless, one should note that this field is still in its infancy and more studies are warranted to further verify the effectiveness and safety in clinical as well as the potential to combine with existing immune checkpoints.

Perspectives of targeting LILRB1 in innate and adaptive immune checkpoint therapy of cancer

Immune checkpoint blockade is a compelling approach in tumor immunotherapy. Blocking inhibitory pathways in T cells has demonstrated clinical efficacy in different types of cancer and may hold potential to also stimulate innate immune responses. A novel emerging potential target for immune checkpoint therapy is leukocyte immunoglobulin-like receptor subfamily B member 1 (LILRB1). LILRB1 belongs to the superfamily of leukocyte immunoglobulin-like receptors and exerts inhibitory functions. The receptor is expressed by a variety of immune cells including macrophages as well as certain cytotoxic lymphocytes and contributes to the regulation of different immune responses by interaction with classical as well as non-classical human leukocyte antigen (HLA) class I molecules. LILRB1 has gained increasing attention as it has been demonstrated to function as a phagocytosis checkpoint on macrophages by recognizing HLA class I, which represents a 'Don't Eat Me!' signal that impairs phagocytic uptake of cancer cells, similar to CD47. The specific blockade of the HLA class I:LILRB1 axis may provide an option to promote phagocytosis by macrophages and also to enhance cytotoxic functions of T cells and natural killer (NK) cells. Currently, LILRB1 specific antibodies are in different stages of pre-clinical and clinical development. In this review, we introduce LILRB1 and highlight the features that make this immune checkpoint a promising target for cancer immunotherapy.

Elevated LILRB1 expression predicts poor prognosis and is associated with tumor immune infiltration in patients with glioma

BACKGROUND

Leukocyte immunoglobulin-like receptor subfamily B1 (LILRB1) is regarded as an inhibitory molecule. However, the importance of LILRB1 expression in glioma has not yet been determined. This investigation examined the immunological signature, clinicopathological importance and prognostic value of LILRB1 expression in glioma.

METHODS

We used data from the UCSC XENA database, the Cancer Genome Atlas (TCGA) database, the Chinese Glioma Genome Atlas (CGGA) database, the STRING database, the MEXPRESS database and our clinical glioma samples to perform bioinformatic analysis and used vitro experiments to examine the predictive value and potential biological roles of LILRB1 in glioma.

RESULTS

Higher LILRB1 expression was considerably present in the higher WHO grade glioma group and was linked to a poorer prognosis in patients with glioma. Gene set enrichment analysis (GSEA) revealed that LILRB1 was positively correlated with the JAK/STAT signaling pathway. LILRB1 combined with tumor mutational burden (TMB) and microsatellite instability (MSI) may be a promising indicator for the effectiveness of immunotherapy in patients with glioma. Increased LILRB1 expression was positively linked with the hypomethylation, M2 macrophage infiltration, immune checkpoints (ICPs) and M2 macrophage makers. Univariate and multivariate Cox regression analyses determined that increased LILRB1 expression was a standalone causal factor for glioma. Vitro experiments determined that LILRB1 positively enhanced the proliferation, migration and invasion in glioma cells. MRI images demonstrated that higher LILRB1 expression was related with larger tumor volume in patients with glioma.

CONCLUSION

Dysregulation of LILRB1 in glioma is correlated with immune infiltration and is a standalone causal factor for glioma.

Macrophage Biomarkers sCD163 and sSIRPα in Serum Predict Mortality in Sarcoma Patients

Most soft tissue sarcoma (STS) patients do not respond to traditional checkpoint inhibitor treatment, which may be due to infiltrating immunosuppressive tumour-associated macrophages. This study investigated the prognostic value of four serum macrophage biomarkers. Methods: Blood samples were taken from 152 patients with STS at the time of diagnosis; clinical data were prospectively collected. The concentrations of four macrophage biomarkers (sCD163, sCD206, sSIRPα, sLILRB1) were measured in serum, dichotomised based on median concentration, and evaluated either individually or when combined with established prognostic markers. Results: All macrophage biomarkers were prognostic of overall survival (OS). However, only sCD163 and sSIRPα were prognostic for recurrent disease (sCD163: hazard ratio (HR): 1.97 (95% CI: 1.10-3.51) and sSIRPα: HR: 2.09 (95% CI: 1.16-3.77)). A prognostic profile was made based on sCD163 and sSIRPα; it also included c-reactive protein and tumour grade. Patients with intermediate- or high-risk prognostic profiles (adjusted for age and tumour size) had a higher risk of recurrent disease compared to low-risk patients (HR: 2.64 (95% CI: 0.97-7.19)) and (HR 4.3 (95% CI: 1.62-11.47)), respectively. Conclusion: This study demonstrated that serum biomarkers of immunosuppressive macrophages were prognostic for OS; when combined with well-established markers of recurrence they allowed for a clinically relevant categorising of patients.

Identifying the key genes of Epstein-Barr virus-regulated tumour immune microenvironment of gastric carcinomas

The Epstein-Barr virus (EBV) is involved in the carcinogenesis of gastric cancer (GC) upon infection of normal cell and induces a highly variable composition of the tumour microenvironment (TME). However, systematic bioinformatics analysis of key genes associated with EBV regulation of immune infiltration is still lacking. In the present study, the TCGA and GEO databases were recruited to analyse the association between EBV infection and the profile of immune infiltration in GC. The weighted gene co-expression analysis (WGCNA) was applied to shed light on the key gene modules associated with EBV-associated immune infiltration in GC. 204 GC tissues were used to analysed the expression of key hub genes by using the immunohistochemical method. Real-time PCR was used to evaluate the association between the expression of EBV latent/lytic genes and key immune infiltration genes. Our results suggested that EBV infection changed the TME of GC mainly regulates the TIICs. The top three hub genes of blue (GBP1, IRF1, and LAP3) and brown (BIN2, ITGAL, and LILRB1) modules as representative genes were associated with EBV infection and GC immune infiltration. Furthermore, EBV-encoded LMP1 expression is account for the overexpression of GBP1 and IRF1. EBV infection significantly changes the TME of GC, and the activation of key immune genes was more dependent on the invasiveness of the whole EBV virion instead of single EBV latent/lytic gene expression.

Natural killer cells and immune-checkpoint inhibitor therapy: Current knowledge and new challenges

The discovery of immune checkpoints (ICs) and the development of specific blockers to relieve immune effector cells from this inhibiting mechanism has changed the view of anti-cancer therapy. In addition to cytotoxic T lymphocyte antigen 4 (CTLA4) and programmed death 1 (PD1), classical ICs of T lymphocytes and recently described also on a fraction of natural killer (NK) cells, several NK cell receptors, including killer immunoglobulin-like inhibitory receptors (KIRs) and NGK2A, have been recognized as checkpoint members typical of the NK cell population. This offers the opportunity of a dual-checkpoint inhibition approach, targeting classical and non-classical ICs and leading to a synergistic therapeutic effect. In this review, we will overview and discuss this new perspective, focusing on the most relevant candidates for this role among the variety of potential NK ICs. Beside listing and defining classical ICs expressed also by NK cells, or non-classical ICs either on T or on NK cells, we will address their role in NK cell survival, chronic stimulation or functional exhaustion, and the potential relevance of this phenomenon on anti-tumor immune response. Furthermore, NK ICs will be proposed as possible new targets for the development of efficient combined immunotherapy, not forgetting the relevant concerns that may be raised on NK IC blockade. Finally, the impact of epigenetic drugs in such a complex therapeutic picture will be briefly addressed.