Updated Immunotherapy for Gastric Cancer

C3+ cancer-associated fibroblasts promote tumor growth and therapeutic resistance in gastric cancer via activation of the NF-κB signaling pathway

BACKGROUND

Gastric cancer (GC) remains one of the most lethal malignancies globally, with limited therapeutic options. Cancer-associated fibroblasts (CAFs), a diverse population of stromal cells within the tumor microenvironment (TME), play a central role in tumor progression and therapeutic resistance. However, the specific markers identifying tumor-promoting CAF subsets in GC have yet to be fully characterized.

METHODS

Through animal studies and RNA sequencing, complement C3 (C3) emerged as a key marker linked to tumor-promoting CAF subsets. Single-cell sequencing and multiplex immunofluorescence staining confirmed that C3 expression is predominantly localized within CAFs. Independent cohort analyses demonstrated a strong association between elevated levels of C3+ CAFs and poor clinical outcomes in GC patients. To further investigate, small interfering RNA (siRNA)-mediated knockdown of C3 in CAFs was employed in vitro, with subsequent experiments, including cell migration assays, cell viability assays, and immunofluorescence, revealing significant functional impacts.

RESULTS

C3 secreted by CAFs promoted Epithelial-mesenchymal transition (EMT) and accelerated cancer cell migration. Patients with minimal C3+ CAF infiltration exhibited a higher probability of deriving therapeutic benefit from adjuvant treatments. Furthermore, C3+ CAFs were associated with immunosuppressive effects and an immune-evasive microenvironment marked by CD8 + T cell dysfunction. A lower prevalence of C3+ CAFs correlated with improved responsiveness to immunotherapy in GC patients. Enrichment analysis highlighted pronounced activation of the NF-κB signaling pathway in C3+ CAFs relative to their C3- counterparts, supported by elevated phosphorylation levels of IKK, IκBα, and p65 in C3+ CAFs compared to both C3- CAFs and normal fibroblasts (NFs). Silencing p65 nuclear translocation in CAFs through siRNA significantly suppressed C3 secretion.

CONCLUSIONS

The study suggests that NF-κB pathway-mediated CAF activation enhances C3 secretion, driving EMT, migration, chemoresistance, and immune evasion in GC progression. Targeting the NF-κB/C3 signaling axis in CAFs may offer a viable therapeutic strategy for GC management.

Novel immunotherapeutic approaches in gastric cancer

Gastric cancer is a malignant tumor that ranks third in cancer-related deaths worldwide. Early-stage gastric cancer can often be effectively managed through surgical resection. However, the majority of cases are diagnosed in advanced stages, where outcomes with conventional radiotherapy and chemotherapy remain unsatisfactory. Immunotherapy offers a novel approach to treating molecularly heterogeneous gastric cancer by modifying the immunosuppressive tumor microenvironment. Immune checkpoint inhibitors and adoptive cell therapy are regarded as promising modalities in cancer immunotherapy. Food and Drug Administration-approved programmed death-receptor inhibitors, such as pembrolizumab, in combination with chemotherapy, have significantly extended overall survival in gastric cancer patients and is recommended as a first-line treatment. Despite challenges in solid tumor applications, adoptive cell therapy has demonstrated efficacy against various targets in gastric cancer treatment. Among these approaches, chimeric antigen receptor-T cell therapy research is the most widely explored and chimeric antigen receptor-T cell therapy targeting claudin18.2 has shown acceptable safety and robust anti-tumor capabilities. However, these advancements primarily remain in preclinical stages and further investigation should be made to promote their clinical application. This review summarizes the latest research on immune checkpoint inhibitors and adoptive cell therapy and their limitations, as well as the role of nanoparticles in enhancing immunotherapy.

Targeted and combination immunotherapies using biologics for gastric cancer: the state-of-the-art

INTRODUCTION

Gastric adenocarcinoma (GAC) remains a prevalent cancer worldwide and its incidence is increasing in South America. The heterogenous nature of GAC makes advances in management challenging.

AREAS COVERED

Despite challenges, recent therapeutic targets are individualizing treatment. For localized disease with microsatellite-instability-high/deficient mismatch repair, immunotherapy is now an adopted practice. In the advanced unresectable setting, those harboring human epidermal growth factor receptor-2 (HER2) expression continue to be a separate entity.

EXPERT OPINION

Future targets are developing. Among these include claudin 18.2 (CLDN18.2), fibroblast growth factor receptor 2b (FGFR2b), and trophoblast cell surface antigen-2 (TROP-2). FDA approval of zolbetuximab's, an anti-CLDN 18.2 monoclonal antibody, is expected soon. Additionally, bemarituzumab, ananti-FGFR2b monoclonal antibody, has shown improvements in combination with chemotherapy in those with HER2 negative GAC with FGFR2 overexpression. This combination is now being investigated in a phase 3 trial. Lastly, TROP-2 has emerged as an exciting solid tumor target and study is expected in GAC. All three of these therapeutic targets have seen an abundance of drug development in recent years, and we anticipate newer targeted agents driving therapeutic decisions in GAC in the coming years.

Theranostic Approaches for Gastric Cancer: An Overview of In Vitro and In Vivo Investigations

Gastric cancer (GC) is the second most common cause of cancer-related death worldwide and a serious public health concern. This high death rate is mostly caused by late-stage diagnoses, which lead to poor treatment outcomes. Radiation immunotherapy and targeted therapies are becoming increasingly popular in GC treatment, in addition to surgery and systemic chemotherapy. In this review, we have focused on both in vitro and in vivo research, which presents a summary of recent developments in targeted therapies for gastric cancer. We explore targeted therapy approaches, including integrin receptors, HER2, Claudin 18, and glutathione-responsive systems. For instance, therapies targeting the integrin receptors such as the αvβ3 and αvβ5 integrins have shown promise in enhancing diagnostic precision and treatment efficacy. Furthermore, nanotechnology provides novel approaches to targeted drug delivery and imaging. These include glutathione-responsive nanoplatforms and cyclic RGD peptide-conjugated nanoparticles. These novel strategies seek to reduce systemic toxicity while increasing specificity and efficacy. To sum up, the review addresses the significance of personalized medicine and advancements in gastric cancer-targeted therapies. It explores potential methods for enhancing gastric cancer prognosis and treatment in the future.

CPT1C-positive cancer-associated fibroblast facilitates immunosuppression through promoting IL-6-induced M2-like phenotype of macrophage

Cancer-associated fibroblasts (CAFs) exhibit remarkable phenotypic heterogeneity, with specific subsets implicated in immunosuppression in various malignancies. However, whether and how they attenuate anti-tumor immunity in gastric cancer (GC) remains elusive. CPT1C, a unique isoform of carnitine palmitoyltransferase pivotal in regulating fatty acid oxidation, is briefly indicated as a protumoral metabolic mediator in the tumor microenvironment (TME) of GC. In the present study, we initially identified specific subsets of fibroblasts exclusively overexpressing CPT1C, hereby termed them as CPT1C+CAFs. Subsequent findings indicated that CPT1C+CAFs fostered a stroma-enriched and immunosuppressive TME as they correlated with extracellular matrix-related molecular features and enrichment of both immunosuppressive subsets, especially M2-like macrophages, and multiple immune-related pathways. Next, we identified that CPT1C+CAFs promoted the M2-like phenotype of macrophage in vitro. Bioinformatic analyses unveiled the robust IL-6 signaling between CPT1C+CAFs and M2-like phenotype of macrophage and identified CPT1C+CAFs as the primary source of IL-6. Meanwhile, suppressing CPT1C expression in CAFs significantly decreased IL-6 secretion in vitro. Lastly, we demonstrated the association of CPT1C+CAFs with therapeutic resistance. Notably, GC patients with high CPT1C+CAFs infiltration responded poorly to immunotherapy in clinical cohort. Collectively, our data not only present the novel identification of CPT1C+CAFs as immunosuppressive subsets in TME of GC, but also reveal the underlying mechanism that CPT1C+CAFs impair tumor immunity by secreting IL-6 to induce the immunosuppressive M2-like phenotype of macrophage in GC.

A novel biomarker associated with EBV infection improves response prediction of immunotherapy in gastric cancer

BACKGROUND

Novel biomarkers are required in gastric cancer (GC) treated by immunotherapy. Epstein-Barr virus (EBV) infection induces an immune-active tumor microenvironment, while its association with immunotherapy response is still controversial. Genes underlying EBV infection may determine the response heterogeneity of EBV + GC. Thus, we screened hub genes associated with EBV infection to predict the response to immunotherapy in GC.

METHODS

Prognostic hub genes associated with EBV infection were screened using multi-omic data of GC. EBV + GC cells were established and confirmed by EBV-encoded small RNA in situ hybridization (EBER-ISH). Immunohistochemistry (IHC) staining of the hub genes was conducted in GC samples with EBER-ISH assay. Infiltrating immune cells were stained using immunofluorescence.

RESULTS

CHAF1A was identified as a hub gene in EBV + GC, and its expression was an independent predictor of overall survival (OS). EBV infection up-regulated CHAF1A expression which also predicted EBV infection well. CHAF1A expression also predicted microsatellite instability (MSI) and a high tumor mutation burden (TMB). The combined score (CS) of CHAF1A expression with MSI or TMB further improved prognostic stratification. CHAF1A IHC score positively correlated with the infiltration of NK cells and macrophages M1. CHAF1A expression alone could predict the immunotherapy response, but its CS with EBV infection, MSI, TMB, or PD-L1 expression showed better effects and improved response stratification based on current biomarkers.

CONCLUSIONS

CHAF1A could be a novel biomarker for immunotherapy of GC, with the potential to improve the efficacy of existing biomarkers.

TAMs and PD-1 Networking in Gastric Cancer: A Review of the Literature

BACKGROUND

Gastric cancer (GC) is one of the most common and aggressive types of cancer. Immune checkpoint inhibitors (ICIs) have proven effective in treating various types of cancer. The use of ICIs in GC patients is currently an area of ongoing research. The tumor microenvironment (TME) also seems to play a crucial role in cancer progression. Tumor-associated macrophages (TAMs) are the most abundant population in the TME. TAMs are capable of displaying programmed cell death protein 1 (PD-1) on their surface and can form a ligand with programmed death ligand 1 (PD-L1), which is found on the surface of cancer cells. Therefore, it is expected that TAMs may significantly influence the immune response related to immune checkpoint inhibitors (ICIs).

AIM OF THE STUDY

Understanding the role of TAMs and PD-1/PD-L1 networking in GC.

METHODS

A systematic review of published data was performed using MEDLINE (PubMed), Embase, and Cochrane databases. We retrieved articles investigating the co-existence of TAMs and PD-1 in GC and the prognosis of patients expressing high levels of PD-1+ TAMs.

RESULTS

Ten articles with a total of 2277 patients were included in the systematic review. The examined data suggest that the expression of PD-L1 has a positive correlation with the infiltration of TAMs and that patients who express high levels of PD-1+ TAMs may have a worse prognosis than those who express low levels of PD-1+ TAMs.

CONCLUSIONS

TAMs play a pivotal role in the regulation of PD-1/PD-L1 networking and the progression of GC cells. Nevertheless, additional studies are needed to better define the role of TAMs and PD-1/PD-L1 networking in GC.

Association of genes in hereditary metabolic diseases with diagnosis, prognosis, and treatment outcomes in gastric cancer

Background

Aberrant metabolism is a major hallmark of cancers and hereditary diseases. Genes associated with inborn metabolic errors may also play roles in cancer development. This study evaluated the overall impact of these genes on gastric cancer (GC).

Methods

In total, 162 genes involved in 203 hereditary metabolic diseases were identified in the Human Phenotype Ontology database. Clinical and multi-omic data were acquired from the GC cohort of the Affiliated Hospital of Jiangsu University and other published cohorts. A 4-gene and 32-gene signature was established for diagnosis and prognosis or therapeutic prediction, respectively, and corresponding abnormal metabolism scores (AMscores) were calculated.

Results

The diagnostic AMscore showed high sensitivity (0.88-1.00) and specificity (0.89-1.00) to distinguish between GC and paired normal tissues, with area under the receiver operating characteristic curve (AUC) ranging from 0.911 to 1.000 in four GC cohorts. The prognostic or predictive AMscore was an independent predictor of overall survival (OS) in five GC cohorts and a predictor of the OS and disease-free survival benefit of postoperative chemotherapy or chemoradiotherapy in one GC cohort with such data. The AMscore adversely impacts immune biomarkers, including tumor mutation burden, tumor neoantigen burden, microsatellite instability, programmed death-ligand 1 protein expression, tumor microenvironment score, T cell receptor clonality, and immune cell infiltration detected by multiplex immunofluorescence staining. The AUC of the AMscore for predicting immunotherapy response ranging from 0.780 to 0.964 in four cohorts involving GC, urothelial cancer, melanoma, and lung cancer. The objective response rates in the low and high AMscore subgroups were 78.6% and 3.2%, 40.4% and 7%, 52.6% and 0%, and 72.7% and 0%, respectively (all p<0.001). In cohorts with survival data, a high AMscore was hazardous for OS or progression-free survival, with hazard ratios ranged from 5.79 to 108.59 (all p<0.001). Importantly, the AMscore significantly improved the prediction of current immune biomarkers for both response and survival, thus redefining the advantaged and disadvantaged immunotherapy populations.

Conclusions

Signatures based on genes associated with hereditary metabolic diseases and their corresponding scores could be used to guide the diagnosis and treatment of GC. Therefore, further validation is required.

Regulatory T cells in gastric cancer: Key controllers from pathogenesis to therapy

Gastric cancer (GC) is a highly aggressive malignancy that remains a significant contributor to cancer-related mortality worldwide, despite a decline in incidence in recent years. Early-stage GC poses a diagnostic challenge due to its asymptomatic nature, leading to poor prognoses for most patients. Conventional treatment approaches, including chemotherapy and surgery, have shown limited efficacy in improving outcomes for GC patients. The advent of immune checkpoint inhibitors (ICIs) has revolutionized cancer therapy, yielding durable responses across various malignancies. However, the clinical benefits of ICIs in GC have been modest, underscoring the need for a comprehensive understanding of immune cell functions within the GC tumor microenvironment (TME). Regulatory T cells (Tregs), a subset of T lymphocytes, play a pivotal role in GC development and progression and serve as prognostic biomarkers for GC patients. This review aims to elucidate the multifaceted roles of Tregs in the pathogenesis, progression, and prognosis of gastric cancer, and establish their actual and future potential as therapeutic targets. By providing insights into the intricate interplay between Tregs and the TME, this review strives to stimulate further investigation and facilitate the development of targeted Treg-based therapeutic strategies for GC.

C-reactive protein kinetics as a predictive marker for long-term outcome of immune checkpoint inhibitors in oesophagogastric cancer

BACKGROUND

The treatment efficacy of immune checkpoint inhibitors (ICIs) is limited, and biomarkers that identify responders are urgently needed. We investigated whether C-reactive protein (CRP) kinetics are associated with the treatment efficacy of ICIs and prognosis in oesophagogastric cancers.

METHODS

We analysed 76 gastric cancer patients treated with nivolumab monotherapy. Patients were classified as CRP-spike, CRP-flat or CRP-increase according to CRP kinetics within 6 weeks after nivolumab initiation, and the treatment response and prognosis were compared. We further validated this classification in 71 oesophageal cancer patients with nivolumab monotherapy.

RESULTS

In the gastric cancer cohort, the CRP-spike, CRP-flat, and CRP-increase subgroups included 9, 37 and 30 patients, respectively. The CRP-spike subgroup had higher disease control rates than the CRP-increase subgroup (P = 0.0068) and had significantly better progression-free survival (PFS) (vs. CRP-flat: P = 0.045, CRP-increase: P = 0.0001). Multivariate analysis for PFS identified CRP-spike (HR = 0.38, P = 0.029) as an independent favourable prognostic factor. In the oesophageal cancer cohort, the CRP-spike, CRP-flat, and CRP-increase subgroups included 13, 27 and 31 patients, respectively, and multivariate analysis for PFS also identified CRP-spike (HR = 0.28, P = 0.0044) as an independent favourable prognostic factor.

CONCLUSIONS

CRP kinetics may be useful in predicting the long-term outcome of nivolumab treatment in oesophagogastric cancers.