The tight junction protein claudin 6 is a potential target for patient-individualized treatment in esophageal and gastric adenocarcinoma and is associated with poor prognosis

CAR T cell therapies in gastrointestinal cancers: current clinical trials and strategies to overcome challenges

Despite multimodal treatment options, most gastrointestinal cancers are still associated with high mortality rates and poor responsiveness to immunotherapy. The unprecedented efficacy of chimeric antigen receptor (CAR)-engineered T cells in the treatment of haematological malignancies raised interest in translating CAR T cell therapies to the treatment of gastrointestinal cancers. Treatment of solid cancers with canonical CAR T cells faces substantial challenges, including the dense architecture of the tumour tissue, the tolerogenic environment with low tumour-intrinsic immunogenicity, the rareness of targetable tumour-selective antigens, the antigenic heterogeneity of cancer cells, and the profound metabolic and immune cell disbalances. This Review provides an overview of CAR T cell trials in the treatment of gastrointestinal cancers, discussing considerations relating to safety, efficacy, potential reasons for failure and options for improving CAR T cells for the future. In addition, lessons regarding how to improve efficacy are drawn from CAR T cells armed with adjuvants that sustain their activation within the hostile environment and activate resident immune cells. As the field is rapidly evolving, current treatment modalities and editing CAR T cell functionalities are being refined towards a potentially more successful CAR T cell therapy for gastrointestinal cancers.

HER2-positive gastric cancer: from targeted therapy to CAR-T cell therapy

Gastric cancer (GC) ranks as the fifth most prevalent cancer on a global scale, with HER2-positive GC representing a distinct subtype that exhibits more intricate biological characteristics. Conventional chemotherapy typically exhibits restricted efficacy in the management of HER2-positive GC. In light of the incessant advancement in molecular targeted therapies, targeting HER2 has emerged as a promising therapeutic approach for this subtype. The advent of antibody-drug conjugates (ADCs) and chimeric antigen receptor T-cell therapy (CAR-T) has furnished novel treatment alternatives for HER2-positive GC. Nevertheless, owing to the pronounced heterogeneity of GC and the complex tumor microenvironment, drug resistance frequently emerges, thereby substantially influencing the effectiveness of HER2-targeted therapy. This article comprehensively summarizes and deliberates upon the strategies of HER2-targeted therapy as well as the underlying resistance mechanisms.

177Lu-Labeled Anticlaudin 6 Monoclonal Antibody for Targeted Therapy in Esophageal Cancer

Advanced or metastatic esophageal cancer (EC) is associated with poor prognosis, necessitating new and effective treatment methods. We assess whether claudin 6 (CLDN6) is a useful target for the imaging and radiopharmaceutical therapy of EC using a novel pair of radioactive nuclides, 89Zr and 177Lu. Methods: CLDN6 messenger RNA expression was evaluated in 2 EC datasets (n = 436) and through a retrospective analysis of 109 patients with EC. We then used an anti-CLDN6 monoclonal antibody (IMAB027) labeled with 89Zr and 177Lu ([89Zr]Zr-DFO-IMAB027 and [177Lu]Lu-DOTA-IMAB027) for PET imaging and therapy, respectively. Imaging and biodistribution analyses were performed using the TE-1-CLDN6 xenograft model. Finally, the therapeutic potential of [177Lu]Lu-DOTA-IMAB027 was evaluated in both the TE-1-CLDN6 and the CLDN6-PDX (patient-derived xenograft) models. Results: CLDN6 messenger RNA expression was elevated in EC compared with healthy esophageal tissues. The CLDN6 expression rate was 0 in healthy esophageal tissue but was 79.8% in EC tissue. The [89Zr]Zr-DFO-IMAB027 showed the ability to effectively image EC xenografts with high CLDN6 expression. In the TE-1-CLDN6 model, there was a significant difference in tumor volume between the 11.1-MBq [177Lu]Lu-DOTA-IMAB027 treatment group and the control group (P < 0.001). The tumor growth inhibition rate in the 11.1-MBq [177Lu]Lu-DOTA-IMAB027 group was 101.74%. In the PDX model, significant differences in tumor volume were observed among all [177Lu]Lu-DOTA-IMAB027 treatment groups and the control group (P < 0.05). Specifically, the tumor growth inhibition rate of the 11.1-MBq [177Lu]Lu-DOTA-IMAB027 group was 79.04%, whereas that of the 3.7-MBq group was 77.20%. However, the difference in efficacy between the high-dose and low-dose groups was not statistically significant (P > 0.05). Conclusion: The differential expression of CLDN6 between tumors and the normal esophagus shows its potential as a diagnostic and therapeutic target for EC. The radiotracer [89Zr]Zr-DFO-IMAB027 showed high contrast when visualizing CLDN6-expressing xenografts for PET imaging, and [177Lu]Lu-DOTA-IMAB027 induced rapid tumor regression in both the TE-1-CLDN6 and the CLDN6-PDX models. This research has implications for improving the radioligand diagnosis and treatment of EC.

High expression of H2AX/γ-H2AX is associated with distinct biological pathway alterations and shorter survival in oropharyngeal squamous cell carcinoma

BACKGROUND

The histone gene H2AX and its phosphorylated protein γ-H2AX play a crucial role in the DNA damage response. This study investigates the expression of H2AX mRNA and its phosphorylated γ-H2AX protein in oropharyngeal squamous cell carcinoma (OPSCC), its association with distinct biological pathway alterations and its potential as a biomarker.

MATERIALS AND METHODS

Expression of H2AX mRNA in 76 OPSCC from The Cancer Genome Atlas (TCGA) cohort was analyzed. Patients were stratified into H2AXhigh- and H2AXlow OPSCC based on a survival-associated cutoff. Differentially expressed genes were identified using DESeq2, followed by pathway enrichment analyses. Immunohistochemical staining of γ-H2AX protein expression was performed on an independent cohort of 209 OPSCC, followed by survival and Cox regression analyses.

RESULTS

High H2AX mRNA expression was a significant prognostic factor associated with shorter OS in the TCGA OPSCC cohort (HR 4.77, p = 0.04). In H2AXhigh tumors, differential gene expression analysis revealed upregulation of genes regulating DNA repair and cell cycle (CDK1, CCNB1, ZWINT). High γ-H2AX protein expression was significantly associated with HPV-negative OPSCC (p = 0.005), and remained an independent predictor of poor survival in the total OPSCC cohort (HR 2.24, p = 0.03) and particularly in HPV-negative patients (HR 3.67, p = 0.007).

CONCLUSION

H2AX/γ-H2AX expression is a potential prognostic biomarker in OPSCC, with elevated levels indicating poor survival, especially in HPV-negative cases. These findings suggest distinct molecular behaviors in OPSCC based on H2AX expression and highlight the need for further investigation into its therapeutic implications.

m6A-Methylated NUTM2B-AS1 Promotes Hepatocellular Carcinoma Stemness Feature via Epigenetically Activating BMPR1A Transcription

Purpose

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies in the world. Oncofetal proteins are the optimal diagnostic biomarkers and therapeutic targets for HCC. As the most abundant modification in RNA, N6-methyladenosine (m6A) has been reported to be involved in HCC initiation and progression. However, whether m6A has oncofetal characteristics remains unknown.

Methods

Gene expression in HCC tissues and cells was detected using qPCR. The level of m6A methylation was determined using methylated RNA immunoprecipitation assay. The biological roles of NUTM2B-AS1 in HCC were detected using Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine incorporation, and spheroid formation assays. The mechanisms underlying the roles of NUTM2B-AS1 were explored using RNA immunoprecipitation (RIP), chromatin isolation by RNA purification (ChIRP), chromatin immunoprecipitation (ChIP), and assay for transposase-accessible chromatin (ATAC).

Results

NUTM2B-AS1 was identified as a novel oncofetal long noncoding RNA that was upregulated in the fetal liver and HCC and silenced in adult liver tissues. METTL3 and METTL16 induce m6A hypermethylation of NUTM2B-AS1. The m6A methylation levels of NUTM2B-AS1 exhibit oncofetal characteristics. m6A methylation upregulates NUTM2B-AS1 expression by increasing NUTM2B-AS1 transcript stability. m6A-methylated NUTM2B-AS1 promotes HCC cell proliferation and stemness via epigenetically activating BMPR1A expression. NUTM2B-AS1 specifically binds to BMPR1A promoter. m6A-methylated NUTM2B-AS1 is recognized by the m6A reader YTHDC2, which further binds to the H3K4 methyltransferase MLL1. m6A-methylated NUTM2B-AS1 recruits YTHDC2 and MLL1 to BMPR1A promoter, leading to increased H3K4me3 and chromatin accessibility at BMPR1A promoter. Functional rescue assays suggest that BMPR1A is a critical mediator of the oncogenic role of m6A-methylated NUTM2B-AS1 in HCC.

Conclusion

METTL3- and METTL16-mediated m6A methylation of NUTM2B-AS1 is a novel oncofetal molecular event in HCC that promotes HCC stemness via epigenetically activating BMPR1A transcription.

Optimizing CAR-T cell therapy for solid tumors: current challenges and potential strategies

Chimeric antigen receptor (CAR)-T cell therapy demonstrates substantial efficacy in various hematological malignancies. However, its application in solid tumors is still limited. Clinical studies report suboptimal outcomes such as reduced cytotoxicity of CAR-T cells and tumor evasion, underscoring the need to address the challenges of sliding cytotoxicity in CAR-T cells. Despite improvements from fourth and next-generation CAR-T cells, new challenges include systemic toxicity from continuously secreted proteins, low productivity, and elevated costs. Recent research targets genetic modifications to boost killing potential, metabolic interventions to hinder tumor progression, and diverse combination strategies to enhance CAR-T cell therapy. Efforts to reduce the duration and cost of CAR-T cell therapy include developing allogenic and in-vivo approaches, promising significant future advancements. Concurrently, innovative technologies and platforms enhance the potential of CAR-T cell therapy to overcome limitations in treating solid tumors. This review explores strategies to optimize CAR-T cell therapies for solid tumors, focusing on enhancing cytotoxicity and overcoming application restrictions. We summarize recent advances in T cell subset selection, CAR-T structural modifications, infiltration enhancement, genetic and metabolic interventions, production optimization, and the integration of novel technologies, presenting therapeutic approaches that could improve CAR-T cell therapy's efficacy and applicability in solid tumors.

Claudins: from gatekeepers of epithelial integrity to potential targets in hepato-pancreato-biliary cancers

Claudins, a family of tetraspan transmembrane proteins, are critical to the integrity of tight junctions in epithelia and endothelia, influencing cellular processes such as development, differentiation, and apoptosis. Abnormal claudin expression is associated with various malignancies, particularly affecting tissue architecture and potentially facilitating tumor invasion and metastasis. In this comprehensive review, we explore the multifaceted functions of claudins: their expression, specific roles in cancer with a focus on hepato-pancreato-biliary malignancies and highlight their potential as therapeutic targets. We discuss current claudin-targeted therapies, including monoclonal antibodies, antibody-drug conjugates, bispecific T-cell engager and chimeric antigen receptor T-cell therapies. These approaches show promise in pre-clinical and clinical studies, particularly in hepato-pancreato-biliary cancers with large unmet needs. Despite these early signs of efficacy, challenges remain in effectively targeting these proteins due to their structural resemblance and overlapping functions.

Updates in Translational Science for Esophageal and Gastric Cancers

In this article, the authors summarize the current state of translational science for esophageal and gastric cancers. The available targeted therapies, immunotherapies, and recently discovered molecular targets are reviewed. The authors introduce circulating tumor deoxyribonucleic acid and its promise as a biomarker to detect disease recurrence. The authors present patient-derived organoids as a new model for studying carcinogenesis and treatment responses. Finally, we discuss the implications of organoid models for precision oncology and describe exciting new work applying gene editing technology to organoids and studying tumor-microenvironment interactions using 3-dimensional co-culture systems.

Fetal gut cell-like differentiation in esophageal adenocarcinoma defines a rare tumor subtype with therapeutically relevant claudin-6 positivity and SWI/SNF gene alteration

Esophageal adenocarcinoma (EAC) is one of the deadliest tumor entities worldwide, with a 5-year survival rate of less than 25%. Unlike other tumor entities, personalized therapy options are rare, partly due to the lack of knowledge about specific subgroups. In this publication, we demonstrate a subgroup of patients with EAC in a large screening cohort of 826 patients, characterized by specific morphological and immunohistochemical features. This subgroup represents approximately 0.7% (6/826) of the total cohort. Morphological features of this subgroup show a striking clear cytoplasm of the tumour cells and the parallel existence of rare growth patterns like yolk sac-like differentiation and enteroblastic differentiation. Immunohistochemistry reveals expression of the fetal gut cell-like proteins Sal-like protein 4 (SALL4), claudin-6, and glypican 3. Interestingly, we find a correlation with alterations of SWI/SNF-complex associated genes, which are supposed to serve as tumor suppressor genes in various tumour entities. Our results suggest a possible implication of rare tumour subtypes in the WHO classification for EACs according to the classification for gastric cancer. Furthermore, claudin-6 positive tumors have shown promising efficacy of CAR T cell therapy in the recently published BNT-211-01 trial (NCT04503278). This represents a personalized therapeutic option for this tumor subtype.

Preclinical efficacy and pharmacokinetics of an RNA-encoded T cell-engaging bispecific antibody targeting human claudin 6

We present the preclinical pharmacology of BNT142, a lipid nanoparticle (LNP)-formulated RNA (RNA-LNP) encoding a T cell-engaging bispecific antibody that monovalently binds the T cell marker CD3 and bivalently binds claudin 6 (CLDN6), an oncofetal antigen that is absent from normal adult tissue but expressed on various solid tumors. Upon BNT142 RNA-LNP delivery in cell culture, mice, and cynomolgus monkeys, RNA is translated, followed by self-assembly into and secretion of the functional bispecific antibody RiboMab02.1. In vitro, RiboMab02.1 mediated CLDN6 target cell-specific activation and proliferation of T cells, and potent target cell killing. In mice and cynomolgus monkeys, intravenously administered BNT142 RNA-LNP maintained therapeutic serum concentrations of the encoded antibody. Concentrations of RNA-encoded RiboMab02.1 were maintained longer in circulation in mice than concentrations of directly injected, sequence-identical protein. Weekly injections of mice with BNT142 RNA-LNP in the 0.1- to 1-μg dose range were sufficient to eliminate CLDN6-positive subcutaneous human xenograft tumors and increase survival over controls. Tumor regression was associated with an influx of T cells and depletion of CLDN6-positive cells. BNT142 induced only transient and low cytokine production in CLDN6-positive tumor-bearing mice humanized with peripheral blood mononuclear cells (PBMCs). No signs of adverse effects from BNT142 RNA-LNP administration were observed in mice or cynomolgus monkeys. On the basis of these and other findings, a phase 1/2 first-in-human clinical trial has been initiated to assess the safety and preliminary efficacy of BNT142 RNA-LNP in patients with CLDN6-positive advanced solid tumors (NCT05262530).

HER2+ advanced gastric cancer: Current state and opportunities (Review)

Human epidermal growth factor receptor 2 (HER2)+ gastric cancer (GC) is a distinct subtype of GC, accounting for 10‑20% of all cases of GC. Although the development of the anti‑HER2 monoclonal antibody trastuzumab has markedly improved response rates and prognosis of patients with HER2+ advanced GC (AGC), drug resistance remains a considerable challenge. Therefore, dynamic monitoring of HER2 expression levels can facilitate the identification of patients who may benefit from targeted therapy. Besides trastuzumab, DS‑8201 and RC48 have been applied in the treatment of HER2+ AGC, and several novel anti‑HER2 therapies are undergoing preclinical/clinical trials. At present, combination immunotherapy with anti‑HER2 agents is used as the first‑line treatment of this disease subtype. New promising approaches such as chimeric antigen receptor T‑cell immunotherapy and cancer vaccines are also being investigated for their potential to improve clinical outcomes. The current review provides new insights that will guide the future application of anti‑HER2 therapy by summarizing research progress on targeted therapy drugs for HER2+ AGC and combination treatments.