Claudin 18.2 expression in digestive neuroendocrine neoplasms: a clinicopathological study

BACKGROUND

Claudin 18.2-targeted therapy has shown significant efficacy in treating claudin 18.2-positive cancers. However, limited systematic studies have investigated characteristics of claudin 18.2 expression in neuroendocrine neoplasms (NENs).

METHODS

Data and specimens from 403 cases of digestive NENs were retrospectively collected, and claudin 18.2 expression was detected using immunochemical staining.

RESULTS

Claudin 18.2 was positive in 19.6% (79/403) of the digestive NENs. The highest positive rate of claudin 18.2 was observed in gastric NENs (72/259, 27.8%), accounting for 91.1% (72/79) of all positive cases. The positivity rate was significantly higher in gastric NENs compared to pancreatic (2/78, 2.6%) or colorectal NENs (2/38, 5.3%; p < 0.05). For digestive NENs, claudin 18.2 positivity was significantly higher in neuroendocrine carcinomas (NECs) (37/144, 25.7%) than in neuroendocrine tumours (NETs; 14/160, 8.8%; p < 0.001), but no significant difference was found between gastric NECs (59/213, 27.7%) and gastric NETs (13/46, 28.3%; p > 0.05). The positivity was significantly higher in large-cell NECs (LCNECs; 28/79, 35.4%) and MiNEN (mixed neuroendocrine-non- neuroendocrine neoplasms)-LCNECs (23/66, 34.8%) compared to small-cell NECs (SCNECs; 9/65, 13.8%) and MiNEN-SCNECs (5/33, 15.2%; p < 0.05). Claudin 18.2 expression was more prevalent in gastric NENs than in pancreatic (12.5 ×; p = 0.001) and colorectal NENs (5.9 ×; p = 0.021). Claudin 18.2 staining was a useful method for identify the gastric origins of NETs, with a sensitivity of 28.3% and a specificity of 99.1%.

CONCLUSION

The expression characteristics of claudin 18.2 in NENs were characterized, which may provide a clinicopathological reference for targeted therapies in patients with NENs.

DR30318, a novel tri-specific T cell engager for Claudin 18.2 positive cancers immunotherapy

BACKGROUND

Claudin 18.2 (CLDN18.2) is a highly anticipated target for solid tumor therapy, especially in advanced gastric carcinoma and pancreatic carcinoma. The T cell engager targeting CLDN18.2 represents a compelling strategy for enhancing anti-cancer efficacy.

METHODS

Based on the in-house screened anti-CLDN18.2 VHH, we have developed a novel tri-specific T cell engager targeting CLDN18.2 for gastric and pancreatic cancer immunotherapy. This tri-specific antibody was designed with binding to CLDN18.2, human serum albumin (HSA) and CD3 on T cells.

RESULTS

The DR30318 demonstrated binding affinity to CLDN18.2, HSA and CD3, and exhibited T cell-dependent cellular cytotoxicity (TDCC) activity in vitro. Pharmacokinetic analysis revealed a half-life of 22.2-28.6 h in rodents and 41.8 h in cynomolgus monkeys, respectively. The administration of DR30318 resulted in a slight increase in the levels of IL-6 and C-reactive protein (CRP) in cynomolgus monkeys. Furthermore, after incubation with human PBMCs and CLDN18.2 expressing cells, DR30318 induced TDCC activity and the production of interleukin-6 (IL-6) and interferon-gamma (IFN-γ). Notably, DR30318 demonstrated significant tumor suppression effects on gastric cancer xenograft models NUGC4/hCLDN18.2 and pancreatic cancer xenograft model BxPC3/hCLDN18.2 without affecting the body weight of mice.

Claudin-18.2 testing and its impact in the therapeutic management of patients with gastric and gastroesophageal adenocarcinomas: A literature review with expert opinion

Claudin-18.2 (CLDN18.2) is a member of the tight junction protein family and is a highly selective biomarker with frequent abnormal expression during the occurrence and development of various primary malignant tumors, including gastric cancer (GC) and esophago-gastric junction adenocarcinomas (EGJA). For these reasons, CLDN18.2 has been investigated as a therapeutic target for GC/EGJA malignancies. Recently, zolbetuximab has been proposed as a new standard of care for patients with CLDN18.2-positive, HER2-negative, locally advanced and metastatic GC/EGJA. The use of CLDN18 IHC assays to select patients who might benefit from anti-CLDN18.2 therapy is currently entering clinical practice. In this setting, pathologists play a central role in therapeutic decision-making. Accurate biomarker assessment is essential to ensure the best therapeutic option for patients. In the present review, we provide a comprehensive overview of available evidence on CLDN18.2 testing and its impact on the therapeutic management of patients with GC/EGJA, as well as some practical suggestions for CLDN18.2 staining interpretation and potential pitfalls in the real-world setting.

Current and Future Biomarkers in Esophagogastric Adenocarcinoma

PURPOSE

Biomarker-based therapies have shown improved patient outcomes across various cancer types. The purpose of this review to summarize our knowledge of current and future biomarkers in esophagogastric adenocarcinoma (EGA).

METHODS

In this publication, we will review current standard biomarkers in patients with upper GI cancers. We will also discuss novel biomarkers that are under investigations and their associated therapies that are currently in clinical trials.

RESULTS

EGAa are a group of heterogeneous diseases, both anatomically and molecularly. There are several established biomarkers (HER2, PD-L1, microsattelite instability or mismatch repair protein expression) that allow for individualized treatments for patients with these cancers. There are also several emerging biomarkers for EGA, some of which have clinically relevant associated therapies. Claudin 18.2 is the furthest along among these. Anti-claudin antibody, zolbetuximab, improved overall survival in biomarker select patients with advanced GEA in two phase 3 studies. Other novel biomarkers, such as FGFR2b and DKN01, are also in the process of validation, and treatments based on the presence of these biomarkers are currently in clinical studies.

CONCLUSION

Ongoing efforts to identify novel biomarkers in EGA have led to enhanced subclassification of upper GI cancers. These advances, coupled with the strategic application of targeted therapies and immunotherapy when appropriate, hold promise to further improve patients outcomes.

Treatment of gastric adenocarcinoma: A rapidly evolving landscape

Gastric adenocarcinoma (GC) and gastroesophageal junction adenocarcinoma represent frequent and severe diseases whose management has radically changed over the last 10 years. With the advent of second- and third-line standard therapies for metastatic GC patients in the 2010s, the molecular dismemberment of the disease and positive trials with immunotherapy and targeted agents will mark the 2020s. New treatment options have emerged in the neoadjuvant, adjuvant, and metastatic setting. In addition to improved multimodal treatment in operable patients, new subgroups have emerged depending on molecular alterations (HER2, Microsatellite instability) or expression of specific proteins in the tumour (PDL1, Claudin 18.2) making immunohistochemistry central in profiling the tumour for an optimal individualised management. The aim of this review is to describe the current standards of management of early and late stage GC and the molecular markers needed today to optimally manage our patients together with future perspectives on this disease.

Current and Emerging Role of Monoclonal Antibody-Based First-Line Treatment in Advanced Gastro-Esophageal and Gastric Cancer

Gastric cancer is the fifth most common malignancy worldwide and one of the main causes of cancer-related death. While surgical treatment is the only curative option for early disease, many have inoperable or advanced disease at diagnosis. Treatment in this case would be a combination of chemotherapy and immunotherapy. Gastro-esophageal (GEJ) and gastric cancer (GC) genetic profiling with current molecular diagnostic techniques has significantly changed the therapeutic landscape in advanced cancers. The identification of key players in GEJ and GC survival and proliferation, such as human epidermal growth factor 2 (HER2), vascular endothelial growth factor (VEGF), and programmed cell death protein 1 (PD-1)/programmed cell death ligand-1 (PD-L1), has allowed for the individualization of advanced cancer treatment and significant improvement in overall survival and progression-free survival of patients. This review comprehensively examines the current and emerging role of monoclonal antibody-based first-line treatments in advanced GEJ and GC. We explore the impact of monoclonal antibodies targeting HER2, VEGF, PD-1/PD-L1, and Claudin 18.2 (CLDN18.2) on the first-line treatment landscape by talking about key clinical trials. This review emphasizes the importance of biomarker testing for optimal treatment selection and provides practical recommendations based on ASCO guidelines.

CLDN18.2 expression and its impact on prognosis and the immune microenvironment in gastric cancer

BACKGROUND

The investigational use of zolbetuximab (IMAB362), a groundbreaking monoclonal antibody medication targeting claudin 18.2 (CLDN18.2), for treatment of advanced gastrointestinal cancers is currently underway. The unclear clinicopathological characteristics and tumour immune microenvironment of CLDN18.2-positive gastric cancer (GC) make it difficult to develop and optimize CLDN18.2-targeted therapies.

METHODS

A total of 451 tumour tissues, 342 matched paraneoplastic tissues, and 107 matched metastatic lymph nodes were collected from GC patients. These specimens were stained for CLDN18.2 expression and quantified using immunohistochemistry (IHC). Correlations between CLDN18.2 expression and clinicopathological features as well as immune-related factors were analysed. Survival curves were drawn using the Kaplan‒Meier approach, and independent factors affecting GC prognosis were identified using Cox regression analysis. Information from relevant databases was used for corroboration.

RESULTS

Expression of the CLDN18.2 gene was significantly lower in gastric tumour tissues than in normal tissues (p < 0.001) but comparable in metastatic lymph nodes (p = 0.851). CLDN18.2 expression was significantly associated with Borrmann type, degree of differentiation, PD-L1 expression, and survival in GC patients and was identified as an independent risk factor for patient prognosis (HR = 1.57, 95% CI 1.16-2.11, p = 0.003). There was no correlation between CLDN18.2 expression and HER2, Lauren type, tumour size, TNM stage, or any other clinicopathological characteristic. In CLDN18.2-positive tumours, fractions of CD4 + T cells and CD8 + T cells were significantly higher than those in CLDN18.2-negative tumours. Patients with CLDN18.2-negative expression and significant CD4 + T-cell or CD8 + T-cell infiltration had the best prognosis (5-year OS: 61.0%, P = 0.036; 5-year OS: 62.2%, P = 0.034).

CONCLUSIONS

CLDN18.2 is expressed at a low level in tumour tissues and serves as an independent prognostic factor for patients with GC. Furthermore, CLDN18.2 correlates with immune infiltrating cells and PD-L1 expression.

Jianpi Yangzheng decoction suppresses gastric cancer progression via modulating the miR-448/CLDN18.2 mediated YAP/TAZ signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Developing complementary and effective drugs with less toxicity is urgent for gastric cancer (GC) therapy. Jianpi Yangzheng Decoction (JPYZ) is a curative medical plants formula against GC in clinic while its molecular mechanism remains to be further elucidated.

AIM OF THE STUDY

To evaluate the in vitro and in vivo anticancer efficacy of JPYZ against GC and its potential mechanisms.

MATERIALS AND METHODS

The effect of JPYZ on regulating the candidate targets were screened and examined by RNA-Seq, qRT-PCR, luciferase reporter assay, and immunoblotting. Rescue experiment was conducted to authenticate the regulation of JPYZ on the target gene. Molecular interaction, intracellular localization and function of target genes were elucidated via Co-IP and cytoplasmic-nuclear fractionation. The impact of JPYZ on the abundance of target gene in clinical specimens of GC patients was evaluated by IHC.

RESULTS

JPYZ treatment suppressed the proliferation and metastasis of GC cells. RNA seq revealed JPYZ significantly downregulated miR-448. A reporter plasmid containing CLDN18 3'-UTR WT exhibited significant decrease in luciferase activity when co-transfected with miR-448 mimic in GC cells. CLDN18.2 deficiency promoted the proliferation and metastasis of GC cells in vitro, as well as intensified the growth of GC xenograft in mice. JPYZ reduced the proliferation and metastasis of GC cells with CLDN18.2 abrogation. Mechanically, suppressed activities of transcriptional coactivator YAP/TAZ and its downstream targets were observed in GC cells with CLDN18.2 overexpression and those under JPYZ treatment, leading to cytoplasmic retention of phosphorylated YAP at site Ser-127. High abundance of CLDN18.2 was detected in more GC patients who received chemotherapy combined with JPYZ.

CONCLUSION

JPYZ has an inhibitory effect on GC growth and metastasis partly by elevating CLDN18.2 abundance in GC cells, indicating more patients may benefit from combination therapy of JPYZ and the upcoming CLDN18.2 target agents.

Prognostic value of claudin 18.2 expression in gastric adenocarcinoma

BACKGROUND

Claudin 18.2 (CLDN18.2) is a cell surface protein expressed by gastric cancer cells. The monoclonal antibody zolbetuximab binds CLDN18.2-positive cancer cells and causes cancer cell death. A few studies researched the prognostic effect of CLDN18.2 expression in metastatic gastric adenocarcinoma.

AIM

To identify the prognostic value of CLDN18.2 expression in patients with metastatic gastric adenocarcinoma.

METHODS

This study was conducted with 65 patients over the age of 18 who were diagnosed with metastatic gastric adenocarcinoma. We investigated the effect of CLDN18.2 expression on clinicopathological characteristics (age, sex, histological grade, Lauren classification, family history, metastatic site, HER2 expression) and prognosis for patients with metastatic gastric adenocarcinoma.

RESULTS

CLDN18.2 expression was positive in 73.8% (48) of the patients. During the median 17.7-mo follow-up period, 89.2% (58) of the patients died. Median progression-free survival and overall survival (OS) were 6 mo (95% confidence interval: 1.6-10.4) and 12 mo (95% confidence interval: 7.5-16.5). There was no statistically significant correlation between CLDN18.2 expression and clinicopathological characteristics of the patients. In univariate and multivariate Cox regression analysis, there was no correlation between clinicopathological characteristics of patients and progression-free survival or OS.

CONCLUSION

CLDN18.2 expression was quite high in patients with gastric adenocarcinoma, identifying the proportion of the patients in whom zolbetuximab would be efficacious. There is no statistically significant correlation with clinicopathological characteristics and OS. CLDN18.2 is not a prognostic marker in patients with gastric adenocarcinoma, although it is predictive.

Immunological effects and activity of multiple doses of zolbetuximab in combination with zoledronic acid and interleukin-2 in a phase 1 study in patients with advanced gastric and gastroesophageal junction cancer

PURPOSE

Zolbetuximab (IMAB362) is engineered to induce antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity. We evaluated ADCC activity and the impact of the immune-modulating drugs zoledronic acid (ZA) and interleukin-2 (IL-2) as co-treatment with zolbetuximab on relevant immune cell populations and ADCC lysis activity.

METHODS

This phase 1, multicenter, open-label study investigated the immunological effects and activity, safety, tolerability, and antitumor activity of multiple doses of zolbetuximab alone (n = 5) or in combination with ZA (n = 7) or with ZA plus two different dose levels of IL-2 (low dose: 1 million international units [mIU] [n = 9]; intermediate dose: 3 mIU [n = 7]) in pretreated patients with advanced gastric and gastroesophageal junction (G/GEJ) adenocarcinoma.

RESULTS

Twenty-eight patients with previously treated advanced G/GEJ adenocarcinoma that was CLDN18.2-expressing were enrolled into four treatment arms. Treatment with zolbetuximab + ZA + IL-2 induced short-lived expansion and activation of ADCC-mediating cell populations, namely γ9δ2 T cells and natural killer cells, within 2 days after administration; this effect was more pronounced with intermediate-dose IL-2. Expansion and activation of regulatory T cells treated with either IL2 dose was moderate and short-lived. Strong ADCC activity was observed with zolbetuximab alone. Short-lived ADCC activity was observed in several patients treated with ZA + intermediate-dose IL-2, but not lower-dose IL-2. In the clinical efficacy population, the best confirmed response was stable disease (n = 11/19; 58%).

CONCLUSIONS

Zolbetuximab mediates proficient ADCC in patients with pretreated advanced G/GEJ cancers. Co-treatment with ZA + IL-2 did not further improve this effect.

TRIAL REGISTRATION

NCT01671774.

Emerging targets in gastroesophageal adenocarcinoma: what the future looks like

Gastroesophageal adenocarcinoma (GEA) is a heterogeneous disease with a poor prognosis. Chemotherapy has been the cornerstone in treating metastatic diseases. Recently, the introduction of immunotherapy demonstrated improved survival outcomes in localized and metastatic diseases. Beyond immunotherapy, several attempts were made to improve patient survival by understanding the molecular mechanisms of GEA and several molecular classifications were published. In this narrative review, we will discuss emerging targets in GEA, including fibroblast growth factor receptor and Claudin 18.2, as well as the accompanying drugs. In addition, novel agents directed against well-known targets, such as HER2 and angiogenesis, will be discussed, as well as cellular therapies like CAR-T and SPEAR-T cells.

Development and comparison of (68)Ga/(18)F/(64)Cu-labeled nanobody tracers probing Claudin18.2

Claudin 18.2 (CLDN18.2) is an emerging target for the treatment of gastric cancers. We aim to develop tracers to image the expression of CLDN18.2. A humanized nanobody targeting CLDN18.2 (clone hu19V3) was produced and labeled with ⁶⁸Ga, ⁶⁴Cu, and ¹⁸F. The tracers were investigated in subcutaneous and metastatic models established using two different mouse types (nude and Balb/c mice) and two different cell lines (CHO-CLDN18.2 and CT26-CLDN18.2). Gastric cancer patient-derived xenograft (PDX) models were further established for validation experiments. Three novel CLDN18.2-targeted tracers (i.e., [⁶⁸Ga]Ga-NOTA-hu19V3, [⁶⁴Cu]Cu-NOTA-hu19V3, and [¹⁸F]F-hu19V3) were developed with good radiochemical yields and excellent radiochemical purities. [⁶⁸Ga]Ga-NOTA-hu19V3 immuno-positron emission tomography (immunoPET) rapidly delineated subcutaneous CHO-CLDN18.2 lesions and CT26-CLDN18.2 tumors, as well as showing excellent diagnostic value in PDX models naturally expressing CLDN18.2. While [⁶⁸Ga]Ga-NOTA-hu19V3 had high kidney accumulation, [⁶⁴Cu]Cu-NOTA-hu19V3 showed reduced kidney accumulation and improved image contrast at late time points. Moreover, [¹⁸F]F-hu19V3 was developed via click chemistry reaction under mild conditions and precisely disseminated CHO-CLDN18.2 lesions in the lungs. Furthermore, region of interest analysis, biodistribution study, and histopathological staining results correlated well with the in vivo imaging results. Taken together, immunoPET imaging with the three tracers can reliably visualize CLDN18.2 expression.

Prognostic impact of Claudin 18.2 in gastric and esophageal adenocarcinomas

Introduction

The tight junction molecule Claudin 18.2 is selectively expressed in healthy and malignant gastric epithelial tissue and is a promising therapy target for high Claudin 18.2 expressing adenocarcinomas of the esophagogastric junction and stomach (AEG/S).

Methods

This study analyzed the prevalence, characteristics and prognostic impact of Claudin 18.2 expression in primary tumor, lymph node and distant metastasis in a large Caucasian AGE/S cohort with 414 patients.

Results

Claudin 18.2 was highly expressed in 17.1% of primary tumors, 26.7% of lymph node metastasis and 16.7% of distant metastasis. High Claudin 18.2 expression in lymph node metastasis and primary tumors correlated significantly (p < 0.001). High expression of Claudin 18.2 was neither associated with histomorphogical subtype, or tumor state, nor with overall survival.

Conclusion

In Caucasian AEG/S patients, 17.1% appeared to be eligible for an anti-Claudin 18.2 therapy. Claudin 18.2 expression itself has no impact on prognosis and is not related to any tumor subtype.

Electronic supplementary material

The online version of this article (10.1007/s12094-020-02380-0) contains supplementary material, which is available to authorized users.

Evaluation and reflection on claudin 18.2 targeting therapy in advanced gastric cancer

Claudin 18.2 (CLDN18.2) is a tight-junction protein. CLDN18.2-targeting strategy has cut a striking figure in CLDN18.2 positive patients with advanced gastric cancer. Zolbetuximab, the CLDN18.2 antibody, obtained a better clinical benefit in patients compared with the controlled. In phase II trials, combination treatment of epirubicin, oxaliplatin and capecitabine (EOX) + zolbetuximab achieved the optimal effects of overall survival which extended to 13.2 months with tolerable safety events, indicating its greater potential playing the second promising target in gastric cancer. This review will reveal the definitive clinical benefit CLDN18.2-targeting therapies have achieved and update the highlighting development (like chimeric antigen receptor T-cell immunotherapy) to CLDN18.2 positive patients. We then focus on 10 questions arisen from recent progress and anticipate to provide a future perspective for novel cancer treatment.

Next-generation sequencing and biomarkers for gastric cancer: what is the future?

Recent years have witnessed an improved understanding of tumour biology and the molecular features of gastric cancer. Remarkable advances in next-generation sequencing technologies have defined the genomic landscape of gastric cancer. In fact, several molecular classifications have been proposed, and distinct molecular subtypes have been identified, which could serve as a roadmap for patient stratification and trials of targeted therapies. At present, clinical trials of new agents, such as receptor tyrosine kinases inhibitors, antibody-drug conjugates and IMAB362 (anti-Claudin 18.2), are ongoing. Furthermore, biomarkers of immune checkpoint inhibitors or combination therapy have been ardently investigated. These developments could facilitate precision medicine for gastric cancer in the near future.

Dawn of precision medicine on gastric cancer

BACKGROUND

In recent years, a better understanding of tumor biology and molecular features of gastric cancer has been reached. It may serve as a roadmap for patient stratification and trials of targeted therapies. The apparent efficacy of PD-1 blockade might be limited to a relatively small subset of advanced gastric cancer patients.

MATERIALS AND METHODS

In this study, preclinical and clinical studies, which investigated molecular features, promising treatment targets, and immune checkpoint inhibitor in gastric cancer, were reviewed via PubMed and the congress webpages of the American Society of Clinical Oncology and European Society of Medical Oncology.

RESULTS

Next-generation sequencing technologies have defined the genomic landscape of gastric cancer. Indeed, several molecular classifications have been proposed, and distinct molecular subtypes have been identified. Based on these molecular profiles, clinical trials of new agents such as receptor tyrosine kinases inhibitors, antibody-drug conjugates, and IMAB362 (anti-Claudin 18.2) are ongoing. In addition, biomarkers to predict response during immune checkpoint inhibitors and combination therapy have been enthusiastically investigated.

CONCLUSION

Remarkable advances in an understanding of molecular profiles of gastric cancer enable the development of novel agents. The better treatment selection of immune checkpoint inhibitors or combination therapy should be established. These developments could facilitate precision medicine on gastric cancer in the near future.

Characterization of zolbetuximab in pancreatic cancer models

In healthy tissue, the tight junction protein Claudin 18.2 (CLDN18.2) is present only in the gastric mucosa. Upon malignant transformation of gastric epithelial tissue, perturbations in cell polarity lead to cell surface exposure of CLDN18.2 epitopes. Moreover, CLDN18.2 is aberrantly expressed in malignancies of several other organs, such as pancreatic cancer (PC). A monoclonal antibody, zolbetuximab (formerly known as IMAB362), has been generated against CLDN18.2. In a phase 2 clinical trial (FAST: NCT01630083), zolbetuximab in conjunction with chemotherapy prolonged overall and progression-free survival over chemotherapy alone and improved quality of life. In this study, the mechanism of action and antitumor activity of zolbetuximab were investigated using nonclinical PC models. Zolbetuximab bound specifically and with strong affinity to human PC cells that expressed CLDN18.2 on the cell surface. In ex vivo systems using immune effector cells and serum from healthy donors, zolbetuximab induced antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC), resulting in the lysis of cultured human PC cells. The amplitude of ADCC and CDC directly correlated with cell surface CLDN18.2 levels. The chemotherapeutic agent gemcitabine upregulated CLDN18.2 expression in cultured human PC cells and enhanced zolbetuximab-induced ADCC. In mouse xenograft tumors derived from human PC cell lines, including gemcitabine-refractory ones, zolbetuximab slowed tumor growth, benefited survival, and attenuated metastases development. The results presented here validate CLDN18.2 as a targetable biomarker in PC and support extension of the clinical development of zolbetuximab to patients with CLDN18.2-expressing PC.

New agents on the horizon in gastric cancer

Background

Conventional cytotoxic chemotherapy has been the backbone of advanced gastric cancer treatment for decades and still represents a key element of the therapeutic armamentarium. However, only small increments in survival outcomes have been reached. A better understanding of genetic alterations and molecular signatures of gastric cancer has been reached in the last years. It will serve as a roadmap for better treatment stratification and future drug development.

Materials and methods

We reviewed preclinical and clinical studies that assessed novel treatment targets and emerging drug therapies in gastric cancer. We performed research via PubMed, and the congress webpages of the American Society of Clinical Oncology, European Society of Medical Oncology and the Japanese Society of Medical Oncology.

Results

HER2-targeting with trastuzumab is effective in HER2-positive metastatic gastric cancer; combined HER2 targeting strategies are being investigated. Studies assessing the role of HER2 targeting in the perioperative setting are ongoing. Novel treatment targets include inhibition of cancer stemness-related signaling pathways like STAT3. DNA damage repair and Claudin 18.2, a tight junction protein with high expression in gastric cancers are also novel molecular drug targets. Modification of the tumor microenvironment, including activation of immune response by PD-1/PD-L1 checkpoint inhibitors and stroma modification by matrix metalloproteinase-9 inhibition, led to first promising treatment results.

Conclusion

Novel treatment options for gastric cancer patients are emerging. They involve novel mechanisms of action, and are based on our constantly increasing understanding of tumor biology and better molecular stratification of gastric cancer patients.