Trastuzumab emtansine versus taxane use for previously treated HER2-positive locally advanced or metastatic gastric or gastro-oesophageal junction adenocarcinoma (GATSBY): an international randomised, open-label, adaptive, phase 2/3 study

Discussion on the mechanism of HER2 resistance in esophagogastric junction and gastric cancer in the era of immunotherapy

Human epidermal growth factor receptor 2 (HER2) is a critical biomarker and therapeutic target in gastric/gastroesophageal junction (G/GEJ) cancers, despite the initial success of HER2-targeted therapies, such as trastuzumab, resistance to these drugs has emerged as a major impediment to effective long-term treatment. This review examines the mechanisms of drug resistance in HER2-positive G/GEJ cancer, the primary mechanisms of resistance explored include alterations in the HER2 receptor itself, such as mutations and changes in expression levels, as well as downstream signaling pathways, and interactions with the tumor microenvironment (TME). Furthermore, the review discusses the Novel therapeutic approaches, including the use of antibody-drug conjugates (ADCs) and combination therapies are assessed for their potential to enhance outcomes. By integrating recent research findings and clinical trials, this review aims to provide oncologists and researchers with insights into developing more effective treatments for patients with drug-resistant HER2-positive G/GEJ cancer.

Modulation of HER2 internalization enhances single-dose antibody-drug potency in HER2+ gastric cancer

HER2 is a membrane receptor tyrosine kinase overexpressed in 18-20% of gastric tumors. Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate (ADC) that targets HER2-positive (HER2+) cancer cells with a chemotherapeutic agent, emtansine. T-DM1 has low efficacy in HER2+ gastric cancer. This study explored the efficacy of combining drugs known to modulate HER2 internalization to enhance T-DM1 efficacy in gastric cancer. We used cholesterol-depleting drugs (lovastatin) to enhance HER2 membrane density. The irreversible pan-HER tyrosine kinase inhibitor neratinib was used to enhance the internalization of HER2-bound T-DM1. Therapy, pre-treatment and post-treatment positron emission tomography/computed tomography (PET/CT) were performed in both male and female mice. An enhancement of cell surface and internalized HER2 was observed after lovastatin and neratinib incubations, respectively. The combination of lovastatin with neratinib enhanced T-DM1 internalization in cancer cells. A decrease in HER2 protein levels and HER2 phosphorylation was detected in cells treated with T-DM1/lovastatin/neratinib when compared to control and T-DM1-only groups. PET/CT imaging of mice in the T-DM1/lovastatin/neratinib group showed a decrease in HER2 tumoral expression, which was associated with a decrease in tumor volume and sustained treatment efficacy in the T-DM1/lovastatin/neratinib group. This work demonstrates the therapeutic enhancement of T-DM1 using combination therapy with lovastatin/neratinib in gastric cancer. The treatment can be successfully monitored through PET/CT imaging.

Enhanced cytotoxicity of T-DM1 in HER2-low carcinomas via autophagy inhibition

Ado-trastuzumab emtansine (T-DM1), a conjugate of trastuzumab and the cytotoxic agent emtansine, has demonstrated significant antitumor efficacy in HER2-positive (HER2+) carcinoma. However, its effectiveness is limited against carcinoma cells with low HER2 expression (HER2-low). Here, we demonstrate that targeting autophagy enhances the cytotoxicity of T-DM1 against HER2-low SGC7901 cells, highlighting the potential of autophagy modulation in improving T-DM1-based therapies for HER2-low carcinomas. Specifically, this study shows that T-DM1 exhibits limited cytotoxic effects on SGC7901 cells, but pharmacological inhibition of autophagy enhances its cytotoxicity. Moreover, transmission electron microscopy revealed that autophagy activation involved the three key phases of autophagic flux: the formation, fusion, and degradation of autophagosomes, while immunoblot analysis confirmed a reduction in Akt/mTOR signaling. Furthermore, autophagy inhibition accelerated the fusion of T-DM1 with lysosomes in SGC7901 cells, as shown by confocal microscopy. Collectively, these findings suggest that while T-DM1 alone induces limited cytotoxicity, combining it with autophagy inhibitors enhances its efficacy against HER2-low carcinoma cells. Mechanistically, autophagy inhibition increases the binding of T-DM1 to lysosomes, potentially facilitating the release of emtansine from the conjugate. These results present a novel strategy that combines T-DM1 with autophagy inhibitors to effectively treat HER2-low gastric cancer, thereby broadening the therapeutic scope of T-DM1 to encompass previously challenging cancer types.

Gastric cancer

Gastric cancer remains a major health challenge worldwide, with nearly 1 million new cases annually contributing to more than 650 000 deaths. Epidemiologically, gastric cancer shows substantial geographical variation in incidence, with higher rates in Asia, South America, and eastern Europe, and a rapid increase in early-onset cases among people younger than 50 years. Key risk factors for gastric cancer include Helicobacter pylori infection, diet, obesity, smoking, and genetic predisposition. Early detection through comprehensive diagnostic procedures is crucial for optimising treatment outcomes. Standard treatment approaches for locally advanced gastric cancer include surgical resection, particularly D2 lymphadenectomy, complemented by chemotherapy and radiotherapy. There is increasing implementation of minimally invasive surgical techniques for operable disease and integration of immune checkpoint inhibitors and targeted therapies for advanced stages. Emerging therapies, such as novel targeted treatments and next-generation immunotherapies, show promise in improving survival and quality of life. Future directions in the management of gastric cancer focus on precision medicine, continued advancement in immunotherapy, novel early detection methods, and a multidisciplinary approach to care. These strategies aim to enhance the overall effectiveness of treatment and prognosis worldwide.

Adjuvant TRastuzumab deruxtecan plus fluoropyrimidine versus standard chemotherapy in HER2-positive gastric or gastroesophageal cancer patients with persistence of minimal residual disease in liquid biopsy after pre-operative chemotherapy and radical surgery: the multicentre, phase II randomized TRINITY trial

BACKGROUND

The standard treatment for localized/locally advanced gastroesophageal adenocarcinoma (GEA) is radical surgery and peri-operative FLOT treatment (5-fluorouracil plus leucovorin, oxaliplatin, and docetaxel), but around half patients still experience disease relapse. In gastrointestinal cancers, the presence of circulating tumor DNA (ctDNA) after surgery is associated with a high risk of relapse, and the lack of ctDNA clearance after post-operative treatment is strongly associated with early relapse. Therefore, liquid biopsy may guide the selection of patients with micrometastatic disease after preoperative chemotherapy and surgery for non-cross resistant regimens in the post-operative setting. Trastuzumab deruxtecan (T-DXd) is approved in patients with HER2-positive advanced gastric or gastroesophageal adenocarcinoma after failure of at least one prior trastuzumab-based regimen. The DESTINY-Gastric01 and 02 trials showed remarkable activity and efficacy of T-DXd, thus supporting the investigation of this agent in early-stage disease to increase the chance of achieving disease eradication. Finally, the DESTINY-Gastric03 trial showed the safety profile and feasibility, with preliminary promising activity results of the combination of T-DXd with a fluoropyrimidine.

TRIAL DESIGN

TRINITY is an ongoing multicentre, randomized, open-label, interventional phase II study which will enroll approximately 46 patients with HER2-positive GEA, treated with pre-operative FLOT and radical surgery, and with the persistence of minimal residual disease detected by the Signatera™ assay in a liquid biopsy collected between 2 and 6 weeks after surgery. The trial is designed with an observational phase enrolling patients with HER2-positive GEA eligible for standard treatment with peri-operative FLOT and surgery. Eligible patients will be randomized on a 1:1 basis to the experimental treatment arm consisting of adjuvant T-DXd (6.4 mg/kg IV on day 1) plus either capecitabine (1000 mg/sqm BID orally on days 1-14) or 5-fluorouracil (600 mg/sqm continuous IV infusion on days 1-5) Q3 W for 6 cycles, or to the control arm with standard post-operative FLOT (at the same dose used during the last pre-operative cycle) for 4 cycles. Patients non-eligible for the interventional trial will continue the standard therapy and follow-up in the frame of the observational phase with collection of exploratory longitudinal liquid biopsies. The primary objective is ctDNA clearance at 1 year after randomization. Considering alpha- and beta-errors of 0.10 and 0.20 and hypothesizing a ctDNA clearance of 10% and 35% in the control and experimental arm, respectively, 23 patients per arm are required to prove the superiority of the experimental strategy. Secondary endpoints include disease-free survival, overall survival, metastases-free survival, patient-reported outcomes and safety. The trial also represents a translational platform, including extensive analysis of circulating, tissue, and immune biomarkers as exploratory endpoints. Enrollment is active and ongoing.

TRIAL REGISTRATION

TRINITY is registered at ClinicalTrials.gov (NCT06253650).

Navigating the future of gastric cancer treatment: a review on the impact of antibody-drug conjugates

Gastric cancer, marked by its high incidence and poor prognosis, demands the urgent development of novel and effective treatment strategies, especially for patients ineligible for surgery or those who have had limited success with chemotherapy, radiotherapy and targeted therapies. Recently, antibody-drug conjugates (ADCs) have become a key area of investigation due to their high specificity and potent antitumor effects. These therapies combine monoclonal antibodies, designed to bind to tumor-specific antigens, with cytotoxic agents that selectively target and destroy malignant cells. ADCs have generated significant interest in clinical trials as a promising approach to improve both treatment efficacy and patient outcomes in gastric cancer. However, their clinical application is not without challenges and limitations that must be addressed. This review discusses the recent progress in the use of ADCs for gastric cancer treatment.

Evolving Landscape of HER2-Targeted Therapies for Gastric Cancer Patients

OPINION STATEMENT

Gastric cancer (GC) is a deadly disease worldwide, and trastuzumab in combination with chemotherapy has been the standard first-line treatment for HER2-positive GC following the TOGA trial. Besides adjuvant therapy, HER2-directed therapy is widely used as neoadjuvant or translational therapy, and survival benefit even surgical opportunities is seen in these patients. However, resistance is not rare in recent years, and the second-line treatment for trastuzumab beyond progression has received widespread attention in GC. Moreover, current evidence cannot recommend trastuzumab for patients with IHC1+ HER2 low expression GC yet. Researchers are currently investigating whether GC patients with low HER2 expression could also benefit from HER2-directed therapies. In addition to using HER2 as a target for targeted therapy, HER2-mediated targeted delivery of cytotoxic drugs and targeted immunity have made important contributions to overcoming trastuzumab resistance in recent trials. HER2/neu-derived peptide epitopes vaccination and HER2-specific chimeric antigen receptor (CAR) therapy focus on reestablishing anti-tumor immunity in different ways and show significant anti-tumor activity. Other antibodies that target different regions of the HER2 receptor or block key downstream pathways such as AKT or PI3K also offer potential anti-tumor activity against HER2. HER2 use in GC will not be hampered by resistance or low expression and will play a bigger role. We review the current efforts to enable GC patients with trastuzumab-resistant and HER2 low-expressing accessible to HER2 targeted therapy and present our consideration for future HER2 in GC.

Differences in treatment outcome between translational platforms in developing therapies for gastrointestinal cancers

The variability in translational models profoundly impacts the outcomes and predictive value of preclinical studies for gastrointestinal (GI) cancer treatments. Preclinical models, including 2D cell cultures, 3D organoids, patient-derived xenografts (PDXs), and animal models, provide distinct advantages and limitations in replicating the complex tumor microenvironment (TME) of human cancers. Each model's unique biological and structural differences contribute to discrepancies in treatment responses, challenging the direct translation of experimental results to clinical settings. While 2D cell cultures are cost-effective and suitable for high-throughput screening, they lack the 3D architecture and cellular interactions of the in vivo TME. Organoids offer a more comprehensive 3D structure that better mirrors tumor heterogeneity, yet they still face limitations in fully mimicking in vivo conditions, such as vascularization and immune cell interactions. PDXs, although more representative of human cancers due to their genetic fidelity and TME preservation, are costly and resource-intensive, with human stromal and immune components gradually replaced by murine counterparts over time. This review assesses the strengths and limitations of each model, highlighting recent advancements in translational platforms that incorporate complex TME features. Understanding the influence of model selection on treatment efficacy predictions is essential for enhancing the reliability of preclinical findings and advancing personalized therapeutic strategies for GI cancers.

Development of treatment strategies for advanced HER2-positive gastric cancer: Insights from clinical trials

HER2-positive gastric cancer (GC), a unique molecular subtype, has garnered significant interest in recent years. Here, we review clinical trial data on advanced HER2-positive GC from the past 15 years. Trastuzumab plus standard chemotherapy remain the first-line treatment. The initial survival benefits conferred by immune checkpoint inhibitors plus trastuzumab and standard chemotherapy are encouraging. The combination of ramucirumab and mono-chemotherapy, as well as the antibody conjugated drug trastuzumab deruxtecan, is the recommended second-line regimen. Treatment with immune checkpoint inhibitors plus ramucirumab and mono-chemotherapy shows promise. Despite the limited treatment options for third line and beyond, development of novel therapeutic strategies is expected. Although clinical cure of advanced HER2-positive GC is unlikely, current clinical studies offer valuable insight into regimens that prolong survival.

Targeting HER2 in Gastroesophageal Cancer: A New Appetite for an Old Plight

The incidence of gastroesophageal cancers is rising, driven, in part, by an increasing burden of risk factors of obesity and gastroesophageal reflux. Despite efforts to address these risk factors, and a growing interest in methods of population screening, the bulk of these tumours are unresectable at diagnosis. In this setting, effective systemic treatments are paramount to improve survival and quality of life. Early and accurate identification of oncogenic drivers, such as human epidermal growth factor receptor 2 (HER2), present in 5-30% of gastroesophageal adenocarcinomas (GEAs), is integral to guide choice of therapies due to the clear predictive implications that arise from overexpression of this receptor. After trastuzumab, the first anti-HER2 agent with approved use in HER2-positive GEA, the addition of pembrolizumab to first-line trastuzumab-chemotherapy and trastuzumab deruxtecan in the refractory space have more recently changed practice. Yet, the response to these agents has been vastly different across patients with HER2-positive disease, underpinning the need for reliable biomarkers of response. Emergent data have suggested that levels of HER2 expression on tissue or liquid biopsies may predict response to first-generation HER2 therapies while HER2 heterogeneity, receptor changes, co-occurring molecular alterations and oncogenic genomic and metabolic reprogramming may be implicated in resistance. A robust knowledge of the mechanisms of resistance and response to HER2-directed therapies is necessary to inform novel strategies of HER2-targeting and guide choice combinations with other biomarker-directed therapies, to improve outcomes from a new generation of clinical trials in HER2-positive GEA. Understanding and close examination of previous failures in this space form an important part of this assessment, as does correlative biomarker and translational work pertaining to the role of HER2 and dynamic changes that result through treatment exposure. In this review, we aim to provide an overview of strategies for HER2 targeting, summarising both the successes and disappointments in this therapeutic landscape and discuss existing challenges and future perspectives on development in this highly morbid tumour type.

Disitamab vedotin in preclinical models of HER2-positive breast and gastric cancers resistant to trastuzumab emtansine and trastuzumab deruxtecan

BACKGROUND

Most HER2-positive breast or gastric cancers eventually become resistant to the approved anti-HER2 antibody-drug conjugates (ADC) trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd). Disitamab vedotin (DV) is a novel anti-HER2 ADC that binds to a different epitope on HER2 compared to trastuzumab. We assessed the efficacy of DV in breast and gastric cancer cell lines and xenografts, including tumor models resistant to T-DM1 and T-DXd. Additionally, we investigated whether combining two anti-HER2 ADCs could enhance the efficacy of the individual ADCs.

METHODS

The efficacy of DV, T-DM1, and T-DXd, both as single agents and in combinations, was assessed using an AlamarBlue cell proliferation assay in HER2-positive breast and gastric cancer cell lines, including those resistant to T-DM1 and T-DXd. The efficacy of DV was evaluated also in breast and gastric cancer SCID mouse xenografts that had progressed on T-DM1 and/or T-DXd. ADC combinations were tested in breast and gastric cancer xenografts.

RESULTS

DV was effective in cell lines resistant to T-DM1 and/or T-DXd, and it inhibited the growth of breast and gastric cancer xenografts that had progressed on T-DM1 and/or T-DXd. The combinations of DV plus T-DM1 and DV plus T-DXd showed greater efficacy than the corresponding single agents in both breast and gastric cancer cell lines and xenografts.

CONCLUSIONS

DV was effective in treating breast and gastric cancer xenograft tumors resistant to T-DM1 and/or T-DXd. The combination of DV with T-DM1 or T-DXd demonstrated promising activity.

Is ADC a rising star in solid tumor? An umbrella review of systematic reviews and meta-analyses

BACKGROUND

Antibody-drug conjugates (ADCs) combine the specificity of monoclonal antibodies with the potency of highly cytotoxic drugs and are known as panaceas, completely changing the treatment paradigm for solid tumors. Compared with other anti-cancer drugs, do they have better efficacy and lower toxicity risks? It is necessary to summarize and analyze the published clinical research data in this area to provide additional evidence-based evidence for clinical practice.

OBJECTIVE

To comprehensively assess and overview the efficacy and safety of antibody-drug conjugates for the treatment of solid tumors.

DESIGN

An umbrella review of systematic reviews and meta-analyses.

METHODS

Systematic search of eight electronic databases and one registration platform including Embase, PubMed, Cochrane Database of Systematic Reviews (CDSR), Web of Science (WoS), China National Knowledge Infrastructure (CNKI), Chinese BioMedical Literature Database (CBM), Wan Fang Data, China Science and Technology Journal Database (VIP) and international prospective register of systematic reviews (PROSPERO) on Aug 1, 2024, to identify relevant systematic reviews or meta-analyses. Three authors completed research screening and data extraction independently. AMSTAR 2 was used to evaluate the methodological quality of the included studies and the Grading of Recommendations Assessment, Development and Evaluation Working Group (GRADE) was performed to evaluate the quality of the evidence. We examined progression-free survival (PFS), overall survival (OS), objective response rate (ORR) as efficacy endpoints, and the incidence of adverse events (AEs) as safety profiles.

RESULTS

A total of 16 eligible publications, including 32 clinical studies, were included in the umbrella review. The methodological quality of the included study was poor, with 2 articles of moderate-quality (12.5%), 5 articles of low quality (31.25%), and 9 articles of critically low quality (56.25%). Only one third of the evidence was of high quality. Within the included studies, breast cancer accounted for four-fifths, 2 studies were gastric cancer, and 1 study was a solid tumor. The overall results showed that ADCs significantly increased PFS and OS in patients with solid tumors, and the risk of toxicity was within an acceptable range. ado-Trastuzumab emtansine (T-DM1) and Trastuzumab deruxtecan (T-Dxd) treatment of human epidermal growth factor receptor 2(HER2) low/positive advanced metastatic breast cancer significantly prolonged PFS and OS, but the ORR showed a significant advantage. Compared with the chemotherapy group, T-Dxd significantly prolonged OS and PFS in gastric cancer patients, while T-DM1 did not. In other cancer types (ovarian cancer, renal cell carcinoma, and malignant pleural mesothelioma), ADCs tended to extend overall survival or progression-free survival compared with controls, but the difference was not statistically significant.

CONCLUSIONS

Based on the available evidence, in breast cancer, ADCs were proved to with significant improvements in prolonging survival time and demonstrates a tolerable safety profile. Meanwhile, ADCs were proved to have enormous potential for the treatment of solid tumors. However, well-designed, multi-center RCTs need to further identify its potential in various solid tumors.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD 42,024,564,517.

Efficacy and safety of different drugs in patients with HER2-positive gastric cancer: network meta-analysis

BACKGROUND

In the past decade, there has been a significant advancement in targeted therapy and immunotherapy, leading to the discovery of new drugs and changes in the treatment approach for patients with HER2-positive gastric cancer. Although several drugs are available for treating these patients, there is still no consensus on their selection, and there has been limited direct or indirect comparison among them.

OBJECTIVE

To address this gap, a network meta-analysis was conducted to assess the efficacy and safety of different drugs used in the treatment of HER2-positive gastric cancer.

METHODS

By searching through databases such as PubMed, Embase, Web of Science, and Cochrane Library, we identified 16 randomized controlled trials that involved a total of 4485 patients and utilized 9 different intervention measures.

RESULTS

Based on the current evidence, compared with chemotherapy alone, the hazard ratio (HR) of overall survival (OS) and progression-free survival (PFS) in gastric cancer patients treated with nivolumab were [hazard ratio (HR): 2.61 95%confidence interval (CI) (1.51, 4.51)] and [hazard ratio (HR): 2.01 95% confidence interval (CI) (1.18, 3.42)], respectively. Compared with chemotherapy alone, the hazard ratio (HR) of overall survival (OS) and progression-free survival (PFS) in gastric cancer patients treated with trastuzumab deruxtecan were [hazard ratio (HR): 1.7 95% confidence interval (CI) (1.13, 2.56)] and [hazard ratio (HR): 2.13 95% confidence interval (CI) (1.42, 3.22)], respectively. It is suggested that nivolumab and trastuzumab deruxtecan can effectively prolong overall survival (OS) and progression-free survival(PFS) in patients with HER2-positive gastric cancer, while also reducing the risk of adverse events to some extent. Therefore, these two regimens, nivolumab and trastuzumab deruxtecan, are considered to be effective and safe options for the treatment of patients with HER2-positive gastric cancer.

CONCLUSIONS

In previous studies, trastuzumab-based chemotherapy has been a common treatment for HER2-positive gastric cancer. To a certain extent, our study provides a reliable direction for future treatment options for HER2-positive gastric cancer.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023420941.

Targeted therapy and immunotherapy for gastric cancer: rational strategies, novel advancements, challenges, and future perspectives

Gastric cancer (GC) is one of the most common malignant tumors worldwide, and its treatment has been a focus of medical research. Herein we systematically review the current status of and advancements in targeted therapy and immunotherapy for GC, which have emerged as important treatment strategies in recent years with great potential, and summarize the efficacy and safety of such treatments. Targeted therapies against key targets in GC, including epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), and vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR), have shown remarkable therapeutic efficacies by inhibiting tumor progression and/or blood supply. In particular, markable breakthroughs have been made in HER2-targeting drugs for HER2-positive GC patients. To address intrinsic and acquired resistances to HER2-targeting drugs, novel therapeutic agents including bispecific antibodies and antibody-drug conjugates (ADC) targeting HER2 have been developed. Immunotherapy enhances the recognition and elimination of cancer cells by activating body anticancer immune system. Programmed cell death protein 1 (PD-1) and programmed cell death-ligand 1 (PD-L1) antibodies are the most commonly used immunotherapeutic agents and have been used with some success in GC treatment. Innovative immunotherapy modalities, including adoptive immune cell therapy, tumor vaccines, and non-specific immunomodulators therapy, and oncolytic viruses have shown promise in early-stage clinical trials for GC. Clinical trials have supported that targeted therapy and immunotherapy can significantly improve the survival and quality of life of GC patients. However, the effects of such therapies need to be further improved and more personalized, with advancement in researches on tumor immune microenvironment. Further studies remain needed to address the issues of drug resistance and adverse events pertaining to such therapies for GC. The combined application of such therapies and individualized treatment strategies should be further explored with novel drugs developed, to provide more effective treatments for GC patients.

Contemporary management of advanced gastric and gastroesophageal adenocarcinomas

INTRODUCTION

Gastric and gastroesophageal adenocarcinomas (GEACs) continue to carry a poor prognosis in most patients. New and exciting therapies have entered the treatment landscape in recent years. Prior to these recent approvals, treatment advances had been limited.

AREAS COVERED

Important treatment decision biomarkers for metastatic GEAC are microsatellite instability-high/deficient mismatch repair, human epidermal growth factor receptor-2, programmed-death ligand 1, and claudin 18.2 expression among others (such as Epstein Barr Virus (EBV) and agnostic biomarkers). Results of these biomarkers drive therapy decisions. Second-line treatment in most cases is less biomarker driven and needs further progress.

EXPERT OPINION

Studies of molecular subsets in GEAC has led to the understanding that these are heterogenous diseases that need to be treated differently. Other biomarkers with targeted therapies are being studied including fibroblast growth factor receptor, trophoblast cell surface antigen-2, and epidermal growth factor receptor. Additionally, epidemiological distinctions are starting to drive therapy such as in EBV in GAC.

A literature review of recent advances in gastric cancer treatment: exploring the cross-talk between targeted therapies

BACKGROUND

Gastric cancer (GC) ranks fourth in global mortality rates and fifth in prevalence, making it one of the most common cancers worldwide. Recent clinical studies have highlighted the potential of immunotherapies as a promising approach to treating GC. This study aims to shed light on the most impactful therapeutic strategies in the context of GC immunotherapy, highlighting both established and emerging approaches.

MAIN BODY

This review examines over 160 clinical studies conducted globally, focusing on the effectiveness of various immunotherapy modalities, including cancer vaccines, adoptive cell therapy, immune checkpoint inhibitors (ICIs), and monoclonal antibodies (mAbs). A comprehensive search of peer-reviewed literature was performed using databases such as Web of Science, PubMed, and Scopus. The selection criteria included peer-reviewed articles published primarily within the last 10 years, with a focus on studies that provided insights into targeted therapies and their mechanisms of action, clinical efficacy, and safety profiles. The findings indicate that these immunotherapy strategies can enhance treatment outcomes for GC, aligning with current treatment guidelines. ICIs like pembrolizumab and nivolumab have shown significant survival benefits in specific GC subgroups. Cancer vaccines and CAR-T cell therapies demonstrate potential, while mAbs targeting HER2 and VEGFR pathways enhance outcomes in combination regimens. We discuss the latest advancements and challenges in targeted therapy and immunotherapy for GC. Given the evolving nature of this field, this research emphasizes significant evidence-based therapies and those currently under evaluation rather than providing an exhaustive overview. Challenges include resistance mechanisms, immunosuppressive tumor environments, and inconsistent results from combination therapies. Biomarker-driven approaches and further research into emerging modalities like CAR-T cells and cancer vaccines are critical for optimizing treatments.

CONCLUSIONS

Immunotherapy is reshaping GC management by improving survival and quality of life. Ongoing research and clinical evaluations are crucial for refining personalized and effective therapies.

Current Landscape of Molecular Biomarkers in Gastroesophageal Tumors and Potential Strategies for Co-Expression Patterns

The treatment of metastasized gastroesophageal adenocarcinoma largely depends on molecular profiling based on immunohistochemical procedures. Therefore, the examination of HER2, PD-L1, and dMMR/MSI is recommended by the majority of clinical practice guidelines, as positive expression leads to different treatment approaches. Data from large phase-III trials and consequent approvals in various countries enable physicians to offer their patients several therapy options including immunotherapy, targeted therapy, or both combined with chemotherapy. The introduction of novel therapeutic targets such as CLDN18.2 leads to a more complex decision-making process as a significant number of patients show positive results for the co-expression of other biomarkers besides CLDN18.2. The aim of this review is to summarize the current biomarker landscape of patients with metastatic gastroesophageal tumors, its direct clinical impact on daily decision-making, and to evaluate current findings on biomarker co-expression. Furthermore, possible treatment strategies with multiple biomarker expression are discussed.

A phase Ia study of a novel anti-HER2 antibody-drug conjugate GQ1001 in patients with previously treated HER2 positive advanced solid tumors

BACKGROUND

A novel anti-human epidermal growth factor receptor 2 (HER2) antibody-drug conjugate (ADC) GQ1001 was assessed in patients with previously treated HER2 positive advanced solid tumors in a global multi-center phase Ia dose escalation trial.

METHODS

In this phase Ia trial, a modified 3 + 3 study design was adopted during dose escalation phase. Eligible patients were enrolled, and GQ1001 monotherapy was administered intravenously every 3 weeks. The starting dose was 1.2 mg/kg, followed by 2.4, 3.6, 4.8, 6.0, 7.2 and 8.4 mg/kg. Extra patients were enrolled into 6.0, 7.2, and 8.4 mg/kg cohorts as dose expansion phase. The primary endpoints were safety and to determine the maximum tolerated dose (MTD) based on dose limiting toxicities (DLTs). Pharmacokinetics and anti-tumor efficacy of GQ1001 were assessed. The plasma concentration of free DM1, the payload of GQ1001, was quantitated.

RESULTS

A total of 32 patients were enrolled, predominantly in breast (9), gastric or gastro-esophageal junction (9) and salivary gland cancer (4). Median number of prior-line of therapies was 3 (0-11) and 37.5% patients received ≥ 2 lines of anti-HER2 therapies. No DLT was observed during dose escalation. MTD was not reached and dose recommended for dose expansion (DRDE) was determined as 8.4 mg/kg. Grade ≥ 3 treatment-related adverse events rate was 28.1% (9/32) and platelet count decreased (4/32, 12.5%) was the most common one. No drug-related death was observed. Objective response rate and disease control rate of 15 evaluable patients in 7.2 mg/kg and 8.4 mg/kg cohorts were 40.0% (6/15) and 60.0% (9/15). Pharmacokinetics analysis showed low exposure and accumulation of free DM1 in circulation.

CONCLUSION

GQ1001 is well tolerated and shows promising efficacy in previously treated HER2-positive advanced solid tumors. DRDE was determined as 8.4 mg/kg for following trials. Trial registration NCT, NCT04450732, Registered 23 June 2020, https://clinicaltrials.gov/study/NCT04450732.

DKK1 and Its Receptors in Esophageal Adenocarcinoma: A Promising Molecular Target

Esophageal adenocarcinoma (EAC) is an aggressive gastrointestinal (GI) malignancy with increasing incidence. Despite the recent progress in targeted therapies and surgical approaches, the survival rates of esophageal adenocarcinoma patients remain poor. The Dickkopf (DKK) proteins are secretory proteins known mainly as antagonists of the Wnt/β-catenin signaling pathway, which is considered an oncogene. However, it has been shown that in several GI cancers, including esophageal cancer, DKK1 may act as an oncogene itself through Wnt-independent signaling pathways. LRP5\6 and Kremen1/2 (Krm1/2) are transmembrane receptors to which the DKK proteins are mainly known to bind. CKAP4 (cytoskeleton-associated protein 4) is a novel receptor of DKK1, and the DKK1-CKAP4 pathway seems to be crucial in the role of DKK1 as an oncogene. The aim of this review is to feature the essential role of DKK1 and its receptors in carcinogenesis with a focus on EAC in an era of urgent need for specific biomarkers along with improved targeted therapies.

Emerging Trends in the Management of Gastric Malignancy with Peritoneal Dissemination: Same Disease, Heterogeneous Prognosis

Gastric cancer is a significant global contributor to cancer-related mortality. Stage IV gastric cancer represents a significant percentage of patients in Western countries, with peritoneal dissemination being the most prevalent site. Peritoneal disease comprises two distinct entities, macroscopic (P1) and microscopic (P0CY1), which are associated with poor long-term survival rates. Although the present standard of treatment is palliative chemotherapy, a global controversy has arisen concerning specific patients with limited disease burden or conversion to negative lavage cytology following chemotherapy. Available approaches include systemic or intraperitoneal chemotherapy, upfront gastrectomy, and conversion surgery. This review consolidated the current evidence regarding multimodal management, indicating prolonged survival for this distinct subgroup of patients. Considering the complexity of peritoneal metastases, the potential of the multimodal approach unveils promising prospects for identifying the optimal treatment for this particular subset of stage IV patients and thus enhancing their survival outcomes.

Human Epidermal Growth Factor Receptor 2 Positive Advanced Gastric or Esophagogastric Adenocarcinoma: Reflecting on the Past to Gain a New Insights

PURPOSE OF REVIEW

Human epidermal growth factor receptor 2 (HER2) is a critical target in advanced gastric cancer (AGC). This review highlights the current treatment landscape, lessons learned from past clinical trials, and prospects for future treatment strategies for HER2-positive AGC.

RECENT FINDINGS

Trastuzumab had been the standard treatment for HER2-positive AGC for a decade, and subsequently, trastuzumab deruxtecan, an antibody-drug conjugate (ADC), emerged with an impressive response. Recently, the addition of pembrolizumab to first-line chemotherapy plus trastuzumab has become a novel standard treatment. Past clinical trials of HER2-targeted therapies, which succeeded in HER2-positive breast cancer but failed in AGC, have deepened our understanding of resistance mechanisms. Based on these results, several clinical trials of novel HER2-targeted therapies, including immunologic approaches such as CAR-T cells and vaccines, are currently ongoing. Circulating tumor DNA is also expected to be a tool for real-time biomarker analysis. Additionally, ADCs with a bystander effect have the potential to expand the scope of HER2-targeted therapies to HER2-expressing, including HER2-low AGC. Learning from past trials, further development of novel HER2-targeted therapies is underway, expanding their scope to HER2-expressing AGC. Meanwhile, selecting optimal treatment is a challenging issue in cases with HER2-low AGC overlapping with other biomarkers like CLDN18.2.

Sustained Clinical Complete Response after Discontinuation of Trastuzumab-deruxetecan Due to Interstitial Pneumonia for HER2-positive Gastric Adenocarcinoma with Enteroblastic Differentiation (GAED)

Trastuzumab deruxtecan (T-DXd) has demonstrated remarkable efficacy as a third- or later-line chemotherapy for human epidermal growth factor receptor 2 (HER2)-positive advanced gastric and gastroesophageal junction adenocarcinomas. However, it may cause pneumonitis, and its efficacy in rare histologies such as gastric adenocarcinoma with enteroblastic differentiation (GAED) remains unclear. A 74-year-old woman with unresectable HER2-positive GAED and lung metastasis received T-DXd as a fifth-line chemotherapy. Treatment was discontinued after 15 cycles owing to drug-induced pneumonitis; however, the patient achieved a sustained complete response for 14 months without subsequent chemotherapy or the exacerbation of pneumonitis. T-DXd was effective in HER2-positive GAED.

Perioperative Treatment in Gastric Cancer: A Fast-Changing Field

Gastric cancer is the fifth most common cancer worldwide and its incidence is rising. Surgery is the only curative strategy and its association with perioperative chemotherapy is now standard treatment for most resectable tumors. Despite treatment advances, disease relapse is high, even in early stages, and continued improvement in curative treatment is imperative. With deeper knowledge of gastric cancer heterogeneity, molecular subtypes, and the tumor immune microenvironment, new standard treatment strategies may emerge in the near future. This paper provides a comprehensive review of the current treatment landscape in resectable gastric cancer and future perspectives for the next decade regarding new agents such as targeted therapies, immunotherapy, antibody-drug conjugates, and the combination of multiple treatment modalities.

Generation of chimeric antigen receptor T cells targeting p95HER2 in solid tumors

The redirection of T lymphocytes against tumor-associated or tumor-specific antigens, using bispecific antibodies or chimeric antigen receptors (CAR), has shown therapeutic success against certain hematological malignancies. However, this strategy has not been effective against solid tumors. Here, we describe the development of CAR T cells targeting p95HER2, a tumor-specific antigen found in HER2-amplified solid tumors. These CAR T cells display robust activity against p95HER2-expressing cell lines but demonstrate limited efficacy against patient-derived xenografts. As p95HER2 is invariably detectable on tumor cells that overexpress HER2, but not those that express HER2 at normal levels, we arm p95HER2-specific CAR T cells with affinity-tuned bispecific antibodies against HER2 and CD3 in order to redirect them only to HER2-amplified cells. The combination of p95HER2.CAR T cells and HER2 x CD3 bispecific antibodies lead to a complete regression in three HER2-positive, patient-derived mouse xenografts tumor models. This combination represents a promising strategy to redirect T cells against a subset of HER2-positive tumors.

Evolving Treatment Landscape for Advanced Esophageal and Gastroesophageal Junction Adenocarcinoma

PURPOSE OF REVIEW

This review highlights advances and recent changes in the treatment paradigm for advanced esophageal adenocarcinoma (EAC) and gastroesophageal junction adenocarcinoma (GEJAC).

RECENT FINDINGS

Chemotherapy remains the backbone of treatment for advanced EAC/GEJAC. New targets/agents include immunotherapy, HER-2, claudin18.2, and FGFR2b, with various mechanisms (CAR-T, bispecific mAB, ADCs) altering the treatment landscape against these targets. The approaches to these targets may act together, in sequence, and even synergistically to improve outcomes. Herein, we review the state of the field, including highlighting ongoing clinical trials and additional emerging agents and approaches.

Efficacy and safety of dual blockade of HER2 and PD-1 in patients with HER2-positive gastric cancer: a retrospective, multicentre study

Human epidermal growth factor receptor 2 (HER2) expression is one of the most important pathological characteristics of gastric cancer. The positive rate of HER2 expression in patients with gastric cancer is approximately 20%. The phase III Keynote-811 study revealed that anti-HER2 and anti-PD-1 therapy combined with chemotherapy could significantly improve the objective response rate as first-line treatment in patients with HER2-positive advanced gastric cancer. In the present study, we aimed to evaluate the efficacy of combination therapy with trastuzumab and PD-1 inhibitors in patients with advanced HER2-positive gastric cancer in a real-world setting. Seventy-two HER2-positive gastric cancer patients from three hospitals in China were retrospectively reviewed. These patients were treated with trastuzumab plus one anti-PD-1 agent with or without chemotherapy. The overall response rate, progression-free survival and overall survival were assessed according to the Response Evaluation Criteria in Solid Tumours (RECIST 1.1). From January 2018 to October 2021, 72 patients with HER2-positive gastric cancer received trastuzumab and a PD-1 inhibitor with or without chemotherapy as neoadjuvant chemotherapy, first-line therapy, second-line therapy or salvage therapy. The ORR was 54.2% for all patients and 79.4% for previously untreated patients. The median PFS and median OS were 10 months (95% CI: 8-13 months) and 26.1 months (95% CI: 18.5-NA months), respectively, for all patients. Grade 3 adverse effects occurred in approximately 25% of patients. Immune-related adverse effects occurred in approximately 12.5% of patients. Trastuzumab and PD-1 inhibitor combination therapy with or without chemotherapy achieved satisfactory survival outcomes in patients with HER2-positive gastric cancer with acceptable safety.

Dual HER2 inhibition: Is two better than one?

Li et al. present data from a randomized frontline phase II trial in HER2+ gastroesophageal cancers exploring dual targeting of HER2 with HLX22 (a novel HER2-specific antibody) with HLX02 (a trastuzumab biosimilar) and capecitabine/oxaliplatin chemotherapy. While the objective response and progression-free survival are encouraging, the future development of the combination in a crowded HER2 space remains unclear.

Autoimmune complications of tyrosine kinase inhibitors in cancer therapy: Clinical insights, mechanisms, and future perspectives

The tyrosine kinase inhibitors (TKIs) have emerged as a promising class of novel anticancer drugs, achieving significant success in clinical applications. However, the risk of autoimmune diseases associated with these drugs has raised widespread concerns. In this review, TKI-induced autoimmune diseases are reviewed in order to understand this complex phenomenon through clinical research and molecular mechanism exploration. Despite the relatively low incidence of autoimmune diseases, their potential severity demands heightened attention. The potential mechanisms underlying TKI-induced autoimmune diseases may involve immune system dysregulation, alterations in immune cell function, activation of inflammatory responses, and attacks on self-antigens. Various preventive strategies, including clinical monitoring, personalized treatment, optimization of therapeutic approaches, and patient education and communication, can be employed to effectively address these potential risks. Future research directions should delve into the molecular mechanisms of TKI-induced autoimmune diseases, integrate studies on genetics and immunogenetics, advance the development of novel TKIs, explore the possibilities of combining immunotherapy with TKI treatment, and propel large-scale clinical trials.

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.

A signal-seeking phase 2 study of Trastuzumab emtansine in tumours harbouring HER2 amplification or mutation

This single-arm phase II non-randomised trial (ACTRN12619001265167) evaluated trastuzumab emtansine in solid cancers with HER2 amplification or mutation detected by comprehensive genomic profiling. The primary objective was objective response (OR), while secondary objectives included the time to progression (TTP) on study to TTP on prior therapy ratio, progression-free survival (PFS) and overall survival (OS). The cohort included 16 tumours with HER2 mutations (group 1) and 16 with HER2 amplification (group 2). After 17 months median follow-up, ORs occurred in 19% of group 1 (1 salivary gland carcinoma (SGC), 2 lung cancers) and 25% of group 2 (3 SGCs, 1 uterine carcinoma). Fourteen of 29 TTP-evaluable patients achieved a TTP ratio ≥1.3, including 10 without an OR. Median PFS and OS were 4.5 (95% CI 2.1-7.0) and 18.2 months (95% CI 8.1-not reached) respectively. Trastuzumab emtansine showed modest ORs and a favourable change in disease trajectory in select HER2-altered solid cancers.

Antibody-drug conjugates in gastric cancer: from molecular landscape to clinical strategies

Antibody-drug conjugates (ADCs) represent a crucial component of targeted therapies in gastric cancer, potentially altering traditional treatment paradigms. Many ADCs have entered rigorous clinical trials based on biological theories and preclinical experiments. Modality trials have also been conducted in combination with monoclonal antibody therapies, chemotherapies, immunotherapies, and other treatments to enhance the efficacy of drug coordination effects. However, ADCs exhibit limitations in treating gastric cancer, including resistance triggered by their structure or other factors. Ongoing intensive researches and preclinical experiments are yielding improvements, while enhancements in drug development processes and concomitant diagnostics during the therapeutic period actively boost ADC efficacy. The optimal treatment strategy for gastric cancer patients is continually evolving. This review summarizes the clinical progress of ADCs in treating gastric cancer, analyzes the mechanisms of ADC combination therapies, discusses resistance patterns, and offers a promising outlook for future applications in ADC drug development and companion diagnostics.

HER2-low gastric cancer: is the subgroup targetable?

Therapeutic developments in the targeting of human epidermal growth factor receptor 2 (HER2)-expressing gastric cancer have followed the dramatic success of HER2-expressing breast cancer treatment, which has facilitated the expansion of indications for anti-HER2 agents to include not only conventional HER2-positive breast cancer, but also HER2-low and HER2-ultralow subgroups. The targetability of HER2-low gastric cancer, however, has yet to be established. Hence, further studies are needed to comprehensively understand the clinicopathological features, specific gene alterations, and distinct tumor immune microenvironment of HER2-low gastric cancer and compare them with those for HER2-positive or -negative gastric cancer. Antibody-drug conjugates for HER2 play an important role in making HER2-low gastric cancer targetable. In this context, a deeper understanding of the novel anti-HER2 agents, including antibody-drug conjugates, bispecific T-cell engager antibodies, and a combination of these agents, as well as new forms of immunomodulatory agents are also required. Redefining and re-categorizing HER2 status through not only immunohistochemistry/fluorescence in situ hybridization but also evaluating ERRB2 copy number gain or protein overexpression levels measured using DNA or RNA sequencing might be helpful for identifying populations with HER2-expressing tumors who would ideally benefit from anti-HER2 treatment. The current paper reviewed recent clinical trials, focusing particularly on HER2-low gastric cancer together with basic/translational findings, and discuss perspectives on further therapeutic development in the treatment of this distinct subgroup.

HER2-targeted therapies beyond breast cancer - an update

The receptor tyrosine-kinase HER2 (also known as ErbB2) is a well-established therapeutic target in patients with breast or gastric cancer selected on the basis of HER2 overexpression on immunohistochemistry and/or ERBB2 amplification on in situ hybridization. With advances in cancer molecular profiling and increased implementation of precision medicine approaches into oncology practice, actionable HER2 alterations in solid tumours have expanded to include ERBB2 mutations in addition to traditional HER2 overexpression and ERBB2 amplification. These various HER2 alterations can be found in solid tumour types beyond breast and gastric cancer, although few HER2-targeted therapeutic options have been established for the other tumour types. Nevertheless, during the 5 years since our previous Review on this topic was published in this journal, obvious and fruitful progress in the development of HER2-targeted therapies has been made, including new disease indications, innovative drugs with diverse mechanisms of action and novel frameworks for approval by regulatory authorities. These advances have culminated in the recent histology-agnostic approval of the anti-HER2 antibody-drug conjugate trastuzumab deruxtecan for patients with HER2-overexpressing solid tumours. In this new Review, we provide an update on the current development landscape of HER2-targeted therapies beyond breast cancer, as well as anticipated future HER2-directed treatment strategies to overcome resistance and thereby improve efficacy and patient outcomes.

HER-2 directed therapies across gastrointestinal tract cancers - A new frontier

Gastrointestinal (GI) cancers are common and in the metastatic setting they have a poor prognosis. The current mainstay of treatment of GI cancers is chemotherapy; however, the biomarker-directed treatment landscape is evolving. HER-2 is overexpressed in a portion of GI cancers and is an emerging target for therapy, with recent FDA tumor agnostic approval for trastuzumab deruxtecan. Testing for HER-2 expression is not standardized across GI cancers, methodology requires further optimization and standardization as HER-2 targeted therapy emerges into the treatment landscape. There is established rationale for use of HER-2 targeted therapy in first line treatment of metastatic gastric cancer, and emerging evidence with variable benefit in bile duct, pancreatic and colorectal cancers.

Antibody-drug conjugates for hepato-pancreato-biliary malignancies: "Magic bullets" to the rescue?

Hepato-Pancreato-Biliary (HPB) malignancies constitute a highly aggressive group of cancers that have a dismal prognosis. Patients not amenable to curative intent surgical resection are managed with systemic chemotherapy which, however, confers little survival benefit. Antibody-Drug Conjugates (ADCs) are tripartite compounds that merge the intricate selectivity and specificity of monoclonal antibodies with the cytodestructive potency of attached supertoxic payloads. In view of the unmet need for drugs that will enhance the survival rates of HPB cancer patients, the assessment of ADCs for treating HPB malignancies has become the focus of extensive clinical and preclinical investigation, showing encouraging preliminary results. In the current review, we offer a comprehensive overview of the growing body of evidence on ADC approaches tested for HPB malignancies. Starting from a concise discussion of the functional principles of ADCs, we summarize here all available data from preclinical and clinical studies evaluating ADCs in HPB cancers.

The Impact of Pembrolizumab as a Salvage Therapy Based on HER2 Expression in Advanced Gastric Cancer

Immune checkpoint inhibitors (ICIs) are used as salvage treatments for advanced gastric cancer (AGC) regardless of HER2 status. This study assessed the efficacy of ICIs based on HER2 expression in AGC patients who received pembrolizumab as salvage monotherapy at Samsung Medical Center from November 2017 to March 2023. HER2 status was determined via immunohistochemistry, and tumor response and survival outcomes were compared accordingly. Among the 113 patients analyzed, with a median age of 61 years and 64.6% being male, 12 patients (10.6%) were HER2-positive, and 101 patients (89.4%) were HER2-negative. Of 92 evaluable patients, none had a complete response. However, 50% of HER2-positive patients had a partial response, compared to 4.9% of HER2-negative patients (p < 0.001). The disease control rate was 70% in HER2-positive and 37.8% in HER2-negative patients (p = 0.086). Median progression-free survival was 5.53 months for HER2-positive patients versus 1.81 months for HER2-negative patients (p = 0.037). Pembrolizumab as a salvage chemotherapy for the treatment of AGC demonstrated superior effectiveness in HER2-positive patients compared with HER2-negative patients.

Resistance to Anti-HER2 Therapies in Gastrointestinal Malignancies

Human epidermal growth factor 2 (HER2) is a tyrosine kinase receptor that interacts with multiple signaling pathways related to cellular growth and proliferation. Overexpression or amplification of HER2 is linked to various malignancies, and there have been decades of research dedicated to targeting HER2. Despite the landmark ToGA trial, progress in HER2-positive gastrointestinal malignancies has been hampered by drug resistance. This review examines current HER2 expression patterns and therapies for gastroesophageal, colorectal, biliary tract, and small bowel cancers, while dissecting potential resistance mechanisms that limit treatment effectiveness.

HER-2 positive gastric cancer: Current targeted treatments

Gastric cancer (GC) is highly metastatic and characterized by HER2 amplification. Aberrant HER2 expression drives metastasis, therapy resistance, and tumor recurrence. HER2 amplification contributes to drug resistance by upregulating DNA repair enzymes and drug afflux proteins, reducing drug efficacy. HER2 modulates transcription factors critical for cancer stem cell properties, further impacting drug resistance. HER2 activity is influenced by HER-family ligands, promoting oncogenic signaling. These features point to HER2 as a targetable driver in GC. This review outlines recent advances in HER2-mediated mechanisms and their upstream and downstream signaling pathways in GC. Additionally, it discusses preclinical research investigation that comprehends trastuzumab-sensitizing phytochemicals, chemotherapeutics, and nanoparticles as adjunct therapies. These developments hold promise for improving outcomes and enhancing the management of HER2-positive GC.

[What's new in gastric cancer?]

In the locally advanced stage, multimodal therapies such as perioperative chemotherapy with FLOT or neoadjuvant radiochemotherapy are recommended. The integration of immunotherapy into these concepts could improve the prognosis. Phase II/III trials such as DANTE, KEYNOTE-585 and MATTERHORN show promising results in terms of pathological remissions but data on survival time extension for unselected patients are so far sobering. Immunotherapies and new targeted therapies offer hope in the palliative treatment of metastatic gastric cancer. Studies such as CheckMate-649 and KEYNOTE-859 show an improvement in survival and response rates. Currently, both pembrolizumab and nivolumab have been approved for the first-line treatment of tumors with positive PD-L1 expression. In HER2-positive tumors, the KEYNOTE-811 study showed that patients benefit from combination therapies with immune checkpoint inhibition and anti-HER2 therapies. The antibody-drug conjugate trastuzumab-deruxtecan is a promising second-line treatment option for HER2-positive tumors after treatment failure with trastuzumab.In addition, the bispecific antibody zanidatamab shows promising results in first-line treatment. New targeted therapies against CLDN18.2 and FGFR2b are showing promising results. The anti-claudin 18.2 (CLDN18.2) antibody zolbetuximab leads to improved survival compared to chemotherapy alone in patients with CLDN18.2 positive disease in first-line therapy, with approval expected in 2024.

Landscape of clinical drug development of ADCs used for the pharmacotherapy of cancers: an overview of clinical trial registry data from 2002 to 2022

BACKGROUND

To provide reference for clinical development of ADCs in the industry, we analyzed the landscape and characteristics of clinical trials about antibody-drug conjugates (ADCs).

METHOD

Clinical trials to study ADCs used for the pharmacotherapy of cancers initiated by the sponsor were searched in the Cite line Pharma Intelligence (Trialtrove database), and the landscape and characteristics of these clinical trials were analyzed from multiple perspectives, such as the number, phases, status, indications, and targets of the clinical trials.

RESULT

As of December 31, 2022, a total of 431 clinical trials have been initiated to study ADCs used for the pharmacotherapy of cancers, and the number of the last 10 years was 5.5 times as large as the first 11 years. These clinical trials involved 47 indications, including breast cancer, lymphoma (lymphoma, non-Hodgkin's and lymphoma, Hodgkin's), unspecified solid tumor, bladder cancer and lung cancer (lung, non-small cell cancer and lung, small cell cancer). As for each of these five indications, 50 + clinical trials have been carried out, accounting for as high as 48.50% (454/936). ADCs involve 38 targets, which are relatively concentrated. Among them, ERBB2 (HER2) and TNFRSF8 (CD30) involve in 100 + registered clinical trials, and TNFRSF17 (BCMA), NECTIN4 and CD19 in 10 + trials. The clinical trials for these five targets account for 79.02% (354/448) of the total number. Up to 93.97% (405/431) of these clinical trials explored the correlation between biomarkers and efficacy. Up to 45.91% (292/636) of Lots (lines of treatment) applied in the clinical trials were the second line. Until December 31, 2022, 54.52% (235/431) of the clinical trials have been completed or terminated.

CONCLUSION

ADCs are a hotspot of research and development in oncology clinical trials, but the indications, targets, phases, and Lot that have been registered are seemingly relatively concentrated at present. This study provides a comprehensive analysis which can assist researchers/developer quickly grasp relevant knowledge to assess a product and also providing new clues and ideas for future research.

Biomarker-oriented chemo-immunotherapy for advanced gastric cancer

The biomarker-oriented chemo-immunotherapy is useful and promising in the development of new anticancer agents, since the responders can be enriched by selecting patients with biomarkers. Compared to colorectal and lung cancers, the development of biomarker-driven molecular-targeted therapeutics for gastric cancers has been straggled. However, several new biomarkers in gastric cancers have been discovered and clinical trials in enrichment design with certain biomarkers have been conducted. Therefore, there are currently several treatment options to treat gastric cancer patients based on individual biomarker-oriented strategies. In the present review, we describe the useful biomarkers in gastric cancer, with focusing on HER2, PD-L1, and Claudin18.2, in relation to their clinical significance and associated targeted agents.

State of the art and upcoming trends in HER2-directed therapies in gastrointestinal malignancies

PURPOSE OF REVIEW

This review critically evaluates the evolution and current status of human epidermal growth factor receptor 2 (HER2)-directed therapies in upper gastrointestinal (GI) malignancies, a timely and relevant inquiry given the dynamic shifts in therapeutic strategies over the past decade. Initial enthusiasm following the Trastuzumab for Gastric Cancer (ToGA) study's demonstration of trastuzumab's efficacy, however, encountered hurdles due to subsequent trials showing limited progress, underscoring the necessity for a reevaluation of therapeutic approaches and the exploration of novel agents.

RECENT FINDINGS

The review highlights significant breakthroughs in the form of immune checkpoint inhibitors and innovative therapeutic technologies, which have redefined treatment paradigms and shown promising efficacy in HER2-positive cases. Emerging treatments such as trastuzumab deruxtecan (T-DXd), zanidatamab and evorpacept further illustrate the ongoing efforts to leverage unique mechanisms of action for improved HER2-positive antitumor activity.

SUMMARY

The advancements in HER2-directed therapies underscore a pivotal era in the management of upper GI malignancies. These developments not only reflect the profound impact of integrating novel therapeutic combinations but also highlight the critical role of ongoing research in overcoming resistance mechanisms and tailoring treatment to individual disease profiles.

Drug Delivery Opportunities in Esophageal Cancer: Current Treatments and Future Prospects

With one of the highest mortality rates of all malignancies, the 5-year survival rate for esophageal cancer is under 20%. Depending on the stage and extent of the disease, the current standard of care treatment paradigm includes chemotherapy or chemoradiotherapy followed by surgical esophagogastrectomy, with consideration for adjuvant immunotherapy for residual disease. This regimen has high morbidity, due to anatomic changes inherent in surgery, the acuity of surgical complications, and off-target effects of systemic chemotherapy and immunotherapy. We begin with a review of current treatments, then discuss new and emerging targets for therapies and advanced drug delivery systems. Recent and ongoing preclinical and early clinical studies are evaluating traditional tumor targets (e.g., human epidermal growth factor receptor 2), as well as promising new targets such as Yes-associated protein 1 or mammalian target of rapamycin to develop new treatments for this disease. Due the function and location of the esophagus, opportunities also exist to pair these treatments with a drug delivery strategy to increase tumor targeting, bioavailability, and intratumor concentrations, with the two most common delivery platforms being stents and nanoparticles. Finally, early results with antibody drug conjugates and chimeric antigenic receptor T cells show promise as upcoming therapies. This review discusses these innovations in therapeutics and drug delivery in the context of their successes and failures, with the goal of identifying those solutions that demonstrate the most promise to shift the paradigm in treating this deadly disease.

Antibody-drug conjugates combinations in cancer treatment

Antibody-drug conjugates (ADCs) have emerged as a promising class of anticancer agents. Currently, the Food and Drug Administration has granted approval to 12 compounds, with 2 later undergoing withdrawal. Moreover, several other compounds are currently under clinical development at different stages. Despite substantial antitumoral activity observed among different tumor types, adverse events and the development of resistance represent significant challenges in their use. Over the last years, an increasing number of clinical trials have been testing these drugs in different combinations with other anticancer agents, such as traditional chemotherapy, immune checkpoint inhibitors, monoclonal antibodies, and small targeted agents, reporting promising results based on possible synergistic effects and a potential for improved treatment outcomes among different tumor types. Here we will review combinations of ADCs with other antitumor agents aiming at describing the current state of the art and future directions.

Progress and prospects of biomarker-based targeted therapy and immune checkpoint inhibitors in advanced gastric cancer

Gastric cancer and gastroesophageal junction cancer represent the leading cause of tumor-related death worldwide. Although advances in immunotherapy and molecular targeted therapy have expanded treatment options, they have not significantly altered the prognosis for patients with unresectable or metastatic gastric cancer. A minority of patients, particularly those with PD-L1-positive, HER-2-positive, or MSI-high tumors, may benefit more from immune checkpoint inhibitors and/or HER-2-directed therapies in advanced stages. However, for those lacking specific targets and unique molecular features, conventional chemotherapy remains the only recommended effective and durable regimen. In this review, we summarize the roles of various signaling pathways and further investigate the available targets. Then, the current results of phase II/III clinical trials in advanced gastric cancer, along with the superiorities and limitations of the existing biomarkers, are specifically discussed. Finally, we will offer our insights in precision treatment pattern when encountering the substantial challenges.

Molecular classification and intratumoral heterogeneity of gastric adenocarcinoma

Gastric cancers frequently harbor striking histological complexity and diversity between lesions as well as within single lesions, known as inter- and intratumoral heterogeneity, respectively. The latest World Health Organization Classification of Tumors designated more than 30 histological subtypes for gastric epithelial tumors, assigning 12 subtypes for gastric adenocarcinoma (GAD). Meanwhile, recent advances in genome-wide analyses have provided molecular aspects to the histological classification of GAD, and consequently revealed different molecular traits underlying these histological subtypes. Moreover, accumulating knowledge of comprehensive molecular profiles has led to establishing molecular classifications of GAD, which are often associated with clinical biomarkers for therapeutics and prognosis. However, most of our knowledge of GAD molecular profiles is based on inter-tumoral heterogeneity, and the molecular profiles underlying intratumoral heterogeneity are yet to be determined. In this review, recently established molecular classifications of GAD are introduced in the aspect of pathological diagnosis and are discussed in the context of intratumoral heterogeneity.

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.

Incorporating Molecular Data Into Treatment Decision Making in Gastroesophageal and Pancreaticobiliary Cancers: Timing and Strategies

Gastroesophageal (GE) and pancreatobiliary (PB) cancers represent a significant clinical challenge. In this context, it is critical to understand the key molecular targets within these malignancies including how they are assayed for as well as the clinical actionability of these targets. Integrating biomarkers into the standard of care presents a critical avenue for refining treatment paradigms. This review aims to explore these complexities, offering insights into the optimal sequencing of chemotherapy and targeted therapies and their utility in the management of GE and PB cancers. The timely integration of promising investigational therapies into clinical practice has broader implications around strategies for future clinical trial designs, which would pave the way for advancements in the management of GE and PB cancers. This review provides guidance in navigating the evolving landscape of GE and PB cancer care, which ultimately will drive forward progress in the field and lead to improved patient outcomes.

Advances in Human Epidermal Growth Factor Receptor 2-Targeted Therapy in Upper Gastrointestinal Cancers

The Trastuzumab for Gastric Cancer (ToGA) trial marked a pivotal moment in the adoption of trastuzumab for treating advanced human epidermal growth factor receptor 2 (HER2)-positive esophagogastric (EG) cancer. The KEYNOTE-811 trial brought to light the synergistic effect of immune modulation and HER2 targeting. Additionally, the emergence of trastuzumab deruxtecan (T-DXd) highlighted the potential of new pharmaceutical technologies to extend response, particularly for patients who have advanced beyond initial HER2-targeted therapies. This review aims to navigate through both the successes and challenges encountered historically, as well as promising current trials on innovative and transformative therapeutic strategies, including promising first-in-class and novel first-in-human agents.

Immunotherapy and targeted therapy as first-line treatment for advanced gastric cancer

For patients diagnosed with advanced gastric or gastroesophageal cancer that is not amenable to surgical intervention, the standard of care for first-line treatment consists of fluoropyrimidine and platinum-based chemotherapy. The incorporation of novel agents into these standard first-line regimens could potentially improve patient prognosis; options for such augmentations include both immune-based and targeted therapy combinations. To provide a comparative analysis of these different first-line combination treatments, a network meta-analysis was conducted. Outcome measures comprised overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and grade 3-4 treatment-related adverse events (TRAEs). Data were drawn from 22 randomized controlled trials, encompassing 10,787 patients and 17 distinct treatment regimens. Our findings suggest that FGFR2b-targeted therapy, specifically when used in combination with chemotherapy (bemarituzumab_chemo), exhibited the greatest efficacy. This was followed by immunotherapy-based combination regimens (CPS ≥5, Sintilimab_chemo). Further, targeted combination therapy featuring CLAUDIN 18.2 (zolbetuximab_chemo) appeared beneficial based on individual patient characteristics. In the case of HER2-positive patients, the trastuzumab_chemo regimen is recommended, as most existing studies have excluded this subpopulation. These results have significant implications for both clinical decision-making and patient care in the realm of advanced gastric or gastroesophageal cancer treatment.