FGFR2 amplification has prognostic significance in gastric cancer: results from a large international multicentre study

Phase 2 study of futibatinib in patients with gastric or gastroesophageal junction cancer harboring FGFR2 amplifications

BACKGROUND AND AIMS

Aberrant fibroblast growth factor receptor (FGFR)-driven signaling, predominantly arising from FGFR2 amplification, plays a key role in gastric cancer pathogenesis. This open-label, phase 2 study evaluated the efficacy and safety of futibatinib, an irreversible FGFR1-4 inhibitor, in patients with gastric or gastroesophageal junction (GEJ) cancer harboring FGFR2 amplifications.

METHODS

Patients were treated with futibatinib 20 mg orally once daily in a 28-day cycle. The primary endpoint was objective response rate (ORR) per independent central review. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and safety.

RESULTS

Among 28 treated patients, the ORR per independent central review was 17.9 %, comprising five patients with a partial response (median duration of response, 3.9 months), and an additional nine patients with stable disease for a disease control rate of 50.0 %. Median PFS per independent central review and median OS were 2.9 and 5.9 months, respectively. The most common treatment-related adverse events (any grade) were hyperphosphatemia (89.3 %), decreased appetite (32.1 %), and increased aspartate aminotransferase (21.4 %). Only one (3.6 %) patient discontinued study treatment due to an adverse event. Futibatinib demonstrated modest antitumor activity with a safety profile consistent with previous reports in patients with gastric or GEJ cancer harboring FGFR2 amplifications, potentially warranting further investigation.

Pharmacokinetics of infigratinib and its active metabolites in Chinese patients with advanced gastric cancer harboring FGFR2 gene amplification

Infigratinib, an FGFR1-3 selective oral tyrosine kinase inhibitor, has shown clinical activity in cancers with FGFR alterations. The pharmacokinetics (PK) of infigratinib and its major metabolites have been characterized in global populations. This study examined the PK profile of infigratinib and its metabolites in Chinese patients. In this phase II, open-label, single-arm study in China, patients with advanced gastric cancer (GC) or gastroesophageal junction adenocarcinoma (GEJ) harboring FGFR2 gene amplification received 125 mg infigratinib orally once daily in a "3 weeks on, 1 week off" schedule for 28-day cycles. Plasma PK parameters were calculated with a non-compartmental model. Data were available from 21 patients (19 GC and two GEJ). After a single dose, peak infigratinib plasma concentration was reached at a median time of 3.1 h, with geometric mean Cmax of 85.9 ng/mL and AUC0-t of 637 h*ng/mL. After 21-day dosing, geometric mean infigratinib Cmax,ss of 204 ng/mL was reached at a median of 4.0 h; geometric mean AUC0-24,ss was 3060 h*ng/mL. The geometric mean Rac,Cmax (%CV) and Rac,AUC0-24 (%CV) of infigratinib was 2.5 (113.8) and 5.1 (138.2), respectively. A steady state of infigratinib was reached after continuous dosing for 15 days. The metabolites accounting for >10% of infigratinib were BHS697 and CQM157. The PK profiles of infigratinib and its metabolites in Chinese patients with GC or GEJ were largely consistent with known PK profiles of infigratinib from global populations.

Diffuse Gastric Cancer: A Comprehensive Review of Molecular Features and Emerging Therapeutics

Diffuse-type gastric cancer (DGC) accounts for approximately one-third of gastric cancer diagnoses but is a more clinically aggressive disease with peritoneal metastases and inferior survival compared with intestinal-type gastric cancer (IGC). The understanding of the pathogenesis of DGC has been relatively limited until recently. Multiomic studies, particularly by The Cancer Genome Atlas, have better characterized gastric adenocarcinoma into molecular subtypes. DGC has unique molecular features, including alterations in CDH1, RHOA, and CLDN18-ARHGAP26 fusions. Preclinical models of DGC characterized by these molecular alterations have generated insight into mechanisms of pathogenesis and signaling pathway abnormalities. The currently approved therapies for treatment of gastric cancer generally provide less clinical benefit in patients with DGC. Based on recent phase II/III clinical trials, there is excitement surrounding Claudin 18.2-based and FGFR2b-directed therapies, which capitalize on unique biomarkers that are enriched in the DGC populations. There are numerous therapies targeting Claudin 18.2 and FGFR2b in various stages of preclinical and clinical development. Additionally, there have been preclinical advancements in exploiting unique therapeutic vulnerabilities in several models of DGC through targeting of the focal adhesion kinase (FAK) and Hippo pathways. These preclinical and clinical advancements represent a promising future for the treatment of DGC.

Overexpression of Fibroblast Growth Factor 8 Is a Predictor of Impaired Survival in Esophageal Squamous Cell Carcinoma and Correlates with ALK/EML4 Alteration

FGF8, ALK, and EML4 have been identified as promising biomarkers in a number of malignancies. The aim of this study was to examine the prognostic role of FGF8, ALK, and EML4 in esophageal squamous cell carcinoma (ESCC). Methods: Consecutive patients with ESCC who underwent upfront resection were included in this study. ALK and EML4 gene status was evaluated by fluorescence in situ hybridization (FISH) using a triple-color break-apart single-fusion probe and a probe against 2p11. FGF8, ALK, and EML4 protein expression was determined by immunohistochemistry. Results: A total of 122 patients were included in this study. Multivariate analysis revealed that FGF8 overexpression is an independent negative prognostic factor for patients' overall survival (OS) (p = 0.04). Furthermore, a significant correlation between the expression of FGF8, and ALK (p = 0.04) and EML4 (p = 0.01) alteration was found. Conclusions: FGF8 overexpression is an adverse independent prognostic factor in patients with upfront resected ESCC. Furthermore, FGF8 expression significantly correlates with ALK and EML4 amplification and may therefore qualify as a future therapeutic target.

New therapeutic target molecules for gastric and gastroesophageal junction cancer

Molecularly targeted therapy for receptor tyrosine kinases (RTKs) has faced limitations in gastric and gastroesophageal junction (G/GEJ) cancer except for HER2-targeted agents, possibly due to inappropriate assay selection that has hindered identification of sensitive patients, in addition to coexisting genetic abnormalities as well as intratumoral heterogeneity. Immunohistochemistry of RTKs has, thus, proved largely unsuccessful for patient selection, and detection of RTK gene amplification as a true oncogenic driver is problematic given the small numbers of affected individuals. FGFR2 amplification is associated with poor prognosis in G/GEJ cancer, and immunohistochemistry of the FGFR2b protein isoform has proved effective for the detection of such FGFR2-dependent tumors. Phase III and Ib/III trials of the FGFR2-targeted antibody bemarituzumab for G/GEJ cancer overexpressing FGFR2b are ongoing based on the promising result in a phase II trial, especially in cases with an FGFR2b positivity of ≥ 10%. Challenges to EGFR- and MET-targeted therapies are being tackled with antibody-drug conjugates (ADCs) and bispecific antibodies. CLDN18.2 is expressed in some G/GEJ tumors but lacks oncogenic driver potential, and the CLDN18.2-targeted antibody zolbetuximab prolonged the survival of CLDN18.2-positive G/GEJ cancer patients in phase III trials. Antibody-drug conjugates and ADCs that target CLDN18.2 are also being pursued for treatment of such patients. Similarly, targeting of nondriver molecules such as DKK1, TROP2, and CEACAM5 is under investigation in early-stage clinical trials. This shift in focus from target molecules with driver potential to markers for precise drug delivery should increase the number of possible targets in G/GEJ cancer.

Pembrolizumab in combination with trastuzumab for treatment of HER2-positive advanced gastric or gastro-esophageal junction cancer

Introduction

Gastric cancer remains a challenging malignancy with a high global mortality rate. Recent advances in targeted therapy and immunotherapy have shown promise in improving patient outcomes. This paper reviews the impact of incorporating targeted agents such as trastuzumab and immunotherapeutic agents like pembrolizumab into standard chemotherapy regimens for gastric cancer treatment.

Methods

A comprehensive analysis was conducted on pivotal clinical trials, including KEYNOTE-590, KEYNOTE-811, and ToGA, focusing on their methodologies, patient populations, treatment regimens, and outcome measures. The review also explored emerging research avenues in precision medicine, particularly genomic sequencing and biomarker identification.

Aim

To assess the efficacy and survival benefits of adding trastuzumab and pembrolizumab to standard chemotherapy in the treatment of gastric cancer and to outline future directions in gastric cancer research.

Results

Including trastuzumab and pembrolizumab in treatment regimens for human epidermal growth factor receptor 2 (HER2)-positive and PD-L1-expressing gastric cancers significantly improved progression-free and overall survival rates compared to chemotherapy alone. These findings highlight the potential of personalized therapy in enhancing treatment outcomes. Furthermore, ongoing research into the gastric cancer microenvironment and the role of the microbiome suggests novel targets for future therapeutic interventions.

Conclusion

The integration of targeted and immunotherapeutic agents with traditional chemotherapy represents a pivotal shift in gastric cancer treatment, moving towards more personalized and effective regimens.

Deciphering the FGFR2 Code: Innovative Targets in Gastric Cancer Therapy

Gastric cancer (GC) represents a major global health challenge as a highly prevalent disease with high mortality whose global incidence and mortality are predicted to worsen over the coming years. To date, our standard of care for advanced gastric cancer of combination chemotherapy and immunotherapy has a 1-year overall survival rate of 55%. Significant efforts have gone into identifying targetable alterations in gastric cancer, ultimately yielding the Fibroblast Growth Factor Receptors (FGFRs) family, specifically FGFR2 as a promising target. FGFR2 is overexpressed in GC, particularly diffuse-type GC, and is associated with poor prognostic outcomes. In recent years, there has been an increasing number of small molecule inhibitors and monoclonal antibodies targeting FGFR2 that have entered into clinical trials. Specifically for GC, these agents are currently being trialed in various phases as monotherapies or with standard-of-care treatments to make a clinically meaningful impact on what appears to be an important biological axis of GC. In this review, we outline the underlying biology of FGFR2, its putative role in GC, and the various FGFR2-targeted agents currently in clinical trials for gastric cancer patients as well as postulate some challenges in adopting these therapeutics for clinically meaningful benefit.

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.

Genomic and Pathologic Profiling of Very Well-Differentiated Gastric Adenocarcinoma of Intestinal Type: A Study With Emphasis on Diffuse-Type Transformation

Very well-differentiated adenocarcinoma of intestinal type is a distinct subtype of gastric cancer characterized by anastomosing glands with a hand-in-hand pattern and low-grade cytologic atypia resembling intestinal metaplasia. This is a slow-growing neoplasm with an indolent clinical course; however, a subset demonstrates transformation into adenocarcinoma with higher-grade histology, typically diffuse-type carcinoma, and behaves aggressively. This study aimed to better characterize the genomic and pathologic features, with a focus on factors associated with diffuse-type transformation. A total of 58 cases with (n=31) and without (n=27) diffuse-type transformation were analyzed for molecular and pathologic features. First, comprehensive deep DNA sequencing was conducted in 18 cases (discovery cohort), followed by a digital droplet polymerase chain reaction of hot spot RHOA mutations in 40 cases (validation cohort). In total, RHOA mutations were the most common alteration (34%), followed by loss of ARID1A (12%), p53 alterations (10%), and CLDN18 :: ARHGAP26/6 fusions (3.4%). FGFR2 amplification was identified in an advanced case with a p53 alteration. Altered p53 expression was recognized only in higher-grade components and was significantly associated with advanced disease ( P =0.0015) and diffuse-type transformation ( P =0.026). A mixed mucin phenotype was also strongly correlated with advanced disease ( P <0.001) and diffuse-type transformation ( P <0.001). Decreased E-cadherin expression was frequently observed (74%) in poorly cohesive components. This study demonstrated that a subset of RHOA -mutant diffuse-type gastric cancers develops through the transformation of very well-differentiated adenocarcinoma of intestinal type. Our observations suggest a mixed mucin phenotype as a risk factor and alterations in p53 and E-cadherin as drivers of diffuse-type transformation.

Clinical Developments and Challenges in Treating FGFR2-Driven Gastric Cancer

Recent advances in the treatment of gastric cancer (GC) with chemotherapy, immunotherapy, anti-angiogenic therapy and targeted therapies have yielded some improvement in survival outcomes; however, metastatic GC remains a lethal malignancy and amongst the leading causes of cancer-related mortality worldwide. Importantly, the ongoing molecular characterisation of GCs continues to uncover potentially actionable molecular targets. Among these, aberrant FGFR2-driven signalling, predominantly arising from FGFR2 amplification, occurs in approximately 3-11% of GCs. However, whilst several inhibitors of FGFR have been clinically tested to-date, there are currently no approved FGFR-directed therapies for GC. In this review, we summarise the significance of FGFR2 as an actionable therapeutic target in GC, examine the recent pre-clinical and clinical data supporting the use of small-molecule inhibitors, antibody-based therapies, as well as novel approaches such as proteolysis-targeting chimeras (PROTACs) for targeting FGFR2 in these tumours, and discuss the ongoing challenges and opportunities associated with their clinical development.

Molecular Targeting of the Fibroblast Growth Factor Receptor Pathway across Various Cancers

Fibroblast growth factor receptors (FGFRs) are a family of receptor tyrosine kinases that are involved in the regulation of cell proliferation, survival, and development. FGFR alterations including amplifications, fusions, rearrangements, and mutations can result in the downstream activation of tyrosine kinases, leading to tumor development. Targeting these FGFR alterations has shown to be effective in treating cholangiocarcinoma, urothelial carcinoma, and myeloid/lymphoid neoplasms, and there are currently four FGFR inhibitors approved by the Food and Drug Administration (FDA). There have been developments in multiple agents targeting the FGFR pathway, including selective FGFR inhibitors, ligand traps, monoclonal antibodies, and antibody-drug conjugates. However, most of these agents have variable and low responses, with some intolerable toxicities and acquired resistances. This review will summarize previous clinical experiences and current developments in agents targeting the FGFR pathway, and will also discuss future directions for FGFR-targeting agents.

Emerging Targets for Systemic Treatment of Gastric Cancer: HER2 and Beyond

In recent years, remarkable progress has been made in the molecular profiling of gastric cancer. This progress has led to the development of various molecular classifications to uncover subtype-specific dependencies that can be targeted for therapeutic interventions. Human epidermal growth factor receptor 2 (HER2) is a crucial biomarker for advanced gastric cancer. The recent promising results of novel approaches, including combination therapies or newer potent agents such as antibody-drug conjugates, have once again brought attention to anti-HER2 targeted treatments. In HER2-negative diseases, the combination of cytotoxic chemotherapy and programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) inhibitors has become the established standard of care in first-line settings. In the context of gastric cancer, potential biomarkers such as PD-L1 expression, Epstein-Barr virus, microsatellite instability, and tumor mutational burden are being considered for immunotherapy. Recently, promising results have been reported in studies on anti-Claudin18.2 and fibroblast growth factor receptor 2 treatments. Currently, many ongoing trials are aimed at identifying potential targets using novel approaches. Further investigations will be conducted to enhance the progress of these therapies, addressing challenges such as primary and acquired resistance, tumor heterogeneity, and clonal evolution. We believe that these efforts will improve patient prognoses. Herein, we discuss the current evidence of potential targets for systemic treatment, clinical considerations, and future perspectives.

Futibatinib, an Irreversible FGFR1-4 Inhibitor for the Treatment of FGFR-Aberrant Tumors

Fibroblast growth factor receptors (FGFR) are emerging as an important therapeutic target for patients with advanced, refractory cancers. Most selective FGFR inhibitors under investigation show reversible binding, and their activity is limited by acquired drug resistance. This review summarizes the preclinical and clinical development of futibatinib, an irreversible FGFR1-4 inhibitor. Futibatinib stands out among FGFR inhibitors because of its covalent binding mechanism and low susceptibility to acquired resistance. Preclinical data indicated robust activity of futibatinib against acquired resistance mutations in the FGFR kinase domain. In early-phase studies, futibatinib showed activity in cholangiocarcinoma, and gastric, urothelial, breast, central nervous system, and head and neck cancers harboring various FGFR aberrations. Exploratory analyses indicated clinical benefit with futibatinib after prior FGFR inhibitor use. In a pivotal phase II trial, futibatinib demonstrated durable objective responses (42% objective response rate) and tolerability in previously treated patients with advanced intrahepatic cholangiocarcinoma harboring FGFR2 fusions or rearrangements. A manageable safety profile was observed across studies, and patient quality of life was maintained with futibatinib treatment in patients with cholangiocarcinoma. Hyperphosphatemia, the most common adverse event with futibatinib, was well managed and did not lead to treatment discontinuation. These data show clinically meaningful benefit with futibatinib in FGFR2-rearrangement-positive cholangiocarcinoma and provide support for further investigation of futibatinib across other indications. Future directions for this agent include elucidating mechanisms of resistance and exploration of combination therapy approaches.

Lysine-specific demethylase 7A (KDM7A): A potential target for disease therapy

Histone demethylation is a kind of epigenetic modification mediated by a variety of enzymes and participates in regulating multiple physiological and pathological events. Lysine-specific demethylase 7A is a kind of α-ketoglutarate- and Fe(II)-dependent demethylase belonging to the PHF2/8 subfamily of the JmjC demethylases. KDM7A is mainly localized in the nucleus and contributes to transcriptional activation via removing mono- and di-methyl groups from the lysine residues 9 and 27 of Histone H3. Mounting studies support that KDM7A is not only necessary for normal embryonic, neural, and skeletal development, but also associated with cancer, inflammation, osteoporosis, and other diseases. Herein, the structure of KDM7A is described by comparing the similarities and differences of its amino acid sequences of KDM7A and other Histone demethylases; the functions of KDM7A in homeostasis and dyshomeostasis are summarized via documenting its content and related signaling; the currently known KDM7A-specific inhibitors and their structural relationship are listed based on their structure optimization and pharmacological activities; and the challenges and opportunities in exploring functions and developing targeted agents of KDM7A are also prospected via presenting encountered problems and potential solutions, which will provide an insight in functional exploration and drug discovery for KDM7A-related diseases.

Novel Biomarkers of Gastric Cancer: Current Research and Future Perspectives

Gastric cancer is a heterogeneous disease with diverse histological and genomic subtypes, making it difficult to demonstrate treatment efficacy in clinical trials. However, recent efforts have been made to identify molecular biomarkers with prognostic and predictive implications to better understand the broad heterogeneity of gastric cancer and develop effective targeted therapies for it. HER2 overexpression, HER2/neu amplification, MSI-H, and PD-L1+ are predictive biomarkers in gastric cancer, and a growing number of clinical trials based on novel biomarkers have demonstrated the efficacy of targeted therapies alone or in combination with conventional chemotherapy. Enrichment design clinical trials of targeted therapies against FGFR2b and claudin 18.2 have demonstrated efficacy in unresectable advanced gastric cancer. Nonetheless, it is essential to continuously validate promising molecular biomarkers and introduce them into clinical practice to optimize treatment selection and improve patient outcomes. In this review, we focused on established (PD-L1, HER2, MSI) and emerging biomarkers (FGFR2, CLDN18.2) in gastric cancer, their clinical significance, detection methods, limitations, and molecular agents that target these biomarkers.

Detection of a Novel MSI2-C17orf64 Transcript in a Patient with Aggressive Adenocarcinoma of the Gastroesophageal Junction: A Case Report

Adenocarcinoma of the esophagus (EAC) and gastroesophageal junction (GEJ-AC) is associated with poor prognosis, treatment resistance and limited systemic therapeutic options. To deeply understand the genomic landscape of this cancer type, and potentially identify a therapeutic target in a neoadjuvant chemotherapy non-responder 48-year-old man, we adopted a multi-omic approach. We simultaneously evaluated gene rearrangements, mutations, copy number status, microsatellite instability and tumor mutation burden. The patient displayed pathogenic mutations of the TP53 and ATM genes and variants of uncertain significance of three kinases genes (ERBB3, CSNK1A1 and RPS6KB2), along with FGFR2 and KRAS high copy number amplification. Interestingly, transcriptomic analysis revealed the Musashi-2 (MSI2)-C17orf64 fusion that has never been reported before. Rearrangements of the RNA-binding protein MSI2 with a number of partner genes have been described across solid and hematological tumors. MSI2 regulates several biological processes involved in cancer initiation, development and resistance to treatment, and deserves further investigation as a potential therapeutic target. In conclusion, our extensive genomic characterization of a gastroesophageal tumor refractory to all therapeutic approaches led to the discovery of the MSI2-C17orf64 fusion. The results underlie the importance of deep molecular analyses enabling the identification of novel patient-specific markers to be monitored during therapy or even targeted at disease evolution.

Updated Immunotherapy for Gastric Cancer

Gastric cancer treatments are evolving rapidly. For example, immune checkpoint inhibitors, especially those that target PD-1 or PD-L1, have long-term efficacy in a subset of gastric cancer patients, and are currently the first-line therapy. Immunotherapies approved for use in untreated gastric cancer patients include monotherapy and chemotherapy-immunotherapy combinations. Major clinical trials have reported efficacy and safety data suggesting that PD-L1 expression is important for regimen selection, although other biomarkers, clinicopathologic factors, and patient preference might also be relevant in other situations. Currently, several novel biomarkers and therapeutic strategies are being assessed, which might refine the current treatment paradigm. In this review, we describe the current treatment regimens for patients with gastric cancer and detail the approach we use for the selection of first-line immunotherapy regimens.

Current molecular biomarkers evaluation in gastric/gastroesophageal junction adenocarcinoma: pathologist does matter

The comprehensive molecular characterization of gastric and gastroesophageal junction adenocarcinomas has led to the improvement of targeted and more effective treatments. As a result, several biomarkers have been introduced into clinical practice and the implementation of innovative diagnostic tools is under study. Such assessments are mainly based on the evaluation of limited biopsy material in clinical practice. In this setting, the pathologist represents a key player in the selection of patients facilitating precision medicine approaches.

Predictive biomarkers in gastric cancer

Predictive biomarkers are the mainstay of precision medicine. This review summarizes the advancements in tissue-based diagnostic biomarkers for gastric cancer, which is considered the leading cause of cancer-related deaths worldwide. A disease seen in the elderly, it is often diagnosed at an advanced stage, thereby limiting therapeutic options. In Western countries, neoadjuvant/perioperative (radio-)chemotherapy is administered, and adjuvant chemotherapy is administered in the East. The morpho-molecular classification of gastric cancer has opened novel avenues identifying Epstein-Barr-Virus (EBV)-positive, microsatellite instable, genomically stable and chromosomal instable gastric cancers. In chromosomal instable tumors, receptor tyrosine kinases (RKTs) (e.g., EGFR, FGFR2, HER2, and MET) are frequently overexpressed. Gastric cancers such as microsatellite instable and EBV-positive types often express immune checkpoint molecules, such as PD-L1 and VISTA. Genomically stable tumors show alterations in claudin 18.2. Next-generation sequencing is increasingly being used to search for druggable targets in advanced palliative settings. However, most tissue-based biomarkers of gastric cancer carry the risk of a sampling error due to intratumoral heterogeneity, and adequate tissue sampling is of paramount importance.

Analysis of Staged Features of Gastritis-Cancer Transformation and Identification of Potential Biomarkers in Gastric Cancer

Purpose

This work aims to elucidate the staged characteristics during gastritis-cancer transformation based on the transcriptome and use bioinformatics to identify potential biomarkers.

Patients and Methods

We collected blood samples from healthy controls, patients with non-atrophic gastritis, atrophic gastritis, and gastric cancer, and tissue samples from patients with gastric cancer, respectively. RNA-seq was then performed. Differentially expressed genes, weighted gene co-expression network analysis and functional enrichment analysis were used to illustrate the staged characteristics of gastritis-cancer transformation. Genes with diagnostic potential were further identified in combination with ROC analysis. Additionally, for the gastric cancer stage, the gene expression of the collected tissue transcriptome was validated using the Cancer Genome Atlas and combined with survival analysis to identify potential biomarkers.

Results

The 279 overlapping genes among the differentially expressed genes of NAG, AG and CA indicated that the expression characteristics of different stages were different. However, the 2243 overlapping genes of differential genes between adjacent stages indicated a certain consistency in the expression characteristics of stage development. The core functions of different stages have strong stage specificity and basically have no similarities. Twenty genes with diagnostic potential for AG or CA were obtained, respectively, and no gene could effectively differentiate NAG samples. Thirty-four potential biomarkers for gastric cancer were identified, of which 14 genes have not been reported, including ACTG2, C1QTNF2, NCAPH and SORCS1.

Conclusion

There may be a stable development mechanism in the process of gastritis-carcinoma transformation, resulting in the differences in the performance of each stage. The newly discovered staging features and potential biomarkers in this work can provide references for related research.

Bemarituzumab in patients with FGFR2b-selected gastric or gastro-oesophageal junction adenocarcinoma (FIGHT): a randomised, double-blind, placebo-controlled, phase 2 study

BACKGROUND

Outcomes are poor in patients with HER2-negative, advanced gastric or gastro-oesophageal junction adenocarcinomas. In this study, we investigated efficacy and safety of the first-in-class, afucosylated, humanised IgG1 anti-fibroblast growth factor receptor 2 isoform IIb (FGFR2b) monoclonal antibody bemarituzumab with modified 5-fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) in patients with FGFR2b-selected gastric or gastro-oesophageal junction adenocarcinoma.

METHODS

In the randomised, double-blind, placebo-controlled phase 2 trial (FIGHT), patients aged 18 years and older with HER2 non-positive, FGFR2b-selected gastric or gastro-oesophageal junction adenocarcinoma, and an Eastern Cooperative Oncology Group performance status of 0-1 were recruited from 144 clinical sites across 17 countries. Patients with previous treatment with any selective inhibitor of the FGF-FGFR pathway were excluded. Eligible patients were randomly assigned (1:1), using permuted-block randomisation (block size of four) and a central interactive voice-web-based response system, stratified by geographical region, previous treatment with curative intent, and administration of mFOLFOX6 while being screened for FGFR2b status, to either bemarituzumab (15 mg/kg of bodyweight) or matched placebo intravenously every 2 weeks. All patients also received mFOLFOX6 (oxaliplatin 85 mg/m², leucovorin 400 mg/m², and 5-fluorouracil as a 400 mg/m² bolus followed by 2400 mg/m² over approximately 46 h) intravenously every 2 weeks. Patients were given treatment until disease progression (defined by Response Evaluation Criteria in Solid Tumours [RECIST] version 1.1), unacceptable toxicity, withdrawal of consent, or death. The primary endpoint was progression-free survival in the intention-to-treat population (defined as all patients randomly assigned to treatment). Safety was assessed in all patients who received at least one dose of assigned treatment. This study is registered with ClinicalTrials.gov, NCT03694522, and is now complete.

FINDINGS

Between Nov 14, 2017, and May 8, 2020, 910 patients were screened and 155 were randomly assigned to the bemarituzumab (n=77) or placebo group (n=78). Median age was 60·0 years (IQR 51·0-67·0), 44 (28%) participants were women, 111 (72%) were men, 89 (57%) were Asian, and 61 (39%) were White. At the time of the primary analysis and at a median follow-up of 10·9 months (IQR 6·3-14·2), median progression-free survival was 9·5 months (95% CI 7·3-12·9) in the bemarituzumab group and 7·4 months (5·8-8·4) in the placebo group (hazard ratio [HR] 0·68 [95% CI 0·44-1·04; p=0·073). Common grade 3 or worse adverse events were decreased neutrophil count (23 [30%] of 76 in the bemarituzumab group vs 27 [35%] of 77 in the placebo group), cornea disorder (18 [24%] vs none), neutropenia (ten [13%] vs seven [9%]), stomatitis (seven [9%] vs one [1%]), and anaemia (six [8%] vs ten [13%]). Serious treatment-emergent adverse events were reported in 24 (32%) patients in the bemarituzumab group and 28 (36%) in the placebo group. Serious mFOLFOX6 treatment-related adverse events occurred in nine (12%) patients in the bemarituzumab group and in 15 (19%) patients in the placebo group. All-grade corneal events (adverse events of special interest) occurred in 51 (67%) patients in the bemarituzumab group and eight (10%) in the placebo group; grade 3 corneal events were reported only in 18 (24%) patients in the bemarituzumab group. Treatment-related deaths occurred in three patients in the bemarituzumab group (two due to sepsis, one due to pneumonia) and none in the placebo group.

INTERPRETATION

In this exploratory phase 2 study, despite no statistically significant improvement in progression-free survival, treatment with bemarituzumab showed promising clinical efficacy. Confirmatory phase 3 trials of bemarituzumab plus mFOLFOX6 powered to demonstrate statistical significance are being investigated in patients with previously untreated, FGFR2b-overexpressing, advanced gastric or gastro-oesophageal junction adenocarcinoma.

FUNDING

Five Prime Therapeutics.

Targeting FGFR2 Positive Gastroesophageal Cancer: Current and Clinical Developments

Despite recent advances in the systemic treatment of gastroesophageal cancers, prognosis remains poor. Comprehensive molecular analyses have characterized the genomic landscape of gastroesophageal cancer that has established therapeutic targets such as human epidermal growth factor receptor 2 (HER2), vascular endothelial growth factor receptor (VEGFR) and programmed death ligand 1 (PD-L1). The aberrant fibroblast growth factor receptor 2 (FGFR2) pathway is attractive for targetable therapy with FGFR inhibition based on preclinical data showing a pivotal role in the progression of gastric cancer (GC). FGFR2 amplification is the most common FGFR2 gene aberration in gastroesophageal cancer, and most associated with diffuse GC, which is often linked to poorer prognostic outcomes. There has been considerable progress with drug development focused on FGFR inhibition. At present, there is no approved FGFR inhibitor for FGFR2 positive gastroesophageal cancer. A selective FGFR2b monoclonal antibody bemarituzumab is currently being investigated in the first phase III randomized trial for patients with first line advanced GC, which may change the treatment paradigm for FGFR2b positive GC. The role of FGFR signalling, specifically FGFR2, is less established in oesophageal squamous cell cancer (ESCC) with a paucity of evidence for clinical benefit in these patients. Precision medicine is part of the wider approach in gastrointestinal cancers; however, it can be challenging due to heterogeneity and here circulating tumour DNA (ctDNA) for patient selection may have future clinical utility. In our review, we outline the FGFR pathway and focus on the developments and challenges of targeting FGFR2 driven gastroesophageal cancers.

Patient Selection Approaches in FGFR Inhibitor Trials-Many Paths to the Same End?

Inhibitors of fibroblast growth factor receptor (FGFR) signaling have been investigated in various human cancer diseases. Recently, the first compounds received FDA approval in biomarker-selected patient populations. Different approaches and technologies have been applied in clinical trials, ranging from protein (immunohistochemistry) to mRNA expression (e.g., RNA in situ hybridization) and to detection of various DNA alterations (e.g., copy number variations, mutations, gene fusions). We review, here, the advantages and limitations of the different technologies and discuss the importance of tissue and disease context in identifying the best predictive biomarker for FGFR targeting therapies.

Molecular Pathology of Gastric Cancer

Gastric cancer (GC) is one of the most common lethal malignant neoplasms worldwide, with limited treatment options for both locally advanced and/or metastatic conditions, resulting in a dismal prognosis. Although the widely used morphological classifications may be helpful for endoscopic or surgical treatment choices, they are still insufficient to guide precise and/or personalized therapy for individual patients. Recent advances in genomic technology and high-throughput analysis may improve the understanding of molecular pathways associated with GC pathogenesis and aid in the classification of GC at the molecular level. Advances in next-generation sequencing have enabled the identification of several genetic alterations through single experiments. Thus, understanding the driver alterations involved in gastric carcinogenesis has become increasingly important because it can aid in the discovery of potential biomarkers and therapeutic targets. In this article, we review the molecular classifications of GC, focusing on The Cancer Genome Atlas (TCGA) classification. We further describe the currently available biomarker-targeted therapies and potential biomarker-guided therapies. This review will help clinicians by providing an inclusive understanding of the molecular pathology of GC and may assist in selecting the best treatment approaches for patients with GC.

A novel small molecule RK-019 inhibits FGFR2-amplification gastric cancer cell proliferation and induces apoptosis in vitro and in vivo

Gastric cancer (GC) is one of the most malignant cancers and is estimated to be fifth in incidence ratio and the third leading cause of cancer death worldwide. Despite advances in GC treatment, poor prognosis and low survival rate necessitate the development of novel treatment options. Fibroblast growth factor receptors (FGFRs) have been suggested to be potential targets for GC treatment. In this study, we report a novel selective FGFR inhibitor, RK-019, with a pyrido [1, 2-a] pyrimidinone skeleton. In vitro, RK-019 showed excellent FGFR1-4 inhibitory activities and strong anti-proliferative effects against FGFR2-amplification (FGFR2-amp) GC cells, including SNU-16 and KATO III cells. Treatment with RK-019 suppressed phosphorylation of FGFR and its downstream pathway proteins, such as FRS2, PLCγ, AKT, and Erk, resulting in cell cycle arrest and induction of apoptosis. Furthermore, daily oral administration of RK-019 could attenuate tumor xenograft growth with no adverse effects. Here, we reported a novel specific FGFR inhibitor, RK-019, with potent anti-FGFR2-amp GC activity both in vitro and in vivo.

Mutated KLF4(K409Q) in meningioma binds STRs and activates FGF3 gene expression

Krüppel-like factor 4 (KLF4) is a transcription factor that has been proven necessary for both induction and maintenance of pluripotency and self-renewal. Whole-genome sequencing defined a unique mutation in KLF4 (KLF4K409Q) in human meningiomas. However, the molecular mechanism of this tumor-specific KLF4 mutation is unknown. Using genome-wide high-throughput and focused quantitative transcriptional approaches in human cell lines, primary meningeal cells, and meningioma tumor tissue, we found that a change in the evolutionarily conserved DNA-binding domain of KLF4 alters its DNA recognition preference, resulting in a shift in downstream transcriptional activity. In the KLF4K409Q-specific targets, the normally silent fibroblast growth factor 3 (FGF3) is activated. We demonstrated a neomorphic function of KLF4K409Q in stimulating FGF3 transcription through binding to its promoter and in using short tandem repeats (STRs) located within the locus as enhancers.

Receptor Tyrosine Kinases Amplified in Diffuse-Type Gastric Carcinoma: Potential Targeted Therapies and Novel Downstream Effectors

Simple Summary

Diffuse-type gastric carcinoma (DGC) is an aggressive subtype of gastric carcinoma with an extremely poor prognosis due to frequent peritoneal metastasis and high probability of recurrence. Its pathogenesis is poorly understood, and consequently, no effective molecular targeted therapy is available. The importance of oncogenic receptor tyrosine kinase (RTK) signaling has been recently demonstrated in the malignant progression of DGC. In particular, RTK gene amplification appears to accelerate peritoneal metastasis. In this review, we provide an overview of RTK gene amplification in DGC and the potential of related targeted therapies.

Abstract

Gastric cancer (GC) is a major cause of cancer-related death worldwide. Patients with an aggressive subtype of GC, known as diffuse-type gastric carcinoma (DGC), have extremely poor prognoses. DGC is characterized by rapid infiltrative growth, massive desmoplastic stroma, frequent peritoneal metastasis, and high probability of recurrence. These clinical features and progression patterns of DGC substantially differ from those of other GC subtypes, suggesting the existence of specific oncogenic signals. The importance of gene amplification and the resulting aberrant activation of receptor tyrosine kinase (RTK) signaling in the malignant progression of DGC is becoming apparent. Here, we review the characteristics of RTK gene amplification in DGC and its importance in peritoneal metastasis. These insights may potentially lead to new targeted therapeutics.

Design, synthesis and biological evaluation of a series of novel pyrrolo[2,3-d]pyrimidin/pyrazolo[3,4-d]pyrimidin-4-amine derivatives as FGFRs-dominant multi-target receptor tyrosine kinase inhibitors for the treatment of gastric cancer

Gastric cancer is the second most lethal cancer across the world. With the progress in therapeutic approaches, the 5-year survival rate of early gastric cancer can reach > 95%. However, the prognosis and survival time of advanced gastric cancer is still somber. Therefore, more effective targeted therapies for gastric cancer treatment are urgently needed. FGFR, VEGFR and other receptor tyrosine kinases have recently been suggested as potential targets for gastric cancer treatment. We herein report the discovery of pyrrolo[2,3-d]pyrimidin/pyrazolo[3,4-d]pyrimidin-4-amine derivatives as a new class of FGFRs-dominant multi-target receptor tyrosine kinase inhibitors. SAR assessment identified the most active compounds 8f and 8k, which showed excellent inhibitory activity against a variety of receptor tyrosine kinases. Moreover, 8f and 8k displayed excellent potency in the SNU-16 gastric cancer cell line. Furthermore, 8f and 8k could inhibit FGFR1 phosphorylation and downstream signaling pathways as well as induce cell apoptosis. In vivo, 8f and 8k suppress tumor growth in the SNU-16 xenograft model without inducing obvious toxicity. These findings raise the possibility that compounds 8f and 8k might serve as potential agents for the treatment of gastric cancer.

Detection of a novel panel of 24 genes with high frequencies of mutation in gastric cancer based on next-generation sequencing

BACKGROUND

Gastric cancer is a leading cause of cancer-related mortality worldwide. Many somatic mutations have been identified based on next-generation sequencing; they likely play a vital role in cancer treatment selection. However, next-generation sequencing has not been widely used to diagnose and treat gastric cancer in the clinic.

AIM

To test the mutant gene frequency as a guide for molecular diagnosis and personalized therapy in gastric cancer by use of next-generation sequencing.

METHODS

We constructed a panel of 24 mutant genes to detect somatic nucleotide variations and copy number variations based on a next-generation sequencing technique. Our custom panel included high-mutation frequency cancer driver and tumour suppressor genes. Mutated genes were also analyzed using the cBioPortal database. The clinical annotation of important variant mutation sites was evaluated in the ClinVar database. We searched for candidate drugs for targeted therapy and immunotherapy from the OncoKB database.

RESULTS

In our study, the top 16 frequently mutated genes were TP53(58%), ERBB2(28%), BRCA2 (23%), NF1 (19%), PIK3CA (14%), ATR (14%), MSH2 (12%), FBXW7 (12%), BMPR1A (12%), ERBB3 (11%), ATM (9%), FGFR2 (8%), MET (8%), PTEN (6%), CHD4 (6%), and KRAS (5%). TP53 is a commonly mutated gene in gastric cancer and has a similar frequency to that in the cBioPortal database. 33 gastric cancer patients (51.6%) with microsatellite stability and eight patients (12.5%) with microsatellite instability-high were investigated. Enrichment analyses demonstrated that high-frequency mutated genes had transmembrane receptor protein kinase activity. We discovered that BRCA2, PIK3CA, and FGFR2 gene mutations represent promising biomarkers in gastric cancer.

CONCLUSION

We developed a powerful panel of 24 genes with high frequencies of mutation that could detect common somatic mutations. The observed mutations provide potential targets for the clinical treatment of gastric cancer.

FGFR2 overexpression and compromised survival in diffuse-type gastric cancer in a large central European cohort

The significance of fibroblast growth factor receptor 2 (FGFR2) in gastric cancer (GC) has been studied predominantly in Asian patient cohorts. Data on White patients are scarce. Here, we aimed to independently validate the expression and putative tumor biological significance of FGFR2 in a large non-Asian GC cohort. Immunohistochemistry (IHC) was performed on large-area tissue sections from 493 patients with GC and evaluated using the HScore. GCs with moderate and strong FGFR2 expression were studied for Fgfr2 amplification using chromogenic in situ hybridization (CISH). Median overall survival was determined using the Kaplan–Meier method. The majority [240 (99.1%)] of FGFR2-positive GCs showed a variable combination of staining intensities with marked intratumoral heterogeneity, including weak [198 (40.2%) cases], moderate [145 (29.4%)], and strong [108 (21.9%)] staining in diverse combinations. 250 (50.9%) GCs expressed no FGFR2. Fgfr2 gene amplification was found in 40% of selected cases with high protein expression and was also heterogeneous at the cell level. FGFR2 protein expression did not correlate with patient survival in the entire cohort However, using different cutoff values, a negative correlation between FGFR2-expression and patient outcome was found for diffuse-type GC. FGFR2 expression was associated with a lower tumor grade and intestinal phenotype (p≤0.0001). FGFR2–positive diffuse-type GCs classify a small subset of patients with a poor tumor specific survival (5.29±1.3 vs. 14.67±1.9 months; p = 0.004).

Gastric Cancer: Mechanisms, Biomarkers, and Therapeutic Approaches

Gastric cancer (GC) remains one of the most common deadly malignancies worldwide. Recently, several targeted therapeutics for treating unresectable or metastatic GC have been developed. Comprehensive characterization of the molecular profile and of the tumor immune microenvironment of GC has allowed researchers to explore promising biomarkers for GC treatment and has enabled a new paradigm in precision-targeted immunotherapy. In this article, we review established and promising new biomarkers relevant in GC, with a focus on their clinical implications, diagnostic methods, and the efficacy of targeted agents.

Prospective analysis of the expression status of FGFR2 and HER2 in colorectal and gastric cancer populations: DS-Screen Study

PURPOSE

Fibroblast growth factor receptor 2 (FGFR2) and human epidermal growth factor receptor 2 (HER2) proteins are both molecular targets for cancer therapy. The objective of this study was to evaluate the expression status of FGFR2 and HER2 in patients with gastric cancer (GC) or colorectal cancer (CRC).

METHODS

Archived tumor tissue samples from patients with histologically-confirmed GC or CRC suitable for chemotherapy were analyzed for FGFR2 and HER2 expression using immunohistochemistry and fluorescence in situ hybridization (HER2 in CRC only).

RESULTS

A total of 176 GC patients and 389 CRC patients were enrolled. Among patients with GC, 25.6% were FGFR2-positive and 26.1% were HER2-positive. Among patients with CRC, 2.9% were FGFR2-positive and 16.2% were HER2-positive. No clear relationship was found between FGFR2 and HER2 status in either GC or CRC. In GC, FGFR2 and HER2 statuses did not differ between different primary cancer locations, whereas there were some differences between histological types. Based on FGFR2- and/or HER2-positive status, 117 patients were identified as potentially suitable for inclusion in clinical trials of therapeutic agents targeting the relevant protein (GC = 45, CRC = 72; FGFR = 56, HER2 = 62), of whom 7 were eventually enrolled into such clinical trials.

CONCLUSIONS

This study indicated the prevalence of FGFR2 and HER2 in GC and CRC in the Japanese population. The screening performed in this study could be useful for identifying eligible patients for future clinical trials of agents targeting these proteins.

TRIAL REGISTRATION

Clinical trial registration Japic CTI No.: JapicCTI-163380.  https://www.

CLINICALTRIALS

jp/cti-user/trial/ShowDirect.jsp?directLink=RNlzx1PPCuT.PrVNPxPRwA .

Receptor Tyrosine Kinases and Their Signaling Pathways as Therapeutic Targets of Curcumin in Cancer

Receptor tyrosine kinases (RTKs) are transmembrane cell-surface proteins that act as signal transducers. They regulate essential cellular processes like proliferation, apoptosis, differentiation and metabolism. RTK alteration occurs in a broad spectrum of cancers, emphasising its crucial role in cancer progression and as a suitable therapeutic target. The use of small molecule RTK inhibitors however, has been crippled by the emergence of resistance, highlighting the need for a pleiotropic anti-cancer agent that can replace or be used in combination with existing pharmacological agents to enhance treatment efficacy. Curcumin is an attractive therapeutic agent mainly due to its potent anti-cancer effects, extensive range of targets and minimal toxicity. Out of the numerous documented targets of curcumin, RTKs appear to be one of the main nodes of curcumin-mediated inhibition. Many studies have found that curcumin influences RTK activation and their downstream signaling pathways resulting in increased apoptosis, decreased proliferation and decreased migration in cancer both in vitro and in vivo. This review focused on how curcumin exhibits anti-cancer effects through inhibition of RTKs and downstream signaling pathways like the MAPK, PI3K/Akt, JAK/STAT, and NF-κB pathways. Combination studies of curcumin and RTK inhibitors were also analysed with emphasis on their common molecular targets.

Preclinical characterization of bemarituzumab, an anti-FGFR2b antibody for the treatment of cancer

Bemarituzumab (FPA144) is a first-in-class, humanized, afucosylated immunoglobulin G1 monoclonal antibody (mAb) directed against fibroblast growth factor receptor 2b (FGFR2b) with two mechanisms of action against FGFR2b-overexpressing tumors: inhibition of FGFR2b signaling and enhanced antibody-dependent cell-mediated cytotoxicity (ADCC). Bemarituzumab is being developed as a cancer therapeutic, and we summarize here the key nonclinical data that supported moving it into clinical trials. Bemarituzumab displayed sub-nanomolar cross-species affinity for FGFR2b receptors, with >20-fold enhanced binding affinity to human Fc gamma receptor IIIa compared with the fucosylated version. In vitro, bemarituzumab induced potent ADCC against FGFR2b-expressing tumor cells, and inhibited FGFR2 phosphorylation and proliferation of SNU-16 gastric cancer cells in a concentration-dependent manner. In vivo, bemarituzumab inhibited tumor growth through inhibition of the FGFR2b pathway and/or ADCC in mouse models. Bemarituzumab demonstrated enhanced anti-tumor activity in combination with chemotherapy, and due to bemarituzumab-induced natural killer cell-dependent increase in programmed death-ligand 1, also resulted in enhanced anti-tumor activity when combined with an anti-programmed death-1 antibody. Repeat-dose toxicity studies established the highest non-severely-toxic dose at 1 and 100 mg/kg in rats and cynomolgus monkeys, respectively. In pharmacokinetic (PK) studies, bemarituzumab exposure increase was greater than dose-proportional, with the linear clearance in the expected dose range for a mAb. The PK data in cynomolgus monkeys were used to project bemarituzumab linear PK in humans, which were consistent with the observed human Phase 1 data. These key nonclinical studies facilitated the successful advancement of bemarituzumab into the clinic.

The beginning of the era of precision medicine for gastric cancer with fibroblast growth factor receptor 2 aberration

Despite recent advances in the systemic treatment of metastatic gastric cancer (GC), prognostic outcomes remain poor. Considerable research effort has been invested in characterizing the genomic landscape of GC and identifying potential therapeutic targets. FGFR2 is one of the most attractive targets because aberrations in this gene are frequently associated with GC, particularly the diffuse type in Lauren's classification, which confers an unfavorable prognosis. Based on the preclinical data, the FGFR2 signaling pathway plays a key role in the development and progression of GC, and several FGFR inhibitors have been clinically assessed. However, the lack of robust treatment efficacy has hampered precision medicine for patients with FGFR2-aberrant GC. Recently, the clinical benefits of the FGFR2-IIIb-selective monoclonal antibody bemarituzumab for FGFR2b-positive GC patients were shown in a randomized phase II FIGHT trial of bemarituzumab combined with the first-line chemotherapy. This trial demonstrates proof of concept, suggesting that FGFR2 is a relevant therapeutic target for patients with FGFR2b-positive GC and that bemarituzumab brings new hope for diffuse-type GC patients. In this review, we summarize the oncogenic roles of FGFR2 signaling and highlight the most recent advances in FGFR inhibitors based on the findings of pivotal clinical trials for patients with FGFR2-aberrant GC. Thus, the era of precision medicine for patients with FGFR2-aberrant GC will be opened.

Circulating Tumor DNA Analysis Detects FGFR2 Amplification and Concurrent Genomic Alterations Associated with FGFR Inhibitor Efficacy in Advanced Gastric Cancer

PURPOSE

FGFR2 amplification is associated with poor prognosis in advanced gastric cancer and its subclonal heterogeneity has been revealed. Here, we examined whether circulating tumor DNA (ctDNA) was useful for detecting FGFR2 amplification and co-occurring resistance mechanisms in advanced gastric cancer.

EXPERIMENTAL DESIGN

We assessed genomic characteristics of FGFR2-amplified advanced gastric cancer in a nationwide ctDNA screening study. We also analyzed FGFR2 amplification status in paired tissue and plasma samples with advanced gastric cancer. In addition, we examined patients with FGFR2-amplified advanced gastric cancer identified by ctDNA sequencing who received FGFR inhibitors.

RESULTS

FGFR2 amplification was more frequently detected by ctDNA sequencing in 28 (7.7%) of 365 patients with advanced gastric cancer than by tissue analysis alone (2.6%-4.4%). FGFR2 amplification profiling of paired tissue and plasma revealed that FGFR2 amplification was detectable only by ctDNA sequencing in 6 of 44 patients, which was associated with a worse prognosis. Two patients in whom FGFR2 amplification was detected by ctDNA sequencing after tumor progression following previous standard chemotherapies but not by pretreatment tissue analysis had tumor responses to FGFR inhibitors. A third patient with FGFR2 and MET co-amplification in ctDNA showed a limitation of benefit from FGFR inhibition, accompanied by a marked increase in the MET copy number.

CONCLUSIONS

ctDNA sequencing identifies FGFR2 amplification missed by tissue testing in patients with advanced gastric cancer, and these patients may respond to FGFR inhibition. The utility of ctDNA sequencing warrants further evaluation to develop effective therapeutic strategies for patients with FGFR2-amplified advanced gastric cancer.

Spatial profiling of gastric cancer patient-matched primary and locoregional metastases reveals principles of tumour dissemination

OBJECTIVE

Endoscopic mucosal biopsies of primary gastric cancers (GCs) are used to guide diagnosis, biomarker testing and treatment. Spatial intratumoural heterogeneity (ITH) may influence biopsy-derived information. We aimed to study ITH of primary GCs and matched lymph node metastasis (LN_met).

DESIGN

GC resection samples were annotated to identify primary tumour superficial (PT_sup), primary tumour deep (PT_deep) and LN_met subregions. For each subregion, we determined (1) transcriptomic profiles (NanoString 'PanCancer Progression Panel', 770 genes); (2) next-generation sequencing (NGS, 225 gastrointestinal cancer-related genes); (3) DNA copy number profiles by multiplex ligation-dependent probe amplification (MLPA, 16 genes); and (4) histomorphological phenotypes.

RESULTS

NanoString profiling of 64 GCs revealed no differences between PT_sup1 and PT_sup2, while 43% of genes were differentially expressed between PT_sup versus PT_deep and 38% in PT_sup versus LN_met. Only 16% of genes were differently expressed between PT_deep and LN_met. Several genes with therapeutic potential (eg IGF1, PIK3CD and TGFB1) were overexpressed in LN_met and PT_deep compared with PT_sup. NGS data revealed orthogonal support of NanoString results with 40% mutations present in PT_deep and/or LN_met, but not in PT_sup. Conversely, only 6% of mutations were present in PT_sup and were absent in PT_deep and LN_met. MLPA demonstrated significant ITH between subregions and progressive genomic changes from PT_sup to PT_deep/LN_met.

CONCLUSION

In GC, regional lymph node metastases are likely to originate from deeper subregions of the primary tumour. Future clinical trials of novel targeted therapies must consider assessment of deeper subregions of the primary tumour and/or metastases as several therapeutically relevant genes are only mutated, overexpressed or amplified in these regions.

SHP2 as a Potential Therapeutic Target in Diffuse-Type Gastric Carcinoma Addicted to Receptor Tyrosine Kinase Signaling

Simple Summary

Diffuse-type gastric carcinoma (DGC) is characterized by rapid infiltrative growth associated with massive stroma and frequent peritoneal dissemination, which leads to poor patient outcomes. In this study, we found that the oncogenic tyrosine phosphatase SHP2 is tyrosine-phosphorylated downstream of the amplified receptor tyrosine kinases (RTKs) Met and fibroblast growth factor receptor 2 (FGFR2) in DGC cell lines. SHP2 knockdown or pharmacological inhibition selectively suppressed the growth of DGC addicted to amplified Met and FGFR2. Moreover, targeting SHP2 abrogated malignant phenotypes, including peritoneal dissemination, of Met-addicted DGC and could overcome acquired resistance to Met inhibitors. Our findings suggest that SHP2 is a potential target for the treatment of DGC addicted to amplified RTK signaling.

Abstract

Diffuse-type gastric carcinoma (DGC) exhibits aggressive progression associated with rapid infiltrative growth, massive fibrosis, and peritoneal dissemination. Gene amplification of Met and fibroblast growth factor receptor 2 (FGFR2) receptor tyrosine kinases (RTKs) has been observed in DGC. However, the signaling pathways that promote DGC progression downstream of these RTKs remain to be fully elucidated. We previously identified an oncogenic tyrosine phosphatase, SHP2, using phospho-proteomic analysis of DGC cells with Met gene amplification. In this study, we characterized SHP2 in the progression of DGC and assessed the therapeutic potential of targeting SHP2. Although SHP2 was expressed in all gastric carcinoma cell lines examined, its tyrosine phosphorylation preferentially occurred in several DGC cell lines with Met or FGFR2 gene amplification. Met or FGFR inhibitor treatment or knockdown markedly reduced SHP2 tyrosine phosphorylation. Knockdown or pharmacological inhibition of SHP2 selectively suppressed the growth of DGC cells addicted to Met or FGFR2, even when they acquired resistance to Met inhibitors. Moreover, SHP2 knockdown or pharmacological inhibition blocked the migration and invasion of Met-addicted DGC cells in vitro and their peritoneal dissemination in a mouse xenograft model. These results indicate that SHP2 is a critical regulator of the malignant progression of RTK-addicted DGC and may be a therapeutic target.

Current and potential biomarkers in gastric cancer: a critical review of the literature

Gastric cancer is the fourth most common type of cancer worldwide and the second most lethal. Gastric cancer biomarkers can be used for diagnosis, prediction of sensitivity to treatment, and prognosis. The following search terms were applied to PubMed as of December 2020: 'gastric cancer classification', 'gastric cancer epidemiology', 'cancer metastasis' and 'gastric cancer biomarker'. Only experimental studies were reported in the 'biomarkers' section. Some biomarkers can serve as therapeutic targets for antitumoral drugs. The genes analyzed include E-cadherin, RPRM, XAF1, MINT25, TFF1, p16 and p53. The miRNAs analyzed include miR-18a, miR185-5p, miR-125b and miR-21. Some molecules were associated with metastasis of gastric cancer, specifically those involved with EMT process and tissue degradation.

Cancer-related FGFR2 overexpression and gene amplification in Japanese patients with gastric cancer

OBJECTIVE

Fibroblast growth factor receptor 2 (FGFR2) has been proposed as a novel druggable target in unresectable gastric cancer. FGFR2 alteration has been reported as associated with poor prognosis even in patients with gastric cancer who received systemic chemotherapy. This study aimed to evaluate the frequency of FGFR2 overexpression and gene amplification in clinical specimens from Japanese patients with recurrent or unresectable gastric cancer.

METHODS

This observational study enrolled patients who were histologically or cytologically confirmed with unresectable HER2-negative or unknown gastric or gastroesophageal junctional adenocarcinoma treated with at least one previous chemotherapy. FGFR2 overexpression and gene amplification in the specimens were evaluated by immunohistochemical staining and fluorescence in situ hybridization methods, respectively.

RESULTS

In a total of 173 eligible cases, FGFR2 immunohistochemistry score was evaluated as 0, 1, 2, 3 and 4 for 20, 80, 35, 28 and 10 cases, respectively. In 151 evaluable cases with FGFR2 immunohistochemistry scores of 1-4, FGFR2 copy number expressed as fluorescence in situ hybridization signals were detected as <4, ≥4 < 10 and ≥10 copies for 123, 16 and 12 cases, respectively. FGFR2 copy number showed an increasing tendency along with higher FGFR2 immunohistochemistry scores in the corresponding specimen. The response rate and time to treatment failure for first line chemotherapy did not have any obvious relationship to FGFR2 immunohistochemistry score and FGFR2 copy number.

CONCLUSIONS

Although FGFR2 overexpression and gene amplification were shown in Japanese patients with unresectable gastric cancer, these alterations did not impact the effects of cytotoxic agents as first line chemotherapy.

Fibroblast Growth Factor Receptors (FGFRs) and Noncanonical Partners in Cancer Signaling

Increasing evidence indicates that success of targeted therapies in the treatment of cancer is context-dependent and is influenced by a complex crosstalk between signaling pathways and between cell types in the tumor. The Fibroblast Growth Factor (FGF)/FGF receptor (FGFR) signaling axis highlights the importance of such context-dependent signaling in cancer. Aberrant FGFR signaling has been characterized in almost all cancer types, most commonly non-small cell lung cancer (NSCLC), breast cancer, glioblastoma, prostate cancer and gastrointestinal cancer. This occurs primarily through amplification and over-expression of FGFR1 and FGFR2 resulting in ligand-independent activation. Mutations and translocations of FGFR1-4 are also identified in cancer. Canonical FGF-FGFR signaling is tightly regulated by ligand-receptor combinations as well as direct interactions with the FGFR coreceptors heparan sulfate proteoglycans (HSPGs) and Klotho. Noncanonical FGFR signaling partners have been implicated in differential regulation of FGFR signaling. FGFR directly interacts with cell adhesion molecules (CAMs) and extracellular matrix (ECM) proteins, contributing to invasive and migratory properties of cancer cells, whereas interactions with other receptor tyrosine kinases (RTKs) regulate angiogenic, resistance to therapy, and metastatic potential of cancer cells. The diversity in FGFR signaling partners supports a role for FGFR signaling in cancer, independent of genetic aberration.

Novel targetable FGFR2 and FGFR3 alterations in glioblastoma associate with aggressive phenotype and distinct gene expression programs

Prognostic molecular subgrouping of glioblastoma is an ongoing effort and the current classification includes IDH-wild-type and IDH-mutant entities, the latter showing significantly better prognosis. We performed a comparative integrated analysis of the FGFR glioblastoma subgroup consisting of 5 cases from a prospective 101-patient-cohort. FGFR alterations included FGFR2-TACC2 and FGFR2 amplifications arising in a multifocal IDH-mutant glioblastoma with unexpected 2.5-month patient survival, novel FGFR3 carboxy-terminal duplication and FGFR3-TLN1 fusion, and two previously described FGFR3-TACC3 fusions. The FGFR2 tumors showed additional mutations in SERPINE1/PAI-1 and MMP16, as part of extensive extracellular matrix remodeling programs. Whole transcriptomic analysis revealed common proliferation but distinct morphogenetic gene expression programs that correlated with tumor histology. The kinase program revealed EPHA3, LTK and ALK receptor tyrosine kinase overexpression in individual FGFR tumors. Paradoxically, all FGFR-fused glioblastomas shared strong PI3K and MAPK pathway suppression effected by SPRY, DUSP and AKAP12 inhibitors, whereas the FGFR2-TACC2 tumor elicited also EGFR suppression by ERRFI1 upregulation. This integrated analysis outlined the proliferation and morphogenetic expression programs in FGFR glioblastoma, and identified four novel, clinically targetable FGFR2 and FGFR3 alterations that confer aggressive phenotype and trigger canonical pathway feedback inhibition, with important therapeutic implications.

MET-Pyk2 Axis Mediates Acquired Resistance to FGFR Inhibition in Cancer Cells

Deregulation of fibroblast growth factor receptors (FGFRs) signaling, as a result of FGFR amplification, chromosomal translocation, or mutations, is involved in both initiation and progression of a wide range of human cancers. Clinical data demonstrating the dependence of cancer cells on FGFRs signaling clearly indicate these receptors as the molecular targets of anti-cancer therapies. Despite the increasing number of tyrosine kinase inhibitors (TKIs) being investigated in clinical trials, acquired resistance to these drugs poses a serious therapeutic problem. In this study, we focused on a novel pan-FGFR inhibitor-CPL304110, currently being investigated in phase I clinical trials in adults with advanced solid malignancies. We analyzed the sensitivity of 17 cell lines derived from cancers with aberrant FGFR signaling, i.e. non-small cell lung cancer, gastric and bladder cancer to CPL304110. In order to explore the mechanism of acquired resistance to this FGFR inhibitor, we developed from sensitive cell lines their variants resistant to CPL304110. Herein, for the first time we revealed that the process of acquired resistance to the novel FGFR inhibitor was associated with increased expression of MET in lung, gastric, and bladder cancer cells. Overexpression of MET in NCI-H1703, SNU-16, RT-112 cells as well as treatment with HGF resulted in the impaired response to inhibition of FGFR activity. Moreover, we demonstrated that cells with acquired resistance to FGFR inhibitor as well as cells overexpressing MET displayed enhanced migratory abilities what was accompanied with increased levels of Pyk2 expression. Importantly, inhibition of both MET and Pyk2 activity restored sensitivity to FGFR inhibition in these cells. Our results demonstrate that the HGF/MET-Pyk2 signaling axis confers resistance to the novel FGFR inhibitor, and this mechanism is common for lung, gastric, and bladder cancer cells. Our study suggests that targeting of MET/Pyk2 could be an approach to overcome resistance to FGFR inhibition.

Clinical difference between fibroblast growth factor receptor 2 subclass, type IIIb and type IIIc, in gastric cancer

Fibroblast growth factor receptor 2 (FGFR2) has two isoforms: IIIb type and IIIc type. Clinicopathologic significance of these two FGFR2 subtypes in gastric cancer remains to be known. This study aimed to clarify the clinicopathologic difference of FGFR2IIIb and/or FGFR2IIIc overexpression. A total of 562 patients who underwent gastrectomy was enrolled. The expressions of FGFR2IIIb and FGFR2IIIc were retrospectively examined by immunohistochemistry or fluorescence in situ hybridization (FISH) using the 562 gastric tumors. We evaluated the correlation between clinicopathologic features and FGFR2IIIb overexpression and/or FGFR2IIIc overexpression in gastric cancer. FGFR2IIIb overexpression was observed in 28 cases (4.9%), and FGFR2IIIc overexpression was observed in four cases (0.7%). All four FGFR2IIIc cases were also positive for FGFR2IIIb, but not in the same cancer cells. FGFR2IIIb and/or FGFR2IIIc overexpression was significantly correlated with lymph node metastasis and clinical stage. Both FGFR2IIIb and FGFR2IIIc were significantly associated with poor overall survival. A multivariate analysis showed that FGFR2IIIc expression was significantly correlated with overall survival. FISH analysis indicated that FGFR2 amplification was correlated with FGFR2IIIb and/or FGFR2IIIc overexpression. These findings suggested that gastric tumor overexpressed FGFR2IIIc and/or FGFR2IIIb at the frequency of 4.9%. FGFR2IIIc overexpression might be independent prognostic factor for patients with gastric cancer.

SPA: A Quantitation Strategy for MS Data in Patient-derived Xenograft Models

With the development of mass spectrometry (MS)-based proteomics technologies, patient-derived xenograft (PDX), which is generated from the primary tumor of a patient, is widely used for the proteome-wide analysis of cancer mechanism and biomarker identification of a drug. However, the proteomics data interpretation is still challenging due to complex data deconvolution from the PDX sample that is a cross-species mixture of human cancerous tissues and immunodeficient mouse tissues. In this study, by using the lab-assembled mixture of human and mouse cells with different mixing ratios as a benchmark, we developed and evaluated a new method, SPA (shared peptide allocation), for protein quantitation by considering the unique and shared peptides of both species. The results showed that SPA could provide more convenient and accurate protein quantitation in human–mouse mixed samples. Further validation on a pair of gastric PDX samples (one bearing FGFR2 amplification while the other one not) showed that our new method not only significantly improved the overall protein identification, but also detected the differential phosphorylation of FGFR2 and its downstream mediators (such as RAS and ERK) exclusively. The tool pdxSPA is freely available at https://github.com/Li-Lab-Proteomics/pdxSPA.

Checkpoint inhibitors for gastroesophageal cancers: dissecting heterogeneity to better understand their role in first-line and adjuvant therapy

Gastroesophageal adenocarcinoma (GEA) and squamous esophageal cancer (ESCC) are responsible for >1 million deaths annually globally. Until now, patients with metastatic GEA and ESCC could anticipate survival of <1 year. Anti- programmed cell death protein 1 (anti-PD-1) monotherapy has demonstrated modest efficacy in previously treated GEA and ESCC. In 2020, four pivotal trials have established anti-PD-1 therapy as a new standard of care for selected GEA and ESCC patients as first-line advanced and adjuvant therapy. In this review, we discuss the recent results of the CheckMate 649, ATTRACTION-4, KEYNOTE-590 and CheckMate 577 trials. We consider these results in the context of current standards of care and historical trials of immune checkpoint blockade in GEA and ESCC. We explore biomarker selection for anti-PD-1 therapy and appraise the future of combination therapies. In CheckMate 649, treatment with oxaliplatin-fluoropyrimidine chemotherapy plus nivolumab in patients with combined positive score ≥5 GEA tumors provided a clinically meaningful and statistically significant improvement in overall survival. The ATTRACTION-4 trial did not see a similar overall survival benefit, despite a clear improvement in progression-free survival. We review potential explanations for this result. KEYNOTE-590 showed profoundly improved survival when pembrolizumab was added to cisplatin-fluoropyrimidine chemotherapy in ESCC patients with combined positive score ≥10 tumors; this benefit was less convincing in unselected ESCC. Finally, CheckMate 577 provides proof-of-concept for the improvement in disease-free survival with adjuvant nivolumab in high-risk resected GEA and ESCC following trimodality therapy. Immune checkpoint blockade has come of age in GEA and ESCC, and will now be integrated into first-line and earlier lines of therapy, providing benefit for a larger proportion of patients. Biomarker standardization will be critical to select the patients most likely to benefit from treatment. For patients with immune evasive tumors, novel combinations under development show promise; however, global trials are needed.

The impact of recent next generation sequencing and the need for a new classification in gastric cancer

The phenotypical and molecular heterogeneity of gastric cancer has hampered the introduction in clinical practice of a unifying classification of the disease. However, as next generation sequencing (NGS) technologies enhanced the comprehension of the molecular landscape of gastric cancer, novel molecular classification systems have been proposed, allowing the dissection of molecular tumor heterogeneity and paving the way for the development of new targeted therapies. Moreover, the use of NGS analyses in the molecular profiling of formalin-fixed paraffin-embedded (FFPE) specimens will improve patient selection for the enrolment in novel clinical trials. In conclusion, the application of NGS in precision oncology will revolutionize the diagnosis and clinical management in gastric cancer patients.

Rapid Resistance of FGFR-driven Gastric Cancers to Regorafenib and Targeted FGFR Inhibitors can be Overcome by Parallel Inhibition of MEK

Amplification or overexpression of the FGFR family of receptor tyrosine kinases occurs in a significant proportion of gastric cancers. Regorafenib is a multikinase inhibitor of angiogenic and oncogenic kinases, including FGFR, which showed activity in the randomized phase II INTEGRATE clinical trial in advanced gastric cancer. There are currently no biomarkers that predict response to this agent, and whether regorafenib is preferentially active in FGFR-driven cancers is unknown. Through screening 25 gastric cancer cell lines, we identified five cell lines that were exquisitely sensitive to regorafenib, four of which harbored amplification or overexpression of FGFR family members. These four cell lines were also sensitive to the FGFR-specific inhibitors, BGJ398, erdafitinib, and TAS-120. Regorafenib inhibited FGFR-driven MAPK signaling in these cell lines, and knockdown studies confirmed their dependence on specific FGFRs for proliferation. In the INTEGRATE trial cohort, amplification or overexpression of FGFRs 1-4 was detected in 8%-19% of cases, however, this was not associated with improved progression-free survival and no objective responses were observed in these cases. Further preclinical analyses revealed FGFR-driven gastric cancer cell lines rapidly reactivate MAPK/ERK signaling in response to FGFR inhibition, which may underlie the limited clinical response to regorafenib. Importantly, combination treatment with an FGFR and MEK inhibitor delayed MAPK/ERK reactivation and synergistically inhibited proliferation of FGFR-driven gastric cancer cell lines. These findings suggest that upfront combinatorial inhibition of FGFR and MEK may represent a more effective treatment strategy for FGFR-driven gastric cancers.

A comparative study of RTK gene status between primary tumors, lymph-node metastases, and Krukenberg tumors

Krukenberg tumor (KT) refers to a rare ovarian tumor that has metastasized from a primary site. Patients with KTs have a poorer prognosis and worse survival. Thus far, little is known about the frequency of receptor tyrosine kinase (RTK) gene amplification and the concordance of gene amplification between primary tumors, lymph-node metastases, and KTs. Herein, 50 paired samples, including primary cancers, metastatic lymph nodes, and KTs were collected, and RTK gene amplification was tested by fluorescence in situ hybridization (FISH). There were four cases positive for human epidermal growth factor receptor type 2 (HER2) amplification, all of which showed conversion of HER2 status between different lesions. Of the two cases with c-mesenchymal-epithelial transition (c-MET) amplification, the primary tumors and lymph nodes were negative while the right involved ovaries were positive. Inconsistent fibroblast growth factor receptor 2 (FGFR2) status in different lesions was observed in three of the six FGFR2-amplified cases. Co-amplification of RTK genes was identified in only one patient for primary cancer and two for KTs. Collectively, there were 46, 48, 50, and 44 cases negative for HER2, c-MET, EGFR, and FGFR2 amplification in all lesions, respectively. There was no significant difference in overall survival between KTs of gastric origin and colorectal origin. However, of all synchronous cancers, KTs of colorectal origin had a better prognosis than those of gastric origin. In conclusion, the positive rate of RTK gene amplification in KTs was low. Intratumoral heterogeneity was frequent in KTs with RTK gene amplification. A mutually exclusive pattern of RTK gene amplification was dominant in primary cancers, lymph-node metastases, and KTs. There was no survival difference between KTs of gastric origin and colorectal origin. However, of all synchronous cancers, KTs of colorectal origin had a better prognosis than those of gastric origin.

Clinical complexity of utilizing FGFR inhibitors in cancer therapeutics

INTRODUCTION

Fibroblast growth factor receptors (FGFR 1-4) are a highly conserved family of receptor tyrosine kinases, involved in several physiological processes. Genetic aberrations of FGFRs and their ligands, fibroblast growth factors (FGFs) are involved in several pathological processes including cancer. The FGF-FGFR axis has emerged as a treatment target in oncology. Because these aberrations drive cancer progression, the development of FGFR targeted therapies have been accelerated.

AREAS COVERED

In this comprehensive review, we evaluate molecular pathology and targeted therapies to FGFRs. We reviewed the evidence for safety and efficacy from preclinical and clinical studies (phase I-III) of FGFR targeted therapies. We also discuss potential challenges in bringing these targeted therapies from bench to bedside and the potential opportunities.

EXPERT OPINION

Despite the challenges of the clinical development of FGFR targeted therapies, two FGFR small-molecule inhibitors, namely Erdafitinib and Pemigatinib, are FDA approved for urothelial cancer and cholangiocarcinoma, respectively. Understanding and detection of FGFR genomic aberrations, protein overexpression and the development of isoform-specific inhibitors are factors in the clinical success of these therapies. An enhanced understanding of patient selection based on a gene signatures or biomarkers is key to success of FGFR targeted therapies.