Fibroblast growth factor receptor 2 gene amplification status and its clinicopathologic significance in gastric carcinoma

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.

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.

Cancer-associated fibroblasts secrete FGF5 to inhibit ferroptosis to decrease cisplatin sensitivity in nasopharyngeal carcinoma through binding to FGFR2

Cisplatin (DDP)-based chemoradiotherapy is one of the standard treatments for nasopharyngeal carcinoma (NPC). However, the sensitivity and side effects of DDP to patients remain major obstacles for NPC treatment. This research aimed to study DDP sensitivity regulated by cancer-associated fibroblasts (CAFs) through modulating ferroptosis. We demonstrated that DDP triggered ferroptosis in NPC cells, and it inhibited tumor growth via inducing ferroptosis in xenograft model. CAFs secreted high level of FGF5, thus inhibiting DDP-induced ferroptosis in NPC cells. Mechanistically, FGF5 secreted by CAFs directly bound to FGFR2 in NPC cells, leading to the activation of Keap1/Nrf2/HO-1 signaling. Rescued experiments indicated that FGFR2 overexpression inhibited DDP-induced ferroptosis, and CAFs protected against DDP-induced ferroptosis via FGF5/FGFR2 axis in NPC cells. In vivo data further showed the protective effects of FGF5 on DDP-triggered ferroptosis in NPC xenograft model. In conclusion, CAFs inhibited ferroptosis to decrease DDP sensitivity in NPC through secreting FGF5 and activating downstream FGFR2/Nrf2 signaling. The therapeutic strategy targeting FGF5/FGFR2 axis from CAFs might augment DDP sensitivity, thus decreasing the side effects of DDP in NPC treatment.

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.

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.

Adénocarcinome œsogastrique – nouvelles cibles thérapeutiques

The median overall survival of metastatic esophagogastric adenocarcinoma is approximately twelve months. In fifteen years, major breakthrough have been the targeting of HER2 overexpression and more recently immunotherapy in patients with CPS≥5. Recent advances in molecular biology have identified some molecular alterations in esophageal adenocarcinoma, interesting to target. FGFR2 is overexpressed in one third of patients, and its targeting with a specific monoclonal antibody bemarituzumab showed a significant improvement in survival. Claudin 18.2 (CLDN 18.2) is overexpressed in at least a third of esophagogastric adenocarcinomas. The combination of zolbetuximab and chemotherapy provides a survival benefit, correlated with the intensity of CLDN 18.2 expression. The potential interest of targeting other pathways is under investigation in several trials with some encouraging preliminary data, and early trials in these indications, justifying considering large molecular screening in patients who might be candidate for early phase trial. Finally, with the recent advent of immunotherapy, one of the future challenges will be to optimize it through combination strategies with targeted therapies. The combination of anti-angiogenic and immunotherapy seems promising in gastric cancer.

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.

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.

Signaling Pathway and Small-Molecule Drug Discovery of FGFR: A Comprehensive Review

Targeted therapy is a groundbreaking innovation for cancer treatment. Among the receptor tyrosine kinases, the fibroblast growth factor receptors (FGFRs) garnered substantial attention as promising therapeutic targets due to their fundamental biological functions and frequently observed abnormality in tumors. In the past 2 decades, several generations of FGFR kinase inhibitors have been developed. This review starts by introducing the biological basis of FGF/FGFR signaling. It then gives a detailed description of different types of small-molecule FGFR inhibitors according to modes of action, followed by a systematic overview of small-molecule-based therapies of different modalities. It ends with our perspectives for the development of novel FGFR inhibitors.

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).

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.

Biomarker-targeted therapies for advanced-stage gastric and gastro-oesophageal junction cancers: an emerging paradigm

Advances in cancer biology and sequencing technology have enabled the selection of targeted and more effective treatments for individual patients with various types of solid tumour. However, only three molecular biomarkers have thus far been demonstrated to predict a response to targeted therapies in patients with gastric and/or gastro-oesophageal junction (G/GEJ) cancers: HER2 positivity for trastuzumab and trastuzumab deruxtecan, and microsatellite instability (MSI) status and PD-L1 expression for pembrolizumab. Despite this lack of clinically relevant biomarkers, distinct molecular subtypes of G/GEJ cancers have been identified and have informed the development of novel agents, including receptor tyrosine kinase inhibitors and monoclonal antibodies, several of which are currently being tested in ongoing trials. Many of these trials include biomarker stratification, and some include analysis of circulating tumour DNA (ctDNA), which both enables the noninvasive assessment of biomarker expression and provides an indication of the contributions of intratumoural heterogeneity to response and resistance. The results of these studies might help to optimize the selection of patients to receive targeted therapies, thus facilitating precision medicine approaches for patients with G/GEJ cancers. In this Review, we describe the current evidence supporting the use of targeted therapies in patients with G/GEJ cancers and provide guidance on future research directions.

Harnessing biomarkers of response to improve therapy selection in esophago-gastric adenocarcinoma

Advanced esophago-gastric (OG) adenocarcinomas have a high mortality rate and new therapeutic options are urgently required. Despite recent advances in understanding the molecular characteristics of OG cancers, tumor heterogeneity poses a challenge in developing new therapeutics capable of improving patient outcomes. Consequently, chemotherapy remains the mainstay of systemic treatment, with the HER2 being the only predictive biomarker routinely targeted in clinical practice. Recent data indicate that immunotherapy will be incorporated into first-line chemotherapy, but further research is required to refine patient selection. This review will summarize the clinical strategies being evaluated to utilize our knowledge of predictive biomarkers with reference to novel therapeutics, and discuss the barriers to implementing precision oncology in OG adenocarcinoma.

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.

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.

Targeted and immunotherapy in the era of personalised gastric cancer treatment

Gastric cancer is a major cause of cancer-related morbidity and mortality worldwide. Advances in targeted medical treatment were scarce in the past and challenged by the marked spatial and temporal biological heterogeneity of gastric cancer. Recent molecular profiling studies have increased our understanding of genetic and epigenetic drivers, leading to better patient selection for drug development. Beyond that, immune-related biomarkers were identified, paving the way for future effective immunotherapy. We systematically reviewed articles from PubMed of the past 10 years, and abstracts from annual meetings of ESMO, ASCO and AACR to summarise the current knowledge about targeted and immunotherapy and outline pathways to future personalised therapy of gastric cancer.

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.

Role of Fibroblast Growth Factors Receptors (FGFRs) in Brain Tumors, Focus on Astrocytoma and Glioblastoma

Despite pharmacological treatments and surgical practice options, the mortality rate of astrocytomas and glioblastomas remains high, thus representing a medical emergency for which it is necessary to find new therapeutic strategies. Fibroblast growth factors (FGFs) act through their associated receptors (FGFRs), a family of tyrosine kinase receptors consisting of four members (FGFR1-4), regulators of tissue development and repair. In particular, FGFRs play an important role in cell proliferation, survival, and migration, as well as angiogenesis, thus their gene alteration is certainly related to the development of the most common diseases, including cancer. FGFRs are subjected to multiple somatic aberrations such as chromosomal amplification of FGFR1; mutations and multiple dysregulations of FGFR2; and mutations, translocations, and significant amplifications of FGFR3 and FGFR4 that correlate to oncogenesis process. Therefore, the in-depth study of these receptor systems could help to understand the etiology of both astrocytoma and glioblastoma so as to achieve notable advances in more effective target therapies. Furthermore, the discovery of FGFR inhibitors revealed how these biological compounds improve the neoplastic condition by demonstrating efficacy and safety. On this basis, this review focuses on the role and involvement of FGFRs in brain tumors such as astrocytoma and glioblastoma.

Salvage systemic therapy for metastatic urothelial carcinoma: an unmet clinical need

INTRODUCTION

Metastatic urothelial carcinoma (mUC) remains a fatal malignancy, despite the recent addition of immune check point inhibitors (ICIs), an FGFR inhibitor and an antibody-drug conjugate (ADC) to the therapeutic armamentarium. The survival rates are particularly dismal after first-line treatment failure, entailing an urgent need for more effective therapies. Advances in understanding biomarkers and identifying targetable molecules have broadened the pathways under investigation in mUC.

AREAS COVERED

This review summarizes mUC salvage therapy options, including chemotherapy, ICI, and novel promising agents, including targeted therapies, ADCs, cytotoxic agents and vaccines. For the literature review, a PubMed search and relevant data presented at international conferences were used.

EXPERT OPINION

The approval of ICIs, FGFR inhibitor erdafitinib and ADC enfortumab vedotin in the salvage setting has transformed the mUC landscape. Yet there are additional promising agents currently under study. Toxicities are observed with ADCs and FGFR inhibitors, but appear manageable in most patients. The molecular heterogeneity and complex tumor biology are challenging barriers for progress in the therapy of mUC. Advances in molecular profiling, defining validated predictive markers, rational combinations of agents and therapeutically actionable targets will help develop personalized compounds with higher efficacy and less toxicity with hopes to improve outcomes for mUC.

Population pharmacokinetic analysis of phase 1 bemarituzumab data to support phase 2 gastroesophageal adenocarcinoma FIGHT trial

Purpose

To report population pharmacokinetic (PK) analysis of the phase 1 study (FPA144-001, NCT02318329) and to select a clinical dose and schedule that will achieve an empirical target trough concentration (C_trough) for an anti-fibroblast growth factor receptor 2b antibody, bemarituzumab.

Methods

Nonlinear mixed-effect modeling was used to analyse PK data. In vitro binding affinity and receptor occupancy of bemarituzumab were determined. Simulation was conducted to estimate dose and schedule to achieve an empirical target C_trough in a phase 2 trial (FIGHT, NCT03694522) for patients receiving first-line treatment combined with modified 5-fluourouracil, oxaliplatin and leucovorin (mFOLFOX6) for gastric and gastroesophageal junction adenocarcinoma.

Results

Bemarituzumab PK is best described by a two-compartment model with parallel linear and nonlinear (Michaelis–Menten) elimination from the central compartment. Albumin, gender, and body weight were identified as the covariates on the linear clearance and/or volume of distribution in the central compartment, and no dose adjustment was warranted. An empirical target of bemarituzumab C_trough of ≥ 60 µg/mL was projected to achieve > 95% receptor occupancy based on in vitro data. Fifteen mg/kg every 2 weeks, with a single dose of 7.5 mg/kg on Cycle 1 Day 8, was projected to achieve the target C_trough on Day 15 in 98% of patients with 96% maintaining the target at steady state, which was confirmed in the FIGHT trial.

Conclusion

A projected dose and schedule to achieve the target C_trough was validated in phase 1 of the FIGHT trial which supported selection of the phase 2 dose and schedule for bemarituzumab.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04139-4) contains supplementary material, which is available to authorized users.

Targeted therapies in metastatic gastric cancer: Current knowledge and future perspectives

Gastric cancer (GC) represents a leading cause of cancer related morbidity and mortality worldwide accounting for more than 1 million of newly diagnosed cases and thousands of deaths every year. In the last decade, the development of targeted therapies and the optimization of already available chemotherapeutic drugs has expanded the available treatment options for advanced GC and granted better survival expectations to the patients. At the same time, global efforts have been undertaken to investigate in detail the genomic and epigenomic heterogeneity of this disease, resulting in the identification of new specific and sensitive predictive and prognostic biomarkers and in innovative molecular classifications based on gene expression profiling. Nonetheless, several randomized studies aimed at exploring new innovative agents, such as immune checkpoint inhibitors, failed to demonstrate clinically meaningful survival advantages. Therefore, it is essential to further improve the molecular characterization of GC subgroups in order to provide researchers and medical oncologists with new tools for patients’ selection and stratification in future clinical development programs and subsequent trials. The aim of the present manuscript is to provide a global overview of the recent molecular classifications from The Cancer Genome Atlas and the Asian Cancer Research Group and to present key promising developments in the field of immunotherapy and targeted therapies in metastatic GC.

[FGFR3 overexpression is a relevant alteration in colorectal cancer]

BACKGROUND

Fibroblast growth factor receptor (FGFR) signalling plays an important role in embryogenesis as well as in tumorigenesis. In current studies FGFR has proved to be a potential molecular target in a variety of solid tumours. In colorectal cancer (CRC) data on FGFR alterations is very sparse. However, there is a huge need for targeted therapies in this tumour entity with an incidence of 140,000 individuals (USA 2018) and a 5-year relative survival rate of only 14% in metastatic disease.

OBJECTIVES

This article shall provide an overview of the FGFRs and the most frequent FGF ligand alterations in primary and metastatic CRC.

RESULTS

In primary tumours and metastases various FGFR and FGF alterations can be observed. Primary tumours as well as metastases show FGFR alterations at the genomic (by fluorescence in situ hybridization) as well as on the ribonucleic acid (RNA) expression level (by RNA in situ hybridization). In both cohorts FGFR3 overexpression is the most frequent alteration and is associated with an unfavourable prognosis in metastases.

CONCLUSIONS

FGFR3 overexpression defines a subgroup of metastatic colorectal cancers with an unfavourable prognosis. Since FGFR3 alterations can present a potential therapeutic target, patients with FGFR3 overexpression should be included into clinical studies with FGFR inhibitors.

Targeting the Oncogenic FGF-FGFR Axis in Gastric Carcinogenesis

Gastric cancer (GC) is one of the most wide-spread malignancies in the world. The oncogenic role of signaling of fibroblast growing factors (FGFs) and their receptors (FGFRs) in gastric tumorigenesis has been gradually elucidated by recent studies. The expression pattern and clinical correlations of FGF and FGFR family members have been comprehensively delineated. Among them, FGF18 and FGFR2 demonstrate the most prominent driving role in gastric tumorigenesis with gene amplification or somatic mutations and serve as prognostic biomarkers. FGF-FGFR promotes tumor progression by crosstalking with multiple oncogenic pathways and this provides a rational therapeutic strategy by co-targeting the crosstalks to achieve synergistic effects. In this review, we comprehensively summarize the pathogenic mechanisms of FGF-FGFR signaling in gastric adenocarcinoma together with the current targeted strategies in aberrant FGF-FGFR activated GC cases.

Pathologic and prognostic impacts of FGFR2 amplification in gastric cancer: a meta-analysis and systemic review

Fibroblast growth factor receptor-2 (FGFR2) gene is amplified in up to 15% of patients with gastric cancer (GC). However, the prognostic significance of FGFR2 amplification has been controversial. This meta-analysis was conducted to evaluate the clinicopathological impacts of FGFR2 amplification in patients with GC. We performed a systematic computerized search of the electronic databases of PubMed, PMC, EMBASE, Web of Science, and Google Scholar and selected studies assessing the correlation of FGFR2 amplification with pathologic features and/or prognosis in gastric adenocarcinoma. From eight studies, 2,377 patients were included in the pooled analysis of odds ratios (ORs) with 95% confidence intervals (CIs) for pathologic findings and hazard ratios (HRs) with 95% CIs for overall survival. FGFR2 amplification was significantly associated with LN metastasis (OR = 3.93, 95% CI: 2.22-6.96, p < 0.00001) and poorly differentiated adenocarcinoma (OR = 2.36, 95% CI: 1.03-5.39, p = 0.04). In addition, patients with GC harboring FGFR2 amplification showed significantly worse survival (HR = 2.09, 95% CI: 1.68-2.59, p < 0.00001), compared with patients with FGFR2-unamplified GC. In conclusion, this meta-analysis indicates that FGFR2 amplification is an adverse prognostic factor in patients with GC.

The efficacy of cisplatin on nasopharyngeal carcinoma cells may be increased via the downregulation of fibroblast growth factor receptor 2

Cisplatin is one of the primary compounds used in the treatment of nasopharyngeal carcinoma (NPC), and fibroblast growth factor receptor 2 (FGFR2) has emerged to be a promising target for treatment in various tumors. Therefore, the present study aimed to explore whether the expression levels of FGFR2 in NPC tissues and cell lines were altered, and whether the efficiency of cisplatin was increased following the downregulation of FGFR2. The downregulation of FGFR2 was achieved by transfection with a small interfering RNA against FGFR2. Tissues of patients with NPC were analyzed by immunohistochemistry. Cell viability was examined using a Cell Counting Kit‑8 assay. Cell cycle analysis was performed using flow cytometry. mRNA and protein levels were measured by reverse transcription quantitative polymerase chain reaction and western blot analysis, respectively. FGFR2 was observed to be overexpressed in cancer tissues of patients with NPC and in the NPC SUNE1, C666‑1, 6‑10B and HNE‑3 cell lines, and resulted in an unfavorable prognosis. Cisplatin treatment decreased cell viability and increased FGFR2 expression. The silencing of FGFR2 was demonstrated to augment the effects of cisplatin treatment, including decreasing the cell viability and inducing cell cycle arrest, which involved the increase and decrease of the durations of G1 and S phases, respectively, and a decrease in the expression levels of cyclin D1 and CDC25A, and increasing the rate of apoptosis via the intrinsic apoptosis pathway, as demonstrated by the upregulation of cleaved caspase‑3 and B‑cell lymphoma 2 (Bcl‑2)‑associated X protein and downregulation of Bcl‑2, in SUNE1 and C666‑1 cell lines. FGFR2 was overexpressed in the cancer tissues of patients with NPC and in NPC cell lines, resulting in an unfavorable prognosis. The downregulation of FGFR2 decreased cell viability via cell cycle arrest at G1 phase, and increased the efficacy of the cisplatin‑based induction of apoptosis through the intrinsic apoptosis pathway.

Bemarituzumab with modified FOLFOX6 for advanced FGFR2-positive gastroesophageal cancer: FIGHT Phase III study design

Bemarituzumab is an afucosylated monoclonal antibody against FGFR2b (a FGF receptor) with demonstrated monotherapy clinical activity in patients with late-line gastric cancer whose tumors overexpress FGFR2b (NCT02318329). We describe the rationale and design of the FIGHT trial (NCT03343301), a global, randomized, double-blind, placebo-controlled Phase III study evaluating the role of bemarituzumab in patients with previously untreated, FGFR2b-overexpressing advanced gastroesophageal cancer. Patients are randomized in a blinded fashion to the combination of mFOLFOX6 and bemarituzumab or mFOLFOX6 and placebo. Eligible patients are selected based on the presence of either FGFR2b protein overexpression determined by immunohistochemistry or FGFR2 gene amplification determined by circulating tumor DNA. The primary end point is overall survival, and secondary end points include progression-free survival, objective response rate and safety.

A novel pretherapeutic gene expression-based risk score for treatment guidance in gastric cancer

Background

Perioperative chemotherapy is an established treatment of advanced gastric cancer patients. Treatment selection is based on clinical staging (cT). We aimed to establish and validate a prognostic score including clinical and molecular factors, to optimize treatment decisions for these patients.

Patients and methods

We analyzed 626 carcinomas of the stomach and of the gastro-esophageal junction from two academic centers including primarily resected and pre-/perioperatively treated patients. Patients were divided into a training (N = 269) and validation (N = 357) set. Expression of 11 target genes was measured by quantitative PCR in resected tumors. A risk score to predict overall survival (OS) was generated and validated. Intra-tumoral heterogeneity was assessed by analyzing 50 tumor areas from 10 patients.

Results

A risk score including the expression of CCL5, CTNNB1, EXOSC3 and LZTR1 and the clinical parameters cT, tumor localization and histopathologic type suggested two groups with a significant difference in OS [hazard ratio (HR) 0.30; 95% confidence interval (CI) 0.17-0.52]. The risk score was successfully validated in an independent cohort (HR 0.32; 95% CI 0.21-0.51; P < 0.001) as well as in subgroups of primarily resected (HR 0.30; 95% CI 0.17-0.54; P < 0.001) and pre-/perioperatively treated patients (HR 0.37; 95% CI 0.17-0.81; P = 0.009). A significant difference in OS of high- and low-risk patients was also found in primarily resected patients with intestinal (HR 0.45; 95% CI 0.23-0.90; P = 0.020) and nonintestinal-type carcinomas (HR 0.1; 95% CI 0.02-0.42; P < 0.001). Intra-tumor heterogeneity analysis indicated a classification reliability of 95% for a supposed analysis of three biopsies.

Conclusion

The identified risk score could substantially contribute to an improved management of gastric cancer patients in the context of perioperative chemotherapy.

Augmentation of Nab-Paclitaxel Chemotherapy Response by Mechanistically Diverse Antiangiogenic Agents in Preclinical Gastric Cancer Models

Gastric adenocarcinoma (GAC) remains the third most common cause of cancer-related deaths worldwide. Systemic chemotherapy is commonly recommended as a fundamental treatment for metastatic GAC; however, standard treatment has not been established yet. Angiogenesis plays a crucial role in the progression and metastasis of GAC. We evaluated therapeutic benefits of mechanistically diverse antiangiogenic agents in combination with nab-paclitaxel, a next-generation taxane, in preclinical models of GAC. Murine survival studies were performed in peritoneal dissemination models, whereas tumor growth studies were performed in subcutaneous GAC cell-derived or patient-derived xenografts. The mechanistic evaluation involved IHC and Immunoblot analysis in tumor samples. Nab-paclitaxel increased animal survival that was further improved by the addition of antiangiogenic agents ramucirumab (or its murine version DC101), cabozantinib and nintedanib. Nab-paclitaxel combination with nintedanib was most effective in improving animal survival, always greater than 300% over control. In cell-derived subcutaneous xenografts, nab-paclitaxel reduced tumor growth while all three antiangiogenic agents enhanced this effect, with nintedanib demonstrating the greatest inhibition. Furthermore, in GAC patient-derived xenografts the combination of nab-paclitaxel and nintedanib reduced tumor growth over single agents alone. Tumor tissue analysis revealed that ramucirumab and cabozantinib only reduced tumor vasculature, whereas nintedanib in addition significantly reduced tumor cell proliferation and increased apoptosis. Effects of nab-paclitaxel, a promising chemotherapeutic agent for GAC, can be enhanced by new-generation antiangiogenic agents, especially nintedanib. The data suggest that nab-paclitaxel combinations with multitargeted antiangiogenic agents carry promising potential for improving clinical GAC therapy. Mol Cancer Ther; 17(11); 2353-64. ©2018 AACR.

FGFR3 mRNA overexpression defines a subset of oligometastatic colorectal cancers with worse prognosis

Objectives

Metastatic colorectal cancer (CRC) remains a leading cause of cancer related deaths. Patients with oligometastatic liver disease represent a clinical subgroup with heterogeneous course. Until now, biomarkers to characterize outcome and therapeutic options have not been fully established.

Methods

We investigated the prevalence of FGFR alterations in a total of 140 primary colorectal tumors and 63 liver metastases of 55 oligometastatic CRC patients. FGF receptors (FGFR1-4) and their ligands (FGF3, 4 and 19) were analyzed for gene amplifications and rearrangements as well as for RNA overexpression in situ. Results were correlated with clinico-pathologic data and molecular subtypes.

Results

Primary tumors showed FGFR1 (6.3%) and FGF3,4,19 (2.2%) amplifications as well as FGFR1 (10.1%), FGFR2 (5.5%) and FGFR3 (16.2%) overexpression. In metastases, we observed FGFR1 amplifications (4.8%) as well as FGFR1 (8.5%) and FGFR3 (14.9%) overexpression. Neither FGFR2-4 amplifications nor gene rearrangements were observed. FGFR3 overexpression was significantly associated with shorter overall survival in metastases (mOS 19.9 vs. 47.4 months, HR=3.14, p=0.0152), but not in primary CRC (HR=1.01, p=0.985). Although rare, also FGFR1 amplification was indicative of worse outcome (mOS 12.6 vs. 47.4 months, HR=8.83, p=0.00111).

Conclusions

We provide the so far most comprehensive analysis of FGFR alterations in primary and metastatic CRC. We describe FGFR3 overexpression in 15% of CRC patients with oligometastatic liver disease as a prognosticator for poor outcome. Recently FGFR3 overexpression has been shown to be a potential therapeutic target. Therefore, we suggest focusing on this subgroup in upcoming clinical trials with FGFR-targeted therapies.

Future applications of FGF/FGFR inhibitors in cancer

INTRODUCTION

Deregulation of the fibroblast growth factor (FGF)/FGF receptor (FGFR) network occurs frequently in tumors due to gene amplification, activating mutations, and oncogenic fusions. Thus, the development of FGF/FGFR-targeting therapies is the focus of several basic, preclinical, and clinical studies. Areas covered: This review will recapitulate the status of current FGF/FGFR-targeted drugs. Expert commentary: Non-selective FGF/FGFR inhibitors have been approved for cancer treatment but evidence highlights various complications affecting their use in the clinical practice. It appears mandatory to identify FGF/FGFR alterations and appropriate biomarkers that may predict and monitor response to treatment, to establish the contribution of the FGF/FGFR system to the onset of mechanisms of drug resistance, and to develop effective combinations of FGF/FGFR inhibitors with other targeted therapies.

Genomic Profiling of HER2-Positive Gastric Cancer: PI3K/Akt/mTOR Pathway as Predictor of Outcomes in HER2-Positive Advanced Gastric Cancer Treated with Trastuzumab

BACKGROUND

HER2-positive gastric cancer (GC) affects 7%-34% of patients with GC. Trastuzumab-based first-line treatment has become the standard of care for HER2-positive advanced gastric cancer (AGC). However, there are no clinically validated biomarkers for resistance to HER2-targeted therapies. Upregulation of PI3K pathway and tyrosine kinase receptor (TKR) alterations have been noted as molecular mechanisms of resistance in breast cancer. Our study aimed to perform a molecular characterization of HER2-positive AGC and investigate the role of PI3K/Akt/mTOR signaling pathway activation and TKR gene copy number (GCN) gains as predictive biomarkers in HER2-positive AGC treated with trastuzumab.

PATIENTS AND METHODS

Forty-two HER2-positive GC samples from patients treated with trastuzumab-based first-line chemotherapy were selected. DNA samples were sequenced. PTEN and MET immunohistochemistry were also performed.

RESULTS

Concurrent genetic alterations were detected in 97.1% of HER2-positive AGC. We found activation of PI3K/Akt/mTOR pathway in 52.4% of patients and TKR GCN gains in 38.1%. TKR GCN gains did not correlate with overall survival (OS) or progression-free survival (PFS). Multivariate Cox models showed that PI3K/Akt/mTOR activation negatively affects the effectiveness of trastuzumab-based chemotherapy in terms of OS and PFS.

CONCLUSION

Our results provide for the first time a detailed molecular profile of concurrent genetic alterations in HER2-positive AGC. PI3K pathway activation could be used as a predictive marker of worse outcome in this patient population. In addition, gains in copy number of other TKR genes in this subgroup may also influence the survival benefit obtained with trastuzumab.

IMPLICATIONS FOR PRACTICE

This article reports, for the first time, a detailed molecular profile of genomic alterations in patients with HER2-positive advanced gastric cancer (AGC). PI3K/Akt/mTOR signaling pathway activation seems to have a differentially negative effect on overall survival and progression-free survival in AGC treated with trastuzumab-based chemotherapy. Combining different targeted agents could be a successful therapeutic strategy to improve the prognosis of HER2-positive AGC.

A randomized, open-label study of the efficacy and safety of AZD4547 monotherapy versus paclitaxel for the treatment of advanced gastric adenocarcinoma with FGFR2 polysomy or gene amplification

Background

Approximately 5%-10% of gastric cancers have a fibroblast growth factor receptor-2 (FGFR2) gene amplification. AZD4547 is a selective FGFR-1, 2, 3 tyrosine kinase inhibitor with potent preclinical activity in FGFR2 amplified gastric adenocarcinoma SNU16 and SGC083 xenograft models. The randomized phase II SHINE study (NCT01457846) investigated whether AZD4547 improves clinical outcome versus paclitaxel as second-line treatment in patients with advanced gastric adenocarcinoma displaying FGFR2 polysomy or gene amplification detected by fluorescence in situ hybridization.

Patients and methods

Patients were randomized 3:2 (FGFR2 gene amplification) or 1:1 (FGFR2 polysomy) to AZD4547 or paclitaxel. Patients received AZD4547 80 mg twice daily, orally, on a 2 weeks on/1 week off schedule of a 21-day cycle or intravenous paclitaxel 80 mg/m2 administered weekly on days 1, 8, and 15 of a 28-day cycle. The primary end point was progression-free survival (PFS). Safety outcomes were assessed and an exploratory biomarker analysis was undertaken.

Results

Of 71 patients randomized (AZD4547 n = 41, paclitaxel n = 30), 67 received study treatment (AZD4547 n = 40, paclitaxel n = 27). Among all randomized patients, median PFS was 1.8 months with AZD4547 and 3.5 months with paclitaxel (one-sided P = 0.9581); median follow-up duration for PFS was 1.77 and 2.12 months, respectively. The incidence of adverse events was similar in both treatment arms. Exploratory biomarker analyses revealed marked intratumor heterogeneity of FGFR2 amplification and poor concordance between amplification/polysomy and FGFR2 mRNA expression.

Conclusions

AZD4547 did not significantly improve PFS versus paclitaxel in gastric cancer FGFR2 amplification/polysomy patients. Considerable intratumor heterogeneity for FGFR2 gene amplification and poor concordance between FGFR2 amplification/polysomy and FGFR2 expression indicates the need for alternative predictive biomarker testing. AZD4547 was generally well tolerated.

Complementary utility of targeted next-generation sequencing and immunohistochemistry panels as a screening platform to select targeted therapy for advanced gastric cancer

We tested the clinical utility of combined profiling of Ion Torrent PGM based next-generation sequencing (NGS) and immunohistochemistry (IHC) for assignment to molecularly targeted therapies. A consecutive cohort of 93 patients with advanced/metastatic GC who underwent palliative chemotherapy between March and December 2015 were prospectively enrolled. Formalin fixed paraffin embedded tumor biopsy specimens were subjected to a 10 GC panels [Epstein Barr virus encoding RNA in-situ hybridization, IHC for mismatch repair proteins (MMR; MLH1, PMS2, MSH2, and MSH6), receptor tyrosine kinases (HER2, EGFR, and MET), PTEN, and p53 protein], and a commercial targeted NGS panel of 52 genes (Oncomine Focus Assay). Treatment was based on availability of targeted agents at the time of molecular diagnosis. Among the 81 cases with available tumor samples, complete NGS and IHC profiles were successfully achieved in 66 cases (81.5%); only IHC results were available for 15 cases. Eight cases received matched therapy based on sequencing results; ERBB2 amplification, trastuzumab (n = 4); PIK3CA mutation, Akt inhibitor (n = 2); and FGFR2 amplification, FGFR2b inhibitor (n = 2). Eleven cases received matched therapy based on IHC; ERBB2 positivity, trastuzumab (n = 5); PTEN loss (n = 2), PI3Kβ inhibitor; MMR deficiency (n = 2), PD-1 inhibitor; and EGFR positivity (n = 2), pan-ERBB inhibitor. A total of 19 (23.5%) and 62 (76.5%) cases were treated with matched and non-matched therapy, respectively. Matched therapy had significantly higher overall response rate than non-matched therapy (55.6% vs 13.1%, P = 0.001). NGS and IHC markers provide complementary utility in identifying patients who may benefit from targeted therapies.

Biomarker-driven targeted therapies for gastric/gastro-esophageal junction malignancies

Gastroesophageal malignancies often contain high amounts of genetic and molecular alterations that result in an aggressive disease capable of rapidly metastasizing to distant organs and early development of drug resistance. Most patients in the Western hemisphere present with locally advanced or metastatic disease that is treated with systemic chemotherapy used either in the neoadjuvant or palliative setting, respectively. This article will review the various recent advances in the development of targeted therapies for the treatment of advanced gastric and gastroesophageal cancer.

Prognostic impact of fibroblast growth factor receptor 2 gene amplification in patients receiving fluoropyrimidine and platinum chemotherapy for metastatic and locally advanced unresectable gastric cancers

Although Fibroblast growth factor receptor (FGFR) 2 gene amplification and its prognostic significance have been reported in resectable gastric cancers, information on these features remains limited in the metastatic setting. The presence of FGFR2 amplification was assessed in formalin-fixed, paraffin-embedded tissues using a quantitative PCR-based gene copy number assay with advanced gastric cancer cohorts. A total of 327 patients with tumor portion of ≥70% were analyzed for clinical features. Among these patients, 260 who received first-line fluoropyrimidine and platinum chemotherapy were analyzed for survival.Sixteen of 327 patients (4.9%) exhibited FGFR2 amplification. The amplification group showed associations with age <65 years, Borrmann type 4 disease, poor performance status, poorly differentiated histology, extra-abdominal lymph node metastases, and bone metastases. The median overall survival (OS) and progression-free survival (PFS) were found to be 12.7 and 5.8 months, respectively. In univariate analysis, PFS did not differ between amplification and no amplification groups (hazard ratio [HR]=1.34, 95% confidence interval [CI]: 0.78-2.31, p=0.290), although the OS was significantly shorter in the amplification group (HR=1.92, 95% CI: 1.13-3.26, p=0.015). However, multivariate analysis indicated that FGFR2 amplification was not an independent prognostic factor for OS (HR=1.42, 95% CI: 0.77-2.61, p=0.261).Although FGFR2 amplification is associated with poorer OS, it does not appear to be an independent prognostic predictor in patients with advanced gastric cancer treated with palliative fluoropyrimidine and platinum chemotherapy.

In situ analysis of FGFR2 mRNA and comparison with FGFR2 gene copy number by dual-color in situ hybridization in a large cohort of gastric cancer patients

BACKGROUND

Fibroblast growth factor receptor (FGFR2) has been proposed as a target in gastric cancer. However, appropriate methods to select patients for anti-FGFR2 therapies have not yet been established.

METHODS

We used in situ techniques to investigate FGFR2 mRNA expression and gene amplification in a large cohort of 1036 Japanese gastric cancer patients. FGFR2 mRNA expression was determined by RNAscope. FGFR2 gene amplification was determined by dual-color in situ hybridization (DISH).

RESULTS

We successfully analyzed 578 and 718 samples by DISH and RNAscope, respectively; 2% (12/578) showed strong FGFR2 gene amplification (FGFR2:CEN10 >10); moderate FGFR2 gene amplification (FGFR2:CEN10 <10; ≥2) was detected in 8% (47/578); and high FGFR2 mRNA expression of score 4 (>10 dots/cell and >10% of positive cells with dot clusters under a 20× objective) was seen in 4% (29/718). For 468 samples, both mRNA and DISH data were available. FGFR2 mRNA expression levels were associated with gene amplification; FGFR2 mRNA levels were highest in the highly amplified samples (n = 12). All highly amplified samples showed very strong FGFR2 mRNA expression (dense clusters of the signal visible under a 1× objective). Patients with very strong FGFR2 mRNA expression showed more homogeneous FGFR2 mRNA expression compared to patients with lower FGFGR2 mRNA expression. Gastric cancer patients with tumors that had an FGFR2 mRNA expression score of 4 had shorter RFS compared with score 0-3 patients.

CONCLUSION

RNAscope and DISH are suitable methods to evaluate FGFR2 status in gastric cancer. Formalin-fixed paraffin-embedded (FFPE) tissue slides allowed evaluation of the intratumor heterogeneity of these FGFR2 biomarkers.

Fibroblast growth factor receptor 2 expression, but not its genetic amplification, is associated with tumor growth and worse survival in esophagogastric junction adenocarcinoma

Background

Fibroblast growth factor receptor 2 (FGFR2) genetic alterations lead to tumor cell proliferation in various types of cancer. We hypothesized that FGFR2 amplification is associated with FGFR2 expression, resulting in tumor growth and poorer outcome in esophagogastric junction (EGJ) adenocarcinoma.

Patients and Methods

A total of 176 consecutive chemo-naive patients with EGJ adenocarcinoma were enrolled from two academic institutions. FGFR2 amplification was examined by real-time PCR (N = 140) and FGFR2 expression with immunohistochemical staining (N = 176), and compared against clinicopathological factors and patient outcomes. The effects of FGFR2 inhibition or overexpression on cell proliferation, cell cycle, and apoptosis assays were investigated in EGJ adenocarcinoma cell lines. Downstream FGFR2, AKT and ERK were also examined.

Results

Based on the correlation between FGFR2 levels and FGFR2 overexpression in vitro, FGFR2 amplification was defined as copy number > 3.0. In clinical samples, FGFR2 amplification and FGFR2 IHC expression were 15% and 61%, respectively. Although these two statuses were significantly correlated (P < 0.05), only FGFR2 IHC expression was significantly associated with tumor depth (multivariate P < 0.001) and overall survival of patients (univariate P = 0.007). Supporting these findings, FGFR2 overexpression was associated with tumor cell proliferation, cell cycle progression, and anti-apoptosis. Selective inhibition of FGFR2 sufficiently suppressed tumor cell proliferation through de-phosphorylation of AKT and ERK.

Conclusions

FGFR2 amplification was significantly associated with FGFR2 expression. FGFR2 expression (but not FGFR2 amplification) was associated with tumor growth and patient outcomes. Our findings support FGFR2 as a novel therapeutic target for EGJ adenocarcinoma.

FGFR2 amplification in colorectal adenocarcinoma

FGFR2 is recurrently amplified in 5% of gastric cancers and 1%–4% of breast cancers; however, this molecular alteration has never been reported in a primary colorectal cancer specimen. Preclinical studies indicate that several FGFR tyrosine-kinase inhibitors (TKIs), such as AZD4547, have in vitro activity against the FGFR2-amplified colorectal cell line, NCI-H716. The efficacy of these inhibitors is currently under investigation in clinical trials for breast and gastric cancer. Thus, better characterizing colorectal tumors for FGFR2 amplification could identify a subset of patients who may benefit from FGFR TKI therapies. Here, we describe a novel FGFR2 amplification identified by clinical next-generation sequencing in a primary colorectal cancer. Further characterization of the tumor by immunohistochemistry showed neuroendocrine differentiation, similar to the reported properties of the NCI-H716 cell line. These findings demonstrate that the spectrum of potentially clinically actionable mutations detected by targeted clinical sequencing panels is not limited to only single-nucleotide polymorphisms and insertions/deletions but also to copy-number alterations.

[Effect of basic fibroblast growth factor antibody combined with irinotecan on proliferation and apoptosis of small cell lung cancer H223 cells in vitro]

OBJECTIVE

To study the synergistic inhibitory effects of basic fibroblast growth factor (bFGF) monoclonal antibody (bFGF mAb) and irinotecan on the proliferation of small cell lung cancer H223 cells.

METHODS

CCK-8 assay and flow cytometry were used to assess the effects of bFGF mAb combined with irinotecan on the proliferation and apoptosis of H223 cells, respectively. Western blotting was performed to analyze the effect of bFGF-mAb combined with irinotecan on AKT and ERK1/2 phosphorylation in the cells.

RESULTS

Both bFGF mAb and irinotecan alone inhibited H223 cell proliferation in a dose-dependent manner (P<0.05). The inhibitory rate was significantly higher in H223 cells treated with bFGF mAb + irinotecan (54.30%) than in cell treated with bFGF mAb (18.73%) or irinotecan (21.96%) alone (P<0.05). Both bFGF mAb and irinotecan induced H223 cell apoptosis in a dose-dependent manner (P<0.05), and the combined treatment resulted in a significantly higher early apoptosis rates (6.5%) than treatment with bFGF mAb (2.7%) or irinotecan (4.3%) alone (P<0.05). bFGF mAb and irinotecan, either alone or in combination, significantly inhibited the levels of p-AKT protein and p-ERK1/2 protein without obviously affecting AKT and ERK1/2 protein levels.

CONCLUSION

bFGF mAb and irinotecan produce synergistic inhibitory effects on small cell lung cancer H223 cells by suppressing proliferation and promoting apoptosis of the cells, and can effectively block the MAPK/ERK and PI3K/AKT signaling pathways associated with bFGF.

Pathogenesis of Gastric Cancer: Genetics and Molecular Classification

Gastric cancer is the fifth most incident and the third most common cause of cancer-related death in the world. Infection with Helicobacter pylori is the major risk factor for this disease. Gastric cancer is the final outcome of a cascade of events that takes decades to occur and results from the accumulation of multiple genetic and epigenetic alterations. These changes are crucial for tumor cells to expedite and sustain the array of pathways involved in the cancer development, such as cell cycle, DNA repair, metabolism, cell-to-cell and cell-to-matrix interactions, apoptosis, angiogenesis, and immune surveillance. Comprehensive molecular analyses of gastric cancer have disclosed the complex heterogeneity of this disease. In particular, these analyses have confirmed that Epstein-Barr virus (EBV)-positive gastric cancer is a distinct entity. The identification of gastric cancer subtypes characterized by recognizable molecular profiles may pave the way for a more personalized clinical management and to the identification of novel therapeutic targets and biomarkers for screening, prognosis, prediction of response to treatment, and monitoring of gastric cancer progression.

Prognostic role of fibroblast growth factor receptor 2 in human solid tumors: A systematic review and meta-analysis

In the past decades, the oncogenic role of fibroblast growth factor receptor 2 has been demonstrated in a number of cancer types. However, studies have reported contradictory findings concerning the correlation between fibroblast growth factor receptor 2 expression and prognosis in solid tumors. To address this discrepancy, we performed a meta-analysis with 18 published studies (2975 patients) retrieved from PubMed, EMBASE, and Web of science. Data were extracted and computed into odds ratios. The results showed that fibroblast growth factor receptor 2 overexpression was significantly associated with decreased 3-year overall survival (odds ratio = 1.93, 95% confidence interval: 1.30-2.85, p = 0.001) and 5-year overall survival (odds ratio = 1.62, 95% confidence interval: 1.07-2.44, p = 0.02) in patients with solid tumors. Subgroup analysis revealed that high fibroblast growth factor receptor 2 expression was also associated with poor prognosis of gastric cancer, hepatocellular carcinoma, and esophageal cancer, but not correlated with pancreatic cancer. In conclusion, fibroblast growth factor receptor 2 overexpression is correlated with decreased survival in most solid tumors, suggesting that the expression status of fibroblast growth factor receptor 2 is a valuable prognostic biomarker and a novel therapeutic target in human solid tumors.