Fibroblast Growth Factor (FGF) Receptor/FGF Inhibitors: Novel Targets and Strategies for Optimization of Response of Solid Tumors

Design, synthesis, and biological evaluation of selective covalent inhibitors of FGFR4

Aberrant signaling via fibroblast growth factor 19 (FGF19)/fibroblast growth factor receptor 4 (FGFR4) has been identified as a driver of tumorigenesis and the development of many solid tumors, making FGFR4 is a promising target for anticancer therapy. Herein, we designed and synthesized a series of bis-acrylamide covalent FGFR4 inhibitors and evaluated their inhibitory activity against FGFRs, FGFR4 mutants, and their antitumor activity. CXF-007, verified by mass spectrometry and crystal structures to form covalent bonds with Cys552 of FGFR4 and Cys488 of FGFR1, exhibited stronger selectivity and potent inhibitory activity for FGFR4 and FGFR4 cysteine mutants. Moreover, CXF-007 exhibited significant antitumor activity in hepatocellular carcinoma cell lines and breast cancer cell lines through sustained inhibition of the FGFR4 signaling pathway. In summary, our study highlights a novel covalent FGFR4 inhibitor, CXF-007, which has the potential to overcome drug-induced FGFR4 mutations and might provide a new strategy for future anticancer drug discovery.

The Application of Artificial Intelligence and Drug Repositioning for the Identification of Fibroblast Growth Factor Receptor Inhibitors: A Review

Artificial intelligence talks about modeling intelligent behavior through a computer with the least human involvement. Drug repositioning techniques based on artificial intelligence accelerate the research process and decrease the cost of experimental studies. Dysregulation of fibroblast growth factor (FGF) receptors as the tyrosine kinase family of receptors plays a vital role in a wide range of malignancies. Because of their functional significance, they were considered promising drug targets for the therapy of various cancers. This review has summarized small molecules capable of inhibiting FGF receptors that progressed using artificial intelligence and repositioning drugs examined in clinical trials associated with cancer therapy. This review is based on a literature search in PubMed, Web of Science, Scopus EMBASE, and Google Scholar databases to gather the necessary information in each chapter by employing keywords like artificial intelligence, computational drug design, drug repositioning, and FGF receptor inhibitors. To achieve this goal, a spacious literature review of human studies in these fields-published over the last 20 decades-was performed. According to published reports, nonselective FGF receptor inhibitors can be used for cancer management, and multitarget kinase inhibitors are the first drug class approved due to more advanced clinical studies. For example, AZD4547 and BGJ398 are gradually entering the consumption cycle and are good options as combined treatments. Artificial intelligence and drug repositioning methods can help preselect suitable drug targets more successfully for future inhibition of carcinogenicity.

Diagnostic, Prognostic, and Therapeutic Role for Angiogenesis Markers in Head and Neck Squamous Cell Carcinoma: A Narrative Review

Despite refinements to diagnostic and therapeutic approaches over the last two decades, the outcome of patients with head and neck squamous cell carcinoma (HNSCC) has not shown substantial improvements, especially regarding those with advanced-stage disease. Angiogenesis is believed to be a turning point in the development of solid tumors, being a premise for mass growth and potential distant dissemination. Cancer-induced angiogenesis is a result of increased expression of angiogenic factors, decreased expression of anti-angiogenic factors, or a combination of both. The assessment of angiogenesis has also emerged as a potentially useful biological prognostic and predictive factor in HNSCC. The aim of this review is to assess the level of current knowledge on the neo-angiogenesis markers involved in the biology, behavior, and prognosis of HNSCC. A search (between 1 January 2012 and 10 October 2022) was run in PubMed, Scopus, and Web of Science electronic databases. After full-text screening and application of inclusion/exclusion criteria, 84 articles are included. The current knowledge and debate on angiogenesis in HNSCC presented in the eligible articles are stratified as follows: (i) diagnostic markers; (ii) prognostic markers; (iii) predictive markers; and (iv) markers with a potential therapeutic role. Angiogenesis is a biological and pathological indicator of malignancies progression and has negative implications in prognosis of some solid tumors; several signals capable of tripping the "angiogenic switch" have also been identified in HNSCC. Although several studies suggested that antiangiogenic agents might be a valuable adjunct to conventional chemo-radiation of HNSCC, their long-term therapeutic value remains uncertain. Further investigations are required on combinations of antiangiogenic agents with conventional chemotherapeutic ones, immunotherapeutic and molecularly targeted agents in HNSCC. Additional data are necessary to pinpoint which patients could benefit most from these treatments.

The Role of Genetic Mutations in Mitochondrial-Driven Cancer Growth in Selected Tumors: Breast and Gynecological Malignancies

There is an increasing understanding of the molecular and cytogenetic background of various tumors that helps us better conceptualize the pathogenesis of specific diseases. Additionally, in many cases, these molecular and cytogenetic alterations have diagnostic, prognostic, and/or therapeutic applications that are heavily used in clinical practice. Given that there is always room for improvement in cancer treatments and in cancer patient management, it is important to discover new therapeutic targets for affected individuals. In this review, we discuss mitochondrial changes in breast and gynecological (endometrial and ovarian) cancers. In addition, we review how the frequently altered genes in these diseases (BRCA1/2, HER2, PTEN, PIK3CA, CTNNB1, RAS, CTNNB1, FGFR, TP53, ARID1A, and TERT) affect the mitochondria, highlighting the possible associated individual therapeutic targets. With this approach, drugs targeting mitochondrial glucose or fatty acid metabolism, reactive oxygen species production, mitochondrial biogenesis, mtDNA transcription, mitophagy, or cell death pathways could provide further tailored treatment.

FORT-1: Phase II/III Study of Rogaratinib Versus Chemotherapy in Patients With Locally Advanced or Metastatic Urothelial Carcinoma Selected Based on FGFR1/3 mRNA Expression

PURPOSE

Rogaratinib, an oral pan-fibroblast growth factor receptor (FGFR1-4) inhibitor, showed promising phase I efficacy and safety in patients with advanced urothelial carcinoma (UC) with FGFR1-3 mRNA overexpression. We assessed rogaratinib efficacy and safety versus chemotherapy in patients with FGFR mRNA-positive advanced/metastatic UC previously treated with platinum chemotherapy.

METHODS

FORT-1 (ClinicalTrials.gov identifier: NCT03410693) was a phase II/III, randomized, open-label trial. Patients with FGFR1/3 mRNA-positive locally advanced or metastatic UC with ≥ 1 prior platinum-containing regimen were randomly assigned (1:1) to rogaratinib (800 mg orally twice daily, 3-week cycles; n = 87) or chemotherapy (docetaxel 75 mg/m2, paclitaxel 175 mg/m2, or vinflunine 320 mg/m2 intravenously once every 3 weeks; n = 88). The primary end point was overall survival, with objective response rate (ORR) analysis planned following phase II accrual. Because of comparable efficacy between treatments, enrollment was stopped before progression to phase III; a full interim analysis of phase II was completed.

RESULTS

ORRs were 20.7% (rogaratinib, 18/87; 95% CI, 12.7 to 30.7) and 19.3% (chemotherapy, 17/88; 95% CI, 11.7 to 29.1). Median overall survival was 8.3 months (95% CI, 6.5 to not estimable) and 9.8 months (95% CI, 6.8 to not estimable; hazard ratio, 1.11; 95% CI, 0.71 to 1.72; P = .67). Grade 3/4 events occurred in 37 (43.0%)/4 (4.7%) patients and 32 (39.0%)/15 (18.3%), respectively. No rogaratinib-related deaths occurred. Exploratory analysis of patients with FGFR3 DNA alterations showed ORRs of 52.4% (11/21; 95% CI, 29.8 to 74.3) for rogaratinib and 26.7% (4/15; 95% CI, 7.8 to 55.1) for chemotherapy.

CONCLUSION

To our knowledge, these are the first data to compare FGFR-directed therapy with chemotherapy in patients with FGFR-altered UC, showing comparable efficacy and manageable safety. Exploratory testing suggested FGFR3 DNA alterations in association with FGFR1/3 mRNA overexpression may be better predictors of rogaratinib response.

Antitumor effect of memantine is related to the formation of the splicing isoform of GLG1, a decoy FGF‑binding protein

Drug repositioning is a strategy for repurposing the approved or investigational drugs that are outside the scope of the original medical indication. Memantine is used as a non‑competitive N‑methyl‑D‑aspartate receptor antagonist to prevent glutamate‑mediated excitotoxicity in Alzheimer's disease, and is one of the promising agents which is utilized for the purpose of cancer therapy. However, the association between memantine and Golgi glycoprotein 1 (GLG1), an intracellular fibroblast growth factor receptor, in cancers has not yet been clarified. The present study analyzed the expression and location of GLG1 in tumor cells treated with memantine. Memantine was found to suppress the growth of malignant glioma and breast cancer cells in a concentration‑dependent manner. The mRNA expression of GLG1 was upregulated in a concentration‑dependent manner, and the splicing variant profiles were altered in all cell lines examined. The results of western blot analysis revealed an increase in the full‑length and truncated forms of GLG1. Moreover, GLG1 spread in the cytosol of memantine‑treated cells, whereas it localized in the Golgi apparatus in control cells. Since GLG1 functions as a decoy FGF receptor, the modulation of GLG1 may prove to be one of the mechanisms underlying the cancer‑suppressive effects of memantine.

Intra-tumoral FGFR2 Expression Predicts Prognosis and Chemotherapy Response in Advanced HER2-positive Gastric Cancer Patients

BACKGROUND/AIM

This study aimed to evaluate the relationship between clinical outcomes and intra-tumoral fibroblast growth factor receptor 2 (FGFR2) expression in human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC) patients who had undergone HER2-targeted chemotherapy.

PATIENTS AND METHODS

A retrospective analysis was performed in 22 patients with HER2-positive GC, who had undergone systemic chemotherapy. We performed immunohistochemistry staining of FGFR2 expression using surgically resected specimens or biopsied samples and evaluated clinicopathological characteristic and overall survival (OS) in the FGFR2-negative and -positive GC groups.

RESULTS

A total of 8 and 14 patients were placed in the FGFR2-negative and -positive group, respectively. The median OS rates were 56.2 and 16.0 months in the FGFR2-negative and -positive groups, respectively. The FGFR2-negative group had a significantly better prognosis after HER2-targeted chemotherapy [p=0.027 (log-rank test)]. The univariate analysis revealed that performing gastrectomy, response to combination chemotherapy with trastuzumab, and FGFR2 positivity were significantly correlated with OS. In a multivariate analysis, the response to combination chemotherapy with trastuzumab (p=0.008) was significantly correlated with OS. In addition, the proportions of patients who showed CR or PR in response to chemotherapy were 87.5 and 42.9% in the FGFR2-negative and -positive groups, respectively (p=0.031).

CONCLUSION

HER2-positive GC patients, without overexpression of FGFR2, exhibited an improved prognosis and response rate to trastuzumab combination chemotherapy. Assessment of intra-tumoral FGFR2 expression could be helpful in predicting the prognosis and response to trastuzumab in HER2-positive GC patients.

High-intermediate risk endometrial cancer: moving toward a molecularly based risk assessment profile

In the USA, endometrial cancer (EMCA) incidence is increasing as the risk factors of obesity, diabetes, and hypertension become more prevalent. Although most EMCA is detected at an early stage and surgical intervention is curative, a subset of patients termed 'high-intermediate risk' (H-IR) experience an increased rate of recurrence. Unfortunately, adjuvant therapies in patients with H-IR EMCA have yet to increase overall survival. Historically, stratification of these patients from their low-risk counterparts incorporated clinical and pathologic findings. However, due to developments in molecular testing and genomic sequencing, tumor biomarkers are now being incorporated into the risk-assessment criteria in the hope of finding molecular profile(s) that could highlight treatment regimens that will increase patient survival. Since modern research aims to accurately identify patients with a higher risk of recurrence and develop effective interventions to improve patient survival, these molecular-based analyses could allow for an enhanced understanding of a patient's true risk of recurrence to facilitate the rise of personalized medicine. This review summarizes key clinical trials and recent advances in molecular and genomic profiles that have influenced current treatment regimens for patients with H-IR EMCA and laid the foundation for subsequent research.

Immunomodulation via FGFR inhibition augments FGFR1 targeting T-cell based antitumor immunotherapy for head and neck squamous cell carcinoma

Fibroblast growth factor receptor 1 (FGFR1) is overexpressed in multiple types of solid tumors, including head and neck squamous cell carcinoma (HNSCC). Being associated with poor prognosis, FGFR1 is a potential therapeutic target for aggressive tumors. T cell-based cancer immunotherapy has played a central role in novel cancer treatments. However, the potential of antitumor immunotherapy targeting FGFR1 has not been investigated. Here, we showed that FGFR-tyrosine kinase inhibitors (TKIs) augmented antitumor effects of immune checkpoint inhibitors in an HNSCC mouse model and upregulated tumoral MHC class I and MHC class II expression in vivo and in vitro. This upregulation was associated with the mitogen-activated protein kinase signaling pathway, which is a crucial pathway for cancer development through FGFR signaling. Moreover, we identified an FGFR1-derived peptide epitope (FGFR1_305-319) that could elicit antigen-reactive and multiple HLA-restricted CD4⁺ T cell responses. These T cells showed direct cytotoxicity against tumor cells that expressed FGFR1. Notably, FGFR-TKIs augmented antitumor effects of FGFR1-reactive T cells against human HNSCC cells. These results indicate that the combination of FGFR-TKIs with immunotherapy, such as an FGFR1-targeting peptide vaccine or immune checkpoint inhibitor, could be a novel and robust immunologic approach for treating patients with FGFR1-expressing cancer cells.

High FGFR1-4 mRNA expression levels correlate with response to selective FGFR inhibitors in breast cancer

PURPOSE

FGFR1 amplification (FGFR1amp) is recurrent in metastatic breast cancer (BC) and is associated with resistance to endocrine therapy (ET) and CDK4/6 inhibitors (CDK4/6i). Multi-tyrosine kinase inhibitors (MTKI) and selective pan-FGFR inhibitors (FGFRi) are being developed for FGFR1amp BC. High-level FGFR amplification and protein expression by IHC have identified BC responders to FGFRi or MTKI, respectively.

EXPERIMENTAL DESIGN

Here, we used preclinical models and patient samples to identify predictive biomarkers to these drugs. We evaluated the antitumor activity of an FGFRi and an MTKI in a collection of seventeen BC patient-derived xenografts (PDXs) harboring amplification in FGFR1/2/3/4 and in ten patients receiving either an FGFRi/MTKI. mRNA levels were measured on FFPE tumor samples using two commercial strategies. Proliferation and angiogenesis were evaluated by detecting Ki-67 and CD31 in viable areas by immunofluorescence.

RESULTS

High FGFR1-4 mRNA levels but not copy number alteration (CNA) associated with FGFRi response. Treatment with MTKI showed higher response rates than with FGFRi (86% vs 53%), regardless of the FGFR1-4 mRNA levels. FGFR-addicted PDXs exhibited an antiproliferative response to either FGFRi or MTKI, and PDXs exclusively sensitive to MTKI exhibited an additional anti-angiogenic response. Consistently, clinical benefit of MTKI was not associated with high FGFR1-4 mRNA levels and it was observed in patients previously treated with anti-angiogenic drugs.

CONCLUSION

Tailored therapy with FGFRi in molecularly-selected metastatic BC based on high FGFR1-4 mRNA levels warrants prospective validation in luminal BC CDK4/6i-resistant patients and in TNBC patients without targeted therapeutic options.

Fibroblast growth factor and kidney disease: Updates for emerging novel therapeutics

The discovery of fibroblast growth factors (FGFs) and fibroblast growth factor receptors (FGFRs) provided a profound new insight into physiological and metabolic functions. FGF has a large family by having divergent structural elements and enable functional divergence and specification. FGF and FGFRs are highly expressed during kidney development. Signals from the ureteric bud regulate morphogenesis, nephrogenesis, and nephron progenitor survival. Thus, FGF signaling plays an important role in kidney progenitor cell aggregation at the sites of new nephron formation. This review will summarize the current knowledge about functions of FGF signaling in kidney development and their ability to promote regeneration in injured kidneys and its use as a biomarker and therapeutic target in kidney diseases. Further studies are essential to determine the predictive significance of the various FGF/FGFR deviations and to integrate them into clinical algorithms.

The phenomenon of multidrug resistance in glioblastomas

The most common and aggressive brain tumor in the adult population is glioblastoma (GBM). The lifespan of patients does not exceed 22 months. One of the reasons for the low effectiveness of GBM treatment is its radioresistance and chemoresistance. In the current review, we discuss the phenomenon of multidrug resistance of GBM in the context of the expression of ABC family transporter proteins and the mechanisms of proliferation, angiogenesis, and recurrence. We focused on the search of molecular targets among growth factors, receptors, signal transduction proteins, microRNAs, transcription factors, proto-oncogenes, tumor suppressor genes, and their single-nucleotide polymorphisms.

FGF19/SOCE/NFATc2 signaling circuit facilitates the self-renewal of liver cancer stem cells

Background & Aims: Liver cancer stem cells (LCSCs) mediate therapeutic resistance and correlate with poor outcomes in patients with hepatocellular carcinoma (HCC). Fibroblast growth factor (FGF)-19 is a crucial oncogenic driver gene in HCC and correlates with poor prognosis. However, whether FGF19 signaling regulates the self-renewal of LCSCs is unknown.

Methods: LCSCs were enriched by serum-free suspension. Self-renewal of LCSCs were characterized by sphere formation assay, clonogenicity assay, sorafenib resistance assay and tumorigenic potential assays. Ca²⁺ image was employed to determine the intracellular concentration of Ca²⁺. Gain- and loss-of function studies were applied to explore the role of FGF19 signaling in the self-renewal of LCSCs.

Results: FGF19 was up-regulated in LCSCs, and positively correlated with certain self-renewal related genes in HCC. Silencing FGF19 suppressed self-renewal of LCSCs, whereas overexpressing FGF19 facilitated CSCs-like properties via activation of FGF receptor (FGFR)-4 in none-LCSCs. Mechanistically, FGF19/FGFR4 signaling stimulated store-operated Ca²⁺ entry (SOCE) through both the PLCγ and ERK1/2 pathways. Subsequently, SOCE-calcineurin signaling promoted the activation and translocation of nuclear factors of activated T cells (NFAT)-c2, which transcriptionally activated the expression of stemness-related genes (e.g., NANOG, OCT4 and SOX2), as well as FGF19. Furthermore, blockade of FGF19/FGFR4-NFATc2 signaling observably suppressed the self-renewal of LCSCs.

Conclusions: FGF19/FGFR4 axis promotes the self-renewal of LCSCs via activating SOCE/NFATc2 pathway; in turn, NFATc2 transcriptionally activates FGF19 expression. Targeting this signaling circuit represents a potential strategy for improving the therapeutic efficacy of HCC.

Clinical relevance of oncogenic driver mutations identified in endometrial carcinoma

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Comprehensive somatic mutations profiling in endometrial carcinoma.

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Relationships between somatic mutations and clinicopathological characteristics.

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Relatiohship between FBXW7 mutation and vascular invasion in endometrial carcinoma.

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FGFR2 mutations are related with deep myometrial invasion in endometrial carcinoma.

Purpose

Endometrial carcinoma (EC) is a clinically heterogeneous disease characterized by a number of different histological subtypes, and its heterogeneity may be involved in the accumulation of multiple genetic alterations. The aim of this work was to investigate the comprehensive mutational profile of EC tumors, and examine the associations between somatic mutations and clinicopathological features or survival in EC patients.

Methods

A total of 100 surgical tumors were obtained from EC patients who had previously undergone surgery. Genomic DNA samples extracted from fresh-frozen tissues were analyzed using the Ion AmpliSeq Cancer Hotspot Panel v2 Kit, covering 50 tumor-related genes.

Results

Validated mutations were detected in 91 of the 100 tumors (91%) and identified in eight of the most frequently mutated genes, namely PTEN (57%), PIK3CA (51%), TP53 (30%), KRAS (23%), CTNNB1 (21%), FBFR2 (13%), FBXW7(10%) and RB1 (9%). PTEN mutations were found to associated with young age (< 60), early-stage, endometrioid histology, non-recurrence and better overall survival (OS). CTNNB1 mutations were associated with young age, endometrioid histology and better OS. On the other hands, TP53 mutations were associated with late-stage, non-endometrioid histology, high-grade, recurrence and worse OS. FBWX7 mutations were associated with late-stage, vascular invasion and lymph node metastasis. FGFR2 mutations correlated with deep (≥ 1/2) myometrial invasion.

Conclusion

Our comprehensive mutational profile will be useful for understanding and evaluating the molecular characteristics of EC tumors, and may lead to the establishment of novel treatment strategies that improve the survival of patients with EC in the future.

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.

Fibroblast growth factor receptor signaling as therapeutic targets in female reproductive system cancers

Ovarian cancer, cervical cancer and endometrial cancer are three relatively common malignant cancers of the female reproductive system. Despite improvements in female genital tract cancer detection and development of new therapeutic approaches, there are still poor prognoses and some do not respond to therapeutic patterns, displaying low survival and high frequency of recurrence. In an era of personalized medicine, novel therapeutic approaches with greater efficacy for these cancers represent an unmet need. One of the actionable signaling pathways is the fibroblast growth factor receptor (FGFR) signaling pathway. Several mutations and alterations in FGF/FGFR family members have been reported in human cancers. FGF/FGFR signaling pathway has become a new target for cancer therapy. This review will summarize the role of FGFR pathway and the genetic alterations of the FGF/FGFR related to female reproductive system cancer. We will describe the available inhibitors of FGFR pathway for potential treatment of female reproductive system cancer. Furthermore, we will discuss FGFR-targeted therapies under clinical development for treatment of female reproductive system cancer.

Discovery of Roblitinib (FGF401) as a Reversible-Covalent Inhibitor of the Kinase Activity of Fibroblast Growth Factor Receptor 4

FGF19 signaling through the FGFR4/β-klotho receptor complex has been shown to be a key driver of growth and survival in a subset of hepatocellular carcinomas, making selective FGFR4 inhibition an attractive treatment opportunity. A kinome-wide sequence alignment highlighted a poorly conserved cysteine residue within the FGFR4 ATP-binding site at position 552, two positions beyond the gate-keeper residue. Several strategies for targeting this cysteine to identify FGFR4 selective inhibitor starting points are summarized which made use of both rational and unbiased screening approaches. The optimization of a 2-formylquinoline amide hit series is described in which the aldehyde makes a hemithioacetal reversible-covalent interaction with cysteine 552. Key challenges addressed during the optimization are improving the FGFR4 potency, metabolic stability, and solubility leading ultimately to the highly selective first-in-class clinical candidate roblitinib.

FGFR aberrations increase the risk of brain metastases and predict poor prognosis in metastatic breast cancer patients

Background:

The survival status of patients with breast cancer and brain metastasis (BCBM) receiving current treatments is poor.

Method:

We designed a real-world study to investigate using patients’ clinical and genetic aberrations to forecast the prognoses of BCBM patients. We recruited 146 BCBM patients and analyzed their clinical features to evaluate the overall survival (OS). For genetic testing, 30 BCBM and 165 non-brain-metastatic (BM) metastatic breast cancer (MBC) patients from Hunan Cancer Hospital, and 86 BCBM and 1416 non-BM MBC patients from the Geneplus database who received circulating tumor DNA testing, were compared and analyzed.

Results:

Ki67 >14% and >3 metastatic brain tumors were significant risk factors associated with poor OS, while chemotherapy and brain radiotherapy were beneficial factors for better OS. Compared with non-BM MBC patients, BCBM patients had more fibroblast growth factor receptor (FGFR) aberrations. The combination of FGFR, TP53 and FLT1 aberrations plus immunohistochemistry HER2-positive were associated with an increased risk of brain metastasis (AUC = 77.13%). FGFR aberration alone was not only a predictive factor (AUC = 67.90%), but also a significant risk factor for poor progression-free survival (Logrank p = 0.029). FGFR1 aberration was more frequent than other FGFR family genes in BCBM patients, and FGFR1 aberration was significantly higher in BCBM patients than non-BM MBC patients. Most FGFR1-amplified MBC patients progressed within 3 months of the late-line (>2 lines) treatment.

Conclusion:

A group of genetic events, including FGFR, TP53 and FLT1 genetic aberrations, and HER2-positivity, forecasted the occurrence of BM in breast cancers. FGFR genetic aberration alone predicted poor prognosis.

The future of bladder cancer therapy: Optimizing the inhibition of the fibroblast growth factor receptor

Therapeutic options for metastatic bladder cancer (BC) have seen minimal evolution over the past 30 years, with platinum-based chemotherapy remaining the mainstay of standard of care for metastatic BC. Recently, five immune checkpoint inhibitors (ICIs) have been approved by the FDA as second-line therapy, and two ICIs are approved as first-line treatment in selected patients. Molecular alterations of muscle-invasive bladder cancer (MIBC) have been reported by The Cancer Genome Atlas. About 15% of patients with MIBC have molecular alterations in the fibroblast growth factor (FGF) axis. Several ongoing trials are testing novel FGF receptor (FGFR) inhibitors in patients with FGFR genomic aberrations. Recently, erdafitinib, a pan-FGFR inhibitor, was approved by the FDA in patients with metastatic BC who have progressed on platinum-based chemotherapy. We reviewed the literature over the last decade and provide a summary of current knowledge of FGF signaling, and the prognosis associated with FGFR mutations in BC. We cover the role of FGFR inhibition with non-selective and selective tyrosine kinase inhibitors as well as novel agents in metastatic BC. Efficacy and safety data including insights from mechanism-based toxicity are reported for selected populations of metastatic BC with FGFR aberrations. Current strategies to managing resistance to anti-FGFR agents is addressed, and the importance of developing reliable biomarkers as the therapeutic landscape moves towards an individualized therapeutic approach.

First-in-human phase I study of E7090, a novel selective fibroblast growth factor receptor inhibitor, in patients with advanced solid tumors

Fibroblast growth factor receptors (FGFR) are a family of transmembrane receptor tyrosine kinases involved in regulating cellular processes. FGFR mutations are implicated in oncogenesis, representing therapeutic potential in the form of FGFR inhibitors. This phase I, first‐in‐human study in Japan evaluated safety and tolerability of E7090, a potent selective FGFR1‐3 inhibitor, in patients with advanced solid tumors. Dose escalation (daily oral dose of 1‐180 mg) was carried out to assess dose‐limiting toxicity (DLT), maximum tolerated dose, and pharmacokinetics. Pharmacodynamic markers (serum phosphate, fibroblast growth factor 23, and 1,25‐(OH)₂‐vitamin D) were also evaluated. A total of 24 patients refractory to standard therapy or for whom no appropriate treatment was available were enrolled. No DLT were observed up to the 140‐mg dose; one patient in the 180‐mg cohort experienced a DLT (increased aspartate aminotransferase/alanine aminotransferase, grade 3). The maximum tolerated dose was not reached. Dose‐dependent increases in the maximum concentration and area under the curve from time 0 to the last measurable concentration were observed up to 180 mg. Dose‐dependent increases were observed in all pharmacodynamic markers and plateaued at 100‐140 mg, indicating sufficient FGFR pathway inhibition at doses ≥100 mg. In conclusion, E7090 showed a manageable safety profile with no DLT at doses ≤140 mg. Maximum tolerated dose was not determined. The recommended dose for the follow‐up expansion part, restricted to patients with tumors harboring FGFR alterations, was determined as 140 mg, once daily.

Nicotinamide-Ponatinib Analogues as Potent Anti-CML and Anti-AML Compounds

Ponatinib is a multikinase inhibitor that is used to treat chronic myeloid leukemia patients harboring mutated ABL1(T315I) kinase. Due to the potent inhibition of FLT3, RET, and fibroblast growth factor receptors (FGFRs), it is also being evaluated against acute myeloid leukemia (AML), biliary, and lung cancers. The multikinase inhibition profile of ponatinib may also account for its toxicity, thus analogs with improved kinase selectivity or different kinase inhibition profiles could be better tolerated. The introduction of nitrogen into drug compounds can enhance efficacy and drug properties (a concept called "necessary nitrogen"). Here, we introduce additional nitrogen into the benzamide moiety of ponatinib to arrive at nicotinamide analogs. A nicotinamide analogue of ponatinib, HSN748, retains activity against FLT3, ABL1, RET, and PDGFRα/β but loses activity against c-Src and P38α. MNK1 and 2 are key kinases that phosphorylate eIF4E to regulate the protein translation complex. MNK also modulates mTORC1 signaling and contributes to rapamycin resistance. Inhibitors of MNK1 and 2 are being evaluated for anticancer therapy. Ponatinib is not a potent inhibitor of MNK1 or 2, but the nicotinamide analogs are potent inhibitors of MNKs. This illustrates a powerful demonstration of the necessary nitrogen concept to alter both the potency and selectivity of drugs.

Receptor Tyrosine Kinases as Therapeutic Targets for Alcohol Use Disorder

The receptor tyrosine kinases (RTKs) are a large family of proteins that transduce extracellular signals to the inside of the cell to ultimately affect important cellular functions such as cell proliferation, survival, apoptosis, differentiation, and migration. They are expressed in the nervous system and can regulate behavior through modulation of neuronal and glial function. As a result, RTKs are implicated in neurodegenerative and psychiatric disorders such as depression and addiction. Evidence has emerged that 5 RTKs (tropomyosin-related kinase B (TrkB), RET proto-oncogene (RET), anaplastic lymphoma kinase (ALK), fibroblast growth factor receptor (FGFR), and epidermal growth factor receptor (EGFR)) modulate alcohol drinking and other behaviors related to alcohol addiction. RTKs are considered highly "druggable" targets and small-molecule inhibitors of RTKs have been developed for the treatment of various conditions, particularly cancer. These kinases are therefore attractive targets for the development of new pharmacotherapies to treat alcohol use disorder (AUD). This review will examine the preclinical evidence describing TrkB, RET, ALK, FGFR, and EGFR modulation of alcohol drinking and other behaviors relevant to alcohol abuse.

Fibroblast growth factor receptor inhibitors: patent review (2015-2019)

Introduction: fibroblast growth factor receptors (FGFRs) are a family of tyrosine-kinase receptors whose signaling cascade regulates cellular proliferation, differentiation, and survival. Deregulation of the FGFR pathway is recognized as a driving factor in tumor development. On this basis, FGFR is an attractive target for anti-cancer small-molecule therapeutic agents.Areas covered: This review summarizes patent and literature publications spanning from 2015 to 2019 pertaining to small-molecule FGFR kinase inhibitors.Expert opinion: The first generation of non-covalent FGFR inhibitors is characterized by a broad spectrum of activity and a relatively high toxicity profile. The second generation of FGFR inhibitors shows higher selectivity and a more favorable toxicity profile, but the clinical use appears restricted only to small subsets of cancers strongly dependent on FGFR signaling. Nevertheless, erdafitinib has been approved for the treatment of metastatic urothelial carcinoma, becoming the first marketed selective FGFR inhibitor. The insurgence of mutant kinases, resistant to available therapies, has led to the development of irreversible FGFR inhibitors. The adoption of safer and more selective covalent inhibitors might supersede reversible inhibitors in specific therapeutic areas. Alternative strategies, such as FGF trapping by protein or small-molecule therapeutics, deserve attention and further investigations to unravel their potential.

Identification of a novel oncogenic mutation of FGFR4 in gastric cancer

Gastric cancer remains one of the leading causes of cancer death worldwide. Despite intensive investigations of treatments over the past three decades, the poor prognosis of patients with unresectable advanced or recurrent gastric cancer has not significantly changed, and improved therapies are required. Here, we report the identification of an oncogenic mutation in FGFR4 in a human gastric tumour that leads to constitutive activation of its product, FGFR4. The G636C-FGFR4 tyrosine kinase domain mutation was found in 1 of 83 primary human gastric tumours. The G636C mutation increased FGFR4 autophosphorylation, and activated FGFR4 downstream signalling molecules and enhanced anchorage-independent cell growth when expressed in NIH/3T3 cells. 3D-structural analysis and modelling of FGFR4 suggest that G636C destabilizes an auto-inhibitory conformation and stabilizes an active conformation, leading to increased kinase activation. Ba/F3 cell lines expressing the G636C-FGFR4 mutant were significantly more sensitive to ASP5878, a selective FGFR inhibitor, than the control. Oral administration of ASP5878 significantly inhibited the growth of tumours in mice engrafted with G636C-FGFR4/3T3 cells. Together, our results demonstrate that mutationally activated FGFR4 acts as an oncoprotein. These findings support the therapeutic targeting of FGFR4 in gastric cancer.

An open-label phase IB study to evaluate GSK3052230 in combination with paclitaxel and carboplatin, or docetaxel, in FGFR1-amplified non-small cell lung cancer

OBJECTIVES

GSK3052230 (FP-1039) is a soluble fusion protein that acts as ligand trap sequestering fibroblast growth factors (FGFs) involved in tumor growth and angiogenesis, while sparing the hormonal FGFs. Because of this selectivity, the molecule is predicted to avoid toxicities associated with small molecule inhibitors of FGFR, including hyperphosphatemia and retinal, nail, and skin toxicities. Herein we report the results of a phase 1b study where GSK3052330 was administered with standard of care chemotherapy in FGFR1-amplified squamous non-small cell lung cancer (sqNSCLC) patients.

METHODS AND METHODS

Eligible patients with stage IV or recurrent metastatic sqNSCLC harboring FGFR1 gene amplification received escalating doses of GSK3052230 in combination with paclitaxel and carboplatin at the starting doses 200 mg/m² and AUC of 6, respectively, in the first line setting (Arm A) or docetaxel 75 mg/m² in second line (Arm B). The primary endpoints of the study were safety and tolerability, to identify a maximum tolerated dose (MTD), and to assess overall response rate (ORR) based on investigator assessment.

RESULTS

Twenty-nine patients were enrolled into the study, including 20 patients on Arm A and 9 patients on Arm B. There were no dose limiting toxicities in either Arm and the MTD was not reached. The most common adverse events (AEs) were compatible with the chemotherapy backbone used in each Arm, including neutropenia, alopecia, nausea, arthralgia, asthenia, diarrhea and peripheral neuropathy. The overall response rate and median progression-free survival were 47% and 5.5 months, respectively, for Arm A and 0% and 4.6 months, respectively, for Arm B.

CONCLUSION

GSK3052230 is a novel FGFR pathway inhibitor, which is well tolerated in combination with chemotherapy. Importantly, AEs associated with small molecule inhibitors of FGFR were not observed, as predicted by the unique mechanism of action of this drug.

Fibroblast Growth Factor Receptors (FGFRs): Structures and Small Molecule Inhibitors

Fibroblast growth factor receptors (FGFRs) are a family of receptor tyrosine kinases expressed on the cell membrane that play crucial roles in both developmental and adult cells. Dysregulation of FGFRs has been implicated in a wide variety of cancers, such as urothelial carcinoma, hepatocellular carcinoma, ovarian cancer and lung adenocarcinoma. Due to their functional importance, FGFRs have been considered as promising drug targets for the therapy of various cancers. Multiple small molecule inhibitors targeting this family of kinases have been developed, and some of them are in clinical trials. Furthermore, the pan-FGFR inhibitor erdafitinib (JNJ-42756493) has recently been approved by the U.S. Food and Drug Administration (FDA) for the treatment of metastatic or unresectable urothelial carcinoma (mUC). This review summarizes the structure of FGFR, especially its kinase domain, and the development of small molecule FGFR inhibitors.

Discovery of a series of dimethoxybenzene FGFR inhibitors with 5H-pyrrolo[2,3-b]pyrazine scaffold: structure-activity relationship, crystal structural characterization and in vivo study

Genomic alterations are commonly found in the signaling pathways of fibroblast growth factor receptors (FGFRs). Although there is no selective FGFR inhibitors in market, several promising inhibitors have been investigated in clinical trials, and showed encouraging efficacies in patients. By designing a hybrid between the FGFR-selectivity-enhancing motif dimethoxybenzene group and our previously identified novel scaffold, we discovered a new series of potent FGFR inhibitors, with the best one showing sub-nanomolar enzymatic activity. After several round of optimization and with the solved crystal structure, detailed structure—activity relationship was elaborated. Together with in vitro metabolic stability tests and in vivo pharmacokinetic profiling, a representative compound (35) was selected and tested in xenograft mouse model, and the result demonstrated that inhibitor 35 was effective against tumors with FGFR genetic alterations, exhibiting potential for further development.

A Phase I, Open-Label, Multicenter, Dose-escalation Study of the Oral Selective FGFR Inhibitor Debio 1347 in Patients with Advanced Solid Tumors Harboring FGFR Gene Alterations

PURPOSE

To investigate tolerability, efficacy, and pharmacokinetics/pharmacodynamics of Debio 1347, a selective FGFR inhibitor.

PATIENTS AND METHODS

This was a first-in-human, multicenter, open-label study in patients with advanced solid tumors harboring FGFR1-3 gene alterations. Eligible patients received oral Debio 1347 at escalating doses once daily until disease progression or intolerable toxicity. Dose-limiting toxicities (DLT) were evaluated during the first 4 weeks on treatment, pharmacokinetics/pharmacodynamics postfirst dose and after 4 weeks.

RESULTS

A total of 71 patients were screened and 58 treated with Debio 1347 at doses from 10 to 150 mg/day. Predominant tumor types were breast and biliary duct cancer, most common gene alterations were FGFR1 amplifications (40%) and mutations in FGFR2 (12%) and FGFR3 (17%); 12 patients (21%) showed FGFR fusions. Five patients at three dose levels had six DLTs (dry mouth/eyes, hyperamylasemia, hypercalcemia, hyperbilirubinemia, hyperphosphatemia, and stomatitis). The maximum tolerated dose was not reached, but dermatologic toxicity became sometimes dose limiting beyond the DLT period at ≥80 mg/day. Adverse events required dose modifications in 52% of patients, mostly due to dose-dependent, asymptomatic hyperphosphatemia (22%). RECIST responses were seen across tumor types and mechanisms of FGFR activation. Six patients, 3 with FGFR fusions, demonstrated partial responses, 10 additional patients' tumor size regressions of ≤30%. Plasma half-life was 11.5 hours. Serum phosphate increased with Debio 1347 plasma levels and confirmed target engagement at doses ≥60 mg/day.

CONCLUSIONS

Preliminary efficacy was encouraging and tolerability acceptable up to 80 mg/day, which is now used in an extension part of the study.

Repurposing suramin for the treatment of breast cancer lung metastasis with glycol chitosan-based nanoparticles

Suramin (SM), a drug for African sleeping sickness and river blindness therapy, has been investigated in various clinical trials for cancer therapy. However, SM was eventually withdrawn from the market because of its narrow therapeutic window and the side effects associated with multiple targets. In this work, we developed a simple but effective system based on a nontoxic dose of SM combined with a chemotherapeutic agent for the treatment of metastatic triple-negative breast cancer (TNBC). SM and glycol chitosan (GCS) formed nanogels because of the electrostatic effect, whereas doxorubicin (DOX) was incorporated into the system through the hydrophilic and hydrophobic interactions between DOX and GCS as well as the ionic interactions between DOX and SM to yield GCS-SM/DOX nanoparticles (NPs). GCS-SM/DOX NPs have a size of approximately 186 nm and a spherical morphology. In vitro experiments showed that GCS-SM NPs could effectively inhibit cancer cell migration and invasion, as well as angiogenesis. Furthermore, in a TNBC lung metastasis animal model, GCS-SM/DOX NPs significantly reduced tumor burden and extended the lifespan of animals, while not inducing cardio and renal toxicities associated with the DOX and SM, respectively. As all the components used in this system are biocompatible and easy for large-scale fabrication, the GCS-SM/DOX system is highly translatable for the metastatic breast cancer treatment. STATEMENT OF SIGNIFICANCE: The doxorubicin-loaded glycol chitosan-suramin nanoparticle (GCS-SM/DOX) is novel in the following aspects: SM acts as not only a gelator for the first time in the preparation of the nanoparticle but also an active pharmaceutical agent in the dosage form. GCS-SM/DOX NP significantly reduced tumor burden and extended the lifespan of animals with triple-negative breast cancer lung metastasis. GCS-SM/DOX NPs attenuate cardio and renal toxicities associated with the DOX and SM. The GCS-SM/DOX system is highly translatable because of its simple, one-pot, and easy-to-scale-up preparation protocol.

Cholangiocarcinoma With FGFR Genetic Aberrations: A Unique Clinical Phenotype

Purpose

FGFR genetic aberrations (GAs) occur in an estimated 10% to 16% of intrahepatic cholangiocarcinomas (CCAs). The natural history of CCA with FGFR GAs, the prognostic role of coexisting GAs, and the outcome with FGFR-targeted inhibitors are unknown.

Patients and Methods

Patients with CCA with FGFR GAs were identified using next-generation sequencing or fluorescence in situ hybridization from four tertiary cancer centers and compared with FGFR wild-type counterparts. Data reviewed included demographic, treatment, overall survival (OS), and GA data. Fisher’s exact test, Kaplan-Meier plots, and log-rank tests were used for statistical analysis.

Results

Three hundred seventy-seven patients with CCA were identified, and 95 had FGFR GAs. FGFR2 GA was most common (n = 74, with 63 fusions) and seen in intrahepatic CCA. In patients with CCA, FGFR GAs occurred more frequently in younger patients (≤ 40 years; 20%) compared with older patients (> 40 years; 6.7%; P < .001), presented at an earlier stage (TNM stage I/II v III/IV: 35.8% v 22%, respectively; P = .001), and were associated with a longer OS compared with patients without FGFR GAs (37 v 20 months, respectively; P < .001). This difference remained significant after excluding 36 patients treated with FGFR inhibitors. There was no OS difference ( P = .60) between CCA with FGFR2 fusions (n = 63) versus other FGFR GAs (n = 29). Patients with FGFR GAs had a better OS with FGFR-targeted therapy compared with standard treatment ( P = .01). BAP1 mutation was the most common coexisting mutation without prognostic impact, whereas TP53 ( P = .04) and CDKN2A/B ( P = .04) were correlated with a shorter OS.

Conclusion

CCA with FGFR GAs represents a unique subtype occurring in younger patients with an indolent disease course. FGFR-targeted therapy may have a positive impact on OS in this subgroup.

FGF9/FGFR2 increase cell proliferation by activating ERK1/2, Rb/E2F1, and cell cycle pathways in mouse Leydig tumor cells

Fibroblast growth factor 9 (FGF9) promotes cancer progression; however, its role in cell proliferation related to tumorigenesis remains elusive. We investigated how FGF9 affected MA‐10 mouse Leydig tumor cell proliferation and found that FGF9 significantly induced cell proliferation by activating ERK1/2 and retinoblastoma (Rb) phosphorylations within 15 minutes. Subsequently, the expressions of E2F1 and the cell cycle regulators: cyclin D1, cyclin E1 and cyclin‐dependent kinase 4 (CDK4) in G₁ phase and cyclin A1, CDK2 and CDK1 in S‐G₂/M phases were increased at 12 hours after FGF9 treatment; and cyclin B1 in G₂/M phases were induced at 24 hours after FGF9 stimulation, whereas the phosphorylations of p53, p21 and p27 were not affected by FGF9. Moreover, FGF9‐induced effects were inhibited by MEK inhibitor PD98059, indicating FGF9 activated the Rb/E2F pathway to accelerate MA‐10 cell proliferation by activating ERK1/2. Immunoprecipitation assay and ChIP‐quantitative PCR results showed that FGF9‐induced Rb phosphorylation led to the dissociation of Rb‐E2F1 complexes and thereby enhanced the transactivations of E2F1 target genes, Cyclin D1, Cyclin E1 and Cyclin A1. Silencing of FGF receptor 2 (FGFR2) using lentiviral shRNA inhibited FGF9‐induced ERK1/2 phosphorylation and cell proliferation, indicating that FGFR2 is the obligate receptor for FGF9 to bind and activate the signaling pathway in MA‐10 cells. Furthermore, in a severe combined immunodeficiency mouse xenograft model, FGF9 significantly promoted MA‐10 tumor growth, a consequence of increased cell proliferation and decreased apoptosis. Conclusively, FGF9 interacts with FGFR2 to activate ERK1/2, Rb/E2F1 and cell cycle pathways to induce MA‐10 cell proliferation in vitro and tumor growth in vivo.

Targeted Theranostic Nanoparticles for Brain Tumor Treatment

The poor prognosis and rapid recurrence of glioblastoma (GB) are associated to its fast-growing process and invasive nature, which make difficult the complete removal of the cancer infiltrated tissues. Additionally, GB heterogeneity within and between patients demands a patient-focused method of treatment. Thus, the implementation of nanotechnology is an attractive approach considering all anatomic issues of GB, since it will potentially improve brain drug distribution, due to the interaction between the blood⁻brain barrier and nanoparticles (NPs). In recent years, theranostic techniques have also been proposed and regarded as promising. NPs are advantageous for this application, due to their respective size, easy surface modification and versatility to integrate multiple functional components in one system. The design of nanoparticles focused on therapeutic and diagnostic applications has increased exponentially for the treatment of cancer. This dual approach helps to understand the location of the tumor tissue, the biodistribution of nanoparticles, the progress and efficacy of the treatment, and is highly useful for personalized medicine-based therapeutic interventions. To improve theranostic approaches, different active strategies can be used to modulate the surface of the nanotheranostic particle, including surface markers, proteins, drugs or genes, and take advantage of the characteristics of the microenvironment using stimuli responsive triggers. This review focuses on the different strategies to improve the GB treatment, describing some cell surface markers and their ligands, and reports some strategies, and their efficacy, used in the current research.

Structural Alterations in Human Fibroblast Growth Factor Receptors in Carcinogenesis

Fibroblast growth factor (FGF) plays an important role in human embryogenesis, angiogenesis, cell proliferation, and differentiation. Carcinogenesis is accompanied by aberrant constitutive activation of FGF receptors (FGFRs) resulting from missense mutation in the FGFR1-4 genes, generation of chimeric oncogenes, FGFR1-4 gene amplification, alternative splicing shift toward formation of mesenchymal FGFR isoforms, and FGFR overexpression. Altogether, these alterations contribute to auto- and paracrine stimulation of cancer cells and neoangiogenesis. Certain missense mutations are found at a high rate in urinary bladder cancer and can be used for non-invasive cancer recurrence diagnostics by analyzing urine cell pellet DNA. Chimeric FGFR1/3 and amplified FGFR1/2 genes can predict cell response to the targeted therapy in various oncological diseases. In recent years, high-throughput sequencing has been used to analyze exomes of virtually all human tumors, which allowed to construct phylogenetic trees of clonal cancer evolution with special emphasis on driver mutations in FGFR1-4 genes. At present, FGFR blockers, such as multi-kinase inhibitors, specific FGFR inhibitors, and FGF ligand traps are being tested in clinical trials. In this review, we discuss current data on the functioning of the FGFR family proteins in both normal and cancer cells, mutations in the FGFR1-4 genes, and mechanisms underlying their oncogenic potential, which might be interesting to a broad range of scientists searching for specific tumor markers and targeted anti-cancer drugs.

Current Status of Fibroblast Growth Factor Receptor-Targeted Therapies in Breast Cancer

Breast cancer (BC) is the most common malignancy and second only to lung cancer in terms of mortality in women. Despite the incredible progress made in this field, metastatic breast cancer has a poor prognosis. In an era of personalized medicine, there is an urgent need for better knowledge of the biology leading to the disease, which can lead to the design of increasingly accurate drugs against patients' specific molecular aberrations. Among one of the actionable targets is the fibroblast growth factor receptor (FGFR) pathway, triggered by specific ligands. The Fibroblast Growth Factor Receptors/Fibroblast Growth Factors (FGFRs/FGFs) axis offers interesting molecular targets to be pursued in clinical development. This mini-review will focus on the current knowledge of FGFR mutations, which lead to tumor formation and summarizes the state-of-the-art therapeutic strategies for targeted treatments against the FGFRs/FGFs axis in the context of BC.

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.

FGF Family: From Drug Development to Clinical Application

Fibroblast growth factor (FGF) belongs to a large family of growth factors. FGFs use paracrine or endocrine signaling to mediate a myriad of biological and pathophysiological process, including angiogenesis, wound healing, embryonic development, and metabolism regulation. FGF drugs for the treatment of burn and ulcer wounds are now available. The recent discovery of the crucial roles of the endocrine-acting FGF19 subfamily in maintaining homeostasis of bile acid, glucose, and phosphate further extended the activity profile of this family. Here, the applications of recombinant FGFs for the treatment of wounds, diabetes, hypophosphatemia, the development of FGF receptor inhibitors as anti-neoplastic drugs, and the achievements of basic research and applications of FGFs in China are reviewed.

Endometrial cancer: Molecular markers and management of advanced stage disease

Endometrial cancer is the most prevalent gynecologic cancer in the United States. Over the last 10 years, death rates from endometrial cancer have been rising about 1.4% per year. Traditionally endometrial cancer treatment has been driven by stage and histology. Recent studies have, however, shown that cancers of the same stage and histology have very distinct molecular and genomic profiles. Translational research is progressing rapidly and endometrial cancer-specific precision medicine is evolving. The first tissue agnostic therapy based on the molecular profile of the tumor was approved by the FDA this year. The approval of immune checkpoint inhibitor, pembrolizumab (anti-PD-1), for all solid tumors with defective DNA mismatch repair, could benefit 20-30% of patients with advanced endometrial cancer. Other genomic changes and molecular markers in endometrial cancer, such as hormone receptor status, could lead to more tailored therapy in the future. Pre-clinical and clinical investigations of targeted therapies suggest efficacy for some agents. Single agent targeted therapies, however, have modest activity. Identifying biomarkers that effectively determine response to targeted therapy remains a challenge. The next generation of clinical trials will focus on novel combinations and how to best utilize the advances that have been made in sequencing technology and bioinformatics. Although there is currently an immense body of data and many options for obtaining genomic characteristics of endometrial cancer, how to interpret and utilize this data is still being explored. This review will summarize the important trials that have led to the treatment options we have for advanced and/or recurrent endometrial cancer and discuss the important studies that have led to a better understanding of the distinctive molecular and genomic profiles within endometrial cancer. We will review the current status of biomarker-driven targeted therapy in endometrial cancer and the rationale behind ongoing clinical trials that are utilizing novel targeted agents.

miR‑494 inhibits cancer‑initiating cell phenotypes and reverses resistance to lapatinib by downregulating FGFR2 in HER2‑positive gastric cancer

In gastric cancer, >15% of cases are associated with the amplification of human epidermal growth factor receptor 2 (HER2), which leads to poor clinical outcomes. Lapatinib, a potent ATP‑competitive inhibitor, is a small, orally active molecule, which inhibits the tyrosine kinases of HER2 and epidermal growth factor receptor type 1. The activation of receptor tyrosine kinases can contribute to lapatinib resistance in HER2‑positive gastric cancer. The aim of the present study was to explore the effects of miR‑494 and FGFR2 in regulation of cancer‑initiating cell phenotypes and therapeutic efficiency of lapatinib in HER2‑positive gastric cancer. Western blot analysis was used to identify that the expression of fibroblast growth factor receptor 2 (FGFR2), a receptor tyrosine kinase, was upregulated in gastric cancer tissues. Formation of cancer initiating cells (CICs) and resistance to lapatinib were determined using sphere growth assay and MTT assay, respectively. The overexpression of FGFR2 promoted the generation of cancer‑initiating cells (CICs) and resistance to lapatinib in HER2‑positive gastric cancer YCC1 cells. In addition, it was observed that overexpression of microRNA (miR)‑494 downregulated the protein expression of FGFR2, inhibited the formation of CICs and reversed lapatinib resistance in YCC1‑F cells (HER2‑positive, FGFR2 overexpressing and lapatinib‑resistant gastric cancer cells). Therefore, it was concluded that miR‑494 inhibited the CIC phenotype and reversed resistance to lapatinib by inhibiting FGFR2 in HER2‑positive gastric cancer.

Humanization of fibroblast growth factor 1 single-chain antibody and validation for its antitumorigenic efficacy in breast cancer and glioma cells

Single‐chain variable fragment (scFv) antibodies are the smallest immunoglobulins with high antigen‐binding affinity. We have previously reported that fibroblast growth factor 1 played pivotal roles in cancer development and generated a mouse scFv (mscFv1C9) could effectively prohibit cancer cell proliferation in vitro and in vivo. Here, we further humanized this scFv (hscFv1C9) using a structure‐guided complementarity determining region grafting strategy. The purified hscFv1C9 maintained similar antigen‐binding affinity and specificity as mscFv1C9, and it was capable of inhibiting growth of different tumours in vitro and in vivo. These data strongly suggested that hscFv1C9 has antitumour potentials.

2-Formylpyridyl Ureas as Highly Selective Reversible-Covalent Inhibitors of Fibroblast Growth Factor Receptor 4

As part of a project to identify FGFR4 selective inhibitors, scaffold morphing of a 2-formylquinoline amide hit identified series of 2-formylpyridine ureas (2-FPUs) with improved potency and physicochemical properties. In particular, tetrahydronaphthyridine urea analogues with cellular activities below 30 nM have been identified. Consistent with the hypothesized reversible-covalent mechanism of inhibition, the 2-FPUs exhibited slow binding kinetics, and the aldehyde, as the putative electrophile, could be demonstrated to be a key structural element for activity.

Discovery of NKCC1 as a potential therapeutic target to inhibit hepatocellular carcinoma cell growth and metastasis

Metastasis is the essential cause for the high mortality of hepatocellular carcinoma (HCC). In order to investigate the mechanism of metastasis, and to discover therapeutic targets for HCC, the quantitative proteomic technique was applied to characterize the plasma membrane proteins of two HCC cell lines with low (MHCC97L) or high (MHCC97H) metastatic potentials. One of the plasma membrane proteins, sodium-potassium-chloride cotransporter 1 (NKCC1), was upregulated in MHCC97H cell line. Immunohistochemistry result in HCC patients showed that NKCC1 expression was associated with poor differentiation and microvascular invasion. Knockdown of NKCC1 via RNA interference reduced HCC cell proliferation and invasion abilities in vitro and in vivo, whereas over-expression of NKCC1 significantly increased HCC cell proliferation and invasion abilities in vitro and in vivo. Additionally, blocking NKCC1 activity with bumetanide attenuated the proliferation and invasion abilities of HCC cells in vitro and limited the HCC growth in vivo. Further results suggested that NKCC1 promotes the invasion ability via MMP-2 activity, and that the WNK1/OSR1/NKCC1 signal pathway might play roles in HCC metastasis. For the first time, our study demonstrated that NKCC1 plays a role in HCC metastasis, and could be served as a potential target to inhibit HCC cell growth and metastasis.

Genomic Profiling of Biliary Tract Cancers and Implications for Clinical Practice

OPINION STATEMENT

Biliary tract cancers are relatively uncommon, have an aggressive disease course and a dismal clinical outcome. Until recently, there have been very few clinical advances in the management of these patients and gemcitabine-based chemotherapy has been the only widely accepted systemic therapy. The advent of next generation sequencing technologies can potentially change the treatment paradigm of this disease. Targeted therapy directed against actionable mutations and identification of molecular subsets with distinct prognostic significance is now feasible in clinical practice. Mutation profiling has highlighted the genomic differences between the intra, extrahepatic cholangiocarcinoma, and gallbladder cancer. The mutational spectrum of intrahepatic cholangiocarcinoma differs according to geographic location and ethnicity. There is a higher incidence of chromatin modulating gene mutations in Western patients as compared with Asian patients with liver fluke-associated cholangiocarcinoma. KRAS and p53 mutations are associated with an aggressive disease prognosis while FGFR mutations may signify a relatively indolent disease course of intrahepatic cholangiocarcinoma. FGFR and IDH mutations have promising agents in clinical trials at this time. An estimated 15 % of gallbladder cancers have Her2/neu amplification and can be targeted by trastuzumab. On the other hand, an estimated 10-15 % of cholangiocarcinomas have DNA repair mutations and may be candidates for immune therapies with checkpoint inhibitors. The promise of targeted therapies for biliary tract cancers can be fulfilled with well-designed, prospective, and multi-center clinical trials.