The FGFR1 V561M Gatekeeper Mutation Drives AZD4547 Resistance through STAT3 Activation and EMT

Targeting fibroblast growth factor receptor (FGFR) with inhibitors in head and neck cancers: Their roles, mechanisms and challenges

Head and neck squamous cell carcinoma (HNSCC) is a common and aggressive type of cancer with significant rates of morbidity and mortality. Traditional treatment options, including radiotherapy, chemotherapy, and surgery, are widely used, but their effectiveness can be uncertain. As research in cancer therapies evolves, molecular-targeted therapies are increasingly recognized as promising alternatives for managing malignant tumors. Fibroblast growth factor receptors (FGFRs) have been shown to be one of the essential components in the pathways in the progression of HNSCC. This review aims to summarize and discuss the structure, functions, signaling pathways, abnormal alterations of FGFRs, and their roles in tumorigenesis and development. We have accumulated information from in vitro, in vivo, and clinical studies regarding FGFR inhibitors in HNSCC. However, the efficacy of FGFR inhibitors as a cancer therapy is limited, which may be due to the resistance to FGFR inhibitors. In this review we also discuss the potential mechanisms of FGFR inhibitor resistance in HNSCC. By enriching our understanding of the treatment with and resistance of FGFR inhibitors in HNSCC, researchers may unveil new therapeutic targets or strategies to enhance the efficacy of FGFR inhibitors in this context.

Clinical advances and challenges in targeting FGF/FGFR signaling in lung cancer

Fibroblast growth factors (FGFs) and their receptors regulate numerous cellular processes, such as metabolism and signal transduction, but can also drive tumorigenesis. Specifically, in lung cancer, the overexpression of FGFs, as well as the amplification, mutation and fusion of FGFR genes, are closely linked to the initiation, progression and resistance of the disease, suggesting that targeting FGF/FGFR is an attractive therapeutic strategy for lung cancer treatment. Nintedanib, a multitarget tyrosine kinase inhibitor (TKI) used in combination with docetaxel, has shown some success as a second-line therapy for lung cancer. However, clinical trials evaluating other FGFR inhibitors have yielded mixed results, indicating substantial complexity in targeting aberrant FGF/FGFR signaling. In this review, we describe the aberrations in FGF/FGFR signaling in lung cancer and summarize the clinical efficacy of FGFR inhibitors, such as multitarget TKIs, selective FGFR-TKIs and biological agents. We also discuss various challenges associated with FGFR targeting in lung cancer, including precision patient selection, toxicity and resistance. Finally, we provide perspectives on future directions, namely, developing novel FGFR-targeting drugs, such as FGFR degraders and more specific FGFR-TKIs, adopting combination therapy and targeting FGFs.

Biomarkers of treatment response in bladder cancer

INTRODUCTION

There have been many recent advancements in the treatment of bladder cancer including the approval of novel intravesical agents for non-muscle-invasive disease and systemic-targeted therapeutics for muscle-invasive and advanced disease. However, treatment strategies for bladder cancer are still largely based on clinicopathologic characteristics.

AREAS COVERED

Based on primary literature sourced from PubMed, Embase, and Cochrane Library, we review the current status of molecular markers and biomarker panels with respective to their value in predicting response to standard chemotherapeutics and novel agents in non-muscle-invasive, muscle-invasive, and advanced bladder cancer.

EXPERT OPINION

Several biomarkers based on molecular characterization of tumors and quantification of circulating tumor DNA have been associated with response or resistance to standard chemotherapeutics. More recent investigations have reported on predictive biomarkers for novel therapeutics in bladder cancer, although large-scale validation is still needed. Given the increasing therapeutic options for this disease, employment of such predictive biomarkers may help guide treatment selection and sequencing.

Induction, growth, drug resistance, and metastasis: A comprehensive summary of the relationship between STAT3 and gastric cancer

Gastric cancer is a prevalent and highly lethal malignancy that poses substantial challenges to healthcare systems globally. Owing to its often asymptomatic nature in early stages, diagnosis frequently occurs at advanced stages when surgical intervention is no longer a viable option, forcing most patients to rely on nonsurgical treatments such as chemotherapy, targeted therapies, and emerging immunotherapies. Unfortunately, the therapeutic response rates for these treatments are suboptimal, and even among responders, the eventual development of drug resistance remains a significant clinical hurdle. Signal transducer and activator of transcription 3 (STAT3) is a widely expressed cellular protein that plays crucial roles in regulating cellular processes such as growth, metabolism, and immune function. Aberrant activation of the STAT3 pathway has been implicated in the initiation, progression, and therapeutic resistance of several cancers, with gastric cancer being particularly affected. Dysregulated STAT3 signaling not only drives tumorigenesis but also facilitates the development of resistance to chemotherapy and targeted therapies, as well as promotes metastatic dissemination. In this study, we explored the critical role of the STAT3 signaling cascade in the pathogenesis of gastric cancer, its contribution to drug resistance, and its involvement in the metastatic process. Furthermore, we assess recent advances in the development of STAT3 inhibitors and their potential application as therapeutic agents in the treatment of gastric cancer. This work provides a comprehensive overview of the current understanding of STAT3 in gastric cancer and offers a foundation for future research aimed at improving therapeutic outcomes in this challenging disease.

Discovery and characterization of novel FGFR1 inhibitors in triple-negative breast cancer via hybrid virtual screening and molecular dynamics simulations

The overexpression of FGFR1 is thought to significantly contribute to the progression of triple-negative breast cancer (TNBC), impacting aspects such as tumorigenesis, growth, metastasis, and drug resistance. Consequently, the pursuit of effective inhibitors for FGFR1 is a key area of research interest. In response to this need, our study developed a hybrid virtual screening method. Utilizing KarmaDock, an innovative algorithm that blends deep learning with molecular docking, alongside Schrödinger's Residue Scanning. This strategy led us to identify compound 6, which demonstrated promising FGFR1 inhibitory activity, evidenced by an IC50 value of approximately 0.24 nM in the HTRF bioassay. Further evaluation revealed that this compound also inhibits the FGFR1 V561M variant with an IC50 value around 1.24 nM. Our subsequent investigations demonstrate that Compound 6 robustly suppresses the migration and invasion capacities of TNBC cell lines, through the downregulation of p-FGFR1 and modulation of EMT markers, highlighting its promise as a potent anti-metastatic therapeutic agent. Additionally, our use of molecular dynamics simulations provided a deeper understanding of the compound's specific binding interactions with FGFR1.

Computational biophysical characterization of the effect of gatekeeper mutations on the binding of ponatinib to the FGFR kinase

Fibroblast Growth Factor Receptor (FGFR) is connected to numerous downstream signalling cascades regulating cellular behavior. Any dysregulation leads to a plethora of illnesses, including cancer. Therapeutics are available, but drug resistance driven by gatekeeper mutation impedes the treatment. Ponatinib is an FDA-approved drug against BCR-ABL kinase and has shown effective results against FGFR-mediated carcinogenesis. Herein, we undertake molecular dynamics simulation-based analysis on ponatinib against all the FGFR isoforms having Val to Met gatekeeper mutations. The results suggest that ponatinib is a potent and selective inhibitor for FGFR1, FGFR2, and FGFR4 gatekeeper mutations. The extensive electrostatic and van der Waals interaction network accounts for its high potency. The FGFR3_VM mutation has shown resistance towards ponatinib, which is supported by their lesser binding affinity than wild-type complexes. The disengaged molecular brake and engaged hydrophobic spine were believed to be the driving factors for weak protein-ligand interaction. Taken together, the inhibitory and structural characteristics exhibited by ponatinib may aid in thwarting resistance based on Val-to-Met gatekeeper mutations at an earlier stage of treatment and advance the design and development of other inhibitors targeted at FGFRs harboring gatekeeper mutations.

The anti-tumor effects of AZD4547 on ovarian cancer cells: differential responses based on c-Met and FGF19/FGFR4 expression

BACKGROUND

The FGF/FGFR signaling pathway plays a critical role in human cancers. We analyzed the anti-tumor effect of AZD4547, an inhibitor targeting the FGF/FGFR pathway, in epithelial ovarian cancer (EOC) and strategies on overcoming AZD4547 resistance.

METHODS

The effect of AZD4547 on cell viability/migration was evaluated and in vivo experiments in intraperitoneal xenografts using EOC cells and a patient-derived xenograft (PDX) model were performed. The effect of the combination of AZD4547 with SU11274, a c-Met-specific inhibitor, FGF19-specific siRNA, or an FGFR4 inhibitor was evaluated by MTT assay.

RESULTS

AZD4547 significantly decreased cell survival and migration in drug-sensitive EOC cells but not drug-resistant cells. AZD4547 significantly decreased tumor weight in xenograft models of drug-sensitive A2780 and SKOV3ip1 cells and in a PDX with drug sensitivity but not in models with drug-resistant A2780-CP20 and SKOV3-TR cells. Furthermore, c-Met expression was high in SKOV3-TR and HeyA8-MDR cells, and co-administration of SU11274 and AZD4547 synergistically induced cell death. In addition, expressions of FGF19 and FGFR4 were high in A2780-CP20 cells. Combining AZD4547 with FGF19 siRNA or with a selective FGFR4 inhibitor led to significantly reduced cell proliferation in A2780-CP20 cells.

CONCLUSIONS

This study showed that AZD4547 has significant anti-cancer effects in drug-sensitive cells and PDX models but not in drug-resistant EOC cells. In drug-resistant cells, the expression level of c-Met or FGF19/FGFR4 may be a predictive biomarker for AZD4547 treatment response, and a combination strategy of drugs targeting c-Met or FGF19/FGFR4 together with AZD4547 may be an effective therapeutic strategy for EOC.

The FGF/FGFR signalling mediated anti-cancer drug resistance and therapeutic intervention

Fibroblast Growth Factor (FGF) ligands and their receptors are crucial factors driving chemoresistance in several malignancies, challenging the efficacy of currently available anti-cancer drugs. The Fibroblast growth factor/receptor (FGF/FGFR) signalling malfunctions in tumor cells, resulting in a range of molecular pathways that may impact its drug effectiveness. Deregulation of cell signalling is critical since it can enhance tumor growth and metastasis. Overexpression and mutation of FGF/FGFR induce regulatory changes in the signalling pathways. Chromosomal translocation facilitating FGFR fusion production aggravates drug resistance. Apoptosis is inhibited by FGFR-activated signalling pathways, reducing multiple anti-cancer medications' destructive impacts. Angiogenesis and epithelial-mesenchymal transition (EMT) are facilitated by FGFRs-dependent signalling, which correlates with drug resistance and enhances metastasis. Further, lysosome-mediated drug sequestration is another prominent method of resistance. Inhibition of FGF/FGFR by following a plethora of therapeutic approaches such as covalent and multitarget inhibitors, ligand traps, monoclonal antibodies, recombinant FGFs, combination therapy, and targeting lysosomes and micro RNAs would be helpful. As a result, FGF/FGFR suppression treatment options are evolving nowadays. To increase positive impacts, the processes underpinning the FGF/FGFR axis' role in developing drug resistance need to be clarified, emphasizing the need for more studies to develop novel therapeutic options to address this significant problem. Communicated by Ramaswamy H. Sarma.

Development of selective FGFR1 degraders using a Rapid synthesis of proteolysis targeting Chimera (Rapid-TAC) platform

Proteolysis Targeting Chimera (PROTAC) has emerged as a novel therapeutic strategy. The major bottleneck for the development of PROTACs is the need to screen multiple parameters to create an effective degrader. It often involves the synthesis of dozens to hundreds of compounds one by one through a tedious process. We have developed a two-stage approach that allows for the rapid synthesis of PROTACs (Rapid-TAC) using preassembled building blocks to screen multiple parameters simultaneously. We herein report the application of this method to the development of PROTACs for FGFR, a challenging membrane protein target. In the first stage, we prepared 24 potential PROTACs quickly from a hydrazide-containing FGFR inhibitor and our previously reported VHL and CRBN ligand library bearing various linkers and an aldehyde functional group. These 24 PROTACs were then directly used for screening in cellular assay for protein degradation. Multiple hits were identified from the initial screening. We then prepared the corresponding stable analogues by replacing the hydrolytic labile acylhydrazone motif with an amide in the second stage. Among them, PROTAC LG1188 was identified as a potent and selective FGFR1 degrader.

Identification of Pyridinyltriazine Derivatives as Potent panFGFR Inhibitors against Gatekeeper Mutants for Overcoming Drug Resistance

Although FGFR inhibitors hold promise in treating various cancers, resistance to the FGFR inhibitors caused by acquired secondary mutations has emerged. To discover novel FGFR inhibitors capable of inhibiting FGFR mutations, including gatekeeper mutations, we designed and synthesized several new pyridinyltriazine derivatives. A structure-activity relationship (SAR) study led to the identification of 17a as a highly potent panFGFR inhibitor against wild-type and mutant FGFRs. Notably, 17a is superior to infigratinib in terms of kinase-inhibitory and cellular activities, especially against V555M-FGFR3. Molecular dynamics simulations provide a clear understanding of why pyridinyltraizine derivative 17a possesses activity against V555M-FGFR3. Moreover, 17a significantly suppresses proliferation of cancer cells harboring FGFR mutations via FGFR signaling blockade, cell cycle arrest, and apoptosis. Furthermore, 17a and 17b exhibited remarkable efficacies in TEL-V555M-FGFR3 Ba/F3 xenograft mouse model and 17a is more efficacious than infigratinib. This study provides new insight into the design of novel FGFR inhibitors that are active against FGFR mutants.

Fibroblast Growth Factor Receptor 1-4 Genetic Aberrations as Clinically Relevant Biomarkers in Squamous Cell Lung Cancer

Fibroblast growth factor receptor (FGFR) inhibitors (FGFRis) are a potential therapeutic option for squamous non-small cell lung cancer (Sq-NSCLC). Because appropriate patient selection is needed for targeted therapy, molecular profiling is key to discovering candidate biomarker(s). Multiple FGFR aberrations are present in Sq-NSCLC tumors-alterations (mutations and fusions), amplification and mRNA/protein overexpression-but their predictive potential is unclear. Although FGFR1 amplification reliability was unsatisfactory, FGFR mRNA overexpression, mutations, and fusions are promising. However, currently their discriminatory power is insufficient, and the available clinical data are from small groups of Sq-NSCLC patients. Here, we focus on FGFR aberrations as predictive biomarkers for FGFR-targeting agents in Sq-NSCLC. Known and suggested molecular determinants of FGFRi resistance are also discussed.

Hypocrellin A exerts antitumor effects by inhibiting the FGFR1 signaling pathway in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) accounts for approximately 85% of lung cancer, which is the deadliest form of cancer worldwide. Recent studies have shown that genes in the fibroblast growth factor (FGF) family are highly mutated in lung cancer, and fibroblast growth factor receptor 1 (FGFR1) has been found to be involved in various cancers, including lung cancer, suggesting that FGFR1 is a valid therapeutic target. Hypocrellin A (HA), a molecule with multiple biological activities, has been shown to influence cancer growth, but the specific mechanisms of its antitumor action have not been fully explored.

METHODS

MTT, colony formation, wound healing, transwell cell invasion and EdU cell proliferation assays were performed upon HA treatment of three NSCLC cell lines, H460, PC-9 and H1975. Hoechst 33258 staining and caspase 3 activity assays were carried out to investigate the impact of HA on apoptosis in these cells. Molecular docking and surface plasmon resonance were conducted to assess binding of HA to FGFR1. A mouse tumor model was used to detect the NSCLC-inhibitory ability of HA in vivo.

RESULTS

Through in vitro assays, HA was shown to negatively impact cell viability, migration, invasion and promote apoptosis in three human NSCLC cell line models. HA was shown to bind to FGFR1 and to inhibit its autophosphorylation and the phosphorylation of downstream signaling molecules. Inhibition of tumor growth was also demonstrated in a mouse xenograft tumor model, and no toxic effects of HA treatment were observed.

CONCLUSIONS

HA inhibits the activity of the FGFR1 and STAT3 signaling pathways. HA thus represents a potential new FGFR1-targeted treatment for NSCLC.

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

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

FGF/FGFR-Dependent Molecular Mechanisms Underlying Anti-Cancer Drug Resistance

Simple Summary

Deregulation of the FGF/FGFR axis is associated with many types of cancer and contributes to the development of chemoresistance, limiting the effectiveness of current treatment strategies. There are several mechanisms involved in this phenomenon, including cross-talks with other signaling pathways, avoidance of apoptosis, stimulation of angiogenesis, and initiation of EMT. Here, we provide an overview of current research and approaches focusing on targeting components of the FGFR/FGF signaling module to overcome drug resistance during anti-cancer therapy.

Abstract

Increased expression of both FGF proteins and their receptors observed in many cancers is often associated with the development of chemoresistance, limiting the effectiveness of currently used anti-cancer therapies. Malfunctioning of the FGF/FGFR axis in cancer cells generates a number of molecular mechanisms that may affect the sensitivity of tumors to the applied drugs. Of key importance is the deregulation of cell signaling, which can lead to increased cell proliferation, survival, and motility, and ultimately to malignancy. Signaling pathways activated by FGFRs inhibit apoptosis, reducing the cytotoxic effect of some anti-cancer drugs. FGFRs-dependent signaling may also initiate angiogenesis and EMT, which facilitates metastasis and also correlates with drug resistance. Therefore, treatment strategies based on FGF/FGFR inhibition (using receptor inhibitors, ligand traps, monoclonal antibodies, or microRNAs) appear to be extremely promising. However, this approach may lead to further development of resistance through acquisition of specific mutations, metabolism switching, and molecular cross-talks. This review brings together information on the mechanisms underlying the involvement of the FGF/FGFR axis in the generation of drug resistance in cancer and highlights the need for further research to overcome this serious problem with novel therapeutic strategies.

Intrinsic relative preference profile of pan-kinase inhibitor drug staurosporine towards the clinically occurring gatekeeper mutations in Protein Tyrosine Kinases

Protein tyrosine kinases (PTKs) have been recognized as the attractive druggable targets of various diseases including cancer. However, many PTKs are clinically observed to establish a gatekeeper mutation in the peripheral hinge section of active site, which plays a primary role in development of acquired drug resistance to kinase inhibitors. The natural product Staurosporine, an ATP-competitive reversible pan-kinase inhibitor, has been found to exhibit wild type-sparing selectivity for some PTK gatekeeper mutants. In this study, totally 23 acquired drug-resistant gatekeeper mutations harbored on 17 PTKs involved in diverse cancers were curated, from which only five amino acid types, namely Thr, Met, Val, Leu and Ile, were observed at both wild-type and mutant residues of these clinically occurring gatekeeper sites. Here, an integrative strategy that combined molecular modeling and kinase assay was described to systematically investigate the relative preference of Staurosporine towards the five gatekeeper amino acid types in real kinase context and in a psendokinase model. A kinase-free, intrinsic relative preference profile of Staurosporine to gatekeeper amino acids was created: (dispreferred) Thr⊳Val⊳Ile⊳Leu⊳Met (preferred). It is found that kinase context has no essential effect on the profile; different kinases and even psendokinase can obtain a consistent conclusion for the preference order. Theoretically, we can use the profile to predict Staurosporine response to any gatekeeper mutation between the five amino acid types in any PTK. Structural and energetic analyses revealed that the multiple-aromatic ring system of Staurosporine can form multiple noncovalent interactions with the weakly polar side chain of Met and can pack tightly or moderately against the nonpolar side chains of Val, Ile and Leu, thus stabilizing the kinase-inhibitor system (ΔU < 0), whereas the polar side chain of Thr may cause unfavorable electronegative and solvent effects with the aromatic electrons of Staurosporine, thus destabilizing the system (ΔU > 0).

GZD824 overcomes FGFR1-V561F/M mutant resistance in vitro and in vivo

Abnormallyactivated FGFR1 has been validated as a therapeutic target for differentcancers. Although a variety of FGFR inhibitors have shown benefit in manyclinical patients with FGFR1 aberration, FGFR1 mutant resistance such as V561Mmutation, has been reported. To date however, no FGFR inhibitors have beenapproved to treat patients with FGFR mutant resistance. Herein, we report that GZD824, athird generation ABL inhibitor (Phase II, China), overcomes FGFR1‐V561F/M mutant resistance in vitro and in vivo. GZD824potently suppresses FGFR1/2/3 with an IC₅₀ value of 4.14 ± 0.96, 2.77 ± 0.082, and 8.10 ± 0.15 nmol/L. It effectively overcomes FGFR1‐V561F/M and other mutantresistance in Ba/F3 stable cells (IC₅₀:8.1–55.0 nM), and effectively inhibits the growth of Ba/F3‐FGFR1‐V561F/M mutantxenograft tumors in vivo (TGI=73.4%, 49.8% at20mg/kg, p.o, q2d). GZD824may be considered to be an effective drug to treat patients with FGFR1 abnormalactivation or mutant resistance in clinical trials.

FGFR1 regulates proliferation and metastasis by targeting CCND1 in FGFR1 amplified lung cancer

Aims: The analysis of the online databases revealed that CCND1 expression is correlated with poor prognosis in LSCC. We aimed to explore the function of CCND1 in tumor progression in LSCC.Main methods: The expression of mRNA was measured using qRT-PCR. Protein expression was assessed by Western blot. Cell migration and invasion were assessed by transwell assay.Key findings: CCND1 was co-overexpressed with FGFR1 in lung cancer patients. Overexpression of CCND1 promoted LSCC cell proliferation and metastasis. FGFR1 promoted the processes of EMT through AKT/MAPK signaling by targeting CCND1 in FGFR1-amplification cell lines.Significance: IIn conclusion, our study demonstrated the regulatory mechanism between CCND1 and FGFR1 in FGFR1 amplified LSCC. Co-targeting CCND1 and FGFR1 could provide greater clinical benefits.

Targeting the Fibroblast Growth Factor Receptor (FGFR) Family in Lung Cancer

Lung cancer is the most common cause of cancer-related deaths globally. Genetic alterations, such as amplifications, mutations and translocations in the fibroblast growth factor receptor (FGFR) family have been found in non-small cell lung cancer (NSCLC) where they have a role in cancer initiation and progression. FGFR aberrations have also been identified as key compensatory bypass mechanisms of resistance to targeted therapy against mutant epidermal growth factor receptor (EGFR) and mutant Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) in lung cancer. Targeting FGFR is, therefore, of clinical relevance for this cancer type, and several selective and nonselective FGFR inhibitors have been developed in recent years. Despite promising preclinical data, clinical trials have largely shown low efficacy of these agents in lung cancer patients with FGFR alterations. Preclinical studies have highlighted the emergence of multiple intrinsic and acquired resistance mechanisms to FGFR tyrosine kinase inhibitors, which include on-target FGFR gatekeeper mutations and activation of bypass signalling pathways and alternative receptor tyrosine kinases. Here, we review the landscape of FGFR aberrations in lung cancer and the array of targeted therapies under clinical evaluation. We also discuss the current understanding of the mechanisms of resistance to FGFR-targeting compounds and therapeutic strategies to circumvent resistance. Finally, we highlight our perspectives on the development of new biomarkers for stratification and prediction of FGFR inhibitor response to enable personalisation of treatment in patients with lung cancer.

Chemical modifications of ergostane-type triterpenoids from Antrodia camphorata and their cytotoxic activities

In order to discover potential antitumor agents from natural products, chemical modifications of ergostane-type triterpenoids from Antrodia camphorata yielded ten new compounds. They include nine C-26 amide derivatives of antcin G (1) and a methyl antcin B (4) derivative with hydroxyamino groups at C-3 and C-7. Chemical structures of the new compounds were elucidated by NMR and MS analyses. Furthermore, cytotoxicities of the triterpenoid derivatives were evaluated using four human cancer cell lines (HL60, U251, SW480, and MCF-7). As a result, 1a, 1g, and 4a exhibited potent cytotoxic activities against HL60, U251, and SW480 with IC₅₀ values of 0.7 ± 0.9, 2.9 ± 1.3, and 2.2 ± 0.6 μM, respectively. Molecular docking indicates that 1a, 1g, and 4a have strong binding affinity with DNA topoisomerase IIα (-9.3, -7.9, and -7.4 kcal/mol, respectively), and that they could be potent topoisomerase IIα inhibitors.

FGFR-TKI resistance in cancer: current status and perspectives

Fibroblast growth factor receptors (FGFRs) play key roles in promoting the proliferation, differentiation, and migration of cancer cell. Inactivation of FGFRs by tyrosine kinase inhibitors (TKI) has achieved great success in tumor-targeted therapy. However, resistance to FGFR-TKI has become a concern. Here, we review the mechanisms of FGFR-TKI resistance in cancer, including gatekeeper mutations, alternative signaling pathway activation, lysosome-mediated TKI sequestration, and gene fusion. In addition, we summarize strategies to overcome resistance, including developing covalent inhibitors, developing dual-target inhibitors, adopting combination therapy, and targeting lysosomes, which will facilitate the transition to precision medicine and individualized treatment.

Dual activating FGFR1 mutations in pediatric pilomyxoid astrocytoma

BACKGROUND

Pilomyxoid astrocytomas are an aggressive subtype of astrocytoma, not graded by WHO, frequently located in hypothalamic/chiasmatic region, affecting diencephalic structures, and characterized by shorter survival and high recurrence rates. Pilomyxoid astrocytoma management remains controversial, with pathologic tissue diagnosis and relief of mass effect being the main goals of surgery while avoiding treatment-related morbidity, including vision loss, panhypopituitarism, and hypothalamic dysfunction. Chemotherapy (typically vincristine and carboplatin) in all pediatric patients and radiation therapy in pediatric patients over 5 years of age are used for treatment.

METHODS

We report clinical presentation, surgical management, and whole exome sequencing results in a pediatric patient with the subtotally resected pilomyxoid astrocytoma.

RESULTS

We identified two somatic activating missense mutations affecting FGFR1, including FGFR1 p.K656E and FGFR1 p.V561M. While the former is a known hotspot mutation that is both activating and transforming, the latter has been described as a gatekeeper mutation imparting resistance to FGFR inhibitors. Interestingly, both mutations were present with similar variant allele frequency within the tumor.

CONCLUSION

Similar variant allele frequencies of FGFR1 p.K656E and FGFR1 p.V561M mutations in our patient's tumor suggest that these mutations may have occurred at similar time points. Use of FGFR inhibitors in addition to STAT3 or PI3K/mTOR inhibition may prove a useful strategy in targeting our patient's pilomyxoid astrocytoma.

Mutational drivers of cancer cell migration and invasion

Genomic instability and mutations underlie the hallmarks of cancer-genetic alterations determine cancer cell fate by affecting cell proliferation, apoptosis and immune response, and increasing data show that mutations are involved in metastasis, a crucial event in cancer progression and a life-threatening problem in cancer patients. Invasion is the first step in the metastatic cascade, when tumour cells acquire the ability to move, penetrate into the surrounding tissue and enter lymphatic and blood vessels in order to disseminate. A role for genetic alterations in invasion is not universally accepted, with sceptics arguing that cellular motility is related only to external factors such as hypoxia, chemoattractants and the rigidity of the extracellular matrix. However, increasing evidence shows that mutations might trigger and accelerate the migration and invasion of different types of cancer cells. In this review, we summarise data from published literature on the effect of chromosomal instability and genetic mutations on cancer cell migration and invasion.

Predictive article recommendation using natural language processing and machine learning to support evidence updates in domain-specific knowledge graphs

Objectives

Describe an augmented intelligence approach to facilitate the update of evidence for associations in knowledge graphs.

Methods

New publications are filtered through multiple machine learning study classifiers, and filtered publications are combined with articles already included as evidence in the knowledge graph. The corpus is then subjected to named entity recognition, semantic dictionary mapping, term vector space modeling, pairwise similarity, and focal entity match to identify highly related publications. Subject matter experts review recommended articles to assess inclusion in the knowledge graph; discrepancies are resolved by consensus.

Results

Study classifiers achieved F-scores from 0.88 to 0.94, and similarity thresholds for each study type were determined by experimentation. Our approach reduces human literature review load by 99%, and over the past 12 months, 41% of recommendations were accepted to update the knowledge graph.

Conclusion

Integrated search and recommendation exploiting current evidence in a knowledge graph is useful for reducing human cognition load.

FGFR4: A promising therapeutic target for breast cancer and other solid tumors

The fibroblast growth factor receptor (FGFR) signaling pathway has long been known to cancer researchers because of its role in cell survival, proliferation, migration, and angiogenesis. Dysregulation of FGFR signaling is frequently reported in cancer studies, but most of these studies focus on FGFR1-3. However, there is growing evidence implicating an important and unique role of FGFR4 in oncogenesis, tumor progression, and resistance to anti-tumor therapy in multiple types of cancer. Importantly, there are several novel FGFR4-specific inhibitors in clinical trials, making FGFR4 an attractive target for further research. In this review, we focus on assessing the role of FGFR4 in cancer, with an emphasis on breast cancer. First, the structure, physiological functions and downstream signaling pathways of FGFR4 are introduced. Next, different mechanisms reported to cause aberrant FGFR4 activation and their functions in cancer are discussed, including FGFR4 overexpression, FGF ligand overexpression, FGFR4 somatic hotspot mutations, and the FGFR4 G388R single nucleotide polymorphism. Finally, ongoing and recently completed clinical trials targeting FGFRs in cancer are reviewed, highlighting the therapeutic potential of FGFR4 inhibition for the treatment of breast cancer.

mRNA Expression of FGFR1 as Potential Marker for Predicting Prognosis of Surgical Resection of Small Cell Lung Cancer may be better than Protein Expression and Gene Amplification

Purpose: Fibroblast growth factor receptor 1 (FGFR1) alterations have been described in many cancers, including lung cancer, but the role has not been elucidated specifically in small cell lung cancer (SCLC). The present study aimed to identify the frequency of FGFR1 alterations among Chinese patients with surgically resected SCLC and the association with the clinicopathological characteristics and the survival were also investigated.

Methods: FGFR1 protein expression, FGFR1 amplification, FGFR1 mutations, and messenger RNA (mRNA) levels, were determined by immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), polymerase chain reaction (PCR) and reverse transcription-polymerase chain reaction (RT-PCR), respectively in primary tumors from 33 patients with resected SCLC.

Results: 7/33(21.2%) of the specimens were positive for FGFR1 protein expression. FGFR1 amplification was identified in 4/28 cases (14.3%). If the cut-off value was determined to be 3.5, FGFR1 mRNA positivity was considered in 7/33 cases (21.2%). However, no mutation was detected in the 33 SCLC postoperative tissue specimens. No significant association was observed between FGFR1 protein expression or amplification and clinicalcharacteristics or prognosis. There was a distinct trend for mRNA level and poor prognosis, including recurrence-free survival (RFS) (p = 0.07) and overall survival (OS) (p= 0.08), but they did not reach statistical significance.

Conclusions: As novel FGFR1-targeted therapies are developed, FISH, IHC, especially mRNA were detected, which should be considered as biomarkers of FGFR1 pathway dysregulation in SCLC.

Association of the Epithelial-Mesenchymal Transition (EMT) with Cisplatin Resistance

Therapy resistance is a characteristic of cancer cells that significantly reduces the effectiveness of drugs. Despite the popularity of cisplatin (CP) as a chemotherapeutic agent, which is widely used in the treatment of various types of cancer, resistance of cancer cells to CP chemotherapy has been extensively observed. Among various reported mechanism(s), the epithelial-mesenchymal transition (EMT) process can significantly contribute to chemoresistance by converting the motionless epithelial cells into mobile mesenchymal cells and altering cell-cell adhesion as well as the cellular extracellular matrix, leading to invasion of tumor cells. By analyzing the impact of the different molecular pathways such as microRNAs, long non-coding RNAs, nuclear factor-κB (NF-ĸB), phosphoinositide 3-kinase-related protein kinase (PI3K)/Akt, mammalian target rapamycin (mTOR), and Wnt, which play an important role in resistance exhibited to CP therapy, we first give an introduction about the EMT mechanism and its role in drug resistance. We then focus specifically on the molecular pathways involved in drug resistance and the pharmacological strategies that can be used to mitigate this resistance. Overall, we highlight the various targeted signaling pathways that could be considered in future studies to pave the way for the inhibition of EMT-mediated resistance displayed by tumor cells in response to CP exposure.

Targeting FGFR in bladder cancer: ready for clinical practice?

Objective: To give a brief literature overview of current knowledge regarding FGFR inhibition in bladder cancer.Background: The deeper molecular understanding of bladder urothelial carcinoma (UC) has reshaped the diagnostic and therapeutic landscape of this malignancy. Rapid technological development, including the frequent use of next-generation sequencing (NGS) in clinical practice, has boosted identification and development of potential biomarkers and targeted therapies. Genetic aberrations in the fibroblast growth factor receptor (FGFR)-pathway may drive tumorigenesis and are considered as attractive drug targets in advanced and/or metastatic UC. Several clinical trials have been performed or are ongoing to assess the safety and efficacy of (non-)selective FGFR inhibitors in patients with advanced or metatastic UC.Results: While non-selective FGFR inhibitors have shown limited clinical response with unacceptable toxicity, selective 'pan'-FGFR inhibitors had favourable response rates with manageable toxicity. To predict response, patients were screened for FGFR aberrations using NGS after DNA/RNA extraction of UC tissue specimen or collection of ctDNA or cfDNA.Conclusion: Early clinical trials have shown promising results for targeting FGFR in advanced or metastatic UC, though these findings need to be validated in phase III trials. It seems that FGFR aberrations can be detected in ctDNA and cfDNA as efficiently as in tumour tissue, showing their potential as predictive, non-invasive liquid biomarkers.

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.

Novel activators and small-molecule inhibitors of STAT3 in cancer

Excessive activation of signal transducer and activator of transcription 3 (STAT3) signaling is observed in a subset of many cancers, making activated STAT3 a highly promising potential therapeutic target supported by multiple preclinical and clinical studies. However, early-phase clinical trials have produced mixed results with STAT3-targeted cancer therapies, revealing substantial complexity to targeting aberrant STAT3 signaling. This review discusses the diverse mechanisms of oncogenic activation of STAT3, and the small molecule inhibitors of STAT3 in cancer treatment.

Mechanisms of acquired resistance to fibroblast growth factor receptor targeted therapy

Oncogenic activation of the fibroblast growth factor receptor (FGFR) through mutations and fusions of the FGFR gene occur in a variety of different malignancies such as urothelial carcinoma and cholangiocarcinoma. Inhibition of the kinase domain of the FGFR with targeted oral FGFR inhibitors has been shown in both preclinical and early phase clinical trials to lead to meaningful reductions in tumour size and larger confirmatory randomized trials are underway. Acquired resistance to FGFR inhibition using a variety of mechanisms that includes, activation of alternate signaling pathways and expansion of tumour clones with gatekeeper mutations in the FGFR gene. This review summarizes the acquired resistance mechanisms to FGFR therapy and therapeutic approaches to circumventing resistance.

Reciprocal regulatory mechanism between miR-214-3p and FGFR1 in FGFR1-amplified lung cancer

MicroRNA (miRNA) and fibroblast growth factor receptor 1 (FGFR1) dysregulation are considered to play an important role in tumor proliferation, invasion, and metastasis. However, the regulatory mechanism between miRNAs and FGFR1 in lung cancer remains unclear and extremely critical. miR-214-3p was sharply decreased and showed a significantly negative correlation with FGFR1 in lung cancer patients (n = 30). Luciferase reporter assay confirmed that miR-214-3p could downregulate FGFR1 by directly targeting 3′-untranslated region (UTR). miR-214-3p inhibited the processes of epithelial–mesenchymal transition and Wnt/MAPK/AKT (Wnt/mitogen-activated protein kinase/AKT) signaling pathway by targeting FGFR1. Moreover, miR-214-3p not only established a negative feedback regulation loop with FGFR1 through ERK (extracellular signal-regulated kinase) but also developed a synergism with FGFR1 inhibitor AZD4547. In conclusion, our study demonstrated the regulatory mechanism between miR-214-3p and FGFR1 in lung cancer. miR-214-3p acts as a vital target in FGFR1-amplified lung cancer by forming a miR-214-3p-FGFR1-Wnt/MAPK/AKT signaling pathway network. Co-targeting miR-214-3p and FGFR1 could provide greater benefits to patients with FGFR1-amplified lung cancer.

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.

Expanding the Arsenal of FGFR Inhibitors: A Novel Chloroacetamide Derivative as a New Irreversible Agent With Anti-proliferative Activity Against FGFR1-Amplified Lung Cancer Cell Lines

Fibroblast Growth Factor Receptors (FGFR1-4) have a critical role in the progression of several human cancers, including Squamous Non-Small-Cell Lung Cancer (SQCLC). Both non-selective and selective reversible FGFR inhibitors are under clinical investigation for the treatment of patients with tumors harboring FGFR alterations. Despite their potential efficacy, the clinical development of these drugs has encountered several challenges, including toxicity, and the appearance of drug resistance. Recent efforts have been directed at development of irreversible FGFR inhibitors, which have the potential to exert superior anti-proliferative activity in tumors carrying FGFR alterations. With this in mind, we synthetized, and investigated a set of novel inhibitors possessing a warhead potentially able to covalently bind a cysteine in the P-loop of FGFR. Among them, the chloroacetamide UPR1376 resulted able to irreversible inhibit FGFR1 phosphorylation in FGFR1 over-expressing cells generated from SQCLC SKMES-1 cells. In addition, this compound inhibited cell proliferation in FGFR1-amplified H1581 cells with a potency higher than the reversible inhibitor BGJ398 (infigratinib), while sparing FGFR1 low-expressing cells. The anti-proliferative effects of UPR1376 were demonstrated in both 2D and 3D systems and were associated with the inhibition of MAPK and AKT/mTOR signaling pathways. UPR1376 inhibited cell proliferation also in two BGJ398-resistant cell clones generated from H1581 by chronic exposure to BGJ398, although at concentrations higher than those effective in the parental cells, likely due to the persistent activation of the MAPK pathway associated to NRAS amplification. Combined blockade of FGFR1 and MAPK signaling, by UPR1376 and trametinib respectively, significantly enhanced the efficacy of UPR1376, providing a means of circumventing resistance to FGFR1 inhibition. Our findings suggest that the insertion of a chloroacetamide warhead on a suitable scaffold, as exemplified by UPR1376, is a valuable strategy to develop a novel generation of FGFR inhibitors for the treatment of SQCLC patients with FGFR alterations.