FGF401, A First-In-Class Highly Selective and Potent FGFR4 Inhibitor for the Treatment of FGF19-Driven Hepatocellular Cancer

Emerging and Re-emerging Warheads for Targeted Covalent Inhibitors: An Update

Covalent inhibitors and other types of covalent modalities have seen a revival in the past two decades, with a variety of new targeted covalent drugs having been approved in recent years. A key feature of such molecules is an intrinsically reactive group, typically a weak electrophile, which enables the irreversible or reversible formation of a covalent bond with a specific amino acid of the target protein. This reactive group, often called the "warhead", is a critical determinant of the ligand's activity, selectivity, and general biological properties. In 2019, we summarized emerging and re-emerging warhead chemistries to target cysteine and other amino acids (Gehringer, M.; Laufer, S. A. J. Med. Chem. 2019, 62, 5673-5724; DOI: 10.1021/acs.jmedchem.8b01153). Since then, the field has rapidly evolved. Here we discuss the progress on covalent warheads made since our last Perspective and their application in medicinal chemistry and chemical biology.

mRNA Display Identifies Potent, Paralog-Selective Peptidic Ligands for ARID1B

The ARID1A and ARID1B subunits are mutually exclusive components of the BAF variant of SWI/SNF chromatin remodeling complexes. Loss of function mutations in ARID1A are frequently observed in various cancers, resulting in a dependency on the paralog ARID1B for cancer cell proliferation. However, ARID1B has never been targeted directly, and the high degree of sequence similarity to ARID1A poses a challenge for the development of selective binders. In this study, we used mRNA display to identify peptidic ligands that bind with nanomolar affinities to ARID1B and showed high selectivity over ARID1A. Using orthogonal biochemical, biophysical, and chemical biology tools, we demonstrate that the peptides engage two different binding pockets, one of which directly involves an ARID1B-exclusive cysteine that could allow covalent targeting by small molecules. Our findings impart the first evidence of the ligandability of ARID1B, provide valuable tools for drug discovery, and suggest opportunities for the development of selective molecules to exploit the synthetic lethal relationship between ARID1A and ARID1B in cancer.

Discovery of N-(4-((6-(3,5- Dimethoxyphenyl)-9H-purine derivatives as irreversible covalent FGFR inhibitors

Fibroblast growth factor receptor (FGFR) is an attractive target for cancer therapy, but existing FGFR inhibitors appear to hardly meet the demand for clinical application. Herein, a number of irreversible covalent FGFR inhibitors were designed and synthesized by selecting several five- and six-membered azaheterocycles as parent scaffold with different substituents to take over the hydrophobic region in the active pocket of FGFR proteins. Among the resulting target compounds, III-30 showed the most potent effect on enzyme activity inhibition and anti-proliferative activity against the tested cancer cell lines. Significantly, III-30 could inhibit the enzyme activity by achieving irreversible covalent binding with FGFR1 and FGFR4 proteins. It could also regulate FGFR-mediated signaling pathway and mitochondrial apoptotic pathway to promote cancer cell apoptosis and inhibit cancer cell invasion and metastasis. Moreover, III-30 had a good metabolic stability and showed relatively potent anti-tumor activity in the MDA-MB-231 xenograft tumor mice model.

Blocking of FGFR4 signaling by F30 inhibits hepatocellular carcinoma cell proliferation through HMOX1-dependent ferroptosis pathway

Excessive activation of FGF19/fibroblast growth factor receptor 4 (FGFR4) signaling is associated with poor survival of patients with hepatocellular carcinoma (HCC). FGFR4 inhibitors show promise for HCC treatment. F30, an indazole derivative designed through computer-aided drug design targeting FGFR4, demonstrated anti-HCC activity as described in our previous studies. However, the precise molecular mechanisms underlying F30's anticancer effects remain largely unexplored. We report here that F30 could effectively induce ferroptosis in HCC cells. The concentrations of cellular ferrous iron, the peroxidation of cell membranes and the homeostasis of reduced glutathione (GSH)/oxidized glutathione disulfide (GSSG) were dysregulated by F30, thereby affecting cellular redox status. Induction of ferroptosis in HCC by F30 was inhibited by specific ferroptosis inhibitor ferrostatin-1. F30 upregulates various ferroptosis-related genes, including the heme oxygenase enzymes 1 (HMOX1), a key mediator of redox regulation. Surprisingly, F30-induced ferroptosis in HCC is dependent on HMOX1. The dysregulation of cellular ferrous iron concentrations and cell membrane peroxidation was rescued when knocking down HMOX1 with specific small interfering RNA. These findings shed light on the molecular mechanisms underlying FGFR4-targeting F30's anti-HCC effects and suggest that FGFR4 inactivation could be beneficial for HCC treatment involving ferroptosis.

Lenvatinib in hepatocellular carcinoma: Resistance mechanisms and strategies for improved efficacy

Hepatocellular carcinoma (HCC), one of the most prevalent and destructive causes of cancer-related deaths worldwide, approximately 70% of patients with HCC exhibit advanced disease at diagnosis, limiting the potential for radical treatment. For such patients, lenvatinib, a long-awaited alternative to sorafenib for first-line targeted therapy, has become a key treatment. Unfortunately, despite some progress, the prognosis for advanced HCC remains poor because of drug resistance development. However, the molecular mechanisms underlying lenvatinib resistance and ways to relief drug resistance in HCC are largely unknown and lack of systematic summary; thus, this review not only aims to explore factors contributing to lenvatinib resistance in HCC, but more importantly, summary potential methods to conquer or mitigate the resistance. The results suggest that abnormal activation of pathways, drug transport, epigenetics, tumour microenvironment, cancer stem cells, regulated cell death, epithelial-mesenchymal transition, and other mechanisms are involved in the development of lenvatinib resistance in HCC and subsequent HCC progression. To improve the therapeutic outcomes of lenvatinib, inhibiting acquired resistance, combined therapies, and nano-delivery carriers may be possible approaches.

FGFR-targeted therapeutics: clinical activity, mechanisms of resistance and new directions

Fibroblast growth factor (FGF) signalling via FGF receptors (FGFR1-4) orchestrates fetal development and contributes to tissue and whole-body homeostasis, but can also promote tumorigenesis. Various agents, including pan-FGFR inhibitors (erdafitinib and futibatinib), FGFR1/2/3 inhibitors (infigratinib and pemigatinib), as well as a range of more-specific agents, have been developed and several have entered clinical use. Erdafitinib is approved for patients with urothelial carcinoma harbouring FGFR2/3 alterations, and futibatinib and pemigatinib are approved for patients with cholangiocarcinoma harbouring FGFR2 fusions and/or rearrangements. Clinical benefit from these agents is in part limited by hyperphosphataemia owing to off-target inhibition of FGFR1 as well as the emergence of resistance mutations in FGFR genes, activation of bypass signalling pathways, concurrent TP53 alterations and possibly epithelial-mesenchymal transition-related isoform switching. The next generation of small-molecule inhibitors, such as lirafugratinib and LOXO-435, and the FGFR2-specific antibody bemarituzumab are expected to have a reduced risk of hyperphosphataemia and the ability to overcome certain resistance mutations. In this Review, we describe the development and current clinical role of FGFR inhibitors and provide perspective on future research directions including expansion of the therapeutic indications for use of FGFR inhibitors, combination of these agents with immune-checkpoint inhibitors and the application of novel technologies, such as artificial intelligence.

Targeting the FGF19-FGFR4 pathway for cholestatic, metabolic, and cancerous diseases

Human fibroblast growth factor 19 (FGF19, or FGF15 in rodents) plays a central role in controlling bile acid (BA) synthesis through a negative feedback mechanism. This process involves a postprandial crosstalk between the BA-activated ileal farnesoid X receptor and the hepatic Klotho beta (KLB) coreceptor complexed with fibrobalst growth factor receptor 4 (FGFR4) kinase. Additionally, FGF19 regulates glucose, lipid, and energy metabolism by coordinating responses from functional KLB and FGFR1-3 receptor complexes on the periphery. Pharmacologically, native FGF19 or its analogs decrease elevated BA levels, fat content, and collateral tissue damage. This makes them effective in treating both cholestatic diseases such as primary biliary or sclerosing cholangitis (PBC or PSC) and metabolic abnormalities such as nonalcoholic steatohepatitis (NASH). However, chronic administration of FGF19 drives oncogenesis in mice by activating the FGFR4-dependent mitogenic or hepatic regenerative pathway, which could be a concern in humans. Agents that block FGF19 or FGFR4 signaling have shown great potency in preventing FGF19-responsive hepatocellular carcinoma (HCC) development in animal models. Recent phase 1/2 clinical trials have demonstrated promising results for several FGF19-based agents in selectively treating patients with PBC, PSC, NASH, or HCC. This review aims to provide an update on the clinical development of both analogs and antagonists targeting the FGF19-FGFR4 signaling pathway for patients with cholestatic, metabolic, and cancer diseases. We will also analyze potential safety and mechanistic concerns that should guide future research and advanced trials.

Discovery of 6-Formylpyridyl Urea Derivatives as Potent Reversible-Covalent Fibroblast Growth Factor Receptor 4 Inhibitors with Improved Anti-Hepatocellular Carcinoma Activity

Fibroblast growth factor receptor 4 (FGFR4) has been considered as a potential anticancer target due to FGF19/FGFR4 mediated aberrant signaling in hepatocellular carcinoma (HCC). Several FGFR4 inhibitors have been reported, but none have gained approval. Herein, a series of 5-formyl-pyrrolo[3,2-b]pyridine-3-carboxamides and a series of 6-formylpyridyl ureas were characterized as selective reversible-covalent FGFR4 inhibitors. The representative 6-formylpyridyl urea 8z exhibited excellent potency against FGFR4WT, FGFR4V550L, and FGFR4V550M with IC50 values of 16.3, 12.6, and 57.3 nM, respectively. It also potently suppressed proliferation of Ba/F3 cells driven by FGFR4WT, FGFR4V550L, and FGFR4V550M, and FGFR4-dependent Hep3B and Huh7 HCC cells, with IC50 values of 1.2, 13.5, 64.5, 15.0, and 20.4 nM, respectively. Furthermore, 8z displayed desirable microsomal stability and significant in vivo efficacy in the Huh7 HCC cancer xenograft model in nude mice. The study provides a promising new lead for anticancer drug discovery directed toward overcoming FGFR4 gatekeeper mutation mediated resistance in HCC patients.

EGFR Inhibition Overcomes Resistance to FGFR4 Inhibition and Potentiates FGFR4 Inhibitor Therapy in Hepatocellular Carcinoma

Aberrant activation of the FGF19-FGFR4 signaling pathway plays an essential role in the tumorigenesis of hepatocellular carcinoma (HCC). As such, FGFR4 inhibition has emerged as a novel therapeutic option for the treatment of HCC and has shown preliminary efficacy in recent clinical trials for patients exhibiting aberrant FGF19 expression. Resistance to kinase inhibitors is common in oncology, presenting a major challenge in the clinical treatment process. Hence, we investigated the potential mechanisms mediating and causing resistance to FGFR4 inhibition in HCC. Upon the successful establishment of a battery of cellular models developing resistance to FGFR4 inhibitors, we have identified the activation of EGFR, MAPK, and AKT signaling as the primary mechanisms mediating the acquired resistance. Combination of inhibitors against EGFR or its downstream components restored sensitivity to FGFR4 inhibitors. In parental HCC cell lines, EGF treatment also resulted in resistance to FGFR4 inhibitors. This resistance was effectively reverted by inhibitors of the EGFR signaling pathway, suggesting that EGFR activation is a potential cause of intrinsic resistance. We further confirmed the above findings in vivo in mouse xenograft tumor models. Genomic analysis of patient samples from The Cancer Genome Atlas confirmed that a segment of patients with HCC harboring FGF19 overexpression indeed exhibited increased activation of EGFR signaling. These findings conclusively indicate that both induced and innate activation of EGFR could mediate resistance to FGFR4 inhibition, suggesting that dual blockade of EGFR and FGFR4 may be a promising future therapeutic strategy for the treatment of FGF19-FGFR4 altered HCC.

Gypsogenin Battling for a Front Position in the Pentacyclic Triterpenes Game of Thrones on Anti-Cancer Therapy: A Critical Review-Dedicated to the Memory of Professor Hanaa M. Rady

In the last decade, gypsogenin has attracted widespread attention from medicinal chemists by virtue of its prominent anti-cancer potential. Despite its late identification, gypsogenin has proved itself as a new anti-proliferative player battling for a frontline position among other classic pentacyclic triterpenes such as oleanolic acid, glycyrrhetinic acid, ursolic acid, betulinic acid, and celastrol. Herein, we present the most important reactions of gypsogenin via modification of its four functional groups. Furthermore, we demonstrate insights into the anti-cancer activity of gypsogenin and its semisynthetic derivatives and go further by introducing our perspective to judiciously guide the prospective rational design. The present article opens a new venue for a better exploitation of gypsogenin chemical entity as a lead compound in cancer chemotherapy. To the best of our knowledge, this is the first review article exploring the anti-cancer activity of gypsogenin derivatives.

Design, synthesis and biological evaluation of indazole derivatives as selective covalent inhibitors of FGFR4 in wild-type and gatekeeper mutants

Fibroblast growth factor receptor 4 (FGFR4) has been proved to be an effective target for cancer therapy. Aberration in FGF19/FGFR4 signaling is oncogenic driving force in human hepatocellular carcinoma (HCC). FGFR4 gatekeeper mutations induced acquired resistance remains an unmet clinical challenge for HCC treatment. In this study, a series of 1H-indazole derivatives were designed and synthesized as new irreversible inhibitors of wild-type and gatekeeper mutant FGFR4. These new derivatives showed significant FGFR4 inhibitory and antitumor activities, among which compound 27i was demonstrated to be the most potent compound (FGFR4 IC₅₀ = 2.4 nM). Remarkably, compound 27i exhibited no activity against a panel of 381 kinases at 1 μM. Additionally, compound 27i displayed nanomolar IC₅₀s against huh7 (IC₅₀ = 21 nM) and two mutant cell lines, BaF3/ETV6-FGFR4-V550L and BaF3/ETV6-FGFR4-N535K (IC₅₀ = 2.5/171 nM). Meanwhile, compound 27i exhibited potent antitumor potency (TGI: 83.0%, 40 mg/kg, BID) in Huh7 xenograft mouse models with no obvious toxicity observed. Overall, compound 27i was identified as a promising preclinical candidate for overcoming FGFR4 gatekeeper mutations for HCC treatment.

An update on the discovery and development of reversible covalent inhibitors

Small molecule drugs that covalently bind irreversibly to their target proteins have several advantages over conventional reversible inhibitors. They include increased duration of action, less-frequent drug dosing, reduced pharmacokinetic sensitivity, and the potential to target intractable shallow binding sites. Despite these advantages, the key challenges of irreversible covalent drugs are their potential for off-target toxicities and immunogenicity risks. Incorporating reversibility into covalent drugs would lead to less off-target toxicity by forming reversible adducts with off-target proteins and thus reducing the risk of idiosyncratic toxicities caused by the permanent modification of proteins, which leads to higher levels of potential haptens. Herein, we systematically review electrophilic warheads employed during the development of reversible covalent drugs. We hope the structural insights of electrophilic warheads would provide helpful information to medicinal chemists and aid in designing covalent drugs with better on-target selectivity and improved safety.

Graphical Abstract

Design, synthesis, and anticancer evaluation of arylurea derivatives as potent and selective type II irreversible covalent FGFR4 inhibitors

Aberrant FGF19/FGFR4 signaling has been demonstrated to be an oncogenic driver of growth and survival in human hepatocellular carcinoma (HCC). At present, the development of FGFR4-specific drugs has become a hotspot in tumor-targeted therapy research. However, no selective FGFR4 inhibitors have been approved by FDA so far. Currently, most of the reported FGFR4 inhibitors that use a covalent targeting strategy to be selective are typical type I inhibitors with a single type. Here, based on Ponatinib, we designed and synthesized a series of arylurea derivatives as novel type II irreversible covalent inhibitors of FGFR4. Among them, the representative compound 6v exhibited an IC₅₀ value of 74 nM against FGFR4 and antiproliferative potency of 0.25 μM and 0.22 μM against Huh7 and Hep3B cell lines. Western blotting results showed that compound 6v significantly inhibited the phosphorylation of FGFR4 and its downstream signaling factors AKT and ERK in a dose-dependent manner in Hep3B cell. These results showed that this series of compounds, as type II irreversible FGFR4 inhibitors, are worthy of further research and structural optimization.

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

ABSTRACT 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.

Fibroblast growth factor receptor type 4 as a potential therapeutic target in clear cell renal cell carcinoma

BACKGROUND

Several clear cell renal cell carcinoma (ccRCC) cases harbour fibroblast growth factor receptor 4 (FGFR4) gene copy number (CN) gains. In this study, we investigated the functional contribution of FGFR4 CN amplification in ccRCC.

METHODS

The correlation between FGFR4 CN determined via real-time PCR and protein expression evaluated using western blotting and immunohistochemistry was assessed in ccRCC cell lines (A498, A704, and 769-P), a papillary RCC cell line (ACHN), and clinical ccRCC specimens. The effect of FGFR4 inhibition on ccRCC cell proliferation and survival was assessed via either RNA interference or using the selective FGFR4 inhibitor BLU9931, followed by MTS assays, western blotting, and flow cytometry. To investigate whether FGFR4 is a potential therapeutic target, a xenograft mouse model was administered BLU9931.

RESULTS

60% of ccRCC surgical specimens harboured an FGFR4 CN amplification. FGFR4 CN was positively correlated with its protein expression. All ccRCC cell lines harboured FGFR4 CN amplifications, whereas ACHN did not. FGFR4 silencing or inhibition attenuated intracellular signal transduction pathways, resulting in apoptosis and suppressed proliferation in ccRCC cell lines. BLU9931 suppressed tumours at a tolerable dose in the mouse model.

CONCLUSION

FGFR4 contributes to ccRCC cell proliferation and survival following FGFR4 amplification, making it a potential therapeutic target for ccRCC.

First-in-Human Study of INCB062079, a Fibroblast Growth Factor Receptor 4 Inhibitor, in Patients with Advanced Solid Tumors

INTRODUCTION

Fibroblast growth factor receptor (FGFR)-4/FGF19 pathway dysregulation is implicated in hepatobiliary and other solid tumors. INCB062079, an oral, selective, FGFR4 inhibitor, inhibits growth in FGF19/FGFR4-driven liver cancer models.

METHODS

This was a two-part, phase I study (NCT03144661) in previously treated patients with advanced solid tumors. The primary objective was to determine safety, tolerability, and maximum tolerated dose (MTD), while secondary objectives included pharmacokinetics, pharmacodynamics (plasma FGF19; bile acid salts/7α-hydroxy-4-cholesten-3-one [C4] levels), and preliminary efficacy. In Part 1, patients received INCB062079 starting at 10 mg once daily, with 3 + 3 dose escalation. Part 2 (dose expansion) was not conducted because of study termination.

RESULTS

Twenty-three patients were treated (hepatobiliary, n = 11; ovarian, n = 9; other, n = 3). Among six patients receiving 15 mg twice daily, two patients had dose-limiting toxicities (DLTs; grade 3 diarrhea, grade 3 transaminitis). Both had high pretreatment C4 concentrations, prompting a protocol amendment requiring pretreatment C4 concentrations < 40.9 ng/mL and concomitant prophylactic bile acid sequestrant treatment. No additional DLTs were reported at 10 and 15 mg twice daily; higher doses were not assessed. The most common toxicity was diarrhea (60.9%). INCB062079 exposure was dose-proportional; FGF19 and bile acid/C4 concentrations increased with exposure. One partial response was achieved (15 mg twice daily; ovarian cancer; FGF/FGFR status unknown; duration of response, 7.5 months); two patients had stable disease.

CONCLUSIONS

With C4 cut-off and prophylactic bile acid sequestrant implementation, INCB062079 demonstrated a manageable safety profile and evidence of target inhibition. In view of the rarity of FGF19/FGFR4 alterations and slow patient accrual, the study was terminated before establishing an MTD.

Phase 1 dose escalation study of FGFR4 inhibitor in combination with pembrolizumab in advanced solid tumors patients

OBJECTIVE

Inhibition of fibroblast growth factor (FGF) 19-FGF Receptor 4 (FGFR4) signaling demonstrates potent anticancer activity. EVER4010001 is a highly selective FGFR4 inhibitor and pembrolizumab is approved for the treatment of several solid tumors. This study determined the maximum tolerated dose (MTD), recommended Phase 2 dose (RP2D), pharmacokinetics, safety, and preliminary efficacy of EVER4010001 plus pembrolizumab in patients with advanced solid tumors.

METHODS

This Phase 1, multicenter, open-label study enrolled 19 Asian-Chinese patients (57.9% male: median age 58 years) with advanced solid tumors. For "3+3" dose escalation, 3-6 patients received treatment at each dose level (EVER4010001 40, 60, 80, or 100 mg twice daily [BID] plus pembrolizumab 200 mg every 3 weeks).

RESULTS

At the data cutoff (August 12, 2021), no dose-limiting toxicities (DLTs) were reported at 40 mg-80 mg. At 100 mg, 2 (40.0%) patients had 3 DLTs within the 28-day DLT observation period after first administration. Median time to peak EVER4010001 concentration (T_max ) was 0.55-1.03 hours. Mean terminal EVER4010001 half-life (T_1/2 ) was 4.00-4.92 hours. The area under the concentration-time curve (AUC_0-t ) and maximum observed concentration (C_max ) ranged from 2370.87-5475.77 hour*ng/ml and 606.07-1348.86 ng/ml, respectively. The most common EVER4010001-related treatment-emergent adverse events were diarrhea (94.7%), increased aspartate aminotransferase (57.9%), and increased alanine aminotransferase (47.4%).

CONCLUSION

Eighty milligrams BID was the MTD and RP2D for EVER4010001 plus pembrolizumab. Efficacy results were promising, and no new safety risks were reported, justifying the Phase 2 portion of this study.

Integration of Pharmacokinetics, Pharmacodynamics, Safety, and Efficacy into Model-Informed Dose Selection in Oncology First-in-Human Study: A Case of Roblitinib (FGF401)

Model-informed dose selection has been drawing increasing interest in oncology early clinical development. The current paper describes the example of FGF401, a selective fibroblast growth factor receptor 4 (FGFR4) inhibitor, in which a comprehensive modeling and simulation (M&S) framework, using both pharmacometrics and statistical methods, was established during its first-in-human clinical development using the totality of pharmacokinetics (PK), pharmacodynamic (PD) biomarkers, and safety and efficacy data in patients with cancer. These M&S results were used to inform FGF401 dose selection for future development. A two-compartment population PK (PopPK) model with a delayed 0-order absorption and linear elimination adequately described FGF401 PK. Indirect PopPK/PD models including a precursor compartment were independently established for two biomarkers: circulating FGF19 and 7α-hydroxy-4-cholesten-3-one (C4). Model simulations indicated a close-to-maximal PD effect achieved at the clinical exposure range. Time-to-progression was analyzed by Kaplan-Meier method which favored a trough concentration (C_trough )-driven efficacy requiring C_trough above a threshold close to the drug concentration producing 90% inhibition of phospho-FGFR4. Clinical tumor growth inhibition was described by a PopPK/PD model that reproduced the dose-dependent effect on tumor growth. Exposure-safety analyses on the expected on-target adverse events, including elevation of aspartate aminotransferase and diarrhea, indicated a lack of clinically relevant relationship with FGF401 exposure. Simulations from an indirect PopPK/PD model established for alanine aminotransferase, including a chain of three precursor compartments, further supported that maximal target inhibition was achieved and there was a lack of safety-exposure relationship. This M&S framework supported a dose selection of 120 mg once daily fasted or with a low-fat meal and provides a practical example that might be applied broadly in oncology early clinical development.

Advances in covalent drug discovery

Covalent drugs have been used to treat diseases for more than a century, but tools that facilitate the rational design of covalent drugs have emerged more recently. The purposeful addition of reactive functional groups to existing ligands can enable potent and selective inhibition of target proteins, as demonstrated by the covalent epidermal growth factor receptor (EGFR) and Bruton's tyrosine kinase (BTK) inhibitors used to treat various cancers. Moreover, the identification of covalent ligands through 'electrophile-first' approaches has also led to the discovery of covalent drugs, such as covalent inhibitors for KRAS(G12C) and SARS-CoV-2 main protease. In particular, the discovery of KRAS(G12C) inhibitors validates the use of covalent screening technologies, which have become more powerful and widespread over the past decade. Chemoproteomics platforms have emerged to complement covalent ligand screening and assist in ligand discovery, selectivity profiling and target identification. This Review showcases covalent drug discovery milestones with emphasis on the lessons learned from these programmes and how an evolving toolbox of covalent drug discovery techniques facilitates success in this field.

Generation of multicellular tumor spheroids with micro-well array for anticancer drug combination screening based on a valuable biomarker of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly malignant tumor with a poor prognosis. More than 30% of patients with diagnosed HCC have abnormally high expression of fibroblast growth factor receptor 4 (FGFR4). Currently, clinical trials for a variety of FGFR4-specific inhibitors have started. However, the effect of these inhibitors is not ideal, and it is necessary to find a drug combination to synergistically exert anti-tumor effects. We found strong correlations between FGFR4 and HCC clinicopathological characteristics in the present study. After grouping patients according to FGFR4 expression, the key gene signatures were inputted the drug-gene related databases, which predicted several potential drug candidates. More importantly, to achieve the reliable and high throughput drug cytotoxicity assessment, we developed an efficient and reproducible agarose hydrogel microwells to generate uniform-sized multicellular tumor spheroids, which provide better mimicry of conventional solid tumors that can precisely represent anticancer drug candidates' effects. Using high content screening, we quickly evaluated the enhanced anti-tumor effects of these combinations. Finally, we demonstrated that Parthenolide is a potential drug that can significantly enhance the clinical efficacy of FGFR4 receptor inhibitors. In general, we offered a new therapeutic way for FGFR4 positive HCC patients.

Strategies to inhibit FGFR4 V550L-driven rhabdomyosarcoma

BACKGROUND

Rhabdomyosarcoma (RMS) is a paediatric cancer driven either by fusion proteins (e.g., PAX3-FOXO1) or by mutations in key signalling molecules (e.g., RAS or FGFR4). Despite the latter providing opportunities for precision medicine approaches in RMS, there are currently no such treatments implemented in the clinic.

METHODS

We evaluated biologic properties and targeting strategies for the FGFR4 V550L activating mutation in RMS559 cells, which have a high allelic fraction of this mutation and are oncogenically dependent on FGFR4 signalling. Signalling and trafficking of FGFR4 V550L were characterised by confocal microscopy and proteomics. Drug effects were determined by live-cell imaging, MTS assay, and in a mouse model.

RESULTS

Among recently developed FGFR4-specific inhibitors, FGF401 inhibited FGFR4 V550L-dependent signalling and cell proliferation at low nanomolar concentrations. Two other FGFR4 inhibitors, BLU9931 and H3B6527, lacked potent activity against FGFR4 V550L. Alternate targeting strategies were identified by RMS559 phosphoproteomic analyses, demonstrating that RAS/MAPK and PI3K/AKT are essential druggable pathways downstream of FGFR4 V550L. Furthermore, we found that FGFR4 V550L is HSP90-dependent, and HSP90 inhibitors efficiently impeded RMS559 proliferation. In a RMS559 mouse xenograft model, the pan-FGFR inhibitor, LY2874455, did not efficiently inhibit growth, whereas FGF401 potently abrogated growth.

CONCLUSIONS

Our results pave the way for precision medicine approaches against FGFR4 V550L-driven RMS.

Design, Synthesis, and Biological Evaluation of 5-Formyl-pyrrolo[3,2-b]pyridine-3-carboxamides as New Selective, Potent, and Reversible-Covalent FGFR4 Inhibitors

The FGF19-FGFR4 signaling pathway has been extensively studied as a promising target for the treatment of hepatocellular carcinoma (HCC). Several FGFR4-selective inhibitors have been developed, but none of them receives approval. Additionally, acquired resistance caused by FGFR4 gatekeeper mutations is emerging as a serious limitation for these targeted therapies. Herein, we report a novel series of 5-formyl-pyrrolo[3,2-b]pyridine derivatives as new reversible-covalent inhibitors targeting wild-type and gatekeeper mutant variants of FGFR4 kinase. The representative compound 10z exhibited single-digit nanomolar activity against wild-type FGFR4 and the FGFR4V550L/M mutant variants in biochemical and Ba/F3 cellular assays, while sparing FGFR1/2/3. Furthermore, 10z showed significant antiproliferative activity against Hep3B, JHH-7, and HuH-7 HCC cells with IC50 values of 37, 32, and 94 nM, respectively. MALDI-TOF-MS and X-ray protein crystallography studies were consistent with 10z acting as a reversible-covalent inhibitor of FGFR4, serving as a promising lead compound for further anticancer drug development.

Isoform-specific inhibition of FGFR signaling achieved by a de-novo-designed mini-protein

Cellular signaling by fibroblast growth factor receptors (FGFRs) is a highly regulated process mediated by specific interactions between distinct subsets of fibroblast growth factor (FGF) ligands and two FGFR isoforms generated by alternative splicing: an epithelial b- and mesenchymal c-isoforms. Here, we investigate the properties of a mini-protein, mb7, developed by an in silico design strategy to bind to the ligand-binding region of FGFR2. We describe structural, biophysical, and cellular analyses demonstrating that mb7 binds with high affinity to the c-isoforms of FGFR, resulting in inhibition of cellular signaling induced by a subset of FGFs that preferentially activate c-isoforms of FGFR. Notably, as mb7 blocks interaction between FGFR with Klotho proteins, it functions as an antagonist of the metabolic hormones FGF19 and FGF21, providing mechanistic insights and strategies for the development of therapeutics for diseases driven by aberrantly activated FGFRs.

Park et al. show that a de-novo-designed mini-protein, mb7, can specifically recognize c-isoforms of FGFRs. By masking the regions of FGFR that are critical for the FGFR activation, mb7 can potently inhibit cellular signaling by a subset of FGFs that preferentially activate FGFR c-isoform signaling.

Prognostic Role of Molecular and Imaging Biomarkers for Predicting Advanced Hepatocellular Carcinoma Treatment Efficacy

Simple Summary

Molecular biomarkers play a marginal role in clinical practice for hepatocellular carcinoma (HCC) diagnosis, surveillance and treatment monitoring. Radiological biomarker: alpha-fetoprotein is still a lone protagonist in this field. The potential role of molecular biomarkers in the assessment of prognosis and treatment results could reduce the health costs faced by standard radiology. The majority of efforts are oriented towards early HCC detection, but the field faces an important challenge to find adequate biomarkers for advanced HCC management.

Abstract

Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide and the fourth cause of tumor-related death. Imaging biomarkers are based on computed tomography, magnetic resonance, and contrast-enhanced ultrasound, and are widely applied in HCC diagnosis and treatment monitoring. Unfortunately, in the field of molecular biomarkers, alpha-fetoprotein (AFP) is still the only recognized tool for HCC surveillance in both diagnostic and follow-up purposes. Other molecular biomarkers have little roles in clinical practice regarding HCC, mainly for the detection of early-stage HCC, monitoring the response to treatments and analyzing tumor prognosis. In the last decades no important improvements have been achieved in this field and imaging biomarkers maintain the primacy in HCC diagnosis and follow-up. Despite the still inconsistent role of molecular biomarkers in surveillance and early HCC detection, they could play an outstanding role in prognosis estimation and treatment monitoring with a potential reduction in health costs faced by standard radiology. An important challenge resides in identifying sufficiently sensitive and specific biomarkers for advanced HCC for prognostic evaluation and detection of tumor progression, overcoming imaging biomarker sensitivity. The aim of this review is to analyze the current molecular and imaging biomarkers in advanced HCC.

Comprehensive analysis of the prognostic value and immune infiltration of FGFR family members in gastric cancer

Background

Fibroblast growth factor receptors (FGFRs) modulate numerous cellular processes in tumor cells and tumor microenvironment. However, the effect of FGFRs on tumor prognosis and tumor-infiltrating lymphocytes in gastric cancer (GC) remains controversial.

Methods

The expression of four different types of FGFRs was analyzed via GEPIA, TCGA-STAD, and GTEX databases and our 27 pairs of GC tumor samples and the adjacent normal tissue. Furthermore, the Kaplan–Meier plot and the TCGA database were utilized to assess the association of FGFRs with clinical prognosis. The R software was used to evaluate FGFRs co-expression genes with GO/KEGG Pathway Enrichment Analysis. In vitro and in vivo functional analyses and immunoblotting were performed to verify FGFR4 overexpression consequence. Moreover, the correlation between FGFRs and cancer immune infiltrates was analyzed by TIMER and TCGA databases. And the efficacy of anti-PD-1 mAb treatment was examined in NOG mouse models with overexpressed FGFR1 or FGFR4.

Results

The expression of FGFRs was considerably elevated in STAD than in the normal gastric tissues and was significantly correlated with poor OS and PFS. ROC curve showed the accuracy of the FGFRs in tumor diagnosis, among which FGFR4 had the highest ROC value. Besides, univariate and multivariate analysis revealed that FGFR4 was an independent prognostic factor for GC patients. According to a GO/KEGG analysis, the FGFRs were implicated in the ERK/MAPK, PI3K-AKT and extracellular matrix (ECM) receptor signaling pathways. In vivo and in vitro studies revealed that overexpression of FGFR4 stimulated GC cell proliferation, invasion, and migration. In addition, FGFR1 expression was positively correlated with infiltrating levels of CD8+ T-cells, CD4+ T-cells, macrophages, and dendritic cells in STAD. In contrast, FGFR4 expression was negatively correlated with tumor-infiltrating lymphocytes. Interestingly, overexpression of FGFR1 in the NOG mouse model improved the immunotherapeutic impact of GC, while overexpression of FGFR4 impaired the effect. When combined with an FGFR4 inhibitor, the anti-tumor effect of anti-PD-1 treatment increased significantly in a GC xenograft mouse model with overexpressed FGFR4.

Conclusions

FGFRs has critical function in GC and associated with immune cell infiltration, which might be a potential prognosis biomarker and predictor of response to immunotherapy in GC.

Small Molecule Inhibitors for Hepatocellular Carcinoma: Advances and Challenges

According to data provided by World Health Organization, hepatocellular carcinoma (HCC) is the sixth most common cause of deaths due to cancer worldwide. Tremendous progress has been achieved over the last 10 years developing novel agents for HCC treatment, including small-molecule kinase inhibitors. Several small molecule inhibitors currently form the core of HCC treatment due to their versatility since they would be more easily absorbed and have higher oral bioavailability, thus easier to formulate and administer to patients. In addition, they can be altered structurally to have greater volumes of distribution, allowing them to block extravascular molecular targets and to accumulate in a high concentration in the tumor microenvironment. Moreover, they can be designed to have shortened half-lives to control for immune-related adverse events. Most importantly, they would spare patients, healthcare institutions, and society as a whole from the burden of high drug costs. The present review provides an overview of the pharmaceutical compounds that are licensed for HCC treatment and other emerging compounds that are still investigated in preclinical and clinical trials. These molecules are targeting different molecular targets and pathways that are proven to be involved in the pathogenesis of the disease.

Combination of microtubule targeting agents with other antineoplastics for cancer treatment

Microtubule targeting agents (MTAs) have attracted extensive attention for cancer treatment. However, their clinical efficacies are limited by intolerable toxicities, inadequate efficacy and acquired multidrug resistance. The combination of MTAs with other antineoplastics has become an efficient strategy to lower the toxicities, overcome resistance and improve the efficacies for cancer treatment. In this article, we review the combinations of MTAs with some other anticancer drugs, such as cytotoxic agents, kinases inhibitors, histone deacetylase inhibitors, immune checkpoints inhibitors, to overcome these obstacles. We strongly believe that this review will provide helpful information for combination therapy based on MTAs.

Contribution of machine learning to tumor growth inhibition modeling for hepatocellular carcinoma patients under Roblitinib (FGF401) drug treatment

Machine learning (ML) opens new perspectives in identifying predictive factors of efficacy among a large number of patients’ characteristics in oncology studies. The objective of this work was to combine ML with population pharmacokinetic/pharmacodynamic (PK/PD) modeling of tumor growth inhibition to understand the sources of variability between patients and therefore improve model predictions to support drug development decisions. Data from 127 patients with hepatocellular carcinoma enrolled in a phase I/II study evaluating once‐daily oral doses of the fibroblast growth factor receptor FGFR4 kinase inhibitor, Roblitinib (FGF401), were used. Roblitinib  PKs was best described by a two‐compartment model with a delayed zero‐order absorption and linear elimination. Clinical efficacy using the longitudinal sum of the longest lesion diameter data was described with a population PK/PD model of tumor growth inhibition including resistance to treatment. ML, applying elastic net modeling of time to progression data, was associated with cross‐validation, and allowed to derive a composite predictive risk score from a set of 75 patients’ baseline characteristics. The two approaches were combined by testing the inclusion of the continuous risk score as a covariate on PD model parameters. The score was found as a significant covariate on the resistance parameter and resulted in 19% reduction of its variability, and 32% variability reduction on the average dose for stasis. The final PK/PD model was used to simulate effect of patients’ characteristics on tumor growth inhibition profiles. The proposed methodology can be used to support drug development decisions, especially when large interpatient variability is observed.

A first-in-human phase 1/2 study of FGF401 and combination of FGF401 with spartalizumab in patients with hepatocellular carcinoma or biomarker-selected solid tumors

BACKGROUND

Deregulation of FGF19-FGFR4 signaling is found in several cancers, including hepatocellular carcinoma (HCC), nominating it for therapeutic targeting. FGF401 is a potent, selective FGFR4 inhibitor with antitumor activity in preclinical models. This study was designed to determine the recommended phase 2 dose (RP2D), characterize PK/PD, and evaluate the safety and efficacy of FGF401 alone and combined with the anti-PD-1 antibody, spartalizumab.

METHODS

Patients with HCC or other FGFR4/KLB expressing tumors were enrolled. Dose-escalation was guided by a Bayesian model. Phase 2 dose-expansion enrolled patients with HCC from Asian countries (group1), non-Asian countries (group2), and patients with other solid tumors expressing FGFR4 and KLB (group3). FGF401 and spartalizumab combination was evaluated in patients with HCC.

RESULTS

Seventy-four patients were treated in the phase I with single-agent FGF401 at 50 to 150 mg. FGF401 displayed favorable PK characteristics and no food effect when dosed with low-fat meals. The RP2D was established as 120 mg qd. Six of 70 patients experienced grade 3 dose-limiting toxicities: increase in transaminases (n = 4) or blood bilirubin (n = 2). In phase 2, 30 patients in group 1, 36 in group 2, and 20 in group 3 received FGF401. In total, 8 patients experienced objective responses (1 CR, 7 PR; 4 each in phase I and phase II, respectively). Frequent adverse events (AEs) were diarrhea (73.8%), increased AST (47.5%), and ALT (43.8%). Increase in levels of C4, total bile acid, and circulating FGF19, confirmed effective FGFR4 inhibition. Twelve patients received FGF401 plus spartalizumab. RP2D was established as FGF401 120 mg qd and spartalizumab 300 mg Q3W; 2 patients reported PR.

CONCLUSIONS

At biologically active doses, FGF401 alone or combined with spartalizumab was safe in patients with FGFR4/KLB-positive tumors including HCC. Preliminary clinical efficacy was observed. Further clinical evaluation of FGF401 using a refined biomarker strategy is warranted.

TRIAL REGISTRATION

NCT02325739 .

Regulatory mechanism of miR-20a-5p expression in Cancer

MicroRNAs(miRNAs) are non-coding single-stranded RNA molecules encoded by endogenous genes with a length of about 22 nucleotides. The dysregulation of miRNAs has been proven to be one of the vital causes of cancer, which makes them a biomarker for cancer diagnosis and prognosis. Compared with surgery and chemotherapy, nucleic acid therapy targeting specific miRNAs is a promising candidate for cancer treatment. miR-20a-5p plays an anticancer role in high-incidence human cancers such as cervical cancer, breast cancer and leukemia, which is of great importance in the diagnosis of cancers. The up-regulation and down-regulation of miR-20a-5p offers a possible breakthrough for the treatment of cancers. In this paper, we aim to investigate the functional significance of miR-20a-5p in different cancers, reviewing the expression differences of miR-20a-5p in cancer, while systematically summarizing the changes of circRNA-miR-20a-5p networks, and probe how it promotes messenger RNA (mRNA) degradation or inhibits mRNA translation to regulate downstream gene expression. We've also summarized the biogenesis mechanism of miRNAs, and emphasized its role in cell proliferation, cell apoptosis and cell migration. On this basis, we believe that miR-20a-5p is a promising and effective marker for cancer diagnosis, prognosis and treatment.

6-Amino-2,4,5-trimethylpyridin-3-ol and 2-amino-4,6-dimethylpyrimidin-5-ol derivatives as selective fibroblast growth factor receptor 4 inhibitors: design, synthesis, molecular docking, and anti-hepatocellular carcinoma efficacy evaluation

A novel series of aminotrimethylpyridinol and aminodimethylpyrimidinol derivatives were designed and synthesised for FGFR4 inhibitors. Structure-activity relationship on the FGFR4 inhibitory activity of the new compounds was clearly elucidated by an intensive molecular docking study. Anti-cancer activity of the compounds was evaluated using hepatocellular carcinoma (HCC) cell lines and a chick chorioallantoic membrane (CAM) tumour model. Compound 6O showed FGFR4 inhibitory activity over FGFR1 - 3. Compared to the positive control BLU9931, compound 6O exhibited at least 8 times higher FGFR4 selectivity. Strong anti-proliferative activity of compound 6O was observed against Hep3B, an HCC cell line which was a much more sensitive cell line to BLU9931. In vivo anti-tumour activity of compound 6O against Hep3B-xenografted CAM tumour model was almost similar to BLU9931. Overall, compound 6O, a novel derivative of aminodimethylpyrimidinol, was a selective FGFR4 kinase inhibitor blocking HCC tumour growth.

Structure-based design of a dual-warhead covalent inhibitor of FGFR4

The fibroblast growth factor 19 (FGF19)/fibroblast growth factor receptor 4 (FGFR4) signaling pathways play critical roles in a variety of cancers, such as hepatocellular carcinoma (HCC). FGFR4 is recognized as a promising target to treat HCC. Currently, all FGFR covalent inhibitors target one of the two cysteines (Cys477 and Cys552). Here, we designed and synthesized a dual-warhead covalent FGFR4 inhibitor, CXF-009, targeting Cys477 and Cys552 of FGFR4. We report the cocrystal structure of FGFR4 with CXF-009, which exhibits a dual-warhead covalent binding mode. CXF-009 exhibited stronger selectivity for FGFR4 than FGFR1-3 and other kinases. CXF-009 can also potently inhibit the single cystine mutants, FGFR4(C477A) and FGFR4(C552A), of FGFR4. In summary, our study provides a dual-warhead covalent FGFR4 inhibitor that can covalently target two cysteines of FGFR4. CXF-009, to our knowledge, is the first reported inhibitor that forms dual-warhead covalent bonds with two cysteine residues in FGFR4. CXF-009 also has the potential to overcome drug induced resistant FGFR4 mutations and might serve as a lead compound for future anticancer drug discovery.

Design, Synthesis, and Biological Evaluation of Aminoindazole Derivatives as Highly Selective Covalent Inhibitors of Wild-Type and Gatekeeper Mutant FGFR4

Aberrant FGF19/FGFR4 signaling has been shown to be an oncogenic driver of growth and survival in human hepatocellular carcinoma (HCC) with several pan-FGFR inhibitors and FGFR4-selective inhibitors currently being evaluated in the clinic. However, FGFR4 gatekeeper mutation induced acquired resistance remains an unmet clinical challenge for HCC treatment. Thus, a series of aminoindazole derivatives were designed and synthesized as new irreversible inhibitors of wild-type and gatekeeper mutant FGFR4. One representative compound (7v) exhibited excellent potency against FGFR4, FGFR4^V550L, and FGFR4^V550M with nanomolar activity in both the biochemical and cellular assays while sparing FGFR1/2/3. While compound 7v demonstrated modest in vivo antitumor efficacy in nude mice bearing the Huh-7 xenograft model consistent with its unfavorable pharmacokinetic properties, it provides a promising new starting point for future drug discovery combating FGFR4 gatekeeper mediated resistance in HCC patients.

Development of the First Covalent Monopolar Spindle Kinase 1 (MPS1/TTK) Inhibitor

Monopolar spindle kinase 1 (MPS1/TTK) is a key element of the mitotic checkpoint and clinically evaluated as a target in the treatment of aggressive tumors such as triple-negative breast cancer. While long drug-target residence times have been suggested to be beneficial in the context of therapeutic MPS1 inhibition, no irreversible inhibitors have been reported. Here we present the design and characterization of the first irreversible covalent MPS1 inhibitor, RMS-07, targeting a poorly conserved cysteine in the kinase's hinge region. RMS-07 shows potent MPS1 inhibitory activity and selectivity against all protein kinases with an equivalent cysteine but also in a broader kinase panel. We demonstrate potent cellular target engagement and pronounced activity against various cancer cell lines. The covalent binding mode was validated by mass spectrometry and an X-ray crystal structure. This proof of MPS1 covalent ligandability may open new avenues for the design of MPS1-specific chemical probes or drugs.

BCL-XL inhibition induces an FGFR4-mediated rescue response in colorectal cancer

The heterogeneous therapy response observed in colorectal cancer is in part due to cancer stem cells (CSCs) that resist chemotherapeutic insults. The anti-apoptotic protein BCL-XL plays a critical role in protecting CSCs from cell death, where its inhibition with high doses of BH3 mimetics can induce apoptosis. Here, we screen a compound library for synergy with low-dose BCL-XL inhibitor A-1155463 to identify pathways that regulate sensitivity to BCL-XL inhibition and reveal that fibroblast growth factor receptor (FGFR)4 inhibition effectively sensitizes to A-1155463 both in vitro and in vivo. Mechanistically, we identify a rescue response that is activated upon BCL-XL inhibition and leads to rapid FGF2 secretion and subsequent FGFR4-mediated post-translational stabilization of MCL-1. FGFR4 inhibition prevents MCL-1 upregulation and thereby sensitizes CSCs to BCL-XL inhibition. Altogether, our findings suggest a cell transferable induction of a FGF2/FGFR4 rescue response in CRC that is induced upon BCL-XL inhibition and leads to MCL-1 upregulation.

Novel Bile Acid-Dependent Mechanisms of Hepatotoxicity Associated with Tyrosine Kinase Inhibitors

Drug-induced liver injury (DILI) is the leading cause of acute liver failure and a major concern in drug development. Altered bile acid homeostasis via inhibition of the bile salt export pump (BSEP) is one mechanism of DILI. Dasatinib, pazopanib, and sorafenib are tyrosine kinase inhibitors (TKIs) that competitively inhibit BSEP and increase serum biomarkers for hepatotoxicity in ∼25-50% of patients. However, the mechanism(s) of hepatotoxicity beyond competitive inhibition of BSEP are poorly understood. This study examined mechanisms of TKI-mediated hepatotoxicity associated with altered bile acid homeostasis. Dasatinib, pazopanib, and sorafenib showed bile acid-dependent toxicity at clinically relevant concentrations, based on the C-DILI assay using sandwich-cultured human hepatocytes (SCHH). Among several bile acid-relevant genes, cytochrome P450 (CYP) 7A1 mRNA was specifically upregulated by 6.2- to 7.8-fold (dasatinib) and 5.7- to 9.3-fold (pazopanib), compared with control, within 8 hours. This was consistent with increased total bile acid concentrations in culture medium up to 2.3-fold, and in SCHH up to 1.4-fold, compared with control, within 24 hours. Additionally, protein abundance of sodium taurocholate co-transporting polypeptide (NTCP) was increased up to 2.0-fold by these three TKIs. The increase in NTCP protein abundance correlated with increased function; dasatinib and pazopanib increased hepatocyte uptake clearance (CL_uptake) of taurocholic acid, a probe bile acid substrate, up to 1.4-fold. In conclusion, upregulation of CYP7A1 and NTCP in SCHH constitute novel mechanisms of TKI-associated hepatotoxicity. SIGNIFICANCE STATEMENT: Understanding the mechanisms of hepatotoxicity associated with tyrosine kinase inhibitors (TKIs) is fundamental to development of effective and safe intervention therapies for various cancers. Data generated in sandwich-cultured human hepatocytes, an in vitro model of drug-induced hepatotoxicity, revealed that TKIs upregulate bile acid synthesis and alter bile acid uptake and excretion. These findings provide novel insights into additional mechanisms of bile acid-mediated drug-induced liver injury, an adverse effect that limits the use and effectiveness of TKI treatment in some cancer patients.

FGFR4 inhibitors for the treatment of hepatocellular carcinoma: a synopsis of therapeutic potential

INTRODUCTION

The mainstay pharmacological approaches to patients with hepatocellular carcinoma (HCC) are tyrosine kinase inhibitors, antiangiogenic agents, and immune checkpoint inhibitors in combination therapy. Aberrant signaling of fibroblast growth factor 19 (FGF19) and its corresponding receptor, fibroblast growth factor receptor 4 (FGFR4), are a driver of HCC cell growth and survival. However, the clinical potential of agents targeting aberrant FGF19/FGFR4 signaling has not been adequately explored.

AREAS COVERED

We evaluate the existing literature on aberrant signaling of FGF19/FGFR4 in HCC and address the recent preclinical and clinical advances of selective FGFR4 inhibitors in the treatment of advanced HCC. Our literature search was performed in September 2021 on clinical trials and ongoing studies published in journals or presented in conferences for cancer research.

EXPERT OPINION

Preclinical studies show selective FGFR4 inhibitors to be highly potent. These inhibitors also show promise in clinical trials and demonstrate manageable on-target side effects. An emphasis should be placed on the development of predictive biomarkers and on enhancing the understanding of primary and acquired resistance mechanisms. This will inspire rationale combination therapy strategies for testing in future clinical trials.

Anti-cancer effects of 3,4-dihydropyrimido[4,5-d]pyrimidin-2(1H)-one derivatives on hepatocellular carcinoma harboring FGFR4 activation

Hepatocellular carcinoma (HCC) is disease with a high mortality rate and limited treatment options. Alterations of fibroblast growth factor receptor 4 (FGFR4) has been regarded as an oncogenic driver for HCC and a promising target for HCC therapeutics. Herein, we report that GNF-7, a multi-targeted kinase inhibitor, and its derivatives including SIJ1263 (IC₅₀ < 1 nM against FGFR4) are highly potent FGFR4 inhibitors and are capable of strongly suppressing proliferation of HCC cells and Ba/F3 cells transformed with wtFGFR4 or mtFGFR4. Compared with known FGFR4 inhibitors, both GNF-7 and SIJ1263 possess much higher (up to 100-fold) anti-proliferative activities via FGFR signaling blockade and apoptosis on HCC cells. Especially, SIJ1263 is 80-fold more potent (GI₅₀ = 24 nM) on TEL-FGFR4 V550E Ba/F3 cells than BLU9931, which suggests that SIJ1263 would be effective for overriding drug resistance. In addition, both substances strongly suppress migration/invasion and colony formation of HCC cells. It is worth noting that SIJ1263 is superior to GNF-7 with regards to the fact that activities of SIJ1263 are higher than those of GNF-7 in all assays performed in this study. Collectively, this study provides insight into designing highly potent FGFR4 inhibitors capable of potentially overcoming drug-resistance for the treatment of HCC patients.

Dark and bright side of targeting fibroblast growth factor receptor 4 in the liver

Fibroblast growth factor (FGF) receptor 4 (FGFR4) and its cognate ligand, FGF19, are implicated in a range of cellular processes, including differentiation, metabolism and proliferation. Indeed, their aberrant activation has been associated with the development of hepatic tumours. Despite great advances in early diagnosis and the development of new therapies, liver cancer is still associated with a high mortality rate, owing primarily to high molecular heterogeneity and unclear molecular targeting. The development of FGFR4 inhibitors is a promising tool in patients with concomitant supraphysiological levels of FGF19 and several clinical trials are testing these treatments for patients with advanced hepatocellular carcinoma (HCC). Conversely, using FGF19 analogues to activate FGFR4-KLOTHO β represents a novel therapeutic strategy in patients presenting with cholestatic liver disorders and non-alcoholic steatohepatitis, which could potentially prevent the development of metabolic HCC. Herein, we provide an overview of the currently available therapeutic options for targeting FGFR4 in HCC and other liver diseases, highlighting the need to carefully stratify patients and personalise therapeutic strategies.

The FGFR Family Inhibitor AZD4547 Exerts an Antitumor Effect in Ovarian Cancer Cells

The dysregulation of fibroblast growth factor (FGF) signaling has been implicated in tumorigenesis, tumor progression, angiogenesis, and chemoresistance. The small-molecule AZD4547 is a potent inhibitor of FGF receptors. This study was performed to investigate the antitumor effects and determine the mechanistic details of AZD4547 in ovarian cancer cells. AZD4547 markedly inhibited the proliferation and increased the apoptosis of ovarian cancer cells. AZD4547 also suppressed the migration and invasion of ovarian cancer cells under nontoxic conditions. Furthermore, it attenuated the formation of spheroids and the self-renewal capacities of ovarian cancer stem cells and exerted an antiangiogenic effect. It also suppressed in vivo tumor growth in mice. Collectively, this study demonstrated the antitumor effect of AZD4547 in ovarian cancer cells and suggests that it is a promising agent for ovarian cancer therapy.

Therapeutically Targeting Cancers That Overexpress FOXC1: A Transcriptional Driver of Cell Plasticity, Partial EMT, and Cancer Metastasis

Metastasis accounts for more than 90% of cancer related mortality, thus the most pressing need in the field of oncology today is the ability to accurately predict future onset of metastatic disease, ideally at the time of initial diagnosis. As opposed to current practice, what would be desirable is that prognostic, biomarker-based detection of metastatic propensity and heightened risk of cancer recurrence be performed long before overt metastasis has set in. Without such timely information it will be impossible to formulate a rational therapeutic treatment plan to favorably alter the trajectory of disease progression. In order to help inform rational selection of targeted therapeutics, any recurrence/metastasis risk prediction strategy must occur with the paired identification of novel prognostic biomarkers and their underlying molecular regulatory mechanisms that help drive cancer recurrence/metastasis (i.e. recurrence biomarkers). Traditional clinical factors alone (such as TNM staging criteria) are no longer adequately prognostic for this purpose in the current molecular era. FOXC1 is a pivotal transcription factor that has been functionally implicated to drive cancer metastasis and has been demonstrated to be an independent predictor of heightened metastatic risk, at the time of initial diagnosis. In this review, we present our viewpoints on the master regulatory role that FOXC1 plays in mediating cancer stem cell traits that include cellular plasticity, partial EMT, treatment resistance, cancer invasion and cancer migration during cancer progression and metastasis. We also highlight potential therapeutic strategies to target cancers that are, or have evolved to become, “transcriptionally addicted” to FOXC1. The potential role of FOXC1 expression status in predicting the efficacy of these identified therapeutic approaches merits evaluation in clinical trials.

Hepatocellular carcinoma (HCC): the most promising therapeutic targets in the preclinical arena based on tumor biology characteristics

INTRODUCTION

: Hepatocellular carcinoma (HCC) is a malignant liver tumor characterized by high molecular heterogeneity, which has hampered the development of effective targeted therapies severely. Recent experimental data have unraveled novel promising targets for HCC treatment.

AREAS COVERED

: Eligible articles were retrieved from PubMed and Web of Science databases up to July 2021. This review summarizes the established targeted therapies for advanced HCC, focusing on the strategies to overcome drug resistance and the search for combinational treatments. In addition, conventional biomarkers holding the promises for HCC treatments and novel therapeutic targets from the research field are discussed.

EXPERT OPINION

: HCC is a molecularly complex disease, with several and distinct pathways playing critical roles in different tumor subtypes. Experimental models recapitulating the features of each tumor subset would be highly beneficial to design novel and more effective therapies against this disease. Furthermore, a deeper understanding of combinatorial drug synergism and the role of the tumor microenvironment in HCC will lead to improved therapeutic outcomes.

Targeted inhibition of FGF19/FGFR cascade improves antitumor immunity and response rate in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common liver cancer globally, claiming nearly 1 million lives each year. The overexpression of fibroblast growth factor (FGF) receptors (FGFRs) signaling cascade has been shown to contribute to tumorigenesis, metastasis, and poor prognosis in HCC. Therefore, targeted inhibition of the FGF/FGFR cascade may represent a new treatment strategy for HCC patients.

METHODS

HCC patient-derived xenograft (PDX) models were implanted into either severe combined immunodeficient (SCID) or CD34+hu-NSG (humanized) mice and subsequently treated with vehicle, infigratinib (FGFR1-3 inhibitor), FGF401 (FGFR4 inhibitor), or the combination of infigratinib and FGF401. Tumor progressions, overall survival of mice, lung metastasis, and drug resistance were monitored, and samples collected at the end of the treatment cycle were subjected to Western blot analyses and immunohistochemistry.

RESULTS

HCC PDX models expressing high levels of FGF19/FGFR4 or FGFR2/3 showed favorable initial treatment response to FGF401 and infigratinib, respectively. However, progressive disease due to acquired resistance was observed. Combination infigratinib/FGF401 augmented the antitumor activity, response rate, and overall survival of mice. This combination significantly increased the infiltration of B cells, macrophages, CD8+ T cells, and CD4+ T cells associated with granzyme-B-mediated apoptosis, delayed onset of resistance, and inhibited metastasis by potently inhibiting several critical signaling pathways involved in proliferation and metastasis.

CONCLUSIONS

Our findings suggest that HCC patients with high FGFR2/3 or FGF19/FGFR4 expressing tumors might benefit from a combination infigratinib/FGF401; thus, supporting its evaluation in clinical trials.

Novel Regulatory Factors and Small-Molecule Inhibitors of FGFR4 in Cancer

Fibroblast growth factor receptor 4 (FGFR4) is a tyrosine kinase receptor that is a member of the fibroblast growth factor receptor family and is stimulated by highly regulated ligand binding. Excessive expression of the receptor and its ligand, especially FGF19, occurs in many types of cancer. Abnormal FGFR4 production explains these cancer formations, and therefore, this receptor has emerged as a potential target for inhibiting cancer development. This review discusses the diverse mechanisms of oncogenic activation of FGFR4 and highlights some currently available inhibitors targeting FGFR4.

Advances of Fibroblast Growth Factor/Receptor Signaling Pathway in Hepatocellular Carcinoma and its Pharmacotherapeutic Targets

Hepatocellular carcinoma (HCC) is a type of primary liver cancer with poor prognosis, and its incidence and mortality rate are increasing worldwide. It is refractory to conventional chemotherapy and radiotherapy owing to its high tumor heterogeneity. Accumulated genetic alterations and aberrant cell signaling pathway have been characterized in HCC. The fibroblast growth factor (FGF) family and their receptors (FGFRs) are involved in diverse biological activities, including embryonic development, proliferation, differentiation, survival, angiogenesis, and migration, etc. Data mining results of The Cancer Genome Atlas demonstrate high levels of FGF and/or FGFR expression in HCC tumors compared with normal tissues. Moreover, substantial evidence indicates that the FGF/FGFR signaling axis plays an important role in various mechanisms that contribute to HCC development. At present, several inhibitors targeting FGF/FGFR, such as multikinase inhibitors, specific FGFR4 inhibitors, and FGF ligand traps, exhibit antitumor activity in preclinical or early development phases in HCC. In this review, we summarize the research progress regarding the molecular implications of FGF/FGFR-mediated signaling and the development of FGFR-targeted therapeutics in hepatocarcinogenesis.

Src is essential for the endosomal delivery of the FGFR4 signaling complex in hepatocellular carcinoma

Background

Hepatocytes usually express fibroblast growth factor receptor 4 (FGFR4), but not its ligand, fibroblast growth factor 19 (FGF19). A subtype of hepatocellular carcinoma (HCC) expresses FGF19, which activates the FGFR4 signaling pathway that induces cell proliferation. FGFR4 inhibitors that target this mechanism are under clinical development for the treatment of HCCs with FGF19 amplification or FGFR4 overexpression. Src plays an essential role in the FGFR1 and FGFR2 signaling pathways. However, it is yet to be understood whether Src has any role in the FGF19-FGFR4 pathway in HCCs. In this study, we aimed to elucidate the role of Src in the FGF19-FGFR4 axis in HCC.

Methods

3 HCC cell lines expressing both FGF19 and FGFR4 were selected. The expression of each protein was suppressed by siRNA treatment, and the activity-regulating relationship between FGFR4 and Src was investigated by westernblot. Co-immunoprecipitation was performed using the FGFR4 antibody to identify the endosomal complex formation and receptor endocytosis. The intracellular migration pathways of the endosomal complex were observed by immuno-fluorescence and nuclear co-immunoprecipitation. Dasatinib and BLU9931 were used for cytotoxicity comparison.

Results

FGFR4 modulates the activity of Src and Src modulates the expression of FGFR4, showing a mutual regulatory relationship. FGFR4 activated by FGF19 formed an endosomal complex with Src and STAT3 and moved to the nucleus. However, when Src was suppressed, the formation of the endosomal complex was not observed. FGFR4 was released from the complex transferred into the nucleus and the binding of Src and STAT3 was maintained. Dasatinib showed cytotoxic results comparable to BLU9931. The results of our study demonstrated that Src is essential for the nuclear transport of STAT3, as it induces the endosomal delivery of FGFR4 in FGF19-expressing HCC cell lines.

Conclusions

We found that Src is essential for the endosomal delivery of the FGFR4 signaling complex in HCC. Our findings provide a scientific rationale for repurposing Src inhibitors for the treatment of HCCs in which the FGFR4 pathway is activated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02807-4.

FGFR3 phosphorylates EGFR to promote cisplatin-resistance in ovarian cancer

Ovarian cancer is a deadly gynecologic cancer, and the majority of patients with ovarian cancer experience relapse after traditional treatment. Cisplatin (DDP) is a common chemotherapeutic drug for ovarian cancer, but many patients acquire DDP-resistance after treatment with long-term chemotherapy. The mechanisms of drug-resistance in ovarian cancer are not clear, and we thus aim to investigate novel targets for DDP-resistant ovarian cancer. Differential analysis, KEGG pathway enrichment and protein interaction networks were employed to identify the key genes related to DDP-resistance in ovarian cancer. Subsequently, cell viability, apoptosis and migration were measured to assess the effect of fibroblast growth factor receptor 3 (FGFR3) on DDP-resistance. Further, Pearson correlation analysis and co-expression analysis were used to explore the downstream pathways of FGFR3, and the function of FGFR3 and its downstream targets were further demonstrated by in vitro and nude mice experiments. FGFR3 were expressed at high levels in DDP-resistant ovarian cancer cells. FGFR3 silencing suppressed the activation of PI3K/AKT pathway and impeded the drug-resistance and development of tumor cells. Afterwards, we found that FGFR3 was co-expressed with epidermal growth factor receptor (EGFR). FGFR3 overexpression elevated EGFR phosphorylation and activated PI3K/AKT signaling. Furthermore, in nude mice, silencing FGFR3 and inhibiting EGFR phosphorylation were observed to promote the therapeutic effect of DDP. In conclusion, FGFR3 overexpression enhances DDP-resistance of ovarian cancer by promoting EGFR phosphorylation and further activating PI3K/AKT pathway. This study may offer promising targets for DDP-resistant ovarian cancer.

FGF/FGFR Signaling in Hepatocellular Carcinoma: From Carcinogenesis to Recent Therapeutic Intervention

Simple Summary

As the most common primary liver cancer, HCC is a tricky cancer resistant to systemic therapies. The fibroblast growth factor family and its receptors are gaining more and more attention in various cancers. Noticing an explosion in the number of studies about aberrant FGF/FGFR signaling in HCC being studied, we were encouraged to summarize them. This review discusses how FGF/FGFR signaling influences HCC development and its implications in HCC prediction and target treatment, and combination treatment.

Abstract

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, ranking third in cancer deaths worldwide. Over the last decade, several studies have emphasized the development of tyrosine kinase inhibitors (TKIs) to target the aberrant pathways in HCC. However, the outcomes are far from satisfactory due to the increasing resistance and adverse effects. The family of fibroblast growth factor (FGF) and its receptors (FGFR) are involved in various biological processes, including embryogenesis, morphogenesis, wound repair, and cell growth. The aberrant FGF/FGFR signaling is also observed in multiple cancers, including HCC. Anti-FGF/FGFR provides delightful benefits for cancer patients, especially those with FGF signaling alteration. More and more multi-kinase inhibitors targeting FGF signaling, pan-FGFR inhibitors, and selective FGFR inhibitors are now under preclinical and clinical investigation. This review summarizes the aberrant FGF/FGFR signaling in HCC initiating, development and treatment status, and provide new insights into the treatment of HCC.

Triglycerides in Nonalcoholic Fatty Liver Disease: Guilty Until Proven Innocent

End-stage liver disease (ESLD) is a rare but often fatal complication of nonalcoholic fatty liver disease (NAFLD). In NAFLD, insulin resistance, which is clinically defined as the impairment of insulin's ability to maintain glucose homeostasis, is associated with perturbations in insulin action that promote triglyceride accumulation, such as increasing de novo lipogenesis. However, the key step in the development of ESLD is not the accumulation of triglycerides, but hepatocyte injury. Whether and how triglycerides promote hepatocyte injury remains unclear. Consequently, it is difficult to predict whether drugs designed to reduce hepatic triglycerides will prevent the most important complications of NAFLD.