Fibroblast Growth Factor Receptor Kinase Research Articles

FGFR2-fusions define a clinically actionable molecular subset of pancreatic cancer

Genomic alterations in fibroblast growth factor receptor (FGFR) genes are present in a small number of metastatic pancreatic ductal adenocarcinomas (PDAC) and may represent an emerging subgroup of patients likely to benefit from FGFR targeted therapies. Here we present four FGFR2 fusion-positive metastatic PDAC patients who exhibited durable responses or disease control to FGFR kinase inhibitors. Utilizing our custom FGFR focused cell-free DNA assay, FGFR-Dx, we serially monitored variant allele fractions of FGFR2 fusions during FGFR inhibitor treatment and observed dynamic changes correlating with clinical responses. Genomic analysis of 30,229 comprehensively profiled pancreatic cancers revealed FGFR1-3 fusions in 245 cases, an incidence of 0.81%. FGFR fusions were generally mutually exclusive from other known oncogenes. Our findings provide clinical evidence for identifying and treating FGFR2 fusion-positive PDAC patients with FGFR targeted therapy.

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.

Pharmacological characteristics and clinical effectiveness of Futibatinib (Lytgobi® Tablets), a covalently-binding, irreversible FGFR1-4 inhibitor

Futibatinib (Lytgobi® Tablets 4 ‍mg), a novel fibroblast growth factor receptor (FGFR) inhibitor developed by Taiho Pharmaceutical using the Cysteinomix Drug Discovery Platform, was approved in Japan in June 2023 for the treatment of patients with unresectable biliary tract cancer with FGFR2 fusion or rearrangement that had progressed after at least one prior chemotherapy. Futibatinib covalently binds to the cysteine residue in the FGFR kinase domain P-loop structure and is believed to exert antitumor activity by selectively and irreversibly inhibiting FGFR1-4. Many FGFR inhibitors under development are ATP-competitive; however, futibatinib is the first approved covalently-binding irreversible FGFR inhibitor. It inhibits cell proliferation by inhibiting FGFR phosphorylation and its downstream signaling pathways in cancer cell lines. Futibatinib showed inhibitory activity against a wider range of FGFR mutants than ATP-competitive, reversible FGFR inhibitors and inhibited cell proliferation without significantly deviating from the inhibitory effect on wild-type FGFR. Futibatinib showed antitumor efficacy in mice subcutaneously transplanted with human tumor cell lines driven by FGFR. The international phase 2 study (TAS-120-101) was conducted in patients with refractory intrahepatic cholangiocarcinoma with FGFR2 fusion or rearrangement. The overall response rate was 41.7%, showing consistent efficacy regardless of co-occurring genomic alterations. Although some typical FGFR inhibitor-related side effects were observed, they were manageable and futibatinib had a good safety profile. Futibatinib is an important drug for biliary tract cancer, which has limited treatment options; its development is underway for other types of cancer, and it is expected to benefit more patients.

Ex Vivo Drug Sensitivity Evaluation of a ZMYM2::FGFR1 Fusion-Positive 8p11 Myeloproliferative Syndrome (EMS) Leukemia

Introduction : Fibroblast growth factor receptors (FGFRs) are conserved single transmembrane receptor tyrosine kinases (RTKs) with an extracellular ligand-binding domain and a cytoplasmic tyrosine kinase domain. They play vital roles in cellular proliferation, survival, development, fetal organogenesis, metabolism, and tissue repair. 8p11 myeloproliferative syndrome (EMS) is a hematologic malignancy caused by a translocation of the fibroblast growth factor receptor 1 (FGFR1) gene on chromosome 8p11-12. The most common fusion partner of FGFR1 is the zinc-finger domain ZNF198 (also known as ZMYM2) on chromosome 13q12. Pemigatinib is approved for FGFR fusion positive myeloid/lymphoid neoplasms (MLNs), and other FGFR inhibitors are being tested in clinical trials. However, EMS patients still face a poor prognosis and drug resistance, necessitating further research to overcome these challenges. This study evaluated ex vivo drug screening assay data generated from ZMYM2::FGFR1 positive primary leukemia samples throughout the course of an EMS patient's clinical response and validated these findings on a ZMYM2::FGFR1 positive cell line. Methods : Ex vivo and drug screening experiments were performed on freshly isolated primary patient samples and a ZMYM2::FGFR1-expressing cell line. The fusion was confirmed using FISH, and additional clinical specimens were collected with informed patient consent. Ex vivo drug sensitivity assays were conducted on patient mononuclear cells isolated from blood and bone marrow. IL-3 dependent BaF3 cells were infected with retrovirus containing a ZMYM2::FGFR1-V5 construct. ZMYM2::FGFR1 transformed BaF3 cells were evaluated with single agent and drug combination panels. Sanger sequencing of the FGFR portion of the fusion was performed on patient samples to confirm the breakpoint and identify potential mutations affecting sensitivity to Ponatinib throughout the course of treatment. Results : Sample were obtained with informed consent from a 36-year-old man diagnosed with 8p11 myeloproliferative syndrome and a ZMYM2::FGFR1 fusion along with a RUNX1 R201Q mutation. Ex vivo drug screens performed on isolated mononuclear cells demonstrated sensitivity to Ponatinib and Pemigatinib. He underwent treatment with HyperCVAD plus Ponatinib and subsequently HyperCVAD with Ponatinib and Velcade (Bortezomib) to CR1, FISH for FGFR1 rearrangement was undetected. He was scheduled to proceed with hematopoietic stem cell transplant (HSCT), however his pre-transplant bone marrow biopsy showed return of his FGFR1 translocation by FISH. Ex vivo drug screening assays confirmed resistance to Ponatinib, but continued sensitivity to Pemigatinib. He was transitioned to treatment with single agent Pemigatinib and was able to re-clear his FGFR1 fusion by FISH, and has since undergone hematopoietic stem cell transplantation. He remains in remission on post-transplant Pemigatinib maintenance therapy. Sanger sequencing performed at the time of progression on Ponatinib identified a nucleotide alteration resulting in an amino acid substitution (FGFR1 F686L; ZMYM2::FGFR1 F1171L) within the kinase domain that could contribute to decreased Ponatinib sensitivity. Bortezomib and Axitinib exhibited high efficacy on the patient's sample. Ex vivo drug assays performed on ZMYM2::FGFR1 transformed BaF3 cells confirmed the efficacy of Pemigatinib and Ponatinib. Other FGFR inhibitors, including Olverematinib, AZD4547, Axitinib, Cediranib, Dovitinib, and Lenvatinib, also demonstrated exquisite sensitivity. Despite extensive screening, no other single agents or drug combinations exhibited increased effectiveness in the ZMYM2::FGFR1 transformed BaF3 cells except for Trametinib, a MEK inhibitor, and the combination of Belvarafenib (RAF inhibitor) and Gilteritinib (FLT3 inhibitor). Conclusions : Ex vivo drug sensitivity assays demonstrated the highly selective efficacy of FGFR inhibitors in ZMYM2::FGFR1 fusion-positive leukemia cells and a fusion-expressing BaF3 cell line. Mutations in the FGFR1 kinase domain (ZMYM2::FGFR1 F1171L) could contribute to Ponatinib insensitivity. These ex vivo drug screening results provide further support for ongoing clinical trials which are investigating the use of single agent Pemigatinib and other FGFR1 inhibitors for the treatment of patients with FGFR1-fusion positive leukemias.

Preclinical development of a chimeric antigen receptor T cell therapy targeting FGFR4 in rhabdomyosarcoma

Pediatric patients with relapsed or refractory rhabdomyosarcoma (RMS) have dismal cure rates, and effective therapy is urgently needed. The oncogenic receptor tyrosine kinase fibroblast growth factor receptor 4 (FGFR4) is highly expressed in RMS and lowly expressed in healthy tissues. Here, we describe a second-generation FGFR4-targeting chimeric antigen receptor (CAR), based on an anti-human FGFR4-specific murine monoclonal antibody 3A11, as an adoptive Tcell treatment for RMS. The 3A11 CAR Tcells induced robust cytokine production and cytotoxicity against RMS cell lines invitro. In contrast, a panel of healthy human primary cells failed to activate 3A11 CAR Tcells, confirming the selectivity of 3A11 CAR Tcells against tumors with high FGFR4 expression. Finally, we demonstrate that 3A11 CAR Tcells are persistent invivo and can effectively eliminate RMS tumors in two metastatic and two orthotopic models. Therefore, our study credentials CAR Tcell therapy targeting FGFR4 to treat patients with RMS.

N-glycosylation acts as a switch for FGFR1 trafficking between the plasma membrane and nuclear envelope

Fibroblast growth factor receptor 1 (FGFR1) is a heavily N-glycosylated cell surface receptor tyrosine kinase that transmits signals across the plasma membrane, in response to fibroblast growth factors (FGFs). Balanced FGF/FGFR1 signaling is crucial for the development and homeostasis of the human body, and aberrant FGFR1 is frequently observed in various cancers. In addition to its predominant localization to the plasma membrane, FGFR1 has also been detected inside cells, mainly in the nuclear lumen, where it modulates gene expression. However, the exact mechanism of FGFR1 nuclear transport is still unknown. In this study, we generated a glycosylation-free mutant of FGFR1, FGFR1.GF, and demonstrated that it is localized primarily to the nuclear envelope. We show that reintroducing N-glycans into the D3 domain cannot redirect FGFR1 to the plasma membrane or exclude the receptor from the nuclear envelope. Reestablishment of D2 domain N-glycans largely inhibits FGFR1 accumulation in the nuclear envelope, but the receptor continues to accumulate inside the cell, mainly in the ER. Only the simultaneous presence of N-glycans of the D2 and D3 domains of FGFR1 promotes efficient transport of FGFR1 to the plasma membrane. We demonstrate that while disturbed FGFR1 folding results in partial FGFR1 accumulation in the ER, impaired FGFR1 secretion drives FGFR1 trafficking to the nuclear envelope. Intracellular FGFR1.GF displays a high level of autoactivation, suggesting the presence of nuclear FGFR1 signaling, which is independent of FGF. Using mass spectrometry and proximity ligation assay, we identified novel binding partners of the nuclear envelope-localized FGFR1, providing insights into its cellular functions. Collectively, our data define N-glycosylation of FGFR1 as an important regulator of FGFR1 kinase activity and, most importantly, as a switchable signal for FGFR1 trafficking between the nuclear envelope and plasma membrane, which, due to spatial restrictions, shapes FGFR1 interactome and cellular function.EsPakJEGK2gtBioMMpFVm_Video

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

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

Futibatinib (Lytgobi®)

Futibatinib (Lytgobi®)

Molecular dynamics simulations reveal phosphorylation-induced conformational dynamics of the fibroblast growth factor receptor 1 kinase

The Fibroblast Growth Factor Receptor1 (FGFR1) kinase wields exquisite control on cell fate, proliferation, differentiation, and homeostasis. An imbalance of FGFR1 signaling leads to several pathogeneses of diseases ranging from multiple cancers to allergic and neurodegenerative disorders. In this study, we investigated the phosphorylation-induced conformational dynamics of FGFR1 in apo and ATP-bound states via all-atom molecular dynamics simulations. All simulations were performed for 2 × 2 µs. We have also investigated the energetics of the binding of ATP to FGFR1 using the molecular mechanics Poisson-Boltzmann scheme. Our study reveals that the FGFR1 kinase can reach a fully active configuration through phosphorylation and ATP binding. A 3–10 helix formation in the activation loop signifies its rearrangement leading to stability upon ATP binding. The interaction of phosphorylated tyrosine (pTyr654) with positively charged residues forms strong salt-bridge interactions, driving the compactness of the structure. The dynamic cross-correlation map reveals phosphorylation enhances correlated motions and reduces anti-correlated motions between different domains. We believe that the mechanistic understanding of large-conformational changes upon the activation of the FGFR1 kinase will aid the development of novel targeted therapeutics. Communicated by Ramaswamy H. Sarma

Discovery of Futibatinib: The First Covalent FGFR Kinase Inhibitor in Clinical Use.

Deregulating fibroblast growth factor receptor (FGFR) signaling is a promising strategy for cancer therapy. Herein, we report the discovery of compound 5 (TAS-120, futibatinib), a potent and selective covalent inhibitor of FGFR1-4, starting from a unique dual inhibitor of mutant epidermal growth factor receptor and FGFR (compound 1). Compound 5 inhibited all four families of FGFRs in the single-digit nanomolar range and showed high selectivity for over 387 kinases. Binding site analysis revealed that compound 5 covalently bound to the cysteine 491 highly flexible glycine-rich loop region of the FGFR2 adenosine triphosphate pocket. Futibatinib is currently in Phase I-III trials for patients with oncogenically driven FGFR genomic aberrations. In September 2022, the U.S. Food & Drug Administration granted accelerated approval for futibatinib in the treatment of previously treated, unresectable, locally advanced, or metastatic intrahepatic cholangiocarcinoma harboring an FGFR2 gene fusion or other rearrangement.

Metabolic Activation of the Acrylamide Michael Acceptor Warhead in Futibatinib to an Epoxide Intermediate Engenders Covalent Inactivation of CYP3A.

Futibatinib (FUT) is a potent inhibitor of fibroblast growth factor receptor (FGFR) 1-4 that is currently under clinical investigation for intrahepatic cholangiocarcinoma. Unlike its predecessors, FUT possesses an acrylamide warhead, which enables it to bind covalently to a free cysteine residue in the FGFR kinase domain. However, it remains uninterrogated if this electrophilic α, β -unsaturated carbonyl scaffold could also directly or indirectly engender off-target covalent binding to nucleophilic centers on other cellular proteins. Here, we discovered that FUT inactivated both CYP3A isoforms with inactivator concentration at half-maximum inactivation rate constant, maximum inactivation rate constant, and partition ratios of 12.5 and 51.4 µ M, 0.25 and 0.06 minutes-1, and ∼52 and ∼58 for CYP3A4 and CYP3A5, respectively. Along with its time-, concentration-, and cofactor-dependent inhibitory profiles, FUT also exhibited several cardinal features that were consistent with mechanism-based inactivation. Moreover, the nature of inactivation was unlikely to be pseudo-irreversible and instead arose from the covalent modification of the cytochrome P450 apoprotein and/or its heme moiety due to the lack of substantial enzyme activity recovery following dialysis and chemical oxidation, as well as the absence of the diagnostic Soret peak in spectral analyses. Finally, utilizing glutathione (GSH) trapping and high-resolution mass spectrometry, we illuminated that while the acrylamide moiety in FUT could nonenzymatically conjugate to GSH via Michael addition, it was not implicated in the covalent inactivation of CYP3A. Rather, we surmised that it likely stemmed from the metabolic activation of its acrylamide covalent warhead to a highly electrophilic epoxide intermediate that could covalently modify CYP3A and culminate in its catalytic inactivation. SIGNIFICANCE STATEMENT: In this study, we reported for the first time the inactivation of CYP3A by futibatinib (FUT). Furthermore, using FUT as an exemplary targeted covalent inhibitor, our study revealed the propensity for its acrylamide Michael acceptor moiety to be metabolically activated to a highly electrophilic epoxide. Due to the growing resurgence of covalent inhibitors and the well-established toxicological ramifications associated with epoxides, we advocate that closer scrutiny be adopted when profiling the reactive metabolites of compounds possessing an α, β -unsaturated carbonyl scaffold.

Circular RNA circVAMP3 promotes aerobic glycolysis and proliferation by regulating LDHA in renal cell carcinoma

Metabolic dysfunction is seen in cancer cells where increased glycolysis provides energy for growth. Circular RNAs (circRNAs) are thought to assist in glucose metabolism and the switch to glycolysis. Through screening, we found that circVAMP3 was necessary for both glycolytic and proliferative activities in renal cell carcinoma (RCC). Furthermore, circVAMP3 expression was elevated in RCC patients in correspondence with TNM stage. Mechanistically, circVAMP3 was observed to interact directly with lactate dehydrogenase A (LDHA) and modulate its activity. The circVAMP3–LDHA interaction facilitated LDHA phosphorylation at tyrosine 10 (Y10) catalyzed by the upstream kinase fibroblast growth factor receptor type 1 (FGFR1). Therefore, this study reveals a novel molecular mechanism by which circVAMP3 promotes glycolysis and proliferation through regulating the enzymatic activity of glycolytic enzyme, suggesting that circVAMP3 may represent an RCC biomarker and treatment target.

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

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

Distinct Response of Circulating microRNAs to the Treatment of Pancreatic Cancer Xenografts with FGFR and ALK Kinase Inhibitors.

Simple SummaryPancreatic cancer is among the top three leading causes of cancer-related death in the United States, mainly due to late diagnosis after the disease has already spread to other organs. Hence, timely and efficient treatments are necessary to improve outcomes. In this study, we explored the use of circulating microRNAs (miRs) collected from the peripheral blood of pancreatic cancer-bearing mice for assessment of treatment efficacy early in the treatment schedule. MicroRNA changes in serum samples precede histologic changes during the treatments, suggesting the use of circulating microRNA as early indicators of response to treatment. These easily-accessible biomarkers can be sampled repeatedly and could guide timely treatment decisions.Pancreatic adenocarcinoma is typically detected at a late stage and thus shows only limited sensitivity to treatment, making it one of the deadliest malignancies. In this study, we evaluate changes in microRNA (miR) patterns in peripheral blood as a potential readout of treatment responses of pancreatic cancer to inhibitors that target tumor–stroma interactions. Mice with pancreatic cancer cell (COLO357PL) xenografts were treated with inhibitors of either fibroblast growth factor receptor kinase (FGFR; PD173074) or anaplastic lymphoma kinase receptor (ALK; TAE684). While both treatments inhibited tumor angiogenesis, signal transduction, and mitogenesis to a similar extent, they resulted in distinct changes in circulating miR signatures. Comparison of the miR pattern in the tumor versus that in circulation showed that the inhibitors can be distinguished by their differential impact on tumor-derived miRs as well as host-derived circulating miRs. Distinct signatures that include circulating miR-1 and miR-22 are associated with the efficacy of ALK and FGFR inhibition, respectively. We propose that monitoring changes in circulating miR profiles can provide an early signature of treatment response or resistance to pathway-targeted drugs, and thus provide a non-invasive measurement to rapidly assess the efficacy of candidate therapies.

Fibroblast growth factor receptor (FGFR) inhibitors as anticancer agents: 3D-QSAR, molecular docking and dynamics simulation studies of 1, 6-naphthyridines and pyridopyrimidines

Fibroblast growth factor receptor (FGFR) plays a vital role in tissue regeneration, angiogenesis, and embryogenesis. 3D-QSAR and molecular modeling methods are widely used for designing novel compounds for the determination of inhibitory activity against the biological target. In the present study, 3D-QSAR (CoMFA and CoMSIA) analysis was performed on 1, 6-naphthyridines, and pyridopyrimidines as potential FGFR inhibitors as anticancer agents. The best CoMFA and CoMSIA models were generated from test and training set derivatives with leave-one-out correlation coefficients (q2 ) 0.591 and 0.667, cross-validated correlation coefficients (r2 cv ) 0.584 and 0.652, conventional coefficients (r2 ncv ) 0.978 and 0.975 respectively. The developed models were validated by a test set of 12 compounds providing acceptable predictive correlation coefficient (r2 pred ) 0.61 and 0.68 for both models. The generated CoMFA and CoMSIA contour maps could be used to design novel 1, 6-naphthyridine analogs. Molecular docking studies indicated that compound 75 occupied the active site of the FGFR kinase interacting with Glu520 in the catalytic region, Asp630 in the DFG motif, and Met524 in the hinge region which compared with standard drug Ponatinib. The molecular dynamics simulation analysis revealed that the inhibitor 75 displayed binding stability in the active site of the FGFR4 by making two hydrogen bonds and one π-cation interaction. Collectively the outcome of the study suggested that the applications of ligand-based and structure-based approaches could be applied for the design of new FGFR4 inhibitors as anticancer agents. Communicated by Ramaswamy H. Sarma

Discovery of a Potent and Highly Isoform-Selective Inhibitor of the Neglected Ribosomal Protein S6 Kinase Beta 2 (S6K2).

Simple SummaryThe two human p70 ribosomal S6 kinases, S6K1 and S6K2, have been associated with a variety of cellular processes and human pathologies, especially cancer. Thus far, only S6K1 was thoroughly studied and selectively addressed by small molecule inhibitors. Despite growing evidence suggesting S6K2 as a promising anticancer target, this isoform has been severely neglected, which can partly be attributed to the lack of isoform-selective inhibitors to study its function. By exploiting a cysteine residue exclusive to S6K2, we were able to generate the first known isoform-selective S6K2 inhibitor. Besides its excellent selectivity against S6K1 and other human kinases, the compound showed weak intrinsic reactivity and promising in vitro metabolic stability. Our proof-of-concept study provides a basis for the development of high quality S6K2 chemical probes to validate this kinase as a target for therapeutic interventions.The ribosomal protein S6 kinase beta 2 (S6K2) is thought to play an important role in malignant cell proliferation, but is understudied compared to its closely related homolog S6 kinase beta 1 (S6K1). To better understand the biological function of S6K2, chemical probes are needed, but the high similarity between S6K2 and S6K1 makes it challenging to selectively address S6K2 with small molecules. We were able to design the first potent and highly isoform-specific S6K2 inhibitor from a known S6K1-selective inhibitor, which was merged with a covalent inhibitor engaging a cysteine located in the hinge region in the fibroblast growth factor receptor kinase (FGFR) 4 via a nucleophilic aromatic substitution (SNAr) reaction. The title compound shows a high selectivity over kinases with an equivalently positioned cysteine, as well as in a larger kinase panel. A good stability towards glutathione and Nα-acetyl lysine indicates a non-promiscuous reactivity pattern. Thus, the title compound represents an important step towards a high-quality chemical probe to study S6K2-specific signaling.

Role of FGF System in Neuroendocrine Neoplasms: Potential Therapeutic Applications.

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors originating from neuroendocrine cells dispersed in different organs. Receptor tyrosine kinases are a subclass of tyrosine kinases with a relevant role in several cellular processes including proliferation, differentiation, motility and metabolism. Dysregulation of these receptors is involved in neoplastic development and progression for several tumors, including NENs. In this review, we provide an overview concerning the role of the fibroblast growth factor (FGF)/fibroblast growth factor receptor (FGFR) system in the development and progression of NENs, the occurrence of fibrotic complications and the onset of drug-resistance. Although no specific FGFR kinase inhibitors have been evaluated in NENs, several clinical trials on multitarget tyrosine kinase inhibitors, acting also on FGF system, showed promising anti-tumor activity with an acceptable and manageable safety profile in patients with advanced NENs. Future studies will need to confirm these issues, particularly with the development of new tyrosine kinase inhibitors highly selective for FGFR.

Targeting FGFR in non-small cell lung cancer: implications from the landscape of clinically actionable aberrations of FGFR kinases.

Objective:Dysfunction in fibroblast growth factor receptor (FGFR) signaling has been reported in diverse cancer types, including non-small cell lung cancer (NSCLC). The frequency of FGFR aberrations in Chinese NSCLC patients is therefore of great clinical significance.Methods:A total of 10,966 NSCLC patients whose tumor specimen and/or circulating cell-free DNA (cfDNA) underwent hybridization capture-based next-generation sequencing were reviewed. Patients’ clinical characteristics and treatment histories were also evaluated.Results:FGFR aberrations, including mutations, fusions, and gene amplifications, were detected in 1.9% (210/10,966) of the population. FGFR abnormalities were more frequently observed in lung squamous cell carcinomas (6.8%, 65/954) than lung adenocarcinomas (1.3%, 128/9,596). FGFR oncogenic mutations were identified in 19 patients (∼0.17%), of which, 68% were male lung squamous cell carcinoma patients. Eleven out of the 19 patients (58%) had concurrent altered PI3K signaling, thus highlighting a potential combination therapeutic strategy of dual-targeting FGFR and PI3K signaling in such patients. Furthermore, FGFR fusions retaining the intact kinase domain were identified in 12 patients (0.11%), including 9 FGFR3-TACC3, 1 FGFR2-INA, 1 novel FGFR4-RAPGEFL1, and 1 novel fusion between the FGFR1 and SLC20A2 5′-untranslated regions, which may have caused FGFR1 overexpressions. Concomitant EGFR mutations or amplifications were observed in 6 patients, and 4 patients received anti-EGFR inhibitors, in whom FGFR fusions may have mediated resistance to anti-EGFR therapies. FGFR amplification was detected in 24 patients, with the majority being FGFR1 amplifications. Importantly, FGFR oncogenic mutations, fusions, and gene amplifications were almost always mutually exclusive events.Conclusions:We report the prevalence of FGFR anomalies in a large NSCLC population, including mutations, gene amplifications, and novel FGFR fusions.

Acute Kidney Injury Sensitizes the Brain Vasculature to Ang II (Angiotensin II) Constriction via FGFBP1 (Fibroblast Growth Factor Binding Protein 1).

Acute kidney injury (AKI) causes multiple organ dysfunction. Here, we identify a possible mechanism that can drive brain vessel injury after AKI. We induced 30-minute bilateral renal ischemia-reperfusion injury in C57Bl/6 mice and isolated brain microvessels and macrovessels 24 hours or 1 week later to test their responses to vasoconstrictors and found that after AKI brain vessels were sensitized to Ang II (angiotensin II). Upregulation of FGF2 (fibroblast growth factor 2) and FGFBP1 (FGF binding protein 1) expression in both serum and kidney tissue after AKI suggested a potential contribution to the vascular sensitization. Administration of FGF2 and FGFBP1 proteins to isolated healthy brain vessels mimicked the sensitization to Ang II after AKI. Brain vessels in Fgfbp1-/- AKI mice failed to induce Ang II sensitization. Complementary to this, systemic treatment with the clinically used FGF receptor kinase inhibitor BGJ398 (Infigratinib) reversed the AKI-induced brain vascular sensitization to Ang II. All these findings lead to the conclusion that FGFBP1 is especially necessary for AKI-mediated brain vascular sensitization to Ang II and inhibitors of FGFR pathway may be beneficial in preventing AKI-induced brain vessel injury.

Design and Synthesis of Novel Nordihydroguaiaretic Acid (NDGA) Analogues as Potential FGFR1 Kinase Inhibitors With Anti-Gastric Activity and Chemosensitizing Effect.

Aberrant fibroblast growth factor receptor-1 (FGFR1), a key driver promoting gastric cancer (GC) progression and chemo-resistance, has been increasingly recognized as a potential therapeutic target in GC. Hereon, we designed and synthesized a series of asymmetric analogues using Af23 and NDGA as lead compounds by retaining the basic structural framework (bisaryl-1,4-dien-3-one) and the unilateral active functional groups (3,4-dihydroxyl). Thereinto, Y14 showed considerable inhibitory activity against FGFR1. Next, pharmacological experiments showed that Y14 could significantly inhibit the phosphorylation of FGFR1 and its downstream kinase AKT and ERK, thus inhibiting the growth, survival, and migration of gastric cancer cells. Furthermore, compared with 5-FU treatment alone, the combination of Y14 and 5-FU significantly reduced the phosphorylation level of FGFR1, and enhanced the anti-cancer effect by inhibiting the viability and colony formation in two gastric cancer cell lines. These results confirmed that Y14 exerted anti-gastric activity and chemosensitizing effect by inhibiting FGFR1 phosphorylation and its downstream signaling pathway in vitro. This work also provides evidence that Y14, an effective FGFR1 inhibitor, could be used alone or in combination with chemotherapy to treat gastric cancer in the future.