Fibroblast Growth Factor Receptor Inhibitors Research Articles

Targeting the fibroblast growth factor pathway in molecular subtypes of castration-resistant prostate cancer.

Androgen receptor (AR) pathway inhibition remains the cornerstone for prostate cancer therapies. However, castration-resistant prostate cancer (CRPC) tumors can resist AR signaling inhibitors through AR amplification and AR splice variants in AR-positive CRPC (ARPC), and conversion to AR-null phenotypes, such as double-negative prostate cancer (DNPC) and small cell or neuroendocrine prostate cancer (SCNPC). We have shown previously that DNPC can bypass AR-dependence through fibroblast growth factor receptor (FGFR) signaling. However, the role of the FGFR pathway in other CRPC phenotypes has not been elucidated. RNA-Seq analysis was conducted on patient metastases, LuCaP patient-derived xenograft (PDX) models, and CRPC cell lines. Cell lines (C4-2B, VCaP, and 22Rv1) and ex vivo LuCaP PDX tumor cells were treated with enzalutamide (ENZA) and FGFR inhibitors (FGFRi) alone or in combination and sensitivity was determined using cell viability assays. In vivo efficacy of FGFRi in ARPC, DNPC, and SCNPC were evaluated using PDX models. RNA-Seq analysis of FGFR signaling in metastatic specimens, LuCaP PDX models, and CRPC cell lines revealed significant FGF pathway activation in AR-low PC (ARLPC), DNPC, and SCNPC tumors. In vitro/ex vivo analysis of erdafitinib and CH5183284 demonstrated robust and moderate growth suppression of ARPC, respectively. In vivo studies using four ARPC PDX models showed that combination ENZA and CH5183284 significantly suppressed tumor growth. Additional in vivo studies using four ARPC PDX models revealed that erdafitinib monotherapy was as effective as ENZA in suppressing tumor growth, and there was limited combination benefit. Furthermore, two of three DNPC models and two of four SCNPC models responded to CH5183284 monotherapy, suggesting FGFRi responses were model dependent. RNA-Seq and gene set enrichment analysis of end-of-study ARPC tumors treated with FGFRi displayed decreased expression of E2F and MYC target genes and suppressed G2M checkpoint genes, whereas end-of-study SCNPC tumors had heterogeneous transcriptional responses. Although FGFRi treatments suppressed tumor growth across CRPC phenotypes, our analyses did not identify a single pathway or biomarker that would identify tumor response to FGFRi. This is very likely due to the array of FGFR1-4 expression and tumor phenotypes present in CRPC. Nevertheless, our data nominate the FGFR pathway as a clinically actionable target that promotes tumor growth in diverse phenotypes of treatment-refractory metastatic CRPC.

The Effects of Fibroblast Growth Factor-2 (FGF-2) on Achilles Tendon Injury

Category: Basic Sciences/Biologics; Ankle Introduction/Purpose: Achilles tendon defects are a challenging problem, and there is a need for new treatments. We investigated the use of Platelet-rich fibrin (PRF), a dense fibrin scaffold containing many growth factors and cytokines, for Achilles tendon injuries. The study found that PRF accelerates healing by promoting the proliferation and activation of tenocytes via FGF receptor/AKT signaling and TGF-β/SMAD3 signaling. While FGF-2, a growth factor in PRF, has been shown to promote tenocyte differentiation and proliferation, its effect on Achilles tendon injuries has not been reported. Therefore, this study aimed to investigate the effect of FGF-2 on Achilles tendon healing when administered alone and to determine its specific contribution to the healing process. Methods: We used a rat model of Achilles tendon defect. A 4-mm portion of the right Achilles tendon, 4 mm proximal to the calcaneal insertion, was resected to create a tendon defect. Gelatin hydrogel sheet (MedGel PI5) as a scaffold for PBS, FGF-2 (Rigroth®), and FGF receptor inhibitor (FGFRI: Pemigatinib) was placed into the gap before suturing it with nylon sutures. We observed HE-stained specimens at 200x and assessed histological healing by counting cells and vessels and grading cell morphology. The motor function was evaluated by the Basso, Beattie, and Bresnahan (BBB) score and the treadmill test. We compared the effects of FGF-2 on tenocytes isolated from rat Achilles tendons in the control, FGF2, and FGFRI groups. The proliferation and migration of tenocytes were measured by MTS assay and wound closure assay, respectively. Protein expression, such as Tenomodulin (Tnmd), Collagen Ⅰ, Ⅲ, and Screlaxis-A in cells, were evaluated by Western Blotting. Results: In the rat model, the number of cells, vessels and cell morphology scores at the defect sites increased in the FGF-2 group and decreased in the FGFRI group at 2 and 4 weeks postoperatively. In the motor functional evaluation, the FGF-2 group showed earlier improvement in the BBB score and the treadmill test compared to the control and FGFRI groups. The MTS assay showed that the number of viable cells was higher in the FGF-2 group and lower in the FGFRI group than in the control. Wound closure assay showed tenocyte migration was increased in the FGF-2 group and decreased in the FGFRI group. Regarding protein expression, Tnmd, Collagen I, III, and Screlaxis-A were increased in the FGF-2 group and decreased in the FGFRI group. Conclusion: In vivo, FGF-2 promoted healing of Achilles tendon injury, and FGFRI impeded it in terms of motor function and histology. Additionally, in vitro, FGF-2 promoted the proliferation and migration of tenocytes and enhanced extracellular matrix production, while FGFRI diminished these effects. Although native FGF-2 is produced at the injured site, further administration of FGF-2 accelerated Achilles tendon injury healing, while inhibiting the FGF receptor delayed recovery in this study. Therefore, FGF- 2 is very important in Achilles tendon injury healing and may promote recovery by enhancing angiogenesis, proliferation, and extracellular matrix production of tenocytes.

95MO Tinengotinib in patients with advanced, fibroblast growth factor receptor (FGFR) inhibitor refractory/relapsed cholangiocarcinoma

95MO Tinengotinib in patients with advanced, fibroblast growth factor receptor (FGFR) inhibitor refractory/relapsed cholangiocarcinoma

Targeting FGFR Pathways in Gastrointestinal Cancers: New Frontiers of Treatment.

In carcinogenesis of the gastrointestinal (GI) tract, the deregulation of fibroblast growth factor receptor (FGFR) signaling plays a critical role. The aberrant activity of this pathway is described in approximately 10% of gastric cancers and its frequency increases in intrahepatic cholangiocarcinomas (iCCAs), with an estimated frequency of 10-16%. Several selective FGFR inhibitors have been developed in the last few years with promising results. For example, targeting the FGFR pathway is now a fundamental part of clinical practice when treating iCCA and many clinical trials are ongoing to test the safety and efficacy of anti-FGFR agents in gastric, colon and pancreatic cancer, with variable results. However, the response rates of anti-FGFR drugs are modest and resistances emerge rapidly, limiting their efficacy and causing disease progression. In this review, we aim to explore the landscape of anti-FGFR inhibitors in relation to GI cancer, with particular focus on selective FGFR inhibitors and drug combinations that may lead to overcoming resistance mechanisms and drug-induced toxicities.

Discovery of Novel Naphthoquinone-Chalcone Hybrids as Potent FGFR1 Tyrosine Kinase Inhibitors: Synthesis, Biological Evaluation, and Molecular Modeling.

This work presents a flexible synthesis of 10 novel naphthoquinone-chalcone derivatives (1-10) by nucleophilic substitution of readily accessible aminochalcones and 2,3-dichloro-1,4-naphthoquinone. All compounds displayed broad-spectrum cytotoxic activities against all the tested cancer cell lines (i.e., HuCCA-1, HepG2, A549, MOLT-3, T47D, and MDA-MB-231) with IC50 values in the range of 0.81-62.06 μM, especially the four most potent compounds 1, 3, 8, and 9. The in vitro investigation on the fibroblast growth factor receptor 1 (FGFR1) inhibitory effect indicated that eight derivatives (1-2, 4-5, and 7-10) were active FGFR1 inhibitors (IC50 = 0.33-3.13 nM) with more potency than that of the known FGFR1 inhibitor, AZD4547 (IC50 = 12.17 nM). Promisingly, compounds 5 (IC50 = 0.33 ± 0.01 nM), 9 (IC50 = 0.50 ± 0.04 nM), and 7 (IC50 = 0.85 ± 0.08 nM) were the three most potent FGFR1 inhibitors. Molecular docking, molecular dynamics simulations, and MM/GBSA-based free energy calculation revealed that the key amino acid residues involved in the binding of the compounds 5, 7, and 9 and the target FGFR1 protein were similar with those of the AZD4547 (i.e., Val492, Lys514, Ile545, Val561, Ala640, and Asp641). These findings revealed that the newly synthesized naphthoquinone-chalcone scaffold is a promising structural feature for an efficient inhibition of FGFR1.

Avelumab as First-Line Maintenance Treatment in Locally Advanced or Metastatic Urothelial Carcinoma.

This work provides a summary of guideline recommendations and an expert position on the use of maintenance avelumab therapy based on a review of current international clinical practice guidelines for locally advanced or metastatic urothelial carcinoma (UC). A PubMed literature search was conducted in March 2022 (updated in July 2023) to identify guidelines for locally advanced or metastatic UC. An expert panel (four oncologists and one urologist) reviewed the guidelines and clinical evidence, and discussed practical questions regarding the use of avelumab maintenance therapy in this clinical setting. The National Comprehensive Cancer Network, European Association of Urology and European Society for Medical Oncology guidelines recommend first-line cisplatin-containing chemotherapy for cisplatin-eligible patients, carboplatin-gemcitabine for cisplatin-ineligible patients who are fit for carboplatin, or immunotherapy with programmed death ligand-1 (PD-L1) inhibitors (e.g. atezolizumab) in platinum-ineligible patients. Maintenance avelumab is recommended in patients with response/stable disease following chemotherapy (regardless of PD-L1 status). In patients who relapse after/during chemotherapy, options include immunotherapy, erdafitinib [in those with fibroblast growth factor receptor (FGFR) mutations], enfortumab vedotin or further chemotherapy. The expert panel provided the following practical guidance: (1) consider maintenance avelumab in all eligible patients; (2) continue avelumab until disease progression/unacceptable toxicity; (3) ideally, administer six cycles of platinum-based chemotherapy prior to maintenance avelumab; (4) perform radiological evaluation after four chemotherapy cycles and prior to maintenance avelumab; (5) carboplatin-gemcitabine followed by maintenance avelumab is preferred in cisplatin-ineligible patients (regardless of PD-L1 expression), but consider first-line immunotherapy in PD-L1-positive patients and platinum-ineligible patients (regardless of PD-L1 status); and (6) for patients who relapse on avelumab, second-line options include enfortumab vedotin, FGFR inhibitors (in those with FGFR mutations) or clinical trial inclusion. In conclusion, avelumab maintenance therapy is recommended following platinum-based chemotherapy in all eligible patients with locally advanced or metastatic UC, continued until disease progression or unacceptable toxicity.

Do Cancer Genetics Impact Treatment Decision Making? Immunotherapy and Beyond in the Management of Advanced and Metastatic Urothelial Carcinoma.

Bladder cancer is one of the most commonly diagnosed genitourinary malignancies. For many years, the primary treatment for metastatic urothelial cancer (mUC) was predicated on the use of platinum-based chemotherapy. More recently, immune checkpoint inhibitors (ICIs) were approved by regulatory agencies such as the US FDA for use in both the first- and second-line settings. This review outlines the approved ICIs for mUC in the second-line setting and as an alternative to chemotherapy in the first-line setting, as well as the novel agents that have also been incorporated into the treatment of this malignancy. Single-agent ICIs are often used in second-line settings in mUC, and there are three drugs currently approved for those who progress after receiving platinum-based chemotherapy. In the first-line setting, the preferred treatment regimen remains cisplatin-based chemotherapy. However, single-agent ICI can be an alternative first-line treatment for those who are not candidates for cisplatin-based therapy. There are also clinical trials adding ICIs to chemotherapy as combination regimens. However, treatment for mUC has now expanded even beyond immunotherapy. Newer targeted agents such as erdafitinib, a fibroblast growth factor receptor inhibitor, and two antibody-drug conjugates, enfortumab vedotin and sacituzumab govitecan, have been recently approved. As new drug agents are discovered, it will be important to assess both the treatment outcomes as well as the effects on patients' quality of life. Furthermore, integrating genetic and molecular information can help guide treatment decisions as next-generation sequencing is more commonly acquired during the evaluation of newly diagnosed patients with advanced and metastatic cancer.

Efficacy of fibroblast growth factor receptor (FGFR) inhibitors therapy in advanced cholangiocarcinoma with FGFR genes alterations: A meta-analysis of phase II clinical trials.

54 Background: Fibroblast growth factor receptor ( FGFR) gene fusions and rearrangements are involved in the pathogenesis of approximately 10 to 16 percent of patients with cholangiocarcinoma. There is no meta-analysis available of phase 2 clinical trials of FGFR inhibitors in these patients. In this article, we analyze the efficacy of FGFR inhibitors in advanced cholangiocarcinoma with FGFR gene fusions or other rearrangements. Methods: Systemic searches of PubMed, Embase, the Cochrane Library, Google Scholar, and ClinicalTrials.gov were conducted with prespecified terms. The outcomes studied in our analysis were Objective response rate (ORR), Disease control rate (DCR), Progression-free survival (PFS), and Overall survival (OS). We calculated the pooled ORR for these studies by using weighted average ORR = Σ (ORR_i * weight_i). Calculate the standard error using the formula SE = √(Σ (wi x (1 - ORRi) x ORRi) / Σ (wi x ni)) and the 95% confidence interval using the formula CI = ORR ± (1.96 x SE). However, it is important to note that the pooled ORR is only as reliable as the individual ORR estimates from each study and may be subject to bias or confounding factors. This method was used to calculate the pooled DCR, PFS, and OS for our study as well. All data extraction and calculations were verified by three reviewers. Results: Eight phase II clinical trials met the inclusion criteria (1-8). Outcome data were available for all eight studies, comprising 562 patients with FGFR-positive advanced cholangiocarcinoma who received FGFR-targeted treatment regimens. The pooled objective response rate (ORR) and disease control rate (DCR) were 32.6% (95% CI 28.1-37.1) and 81.86% (95% CI 74.96-88.76), respectively. The pooled weighted progression-free survival (PFS) was 7.5 months, and pooled overall survival (OS) was 17.4 months. These findings suggest that FGFR-targeted treatment regimens have a promising ORR, DCR, PFS, and OS. Conclusions: FGFR inhibitors as a class in patients with advanced or metastatic cholangiocarcinoma with FGFR gene alterations showed clinically meaningful efficacy with durable objective responses. [Table: see text]

Infigratinib, a Selective Fibroblast Growth Factor Receptor Inhibitor, Suppresses Stent-Induced Tissue Hyperplasia in a Rat Esophageal Model.

Stent-induced tissue hyperplasia remains a challenge for the application of self-expanding metal stents in the management of esophageal stricture. This study aimed to evaluate the efficacy of infigratinib, which is a selective fibroblast growth factor receptor inhibitor, in the prevention of stent-induced tissue hyperplasia in a rat esophageal model. Twenty-four male Sprague-Dawley rats underwent esophageal stent placement and were randomized to receive 1ml of vehicle, 5mg/kg infigratinib in 1ml of vehicle, or 10mg/kg infigratinib in 1ml of vehicle via naso-gastric tube once daily for 28days. Follow-up fluoroscopy was performed on postoperative day 28, and the stented esophageal tissues were harvested for histological and immunofluorescence examinations. All rats survived until euthanasia on postoperative day 28 without procedure-related adverse events. The incidence of stent migration was 12.5%, 12.5% and 25% in the control group, the 5mg/kg infigratinib group and, the 10mg/kg infigratinib group, respectively. The percentage of granulation tissue area, the submucosal fibrosis thickness, the number of epithelial layers, the degree of inflammatory cell infiltration, the degree of collagen deposition, the number of fibroblast growth factor receptor 1 (FGFR1)-expressing myofibroblasts, and the number of proliferating myofibroblasts were all significantly lower in both infigratinib groups than in the control group (P < 0.05) but were not significantly different between the two infigratinib groups (P > 0.05). Infigratinib significantly suppresses stent-induced tissue hyperplasia by inhibiting FGFR1-mediated myofibroblast proliferation and profibrotic activities in a rat esophageal model.

Efficacy of combined targeted therapy with PI3K and CDK4/6 or PARP and WEE1 inhibitors in neuroblastoma cell lines.

Neuroblastoma (NB), the most frequent solid extracranial tumor in children, is not always cured by current aggressive therapies that have notable adverse effects; therefore, novel treatments are necessary. Phosphoinositide 3‑kinase (PI3K) and fibroblast growth factor receptor inhibitors exhibit synergistic effect in NB cell lines. In the present study, mono‑ and combination therapy of the United States Food and Drug Administration‑approved PI3K, cyclin‑dependent kinase‑4/6 (CDK4/6), poly‑ADP‑ribose‑polymerase (PARP) and WEE1 G2 checkpoint kinase (WEE1) inhibitors (BYL719, PD‑0332991, BMN673 and MK‑1775, respectively), were used to treat NB cell lines SK‑N‑AS, SK‑N‑BE(2)‑C, SK‑N‑DZ, SK‑N‑FI and SK‑N‑SH and viability (assessed by WST‑1 assay), proliferation (incucyte analysis) and cell cycle (FACS) changes were assessed. Treatments with all single drugs presented dose‑-dependent responses with decreased viability and proliferation and combining BYL719 with PD‑0332991 or BMN673 with MK‑1775 resulted in additive or synergistic effects in most cell lines., except for SK‑N‑SH for the former and for SK‑N‑AS for the latter. Moreover, combining MK‑1775 and BMN673 decreased the numbers of cells in S phase to a greater extent than either drug alone, while when combining PD‑0332991 and BYL719 the observed effect was close to that of PD‑0332991 alone. To summarize, PI3K and CDK4/6 or PARP and WEE1 exhibited synergistic anti‑NB effects and lower doses of the inhibitors could be utilized, thereby potentially reducing adverse side effects.

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.

Discovery and Structural Optimization of Novel Quinolone Derivatives as Potent Irreversible Pan-Fibroblast Growth Factor Receptor Inhibitors for Treating Solid Tumors.

Aberrant activation of fibroblast growth factor receptors (FGFRs) has been identified as an oncogenic driver force for multiple cancer types, making FGFRs a compelling target for anticancer therapy. Because of the renewed interest in irreversible inhibitors, considerable efforts have been made to find irreversible FGFR inhibitors. Herein, we discovered a series of novel quinolone-based covalent pan-FGFR inhibitors by further optimizing the lead compound (lenvatinib) under the guidance of molecular docking. The representative pan-FGFR inhibitor I-5 exhibited significant inhibitory potency against FGFR1-4 with nanomolar activity and effectively suppressed the proliferation of Huh-7 and Hep3B HCC cells. I-5 displayed high selectivity against a panel of 369 kinases at 1 μM. The irreversible binding to target proteins was characterized by liquid chromatography and tandem mass spectrometry (LC-MS/MS). Moreover, I-5 exhibited favorable PK properties in vivo and induced significant TGI in the Huh-7 and NCI-H1581 xenograft mouse models.

The FGFR inhibitor PD173074 binds to the C-terminus of oncofetal HMGA2 and modulates its DNA-binding and transcriptional activation functions.

The architectural chromatin factor high-mobility group AT-hook 2 (HMGA2) is causally involved in several human malignancies and pathologies. HMGA2 is not expressed in most normal adult somatic cells, which renders the protein an attractive drug target. An established cell-based compound library screen identified the fibroblast growth factor receptor (FGFR) inhibitor PD173074 as an antagonist of HMGA2-mediated transcriptional reporter gene activation. We determined that PD173074 binds the C-terminus of HMGA2 and interferes with functional coordination of the three AT-hook DNA-binding domains mediated by the C-terminus. The HMGA2-antagonistic effect of PD173074 on transcriptional activation may therefore result from an induced altered DNA-binding mode of HMGA2. PD173074 as a novel HMGA2-specific antagonist could trigger the development of derivates with enhanced attributes and clinical potential.

RLY-4008, the First Highly Selective FGFR2 Inhibitor with Activity across FGFR2 Alterations and Resistance Mutations.

Patients with FGFR2-driven cancers derive limited benefit from pan-FGFRi due to multiple FGFR1-4-mediated toxicities and acquired FGFR2 resistance mutations. RLY-4008 is a highly selective FGFR2 inhibitor that targets primary alterations and resistance mutations and induces tumor regression while sparing other FGFRs, suggesting it may have broad therapeutic potential. See related commentary by Tripathi et al., p. 1964. This article is featured in Selected Articles from This Issue, p. 1949.

Evaluating the use of circulating tumor DNA (ctDNA) in patients with urothelial cancer in the context of FGFR-targeted therapy.

4577 Background: Fibroblast growth factor receptor (FGFR) inhibitors (e.g., erdafitinib) are increasingly important in the management of FGFR-mutated urothelial carcinoma. FDA-approved archival tissue testing for specific FGFR alterations was implemented as a companion diagnostic for erdafitinib. However, longitudinal sequencing studies indicate variable tumor FGFR status over time, and erdafitinib resistance mechanisms in metastatic urothelial carcinoma (mUC) are underreported. This ongoing study aims to evaluate the accuracy of cell-free DNA (cfDNA) compared to archival tissue testing in mUC for FGFR alterations detection, and to evaluate genomic mechanisms of erdafitinib resistance in cfDNA at progression. Methods: Patients with progressing mUC who were undergoing archival tissue testing for FGFR1-3 mutations and/or fusions and who had blood samples drawn during the management of their metastatic disease were eligible. Plasma cfDNA and matched leukocyte DNA were subjected to deep targeted sequencing with a custom panel including UC-specific gene loci and all clinically approved hotspots in FGFR1+2 and all exons and introns of FGFR3. Results: As of January 2023, 109 patients from 6 sites were enrolled. Median age at diagnosis was 71, 33% had upper urinary tract primaries, and 76% were male. Tissue and cfDNA results for comparison were available for 69 patients to date. Actionable somatic FGFR alterations were found in the tissue of 15 patients (31%); the most common alteration was the FGFR3 p.S249C mutation (67%). 50 of the analyzed cfDNA samples had detectable somatic circulating tumor DNA (ctDNA) variant allele fraction of 0.5% (72%). Of those, 49 had an evaluable tissue test result. Analysis of this subset revealed high concordance (92%) between the two test methods. With the assumption that archival tissue testing is considered the ‘gold standard’, sensitivity is 93% and specificity is 91%. The four discordant results comprised one cfDNA test with undetectable FGFR3-TACC3 fusion, which was detected in tissue and three positive ctDNA test results in patients with FGFR wild-type tissue tests. In one case at erdafitinib progression, ctDNA revealed multiple subclonal populations with distinct FGFR3 gatekeeper mutations suggesting polyclonal resistance. Conclusions: This ongoing study suggests cfDNA is a valuable minimally invasive adjunct to tissue-based assays for the detection of FGFR alterations to identify patients for FGFR inhibitor therapy and to monitor for mechanisms of resistance.

A phase 0 pharmacokinetic trigger trial of infigratinib in patients with recurrent high-grade glioma.

2051 Background: This Phase 0 trial evaluates tumor pharmacokinetic (PK) and pharmacodynamic (PD) responses of fibroblast growth factor receptor (FGFR) inhibitor, infigratinib, in participants with recurrent high-grade glioma carrying FGFR1 K656E or FGFR3 K650E mutation or FGFR3-TACC3 translocation. Patients with high unbound drug concentrations in the gadolinium-nonenhancing tumor region were graduated to a therapeutic regimen of infigratinib. Methods: Recurrent high-grade glioma patients received 7 days of infigratinib (125 mg QD) prior to planned resection at 7-9 hours following the last dose. Tumor tissue (enhancing and nonenhancing regions), cerebrospinal fluid (CSF), and plasma were collected. Total and unbound infigratinib concentrations were measured using validated LC-MS/MS methods. A PK ‘trigger’ determined eligibility for the therapeutic expansion phase and was defined as unbound [infigratinib] &gt; 5-fold biochemical IC50 (i.e., 5 nM) in non-enhancing tumor. PD response was assessed by quantification of percentage of positive pERK, MIB-1, and Cleaved Caspase 3 cells in the surgical tissue compared to baseline archival/biopsy tissue. Patients with tumors exceeding the PK threshold for unbound drug concentration were eligible for expansion phase therapeutic dosing of infigratinib. Results: Seven patients were enrolled into the Phase 0 study with 3 patients who met the PK threshold continued to the expansion phase. In non-enhancing tumor region, the mean unbound concentration of infigratinib was 3.5 nM (n=7). The mean non-enhancing tumor-to-plasma coefficient for unbound drug (Kp,uu) was calculated to be 1.4. The suppression of pERK levels and MIB-1 levels was observed in 17% (1/6) and 67% (4/6) of the patients, respectively. At a median follow-up of 16.3 months [range: 2.8-18.7 months], the median progression-free survival (PFS) was 2.8 months (n=3). One patient remains on treatment. No grade 3+ toxicities were observed, and no adverse events resulted in discontinuation of therapy. Conclusions: Despite relatively high unbound tumor-to-plasma (Kp,uu) value, infigratinib achieves sub-optimal unbound drug concentration in the non-enhancing brain tumor tissue. Pharmacodynamic response with archival tissue as comparator did not reveal inhibition of pERK. Clinical trial information: NCT04424966 .

Endogenous FGF21 attenuates blood-brain barrier disruption in penumbra after delayed recanalization in MCAO rats through FGFR1/PI3K/Akt pathway.

Restoration of blood circulation within "time window" is the principal treating goal for treating acute ischemic stroke. Previous studies revealed that delayed recanalization might cause serious ischemia/reperfusion injury. However, plenty of evidences showed delayed recanalization improved neurological outcomes in acute ischemic stroke. This study aims to explore the role of delayed recanalization on blood-brain barrier (BBB) in the penumbra (surrounding ischemic core) and neurological outcomes after middle cerebral artery occlusion (MCAO). Recanalization was performed on the 3rd day after MCAO. BBB disruption was tested by Western blotting, Evans blue dye, and immunofluorescence staining. Infarct volume and neurological outcomes were evaluated on the 7th day after MCAO. The expression of fibroblast growth factor 21 (FGF21), fibroblast growth factor receptor 1 (FGFR1), phosphatidylinositol-3-kinase (PI3K), and serine/threonine kinase (Akt) in the penumbra were observed by immunofluorescence staining and/or Western blotting. The extraversion of Evans blue, IgG, and albumin increased surrounding ischemic core after MCAO, but significantly decreased after recanalization. The expression of Claudin-5, Occludin, and zona occludens 1 (ZO-1) decreased surrounding ischemic core after MCAO, but significantly increased after recanalization. Infarct volume reduced and neurological outcomes improved following recanalization (on the 7th day after MCAO). The expressions of Claudin-5, Occludin, and ZO-1 decreased surrounding ischemic core following MCAO, which were up-regulated corresponding to the increases of FGF21, p-FGFR1, PI3K, and p-Akt after recanalization. Intra-cerebroventricular injection of FGFR1 inhibitor SU5402 down-regulated the expression of PI3K, p-Akt, Occludin, Claudin-5, and ZO-1 in the penumbra, which weakened the beneficial effects of recanalization on neurological outcomes after MCAO. Delayed recanalization on the 3rd day after MCAO increases endogenous FGF21 in the penumbra and activates FGFR1/PI3K/Akt pathway, which attenuates BBB disruption in the penumbra and improves neurobehavior in MCAO rats.

Whole exome and transcriptome analysis revealed the activation of ERK and Akt signaling pathway in canine histiocytic sarcoma

Histiocytic sarcoma (HS) is an incurable aggressive tumor, and no consensus has been made on the treatment due to its rare occurrence. Since dogs spontaneously develop the disease and several cell lines are available, they have been advocated as translational animal models. In the present study, therefore, we explored gene mutations and aberrant molecular pathways in canine HS by next generation sequencing to identify molecular targets for treatment. Whole exome sequencing and RNA-sequencing revealed gene mutations related to receptor tyrosine kinase pathways and activation of ERK1/2, PI3K-AKT, and STAT3 pathways. Analysis by quantitative PCR and immunohistochemistry revealed that fibroblast growth factor receptor 1 (FGFR1) is over-expressed. Moreover, activation of ERK and Akt signaling were confirmed in all HS cell lines, and FGFR1 inhibitors showed dose-dependent growth inhibitory effects in two of the twelve canine HS cell lines. The findings obtained in the present study indicated that ERK and Akt signaling were activated in canine HS and drugs targeting FGFR1 might be effective in part of the cases. The present study provides translational evidence that leads to establishment of novel therapeutic strategies targeting ERK and Akt signaling in HS patients.

Erdafitinib treatment in metastatic urothelial carcinoma: a real-world analysis.

Erdafitinib, a fibroblast growth factor receptor (FGFR) inhibitor is a standard post chemotherapy advanced treatment line for metastatic urothelial carcinoma harboring FGFR2/3 genomic alterations. It was approved based on a phase 2 clinical trial, revealing a 40% response rate, and 13.8 months overall survival. These FGFR genomic alterations are uncommon. Thus, real-world data on erdafitinb use is scant. We herein describe erdafitinib treatment outcome in a real world patient cohort. We retrospectively reviewed the data of patients treated with erdafitinib from 9 Israeli medical centers. Twenty-five patients with metastatic urothelial carcinoma (median age 73, 64% male, 80% with visceral metastases) were treated with erdafitinib between January 2020 to October 2022. A clinical benefit (complete response 12%, partial response 32%, stable disease 12%) was seen in 56%. Median progression-free survival was 2.7 months, and median overall survival 6.73 months. Treatment related toxicity ≥ grade 3 occurred in 52%, and 32% discontinued therapy due to adverse events. Erdafitinib therapy is associated with a clinical benefit in the real world setting, and associated with similar toxicity as reported in prospective clinical trials.

FGF2 activity regulates operant alcohol self-administration and mesolimbic dopamine transmission

Fibroblast growth factor 2 (FGF2) is involved in the development and maintenance of the brain dopamine system. We previously showed that alcohol exposure alters the expression of FGF2 and its receptor, FGF receptor 1 (FGFR1) in mesolimbic and nigrostriatal brain regions, and that FGF2 is a positive regulator of alcohol drinking. Here, we determined the effects of FGF2 and of FGFR1 inhibition on alcohol consumption, seeking and relapse, using a rat operant self-administration paradigm. In addition, we characterized the effects of FGF2-FGFR1 activation and inhibition on mesolimbic and nigrostriatal dopamine neuron activation using in vivo electrophysiology. We found that recombinant FGF2 (rFGF2) increased the firing rate and burst firing activity of dopaminergic neurons in the mesolimbic and nigrostriatal systems and led to increased operant alcohol self-administration. In contrast, the FGFR1 inhibitor PD173074 suppressed the firing rate of these dopaminergic neurons, and reduced operant alcohol self-administration. Alcohol seeking behavior was not affected by PD173074, but this FGFR1 inhibitor reduced post-abstinence relapse to alcohol consumption, albeit only in male rats. The latter was paralleled by the increased potency and efficacy of PD173074 in inhibiting dopamine neuron firing. Together, our findings suggest that targeting the FGF2-FGFR1 pathway can reduce alcohol consumption, possibly via altering mesolimbic and nigrostriatal neuronal activity.