Fibroblast Growth Factor Receptor Inhibitors Research Articles

Targeting CERS6-AS1/FGFR1 axis as synthetic vulnerability to constrain stromal cells supported proliferation in Mantle cell lymphoma.

The interaction between stromal and tumor cells in tumor microenvironment is a crucial factor in Mantle cell lymphoma (MCL) progression and therapy resistance. We have identified a long non-coding RNA, CERS6-AS1, upregulated in MCL and associated with poor overall survival. CERS6-AS1 expression was elevated in primary MCL within stromal microenvironment and in a subset of MCL cells adhered to stromal layer. These stromal-adhered MCL-subsets exhibited cancer stem cell signatures than suspension counterparts. Mechanistically, we found that downregulating CERS6-AS1 in MCL reduced Fibroblast Growth Factor Receptor-1 (FGFR1), expression attributed to loss of its interaction with RNA-binding protein nucleolin. In addition, using in-silico approach, we have discovered a direct interaction between nucleolin and 5'UTR of FGFR1, thereby regulating FGFR1 transcript stability. We discovered a positive association of CERS6-AS1 with cancer stem cell signatures, and Wnt signaling. Building on these, we explored potential therapeutic strategies where combining nucleolin-targeting agent with FGFR1 inhibition significantly contributed to reversing cancer stem cell signatures and abrogated primary MCL cell growth on stromal layer. These findings provide mechanistic insights into regulatory network involving CERS6-AS1, nucleolin, and FGFR1 axis-associated crosstalk between tumor cells and stromal cell interaction and highlights therapeutic potential of targeting a non-coding RNA in MCL.

Differential effects of the N-terminal helix of FGF8b on the activity of a small-molecule FGFR inhibitor in cell culture and for the extracellular domain of FGFR3c in solution.

SSR128129E (SSR) is a unique small-molecule inhibitor of fibroblast growth factor receptors (FGFRs). SSR is a high-affinity allosteric binder that selectively blocks one of the two major FGFR-mediated pathways. The mechanisms of SSR activity were studied previously in much detail, allowing the identification of its binding site, located in the hydrophobic groove of the receptor D3 domain. The binding site overlaps with the position of an N-terminal helix, an element exclusive for the FGF8b growth factor, which could potentially convert SSR from an allosteric inhibitor into an orthosteric blocker for the particular FGFR/FGF8b system. In this regard, we report here on the structural and functional investigation of FGF8b/FGFR3c system and the effects imposed on it by SSR. We show that SSR is equally or more potent in inhibiting FGF8b-induced FGFR signaling compared to FGF2-induced activation. On the other hand, when studied in the context of separate extracellular domains of FGFR3c in solution with NMR spectroscopy, SSR is unable to displace the N-terminal helix of FGF8b from its binding site on FGFR3c and behaves as a weak orthosteric inhibitor. The substantial inconsistency between the results obtained with cell culture and for the individual water-soluble subdomains of the FGFR proteins points to the important role played by the cell membrane.

Successful intrahepatic cholangiocarcinoma conversion surgery after administration of fibroblast growth factor receptor inhibitor.

We describe a case of a 47-year-old male patient with initially unresectable intrahepatic cholangiocarcinoma of the right liver lobe with tumor thrombi extending from the right bile duct to the common and left bile ducts. Conventional chemotherapy with gemcitabine and cisplatin for 19months resulted in progressive disease. Subsequently, a comprehensive genome profile revealed fibroblast growth factor receptor 2 rearrangement, and hence, pemigatinib administration was initiated. After 6months of pemigatinib therapy, significant shrinking of the tumor and disappearance of the tumor thrombi in the common and left bile duct were observed. Subsequently, the patient underwent conversion surgery, resulting in successful radical resection of the tumor. The patient has been disease-free for 7months.

Successful intrahepatic cholangiocarcinoma conversion surgery after administration of fibroblast growth factor receptor inhibitor.

We describe a case of a 47-year-old male patient with initially unresectable intrahepatic cholangiocarcinoma of the right liver lobe with tumor thrombi extending from the right bile duct to the common and left bile ducts. Conventional chemotherapy with gemcitabine and cisplatin for 19months resulted in progressive disease. Subsequently, a comprehensive genome profile revealed fibroblast growth factor receptor 2 rearrangement, and hence, pemigatinib administration was initiated. After 6months of pemigatinib therapy, significant shrinking of the tumor and disappearance of the tumor thrombi in the common and left bile duct were observed. Subsequently, the patient underwent conversion surgery, resulting in successful radical resection of the tumor. The patient has been disease-free for 7months.

Fibroblast growth factor receptor signaling in estrogen receptor-positive breast cancer: mechanisms and role in endocrine resistance

Fibroblast Growth Factor Receptors (FGFRs) play a significant role in Estrogen Receptor-positive (ER+) breast cancer by contributing to tumorigenesis and endocrine resistance. This review explores the structure, signaling pathways, and implications of FGFRs, particularly FGFR1, FGFR2, FGFR3, and FGFR4, in ER+ breast cancer. FGFR1 is frequently amplified, especially in aggressive Luminal B-like tumors, and its amplification is associated with poor prognosis and treatment resistance. The co-amplification of FGFR1 with oncogenes like EIF4EBP1 and NSD3 complicates its role as a standalone oncogenic driver. FGFR2 amplification, though less common, is critical in hormone receptor regulation, driving proliferation and treatment resistance. FGFR3 and FGFR4 also contribute to endocrine resistance through various mechanisms, including the activation of alternate signaling pathways like PI3K/AKT/mTOR and RAS/RAF/MEK/ERK. Endocrine resistance remains a major clinical challenge, with around 70% of breast cancers initially hormone receptor positive. Despite the success of CDK 4/6 inhibitors in combination with endocrine therapy (ET), resistance often develops, necessitating new treatment strategies. FGFR inhibitors have shown potential in preclinical studies, but clinical trials have yielded limited success due to off-target toxicities and lack of predictive biomarkers. Current clinical trials, including those evaluating FGFR inhibitors like erdafitinib, lucitanib, and dovitinib, have demonstrated mixed outcomes, underscoring the complexity of FGFR signaling in breast cancer. The interplay between FGFR and other signaling pathways highlights the need for comprehensive molecular profiling and personalized treatment approaches. Future research should focus on identifying robust biomarkers and developing combination therapies to enhance the efficacy of FGFR-targeted treatments. In conclusion, targeting FGFR signaling in ER+ breast cancer presents both challenges and opportunities. A deeper understanding of the molecular mechanisms and resistance pathways is crucial for the successful integration of FGFR inhibitors into clinical practice, aiming to improve outcomes for patients with endocrine-resistant breast cancer.

Fibroblast growth factor receptor signaling in estrogen receptor-positive breast cancer: mechanisms and role in endocrine resistance.

Fibroblast Growth Factor Receptors (FGFRs) play a significant role in Estrogen Receptor-positive (ER+) breast cancer by contributing to tumorigenesis and endocrine resistance. This review explores the structure, signaling pathways, and implications of FGFRs, particularly FGFR1, FGFR2, FGFR3, and FGFR4, in ER+ breast cancer. FGFR1 is frequently amplified, especially in aggressive Luminal B-like tumors, and its amplification is associated with poor prognosis and treatment resistance. The co-amplification of FGFR1 with oncogenes like EIF4EBP1 and NSD3 complicates its role as a standalone oncogenic driver. FGFR2 amplification, though less common, is critical in hormone receptor regulation, driving proliferation and treatment resistance. FGFR3 and FGFR4 also contribute to endocrine resistance through various mechanisms, including the activation of alternate signaling pathways like PI3K/AKT/mTOR and RAS/RAF/MEK/ERK. Endocrine resistance remains a major clinical challenge, with around 70% of breast cancers initially hormone receptor positive. Despite the success of CDK 4/6 inhibitors in combination with endocrine therapy (ET), resistance often develops, necessitating new treatment strategies. FGFR inhibitors have shown potential in preclinical studies, but clinical trials have yielded limited success due to off-target toxicities and lack of predictive biomarkers. Current clinical trials, including those evaluating FGFR inhibitors like erdafitinib, lucitanib, and dovitinib, have demonstrated mixed outcomes, underscoring the complexity of FGFR signaling in breast cancer. The interplay between FGFR and other signaling pathways highlights the need for comprehensive molecular profiling and personalized treatment approaches. Future research should focus on identifying robust biomarkers and developing combination therapies to enhance the efficacy of FGFR-targeted treatments. In conclusion, targeting FGFR signaling in ER+ breast cancer presents both challenges and opportunities. A deeper understanding of the molecular mechanisms and resistance pathways is crucial for the successful integration of FGFR inhibitors into clinical practice, aiming to improve outcomes for patients with endocrine-resistant breast cancer.

Antibody-Drug Conjugates in Urothelial Cancer: From Scientific Rationale to Clinical Development.

Antibody-drug conjugates (ADCs) have been a significant advancement in cancer therapy, particularly for urothelial cancer (UC). These innovative treatments, originally developed for hematological malignancies, use target-specific monoclonal antibodies linked to potent cytotoxic agents. This rational drug design efficiently delivers cancer cell-killing agents to cells expressing specific surface proteins, which are abundant in UC owing to their high antigen expression. UC is an ideal candidate for ADC therapy, as it enhances on-target efficacy while mitigating systemic toxicity. In recent years, considerable progress has been made in understanding the biology and mechanisms of tumor progression in UC. However, despite the introduction of immune checkpoint inhibitors, advanced UC is characterized by rapid progression and poor survival rates. Targeted therapies that have been developed include the anti-nectin 4 ADC enfortumab vedotin and the fibroblast growth factor receptor inhibitor erdafitinib. Enfortumab vedotin has shown efficacy in prospective studies in patients with advanced UC, alone and in combination with pembrolizumab. The anti-Trop-2 ADC sacituzumab govitecan has also demonstrated effectiveness in single-armed studies. This review highlights the mechanism of action of ADCs, their application in mono- and combination therapies, primary mechanisms of resistance, and future perspectives for their clinical use in UC treatment. ADCs have proven to be an increasingly vital component of the therapeutic landscape for urothelial carcinoma, filling a gap in the treatment of this progressive disease.

Synthesis and Biological Evaluation of Thiazole-Based Fibroblast Growth Factor Receptor-1 Inhibitors.

The Fibroblast Growth Factor Receptor-1 (FGFR-1) is a tyrosine kinase and a validated target for the treatment of different cancer types. Design and synthesis of novel thiazole-based analogues of anticancer agents. Series of 2-aryl-5-methylthiazole analogues linked to structurally variable basic heads were synthesized as novel anticancer agents. Developed compounds were tested for their cytotoxic activities against several cancer cell lines. Many analogues exhibited strong antiproliferative activities against breast cancer cell lines, with higher potency towards the highly metastatic form (MDA-MB-231). Pharmacophoric profiling using an in-house pharmacophore database identified FGFR-1 as a molecular target of active analogues. Synthesized compounds were bio-assayed for their FGFR-1 inhibitory activities and many hits exhibited IC50 values in the low micromolar to nanomolar range The 2-aryl-5-methylthiazole linked to a basic head is a novel chemical scaffold of ATP-competitive inhibitor of FGFR-1 with potential therapeutic activities against different types of cancer.

A selective Fibroblast Growth Factor Receptor 1/2 PROTAC degrader with antitumor activity.

The aberrant activation of fibroblast growth factor receptor (FGFR) acts as a potent driver of multiple types of human cancers. Despite the development of several conventional small-molecular FGFR inhibitors, their clinical efficacy is largely compromised due to low selectivity and side effects. Here, we report the selective FGFR1/2-targeting proteolysis targeting chimeric (PROTAC), BR-cpd7 that displays significant isoform specificity to FGFR1/2 with DC50 values around 10 nM, while sparing FGFR3. The following mechanistic investigation reveals the reduced FGFR signaling, through which BR-cpd7 induces cell cycle arrest and consequently blocks the proliferation of multiple FGFR1/2-dependent tumor cells. Importantly, BR-cpd7 has almost no anti-proliferative activity against cancer cells without FGFR aberrations, furtherly supporting its selectivity. In vivo, BR-cpd7 exhibits robust antitumor effects in FGFR1-dependent lung cancer at well-tolerated dose schedules, accompanied by complete FGFR1 depletion. Overall, we identify BR-cpd7 as a promising candidate for developing a selective FGFR1/2-targeted agent, thereby offering a new therapeutic strategy for human cancers in which FGFR1/2 plays a critical role.

Macrophage-derived FGFR1 drives atherosclerosis through PLCγ-mediated activation of NF-κB inflammatory signaling pathway.

Atherosclerosis is a leading cause of cardiovascular morbidity and mortality. Atherosclerotic lesions show increased levels of proteins associated with the fibroblast growth factor receptor (FGFR) pathway. However, the functional significance and mechanisms governed by FGFR signaling in atherosclerosis are not known. In the present study, we investigated FGFR1 signaling in atherosclerosis development and progression. Examination of human atherosclerotic lesions and aortas of Apoe-/- mice fed a high-fat diet (HFD) showed increased levels of FGFR1 in macrophages. We deleted myeloid-expressed Fgfr1 in Apoe-/- mice and showed that Fgfr1 deficiency reduces atherosclerotic lesions and lipid accumulations in both male and female mice upon HFD feeding. These protective effects of myeloid Fgfr1 deficiency were also observed when mice with intact FGFR1 were treated with FGFR inhibitor AZD4547. To understand the mechanistic basis of this protection, we harvested macrophages from mice and show that FGFR1 is required for macrophage inflammatory responses and uptake of oxidized LDL. RNA sequencing showed that FGFR1 activity is mediated through phospholipase-C-gamma (PLCγ) and the activation of nuclear factor-κB (NF-κB) but is independent of FGFR substrate 2. Our study provides evidence of a new FGFR1-PLCγ- NF-κB axis in macrophages in inflammatory atherosclerosis, supporting FGFR1 as a potentially therapeutic target for atherosclerosis-related diseases.

Design, synthesis and antitumor activity of a novel FGFR2-selective degrader to overcome resistance of the FGFR2V564F gatekeeper mutation based on a pan-FGFR inhibitor

Aberrant activation of fibroblast growth factor receptors (FGFRs) contributes to the development and progression of multiple types of cancer. Although many FGFR inhibitors have been approved by the FDA, their long-term therapeutic efficacy is hampered by acquired resistance to gatekeeper mutations and low subtype selectivity. FGFR2 has been found to be frequently amplified or mutated in many tumors. In this study, we designed several PROTACs with different E3 ligands based on LY2874455. By screening the length of the linker and the binding site in various degraders, we obtained a novel and highly efficient FGFR2-selective degrader 28e (DC50 = 0.645 nM, DCmax = 86 %). Compound 28e selectively degraded FGFR2 and essentially avoided degradation of FGFR1,3,4 isoforms (DC50 > 300 nM). Compound 28e significantly inhibited the proliferation of FGFR2-overexpressing cell lines, including KATOIII, SNU16, and AN3CA (IC50 = 0.794 nM/0.207 nM/4.626 nM), comparable to parental inhibitors. At the same time, the preferred compound showed superiority over the parental inhibitor in kinase inhibitory activity against the gatekeeper mutant isoform FGFR2V564F (IC50 = 0.121 nM). In summary, we identified 28e as a novel selective degrader of FGFR2 with high potency and high potential to overcome resistance to gatekeeper mutation. The discovery of 28e provides new evidence for the strategy of pan-inhibitor-based development of selective degrading agents.

SOGUG-NEOWIN: A phase 2, open-label, multi-centre, multi-national interventional trial evaluating the efficacy and safety of erdafitinib (ERDA) monotherapy and ERDA and cetrelimab (CET) as neoadjuvant treatment in patients with cisplatin-ineligible muscle-invasive bladder cancer (MIBC) whose tumours express FGFR gene alterations.

TPS4623 Background: The standard treatment for nonmetastatic MIBC is neoadjuvant cisplatin-based therapy followed by radical cystectomy (RC). However, many patients are ineligible for cisplatin. Immune checkpoint inhibitors (ICIs) have changed the treatment landscape for metastatic urothelial cancer (mUC), including for cisplatin-ineligible patients. Based on these results, ICIs are being explored as neoadjuvant treatment in resectable UC with preliminary data suggesting antitumour activity. ERDA is a Fibroblast Growth Factor Receptor (FGFR) inhibitor, which has shown efficacy in advanced UC with select FGFR2/3 mutations/fusions. ERDA plus cetrelimab demonstrated clinically meaningful activity in patients with newly diagnosed FGFR-altered mUC in the phase 2 NORSE trial. We hypothesize that ERDA plus cetrelimab will improve the pathological complete response (pCR) rate in patients with FGFR+ MIBC who are candidates for RC and are ineligible for or refuse neoadjuvant cisplatin-based therapy. Methods: SOGUG-NEOWIN is a prospective, non-comparative, open label, multicentre, international trial to assess the efficacy of 9 or 12 weeks of neoadjuvant ERDA (cohort 1) or the combination of cetrelimab and ERDA (cohort 2) in patients with MIBC (cT2-Ta N0/1 M0) and FGFR alterations. Key eligibility criteria include ECOG PS 0-1; pure or predominant UC histology; decline or ineligible for cisplatin-based chemotherapy as defined by one of the following criteria: impaired renal function (GFR < 60 mL/min), ≥ grade 2 hearing loss, or ≥ grade 2 peripheral neuropathy; patients are considered fit for cystectomy; no prior FGFR-targeted or anti-PD-(L)1 therapy; no prior systemic therapy, radiation or surgery (except TURBT or biopsies) for bladder cancer; prior BCG was allowed if completed ≥ 6 weeks before initiation of study treatment; no current retinopathy. A total of 45 patients will be allocated to each cohort by a centralized system. Co-primary endpoints are pCR rate and percentage of pathological downstaging response (<ypT2). Secondary endpoints include event-free survival, overall survival, overall response rate, safety, tolerability, and delay to surgery. Biomarkers of response and resistance will be assessed using baseline archival tissues, blood and urine. Quality of life (QoL) will be assessed using FACT-Bl and EQ-5D-5L. Tumour response assessment via PET-MRI will be performed in a subset of patients. The trial is approved in 4 countries. The first patient was included on 31-Jan-2024. This trial would be the first to systematically address whether ERDA ± cetrelimab improves pCR in patients with FGFR-positive MIBC. (EudraCT 2022-002586-15). Clinical trial information: 2022-002586-15.

Antitumor Activity of Tasurgratinib as an Orally Available FGFR1-3 Inhibitor in Cholangiocarcinoma Models With FGFR2-fusion.

Cholangiocarcinoma (CCA) is an aggressive tumor with limited treatment options especially in 2nd line or later treatments. Targeting fibroblast growth factor receptor (FGFR) 2 has recently emerged as a promising treatment option for patients with CCA harboring FGFR2-fusion. This study investigated the antitumor activities of tasurgratinib as an orally available FGFR1-3 inhibitor, in preclinical FGFR2-driven CCA models. Antitumor activities of tasurgratinib were examined in vitro and in vivo using NIH/3T3 cells expressing FGFR2-fusion as FGFR2-driven CCA models, and in vivo using a CCA patient-derived xenograft model. The molecular mechanism of action of tasurgratinib was elucidated through co-crystal structure analysis with FGFR1, manual complex model analysis with FGFR2, and binding kinetics analysis with FGFR2. Furthermore, the cell-based inhibitory activities against acquired resistant FGFR2 mutations in patients with CCA treated with FGFR inhibitors were evaluated. Tasurgratinib showed antitumor activity in preclinical FGFR2-driven CCA models by inhibiting the FGFR signaling pathway in vitro and in vivo. Furthermore, cell-based target engagement assays indicated that tasurgratinib had potent inhibitory activities against FGFR2 mutations, such as N549H/K, which are the major acquired mutations in CCA. We also confirmed that tasurgratinib exhibited fast association and slow dissociation kinetics with FGFR2, binding to the ATP-binding site and the neighboring region, and adopting an Asp-Phe-Gly (DFG)-"in" conformation. These data demonstrate the therapeutic potential of tasurgratinib in FGFR2-driven CCA and provide molecular mechanistic insights into its unique inhibitory profile against secondary FGFR2 resistance mutations in patients with CCA treated with FGFR inhibitors.

Abstract B014: FGFR inhibition upregulates Nectin-4 expression in FGFR3 altered urothelial carcinoma

Abstract Bladder urothelial carcinoma (UC) is a common malignancy and remains a significant cause of mortality; however, in recent years there have been substantial advances in the treatment of metastatic UC (mUC). This includes the approval of the antibody drug conjugate (ADC) enfortumab vedotin, which targets Nectin-4, and the fibroblast growth factor receptor (FGFR) inhibitor erdafitinib (in FGFR2/3 altered tumors). Despite the impressive efficacy of these agents, most patients will ultimately develop progressive disease, underlining the need for further therapeutic development. Previous work has demonstrated that NECTIN4 expression and FGFR3 alterations are enriched in luminal subtypes of UC and NECTIN4 expression is higher in FGFR altered tumors. We validate these findings in scRNAseq from primary tumors as well as bulk RNAseq from murine models. Given the positive correlation between NECTIN4 and FGFR3 alterations we hypothesized that FGFR3 inhibition would downregulate Nectin-4 expression. To our surprise we found in vitro treatment with erdafitinib in cell lines with FGFR3 fusion proteins (RT112, RT4, SW780) lead to an increase in Nectin-4 protein levels. Additionally, in vitro FGFR inhibition in the UMUC-14 cell line which harbors an FGFR3S249C hotspot mutation, upregulates Nectin-4 protein levels. To further investigate this phenomenon, we engineered the FGFR3 WT cell line, 5637 to overexpress FGFR3-TACC3 or FGFR3S249C. We saw that FGFR3-TACC3 and FGFR3S249C overexpression both down regulated Nectin-4 indicating that FGFR3 activity negatively regulates Nectin-4 expression. We have also investigated the association between FGFR inhibition and Nectin-4 expression in two in vivo models: (1) in a xenograft model using the RT112 line we found an overall increase in Nectin-4 expression in tumors treated with a 5-day course of erdafitinib; (2) in a UPFL1 (a cell line derived from a genetically engineered mouse with a S249C mutation) syngeneic model we also saw an increase in Nectin-4 expression after erdafitinib treatment. We have observed that the increase in Nectin-4 expression persists in vitro even after withdrawal of erdafitinib treatment, indicating that intermittent dosing of erdafitinib maybe be sufficient to prime a tumor for Nectin-4 targeted therapy. Lastly, preliminary in vitro investigation of the combination of erdafitinib and enfortumab vedotin in RT112 cells showed synergy, particularly with lower doses of both agents, providing further support of our hypothesis that FGFR3 inhibition may act to sensitize UC to Nectin-4 ADC therapy. A potential synergistic relationship is further supported by the recent results of the phase 1 trial investigating the combination of erdafitinib plus enfortumab vedotin in which the objective response rate was 100% (9/9 patients: 8 PRs & 1CR). Citation Format: Sean Clark-Garvey, Mi Zhou, Michael Sturdivant, Wolfgang Beckabir, Lucia Kim, E. Drew Toomer, Ian McCabe, Akihiro Hamada, Daniel Crona, Jeffrey S. Damrauer, William Y. Kim. FGFR inhibition upregulates Nectin-4 expression in FGFR3 altered urothelial carcinoma [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr B014.

Genomic medicine advances for brain tumors.

Cancer genome profiling has revealed important genetic alterations that serve as prognostic indicators and guides for treatment decisions, enabling precision medicine. The shift to molecular diagnosis of brain tumors, as reflected in the 2021 World Health Organization Classification of Tumors of the Central Nervous System, is a crucial role for treatment decision-making. This review discusses the significance and role of cancer genome profiling in precision medicine for malignant brain tumors, particularly gliomas. Furthermore, we explore the progress in cancer genome analysis, focusing on cancer gene panel testing, integration of genomic information in brain tumor classification, and hereditary tumors. Additionally, we discuss the transformative effect of genomic medicine on early detection, risk assessment, and precision medicine strategies. The tumor mutational burden in brain tumors is considered low, but the application of molecular targeted drugs, such as isocitrate dehydrogenase inhibitors, v-raf murine sarcoma viral oncogene homolog B1 inhibitors, fibroblast growth factor receptor inhibitors, neurotrophic tyrosine receptor kinase, mechanistic target of rapamycin inhibitors, and anti-programmed death receptor-1 antibody drugs are promising for glioma treatment. We also discuss the future prospects of molecular targeted drugs.

Discovery of 2,6-Naphthyridine Analogues as Selective FGFR4 Inhibitors for Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the most common type of liver cancer and is responsible for 90% of cases. Approximately 30% of patients diagnosed with HCC are identified as displaying an aberrant expression of fibroblast growth factor 19 (FGF19)-fibroblast growth factor receptor 4 (FGFR4) as an oncogenic-driver pathway. Therefore, the control of the FGF19-FGFR4 signaling pathway with selective FGFR4 inhibitors can be a promising therapy for the treatment of HCC. We herein disclose the design and synthesis of novel FGFR4 inhibitors containing a 2,6-naphthyridine scaffold. Compound 11 displayed a nanomolar potency against Huh7 cell lines and high selectivity over FGFR1-3 that were comparable to that of fisogatinib (8) as a reference standard. Additionally, compound 11 demonstrated remarkable antitumor efficacy in the Huh7 and Hep3B HCC xenograft mouse model. Moreover, bioluminescence imaging experiments with the orthotopic mouse model support that compound 11 can be considered a promising candidate for treating HCC.

Pemigatinib in previously treated solid tumors with activating FGFR1-FGFR3 alterations: phase 2 FIGHT-207 basket trial.

Fibroblast growth factor receptor (FGFR) alterations drive oncogenesis in multiple tumor types. Here we studied pemigatinib, a selective, potent, oral FGFR1-FGFR3 inhibitor, in the phase 2 FIGHT-207 basket study of FGFR-altered advanced solid tumors. Primary end points were objective response rate (ORR) in cohorts A (fusions/rearrangements, n = 49) and B (activating non-kinase domain mutations, n = 32). Secondary end points were progression-free survival, duration of response and overall survival in cohorts A and B, and safety. Exploratory end points included ORR of cohort C (kinase domain mutations, potentially pathogenic variants of unknown significance, n = 26) and analysis of co-alterations associated with resistance and response. ORRs for cohorts A, B and C were 26.5% (13/49), 9.4% (3/32) and 3.8% (1/26), respectively. Tumors with no approved FGFR inhibitors or those with alterations not previously confirmed to be sensitive to FGFR inhibition had objective responses. In cohorts A and B, the median progression-free survival was 4.5 and 3.7 months, median duration of response was 7.8 and 6.9 months and median overall survival was 17.5 and 11.4 months, respectively. Safety was consistent with previous reports. The most common any-grade treatment-emergent adverse events were hyperphosphatemia (84%) and stomatitis (53%). TP53 co-mutations were associated with lack of response and BAP1 alterations with higher response rates. FGFR1-FGFR3 gatekeeper and molecular brake mutations led to acquired resistance. New therapeutic areas for FGFR inhibition and drug failure mechanisms were identified across tumor types. ClinicalTrials.gov identifier: NCT03822117 .

Discovery of LHQ490 as a highly selective fibroblast growth factor receptor 2 (FGFR2) inhibitor

Fibroblast growth factor receptor 2 (FGFR2) represents an appealing therapeutic target for multiple cancers, yet no selective FGFR2 inhibitors have been approved for clinical use to date. Here, we report the discovery of a series of new selective, irreversible FGFR2 inhibitors. The representative compound LHQ490 potently inhibited FGFR2 kinase activity with an IC50 of 5.2 nM, and was >61-, >34-, and >293-fold selective against FGFR1, FGFR3, and FGFR4, respectively. LHQ490 also exhibited high selectivity in a panel of 416 kinases. Cell-based studies revealed that LHQ490 efficiently suppressed the proliferation of BaF3-FGFR2 cells with an IC50 value of 1.4 nM, and displayed >70- and >714-fold selectivity against BaF3-FGFR1 and the parental BaF3 cells, respectively. More importantly, LHQ490 potently suppressed the FGFR2 signaling pathways, selectively inhibited FGFR2-driven cancer cell proliferation, and induced apoptosis of FGFR2-driven cancer cells. Taken together, this study provides a potent and highly selective FGFR2 inhibitor for further development of FGFR2-targeted therapeutic agents.

The evolving treatment landscape of metastatic urothelial cancer.

Cisplatin-based chemotherapy is currently the first-line standard of care for patients with metastatic urothelial cancer (mUC); however, up to 50% of patients are ineligible for cisplatin, necessitating alternative treatment options. Immune checkpoint inhibitors have been shown to be effective in cisplatin-ineligible patients. However, despite advances in the first-line setting, the prognosis remains poor, and challenges persist in selecting optimal therapies, treatment sequences and combination regimens. Maintenance therapy with avelumab revealed improved overall (OS) and progression-free survival (PFS) compared with best supportive care alone in patients with platinum-responsive mUC. Antibody-drug conjugates and targeted therapy with fibroblast growth factor receptor (FGFR) inhibitors have shown promise in selected patients, particularly in patients with metastatic disease that has progressed despite platinum-based chemotherapy. At the European Society of Medical Oncology Congress in 2023, groundbreaking results were presented from two phase III trials, EV-302/KEYNOTE-A39 and CheckMate 901, focusing on previously untreated mUC. In the former, the combination of enfortumab vedotin and pembrolizumab showed significant improvements in OS, PFS and overall response rate compared with chemotherapy alone; the combination of nivolumab with gemcitabine-cisplatin chemotherapy demonstrated a significant extension in median OS, PFS and overall response rate compared with chemotherapy alone. Inaddition, erdafitinib therapy resulted in significantly longer OS than chemotherapy among patients with mUC and FGFR alterations after previous treatment with immune checkpoint inhibitors. This comprehensive summary of the current treatment landscape for mUC incorporates clinical trial evidence and discussion of agents that are currently under investigation to provide support for clinical decision making and understanding of future therapeutic approaches.

Abstract PO3-18-08: Rational therapeutic combination of Bromodomain and Extra-Terminal domain (BET) inhibitor and Fibroblast Growth Factor Receptor (FGFR) inhibitor for treatment of invasive lobular carcinoma

Abstract Background: Invasive lobular carcinoma (ILC) is the second most pervasive subtype after invasive ductal carcinoma (IDC), accounting for approximately 10-15% of all breast cancers. It is characterized by loss of E-cadherin expression and non-adherent tumor cells that invade the stroma in a “single-file” pattern. Women with ILC are typically diagnosed at an older age and later stage with ER-positive disease. ILC is more likely to exhibit late recurrence and metastasize to the gastrointestinal tract and urogenital tract compared with IDC. It is routinely treated with anti-endocrine therapy and chemotherapy, however, while not entirely chemo-refractory, displays a poor response to chemotherapy compared with IDC. As such, options for recurrent disease are limited and there is an urgent need to develop tailored therapy for ILC, especially for those patients that recur. The family of bromodomain and extra-terminal domain (BET) proteins, comprising BRD2/3/4/T, are epigenetic readers that bind to acetylated lysine residues on histones and recruit transcription factors to drive the expression of oncogenes. Previously. we discovered that BRD3 is a marker of poor prognosis in ILC and there is emerging evidence that BET inhibitors (iBET) are effective in diverse types of breast cancer. Here, we investigated the therapeutic potential of iBET in ILC, alone and in combination with FGFR inhibitors. Methods: IC50s for a panel of iBET using two typical ILC cell lines MDA-MB-134VI (MM134) and SUM44PE (SUM44) were determined. RNA-sequencing and Genexplain analysis was applied to reveal transcriptional networks, master regulators and potential resistance mechanisms. BRD3 and FGFR3 were knocked down using siRNA to evaluate their function in ILC cell lines. Furthermore, we utilized ILC cell-derived xenograft (CDX) models in SCID-beige mice established by mammary intraductal (MIND) implantation to evaluate the therapeutic potency of iBET alone or in combination with fibroblast growth factor receptor (FGFR) inhibitor in vivo. Results: We demonstrated that iBET significantly inhibited ILC cell growth in both 2D and 3D culture, with the greatest potency demonstrated by JQ1 and Mivebresib (ABBV-075). RNA-sequencing revealed dysregulated pathways in cell cycle division, DNA damage, apoptosis and MAPK signaling following iBET treatment. Reverse engineering of transcriptional profiles using Genexplain revealed that FGFR3 is a significantly upregulated master regulator (MTR) among 142 MTRs across both cell lines and both iBETs. Upregulation of FGFR3 after iBET treatment was verified at the protein level by Western blotting. We also show that BRD3 and FGFR3 knockdown significantly inhibited cell growth, which supports the key role both play in ILC progression. Further, we analyzed the iBET therapeutic effect when combined with the FGFR inhibitor, erdafitinib, as a strategy to overcome potential resistance due to FGFR upregulation post iBET treatment. This revealed that the combination of iBET and erdafitinib could inhibit ILC cell growth more effectively compared to using either agent alone. Furthermore, our in vivo study showed that JQ1 could inhibit tumor growth in a SUM44-MIND model and alleviate metastasis to peritoneum, bone and ovary compared with the vehicle group. Moreover, we also assessed the combination of mivebresib and erdafitinib in vivo. This revealed that iBET and an FGFR inhibitor work synergistically to decrease tumour burden and metastatic potential in both MM134-MIND and SUM44-MIND models. Conclusion: Our results provide evidence that iBET, either alone or in combination with erdafitinib, is remarkably effective at inhibiting ILC growth, both in vitro and in vivo and represents a rational therapeutic strategy for recurrent ILC patients in the future. Citation Format: Binbin Gao, Elspeth Ward, Anna Blümel, Emer Conroy, Rachel Moore, Grainne Cremin, Rachel Bleach, Kathryn Haley, Tríona Ní Chonghaíle, Andreas Lindner, Jochen Prehn, Yi Zhang, Idalia Cruz, Leena Hilakivi-Clarke, Georgios Sflomos, Cathrin Brisken, William Gallagher, Darran O'Connor. Rational therapeutic combination of Bromodomain and Extra-Terminal domain (BET) inhibitor and Fibroblast Growth Factor Receptor (FGFR) inhibitor for treatment of invasive lobular carcinoma [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-18-08.