Mutations In Fibroblast Growth Factor Receptor Research Articles

FGFR3 Mutational Activation Can Induce Luminal-like Papillary Bladder Tumor Formation and Favors a Male Sex Bias

BackgroundBladder cancer (BCa) is more common in men and presents differences in molecular subtypes based on sex. Fibroblast growth factor receptor 3 (FGFR3) mutations are enriched in the luminal papillary muscle-invasive BCa (MIBC) and non-MIBC subtypes. ObjectiveTo determine whether FGFR3 mutations initiate BCa and impact BCa male sex bias. Design, setting, and participantsWe developed a transgenic mouse model expressing the most frequent FGFR3 mutation, FGFR3-S249C, in urothelial cells. Bladder tumorigenesis was monitored in transgenic mice, with and without carcinogen exposure. Mouse and human BCa transcriptomic data were compared. InterventionMutant FGFR3 overexpression in mouse urothelium and siRNA knockdown in cell lines, and N-butyl-N(4-hydroxybutyl)-nitrosamine (BBN) exposure. Outcome measurements and statistical analysisImpact of transgene dosage on tumor frequency, synergy with BBN treatment, and FGFR3 pathway activation were analyzed. The sex-specific incidence of FGFR3-mutated tumors was evaluated in mice and humans. FGFR3 expression in FGFR3-S249C mouse urothelium and in various human epithelia was measured. Mutant FGFR3 regulation of androgen (AR) and estrogen (ESR1) receptor activity was evaluated, through target gene expression (regulon) and reporter assays. Results and limitationsFGFR3-S249C expression in mice induced low-grade papillary BCa resembling human luminal counterpart at histological, genomic, and transcriptomic levels, and promoted BBN-induced basal BCa formation. Mutant FGFR3 expression levels impacted tumor incidence in mice, and mutant FGFR3–driven human tumors were restricted to epithelia presenting high normal FGFR3 expression levels. BCa male sex bias, also found in our model, was even higher in human FGFR3-mutated tumors compared with wild-type tumors and was associated with higher AR and lower ESR1 regulon activity. Mutant FGFR3 expression inhibited both ESR1 and AR activity in mouse tumors and human cell lines, demonstrating causation only between FGFR3 activation and low ESR1 activity in tumors. ConclusionsMutant FGFR3 initiates luminal papillary BCa formation and favors BCa male sex bias, potentially through FGFR3-dependent ESR1 downregulation. Patients with premalignant lesions or early-stage BCa could thus potentially benefit from FGFR3 targeting. FGFR3 expression level in epithelia could account for FGFR3-driven carcinoma tissue specificity. Patient summaryBy developing a transgenic mouse model, we showed that gain-of-function mutations of FGFR3 receptor, among the most frequent genetic alterations in bladder cancer (BCa), initiate BCa formation. Our results could support noninvasive detection of FGFR3 mutations and FGFR3 targeting in early-stage bladder lesions.

Role of Fibroblast Growth Factors in the Crosstalk of Hepatic Stellate Cells and Uveal Melanoma Cells in the Liver Metastatic Niche.

Hepatic metastasis is the critical factor determining tumor-associated mortality in different types of cancer. This is particularly true for uveal melanoma (UM), which almost exclusively metastasizes to the liver. Hepatic stellate cells (HSCs) are the precursors of tumor-associated fibroblasts and support the growth of metastases. However, the underlying mechanisms are widely unknown. Fibroblast growth factor (FGF) signaling is dysregulated in many types of cancer. The aim of this study was to analyze the pro-tumorigenic effects of HSCs on UM cells and the role of FGFs in this crosstalk. Conditioned medium (CM) from activated human HSCs significantly induced proliferation together with enhanced ERK and JNK activation in UM cells. An in silico database analysis revealed that there are almost no mutations of FGF receptors (FGFR) in UM. However, a high FGFR expression was found to be associated with poor survival for UM patients. In vitro, the pro-tumorigenic effects of HSC-CM on UM cells were abrogated by a pharmacological inhibitor (BGJ398) of FGFR1/2/3. The expression analysis revealed that the majority of paracrine FGFs are expressed by HSCs, but not by UM cells, including FGF9. Furthermore, the immunofluorescence analysis indicated HSCs as a cellular source of FGF9 in hepatic metastases of UM patients. Treatment with recombinant FGF9 significantly enhanced the proliferation of UM cells, and this effect was efficiently blocked by the FGFR1/2/3 inhibitor BGJ398. Our study indicates that FGF9 released by HSCs promotes the tumorigenicity of UM cells, and thus suggests FGF9 as a promising therapeutic target in hepatic metastasis.

Characterization of the cholangiocarcinoma drug pemigatinib against FGFR gatekeeper mutants

Fibroblast growth factor receptor (FGFR) dysregulation is involved in a variety of tumorigenesis and development. Cholangiocarcinoma is closely related with FGFR aberrations, and pemigatinib is the first drug approved to target FGFR for the treatment of cholangiocarcinoma. Herein, we undertake biochemical and structural analysis on pemigatinib against FGFRs as well as gatekeeper mutations. The results show that pemigatinib is a potent and selective FGFR1–3 inhibitor. The extensive network of hydrogen bonds and van der Waals contacts found in the FGFR1-pemigatinib binding mode accounts for the high potency. Pemigatinib also has excellent potency against the Val-to-Ile gatekeeper mutation but less potency against the Val-to-Met/Phe gatekeeper mutation in FGFR. Taken together, the inhibitory and structural profiles exemplified by pemigatinib may help to thwart Val-to-Ile gatekeeper mutation-based resistance at earlier administration and to advance the further design and improvement for inhibitors toward FGFRs with gatekeeper mutations.

Anlotinib Combined with Toripalimab as Second-Line Therapy for Advanced, Relapsed Gastric or Gastroesophageal Junction Carcinoma.

Our study aimed to explore the efficacy and safety of anlotinib-toripalimab combination therapy as a second-line treatment for advanced relapsed gastric or gastroesophageal junction carcinoma (GC/GEJC). In this single arm, single-center extension clinical trial, patients with advanced relapsed GC/GEJC received toripalimab (240 mg, intravenously over 60 minutes, once every 2 weeks) plus anlotinib (12 mg/day, orally, 2 weeks on and 1 week off, every 3 weeks) as second-line therapy. There were 29 patients who achieved partial response, and the ORR was 32.3% (95% CI, 26.6%-38.5%). Grade 3 treatment-related adverse events (TRAEs) were recorded in 7 participants (11.3%), all of which were manageable. The PFS and OS were 4.0 and 11.1 months, respectively. Patients with programmed death-ligand 1 (PD-L1) positive expression showed numerically longer OS than the negative ones although the difference was not significantly. The tumor mutational burden-high (TMB-H) group showed a significantly better OS (P = .05) than the TMB-Low (TMB-L) group. Next-generation sequencing (NGS) revealed that fibroblast growth factor receptor 2 (FGFR2) mutations positively correlated with target lesion reduction (odds ratio [OR] = 0.14; P = .02). The new regimen increased tumor-infiltration of CD8+ T and CD3+ T cells. Furthermore, a patient-derived organoid (PDO) study indicated that anlotinib could promote an immune-supportive tumor microenvironment. As conclusion, the anlotinib-toripalimab combination showed promising efficacy and favorable safety as a second-line treatment for advanced, relapsed GC/GEJC. The PD-L1 expression, TMB, and FGFR2 mutation are potential biomarkers for predicting the efficacy of this regimen (ClinicalTrials.gov registration number: NCT04713059).

Abstract 167: Pre-clinical characterization of a novel series of FGFR2 selective inhibitors with potency against clinically relevant mutations

Abstract The fibroblast growth factor receptor (FGFR) family of protein tyrosine kinases plays a role in many physiological processes including angiogenesis and wound healing. FGFR mutations, fusions, rearrangements, and amplifications have been linked to the pathogenesis of multiple tumor types. For example, approximately 10-15% of patients with intrahepatic cholangiocarcinoma have FGFR2 fusions, and amplification of FGFR2 is prevalent in gastric cancer and implicated in tumor growth. Approved FGFR inhibitors produce responses in patients that harbor FGFR genetic alterations but show reduced activity against key mutations (e.g., V565, N550, etc.). These pan-FGFR inhibitors also frequently show dose-limiting toxicities including hyperphosphatemia which can be linked to the inhibition of FGFR1. To address these issues, a novel series of FGFR inhibitors that are potent and selective reversible inhibitors of FGFR2 with selectivity over FGFR1 have been identified. This series also maintains activity against clinically relevant mutations in the FGFR2 protein. Inhibition of cellular FGFR phosphorylation was measured using engineered cell lines to demonstrate that the inhibitors target both wild-type FGFR2 and activating FGFR2 mutations while sparing FGFR1. In addition, CDX tumor models showed in vivo target engagement and FGFR isoform selectivity. Herein, the in vitro and in vivo characterization of a representative selective reversible FGFR2 inhibitor is described. Citation Format: John Fischer, Karyn Bouhana, Mark J. Chicarelli, Josh Dahlke, Brad Fell, Jennifer Fulton, Anna Guarnieri, Ravi Jalluri, Amber Johnson, Brent Mclean, Max Mejia, Rob Rieger, John Robinson, Mareli Rodriguez, Francis Sullivan, Yang Wang, Shannon Winski, Yeyun Zhou. Pre-clinical characterization of a novel series of FGFR2 selective inhibitors with potency against clinically relevant mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 167.

Comprehensive analysis of FGFR mutations in Chinese cancer patients.

e15117 Background: Fibroblast growth factor receptors (FGFRs) are highly conserved transmembrane tyrosine kinase receptors (RTKS) that regulating several cellular processes such as proliferation, differentiation, migration and survival. In recent years, some studies have documented that signaling through FGFRs impact progression of cancer and the survival of patients with cancer. As a potential therapeutic target, exploring the mutation frequency of FGFRs in more different cancers are necessary. Here we performed a comprehensive analysis of the frequency and types of FGFRs mutations in Chinese cancer patients and provided reference for targeted therapy development. Methods: From January 2020 to December 2021, a total of 4,102 patients with nine common cancers were included in the study. The next-generation sequencing was utilized for detecting genetic mutations. Results: A total 328 patients (7.9%) with FGFR mutation were identified. The FGFR 3 was the most frequently gene in our cohort. Among all the cancer patients, the highest frequency of FGFR mutations was observed in bladder cancer (32.5%) and the percentages in FGFR1, FGFR2 and, FGFR3 were 2.7%, 1.35%, and 6.76% respectively. Furthermore, the proportion of FGFR mutation in lung carcinoma, cholangiocarcinoma, colorectal carcinoma, melanoma, breast carcinoma and ovarian carcinoma was 8.64%, 11.58%, 13%, 16.7%, 9.62% and 10.81% respectively. Additionally, FGFR mutation have been detected in other tumor types, including renal cell carcinoma (5.63%), prostate cancer (5.45%), and gastric carcinoma (13.72%). Conclusions: The present study provided the comprehensive FGFR mutation data of Chinese cancer patients. A high frequency mutation in FGFR have been found in Chinese patients with different cancers, which mean that patients with multiple cancer types might benefit from development of efficient EGFR inhibitors.

In vitro and in vivo investigations of anlotinib in bladder cancer treatment.

e16505 Background: Bladder cancer is one of the most common malignancy in urinary system. Fibroblast growth factor receptor 3 (FGFR3) is the most common alteration gene in bladder cancer, occurring in approximately 70% of non-metastatic bladder cancer and 20% of metastatic bladder cancer. Anlotinib is a potent oral, multi-target tyrosine kinase inhibitor with a favorable safety which mainly targets vascular endothelial growth factor receptor (VEGFR), FGFR, platelet-derived growth factor receptors, and c-kit. This study aims to investigate the role of anlotinib in bladder cancer compared with FGFR3 inhibitor erdafitinib i n vitro and in vivo. Methods: MTT, colony formation, and Transwell assays were performed on bladder cancer cells (SW780 and UMUC14) to confirm the effects of anlotinib and erdafitinib on proliferation, migration and invasion. Apoptotic effect was evaluated by Annexin V/propidium iodide double staining, and the levels of the protein and mRNA were examined by RNA-seq, Western blotting and RT-qPCR. Finally, mice with palpable xenografts were treated either with anlotinib and erdafitinib for 8 days before they were sacrificed for measuring the sizes and weights of the tumors. Results: To assess the roles of anlotinib in bladder cancer, we treated SW780 cell line which had FGFR3-BALAP2L1 fusion mutation and UMUC-14 cell line which had a FGFR3 (MuS247C) mutation with DMSO, anlotinib and erdafitinib. As seen in MTT, colony formation and Transwell assays, anlotinib repressed cell proliferation, migration and invasion as erdafitinib. Compared with vehicle, Anlotinib promoted cell apoptosis of bladder cancer cells. To further explore the mechanism, anlotinib and erdafitinib suppressed p-Erk1/2 and p-AKT, while only anlotinib inhibited the expression of VEGF-a. Compared with erdafitinib, the inhibitory ability of anlotinib was weaker than that of erdafitinib in cell line with FGFR3 (MuS247C) mutation, on the contrary, it was much stronger in cell line with FGFR3-BALAP2L1 fusion mutation. In addition, the in vivo data from xenagrafts also supported that anlotinib could significantly repress tumor growth with FGFR3 fusion mutation, and the efficacy was better than erdafitinib. Conclusions: Anlotinib could repress the proliferation, migration and invasion of bladder cancer cells by inhibiting the phosphorylation of Erk1/2 and AKT, and the suppression VEGF-a expression, whose effects was better than erdafitinib in bladder cancer with FGFR3 fusion mutation. Therefore, anlotinib might be a potential novel targeted agent to treat the bladder cancer patients with FGFR3 fusion mutations, and clinical trials are needed for further investigation.

144-OR: Adipose Modeling of FGF21 Signaling Mutations in a Severe Insulin Resistance Syndrome

Insulin-mediated pseudoacromegaly (IMPA) is a rare, severe insulin resistance syndrome characterized by tall stature, acanthosis nigricans, obesity, and acromegalic features. Patients with IMPA have normal growth hormone and IGF-1. However, they have markedly increased insulin levels. Our group previously described a patient with IMPA who carries digenic mutations in fibroblast growth factor receptor 1 (FGFR1) and beta-klotho (KLB) , which form the receptor complex for FGF21. FGF21 is a hepatokine that plays a critical role in adipose insulin sensitivity. To assess the pathogenicity of these mutations, we isolated iPSC from the proband with IMPA. We used CRISPR gene editing to correct the FGFR1 and KLB mutations and differentiated the iPSC lines into adipocytes. Both the uncorrected (mutant) and corrected (wild-type) lines were able to undergo successful differentiation to adipocytes. Western immunoblotting demonstrated that the uncorrected cells demonstrated decreased levels of FGFR1, pERK1/2, and p38-MAPK in response to insulin and/or FGF21. Additionally, the mutant adipocytes demonstrated significantly larger lipid droplets when stained with BODIPY (mean droplet size 62.6 μm2 uncorrected; 40.8 μm2 corrected; p= 0.00016) . To complement the iPSC work, a transgenic knock-in mouse line was created using CRISPR gene editing. Explants of gonadal white adipose tissue isolated from these mice demonstrated significantly decreased lipolysis (Max NEFA in mutant 0.mEq/L; wild-type 0.13 mEq/L; p=0.003) . Additionally, qRT PCR was performed in brown adipose tissue demonstrating decreased Ucp1 expression (mutant mice 37.2% of WT; p=4.0x10-5) . These results suggest that the FGFR1 and KLB mutations lead to decreased FGF21 signaling. Mutant adipose tissues are dysfunctional with impaired lipolysis and Ucp1 expression. Therefore these models are useful for determining the role of the FGF21 signaling in human insulin resistance syndromes. Disclosure N.Phan: None. D.M.Ornitz: None. S.I.Stone: Speaker's Bureau; Rhythm Pharmaceuticals, Inc. Funding NICHD (R21 HD098872) , NIDDK (KDK124574) , NCATS (UL1TR000448) , NIDDK (P30 DK020579) , NIDDK (P30 DK056341) , Burroughs Wellcome Fund Physician-Scientist Institutional Award, and Centene Precision Medicine Initiative

Molecular mechanism in urothelial carcinoma with FGFR3 mutation.

e16548 Background: Specific genomic alterations in the FGFR (fibroblast growth factor receptor) family are well-known to be characteristic driver events of urothelial carcinoma and is a therapeutic target. However, molecular mechanism differences of urothelial carcinoma (UC) stratified by the FGFR mutation status has not yet been described. Methods: Patients diagnosed with UC were enrolled in the study. Tumor tissue and matching blood were sequenced by next-generation sequencing (NGS) techniques with Acornmed panel with 808 cancer-related genes. Results: A total of 368 patients with UC were enrolled including 75 patients with FGFR2/3 mutation and 293 patients with FGFR2/3 wildtype. In FGFR2/3 mutation cohorts, the five most frequently mutated genes were FGFR2/3 (100%), KMT2D (56%), KMT2C (35%), CREBBP (32%) and FAT1 (31%). For FGFR2/3 wildtype cohorts, the five most frequently mutated genes were TP53 (46%), KMT2D (41%), BRD4 (23%), ARID1A (15%), and KMT2C (14%). 87 frequently mutated genes were significant difference between FGFR2/3 mutation and FGFR2/3 wildtype cohorts, such as KMT2D, KMT2C, STAG2, CREBBP and FAT1, excluding the FGFR2/3 gene. Signature 1 for spontaneous deamination of 5−methylcytosine and signature 22 for exposure to aristolochic acid (AA) existed in both cohorts. Although there were APOBEC Cytidine Deaminase signatures in both groups, they were projected to different COSMIC signatures (signature 2 and 13, respectively). Signature 10 for defects in polymerase POLE (4.81%) were only observed in the FGFR2/3 mutation cohorts. In the FGFR2/3 mutation cohorts, mutated genes were mainly enriched in the cancer pathway, PI3K-Akt signaling pathway, and Ras signaling pathway. However, in the FGFR2/3 wildtype cohorts, the primary pathways included the cancer pathway, PI3K-Akt signaling pathway, and Rap1 signaling pathway. Conclusions: There were characterized the genomic differences and similarities, stratified by the TP53 status, which may reflect the UC patients with TP53 mutation harbored specific molecular mechanism.

Screening of FGFR patients for FGFR directed clinical trials in Network Genomic Medicine (NGM): Real-world data.

e21013 Background: The fibroblast growth factor receptor (FGFR) 1-4 genes show a heterogenic landscape of alterations in non-small cell lung cancer (NSCLC) whereas only a small amount is yet considered to have oncogenic potential. The frequency of activating FGFR alterations is low, counting for approximately 2% of NSCLC. We have screened NSCLC patients (pts) for FGFR translocations/mutations within NGM and analysed them on FGFR alteration frequency, patient characteristics and outcome. Methods: From 04/2019 to 01/2020 we screened 472 squamous NSCLC for FGFR gene alterations and from 02/2020 to 12/2021 an additional 5286 patients including all NSCLC cases. Of these 5286 pts, 1097 pts were analysed for FGFR fusions. We used DNA-NGS for FGFR-mutations and RNA-NGS for FGFR–translocations. Activating mutations were defined according to the publicly available molecular data bases and published data. Results: Within the cohort of 5758 NSCLC patients, we found 316 (5.5%) patients with FGFR alterations. Sixty-six (20.9% of FGFR, 1.1% of NSCLC) patients had alterations classified as activating, of whom 39 had FGFR point mutations and 27 FGFR translocations. Concerning the patients with activating alterations, they had UICC stage III or IV at time of diagnosis; 22 were females; 58 patients had squamous cell carcinoma, 6 patients had adenocarcinoma and 2 had large cell neuroendocrine carcinoma. Fifty-three patients (80.3%) with activating FGFR alteration had a co-mutation: TP53 (inactivating) co-mutation was seen in 41 cases (62.1%) and 19 cases had either PTEN (7 pts), KRAS (4), EGFR (3), PIK3CA (2), ROS1 (1), ALK (1) or BRAF (1) mutations. Ten patients were included in a FGFR-targeted trial. Sixty patients were available for follow-up. The median overall survival (mOS) was 21.4 month (95%CI: 16.8–25.9) for all patients with activating FGFR alteration, whereas mOS was 18.5 month (95%CI: 13.2-23.9) for FGFR mutation and 25.3 months (95%CI: 17.8-32.9) for FGFR fusions. Conclusions: FGFR 1-4 gene alterations are rare. Large molecular and clinical networks are necessary to identify these pts. Prognostic factors of FGFR patients are currently not defined. Further assessments on molecular and clinical features in FGFR altered NSCLC are needed to identify sensitivity to FGFR inhibition. Clinical trials with specific FGFR inhibitors are ongoing.

Meckel’s Cartilage and Mandibles: Effects of the Fgfr2 C342Y mutation on development of the lower jaw in a Crouzon syndrome mouse model

The Fgfr2cC342Y/+ Crouzon syndrome mouse model carries a cysteine to tyrosine substitution at amino acid position 342 (Cys342Tyr; C342Y) in fibroblast growth factor receptor 2 (FGFR2), equivalent to the FGFR2 mutation commonly associated with Crouzon syndrome. Crouzon syndrome is an autosomal dominant condition characterized by craniofacial anomalies. The FGFR2 C342Y mutation results in constitutive activation of the receptor and is associated with up‐regulation of osteogenic differentiation. Although premature closure of the coronal suture is the focus of most studies of Crouzon syndrome, cartilage elements of the skull are also known to be affected by this mutation. Fgfr2cC342Y/+ Crouzon syndrome mice commonly exhibit malocclusion of the jaws, most likely due to abnormal craniofacial form. The current paradigm of mandibular development assumes Meckel’s cartilage (MC) provides a model for mandibular development. Malformation of the mandible can precipitate a plethora of complications including disrupting development of the upper jaw and the palate, impediment of the airway, as well as altering the functional occlusion necessary for proper mastication. Here we investigate the relationship of Meckel’s cartilage to mandible development. Using Fgfr2cC342Y/+ Crouzon syndrome mice and their unaffected littermates (Fgfr2c+/+ mice) at embryonic days 15.5 and 17.5 we explore the form of Meckel’s cartilage and the developing mandible as Meckel’s cartilage begins to degrade. A histological assessment of the chondrocytes within Meckel’s cartilage reveals few differences in cell size between genotypes at either timepoint, however there are more chondrocytes present in the most anterior aspects of the cartilage in Fgfr2cC342Y/+ mice at E15.5. No differences between genotypes were found in osteoblast (ALP) or osteoclast (TRAP) activity of the mandibles at E15.5 but osteoclast activity was greater in unaffected Fgfr2c+/+ mice at E17.5. These data reveal that further investigation of Crouzon syndrome mice can uncover differential effects of the C342Y mutation in FGFR2 in cells other than those surrounding the coronal suture.

Clinical features and FGFR3 mutations of children with achondroplasia

To study the clinical features and fibroblast growth factor receptor 3 (FGFR3) gene mutations of children with achondroplasia (ACH) through an analysis of 17 cases. A retrospective analysis was performed on the clinical data and FGFR3 gene detection results of 17 children with ACH who were diagnosed from January 2009 to October 2021. Of the 17 children with ACH, common clinical manifestations included disproportionate short stature (100%, 17/17), macrocephaly (100%, 17/17), trident hand (82%, 14/17), and genu varum (88%, 15/17). The common imaging findings were rhizomelic shortening of the long bones (100%, 17/17) and narrowing of the lumbar intervertebral space (88%, 15/17). Major complications included skeletal dysplasia (100%, 17/17), middle ear dysfunction (82%, 14/17), motor/language developmental delay (88%, 15/17), chronic pain (59%, 10/17), sleep apnea (53%, 9/17), obesity (41%, 7/17), foramen magnum stenosis (35%, 6/17), and hydrocephalus (24%, 4/17). All 17 children (100%) had FGFR3 mutations, among whom 13 had c.1138G>A hotspot mutations of the FGFR3 gene, 2 had c.1138G>C mutations of the FGFR3 gene, and 2 had unreported mutations, with c.1252C>T mutations of the FGFR3 gene in one child and c.445+2_445+5delTAGG mutations of the FGFR3 gene in the other child. This study identifies the unreported mutation sites of the FGFR3 gene, which extends the gene mutation spectrum of ACH. ACH is a progressive disease requiring lifelong management through multidisciplinary collaboration.

Growth charts in FGFR2- and FGFR3-related faciocraniosynostoses

ObjectiveFaciocraniosynostoses (FCS) are malformations affecting the development of the bones of the skull and face, due to the premature closure of one or more craniofacial sutures, mostly secondary to activating Fibroblast Growth Factor Receptor (FGFR) 1–3 mutations. Gain-of-function FGFR3 mutations are also responsible for various conditions referred to as osteochondrodysplasia (OCD), characterized by structural and functional abnormalities of growth plate cartilages. We hypothesized that patients with FGFR-related faciocraniosynostoses may present extra-cranial growth anomalies. Study designWe retrospectively collected height and weight data from a cohort of 70 patients. Included patients were admitted for FGFR-related FCS between 2000 and 2021 at the Craniofacial Unit of Necker – Enfants Malades University Hospital in Paris, France. ResultsWe showed that FGFR-related faciocraniosynostoses had significantly reduced heights and weights relative to controls, and that two specific time periods (1–3 years and > 8 years of age) were associated with lower height and weight values. Four patients had received growth hormone treatment but remained below normal values for growth in height and weight. ConclusionsPatients with FGFR-related faciocraniosynostoses have clinically significant extra-cranial anomalies which are not currently investigated and managed in usual protocols; these patients could benefit from a systematic pre-pubertal endocrine assessment. More generally, our results extend the scope of extracranial anomalies in FGFR-related faciocraniosynostoses and support the hypothesis that all conditions with activating FGFR mutations affect both membranous ossification and long bones.

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

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

Human epidermal growth factor receptor 2 (HER2) and fibroblast growth factor receptor 3 (FGFR3) mutations to reveal biological pathways in urothelial carcinoma.

567 Background: Human epidermal growth factor receptor 2 (HER2) (gene name: ERBB2) is a member of the epidermal growth factor receptor (EGFR) family and when mutated, associated with higher grade and stage of localized bladder cancer. Two HER2-targeted antibody-drug conjugates (ADC), trastuzumab emtansine and trastuzumab deruxtecan, are currently approved by the Food and Drug Administration (FDA) for use in gastric/breast cancers with promising application in urothelial carcinoma. Fibroblast growth factor receptor 3 ( FGFR3) is the target of another FDA-approved tyrosine kinase inhibitor erdafitinib and generally associated with more favorable prognosis as well as upper tract carcinoma. The purpose of this study is to characterize ERBB2 and FGFR3 mutations in a prospectively collected cohort of urothelial cancers. Methods: Patients with localized upper or lower tract urothelial carcinoma diagnosed between 2014 and 2020 who underwent a targeted exome sequencing panel of up to 468 cancer genes were identified. If multiple tumors were sequenced, only the diagnostic specimen was included. Analysis of gene alterations, frequency, and associated co-mutations was performed. Descriptive statistics were used to compare baseline patient characteristics. Results: 381 unique ERBB2 or FGFR3 mutated urothelial carcinoma specimens were included in this study. Of note, ERBB2 and FGFR3 mutations were essentially mutually exclusive and included 122 (66%) ERBB2 mutated tumors and 259 (34%) FGFR3 mutated tumors. Patients with tumors harboring FGFR3 mutations were younger (median 70 years IQR 60-76 vs. 74 years IQR 66-78, p<0.05), while patients with ERBB2 mutated tumors were more likely to be male (85% vs 73%, p<0.05). At the time of diagnosis, ERBB2 tumors were more likely to present with advanced (pT2 or higher) disease compared to FGFR3 mutated tumors (48% vs 24%). ERBB2 mutated tumors were more likely associated with RB1, P53, and ARID1A mutations, while FGFR3 mutated tumors were more likely associated with CDKN2A/B and STAG2 mutations (Table). Conclusions: These data highlight divergent biological pathways for patients with targetable mutations in ERBB2 and FGFR3 and are consistent with prior findings in non-muscle invasive bladder cancer. ERBB2 mutated tumors are associated with male gender, more aggressive pathological features and co-mutations with RB1, P53, and ARID1A.[Table: see text]

Prognostic impact of fibroblast growth factor receptor (FGFR) genomic alterations and outcomes in patients with metastatic urothelial.

537 Background: FGFR mutations/translocations are druggable targets in metastatic urothelial cancer (mUC). However, the prognostic effect of these genomic alterations (GA) and their role in the response to conventional therapy remain poorly characterized. Methods: We undertook an observational retrospective study in four Academic Hospitals in Madrid, Spain. Clinical and molecular information of patients diagnosed of Urothelial Cancer (UC) between January 2010 and December 2020 was systematically reviewed. The objective of this work was to compare the outcome of mUC patients with GA in the FGFR 2-3 genes versus wild type tumors. Analyses for detection of FGFR translocations and mutations using DNA isolated from formalin-fixed and paraffinized tumor tissue samples consisted of either next-generation sequencing (Foundation One test; n = 68) or qualitative real-time polymerase chain reaction–based assays (n = 9) with TFGFR or QIAGEN therascreen® tests that evaluated somatic mutations within the FGFR2-3 gene: R248C, S249C, G370C and Y373C and fusions: FGFR3-TACC3v3, FGFR3-TACC3v1 and FGFR3-BAIAP2L1, FGFR2-BICC1 and FGFR2-CASP7. Overall response rate (ORR), Progression Free Survival (PFS) and Overall Survival (OS) were determined and Cox-regression analysis were performed to assess the prognostic impact of these alterations. Results: We identified 201 patients diagnosed with UC. Genomic profiling was available in 77 mUC with 28 patients harboring any FGFR GA. Regarding ORR to first line a trend towards a better outcome was identified in FGFR GA (mutation/translocation/fusion) vs wild type cases (57,7% vs 45,5%, p=0,46). However, median OS was significantly worse among FGFR GA (mutation/translocation) vs FGFR wt tumours (13.8 vs 26.2 months, p=0,021). Prognostic factors associated with an unfavorable outcome in multivariable analysis were visceral metastases (HR 7,29 95% CI 1.6-32,3), ECOG >1 (HR 7,03 95% CI 2,59-19,1), first line treatment with checkpoint inhibitors (HR 2,67; 95% CI 1,06-6,74) and the presence of FGFR GAs (HR 2,98, 95% CI 1.37-6.5). Conclusions: Despite a better response to first line treatment, overall FGFR GA showed to be an independent risk factor in mUC. Thus, this determination should be included in new prognostic models.[Table: see text]

Abstract P3-08-02: The frequency and somatic mutation landscape of Fibroblast growth factor receptor (FGFR) alterations in breast cancer

Abstract Background: FGFR dysregulation is observed in multiple cancers and targeting FGFR is an emerging therapeutic strategy with FDA approved treatments in bladder and cholangiocarcinoma. Here we examined the prevalence of FGFR mutations, fusions, and high-level amplifications in breast cancer, stratified by receptor subtype and local/metastatic status, in both Foundation Medicine (FM) and institutional Mayo Clinic (MC) cohorts. Methods: For the FM cohort, comprehensive genomic profiling (CGP) examining at least 324 genes for all classes of alterations, including FGFR1-4 was carried out for 32,048 breast cancers during the course of routine clinical care in a Clinical Laboratory Improvement Amendments (CLIA)-certified lab (Foundation Medicine Inc., Cambridge, MA, USA). Tumor mutational burden (TMB) was determined on up to 1.1 Mb, microsatellite instability high (MSI-High) was determined on up to 114 loci and predicted ancestry from >10,000 SNPs. Estrogen receptor (ER) and HER2 status were available for a subset of FM samples. Additionally, 131 patients with metastatic breast cancer from a subset of patients at three Mayo Clinic sites (MC cohort) with clinical characteristics and cancer-panel DNA sequencing data from a CLIA-certified lab (Tempus, Chicago, IL) were included. Results: In the FM cohort, the prevalence of FGFR1-4 high-level amplification (CN≥10) was 10.1%, while mutations (1.5%) and fusions (0.72%) were rare. Most amplifications occurred in FGFR1 (9.2%); most fusions and mutations occurred in FGFR2 (0.46%, 0.77%). FGFR alteration prevalence was highest in ER+/HER2- subtype (14.4%) and lowest in HER2+ disease (7.7%). FGFR alterations were more common in IDC (11.7%) than ILC (7.7%), p<3E-08. FGFR alterations were more prevalent in the metastatic setting relative to breast-biopsied disease (13.6% v 10.1%; OR = 1.4; p=2E-17), especially in the HER2+ (OR =1.9, p=0.004) and ER-/HER2- (OR = 1.9, p = 0.05) disease; no enrichment was seen in the ER+/HER2- metastases (OR =1.0, p = 1). FGFR amplifications were observed at a higher prevalence in patients with predicted East Asian ancestry, relative to patients with European ancestry (12.1% v 10.0%; p = 0.03). Overall, the most common activating mutations in FGFR were FGFR2 N549K (n=85), FGFR1 N546K (n=78), FGFR4 V510M (n=28), FGFR2 K659E (n=28), FGFR4 V510L (n=20), and FGFR2 Y375C (n=15). The most common recurrent fusions were FGFR3:TACC3 (n=36), FGFR2:TACC2 (n=17), FGFR1:TACC1 (n=9), FGFR1:BAG4 (n=6), and FGFR2:ATE1 (n=5). In patients with FGFR amplifications, the most frequently co-occurring alterations were ZNF703 (78.4%), TP53 (51.5%), CCND1 (36.1%), FGF3/4/19 (32.9 - 34.4%), PIK3CA (30.7%), MYC (29.6%), ESR1 (17.2%), EMSY (16.3%), and PTEN (10.6%). Significant co-occurrence was observed for a number of genes including FGF3/4/19, CDK4, and CDK8 (all OR>2, p<1E-07); mutual exclusivity was observed with PIK3R1, BRCA1, and BRCA2 (all OR <0.5, p<4E-13), among other genes. In the 131 metastatic tumors from MC, the prevalence of FGFR1-4 high-level amplifications was 19.8% [FGFR1 (12.4%), FGFR2 (7.4%), and FGFR3 (0.8%)]. The prevalence of high-level FGFR amplifications did not differ by clinical subtypes: HR-/HER2- (7/31), HR+/HER2- (15/79), and HER2+ (2/11), p=0.68. Conclusions: High-level FGFR amplifications are observed in >11% of breast cancers, especially the ER+/HER2- subtype, while mutations/fusions are rare. These data support the ongoing studies evaluating targeted therapies for FGFR amplified ER + breast cancer. Correlations with clinical information (MC cohort) and associations with actionable alterations are ongoing and may inform potential combination strategies. Citation Format: Karthik V Giridhar, Ethan S Sokol, Peter T Vedell, Jason P Sinnwell, Aakash Desai, Tufia C Haddad, Ciara C O’Sullivan, Roberto A Leon-Ferre, Siddhartha Yadav, Kostandinos Sideras, Brenda Ernst, Minetta C Liu, Abe Eyman Casey, Xiaojia Tang, Zoe Fleischmann, Karthikeyan Murugesan, Krishna R Kalari, Matthew P Goetz. The frequency and somatic mutation landscape of Fibroblast growth factor receptor (FGFR) alterations in breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-08-02.

Abstract P5-08-12: Efficacy of futibatinib, an irreversible fibroblast growth factor receptor (FGFR) inhibitor, in breast cancer models with FGFR alterations

Abstract Purpose: Several FGFR alterations have been found in breast cancer, however, their role as a therapeutic target in breast has been controversial. Futibatinib (TAS-120; Taiho) is a novel, selective pan-FGFR inhibitor which irreversibly binds to and inhibits FGFR1-4 at nanomolar concentrations. We sought to determine the efficacy of futibatinib in breast cancer models with differing FGFR alterations. Experimental Design: In vivo, antitumor efficacy was evaluated by tumor growth curves and event-free survival in a panel of patient-derived xenografts (PDXs) from breast cancer patients with different FGFR1-4 alterations. Genomic alterations in the PDXs were characterized by next generation sequencing. Correlation of FGFR gene expression in matched patient tumors and PDXs was analyzed by RNA sequencing. In vitro, FGFR2 Y375C mutant and FGFR2-BICC1 fusion expressing MCF10A cell lines were generated, and effect on cell proliferation, colony formation assay, and cell signaling was assessed with and without futibatinib. Frequency of FGFR mutations and FGFR2 amplification was compiled from internal and public databases. Results: Breast cancer PDXs varied in their expression of FGFR1-4. FGFR gene expression significantly correlated between matched patient tumors and PDXs derived from them, however, PDXs had higher levels of FGFR3 and FGFR4 expression compared to patient samples. Futibatinib inhibited tumor growth in three of 10 PDX models, with tumor stabilization in a FGFR2 amplified model and prolonged tumor regression (more than 110 days) in a PDX bearing a FGFR2 Y375C mutation. In vitro, expression of FGFR2 Y375C, as well as FGFR2-BICC fusion in normal-like MCF10A cells enhanced growth, colony formation ability and FGFR signaling. Cells expressing FGFR2 Y375C as well as FGFR2-BICC fusions were more sensitive to futibatinib. In the five breast cancer genomic series we analyzed, FGFR2 mutations and amplifications were found in 1.1%-2.6% and 1.4%-2.5%, respectively. Conclusions: Futibatinib had single agent activity of selected breast cancer PDX models. FGFR2 activating mutations and amplification may represent rare but promising therapeutic targets to FGFR inhibition. Citation Format: Turcin Saridogan, Argun Akcakanat, Ming Zhao, Kurt W. Evans, Erkan Yuca, Stephen Scott, Bryce P. Kirby, Xiaofeng Zheng, Senthil Damodaran, Funda Meric-Bernstam. Efficacy of futibatinib, an irreversible fibroblast growth factor receptor (FGFR) inhibitor, in breast cancer models with FGFR alterations [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-08-12.

FIGHT-101, a first-in-human study of potent and selective FGFR 1-3 inhibitor pemigatinib in pan-cancer patients with FGF/FGFR alterations and advanced malignancies

The phase I/II FIGHT-101 study (NCT02393248) evaluated safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of pemigatinib, a potent and selective fibroblast growth factor receptor (FGFR) 1-3 inhibitor, as monotherapy or in combination therapy, for refractory advanced malignancies, with and without fibroblast growth factor (FGF) and receptor (FGFR) gene alterations. Eligible, molecularly unselected patients with advanced malignancies were included in part 1 (dose escalation; 3+ 3 design) to determine the maximum tolerated dose. Part 2 (dose expansion) evaluated the recommended phase II dose in tumors with or where FGF/FGFR activity is relevant. Patients (N= 128) received pemigatinib 1-20 mg once daily intermittently (2 weeks on/1 week off; n= 70) or continuously (n= 58). No dose-limiting toxicities were reported. Doses ≥4 mg were pharmacologically active (maximum tolerated dose not reached; recommended phase II dose 13.5 mg once daily). The most common treatment-emergent adverse event (TEAE) was hyperphosphatemia (75.0%; grade ≥3, 2.3%); the most common grade ≥3 TEAE was fatigue (10.2%). Dose interruption, dose reduction, and TEAE-related treatment discontinuation occurred in 66 (51.6%), 14 (10.9%), and 13 (10.2%) patients, respectively. Overall, 12 partial responses were achieved, most commonly in cholangiocarcinoma (n= 5) as well as in a broad spectrum of tumors including head and neck, pancreatic, gallbladder, uterine, urothelial carcinoma, recurrent pilocytic astrocytoma, and non-small-cell lung cancer (each n= 1); median duration of response was 7.3 months [95% confidence interval (CI) 3.3-14.5 months]. Overall response rate was highest for patients with FGFR fusions/rearrangements [n= 5; 25.0% (95% CI 8.7% to 49.1%)], followed by those with FGFR mutations [n= 3; 23.1% (95% CI 5.0% to 53.8%)]. Pemigatinib was associated with a manageable safety profile and pharmacodynamic and clinical activity, with responses seen across tumors and driven by FGFR fusions/rearrangements and mutations. These results prompted a registrational study in cholangiocarcinoma and phase II/III trials in multiple tumor types demonstrating the benefit of precision therapy, even in early phase trials.

Updated analysis with longer follow up of a phase 2a study evaluating erdafitinib in Asian patients (pts) with advanced cholangiocarcinoma (CCA) and fibroblast growth factor receptor (FGFR) alterations.

430 Background: Pts with CCA progressing after first-line therapy have limited treatment options. We report an updated analysis of the ongoing LUC2001 open-label, multicenter, phase 2a study (NCT02699606) investigating the efficacy and safety of erdafitinib in Asian pts with advanced CCA and FGFR alterations who progressed after ≥1 prior systemic treatment. Methods: Eligible adults (aged ≥18 years) received erdafitinib 8 mg once daily (QD) with pharmacodynamically guided up-titration to 9 mg QD. The primary endpoint was objective response rate (ORR; RECIST 1.1); secondary endpoints included best overall response (BOR), disease control rate (DCR), duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. Survival estimates were determined by the Kaplan–Meier method. Results: Of 232 patients with CCA who underwent molecular screening, 39 (16.8%) had FGFR alterations (21 [9.1%] fusions and 19 [8.2%] mutations). Overall, 22 (9.5%) eligible pts (median age, 52 [range, 29–69] years) were enrolled and received treatment. Median follow-up was 22.4 (range, 2.3–47.0) months; median treatment duration was 6.2 (range, 1.5–35.6) months. All 22 pts received ≥1 line of prior systemic therapy and 12 (55.0%) pts had ≥2 prior lines of therapy. The ORR was 40.9% (95% CI, 20.7%–63.6%) and median time to response was 1.8 (range, 1.5–5.6) months. Median DOR was 7.3 (95% CI, 3.7–17.5) months, median PFS was 5.6 (95% CI, 3.6–12.7) months, and median OS was 40.2 (95% CI: 9.9–not estimable) months (Table). Responses were observed in 8/14 pts with FGFR fusions and 1/8 pts with FGFR mutations and in pts who received 1 or ≥2 prior lines of therapy. All 22 pts had ≥1 treatment-emergent adverse event (TEAE), the most common being dry mouth (15/22 [68.2%]) and stomatitis (14/22 [63.6%]). Grade ≥3 TEAEs occurred in 15/22 (68.2%) pts (11/22 [50.0%] were treatment related), of which the most common were stomatitis (3/22 [13.6%]) and alanine aminotransferase (ALT) increased (3/22 [13.6%]); 11/22 (50.0%) pts had ≥1 serious TEAE (1/22 [4.5%] pts had a serious treatment-related TEAE). A TEAE leading to death occurred in 1 patient (sepsis; not treatment-related). Conclusions: Asian pts with advanced CCA and FGFR alterations treated with erdafitinib had durable efficacy and a manageable safety profile, supporting the earlier findings of erdafitinib benefit in this population. Clinical trial information: NCT02699606. [Table: see text]