Exploring a distinct FGFR2::DLG5 rearrangement in a low-grade neuroepithelial tumor: A case report and mini-review of protein fusions in brain tumors.

We report the novel clinical presentation of a primary brain neoplasm in a 30-year-old man with a mass-like area in the anteromedial temporal lobe. Histopathological analysis revealed a low-grade neuroepithelial tumor with cytologically abnormal neurons and atypical glial cells within the cerebral cortex. Molecular analysis showed a previously undescribed FGFR2::DLG5 rearrangement. We discuss the clinical significance and molecular implications of this fusion event, shedding light on its potential impact on tumor development and patient prognosis. Additionally, an extensive review places the finding in this case in the context of protein fusions in brain tumors in general and highlights their diverse manifestations, underlying molecular mechanisms, and therapeutic implications.

Generation of salivary glands derived from pluripotent stem cells via conditional blastocyst complementation.

Whole salivary gland generation and transplantation offer potential therapies for salivary gland dysfunction. However, the specific lineage required to engineer complete salivary glands has remained elusive. In this study, we identify the Foxa2 lineage as a critical lineage for salivary gland development through conditional blastocyst complementation (CBC). Foxa2 lineage marking begins at the boundary between the endodermal and ectodermal regions of the oral epithelium before the formation of the primordial salivary gland, thereby labeling the entire gland. Ablation of Fgfr2 within the Foxa2 lineage in mice leads to salivary gland agenesis. We reversed this phenotype by injecting donor pluripotent stem cells into the mouse blastocysts, resulting in mice that survived to adulthood with salivary glands of normal size, comparable to those of their littermate controls. These findings demonstrate that CBC-based salivary gland regeneration serves as a foundational experimental approach for future advanced cell-based therapies.

Molecular and morphologic characterization of intraductal tubulopapillary neoplasms of pancreas with novel potentially targetable fusions.

Intraductal tubulopapillary neoplasms (ITPNs) are rare pancreatic tumors with distinct histological and molecular features. Distinction of ITPN from other pancreatic neoplasms is crucial given the known favorable prognosis and the high frequency and diversity of potentially targetable fusions in ITPN. While the histological features of ITPN are well documented, there are few reports on the cytological features, and molecular characterization of ITPN. The authors reported three cases diagnosed in their laboratory between 2016 and 2021. Clinical data, cytomorphological and histological features, with immunophenotypic and molecular characterizations of these cases are described and compared with those reported in the literature. All 3 cases were diagnosed as ITPN based on the microscopic presence of intraductal nodules composed of tightly packed small tubular glands lined by cuboidal cells lacking apparent mucin. On molecular profiling KRAS and TP53 variants were found in Case 1, FGFR2-INA fusion in Case 2, and STARD3NL-BRAF fusion was detected in Case 3. Immunohistochemistry (IHC) revealed that the neoplastic cells in Case 1 were MUC2 positive and MUC6 negative, but in Cases 2 and 3, were negative for MUC2 and positive for MUC6. These results demonstrate the immunophenotypic and molecular variabilities of histologically similar pancreatic neoplasms. The absence of alterations characteristic of more common pancreatic neoplasms should prompt the consideration of fusion studies in morphologically relevant cases. The combination of morphological, IHC, and molecular analyses is important for reliable identification of ITPN given its potential clinical management implications.

Bemarituzumab plus mFOLFOX6 as first-line treatment in East Asian patients with FGFR2b-overexpressing locally advanced or metastatic gastric/gastroesophageal junction cancer: subgroup of FIGHT final analysis.

BACKGROUND: In the FIGHT study (NCT03694522) bemarituzumab, a humanized monoclonal antibody selective for fibroblast growth factor receptor 2b (FGFR2b), plus mFOLFOX6 showed clinically meaningful efficacy in patients with FGFR2b-positive (2+/3+ membranous staining by immunohistochemistry) locally advanced unresectable/metastatic gastric/gastroesophageal cancer (G/GEJC). A meaningful proportion of patients in FIGHT were enrolled in East Asia, reflecting global epidemiology of G/GEJC. METHODS: This subgroup analysis of the global, phase 2, double-blind FIGHT study included all patients enrolled in East Asian sites. Patients were randomized 1:1 to bemarituzumab-mFOLFOX6 (15 mg/kg and one 7.5 mg/kg dose on cycle 1, day 8) or matching placebo-mFOLFOX6. The primary endpoint was investigator-assessed progression-free survival (PFS). Secondary endpoints included overall survival (OS), objective response rate, and safety. Efficacy was evaluated after a minimum follow-up of 24 months. RESULTS: The East Asian subgroup comprised 89 patients (57% of overall study population); 45 were randomized to bemarituzumab-mFOLFOX6 and 44 to placebo-mFOLFOX6. Median PFS (95% confidence interval [CI]) was 12.9 months (8.8-17.9) with bemarituzumab-mFOLFOX6 and 8.2 months (5.6-10.3) with placebo-mFOLFOX6 (HR 0.50, 95% CI 0.29-0.87); median OS (95% CI) was 24.7 months (13.8-33.1) vs 12.9 months (9.3-21.4), respectively (HR 0.56, 95% CI 0.32-0.96). Treatment benefit was more pronounced in patients with FGFR2b-positive G/GEJC in ≥ 10% of tumor cells. No new safety signals were reported. CONCLUSION: In East Asian patients with FGFR2b-positive advanced/metastatic G/GEJC enrolled in the global FIGHT study, bemarituzumab-mFOLFOX6 showed clinically meaningful outcomes over placebo-mFOLFOX6.

Do Fibroblast Growth Factor Receptor (FGFR) 2 and 3 Proteins Play a Role in Prognosis of Invasive Urothelial Bladder Carcinoma?

Background & Objective: Bladder carcinoma ranks second in prevalence among males in Egypt. As a family of tyrosine kinases, fibroblast growth factor receptor (FGFR) dysregulation has been linked to some malignancies in humans. The aim of this study is to analyze the clinicopathological data of patients while investigating FGFR2 and FGFR3 immunohistochemical expression in invasive urothelial bladder carcinoma. Methods: This retrospective cross-sectional study included 60 invasive urothelial carcinoma (UC) cases in the Pathology department, Faculty of Medicine, Menoufia University, from 2009 to 2020. All biopsies were stained for FGFR2 and FGFR3 antibodies. Complete clinical data were available for 44 patients treated and followed in clinical oncology and nuclear medicine departments. Results: Advanced stage and high grade are significantly correlated with FGFR2 positivity (P=0.048 and 0.044, respectively). Cases presented with Perineural invasion showed a higher percentage of FGFR2 (P=0.023). There is a significant indirect linear correlation between FGFR3 expression and lymph node positivity (r= -0.265, P=0.041). Conclusion: A high FGFR2 expression could be associated with poor prognostic parameters, while high FGFR3 expression would be associated with good prognostic parameters. These findings might highlight the importance of FGFR-targeted therapy as a FGFR2 antagonist and FGFR3 agonist for the treatment of urothelial carcinoma patients.

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.

Circulating tumor DNA molecular analyses and real-world evidence outcomes of FGFR2 amplified gastroesophageal cancers.

PURPOSE: In addition to the existing biomarkers HER2 and PD-L1, FGFR2b has become an area of interest for the development of new targeted-based treatment. Given that clinical evaluation of FGFR2 targeted therapy is underway, we sought to elucidate the genomic landscape of FGFR2amp in gastroesophageal cancer (GEC) using a circulating tumor DNA (ctDNA) platform. MATERIALS AND METHODS: We retrospectively evaluated the Guardant Health database from 2017 to 2022 for patients with GECs with Guardant360 ctDNA next-generation sequencing (NGS) performed. We assessed co-occurring genetic alterations for patients who harbored FGFR2amp versus FGFR2null. We also explored real-world evidence database with Guardant Health, publicly available genomic databases (MSK cohort using cBioPortal), and pooled clinical data from large-volume cancer centers for FGFR2amp GECs. RESULTS: Less than 4% of patients with GEC in the Guardant Health database were identified to be FGFR2amp. The most commonly co-occurring gene mutations were TP53, CTNNB1, CDH1, and RHOA. Upon interrogation of the MSK cohort, these same genes were not significant on tissue NGS in the FGFR2amp cohort of GEC. In the pooled institutional cohort, we noted that FGFR2amp tumors were most commonly involving the gastroesophageal junction (GEJ). The overall survival of these patients was noted at 13.1 months. CONCLUSION: FGFR2 is a validated target in GECs, and the contexture of FGFR2amp will be important in defining patient subgroups with responses to FGFR2-directed therapy. Using ctDNA to provide a more detailed genomic landscape in patients with GECs will allow the advancement of targeted therapy in the near future for these aggressive cancers.

Single-cell RNA-seq reveals novel interaction between muscle satellite cells and fibro-adipogenic progenitors mediated with FGF7 signalling.

BACKGROUND: Muscle satellite cells (MuSCs) exert essential roles in skeletal muscle adaptation to growth, injury and ageing, and their functions are extensively modulated by microenvironmental factors. However, the current knowledge about the interaction of MuSCs with niche cells is quite limited. METHODS: A 10× single-cell RNA sequencing (scRNA-seq) was performed on porcine longissimus dorsi and soleus (SOL) muscles to generate a single-cell transcriptomic dataset of myogenic cells and other cell types. Sophisticated bioinformatic analyses, including unsupervised clustering analysis, marker gene, gene set variation analysis (GSVA), AUCell, pseudotime analysis and RNA velocity analysis, were performed to explore the heterogeneity of myogenic cells. CellChat analysis was used to demonstrate cell-cell communications across myogenic cell subpopulations and niche cells, especially fibro-adipogenic progenitors (FAPs). Integrated analysis with human and mice datasets was performed to verify the expression of FGF7 across diverse species. The role of FGF7 on MuSC proliferation was evaluated through administering recombinant FGF7 to porcine MuSCs, C2C12, cardiotoxin (CTX)-injured muscle and d-galactose ( d-gal)-induced ageing model. RESULTS: ScRNA-seq totally figured out five cell types including myo-lineage cells and FAPs, and myo-lineage cells were further classified into six subpopulations, termed as RCN3+, S100A4+, ID3+, cycling (MKI67+), MYF6+ and MYMK+ satellite cells, respectively. There was a higher proportion of cycling and MYF6+ cells in the SOL population. CellChat analysis uncovered a particular impact of FAPs on myogenic cells mediated by FGF7, which was relatively highly expressed in SOL samples. Administration of FGF7 (10 ng/mL) significantly increased the proportion of EdU+ porcine MuSCs and C2C12 by 4.03 ± 0.81% (P < 0.01) and 6.87 ± 2.17% (P < 0.05), respectively, and knockdown of FGFR2 dramatically abolished the pro-proliferating effects (P < 0.05). In CTX-injured muscle, FGF7 significantly increased the ratio of EdU+/Pax7+ cells by 15.68 ± 5.45% (P < 0.05) and elevated the number of eMyHC+ regenerating myofibres by 19.7 ± 4.25% (P < 0.01). Under d-gal stimuli, FGF7 significantly reduced γH2AX+ cells by 17.19 ± 3.05% (P < 0.01) in porcine MuSCs, induced EdU+ cells by 4.34 ± 1.54% (P < 0.05) in C2C12, and restored myofibre size loss and running exhaustion in vivo (all P < 0.05). CONCLUSIONS: Our scRNA-seq reveals a novel interaction between muscle FAPs and satellite cells mediated by FGF7-FGFR2. Exogenous FGF7 augments the proliferation of satellite cells and thus benefits muscle regeneration and counteracts age-related myopathy.

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.

A journey in the world of craniofacial development: From 1968 to the future.

This article is based on my talk at the meeting "3rd Advances in Craniosynostosis: Basic Science to Clinical Practice", held at University College, London, on 25 August 2023. It describes my contribution, together with that of my research team and external collaborators, to the field of craniofacial development. This began with my PhD research on the effects of excess vitamin A in rat embryos, which led to a study of normal as well as abnormal formation of the cranial neural tube. Many techniques for analysing morphogenetic change became available to me over the years: whole embryo culture, scanning and transmission electron microscopy, cell division analysis, immunohistochemistry and biochemical analysis of the extracellular matrix. The molecular revolution of the 1980s, and key collaborations with international research teams, enabled functional interpretation of some of the earlier morphological observations and required a change of experimental species to the mouse. Interactions between the molecular and experimental analysis of craniofacial morphogenesis in my laboratory with specialists in molecular genetics and clinicians brought my research journey near to my original aim: to contribute to a better understanding of the causes of human congenital anomalies.

Perinatal imaging findings of a fetus with Pfeiffer syndrome and a heterozygous c.1019A>G, p.Tyr340Cys (Y340C) mutation in FGFR2 presenting a cloverleaf skull, craniosynostosis and short limbs on prenatal ultrasound mimicking thanatophoric dysplasia type II.

OBJECTIVE: We present perinatal imaging findings of a fetus with Pfeiffer syndrome and a heterozygous c.1019A>G, p.Tyr340Cys (Y340C) mutation in FGFR2 presenting a cloverleaf skull, craniosynostosis and short limbs on prenatal ultrasound mimicking thanatophoric dysplasia type II (TD2). CASE REPORT: A 37-year-old, gravida 2, para 1, woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 46,XY. However, craniofacial anomaly was found on prenatal ultrasound at 21 weeks of gestation, which showed a cloverleaf skull with severe craniosynostosis and relatively short straight long bones. Fetal magnetic resonance imaging (MRI) analysis at 22 weeks of gestation showed a cloverleaf skull, proptosis and relatively shallowing of the sylvian fissures. Prenatal ultrasound at 24 weeks of gestation showed a fetus with a cloverleaf skull with a biparietal diameter (BPD) of 6.16 cm (equivalent to 24 weeks), an abdominal circumference (AC) of 18.89 cm (equivalent to 24 weeks) and a femur length (FL) of 3.65 cm (equivalent to 21 weeks). A tentative diagnosis of TD2 was made. The pregnancy was subsequently terminated, and a 928-g malformed fetus was delivered with severe craniosynostosis, proptosis, midface retrusion, a cloverleaf skull, broad thumbs and broad big toes. The broad thumbs were medially deviated. Whole body X-ray showed a cloverleaf skull and straight long bones. However, molecular analysis of FGFR3 on the fetus revealed no mutation in the target regions. Subsequent whole exome sequencing (WES) on the DNA extracted from umbilical cord revealed a heterozygous c.1019A>G, p.Tyr340Cys (Y340C) mutation in the FGFR2 gene. CONCLUSION: Fetuses with a Y340C mutation in FGFR2 may present a cloverleaf skull on prenatal ultrasound, and WES is useful for a rapid differential diagnosis of Pfeiffer syndrome from TD2 under such a circumstance.

FGFR2-triggered autophagy and activation of Nrf-2 reduce breast cancer cell response to anti-ER drugs.

BACKGROUND: Genetic abnormalities in the FGFR signalling occur in 40% of breast cancer (BCa) patients resistant to anti-ER therapy, which emphasizes the potential of FGFR-targeting strategies. Recent findings indicate that not only mutated FGFR is a driver of tumour progression but co-mutational landscapes and other markers should be also investigated. Autophagy has been recognized as one of the major mechanisms underlying the role of tumour microenvironment in promotion of cancer cell survival, and resistance to anti-ER drugs. The selective autophagy receptor p62/SQSTM1 promotes Nrf-2 activation by Keap1/Nrf-2 complex dissociation. Herein, we have analysed whether the negative effect of FGFR2 on BCa cell response to anti-ER treatment involves the autophagy process and/or p62/Keap1/Nrf-2 axis. METHODS: The activity of autophagy in ER-positive MCF7 and T47D BCa cell lines was determined by analysis of expression level of autophagy markers (p62 and LC3B) and monitoring of autophagosomes' maturation. Western blot, qPCR and proximity ligation assay were used to determine the Keap1/Nrf-2 interaction and Nrf-2 activation. Analysis of 3D cell growth in Matrigel® was used to assess BCa cell response to applied treatments. In silico gene expression analysis was performed to determine FGFR2/Nrf-2 prognostic value. RESULTS: We have found that FGFR2 signalling induced autophagy in AMPKα/ULK1-dependent manner. FGFR2 activity promoted dissociation of Keap1/Nrf-2 complex and activation of Nrf-2. Both, FGFR2-dependent autophagy and activation of Nrf-2 were found to counteract the effect of anti-ER drugs on BCa cell growth. Moreover, in silico analysis showed that high expression of NFE2L2 (gene encoding Nrf-2) combined with high FGFR2 expression was associated with poor relapse-free survival (RFS) of ER+ BCa patients. CONCLUSIONS: This study revealed the unknown role of FGFR2 signalling in activation of autophagy and regulation of the p62/Keap1/Nrf-2 interdependence, which has a negative impact on the response of ER+ BCa cells to anti-ER therapies. The data from in silico analyses suggest that expression of Nrf-2 could act as a marker indicating potential benefits of implementation of anti-FGFR therapy in patients with ER+ BCa, in particular, when used in combination with anti-ER drugs.

Clinical Developments and Challenges in Treating FGFR2-Driven Gastric Cancer.

Recent advances in the treatment of gastric cancer (GC) with chemotherapy, immunotherapy, anti-angiogenic therapy and targeted therapies have yielded some improvement in survival outcomes; however, metastatic GC remains a lethal malignancy and amongst the leading causes of cancer-related mortality worldwide. Importantly, the ongoing molecular characterisation of GCs continues to uncover potentially actionable molecular targets. Among these, aberrant FGFR2-driven signalling, predominantly arising from FGFR2 amplification, occurs in approximately 3-11% of GCs. However, whilst several inhibitors of FGFR have been clinically tested to-date, there are currently no approved FGFR-directed therapies for GC. In this review, we summarise the significance of FGFR2 as an actionable therapeutic target in GC, examine the recent pre-clinical and clinical data supporting the use of small-molecule inhibitors, antibody-based therapies, as well as novel approaches such as proteolysis-targeting chimeras (PROTACs) for targeting FGFR2 in these tumours, and discuss the ongoing challenges and opportunities associated with their clinical development.

The combination of gemcitabine plus an anti-FGFR inhibitor can have a synergistic antitumor effect on FGF-activating cholangiocarcinoma.

Anti-FGFR treatment for cholangiocarcinoma (CCA) with fibroblast growth factor receptor (FGFR) alteration is a promising treatment option. Since the antitumor mechanisms of anti-FGFR inhibitors and conventional cytotoxic drugs differ, synergistic effects can be possible. This study aimed to evaluate the efficacy of the combined administration of gemcitabine (GEM) and pemigatinib in CCA cells with FGFR2 alterations. To simulate the treatment for patients with 3 kinds of CCA, chemonaïve CCA with activation of the FGF pathway, chemo-resistant CCA with activation of the FGF pathway, and CCA without FGF pathway activation (as controls), we evaluated 3 different CCA cell lines, CCLP-1 (with a FGFR2 fusion mutation), CCLP-GR (GEM-resistant cells established from CCLP-1), and HuCCT1 (without FGFR mutations). There was no significant difference between CCLP-1 and HuCCT1 in GEM suspensibility (IC50 = 19.3, 22.6 mg/dl, p = 0.1187), and the drug sensitivity to pemigatinib did not differ between CCLP-1 and CCLP-GR (IC50 = 7.18,7.60 nM, p = 0.3089). Interestingly, only CCLP-1 showed a synergistic effect with combination therapy consisting of GEM plus pemigatinib in vitro and in vivo. In a comparison of the reaction to GEM exposure, only CCLP-1 cells showed an increase in the activation of downstream proteins in the FGF pathway, especially FRS2 and ERK. In association with this reaction, cell cycle and mitosis were increased with GEM exposure in CCLP-1, but HuCCT1/CCLP-GR did not show this reaction. Our results suggested that combination therapy with GEM plus pemigatinib is a promising treatment for chemonaïve patients with CCA with activation of the FGF pathway.

Genetic insights into the 'sandwich fusion' subtype of Klippel-Feil syndrome: novel FGFR2 mutations identified by 21 cases of whole-exome sequencing.

BACKGROUND: Klippel-Feil syndrome (KFS) is a rare congenital disorder characterized by the fusion of two or more cervical vertebrae during early prenatal development. This fusion results from a failure of segmentation during the first trimester. Although six genes have previously been associated with KFS, they account for only a small proportion of cases. Among the distinct subtypes of KFS, "sandwich fusion" involving concurrent fusion of C0-1 and C2-3 vertebrae is particularly noteworthy due to its heightened risk for atlantoaxial dislocation. In this study, we aimed to investigate novel candidate mutations in patients with "sandwich fusion." METHODS: We collected and analyzed clinical data from 21 patients diagnosed with "sandwich fusion." Whole-exome sequencing (WES) was performed, followed by rigorous bioinformatics analyses. Our focus was on the six known KFS-related genes (GDF3, GDF6, MEOX1, PAX1, RIPPLY2, and MYO18). Suspicious mutations were subsequently validated through in vitro experiments. RESULTS: Our investigation revealed two novel exonic mutations in the FGFR2 gene, which had not previously been associated with KFS. Notably, the c.1750A > G variant in Exon 13 of FGFR2 was situated within the tyrosine kinase domain of the protein, in close proximity to several established post-translational modification sites. In vitro experiments demonstrated that this certain mutation significantly impacted the function of FGFR2. Furthermore, we identified four heterozygous candidate variants in two genes (PAX1 and MYO18B) in two patients, with three of these variants predicted to have potential clinical significance directly linked to KFS. CONCLUSIONS: This study encompassed the largest cohort of patients with the unique "sandwich fusion" subtype of KFS and employed WES to explore candidate mutations associated with this condition. Our findings unveiled novel variants in PAX1, MYO18B, and FGFR2 as potential risk mutations specific to this subtype of KFS.

Navigating uncharted territory: a case report and literature review on the remarkable response to personalized crizotinib containing combinational therapy in a pazopanib refractory patient with novel alterations.

This paper presents a patient with a novel Ig-like-III domain fibroblast growth factor receptor (FGFR2) alteration (W290_P307>C) along with CDKN2A/B alterations and a cadherin 1 (CDH1) alteration. Initial responsiveness to pazopanib monotherapy was encouraging, yet progression occurred after 7.5 months. Following progression, the molecular tumor board recommended a combination therapy approach comprising pazopanib, crizotinib, and palbociclib to target all of the changed pathways at the same time. Pazopanib was chosen to specifically target the FGFR2 alteration, while crizotinib was selected due to its potential synthetic lethality with the CDH1 alteration. In addition, the CDK4/6 inhibitor palbociclib was administered to address the CDKN2A/B alterations. The patient exhibited a remarkable and sustained response to this innovative combination. This case not only underscores the potential of tyrosine kinase inhibitors, exemplified by pazopanib, as a viable alternative for patients without access to pan-FGFR inhibitors, but it also emphasizes their efficacy beyond commonly detected point mutations and rearrangements. Notably, the outstanding response to combination therapy, including crizotinib, in a patient with a CDH1 alteration, further substantiates the preclinical evidence of synthetic lethality between crizotinib and CDH1 alterations. To our knowledge, this represents the first clinical evidence demonstrating the efficacy of crizotinib in a patient with a CDH1 alteration. Through careful dosage adjustments and consideration of individualized genomic information, this case exemplifies the power of personalized medicine in achieving favorable treatment outcomes.

Elucidating the Role of Wildtype and Variant FGFR2 Structural Dynamics in (Dys)Function and Disorder.

The fibroblast growth factor receptor 2 (FGFR2) gene is one of the most extensively studied genes with many known mutations implicated in several human disorders, including oncogenic ones. Most FGFR2 disease-associated gene mutations are missense mutations that result in constitutive activation of the FGFR2 protein and downstream molecular pathways. Many tertiary structures of the FGFR2 kinase domain are publicly available in the wildtype and mutated forms and in the inactive and activated state of the receptor. The current literature suggests a molecular brake inhibiting the ATP-binding A loop from adopting the activated state. Mutations relieve this brake, triggering allosteric changes between active and inactive states. However, the existing analysis relies on static structures and fails to account for the intrinsic structural dynamics. In this study, we utilize experimentally resolved structures of the FGFR2 tyrosine kinase domain and machine learning to capture the intrinsic structural dynamics, correlate it with functional regions and disease types, and enrich it with predicted structures of variants with currently no experimentally resolved structures. Our findings demonstrate the value of machine learning-enabled characterizations of structure dynamics in revealing the impact of mutations on (dys)function and disorder in FGFR2.

FGFR2 and miR-889-3p expression in oral cancer is associated with cervical lymph node metastasis.

OBJECTIVE: Fibroblast growth factor receptor-2 (FGFR2) and miR-889-3p expression in oral squamous cell carcinoma (OSCC) tumours were compared to normal controls. We then examined the relationship between miR-889-3p, FGFR2 expression and patient clinicopathological features. MATERIALS AND METHODS: The interaction of FGFR2 and miR-889-3p was investigated using bioinformatics. Then, OSCC tumour biopsies and normal gingiva were collected and processed for expression analysis of FGFR2-specific mRNA and miR-889-3p using real-time PCR. Immunohistochemistry evaluated the expression of the FGFR2 protein. RESULTS: The protein and mRNA expression levels of FGFR2 were significantly greater in tumours when contrasted with controls. Expression of miR-889-3p was significantly lower in OSCC compared to normal tissues. The FGFR2 and miR-889-3p expressions were inversely related (-0.86 and -0.73, respectively) in both cases and controls. Changes in miR-889-3p and FGFR2 expression in tumour tissues were associated with lymph node metastasis (LNM), with ~0.57 and ~3.0 folds of change in positive-LNM patients, respectively. CONCLUSION: Decreased expression of miR-889-3p in OSCC tumours suggests that miR-889-3p functions as a tumour suppressor gene. Overexpression of FGFR2 further proves the role of miR-889-3p in the regulation of the FGFR2 pathway. This was further confirmed by showing differences in miR-889-3p expression in positive and negative LNM cases.

High-Throughput RNA-HCR-FISH Detection of Endogenous Pre-mRNA Splice Variants.

RNA-fluorescence in situ hybridization (RNA-FISH) is an essential and widely used tool for visualizing RNA molecules in intact cells. Recent advances have increased RNA-FISH sensitivity, signal detection efficiency, and throughput. However, detection of endogenous mRNA splice variants has been challenging due to the limits of visualization of RNA-FISH fluorescence signals and due to the limited number of RNA-FISH probes per target. HiFENS (high-throughput FISH detection of endogenous pre-mRNA splicing isoforms) is a method that enables visualization and relative quantification of mRNA splice variants at single-cell resolution in an automated high-throughput manner. HiFENS incorporates HCR (hybridization chain reaction) signal amplification strategies to enhance the fluorescence signal generated by low abundance transcripts or a small number of FISH probes targeting short stretches of RNA, such as single exons. The technique offers a significant advance in high-throughput FISH-based RNA detection and provides a powerful tool that can be used as a readout in functional genomics screens to discover and dissect cellular pathways regulating gene expression and alternative pre-mRNA splicing events.