The newly discovered histone methyltransferase KMT9 serves as an epigenetic regulator of carcinogenesis in various cancer entities. For the first time, we investigated the presence of KMT9α in cholangiocarcinoma, the association with histologic subtypes, and its impact on survival.

A tissue microarray cohort of all CCA patients who underwent surgical resection with curative intent between 08/2005 and 12/2021 at the University Hospital Frankfurt was immunohistochemically analyzed with the KMT9α antibody. For overall survival, Kaplan-Meier curves and Cox-regression analyses were performed.

In total, 174 patients were suitable for IHC analysis. Of the patients, 35.1% (n = 61) overexpressed KMT9α. Kaplan-Meier curves revealed a median OS of 34.75 months (95% CI = 20.23-49.27 months) for all CCA patients positive for KMT9α in comparison to 54.21 months (95% CI = 41.78-66.63 months) for patients lacking KMT9α overexpression (p = 0.004). Subtype analysis revealed strong differences in KMT9α expression. Multivariate Cox regression analysis identified KMT9α as an independent risk factor for shorter OS in CCA.

This study demonstrates that a marked subset of CCA patients exhibit overexpression of KMT9α. These findings underscore the prognostic significance of KMT9α and reinforce its potential as a therapeutic target, consistent with its role in other cancer types.

Immune checkpoint inhibitors have become a mainstay of treatment in many solid organ malignancies. Alongside this has been the rapid development in the identification and targeting of oncogenic drivers. The presence of alterations in oncogenic drivers not only predicts response to target therapy but can modulate the immune microenvironment and influence response to immunotherapy. Combining immune checkpoint inhibitors with targeted agents is an attractive therapeutic option but overlapping toxicity profiles may limit the clinical use of some combinations. In addition, there is growing evidence of shared resistance mechanisms that alter the response to immunotherapy when it is used after targeted therapy. Understanding this complex interaction between oncogenic drivers, targeted therapy and response to immune checkpoint inhibitors is vital for selecting the right treatment, at the right time for the right patient. In this review, we summarise the preclinical and clinical evidence of the influence of four common oncogenic alterations on immune checkpoint inhibitor response, combination therapies, and the presence of shared resistance mechanisms. We highlight the common resistance mechanisms and the need for more randomised trials investigating both combination and sequential therapy.

Biliary tract cancers (BTCs) are classified on the basis of their anatomical origin, and the feasibility of surgical resection depends on the tumor location and extent of progression. However, for unresectable BTCs, systemic therapy has been uniformly applied. Gemcitabine and cisplatin (GC) therapy and GC-based therapies were established as the first-line standard BTC treatment. However, no highly effective second-line therapy has been established, and the prognosis remains poor, highlighting the need for further therapeutic advancements. Meanwhile, the era of precision medicine has expanded the use of genetic testing, leading to the identification of actionable molecular targets in BTC. Several targeted therapies, including FGFR inhibitors and IDH1 inhibitors, have been developed, offering new second-line treatment options and the potential for first-line use in appropriate cases. Notably, the frequency of these genetic alterations varies depending on the tumor location, demonstrating the molecular heterogeneity of BTC. Therefore, it has been recognized that a tailored treatment approach for each BTC patient may be more effective than uniform systemic therapy. Consequently, although routine genetic testing before initiating systemic treatment is currently limited by the medical environment (e.g., cost, accessibility, regional differences), it is recommended in ESMO guideline and might be increasingly advocated. However, BTC harbors a wide range of genetic alterations, and numerous targeted therapies are being developed accordingly. This review provides an overview of the reported genetic alterations in BTC, the frequencies of these alterations, and the corresponding targeted therapies, emphasizing the evolving role of precision medicine in BTC treatment.

Rationale: As the most common form of lung cancer, non-small cell lung cancer (NSCLC) is still a challenging disease. Even though molecular-targeted drugs have greatly benefited NSCLC patients, the limited number of effective targets and the emergence of drug resistance necessitate further research to identify new candidates and improve clinical outcomes. Phosphatidylinositol-3,4,5-triphosphate-dependent RAC exchange factor-2 (PREX2) is highly expressed in multiple cancer types and poses high mutation frequency in lung cancer. However, the study of PREX2 in lung cancer, especially NSCLC, is few and unclear, thus, the role of PREX2 and the regulatory mechanism of PREX2 in NSCLC is worthy of further investigation. Methods: To determine the tumor-promoting effects of PREX2 in NSCLC, we established PREX2 knockdown NSCLC cells, then assessed cell growth in vitro and in cell-derived xenograft (CDX) mouse model. Furtherly, we used the urethane-induced lung carcinogenesis mouse model to confirm the significance of PREX2 in vivo. Additionally, we identified AHCYL1 as a novel PREX2-interacting protein through pull-down assay and liquid chromatography with tandem mass spectrometry (LC-MS/MS) and investigated the mechanisms of PREX2 GEF activity regulated by AHCYL1 using various molecular biology assays, including western blotting, in vitro GEF assay and active RAC1 pull-down assay. Results: Our study suggests that PREX2 and AHCYL1 both promote NSCLC cell growth and proves that AHCYL1 enhances the GEF activity of PREX2 by alleviating the mutual inhibition between PREX2 and PTEN. Consequently, AHCYL1 intensifies the tumor-promoting effects of PREX2 in NSCLC. Conclusion: Overall, our results indicate that PREX2 and AHCYL1 promote lung cancer development and reveal a novel regulatory mechanism of PREX2 GEF activity by AHCYL1, which will contribute to the understanding of NSCLC pathogenesis and offer new targets and strategies for the diagnosis and treatment of NSCLC.

Translocations involving FGFR2 gene fusions are common in cholangiocarcinoma and predict response to FGFR kinase inhibitors. However, response rates and durability are limited due to the emergence of resistance, typically involving FGFR2 kinase domain mutations, and to suboptimal dosing, relating to drug adverse effects. Here, we develop biparatopic antibodies targeting the FGFR2 extracellular domain (ECD) as candidate therapeutics. Biparatopic antibodies can overcome drawbacks of bivalent monospecific antibodies, which often show poor inhibitory or even agonist activity against oncogenic receptors. We show that oncogenic transformation by FGFR2 fusions requires an intact ECD. Moreover, by systematically generating biparatopic antibodies targeting distinct epitope pairs in FGFR2 ECD, we identified antibodies that effectively block signaling and malignant growth driven by FGFR2 fusions. Importantly, these antibodies demonstrate efficacy in vivo, synergy with FGFR inhibitors, and activity against FGFR2 fusions harboring kinase domain mutations. Thus, we believe that biparatopic antibodies may serve as an innovative treatment option for patients with FGFR2-altered cholangiocarcinoma.

Oncogenic gene fusions occur across a broad range of cancers and are a defining feature of some cancer types. Cancers driven by gene fusion products tend to respond well to targeted therapies, where available; thus, detection of potentially targetable oncogenic fusions is necessary to select optimal treatment. Detection methods include non-sequencing methods, such as fluorescence in situ hybridization and immunohistochemistry, and sequencing methods, such as DNA- and RNA-based next-generation sequencing (NGS). While NGS is an efficient way to analyze multiple genes of interest at once, economic and technical factors may preclude its use in routine care globally, despite several guideline recommendations. The aim of this review is to present a summary of oncogenic gene fusions, with a focus on fusions that affect tyrosine kinase signaling, and to highlight the importance of testing for oncogenic fusions. We present an overview of the identification of oncogenic gene fusions and therapies approved for the treatment of cancers harboring gene fusions, and summarize data regarding treating fusion-positive cancers with no current targeted therapies and clinical studies of fusion-positive cancers. Although treatment options may be limited for patients with rare alterations, healthcare professionals should identify patients most likely to benefit from oncogenic gene fusion testing and initiate the appropriate targeted therapy to achieve optimal treatment outcomes.

Patients with intrahepatic cholangiocarcinoma (iCCA) harboring FGFR2 fusion/rearrangement benefit from targeted therapies, highlighting the need for reliable testing strategies to identify FGFR2 alterations. We assessed 226 iCCA cases using RNA-based NGS, DNA-based NGS, and break-apart FISH to evaluate the effectiveness of these methods in detecting FGFR2 fusion/rearrangement. The detection rates for FGFR2 fusion/rearrangement were 9.7% (22/226) for RNA-based NGS, 7.1% (16/226) for DNA-based NGS, and 10.2% (23/226) for FISH. Among the 26 FGFR2 fusion/rearrangement-positive cases identified by any method, only 15 (57.7%) were positive by all three techniques, yielding a concordance rate of 95.1% (215/226). RNA-based NGS confirmed oncogenic FGFR2 fusion in 81% (21/26) of positive cases and identified five novel oncogenic fusions. Thirty-five percent (6/17) of the partner genes were located on chromosome 10, with BICC1 being the most common fusion partner, while the rest were distributed across the other 9 chromosomes. FISH demonstrated a sensitivity of 95.2% and specificity of 98.5%, compared to oncogenic FGFR2 fusions confirmed by RNA-based NGS, while DNA-based NGS exhibited a sensitivity of 71.4% and specificity of 99.5%, identifying FGFR2 mutations in 4 cases. FGFR2-FISH positive cases displayed no significant heterogeneity in positive cell distribution. Oncogenic FGFR2 fusion/rearrangement was associated with small duct type iCCA, especially in cases with positive serum HBsAg and absent cholangiolocarcinoma components and peripheral liver steatosis. This study provides a comprehensive comparison of three assays for detecting FGFR2 fusion/rearrangement, along with clinicopathologic characterization of oncogenic FGFR2 fusion in iCCA.

FGFR2 fusions occur in up to 14% of patients with intrahepatic cholangiocarcinoma (iCCA) and have been considered as therapeutic target for FGFR inhibitors (FGFRi). However, response to targeted treatment may be limited due to the emergence of various resistance mechanisms. We report a case of recurrent iCCA in a 43-year-old patient with a FGFR2 fusion, who was treated with Lenvatinib. Next-generation sequencing (NGS) of tumor-normal DNA and tumor RNA under Lenvatinib treatment confirmed the FGFR2 fusion, however no further molecular resistance mutation was observed. After failure of FGFRi treatment (Lenvatinib and Infigratinib) ten months later, repeated NGS analysis revealed a new gain-of-function mutation in PIK3CA and a homozygous deletion of CDKN2A/B, potentially representing an acquired resistance mechanism. The emerging acquired resistance to FGFR inhibitor treatment has implications for subsequent treatment strategies.

The purpose of this review is to summarize the current knowledge of cholangiocarcinoma molecular biology and to suggest a framework for implementation of next-generation sequencing in all stages of liver transplantation. This is timely as recent guidelines recommend increased use of these technologies with promising results.

The main themes covered here address germline and somatic genetic alterations recently discovered in cholangiocarcinoma, particularly those associated with prognosis and treatment responses, and nascent efforts to translate these into contemporary practice in the peri-liver transplantation period.

Early efforts to translate molecular profiling to cholangiocarcinoma care demonstrate a growing number of potentially actionable alterations. Still lacking is a consensus on what biomarkers and technologies to adopt, at what scale and cost, and how to integrate them most effectively into care with the ambition of increasing the number of patients eligible for liver transplantation and improving their long-term outcomes.

Fibroblast growth factor receptor (FGFR) inhibitors have significantly improved outcomes for patients with FGFR-altered cholangiocarcinoma, leading to their regulatory approval in multiple countries. As with many targeted therapies, however, acquired resistance limits their efficacy. A comprehensive, multimodal approach is crucial to characterizing resistance patterns to FGFR inhibitors.

This study integrated data from six investigative strategies: cell-free DNA, tissue biopsy, rapid autopsy, statistical genomics, in vitro and in vivo studies, and pharmacology. We characterized the diversity, clonality, frequency, and mechanisms of acquired resistance to FGFR inhibitors in patients with FGFR-altered cholangiocarcinoma. Clinical samples were analyzed longitudinally as part of routine care across 10 institutions.

Among 138 patients evaluated, 77 met eligibility, yielding a total of 486 clinical samples. Patients with clinical benefit exhibited a significantly higher rate of FGFR2 kinase domain mutations compared with those without clinical benefit (65% versus 10%, P < 0.0001). We identified 26 distinct FGFR2 kinase domain mutations, with 63% of patients harboring multiple. While IC50 assessments indicated strong potency of pan-FGFR inhibitors against common resistance mutations, pharmacokinetic studies revealed that low clinically achievable drug concentrations may underly polyclonal resistance. Molecular brake and gatekeeper mutations predominated, with 94% of patients with FGFR2 mutations exhibiting one or both, whereas mutations at the cysteine residue targeted by covalent inhibitors were rare. Statistical genomics and functional studies demonstrated that mutation frequencies were driven by their combined effects on drug binding and kinase activity rather than intrinsic mutational processes.

Our multimodal analysis led to a model characterizing the biology of acquired resistance, informing the rational design of next-generation FGFR inhibitors. FGFR inhibitors should be small, high-affinity, and selective for specific FGFR family members. Tinengotinib, a novel small molecule inhibitor with these characteristics, exhibited preclinical and clinical activity against key resistance mutations. This integrated approach offers a blueprint for advancing drug resistance research across cancer types.

Randomized data suggest improved survival with adjuvant chemotherapy for biliary tract cancers; however, subset analyses of intrahepatic cholangiocarcinoma (IHC) show limited survival benefit. This study evaluated the impact of adjuvant chemotherapy on recurrence patterns and overall survival (OS) in patients with resected IHC.

Patients who underwent curative-intent resection for IHC were identified within a bi-institutional dataset and the National Cancer Database (NCDB). Patients were stratified by receipt of adjuvant chemotherapy. Site of first recurrence was categorized as liver only, regional, distant, or multifocal. Survival outcomes within each dataset were compared using Kaplan-Meier methods.

In the bi-institutional dataset, 347 patients underwent resection for IHC, and 149 (43%) patients received adjuvant cytotoxic chemotherapy. Recurrence was observed in 222 (64.0%) patients. OS was similar between groups (adjuvant vs. observation: 42 vs. 49 months; p = 0.13), and did not differ in patients who received capecitabine specifically (p = 0.09) or in a risk-adjusted multivariable analysis. Recurrence-free survival was worse in those who received adjuvant chemotherapy (p = 0.04), although the liver was the most common site of recurrence in both groups (0.63). A similar analysis of 1159 resected IHCs from the NCDB also demonstrated no association between adjuvant chemotherapy and OS (49 vs. 57 months; p = 0.1).

Adjuvant chemotherapy may not be associated with improved OS in IHC and did not have an impact on hepatic recurrence in this retrospective analysis. Future investigation to identify more effective adjuvant systemic regimens and/or explore the potential role of adjuvant liver-directed therapies to reduce hepatic recurrence that may improve OS for IHC is warranted.

Effective first-line treatments for unresectable intrahepatic cholangiocarcinoma (ICC) remain limited. This real-world study aimed to compare the efficacy of immune checkpoint inhibitors (ICIs) plus chemotherapy combined with or without Lenvatinib as first-line treatment in unresectable ICC patients and identify predictors of treatment response and prognosis.

In this retrospective cohort study, 58 patients with unresectable ICC received either dual therapy (ICIs plus chemotherapy) or triple therapy (ICIs plus chemotherapy and Lenvatinib) as first-line treatment. The endpoints were progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and disease control rate (DCR). Survival curve was plotted by the Kaplan-Meier method. A Cox proportional hazards model was performed to investigate risk factors of PFS and OS.

No significant differences were observed between triple therapy and dual therapy as first-line treatment for unresectable ICC patients in terms of PFS (median PFS: 10.3 vs. 11.1 months, P > 0.05) and OS (median OS: 14.0 vs. 15.0 months, P > 0.05). The ORR (39.4% vs. 30.4%) and DCR (90.9% vs. 73.9%) were comparable between the triple therapy group and dual therapy group (P > 0.05). In the multivariate analysis, tumor burden score (TBS, ≥ 8) and tumor number (≥ 2) were associated with prolonged PFS (P < 0.05), while TBS was an independent factor for OS (P < 0.05).

Triple therapy did not demonstrate any benefit on both PFS and OS compared to dual therapy as first-line treatment for patients with unresectable ICC. TBS and tumor number may guide treatment stratification.

Biliary tract cancer, carcinoma of the extrahepatic bile ducts, carcinoma of the gallbladder, ampullary carcinoma, and intrahepatic cholangiocarcinoma are often identified at advanced stages. The standard therapy for advanced biliary tract cancer has been a combination of cytotoxic agents. Globally, gemcitabine plus cisplatin has been the standard first-line regimen, whereas gemcitabine plus cisplatin plus S-1 and gemcitabine plus S-1 have also been the standard regimens in Japan. Recently, treatment strategies have been updated. As first-line systemic therapy, the addition of an immune checkpoint inhibitor, such as durvalumab or pembrolizumab, to gemcitabine plus cisplatin has been shown to prolong overall survival compared with gemcitabine plus cisplatin. These combined immunotherapies are widely used in clinical practice as internationally standard first-line regimens. Regarding second-line treatment after a gemcitabine-based regimen, fluorouracil and folinic acid plus oxaliplatin have been the standard regimen. Additionally, FGFR2 fusion gene/rearrangement, mutations of IDH1/2, KRAS, and BRAF, and overexpression of HER2 are promising therapeutic targets for which the effectiveness of each targeted therapy has been reported, at this time, as a second-line or later treatment.

Anti-claudin-18.2 (CLDN18.2) therapy was recently approved for the treatment of gastric or gastro-oesophageal junction adenocarcinoma. The aim of the present study was to investigate the expression of CLDN18.2 in cholangiocarcinoma (CCA) to determine whether there is a subgroup of patients who might also benefit from anti-CLDN18.2 therapy.

A tissue microarray (TMA) cohort of all CCA patients who underwent surgical resection with curative intent between August 2005 and December 2021 at University Hospital Frankfurt were immunohistochemically evaluated using the VENTANA® CLDN18 (43-14A) antibody. Tumour positivity for CLDN18.2 was determined as follows: ≥ 75% of tumour cells with moderate-to-strong CLDN18 membranous staining. In total, 160 patients with surgically resected CCA were suitable for immunohistochemistry (IHC) analysis. Of the patients, 13.1% (n = 21) showed moderate to strong membranous staining of VENTANA® CLDN18 antibody, while 86.9% (n = 139) were negative. Subtype analysis revealed strong differences in CLDN18 expression. Positive staining of CLDN18 could be observed in 26.5% (n = nine of 34) and 7.4% (n = seven of 95) of the perihilar (pCCA) and intrahepatic (iCCA) subgroup, respectively. CCA patients with CLDN18 expression had a more frequently intraoperative finding of distant metastasis (P = 0.002), lymph node metastasis (P = 0.008) and positive perineural invasion (Pn1) status (P = 0.022).

The present study suggests that a subset of patients with CCA exhibited a marked expression of CLDN18.2. These findings underline the need to perform a clinical study evaluating the efficacy of anti-CLDN18.2 therapy in patients suffering from CCA.

We conducted this observational study to investigate patterns of fibroblast growth factor receptor 2 (FGFR2) fusions or rearrangements, and how they relate to other characteristics of patients with unresectable advanced cholangiocarcinoma.

Patients aged 20 years or older with intrahepatic cholangiocarcinoma (ICC) or perihilar cholangiocarcinoma (PHC) had tumor samples assessed for FGFR2 fusions or rearrangements by a break-apart fluorescence in situ hybridization probe kit analyzed at a central laboratory; multivariate analyses using a logistic regression model were conducted to investigate the relationship between FGFR2 fusions or rearrangements and patients' baseline characteristics; two cut-off values (p-values of 0.15 and 0.05) were used.

Of the 453 patients observed, 25 (5.5%) had FGFR2 fusions or rearrangements, corresponding with 7.4% (23/306) of patients with ICC and 1.4% (2/144) of patients with PHC. Of 426 evaluable patients, FGFR2 fusions or rearrangements were associated with hepatitis C antibodies (odds ratio [OR] 6.901; p < 0.05); patients who had PHC versus ICC (OR 0.273; p < 0.05) or were men (OR 0.431; p < 0.15) were less likely to have FGFR2 fusions or rearrangements. Of 252 evaluable patients with ICC, FGFR2 fusions or rearrangements were associated with hepatitis C antibodies (OR 9.500; p < 0.05); patients who were men (OR 0.419; p < 0.05) or were aged ≥65 years (OR 0.406; p < 0.15) were less likely to have FGFR2 fusions or rearrangements.

This large observational study helps to characterize factors associated with FGFR2 fusions or rearrangements. Further study is warranted to explore differences in prevalence among different geographic populations and patients with PHC.

Cholangiocarcinoma (CCA) is a diverse group of epithelial malignant tumors arising from the biliary tract, characterized by high molecular heterogeneity. It is classified into intrahepatic (iCCA) and extrahepatic CCA (eCCA) based on the location of the primary tumor. CCA accounts for approximately 15% of all primary liver cancers, with iCCA comprising 10-20% of all CCAs. iCCA is especially known for its characteristic aggressiveness and refractoriness, leading to poor prognosis. Despite the increasing global incidence and mortality rates, surgery remains the only available standard treatment approach for a subset (25%) of patients with early-stage, resectable iCCA. The paucity of effective systemic medical therapies restricts therapeutic options for patients with advanced or metastatic iCCA. In the past decade, advances in the understanding of the molecular complexity of these tumors have provided fruitful insights for the identification of promising new druggable targets and the development of feasible therapeutic strategies that may improve treatment outcomes for patients with iCCA. In this review, we aim to highlight critical up-to-date studies and medicinal chemistry aspects, focusing on novel targeted approaches utilizing promising candidates for molecular targeted therapy in iCCA. These candidates include aberrations in isocitrate dehydrogenase (IDH) 1/2, fibroblast growth factor receptor (FGFR), B-Raf proto-oncogene (BRAF), neurotrophic tyrosine receptor kinase (NTRK), human epidermal growth factor receptor 2 (HER2), and programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1). Furthermore, this review provides an overview of potential inhibitors aimed at overcoming acquired drug resistance in these actionable targets for iCCA.

Somatic FGFR gene alterations (FGFRalt) may act as oncogenic drivers across several cancers. The prognostic impact of FGFRalt in solid tumors is not fully understood. We assessed the prognostic impact of FGFRalt on overall survival (OS) in a tumor-agnostic real-world cohort of patients with advanced solid tumors.

This was a retrospective, observational, comparative cohort analysis that used data from a nationwide de-identified clinico-genomic database. Patients were included if they had advanced/metastatic disease, were aged ≥ 18 years at the time of diagnosis, had evidence of genomic testing for FGFRalt, and had initiated first-line systemic therapy for their cancer. Patients without FGFR alterations (FGFRneg) were matched 3:1 with patients with FGFRalt using a combination of exact matching on tumor type and Mahalanobis-distance matching on selected clinical confounders. The primary endpoint was OS from time of initiation of first-line therapy in patients with FGFRalt versus FGFRneg. To further mitigate bias, delayed entry models and covariate-adjusted stratified Cox models were implemented.

The final cohort included 1012 patients (253 FGFRalt, 759 FGFRneg), across 30 tumor types. There were no significant differences in real-world OS from first-line therapy between FGFRalt and FGFRneg groups (hazard ratio 0.97; p = 0.78). Median OS from initiation of first-line therapy was 1.13 years (95% confidence interval [CI] 0.92-1.52) and 1.01 years (0.89-1.15) for the FGFRalt and FGFRneg groups, respectively.

In this matched-cohort real-world analysis, presence of FGFRalt had no impact on the prognosis of patients with advanced solid tumors receiving standard-of-care treatment.

FGFR2 fusion has become a promising therapeutic target in iCCAs; however, the procedure for screening FGFR2 fusion has not been conventionally developed.

FGFR2 fusion was identified using DNA + RNA-based NGS and FISH, and the concordance between DNA + RNA-based NGS, FISH, and IHC was compared.

FGFR2 fusions were detected in 9 out of 76 iCCAs (11.8%). The consistency of FISH and DNA + RNA-based NGS for FGFR2 fusions was high (κ value = 0.867, P = 0.001), while the consistency of IHC and DNA + RNA-based NGS was lower (κ value = 0.464, P = 0.072). All nine FGFR2 fusion-positive iCCAs were MSS with a median TMB of 2.1 mut/Mb, and only one had a CPS (PD-L1) above 5. Two FGFR2 fusion-positive iCCA patients were treated with and benefited from FGFR inhibitor therapy.

FGFR2 fusion should be assessed for advanced iCCA patients. We recommend DNA + RNA-based NGS as the preferred option to supply all possible therapeutic targets. FISH should be preferred if the tumor sample is insufficient for NGS or if the patient is inclined to receive FGFR inhibitors promptly. Although IHC is not the preferred method to identify FGFR2 fusion, it might be used as preliminary screening for FGFR2 alterations if the hospital cannot offer NGS or FISH, and the results need to be validated before FGFR2 inhibitors treatment.

Cholangiocarcinoma (CCA) remains a devastating malignancy and a significant challenge to treat. The majority of CCA patients are diagnosed at an advanced stage, making the disease incurable in most cases. The advent of high-throughput genetic sequencing has significantly improved our understanding of the molecular biology underpinning cancer. The identification of 'druggable' genetic aberrations and the development of novel targeted therapies against them is opening up new treatment strategies. Currently, 3 targeted therapies are approved for use in CCA; Ivosidenib in patients with IDH1 mutations and Infigratinib/Pemigatinib in those with FGFR2 fusions. As our understanding of the biology underpinning CCA continues to improve it is highly likely that additional targeted therapies will become available in the near future. This is important, as it is thought up to 40 % of CCA patients harbour a potentially actionable mutation. In this review we provide an overview of the molecular pathogenesis of CCA and highlight currently available and potential future targeted treatments.

Intrahepatic cholangiocarcinoma is an aggressive malignancy with rising incidence and poor outcomes. This review examines recent advancements in locoregional therapies for unresectable intrahepatic cholangiocarcinoma, focusing on external beam radiotherapy, transarterial radioembolization (TARE), hepatic artery infusion pump (HAIP) chemotherapy, and liver transplantation. Stereotactic body radiation therapy and proton beam therapy have shown promise in achieving local control and improving survival. TARE, with personalized dosimetry, has demonstrated encouraging results in select patient populations. HAIP chemotherapy, primarily studied using floxuridine, has yielded impressive survival outcomes in phase II trials. Liver transplantation, once contraindicated, is now being reconsidered for carefully selected patients with localized disease. While these locoregional approaches show potential, randomized controlled trials comparing them to standard systemic therapy are lacking. Patient selection remains crucial, with factors such as liver function, tumor burden, and molecular profile influencing treatment decisions. Ongoing research aims to optimize treatment sequencing, explore combination strategies with systemic therapies, and refine phenotype identification and patient selection criteria. As the landscape of intrahepatic cholangiocarcinoma management evolves, a multidisciplinary approach is essential to tailor treatment strategies and improve outcomes for patients with this challenging disease.

Recent research indicates a role of gut microbiota in development and progression of life-threatening diseases such as cancer. Carcinomas of the biliary ducts, the so-called cholangiocarcinomas, are known for their aggressive tumor biology, implying poor prognosis of affected patients. An impact of the gut microbiota on cholangiocarcinoma development and progression is plausible due to the enterohepatic circulation and is therefore the subject of scientific debate, however evidence is still lacking. This review aimed to discuss the suitability of complex cell culture models to investigate the role of gut microbiota in cholangiocarcinoma progression.

Clinical research in this area is challenging due to poor comparability of patients and feasibility reasons, which is why translational models are needed to understand the basis of tumor progression in cholangiocarcinoma. A promising approach to investigate the influence of gut microbiota could be an organoid model. Organoids are 3D cell models cultivated in a modifiable and controlled condition, which can be grown from tumor tissue. 3D cell models are able to imitate physiological and pathological processes in the human body and thus contribute to a better understanding of health and disease.

The use of complex cell cultures such as organoids and organoid co-cultures might be powerful and valuable tools to study not only the growth behavior and growth of cholangiocarcinoma cells, but also the interaction with the tumor microenvironment and with components of the gut microbiota.

Fibroblast growth factor receptors (FGFRs) are a highly conserved family of transmembrane receptor tyrosine kinases with multiple roles in the regulation of key cellular processes. Specific FGFR mutations have been observed in several types of cancers, including gastric carcinoma and cholangiocarcinoma. Dose escalation data of 24 Japanese patients with solid tumors treated with Tasurgratinib (previously known as E7090), a potent, selective FGFR1-3 inhibitor, was reported in a phase I, first-in-human, single-center study. Based on the safety, pharmacokinetic, and pharmacodynamic profiles observed in this study, the recommended dose of 140 mg once daily was selected for the expansion part (Part 2), a multicenter expansion of the dose-finding study restricted to patients with tumors harboring FGFR gene alterations. Safety and preliminary efficacy were assessed in Part 2. Pharmacodynamic pharmacogenomic markers (serum phosphate, FGF23, and 1,25-(OH)2-vitamin D, circulating tumor DNA) and pharmacokinetic profiles were also evaluated. A total of 16 patients were enrolled in Part 2, six with cholangiocarcinoma and 10 with gastric cancer. The most common treatment-emergent adverse events were hyperphosphatemia, palmar-plantar erythrodysesthesia syndrome, and paronychia. Five partial responses (83.3%) in cholangiocarcinoma patients and one partial response (11.1%) in gastric cancer patients were observed; median progression-free survival was 8.26 months (95% confidence interval [CI] 3.84, not evaluable [NE]) and 3.25 months (95% CI 0.95, 4.86), and overall survival was 22.49 months (95% CI 6.37, NE) and 4.27 months (95% CI 2.23, 7.95), respectively, in the two groups. In conclusion, Tasurgratinib 140 mg has a tolerable safety profile with good clinical efficacy in patients with cholangiocarcinoma harboring FGFR2 gene rearrangements.

Precision medicine has emerged as a cornerstone in cancer treatment revolutionizing our approach across malignancies. Molecular profiling of biliary tract cancers (BTCs) has changed the treatment landscape positively by prolonging survival in an aggressively fatal malignancy in its advanced stages. The acquisition of tissue tumor DNA for genomic analysis in BTC is often anatomically challenging, limited by quantity and quality. In response, ctDNA has emerged as a noninvasive means of molecular profiling. The utility of both plasma and bile ctDNA has been explored in several studies demonstrating the high mutation detection rates and the ability to isolate targetable mutations when present. In addition, the concordance between plasma and tissue DNA provides validity in utilizing ctDNA results to infer treatment decisions. Analysis of ctDNA in BTC has also provided prognostic information and facilitated evaluation of clonal evolution with ease of serial measurements. Insight into novel mechanisms of resistance to targeted therapies are being uncovered in ctDNA. As research endeavors continue to deepen our understanding in the field particularly in the space of ctDNA surveillance after curative intent, the tremendous progress made so far has enabled integration of ctDNA into the clinical practice of BTCs.

Fibroblast growth factors (FGFs) have diverse functions in the regulation of cell proliferation and differentiation in development, tissue maintenance, wound repair, and angiogenesis. The goal of this review paper is to (i) deliberate on the role of FGFs and FGF receptors (FGFRs) in different cancers, (ii) present advances in FGF-targeted cancer therapies, and (iii) explore cell signaling mechanisms that explain how FGF expression becomes dysregulated during cancer development. FGF is often mutated and overexpressed in cancer and the different FGF and FGFR isoforms have unique expression patterns and distinct roles in different cancers. Among the FGF members, the FGF 15/19 subfamily is particularly interesting because of its unique protein structure and role in endocrine function. The abnormal expression of FGFs in different cancer types (breast, colorectal, hepatobiliary, bronchogenic, and others) is examined and correlated with patient prognosis. The classification of FGF ligands based on their mode of action, whether autocrine, paracrine, endocrine, or intracrine, is illustrated, and an analysis of the binding specificity of FGFs to FGFRs is also provided. Moreover, the latest advances in cancer therapeutic strategies involving small molecules, ligand traps, and monoclonal antibody-based FGF inhibitors are presented. Lastly, we discuss how the dysregulation of FGF and FGFR expression affects FGF signaling and its role in cancer development.

Increasing evidence highlights that fibroblast growth factor receptor 2 (FGFR2) fusion/rearrangement shows important therapeutic value for patients with intrahepatic cholangiocarcinoma (ICC). This study aims to explore the association of FGFR2 status with the prognosis and immune cell infiltration profiles of patients with ICC. A total of 226 ICC tissue samples from patients who received surgery at the Department of Liver Surgery at Zhongshan Hospital, Fudan University, were collected retrospectively and assigned to a primary cohort (n = 152) and validation cohort (n = 74) group. Fluorescence in situ hybridization was performed to determine FGFR2 status. Multiplex immunofluorescence (mIF) staining and immunohistochemistry were performed to identify immune cells. Thirty-two (14.2%) ICC tissues presented with FGFR2 fusion/rearrangement. FGFR2 fusion/rearrangement was associated with low levels of carcinoembryonic antigen (CEA, P = .026) and gamma glutamyl transferase (γ-GGT, P = .003), low TNM (P = .012), CNLC (P = .008) staging as well as low tumor cell differentiation (P = .016). Multivariate COX regression analyses revealed that FGFR2 fusion/rearrangement was an independent protective factor for both overall survival (OS) and relapse-free survival in patients with ICC. Furthermore, correlation analysis revealed that an FGFR2 fusion/rearrangement was associated with low levels of Tregs and N2 neutrophils and high levels of N1 neutrophils infiltrating into tumors but not with CD8+ T-cell or macrophage tumor infiltration. FGFR2 fusion/rearrangement may exert a profound impact on the prognosis of ICC patients and reprogram the tumor microenvironment to be an immune-activated state. FGFR2 status may be used for ICC prognostic stratification and as an immunotherapeutic target in patients with ICC.

Cholangiocarcinoma is the rare and aggressive tumor with poor prognosis and limited therapeutic options. Recently, there have been promising developments in molecular targeted therapies for patients following the progression of first-line chemotherapy and immunotherapy combinations. Dysregulation of fibroblast Growth Factor Receptor (FGFR) signaling is significantly associated with tumorigenesis of intrahepatic cholangiocarcinoma and has been identified as a targetable alteration. This was possible through the discovery of crucial insights into the biochemical mechanisms and pathophysiology of the FGFR pathway.

This review summarizes the current state of FGFR targeted therapies, mechanisms of resistance, and future directions for FGFR-targeted therapies in patients with cholangiocarcinoma.

Currently, pemigatinib and futibatinib are FDA approved FGFR-targeted therapies that have demonstrated remarkable responses. However, there is still a significant proportion of patients whose disease remains intrinsically resistant to treatment and most patients eventually develop secondary resistance after an initial response. Additionally, unique side effects of FGFR inhibitors may limit their efficacy in clinical practice and can have detrimental effects on quality of life. Several novel FGFR inhibitors are currently being investigated to overcome resistance mechanisms and reduce toxicities.

The fibroblast growth factor receptor (FGFR) is a crucial receptor tyrosine kinase involved in essential biological processes, including growth, development, and tissue repair. However, FGFR gene mutations, including amplification, fusion, and mutation, can disrupt epigenetics, transcriptional regulation, and tumor microenvironment interactions, leading to cancer development. Targeting these kinase mutations with small molecule drugs or antibodies has shown clinical benefits. For example, erdafitinib is approved for treating locally advanced or metastatic urothelial cancer patients with FGFR2/FGFR3 mutations, and pemigatinib is approved for treating cholangiocarcinoma with FGFR2 fusion/rearrangement. Effective screening of FGFR variant patients is crucial for the clinical application of FGFR inhibitors. Various detection methods, such as polymerase chain reaction, next-generation sequencing, fluorescence in situ hybridization, and immunohistochemistry, are available, and their selection should be based on diagnostic and treatment decision-making needs. Our developed expert consensus aims to standardize the diagnosis and treatment process for FGFR gene mutations and facilitate the practical application of FGFR inhibitors in clinical practice.