Isocitrate dehydrogenase 1 and 2 mutations in cholangiocarcinoma

Pharmacokinetics/pharmacodynamics of ivosidenib in advanced IDH1-mutant cholangiocarcinoma: findings from the phase III ClarIDHy study

PURPOSE

Report pharmacokinetic (PK)/pharmacodynamic (PD) findings from the phase III ClarIDHy study and any association between PK/PD parameters and treatment outcomes in this population.

METHODS

Patients with mutant isocitrate dehydrogenase 1 (mIDH1) advanced cholangiocarcinoma were randomized at a 2:1 ratio to receive ivosidenib or matched placebo. Crossover from placebo to ivosidenib was permitted at radiographic disease progression. Blood samples for PK/PD analyses, a secondary endpoint, were collected pre-dose and up to 4 h post-dose on day (D) 1 of cycles (C) 1 - 2, pre-dose and 2 h post-dose on D15 of C1 - 2, and pre-dose on D1 from C3 onwards. Plasma ivosidenib and D-2-hydroxyglutarate (2-HG) were measured using liquid chromatography-tandem mass spectrometry. All clinical responses were centrally reviewed previously.

RESULTS

PK/PD analysis was available for samples from 156 ivosidenib-treated patients. Ivosidenib was absorbed rapidly following single and multiple oral doses (time of maximum observed plasma concentration [Tmax] of 2.63 and 2.07 h, respectively). Ivosidenib exposure was higher at C2D1 than after a single dose, with low accumulation. In ivosidenib-treated patients, mean plasma 2-HG concentration was reduced from 1108 ng/mL at baseline to 97.7 ng/mL at C2D1, close to levels previously observed in healthy individuals. An average 2-HG inhibition of 75.0% was observed at steady state. No plasma 2-HG decreases were seen with placebo. Plasma 2-HG reductions were observed in ivosidenib-treated patients irrespective of best overall response (progressive disease, or partial response and stable disease).

CONCLUSION

Once-daily ivosidenib 500 mg has a favorable PK/PD profile, attesting the 2-HG reduction mechanism of action and, thus, positive outcomes in treated patients with advanced mIDH1 cholangiocarcinoma.

CLINICAL TRIAL REGISTRATION

NCT02989857 Registered February 20, 2017.

How Molecular Discoveries Have Changed Liver Tumor Pathology: A Brief Review

CONTEXT

Recent molecular discoveries have led to improved understanding of tumor biology and the development of new diagnostic assays.

OBJECTIVE

To review primarily 3 examples of liver tumors and to briefly illustrate how recent molecular discoveries have altered clinical liver pathology practice.

DATA SOURCES

First, we will discuss fibrolamellar carcinoma, which will be the main focus of discussion, as an example for new diagnostic tests that have been developed as a result of molecular discoveries. Additional information on the role of molecular diagnostics in hepatocellular adenoma and hepatocellular carcinoma will be provided. Second, we will use the example of epithelioid hemangioendothelioma as an example of how new diagnostic tools, based on molecular discoveries, may support improved prognostication. Finally, we will use the example of intrahepatic cholangiocarcinoma as an example of a liver tumor where new molecular discoveries have identified tractable therapeutic targets and led to new effective therapies. This portion of the manuscript will also include a description of the anatomic and molecular differences between intrahepatic, hilar, and extrahepatic cholangiocarcinoma.

CONCLUSIONS

Fueled by molecular discoveries, new and better diagnostic tests and therapeutic targets have improved clinical care in patients affected by liver tumors.

Current and Future Therapeutic Targets for Directed Molecular Therapies in Cholangiocarcinoma

We conducted a comprehensive review of the current literature of published data, clinical trials (MEDLINE; ncbi.pubmed.com), congress contributions (asco.org; esmo.org), and active recruiting clinical trains (clinicaltrial.gov) on targeted therapies in cholangiocarcinoma. Palliative treatment regimens were analyzed as well as preoperative and perioperative treatment options. We summarized the current knowledge for each mutation and molecular pathway that is or has been under clinical evaluation and discussed the results on the background of current treatment guidelines. We established and recommended targeted treatment options that already exist for second-line settings, including IDH-, BRAF-, and NTRK-mutated tumors, as well as for FGFR2 fusion, HER2/neu-overexpression, and microsatellite instable tumors. Other options for targeted treatment include EGFR- or VEGF-dependent pathways, which are known to be overexpressed or dysregulated in this cancer type and are currently under clinical investigation. Targeted therapy in CCA is a hallmark of individualized medicine as these therapies aim to specifically block pathways that promote cancer cell growth and survival, leading to tumor shrinkage and improved patient outcomes based on the molecular profile of the tumor.

Resolving Challenges in Detection and Quantification of D-2-hydroxyglutarate and L-2-hydroxyglutarate via LC/MS

D-2-Hydroxyglutarate and L-2-Hydroxyglutarate (D-2HG/L-2HG) are typically metabolites of non-specific enzymatic reactions that are kept in check by the housekeeping enzymes, D-2HG /L-2HG dehydrogenase (D-2HGDH/L-2HGDH). In certain disease states, such as D-2HG or L-2HG aciduria and cancers, accumulation of these biomarkers interferes with oxoglutarate-dependent enzymes that regulate bioenergetic metabolism, histone methylation, post-translational modification, protein expression and others. D-2HG has a complex role in tumorigenesis that drives metabolomics investigations. Meanwhile, L-2HG is produced by non-specific action of malate dehydrogenase and lactate dehydrogenase under acidic or hypoxic environments. Characterization of divergent effects of D-2HG/L-2HG on the activity of specific enzymes in diseased metabolism depends on their accurate quantification via mass spectrometry. Despite advancements in high-resolution quadrupole time-of-flight mass spectrometry (HR-QTOF-MS), challenges are typically encountered when attempting to resolve of isobaric and isomeric metabolites such as D-2HG/L-2HG for quantitative analysis. Herein, available D-2HG/L-2HG derivatization and liquid chromatography (LC) MS quantification methods were examined. The outcome led to the development of a robust, high-throughput HR-QTOF-LC/MS approach that permits concomitant quantification of the D-2HG and L-2HG enantiomers with the benefit to quantify the dysregulation of other intermediates within interconnecting pathways. Calibration curve was obtained over the linear range of 0.8-104 nmol/mL with r 2 ≥ 0.995 for each enantiomer. The LC/MS-based assay had an overall precision with intra-day CV % ≤ 8.0 and inter-day CV % ≤ 6.3 across the quality control level for commercial standard and pooled biological samples; relative error % ≤ 2.7 for accuracy; and resolution, R s = 1.6 between 2HG enantiomers (m/z 147.030), D-2HG and L-2HG (at retention time of 5.82 min and 4.75 min, respectively) following chiral derivatization with diacetyl-L-tartaric anhydride (DATAN). Our methodology was applied to disease relevant samples to illustrate the implications of proper enantioselective quantification of both D-2HG and L-2HG. The stability of the method allows scaling to large cohorts of clinical samples in the future.

Molecular biology of cholangiocarcinoma and its implications for targeted therapy in patient management

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.

Recent Advances in Systemic Therapy for Advanced Intrahepatic Cholangiocarcinoma

Background

The incidence of intrahepatic cholangiocarcinoma (IHCCA) is rising around the world. The disease is becoming a major global health issue. Conventionally, most patients with cholangiocarcinoma present with advanced disease and systemic therapy is the mainstay of treatment. This review discusses recent advances in systemic treatments for patients with IHCCA.

Summary

The addition of durvalumab to a gemcitabine plus cisplatin regimen has significantly improved overall survival in the phase 3 TOPAZ-1 trial and is currently recommended as a standard first-line treatment. The phase 3 ABC-06 and phase 2b NIFTY trials have shown the benefit of second-line fluoropyrimidine plus oxaliplatin, and fluoropyrimidine plus nanoliposomal irinotecan, respectively. They have provided a treatment option for patients without actionable alterations who progressed to first-line therapy. For patients with actionable genomic alterations, including FGFR2 rearrangement, IDH1 mutation, BRAF mutation, and ERBB2 amplification, targeted agents have shown encouraging efficacy in several phase 2-3 trials, and are recommended as subsequent treatments. Immune checkpoint inhibitors are being investigated for the treatment of previously treated patients, although only a small proportion of patients showed durable responses.

Key Messages

Recent advances in systemic treatments have improved clinical outcomes in patients with advanced IHCCA. However, most patients eventually show resistance to the treatment, and tumor progression occurs within a year. Indeed, there should be further efforts to improve the outcomes of patients with advanced IHCCA.

A personalized medicine approach identifies enasidenib as an efficient treatment for IDH2 mutant chondrosarcoma

BACKGROUND

Sarcomas represent an extensive group of malignant diseases affecting mesodermal tissues. Among sarcomas, the clinical management of chondrosarcomas remains a complex challenge, as high-grade tumours do not respond to current therapies. Mutations in the isocitrate dehydrogenase (IDH) 1 and 2 genes are among the most common mutations detected in chondrosarcomas and may represent a therapeutic opportunity. The presence of mutated IDH (mIDH) enzymes results in the accumulation of the oncometabolite 2-HG leading to molecular alterations that contribute to drive tumour growth.

METHODS

We developed a personalized medicine strategy based on the targeted NGS/Sanger sequencing of sarcoma samples (n = 6) and the use of matched patient-derived cell lines as a drug-testing platform. The anti-tumour potential of IDH mutations found in two chondrosarcoma cases was analysed in vitro, in vivo and molecularly (transcriptomic and DNA methylation analyses).

FINDINGS

We treated several chondrosarcoma models with specific mIDH1/2 inhibitors. Among these treatments, only the mIDH2 inhibitor enasidenib was able to decrease 2-HG levels and efficiently reduce the viability of mIDH2 chondrosarcoma cells. Importantly, oral administration of enasidenib in xenografted mice resulted in a complete abrogation of tumour growth. Enasidenib induced a profound remodelling of the transcriptomic landscape not associated to changes in the 5 mC methylation levels and its anti-tumour effects were associated with the repression of proliferative pathways such as those controlled by E2F factors.

INTERPRETATION

Overall, this work provides preclinical evidence for the use of enasidenib to treat mIDH2 chondrosarcomas.

FUNDING

Supported by the Spanish Research Agency/FEDER (grants PID2022-142020OB-I00; PID2019-106666RB-I00), the ISC III/FEDER (PI20CIII/00020; DTS18CIII/00005; CB16/12/00390; CB06/07/1009; CB19/07/00057); the GEIS group (GEIS-62); and the PCTI (Asturias)/FEDER (IDI/2021/000027).

Practical guidelines for molecular testing of cholangiocarcinoma in clinical practice: Italian experts' position paper

Biliary tract cancers (BTCs) represent a spectrum of malignancies associated with a dismal prognosis. Recent genomic profiling studies have provided a deeper understanding of the complex and heterogenous molecular landscape of BTCs, identifying several actionable genetic alterations, and expanding treatment options. Due to the high number and complexity of genetic alterations which require testing, next-generation sequencing (NGS) is currently the preferred approach over conventional methods (i.e., immunohistochemistry, fluorescence in-situ hybridization and PCR) for molecular profiling of BTCs and should be performed upfront in all BTC patients. However, BTC sampling often yields low tumor cellularity tissue, hampering NGS analysis. Future perspectives to overcome this obstacle include liquid biopsy and optimization of biopsy protocols. In this position paper, the authors discuss the current histopathologic, molecular, and therapeutic landscape of BTCs, provide a critical overview of the available testing methods for molecular diagnostics, and propose a practical diagnostic algorithm for molecular testing of BTC samples.

Classification of Intrahepatic Cholangiocarcinoma into Perihilar Versus Peripheral Subtype

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) constitutes a group of heterogeneous malignancies within the liver. We sought to subtype ICC based on anatomical origin of tumors, as well as propose modifications of the current classification system.

METHODS

Patients undergoing curative-intent resection for ICC, hilar cholangiocarcinoma (CCA), or hepatocellular carcinoma (HCC) were identified from three international multi-institutional consortia of databases. Clinicopathological characteristics and survival outcomes were assessed.

RESULTS

Among 1264 patients with ICC, 1066 (84.3%) were classified as ICC-peripheral subtype, whereas 198 (15.7%) were categorized as ICC-perihilar subtype. Compared with ICC-peripheral subtype, ICC-perihilar subtype was more often associated with aggressive tumor characteristics, including a higher incidence of nodal metastasis, macro- and microvascular invasion, perineural invasion, as well as worse overall survival (OS) (median: ICC-perihilar 19.8 vs. ICC-peripheral 37.1 months; p < 0.001) and disease-free survival (DFS) (median: ICC-perihilar 12.8 vs. ICC-peripheral 15.2 months; p = 0.019). ICC-perihilar subtype and hilar CCA had comparable OS (19.8 vs. 21.4 months; p = 0.581) and DFS (12.8 vs. 16.8 months; p = 0.140). ICC-peripheral subtype tumors were associated with more advanced tumor features, as well as worse survival outcomes versus HCC (OS, median: ICC-peripheral 37.1 vs. HCC 74.3 months; p < 0.001; DFS, median: ICC-peripheral 15.2 vs. HCC 45.5 months; p < 0.001).

CONCLUSIONS

ICC should be classified as ICC-perihilar and ICC-peripheral subtype based on distinct clinicopathological features and survival outcomes. ICC-perihilar subtype behaved more like carcinoma of the bile duct (i.e., hilar CCA), whereas ICC-peripheral subtype had features and a prognosis more akin to a primary liver malignancy.

Precision therapy for intrahepatic cholangiocarcinoma: A case report on adjuvant treatment in a recurrent patient after surgery and literature review

A 37-year-old female patient was diagnosed with intrahepatic cholangiocarcinoma (ICC), with the lesion located in the right lobe of the liver. Despite radical resection, postoperative adjuvant chemotherapy and a combination of adjuvant chemotherapy and immunotherapy, the patient continued to experience multiple instances of intrahepatic tumor metastases. Furthermore, the patient exhibited significant adverse reactions to systemic chemotherapy and had poor treatment tolerance. Guidance from paraffin section fluorescence in situ hybridization gene sequencing was used to select a combination of immunotherapy and targeted therapy treatments with programmed cell death 1 (PD-1)/PD-1 ligand 1 antibody durvalumab and the targeted drug pemigatinib. The patient tolerated the treatment and has continued to survive for 28 months. According to imaging evaluations, the lesions continued to decrease, with some disappearing completely. The tumor marker carbohydrate antigen 19-9 remained normal for >9 weeks during the treatment. This report described the patient's treatment process in detail and briefly reviewed relevant literature on the treatment progress of postoperative patients with ICC.

Neoadjuvant and adjuvant therapy for biliary tract cancer: Advances and limitations

Biliary tract cancers (BTC) are a rare and aggressive consortium of malignancies, consisting of intrahepatic cholangiocarcinoma, extrahepatic cholangiocarcinoma, and gallbladder carcinoma. While most patients present with metastatic disease, a minority of patients with BTC are eligible for curative surgical resection at the time of presentation. However, these patients have poor 5-year overall survival rates and high rates of recurrence, necessitating the improvement of the neoadjuvant and adjuvant treatment of BTC. In this review, we assess the neoadjuvant and adjuvant clinical trials for the treatment of BTC and discuss the challenges and limitations of clinical trials, as well as future directions for the treatment of BTC.

Molecular Profile of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a relatively uncommon but highly aggressive primary liver cancer that originates within the liver. The aim of this study is to review the molecular profile of intrahepatic cholangiocarcinoma and its implications for prognostication and decision-making. This comprehensive characterization of ICC tumors sheds light on the disease's underlying biology and offers a foundation for more personalized treatment strategies. This is a narrative review of the prognostic and therapeutic role of the molecular profile of ICC. Knowing the molecular profile of tumors helps determine prognosis and support certain target therapies. The molecular panel in ICC helps to select patients for specific therapies, predict treatment responses, and monitor treatment responses. Precision medicine in ICC can promote improvement in prognosis and reduce unnecessary toxicity and might have a significant role in the management of ICC in the following years. The main mutations in ICC are in tumor protein p53 (TP53), Kirsten rat sarcoma virus (KRAS), isocitrate dehydrogenase 1 (IDH1), and AT-rich interactive domain-containing protein 1A (ARID1A). The rate of mutations varies significantly for each population. Targeting TP53 and KRAS is challenging due to the natural characteristics of these genes. Different stages of clinical studies have shown encouraging results with inhibitors of mutated IDH1 and target therapy for ARID1A downstream effectors. Fibroblast growth factor receptor 2 (FGFR2) fusions are an important target in patients with ICC. Immune checkpoint blockade can be applied to a small percentage of ICC patients. Molecular profiling in ICC represents a groundbreaking approach to understanding and managing this complex liver cancer. As our comprehension of ICC's molecular intricacies continues to expand, so does the potential for offering patients more precise and effective treatments. The integration of molecular profiling into clinical practice signifies the dawn of a new era in ICC care, emphasizing personalized medicine in the ongoing battle against this malignancy.

Molecular targeted and systemic therapy for intrahepatic cholangiocarcinoma: a multi-disciplinary approach

Most patients with intrahepatic cholangiocarcinoma (ICC) are diagnosed with advanced disease. For individuals with resectable tumors, R0 resection with lymphadenectomy is the best potentially curative-intent treatment. After resection, adjuvant therapy with capecitabine is the current standard of care. For patients with unresectable or distant metastatic disease, doublet chemotherapy with gemcitabine and cisplatin is the most utilized first-line regimen, but recent studies using triplet regimens and even the addition of immunotherapy have begun to shift the paradigm of systemic therapy. Molecular therapies have recently received US FDA approval for second-line treatment for patients harboring actionable genomic alterations. This review focuses on the multidisciplinary approach to the treatment of ICC with an emphasis on molecular targeted and systemic therapy.

Research trends of targeted therapy for cholangiocarcinoma from 2003 to 2022: a bibliometric and visual analysis

In the past 20 years, targeted therapy for cholangiocarcinoma has attracted certain attention. There is a significant upward in papers focusing on this field. In this study, we used bibliometric and visual methods to explore the current status and future directions in cholangiocarcinoma-targeted therapy research. A total of 1057 papers published in English from 2003 to 2022 were extracted from the Web of Science Core Collection SCI-expanded database. Furthermore, Citespace, Vosviewer, and Excel 2016 were utilized to conduct bibliometric and visual analysis. The volume of annual publications has steadily increased over the past two decades. The USA has published the largest number of publications, and the Mayo Clinic acted as the dominant institution. Cancers, Frontiers in Oncology, and Hepatology were the prolific resources in this research field. Moreover, the co-cited reference analysis uncovered the landmark paper in this field. With regard to research hotspots and frontiers, the burst keywords analysis showed that growth factor receptors and pathogenesis might become the hot topics of future research. To sum up, our study displays the current research status and future directions in the targeted therapy for cholangiocarcinoma. More comprehensive and in-depth investigations should focus on critical genetic mutations and their molecular mechanisms to prompt the molecular-targeted therapy.

EASL-ILCA Clinical Practice Guidelines on the management of intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) develops inside the liver, between bile ductules and the second-order bile ducts. It is the second most frequent primary liver cancer after hepatocellular carcinoma, and its global incidence is increasing. It is associated with an alarming mortality rate owing to its silent presentation (often leading to late diagnosis), highly aggressive nature and resistance to treatment. Early diagnosis, molecular characterisation, accurate staging and personalised multidisciplinary treatments represent current challenges for researchers and physicians. Unfortunately, these challenges are beset by the high heterogeneity of iCCA at the clinical, genomic, epigenetic and molecular levels, very often precluding successful management. Nonetheless, in the last few years, progress has been made in molecular characterisation, surgical management, and targeted therapy. Recent advances together with the awareness that iCCA represents a distinct entity amongst the CCA family, led the ILCA and EASL governing boards to commission international experts to draft dedicated evidence-based guidelines for physicians involved in the diagnostic, prognostic, and therapeutic management of iCCA.

Mutant IDH in Gliomas: Role in Cancer and Treatment Options

Altered metabolism is a common feature of many cancers and, in some cases, is a consequence of mutation in metabolic genes, such as the ones involved in the TCA cycle. Isocitrate dehydrogenase (IDH) is mutated in many gliomas and other cancers. Physiologically, IDH converts isocitrate to α-ketoglutarate (α-KG), but when mutated, IDH reduces α-KG to D2-hydroxyglutarate (D2-HG). D2-HG accumulates at elevated levels in IDH mutant tumours, and in the last decade, a massive effort has been made to develop small inhibitors targeting mutant IDH. In this review, we summarise the current knowledge about the cellular and molecular consequences of IDH mutations and the therapeutic approaches developed to target IDH mutant tumours, focusing on gliomas.

Updates in the use of targeted therapies for the treatment of cholangiocarcinoma

OBJECTIVE

Many patients with cholangiocarcinoma (CCA) are not surgical candidates, and the survival benefit of chemotherapy is less than 12 months. Several mutations and mutational clusters have recently been identified in CCA, some of which are pharmacologically targetable. The emergence of targeted therapies has significantly altered the treatment landscape of CCA and improved the prognosis for advanced or metastatic CCA. The purpose of this review is to describe past and current treatment strategies of CCA with a focus on FDA-approved targeted therapies.

DATA SOURCES

A systematic evaluation of all FDA-approved targeted treatments for CCA through October 2022 was conducted. Information related to pharmacology, clinical efficacy, and safety was gathered from the package insert, and clinical trial data.

DATA SUMMARY

As of the writing of this review, four targeted agents are FDA approved for the treatment of locally advanced or metastatic CCA. These agents include the IDH1 inhibitor ivosidenib and the FGFR2 inhibitors pemigatinib, infigratinib, and futibatinib. Collectively, these agents have provided additional treatment options for select patients with previously treated locally advanced or unresectable CCA. These agents have also contributed to the development of other targeted therapies for the treatment of CCA and have opened the door for the exploration of novel treatment combinations such as chemotherapy and immunotherapy, which have recently become a front-line treatment option.

CONCLUSIONS

Four targeted small molecule agents have emerged as effective therapies in the second-line setting for CCA, which has immensely changed the treatment landscape and directly led to further investigation of targeted agents and immunotherapy as treatment for CCA.

Unraveling the heterogeneity of cholangiocarcinoma and identifying biomarkers and therapeutic strategies with single-cell sequencing technology

Cholangiocarcinoma (CCA) is a common malignant tumor of the biliary tract that carries a high burden of morbidity and a poor prognosis. Due to the lack of precise diagnostic methods, many patients are often diagnosed at advanced stages of the disease. The current treatment options available are of varying efficacy, underscoring the urgency for the discovery of more effective biomarkers for early diagnosis and improved treatment. Recently, single-cell sequencing (SCS) technology has gained popularity in cancer research. This technology has the ability to analyze tumor tissues at the single-cell level, thus providing insights into the genomics and epigenetics of tumor cells. It also serves as a practical approach to study the mechanisms of cancer progression and to explore therapeutic strategies. In this review, we aim to assess the heterogeneity of CCA using single-cell sequencing technology, with the ultimate goal of identifying possible biomarkers and potential treatment targets.

FGFR2 testing in cholangiocarcinoma: translating molecular studies into clinical practice

Cholangiocarcinoma (CCA) is a heterogeneous group of neoplasms burdened by a dismal prognosis. Several studies have investigated the genomic profile of CCA and identified numerous druggable genetic alterations, including FGFR2 fusions/rearrangements. Approximately 5-7% of CCAs and 10-20% of intrahepatic iCCAs harbor FGFR2 fusions. With the recent advent of FGFR-targeting therapies into clinical practice, a standardization of molecular testing for FGFR2 alterations in CCA will be necessary. In this review, we describe the technical aspects and challenges related to FGFR2 testing in routine practice, focusing on the comparison between Next-Generation Sequencing (NGS) and FISH assays, the best timing to perform the test, and on the role of liquid biopsy.

Capturing the Dynamic Conformational Changes of Human Isocitrate Dehydrogenase 1 (IDH1) upon Ligand and Metal Binding Using Hydrogen-Deuterium Exchange Mass Spectrometry

Human isocitrate dehydrogenase 1 (IDH1) is a highly conserved metabolic enzyme that catalyzes the interconversion of isocitrate and α-ketoglutarate. Kinetic and structural studies with IDH1 have revealed evidence of striking conformational changes that occur upon binding of its substrates, isocitrate and NADP⁺, and its catalytic metal cation. Here, we used hydrogen-deuterium exchange mass spectrometry (HDX-MS) to build a comprehensive map of the dynamic conformational changes experienced by IDH1 upon ligand binding. IDH1 proved well-suited for HDX-MS analysis, allowing us to capture profound changes in solvent accessibility at substrate binding sites and at a known regulatory region, as well as at more distant local subdomains that appear to support closure of this protein into its active conformation. HDX-MS analysis suggested that IDH1 is primarily purified with NADP(H) bound in the absence of its metal cation. Subsequent metal cation binding, even in the absence of isocitrate, was critical for driving large conformational changes. WT IDH1 folded into its fully closed conformation only when the full complement of substrates and metal was present. Finally, we show evidence supporting a previously hypothesized partially open conformation that forms prior to the catalytically active state, and we propose this conformation is driven by isocitrate binding in the absence of metal.

Developments in FGFR and IDH inhibitors for cholangiocarcinoma therapy

INTRODUCTION

Cholangiocarcinoma (CCA) is an uncommon malignancy originating from epithelial cells of the biliary tract. Regardless of the site of origin within the biliary tree, CCAs are generally aggressive with a poor survival. Surgical resection remains the only chance for cure, yet a majority of patients are not surgical candidates at presentation. Unfortunately, systemic therapies are often ineffective and complicated by side effects. As such, more effective targeted therapies are required in order to improve survival.

AREA COVERED

Genetic analysis of CCA has allowed for a better understanding of the genomic landscape of CCA. Isocitrate dehydrogenase (IDH) and fibroblast growth factor receptor (FGFR) mutations have emerged as the most promising molecular targets for CCA. Inhibitors of IDH and FGFR have proven to have therapeutic benefit with an acceptable safety profile. However, patients often develop resistance rendering the therapy ineffective.

EXPERT OPINION

Understanding the molecular pathways of IDH and FGFR may lead to a better understanding of the mechanisms of resistance. Thus, novel therapies may be developed to improve the efficacy of these therapies. Developing novel biomarkers may improve patient selection and further enhance effectiveness of targeted therapies.

The regulatory mechanisms and inhibitors of isocitrate dehydrogenase 1 in cancer

Reprogramming of energy metabolism is one of the basic characteristics of cancer and has been proved to be an important cancer treatment strategy. Isocitrate dehydrogenases (IDHs) are a class of key proteins in energy metabolism, including IDH1, IDH2, and IDH3, which are involved in the oxidative decarboxylation of isocitrate to yield α-ketoglutarate (α-KG). Mutants of IDH1 or IDH2 can produce d-2-hydroxyglutarate (D-2HG) with α-KG as the substrate, and then mediate the occurrence and development of cancer. At present, no IDH3 mutation has been reported. The results of pan-cancer research showed that IDH1 has a higher mutation frequency and involves more cancer types than IDH2, implying IDH1 as a promising anti-cancer target. Therefore, in this review, we summarized the regulatory mechanisms of IDH1 on cancer from four aspects: metabolic reprogramming, epigenetics, immune microenvironment, and phenotypic changes, which will provide guidance for the understanding of IDH1 and exploring leading-edge targeted treatment strategies. In addition, we also reviewed available IDH1 inhibitors so far. The detailed clinical trial results and diverse structures of preclinical candidates illustrated here will provide a deep insight into the research for the treatment of IDH1-related cancers.

The multidisciplinary management of cholangiocarcinoma

Cholangiocarcinoma is a lethal malignancy of the biliary epithelium that can arise anywhere along the biliary tract. Surgical resection confers the greatest likelihood of long-term survivability. However, its insidious onset, difficult diagnostics, and resultant advanced presentation render the majority of patients unresectable, highlighting the importance of early detection with novel biomarkers. Developing liver-directed therapies and emerging targeted therapeutics may offer improved survivability for patients with unresectable or advanced disease. In this article, the authors review the current multidisciplinary standards of care in resectable and unresectable cholangiocarcinoma, with an emphasis on novel biomarkers for early detection and nonsurgical locoregional therapy options.

A phase II single arm study of Nivolumab with stereotactic Ablative radiation Therapy after induction chemotherapy in CHOlangiocarcinoma (NATCHO)

BACKGROUND

Intrahepatic cholangiocarcinoma (CCA) is amongst the most common primary liver tumors worldwide. CCA carries a bad prognosis prompting research to establish new treatment modalities other than surgery and the current chemotherapeutic regimens adopted. Hence, this trial explores a new therapeutic approach, to combine stereotactic body radiation therapy (SBRT) and immunotherapy (Nivolumab), and asses its clinical benefit and safety profile after induction chemotherapy in CCA.

METHODOLOGY

This is a Phase II open-label, single-arm, multicenter study that investigates Nivolumab (PD-1 inhibitor) treatment at Day 1 followed by SBRT (30 Gy in 3 to 5 fractions) at Day 8, then monthly Nivolumab in 40 patients with non-resectable locally advanced, metastatic or recurrent intrahepatic or extrahepatic CCA. Eligible patients were those above 18 years of age with a pathologically and radiologically confirmed diagnosis of non-resectable locally advanced or metastatic or recurrent intrahepatic or extrahepatic CCA, following 4 cycles of cisplatin-based chemotherapy with an estimated life expectancy of more than 3 months, among other criteria. The primary endpoint is the progression free survival (PFS) rate at 8 months and disease control rate (DCR). The secondary endpoints are overall survival (OS), tumor response rate (TRR), duration of response, evaluation of biomarkers: CD3 + , CD4 + and CD8 + T cell infiltration, as well as any change in the PD-L1 expression through percutaneous core biopsy when compared with the baseline biopsy following 1 cycle of Nivolumab and SBRT.

DISCUSSION

SRBT alone showed promising results in the literature by both inducing the immune system locally and having abscopal effects on distant metastases. Moreover, given the prevalence of PD-L1 in solid tumors, targeting it or its receptor has become the mainstay of novel immunotherapeutic drugs use. A combination of both has never been explored in the scope of CCA and that is the aim of this study.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04648319 , April 20, 2018.

Bcl-xL as prognostic marker and potential therapeutic target in cholangiocarcinoma

Intrahepatic, perihilar, and distal cholangiocarcinoma (iCCA, pCCA, dCCA) are highly malignant tumours with increasing mortality rates due to therapy resistances. Among the mechanisms mediating resistance, overexpression of anti-apoptotic Bcl-2 proteins (Bcl-2, Bcl-x_L , Mcl-1) is particularly important. In this study, we investigated whether antiapoptotic protein patterns are prognostically relevant and potential therapeutic targets in CCA. Bcl-2 proteins were analysed in a pan-cancer cohort from the NCT/DKFZ/DKTK MASTER registry trial (n = 1140, CCA n = 72) via RNA-sequencing and transcriptome-based protein activity interference revealing high ranks of CCA for Bcl-x_L and Mcl-1. Expression of Bcl-x_L , Mcl-1, and Bcl-2 was assessed in human CCA tissue and cell lines compared with cholangiocytes by immunohistochemistry, immunoblotting, and quantitative-RT-PCR. Immunohistochemistry confirmed the upregulation of Bcl-x_L and Mcl-1 in iCCA tissues. Cell death of CCA cell lines upon treatment with specific small molecule inhibitors of Bcl-x_L (Wehi-539), of Mcl-1 (S63845), and Bcl-2 (ABT-199), either alone, in combination with each other or together with chemotherapeutics was assessed by flow cytometry. Targeting Bcl-x_L induced cell death and augmented the effect of chemotherapy in CCA cells. Combined inhibition of Bcl-x_L and Mcl-1 led to a synergistic increase in cell death in CCA cell lines. Correlation between Bcl-2 protein expression and survival was analysed within three independent patient cohorts from cancer centers in Germany comprising 656 CCA cases indicating a prognostic value of Bcl-x_L in CCA depending on the CCA subtype. Collectively, these observations identify Bcl-x_L as a key protein in cell death resistance of CCA and may pave the way for clinical application.

Clinical Practice of Targeted Capture Sequencing to Identify Actionable Alterations in Cholangiocarcinoma

The early diagnosis and treatment of cholangiocarcinoma (CCA) remain a challenge worldwide. Genetic testing promises to solve these problems. Due to the different mutation landscapes across populations and the paucity of sequencing data of Chinese patients with CCA, the existing mutation landscape is insufficient to reflect the mutation characteristics of Chinese patients. Thus, we retrospectively analyzed 72 Chinese patients with CCA who had received genetic testing of targeted capture sequencing. A total of 2152 somatic mutations were detected in 56 (77.78%) patients, of which, the frequently mutated driver genes were TP53 (27.78%), KMT2D (23.81%), KMT2C (20.63%), BCOR (18.06%), APC (15.28%), BAP1 (13.89%), ARID1A (12.50%), NF1 (12.50%), PIK3CA (12.50%), KRAS (11.11%), and LRP1B (11.11%). Most mutations were enriched in NRF2, TP53, and TGF-Beta oncogenic signaling pathways and cadherin repeat domains which were associated with intercellular adhesion. Based on cancer-related public databases and multiple protein function prediction algorithms, we identified 118 novel pathogenic or likely pathogenic somatic mutations and 77 actionable alterations. Molecular analysis of tumors from a precision oncology perspective can provide potential targets for early diagnosis and treatment of CCA and assist physicians in clinical decision making.

Distinctive Metabolism-Associated Gene Clusters That Are Also Prognostic in Intrahepatic Cholangiocarcinoma and Hepatocellular Carcinoma

Objective

To offer new prognostic evaluations by exploring potentially distinctive genetic features of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC).

Methods

There were 12 samples for gene expression profiling processes in this study. These included three HCC lesion samples and their matched adjacent nontumor liver tissues obtained from patients with HCC, as well as three ICC samples and their controls collected similarly. In addition to the expression matrix generated on our own, profiles of other cohorts from The Cancer Genome Atlas (TCGA) program and the Gene Expression Omnibus (GEO) were also employed in later bioinformatical analyses. Differential analyses, functional analyses, protein interaction network analyses, and gene set variation analyses were used to identify key genes. To establish the prognostic models, univariate/multivariate Cox analyses and subsequent stepwise regression were applied, with the Akaike information criterion evaluating the goodness of fitness.

Results

The top three pathways enriched in HCC were all metabolism-related; they were fatty acid degradation, retinol metabolism, and arachidonic acid metabolism. In ICC, on the other hand, additional pathways related to fat digestion and absorption and cholesterol metabolism were identified. Consistent characteristics of such a metabolic landscape were observed across different cohorts. A prognostic risk score model for calculating HCC risk was constructed, consisting of ADH4, ADH6, CYP2C9, CYP4F2, and RDH16. This signature predicts the 3-year survival with an AUC area of 0.708 (95%CI = 0.644 to 0.772). For calculating the risk of ICC, a prognostic risk score model was built upon the expression levels of CYP26A1, NAT2, and UGT2B10. This signature predicts the 3-year survival with an AUC area of 0.806 (95% CI = 0.664 to 0.947).

Conclusion

HCC and ICC share commonly abrupted pathways associated with the metabolism of fatty acids, retinol, arachidonic acids, and drugs, indicating similarities in their pathogenesis as primary liver cancers. On the flip side, these two types of cancer possess distinctive promising biomarkers for predicting overall survival or potential targeted therapies.

Metabolic reprogramming in cholangiocarcinoma

Metabolic reprogramming is a hallmark of cancer and allows tumour cells to meet the increased energy demands required for rapid proliferation, invasion, and metastasis. Indeed, many tumour cells acquire distinctive metabolic and bioenergetic features that enable them to survive in resource-limited conditions, mainly by harnessing alternative nutrients. Several recent studies have explored the metabolic plasticity of cancer cells with the aim of identifying new druggable targets, while therapeutic strategies to limit the access to nutrients have been successfully applied to the treatment of some tumours. Cholangiocarcinoma (CCA), a highly heterogeneous tumour, is the second most common form of primary liver cancer. It is characterised by resistance to chemotherapy and poor prognosis, with 5-year survival rates of below 20%. Deregulation of metabolic pathways have been described during the onset and progression of CCA. Increased aerobic glycolysis and glutamine anaplerosis provide CCA cells with the ability to generate biosynthetic intermediates. Other metabolic alterations involving carbohydrates, amino acids and lipids have been shown to sustain cancer cell growth and dissemination. In this review, we discuss the complex metabolic rewiring that occurs during CCA development and leads to unique nutrient addiction. The possible role of therapeutic interventions based on metabolic changes is also thoroughly discussed.

Genomic architecture of FGFR2 fusions in cholangiocarcinoma and its implication for molecular testing

Background

Cholangiocarcinoma (CCA) is a primary malignancy of the biliary tract with a dismal prognosis. Recently, several actionable genetic aberrations were identified with significant enrichment in intrahepatic CCA, including FGFR2 gene fusions with a prevalence of 10–15%. Recent clinical data demonstrate that these fusions are druggable in a second-line setting in advanced/metastatic disease and the efficacy in earlier lines of therapy is being evaluated in ongoing clinical trials. This scenario warrants standardised molecular profiling of these tumours.

Methods

A detailed analysis of the original genetic data from the FIGHT-202 trial, on which the approval of Pemigatinib was based, was conducted.

Results

Comparing different detection approaches and displaying representative cases, we described the genetic landscape and architecture of FGFR2 fusions in iCCA and show biological and technical aspects to be considered for their detection. We elaborated parameters, including a suggestion for annotation, that should be stated in a molecular diagnostic FGFR2 report to allow a complete understanding of the analysis performed and the information provided.

Conclusion

This study provides a detailed presentation and dissection of the technical and biological aspects regarding FGFR2 fusion detection, which aims to support molecular pathologists, pathologists and clinicians in diagnostics, reporting of the results and decision-making.

Role of molecular genetics in the clinical management of cholangiocarcinoma

The incidence of cholangiocarcinoma (CCA) has steadily increased during the past 20 years, and mortality is increasing. The majority of patients with CCA have advanced or metastatic disease at diagnosis, and treatment options for unresectable disease are limited, resulting in poor prognosis. However, recent identification of targetable genomic alterations has expanded treatment options for eligible patients. Given the importance of early and accurate diagnosis in optimizing patient outcomes, this review discusses best practices in CCA diagnosis, with a focus on categorizing molecular genetics and available targeted therapies. Imaging and staging of CCAs are discussed, as well as recommended biopsy collection techniques, and molecular and genomic profiling methodologies, which have become increasingly important as molecular biomarker data accumulate. Approved agents targeting actionable genomic alterations specifically in patients with CCA include ivosidenib for tumors harboring IDH1 mutations, and infigratinib and pemigatinib for those with FGFR2 fusions. Other agents currently under development in this indication have shown promising results, which are presented here.

Up-to-Date Pathologic Classification and Molecular Characteristics of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) is an aggressive primary liver malignancy with an increasing incidence worldwide. Recently, histopathologic classification of small duct type and large duct type iCCA has been introduced. Both these types of tumors exhibit differences in clinicopathological features, mutational profiles, and prognosis. Small duct type iCCA is composed of non-mucin-producing cuboidal cells, whereas large duct type iCCA is composed of mucin-producing columnar cells, reflecting different cells of origin. Large duct type iCCA shows more invasive growth and poorer prognosis than small duct type iCCA. The background liver of small duct type iCCA often shows chronic liver disease related to hepatitis B or C viral infection, or alcoholic or non-alcoholic fatty liver disease/steatohepatitis, in contrast to large duct type iCCA that is often related to hepatolithiasis and liver fluke infection. Cholangiolocarcinoma is a variant of small duct type iCCA composed of naïve-looking cuboidal cells forming cords or ductule-like structures, and shows better prognosis than the conventional small duct type. Fibrous tumor stroma, one of the characteristic features of iCCA, contains activated fibroblasts intermixed with innate and adaptive immune cells. The types of stroma (mature versus immature) are related to tumor behavior and prognosis. Low tumor-infiltrating lymphocyte density, KRAS alteration, and chromosomal instability are related to immune-suppressive tumor microenvironments with resistance to programmed death 1/ programmed death ligand 1 blockade. Data from recent large-scale exome analyses have revealed the heterogeneity in the molecular profiles of iCCA, showing that small duct type iCCA exhibit frequent BAP1, IDH1/2 hotspot mutations and FGFR2 fusion, in contrast to frequent mutations in KRAS, TP53, and SMAD4 observed in large duct type iCCA. Multi-omics analyses have proposed several molecular classifications of iCCA, including inflammation class and proliferation class. The inflammation class is enriched in inflammatory signaling pathways and expression of cytokines, while the proliferation class has activated oncogenic growth signaling pathways. Diverse pathologic features of iCCA and its associated multi-omics characteristics are currently under active investigation, thereby providing insights into precision therapeutics for patients with iCCA. This review provides the latest knowledge on the histopathologic classification of iCCA and its associated molecular features, ranging from tumor microenvironment to genomic and transcriptomic research.

Gene Fusions in Gastrointestinal Tract cancers

Fusion genes have been identified a wide array of human neoplasms including hematologic and solid tumors, including gastrointestinal tract neoplasia. A fusion gene is the product of parts of two genes which are joined together following a deletion, translocation or chromosomal inversion. Together with single nucleotide variants, insertions, deletions, and amplification, fusion genes represent one of the key genomic mechanisms for tumor development. Detecting fusions in the clinic is accomplished by a variety of techniques including break-apart fluorescence in situ hybridization (FISH), reverse transcription-polymerase chain reaction (RT-PCR), and next-generation sequencing (NGS). Some recurrent gene fusions have been successfully targeted by small molecule or monoclonal antibody therapies (i.e. targeted therapies), while others are used for as biomarkers for diagnostic and prognostic purposes. The purpose of this review article is to discuss the clinical utility of detection of gene fusions in carcinomas and neoplasms arising primarily in the digestive system. This article is protected by copyright. All rights reserved.

Novel and emerging targets for cholangiocarcinoma progression: therapeutic implications

INTRODUCTION

Cholangiocarcinoma (CCA) is a heterogeneous group of aggressive biliary malignancies. While surgery and liver transplantation are the only potentially curative modalities for early-stage disease, limited options are available for most patients with incurable-stage disease. Survival outcomes remain dismal. Recent molecular profiling efforts have led to improved understanding of the genomic landscape of CCA and to the identification of subgroups with distinct diagnostic, prognostic, and therapeutic implications.

AREAS COVERED

: We provide an updated review and future perspectives on features of cholangiocarcinogenesis that can be translated into therapeutic biomarkers and targets. We highlight the critical studies that have established current systemic chemotherapy and targeted therapeutics, while elaborating on novel targeted and immunotherapeutic approaches in development. Relevant literature and clinical studies were identified by searching PubMed and www.ClinicalTrials.gov.

EXPERT OPINION

: While therapies targeting the various molecular subgroups of CCA are rapidly emerging and changing treatment paradigms, their success has been limited by the genetic heterogeneity of CCA and the plasticity of the targets. Novel strategies aiming to combine immunotherapy, chemotherapy, and molecularly-targeted therapeutics will be required to offer durable clinical benefit and maximize survival.

An Insight into Cholangiocarcinoma and Recent Advances in its Treatment

BACKGROUND

Cholangiocarcinoma (CCA) is a malignant disease of the epithelial cells of the intrahepatic and extrahepatic bile ducts. This review focuses on various aspects of cholangiocarcinoma such as its associated causes, treatment criteria, and more.

METHODS

Although it remains a rare malignancy and is the second most common primary malignancy of the liver, the incidence is increasing, especially the incidence of intrahepatic CCA. Several studies suggested that surgery is not only solution; recently, reported targeted drugs may have the potential to become an alternative option.

RESULTS

This review provides an overview of the current scenario of targeted therapies for CCA, which were tabulated with their current status and it also included its associated causes and its treatment criteria.

CONCLUSION

Because of its rarity and complexity, surgery remains the preferred treatment in resectable patients. Howerver, the studies suggested that the recently reported drugs may have the potential to be an alternative option for the treatment of CCA and related complications. In addition, this review will certainly benefit the community and researcher for further investigation.

Metabolic adaptations in cancers expressing isocitrate dehydrogenase mutations

The most frequently mutated metabolic genes in human cancer are those encoding the enzymes isocitrate dehydrogenase 1 (IDH1) and IDH2; these mutations have so far been identified in more than 20 tumor types. Since IDH mutations were first reported in glioma over a decade ago, extensive research has revealed their association with altered cellular processes. Mutations in IDH lead to a change in enzyme function, enabling efficient conversion of 2-oxoglutarate to R-2-hydroxyglutarate (R-2-HG). It is proposed that elevated cellular R-2-HG inhibits enzymes that regulate transcription and metabolism, subsequently affecting nuclear, cytoplasmic, and mitochondrial biochemistry. The significance of these biochemical changes for tumorigenesis and potential for therapeutic exploitation remains unclear. Here we comprehensively review reported direct and indirect metabolic changes linked to IDH mutations and discuss their clinical significance. We also review the metabolic effects of first-generation mutant IDH inhibitors and highlight the potential for combination treatment strategies and new metabolic targets.

R-2HG downregulates ERα to inhibit cholangiocarcinoma via the FTO/m6A-methylated ERα/miR16-5p/YAP1 signal pathway

Isocitrate dehydrogenase (IDH) mutations increase (R)-2-hydroxyglutarate (R-2HG) production; however, functional mechanisms of R-2HG in regulating cholangiocarcinoma (CCA) development remain to be further investigated. We first applied the CRISPR-Cas9 gene-editing system to create IDH1R132H-mutated CCA cells. Interestingly, our data showed that R-2HG could function through downregulating estrogen receptor alpha (ERα) and Yes-associated protein 1 (YAP1) pathways to decrease CCA growth. Detailed mechanistic studies revealed that R-2HG could target and degrade the fat mass and obesity-associated protein (FTO), the first identified mRNA demethylase. This reduced FTO can increase the N⁶-methyladenosine (m6A) to methylate the mRNA of ERα, and consequently decrease protein translation of the ERα. Further mechanistic studies revealed that ERα could transcriptionally suppress miR-16-5p expression, which could then increase YAP1 expression due to the reduced miR-16-5p binding to the 3′ UTR of YAP1. Furthermore, data from the pre-clinical animal model with implantation of IDH1R132H QBC939 cells demonstrated that R-2HG generated by the IDH1 mutation could downregulate ERα and YAP1 to suppress CCA tumor growth. Taken together, our new findings suggested that IDH1 mutation-induced R-2HG could suppress CCA growth via regulating the FTO/m6A-methylated ERα/miR16-5p/YAP1 signaling pathway. Upregulating R-2HG or downregulating the ERα signal by short hairpin RNA ERα (shERα) or antiestrogen could be effective strategies to inhibit CCA.

Isocitrate dehydrogenase gene variants in cancer and their clinical significance

Human isocitrate dehydrogenase (IDH) genes encode for the IDH1, 2 & 3 isoenzymes which catalyse the formation of 2-oxoglutarate from isocitrate and are essential for normal mammalian metabolism. Although mutations in these genes in cancer were long thought to lead to a 'loss of function', combined genomic and metabolomic studies led to the discovery that a common IDH 1 mutation, present in low-grade glioma and acute myeloid leukaemia (AML), yields a variant (R132H) with a striking change of function leading to the production of (2R)-hydroxyglutarate (2HG) which consequently accumulates in large quantities both within and outside cells. Elevated 2HG is proposed to promote tumorigenesis, although the precise mechanism by which it does this remains uncertain. Inhibitors of R132H IDH1, and other subsequently identified cancer-linked 2HG producing IDH variants, are approved for clinical use in the treatment of chemotherapy-resistant AML, though resistance enabled by additional substitutions has emerged. In this review, we provide a current overview of cancer linked IDH mutations focussing on their distribution in different cancer types, the effects of substitution mutations on enzyme activity, the mode of action of recently developed inhibitors, and their relationship with emerging resistance-mediating double mutations.

Image-Guided Local Treatment for Unresectable Intrahepatic Cholangiocarcinoma-Role of Interventional Radiology

Intrahepatic cholangiocarcinoma is a highly aggressive malignancy with an increasing incidence in recent years. Prognosis is poor and most patients are not eligible for resection at the time of initial diagnosis due to the anatomic location, inadequate hepatic reserve, limiting comorbidities or metastatic disease. Several locoregional therapies from the field of interventional radiology exist for patients who are not amenable for surgery, or in case of local recurrence as a single treatment modality or combined with systemic treatment. To date, evidence is limited, with most conclusions drawn from single-center studies with small patient cohorts, often treated in the salvage situation or for local recurrence after initial resection. Nevertheless, the results are promising and suggest a survival benefit in selected patients. This narrative review focuses on the use of different locoregional treatment options for intrahepatic cholangiocarcinoma.

Current State of Multidisciplinary Treatment in Cholangiocarcinoma

BACKGROUND

Cholangiocarcinoma (CCA) is a highly aggressive malignancy, and its incidence seems to be increasing over the last years. Given the high rate of irresectability at the time of initial diagnosis, new treatment approaches are important to achieve better patient outcomes. Our review provides an overview of current multimodal therapy options across different specialties of gastroenterology/oncology, surgery, and interventional radiology.

SUMMARY

CCA is subdivided into clinically and molecularly distinct phenotypes. Surgical treatment currently is the only potentially curative therapy, but unfortunately, the majority of all patients are not eligible for resection at the time of initial diagnosis due to anatomic location, inadequate hepatic reserve, metastatic disease, or limiting comorbidities. However, multimodal treatment options are available to prolong survival, relieve symptoms, and maintain life quality.

KEY MESSAGES

The treatment of CCA is complex and requires close interdisciplinary collaboration and individualized treatment planning to ensure optimal patient care at specialized centers. Molecular profiling of patients and inclusion into clinical trials is highly recommended.

IDH1 and IDH2 Mutations in Colorectal Cancers

OBJECTIVES

To elucidate clinicopathologic and molecular characteristics of IDH1 and IDH2 (IDH1/2) mutations in colorectal cancers (CRCs).

METHODS

We evaluated IDH1/2 mutations in 1,623 CRCs using a next-generation sequencing assay.

RESULTS

IDH1/2 mutations, predominantly IDH1 p.R132C, were detected in 15 (0.9%) CRCs and in 5 (3.0%) of 167 BRAF p.V600E-mutated CRCs. Three IDH1/2-mutated CRCs were associated with inflammatory bowel disease. They were significantly associated with old age, mucinous or signet ring cell adenocarcinoma, and high-grade histomorphology. Concordance of variant allele frequency between IDH1/2 mutants and other trunk drivers in CRCs and presence of IDH1/2 mutation in the adenoma and early adenocarcinoma indicated IDH1/2 mutations could be trunk drivers suitable for targeted therapy.

CONCLUSIONS

IDH1/2 mutations in CRCs were uncommon but enriched in BRAF p.V600E-mutated CRCs and perhaps colitis-associated CRCs. Further studies on IDH1/2-mutated CRCs are needed to clarify their clinicopathologic features and implications for targeted therapy.

Novel biomarkers for cholangiocarcinoma: how can it enhance diagnosis, prognostication, and investigational drugs? Part-1

INTRODUCTION

The development of novel biomarkers for cancer has exploded over the last decade with advances in novel technologies. Cholangiocarcinoma (CCA), a cancer of the bile ducts, has a dearth of strong disease and pathophysiology biomarkers, making early detection and prognostication a difficult task.

AREAS COVERED

In this comprehensive review, we discuss the spectrum of biomarkers for CCA diagnosis and prognostication. We elaborate on novel biomarker discovery through a comprehensive multi-omics approach. We also cover, how certain biomarkers may also serve as unique and potent targets for therapeutic development.

EXPERT OPINION

Despite the relatively poor diagnostic and prognostic performance of existing biomarkers for CCA, there is a vast range of novel biomarkers with exquisite diagnostic and prognostic performance for CCA in the pipeline. Moreover, these biomarkers may serve as potential targets for precision medicine. Existing strategies to target unique biomolecular classes are discussed, within the context of an overall 'omics' focused profiling strategy. Omics profiling will simultaneously allow for enhanced biomarker development and identification of unique subtypes of cholangiocarcinoma and how they are influenced by an individual's unique context. In this manner, patient management strategy and clinical trial design can be optimized to the individual.

Advances in the management of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a primary malignancy of the bile ducts with three anatomically and molecularly distinct entities: Intrahepatic CCA (iCCA), perihilar CCA (pCCA), and distal CCA. As a result of phenotypic and anatomic differences they differ significantly with respect to management. For each type of CCA there have been significant changes in management over the last several years which will be discussed in this review. Although resection remains the standard of care for all types of CCA, liver transplantation has been established as curative treatment for selected patients with pCCA and is being evaluated for iCCA with early success. With respect to systemic therapy capecitabine is now first line adjuvant therapy for all biliary tract malignancies after curative intent resection. Progress in exploiting the pathologic mutations and molecular abnormalities has also yielded regulatory approval of targeted therapy for CCA in patients with acquired alterations in the fibroblast growth factor receptor. There is also increased consensus in managing malignant biliary obstruction associated with CCA where pre-operative biliary stenting is not beneficial while self-expanding metal stents have been shown to be superior to plastic stents in patients who are not surgical candidates.

Molecular-driven treatment for biliary tract cancer: the promising turning point

INTRODUCTION

In the past, targeted therapies have not shown positive results as they have been used without adequate molecular selection of patients with biliary tract cancer (BTC). This has led to an expansion of research on characteristics and molecular selection to identify new effective strategies in this setting. Improved knowledge of the molecular biology of these neoplasms has highlighted their extraordinary heterogeneity and has made it possible to identify targetable gene alterations, including fibroblast growth factor receptor (FGFR) 2 gene fusions, and isocitrate dehydrogenase (IDH) mutations. The FDA recently approved ivosidenib and pemigatinib for the treatment of BTCs.

AREAS COVERED

We review data in the literature regarding targeted therapies for the treatment of BTCs, as well as on the prospects deriving from the extraordinary molecular heterogeneity of these neoplasms.

EXPERT OPINION

At present, it is essential to evaluate the expression of the genetic alterations expressed by these neoplasms to offer patients an increasingly personalized therapeutic approach. Studies are needed to better define the limits and potentials of targeted therapies and their role in the therapeutic algorithm to improve the poor prognosis of these patients.

Cholangiocarcinoma Therapeutics: An Update

BACKGROUND

Cholangiocarcinoma (CCA) is the second most common hepatobiliary cancer and associated with a poor prognosis. Only one-third of CCA cases are diagnosed at operable stages. However, a high rate of relapse has been observed postoperatively. Besides screening for operable individuals, efficacious therapeutic for recurrent and advanced CCA is urgently needed. The treatment outcome of available therapeutics is important to clarify clinical indication and facilitate the development of treatment strategies.

OBJECTIVE

This review aims to compare the treatment outcome of different therapeutics based on both overall survival and progression-free survival.

METHODS

Over one hundred peer-reviewed articles were examined. We compared the treatment outcome between different treatment methods, including tumor resection with or without postoperative systematic therapy, chemotherapies including FOFLOX, and targeted therapies, such as IDH1, K-RAS, and FGFR inhibitors. Notably, the scientific basis and outcome of available treatment methods were compared with the standard first-line therapy.

RESULTS

CCAs at early stages should firstly undergo tumor resection surgery, followed by postoperative treatment with Capecitabine. Chemotherapy can be considered as a preoperative option for unresectable CCAs. Inoperable CCAs with genetic aberrances like FGFR alterations, IDH1, and KRAS mutations should be considered with targeted therapies. Fluoropyrimidine prodrug (S-1)/Gemcitabine/Cisplatin and nab-Paclitaxel/Gemcitabine/Cisplatin show favorable outcome which hints at the triplet regimen to be superior to Gemcitabine/Cisplatin on CCA. The triplet chemotherapeutic should be tested further compared to Gemcitabine/Cisplatin among CCAs without genetic alterations. Gemcitabine plus S-1 was recently suggested as the convenient and equivalent standard first-line for advanced/recurrent biliary tract cancer.

CONCLUSION

This review provides a comparative outcome between novel targeted therapies and currently available therapeutics.

Genetic Determinants of Outcome in Intrahepatic Cholangiocarcinoma

BACKGROUND AND AIM

Genetic alterations in intrahepatic cholangiocarcinoma (iCCA) are increasingly well characterized, but their impact on outcome and prognosis remains unknown.

APPROACH AND RESULTS

This bi-institutional study of patients with confirmed iCCA (n = 412) used targeted next-generation sequencing of primary tumors to define associations among genetic alterations, clinicopathological variables, and outcome. The most common oncogenic alterations were isocitrate dehydrogenase 1 (IDH1; 20%), AT-rich interactive domain-containing protein 1A (20%), tumor protein P53 (TP53; 17%), cyclin-dependent kinase inhibitor 2A (CDKN2A; 15%), breast cancer 1-associated protein 1 (15%), FGFR2 (15%), polybromo 1 (12%), and KRAS (10%). IDH1/2 mutations (mut) were mutually exclusive with FGFR2 fusions, but neither was associated with outcome. For all patients, TP53 (P < 0.0001), KRAS (P = 0.0001), and CDKN2A (P < 0.0001) alterations predicted worse overall survival (OS). These high-risk alterations were enriched in advanced disease but adversely impacted survival across all stages, even when controlling for known correlates of outcome (multifocal disease, lymph node involvement, bile duct type, periductal infiltration). In resected patients (n = 209), TP53mut (HR, 1.82; 95% CI, 1.08-3.06; P = 0.03) and CDKN2A deletions (del; HR, 3.40; 95% CI, 1.95-5.94; P < 0.001) independently predicted shorter OS, as did high-risk clinical variables (multifocal liver disease [P < 0.001]; regional lymph node metastases [P < 0.001]), whereas KRASmut (HR, 1.69; 95% CI, 0.97-2.93; P = 0.06) trended toward statistical significance. The presence of both or neither high-risk clinical or genetic factors represented outcome extremes (median OS, 18.3 vs. 74.2 months; P < 0.001), with high-risk genetic alterations alone (median OS, 38.6 months; 95% CI, 28.8-73.5) or high-risk clinical variables alone (median OS, 37.0 months; 95% CI, 27.6-not available) associated with intermediate outcome. TP53mut, KRASmut, and CDKN2Adel similarly predicted worse outcome in patients with unresectable iCCA. CDKN2Adel tumors with high-risk clinical features were notable for limited survival and no benefit of resection over chemotherapy.

CONCLUSIONS

TP53, KRAS, and CDKN2A alterations were independent prognostic factors in iCCA when controlling for clinical and pathologic variables, disease stage, and treatment. Because genetic profiling can be integrated into pretreatment therapeutic decision-making, combining clinical variables with targeted tumor sequencing may identify patient subgroups with poor outcome irrespective of treatment strategy.

Druggable molecular alterations in bile duct cancer: potential and current therapeutic applications in clinical trials

Introduction: Cholangiocarcinomas (CCA) are rare tumors that are associated with a variety of molecular alterations. Many of these alterations are now actionable using drugs currently in development, and CCA may be a perfect example of application of a precision oncology approach. However, development of drugs in CCA faces the challenge of targeting rare alterations in a rare disease.Areas covered: In this review, we present the current data on targeted therapies in development for CCA, focusing on IDH1, FGFR2, BRAF, and HER2 alterations. We also discuss rationale for targeting other alterations, currently without specific development in CCA. We searched PubMed and google scholar in February 2021 for relevant articles and presentation in recent congress regarding the literature on molecular alterations, drugs in cholangiocarcinomas and biliary tract cancers.Expert opinion: Despite a strong rationale and promising early results, applying a precision oncology approach in CCA for everyday patients is still exposed to significant challenges: obtaining the molecular portrait of these tumors due to difficulties with biopsy access, complexities of drug development in subgroups of these relatively rare tumors, and sub-optimal access to drugs outside clinical trials.

Biomarkers in Hepatobiliary Cancers: What is Useful in Clinical Practice?

Hepatocellular carcinoma (HCC) and biliary tract cancers (BTC) exhibit a poor prognosis with 5-year overall survival rates around 15%, all stages combined. Most of these primary liver malignancies are metastatic at diagnostic, with only limited therapeutic options, relying mainly on systemic therapies. Treatment modalities are different yet partially overlapping between HCC and BTC. The complex molecular profile of BTC yields to several actionable therapeutic targets, contrary to HCC that remains the field of antiangiogenic drugs in non-molecularly selected patients. Immunotherapy is now validated in the first line in HCC in combination with bevacizumab, while clinical activity of single agent immunotherapy appears limited to a subset of patients in BTC, still poorly characterized, and combinations are currently under investigation. In this review, we provide a critical evaluation and grading of clinical relevance on (i) the main prognostic biomarkers in HCC and BTC, (ii) the main theragnostic biomarkers in both tumors, and lastly (iii) what is recommended in clinical practice.

Thyroid-Like Cholangiocarcinoma: Histopathological, Immunohistochemical, In-Situ Hybridization and Molecular Studies on an Uncommon Emerging Entity

Thyroid-like cholangiocarcinoma is a very uncommon variant of peripheral-type cholangiocarcinoma. To date, only 4 prior cases have been reported. The molecular features of this tumor have not been described. We report a case of a 60-year-old woman with a tumor that evolved over a period of 10 years. A left hepatectomy specimen showed an 11 cm tumor that on histology exhibited areas reminiscent of a thyroid tumor with follicular and insular features which were positive on immunohistochemistry for cytokeratin 7 and in-situ hybridization for albumin. A detailed molecular analysis failed to show mutations common to cholangiocarcinomas but revealed frameshift mutations in 2 chromatin-remodeling genes, CREBBP and KMNT2A. This case confirms that thyroid-like cholangiocarcinoma is a histologic variant of this tumor that is associated with relatively low growth. As most cholangiocarcinomas, it is diffusely positive for cytokeratin 7 and albumin by in-situ hybridization. Given its rarity, the molecular alterations in this specific histologic subtype remain to be fully elucidated.

Immunotherapy in Advanced Biliary Tract Cancers

Biliary tract cancers are rare tumors with a poor prognosis. Two-thirds of these primary liver malignancies are diagnosed at advanced stages where therapeutic options are limited. Whereas several molecular targeted therapies emerge in biliary tract cancers, immunotherapy is still investigational, the only approved immunotherapy to date being the immune checkpoint inhibitor pembrolizumab for the small fraction of patients with microsatellite-instable tumors. In microsatellite-stable, pre-treated biliary tract cancers, single-agent immune checkpoint blockade has a limited albeit often long-lasting clinical activity in a still ill-defined subgroup of patients. The identification of predictive biomarkers will allow a better selection of patients that may benefit from immunotherapy. Combinations of immunotherapies with each other, with chemotherapy or targeted molecular therapies are being investigated in early lines of therapy, including first-line.