Cholangiolar pattern and albumin in situ hybridisation enable a diagnosis of intrahepatic cholangiocarcinoma

Combined analysis of albumin in situ hybridisation and C reactive protein immunohistochemistry for the diagnosis of intrahepatic cholangiocarcinoma: towards a molecular classification paradigm

AIMS

Intrahepatic cholangiocarcinoma (iCCA) is a diagnosis of exclusion that can pose a challenge to the pathologist despite thorough clinical workup. Although several immunohistochemical markers have been proposed for iCCA, none of them reached clinical practice. We here assessed the combined usage of two promising diagnostic approaches, albumin in situ hybridisation (Alb-ISH) and C reactive protein (CRP) immunohistochemistry, for distinguishing iCCA from other adenocarcinoma primaries.

METHODS

We conducted Alb-ISH and CRP immunohistochemistry in a large European iCCA cohort (n=153) and compared the results with a spectrum of other glandular adenocarcinomas of different origin (n=885). In addition, we correlated expression patterns with clinicopathological information and mutation data.

RESULTS

Alb-ISH was highly specific for iCCA (specificity 98.8%) with almost complete negativity in perihilar CCA and only rare positives among other adenocarcinomas (sensitivity 69.5%). CRP identified the vast majority of iCCA cases (sensitivity 84.1%) at a lower specificity of 86.4%. Strikingly, the combination of CRP and Alb-ISH boosted the diagnostic sensitivity to 88.0% while retaining a considerable specificity of 86.1%. Alb-ISH significantly correlated with CRP expression, specific tumour morphologies and small or large duct iCCA subtypes. Neither Alb-ISH nor CRP was associated with iCCA patient survival. 16 of 17 recurrent mutations in either IDH1, IDH2 and FGFR2 affected Alb-ISH positive cases, while the only KRAS mutation corresponded to an Alb-ISH negative case.

CONCLUSIONS

In conclusion, we propose a sequential diagnostic approach for iCCA, integrating CRP immunohistochemistry and Alb-ISH. This may improve the accuracy of CCA classification and pave the way towards a molecular-guided CCA classification.

Morphologic and immunohistochemical characterization of small and large duct cholangiocarcinomas in a Western cohort: A panel of pCEA, CRP, N-cadherin, and albumin in situ hybridization aids in subclassification

Two morphologic subtypes of intrahepatic cholangiocarcinoma (iCCA), small duct and large duct, are now recognized, and importantly, these subtypes are associated with distinct molecular pathways and therapeutic options. Initial studies demonstrated the feasibility of morphologic subclassification and helped characterize the immunoprofile of the subtypes. However, few studies have been undertaken in Western countries where incidence of the subtypes is likely distinct from that in the East. To address this, 48 tumors from a North American cohort, consisting of 29 iCCAs, 18 extrahepatic CCAs (eCCAs), and 1 tumor of unclear origin (liver vs. gallbladder growing into liver) were classified by morphologic criteria as large duct (19 tumors), small duct (13 tumors), or indeterminate (13 tumors; all iCCAs). Notably, only 3 iCCAs were classified as large duct. Additionally, we evaluated the utility of common biomarkers to aid in subclassification, given that a significant portion of iCCAs were challenging to classify (e.g., indeterminate morphology). Tumors were screened for expression of mucicarmine, epithelial membrane antigen (EMA), monoclonal (mCEA), polyclonal CEA (pCEA), N-cadherin, CD56, and albumin by in situ hybridization (ALB-ISH). Of these, pCEA, CRP, N-cadherin, and ALB-ISH showed statistically significant differences between large and small duct types (P < 0.0028), with high specificity (≥88 %) and at least moderate sensitivity (≥60 %). Eleven of the 13 morphologically indeterminate tumors could be classified based on their expression of these 4 markers. Four additional large duct iCCAs were subsequently obtained from a second North American institution and assessed for pCEA, N-cadherin, and albumin expression. Combining these data with the initial cohort of large duct iCCAs (total of 7 large duct iCCAs) showed similar biomarker associations. In conclusion, in this Western cohort, 55 % of iCCAs (16 of 29) could be subclassified as large or small duct type based on morphology alone. With the aid of the 4-marker panel, 93 % of iCCAs (27 of 29) could be classified. Unlike in East Asian cohorts, the vast majority of iCCAs (88 %) was small duct type, and hepatolithiasis was not observed. CRP, N-cadherin, and ALB-ISH were found to be specific for small duct iCCA, whereas diffuse, strong expression of pCEA showed specificity for large duct tumors. This is the first report to highlight the utility of pCEA to subclassify iCCAs. Additionally, in cases in which the primary site (within the biliary tract) was unclear, CRP, ALB-ISH, N-cadherin, and pCEA were helpful in distinguishing iCCA from eCCA.

Challenges in Diagnosing and Reporting Cholangiocarcinoma

Intrahepatic cholangiocarcinoma is a challenge to the practicing surgical pathologist for several reasons. It is rare in many parts of the world, and thus practical exposure may be limited. Related to the fact of its rarity is the fact that more common tumors which frequently metastasize to the liver can be morphologically indistinguishable (eg, pancreatic ductal adenocarcinoma). Immunohistochemical testing is generally non-contributory in this context. Other difficulties arise from the protean morphologic manifestations of cholangiocarcinoma (ie, small duct vs. large duct) and the existence of combined cholangiocarcinoma and hepatocellular carcinoma. These, and other issues of concern to the practicing diagnostic pathologist are discussed herein.

SULT1A1-dependent sulfonation of alkylators is a lineage-dependent vulnerability of liver cancers

Adult liver malignancies, including intrahepatic cholangiocarcinoma and hepatocellular carcinoma, are the second leading cause of cancer-related deaths worldwide. Most individuals are treated with either combination chemotherapy or immunotherapy, respectively, without specific biomarkers for selection. Here using high-throughput screens, proteomics and in vitro resistance models, we identify the small molecule YC-1 as selectively active against a defined subset of cell lines derived from both liver cancer types. We demonstrate that selectivity is determined by expression of the liver-resident cytosolic sulfotransferase enzyme SULT1A1, which sulfonates YC-1. Sulfonation stimulates covalent binding of YC-1 to lysine residues in protein targets, enriching for RNA-binding factors. Computational analysis defined a wider group of structurally related SULT1A1-activated small molecules with distinct target profiles, which together constitute an untapped small-molecule class. These studies provide a foundation for preclinical development of these agents and point to the broader potential of exploiting SULT1A1 activity for selective targeting strategies.

An Expert, Multidisciplinary Perspective on Best Practices in Biomarker Testing in Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) is a rare and aggressive malignancy that arises from the intrahepatic biliary tree and is associated with a poor prognosis. Until recently, the treatment landscape of advanced/metastatic iCCA has been limited primarily to chemotherapy. In recent years, the advent of biomarker testing has identified actionable genetic alterations in 40%-50% of patients with iCCA, heralding an era of precision medicine for these patients. Biomarker testing using next-generation sequencing (NGS) has since become increasingly relevant in iCCA; however, several challenges and gaps in standard image-guided liver biopsy and processing have been identified. These include variability in tissue acquisition relating to the imaging modality used for biopsy guidance, the biopsy method used, number of passes, needle choice, specimen preparation methods, the desmoplastic nature of the tumor, as well as the lack of communication among the multidisciplinary team. Recognizing these challenges and the lack of evidence-based guidelines for biomarker testing in iCCA, a multidisciplinary team of experts including interventional oncologists, a gastroenterologist, medical oncologists, and pathologists suggest best practices for optimizing tissue collection and biomarker testing in iCCA.

N-Cadherin Distinguishes Intrahepatic Cholangiocarcinoma from Liver Metastases of Ductal Adenocarcinoma of the Pancreas

Carcinomas of the pancreatobiliary system confer an especially unfavorable prognosis. The differential diagnosis of intrahepatic cholangiocarcinoma (iCCA) and its subtypes versus liver metastasis of ductal adenocarcinoma of the pancreas (PDAC) is clinically important to allow the best possible therapy. We could previously show that E-cadherin and N-cadherin, transmembrane glycoproteins of adherens junctions, are characteristic features of hepatocytes and cholangiocytes. We therefore analyzed E-cadherin and N-cadherin in the embryonally related epithelia of the bile duct and pancreas, as well as in 312 iCCAs, 513 carcinomas of the extrahepatic bile ducts, 228 gallbladder carcinomas, 131 PDACs, and precursor lesions, with immunohistochemistry combined with image analysis, fluorescence microscopy, and immunoblots. In the physiological liver, N-cadherin colocalizes with E-cadherin in small intrahepatic bile ducts, whereas larger bile ducts and pancreatic ducts are positive for E-cadherin but contain decreasing amounts of N-cadherin. N-cadherin was highly expressed in most iCCAs, whereas in PDACs, N-cadherin was negative or only faintly expressed. E- and N-cadherin expression in tumors of the pancreaticobiliary tract recapitulate their expression in their normal tissue counterparts. N-cadherin is a helpful marker for the differential diagnosis between iCCA and PDAC, with a specificity of 96% and a sensitivity of 67% for small duct iCCAs and 50% for large duct iCCAs.

Optimizing the Diagnosis and Biomarker Testing for Patients with Intrahepatic Cholangiocarcinoma: A Multidisciplinary Approach

Cholangiocarcinoma (CCA) is a heterogenous group of malignancies originating in the biliary tree, and associated with poor prognosis. Until recently, treatment options have been limited to surgical resection, liver-directed therapies, and chemotherapy. Identification of actionable genomic alterations with biomarker testing has revolutionized the treatment paradigm for these patients. However, several challenges exist to the seamless adoption of precision medicine in patients with CCA, relating to a lack of awareness of the importance of biomarker testing, hurdles in tissue acquisition, and ineffective collaboration among the multidisciplinary team (MDT). To identify gaps in standard practices and define best practices, multidisciplinary hepatobiliary teams from the University of California (UC) Davis and UC Irvine were convened; discussions of the meeting, including optimal approaches to tissue acquisition for diagnosis and biomarker testing, communication among academic and community healthcare teams, and physician education regarding biomarker testing, are summarized in this review.

Primary hepatic neoplasms arising in cirrhotic livers can have a variable spectrum of neuroendocrine differentiation

Primary hepatic neoplasms with neuroendocrine differentiation are extremely rare. Their clinicopathological features and molecular genetic basis are largely unknown. We identified four cases of primary hepatic neoplasms with neuroendocrine differentiation. Electronic medical records were reviewed for clinical history, imaging findings, laboratory results, and follow-up. Pathology slides, immunohistochemistry, and ancillary studies were reviewed. There were two females and two males with age ranging from 52 to 74 years. There was one amphicrine carcinoma with tumor cells simultaneously demonstrating both hepatocellular and neuroendocrine differentiation, one mixed hepatocellular-neuroendocrine carcinoma (NEC) with hepatocellular component intermingled with neuroendocrine component, one small cell NEC, and one well-differentiated neuroendocrine tumor. Next- generation sequencing of the mixed hepatocellular-NEC and small cell NEC showed molecular/genetic alterations commonly seen in hepatocellular carcinoma (HCC). All four cases arose in a background of cirrhosis. Primary hepatic neoplasms arising in cirrhotic livers can have a spectrum of neuroendocrine differentiation. Presence of a NEC component may be an indicator of aggressiveness. In addition, primary hepatic carcinomas with neuroendocrine differentiation likely share the same molecular pathways as HCC.

Molecular and morphological changes induced by ivosidenib correlate with efficacy in mutant-IDH1 cholangiocarcinoma

Background: IDH1 mutations occur in approximately 13% of intrahepatic cholangiocarcinomas (IHCCs). The oral, targeted, mutant IDH1 (mIDH1) inhibitor ivosidenib (AG-120) suppresses production of the oncometabolite D-2-hydroxyglutarate, promoting disease stabilization and improved progression-free survival (PFS) in mIDH1 IHCC. Materials & methods: Harnessing matched baseline and on-treatment biopsies, we investigate the potential mechanisms underlying ivosidenib's efficacy. Results: mIDH1 inhibition leads to decreased cytoplasm and expression of hepatocyte lineage markers in patients with prolonged PFS. These findings are accompanied by downregulation of biliary fate, cell cycle progression and AKT pathway activity. Conclusion: Ivosidenib stimulates a hepatocyte differentiation program in mIDH1 IHCC, a phenotype associated with clinical benefit. mIDH1 inhibition could be a paradigm for differentiation-based therapy in solid tumors. Clinical trial registration: NCT02073994 (ClinicalTrials.gov).

A Subset of Intrahepatic Cholangiocarcinomas Express Albumin RNA as Detected by In Situ Hybridization

Intrahepatic cholangiocarcinomas (ICCs) show morphologic diversity, ranging from tumors composed of nonmucinous small ducts to mucin-producing large duct tumors to tumors with mixed hepatocellular carcinoma features. Diagnosing ICCs can be difficult, especially on biopsy, not only because of the morphologic diversity, but also because metastatic tumors are often in the differential diagnosis. Recently, branched DNA-based albumin RNA in situ hybridization (ISH) has been shown to be a potential sensitive and specific marker for ICC with 99% sensitivity. Using a different RNA ISH technology, we evaluated the expression of albumin RNA ISH in ICC. We performed RNA ISH for albumin using RNAscope on 43 ICCs in a triplicate tissue microarray. Albumin RNA ISH was positive in 18 of 43 (42%) ICCs. Five of the 6 (83%) combined hepatocellular carcinoma-CC were positive in the CC component. None of the tumors with mucin production were positive (0/9). In our cohort, albumin RNA ISH showed a sensitivity of 42% in ICCs, supporting the morphologic diversity of ICCs. Albumin RNA ISH does not appear to be a highly sensitive marker for ICC and hence cannot be used as a stand-alone marker for ICC.

Quantitative proteomic analysis of bile in extrahepatic cholangiocarcinoma patients

Background and Aims: Extrahepatic cholangiocarcinoma (CCA) without liver-fluke is increasing. Multifactorial carcinogenesis makes it hard to find biomarkers related to CCA. Although there are a few studies of bile proteomics, these showed different protein profiles because of having heterogeneous groups of patients and different sampling methods. Our aim was to identify the specific bile proteins of extrahepatic CCA patients. Methods: We collected bile from 23 patients undergoing endoscopic nasobiliary drainage in Korea University Guro Hospital from May 2018 to January 2019. The CCA group included 18 patients diagnosed with extrahepatic CCA, and the control group included 5 patients with benign biliary conditions. We analyzed bile proteome using liquid chromatography mass spectrometry. We compared the relative abundance of various proteins in the CCA and control groups. Results: In all, we identified a total of 245 proteins in the bile of CCA and control patients. Increased top 14 proteins in CCA patients were immunoglobulin kappa light chain, apolipoprotein B, inter-alpha-trypsin inhibitor heavy chain H4, apolipoprotein E, Mucin 5B, inter-alpha-trypsin inhibitor heavy chain H1, apolipoprotein A-IV, intercellular adhesion molecule 1, complement C7, complement C5, apolipoprotein C-III, albumin, antithrombin-III, and apolipoprotein A-II. However, the significantly increased proteins in bile of CCA patients comparing with control patients were immunoglobulin kappa light chain, apolipoprotein E, albumin, apolipoprotein A-I, antithrombin-III, α1-antitrypsin, serotransferrin, immunoglobulin heavy constant mu, immunoglobulin J chain, complement C4-A, and complement C3 (p<0.05). Conclusions: In this study, we identified several proteins that were significantly increased in the bile of extrahepatic CCA. Further study is needed to validate them as potential tumor-associated proteins that may be potential biomarkers for CCA.