Elia Gigante

Valérie Paradis

Maxime Ronot

François Cauchy

Olivier Soubrane

Nathalie Ganne-Carrié

MD Jean-Charles Nault
email: naultjc@gmail.com

New insights in physiopathology and clinical care of rare primary liver cancers

Keywords: mixed tumor, hepatocholangiocarcinoma, fibrolamellar carcinoma, hepatic hemangioendothelioma, hepatocellular carcinoma, hepatic angiosarcoma

survival (OS) Fluorescence in situ hybridization (FISH) Reverse transcription Polymerase chain reaction (Rt-PCR) Whole exome sequencing (WES) Whole genome sequencing (WGS) Immunohistochemistry (IHC) Epithelio-mesenchymal transition (EMT) Erythroblast transformation

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) account, respectively, for 85% and 10% of all primary hepatic cancers (PLC). Large cohort studies and randomized controlled trials are available and have allowed to propose international guidelines for the management of HCC and CCA. In contrast, rare PLC such as combined hepato-cholangiocarcinoma (cHCC-CCA), fibrolamellar carcinoma (FLC), hepatic hemangioendothelioma (HEE) and hepatic angiosarcoma (HAS) lack of prospective studies and clinical trials due to their scarcity. Herein, we want to summarize the recent advances in physiopathology and management of rare PLC.

Combined tumors hepato-cholangiocarcinoma

A matter of definition cHCC-CCA is characterized at histology by the presence of two distinct morphological patterns in the same lesion: HCC and intrahepatic CCA (iCCA)(1)(2). Several classifications have been proposed (supplementary Table 1) and were used sequentially in the literature leading to confusion. The discussion about terminology, based on recent morphological and molecular advances, excluded several types of PLC from cHCC-CCA: collision tumors, hepatoblastoma, typical HCCs with immunohistochemical expression of progenitor markers; typical iCCAs with immunohistochemical expression of hepatocytic markers. Whether intermediate cell carcinoma (INT) and cholangiolocellular carcinoma (CLC) should be classified within cHCC-CCA was debated.

A recent proposal of a consensus terminology [START_REF] Nagtegaal | The 2019 WHO classification of tumours of the digestive system[END_REF] divided PLC that cannot be included into either HCC or iCCA in three classes: 1. Tumors with the presence of hepatocytic and cholangiocytic histology mixed with a transition or separated areas within the same tumor, considered as combined HCC-CCA (cHCC-CCA). 2. PLC completely composed of "intermediate cells" (intermediate cell carcinoma), small cells of size intermediate between stem cells and hepatocytes with transitional morphology between hepatocytes and cholangiocytes, if this entity should be considered as a subtype of cHCC-CCA is still a matter of discussion [START_REF] Brunt | cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation[END_REF][START_REF] Sempoux | Combined hepatocellularcholangiocarcinoma and undifferentiated primary liver carcinoma[END_REF]. [START_REF] Nagtegaal | The 2019 WHO classification of tumours of the digestive system[END_REF]. PLC composed of pure CLC, if the main component of PLC is composed > 80% of cholangiolocarcinoma, finally reclassified in small duct iCCA [START_REF] Sempoux | Combined hepatocellularcholangiocarcinoma and undifferentiated primary liver carcinoma[END_REF].

According to this classification, the concept of "stem cell" phenotypes based on immunohistochemistry (EpCAM, CK19 and CD56) is not considered as a sub-category per-se, but rather as a feature that can be present in different types of PLC [START_REF] Brunt | cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation[END_REF]. Moreover, all subtypes of PLC could be associated in the same lesion with minor histological components observed in more than a half of cHCC-CCA [START_REF] Sasaki | Clinicopathological significance of 'subtypes with stem-cell feature' in combined hepatocellularcholangiocarcinoma[END_REF][START_REF] Akiba | Clinicopathologic analysis of combined hepatocellular-cholangiocarcinoma according to the latest WHO classification[END_REF]. If different subtypes are present, a precise description is recommended and the percentage of each tumor type present should be assessed in surgical specimens [START_REF] Brunt | cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation[END_REF].

Epidemiology and risk factors

Data from large databases reported a proportion of cHCC-CCA nearly 0.75% among all PLC with an incidence of 0.05/100 000 in the general population [START_REF] Garancini | Combined hepatocellular-cholangiocarcinoma: a population-level analysis of an uncommon primary liver tumor[END_REF][START_REF] Ramai | Combined Hepatocellular Cholangiocarcinoma: A Population-Based Retrospective Study[END_REF][START_REF] Kudo | Report of the 20th Nationwide follow-up survey of primary liver cancer in Japan[END_REF]. The incidence in monocentric studies based on resection or necropsies varies from 2.4% to 5.3% of PLC and the 2018 World Health Organization (WHO) classification estimates the frequency at 2%-5% [START_REF] Allen | Combined Liver Cell ahd Bile Duct Carcinoma[END_REF][START_REF] Brunt | cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation[END_REF][START_REF] Sempoux | Combined hepatocellularcholangiocarcinoma and undifferentiated primary liver carcinoma[END_REF][START_REF] Goodman | Combined hepatocellularcholangiocarcinoma. A histologic and immunohistochemical study[END_REF][START_REF] Ng | Combined hepatocellular-cholangiocarcinoma: a clinicopathological study[END_REF][START_REF] Jarnagin | Combined hepatocellular and cholangiocarcinoma: demographic, clinical, and prognostic factors[END_REF][START_REF] Lee | Comparison of combined hepatocellular and cholangiocarcinoma with hepatocellular carcinoma and intrahepatic cholangiocarcinoma[END_REF][START_REF] Edmondson | Primary carcinoma of the liver: a study of 100 cases among 48,900 necropsies[END_REF].

Risk factors associated with cHCC-CCA are shared with others PLC and include hepatitis B (HBV), hepatitis C (HCV), alcohol consumption, cirrhosis and male predominance (up to 79%) (Table 1). Association with cirrhosis is reported in several surgical series in eastern countries (26 to 81%); mostly associated with HBV infection [START_REF] Brunt | cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation[END_REF][START_REF] Ng | Combined hepatocellular-cholangiocarcinoma: a clinicopathological study[END_REF][START_REF] Lee | Comparison of combined hepatocellular and cholangiocarcinoma with hepatocellular carcinoma and intrahepatic cholangiocarcinoma[END_REF][START_REF] Taguchi | A clinicopathological study on combined hepatocellular and cholangiocarcinoma[END_REF][START_REF] Liu | Hepatic resection for combined hepatocellular and cholangiocarcinoma[END_REF][START_REF] Gentile | Surgical Treatment of Hepatocholangiocarcinoma: A Systematic Review[END_REF][START_REF] Zhou | Risk factors for combined hepatocellular-cholangiocarcinoma: A hospital-based case-control study[END_REF]. In Western countries, the rate of cirrhosis was up to 52% with HCV as the leading cause in Spain(43%) and USA(23%) and alcohol in France (40%) [START_REF] Jarnagin | Combined hepatocellular and cholangiocarcinoma: demographic, clinical, and prognostic factors[END_REF][START_REF] Sapisochin | Intrahepatic Cholangiocarcinoma or Mixed Hepatocellular-Cholangiocarcinoma in Patients Undergoing Liver Transplantation: A Spanish Matched Cohort Multicenter Study[END_REF][START_REF] Wells | Biphenotypic hepatic tumors: imaging findings and review of literature[END_REF][START_REF] Gigante | Combining imaging and tumour biopsy improves the diagnosis of combined hepatocellularcholangiocarcinoma[END_REF]. These data are consistent with a systematic review identifying cirrhosis in 51.7% of liver explants or surgical pieces [START_REF] Gentile | Surgical Treatment of Hepatocholangiocarcinoma: A Systematic Review[END_REF]. It seems that cHCC-CCA stands at the crossroad between iCCA (low rate of cirrhosis and HBV/HCV infection) and HCC (high rate of cirrhosis and HBV/HCV infection) in term of underlying liver disease.

Genetic landscape of cHCC-CCA

Whole-genome sequencing of liver cancer displaying biliary phenotype including cHCC-CCA reporsts a median number of 60 to 70 non-synonymous coding mutations per tumor(Table 2) [START_REF] Fujimoto | Wholegenome mutational landscape of liver cancers displaying biliary phenotype reveals hepatitis impact and molecular diversity[END_REF]. TERT promoter, TP53, ARID1A and ARID2 mutations are more frequent in cHCC-CCA, PBRM1, BAP1, KRAS, IDH1 and FGFR2 mutations in iCCA and CTNNB1 mutations in HCC. The high heterogeneity in term of technics and HCC-CCA classification of these studies needs to be underlined [START_REF] Liu | Whole-exome mutational and transcriptional landscapes of combined hepatocellular cholangiocarcinoma and intrahepatic cholangiocarcinoma reveal molecular diversity[END_REF][START_REF] Joseph | Genomic profiling of combined hepatocellular-cholangiocarcinoma reveals similar genetics to hepatocellular carcinoma[END_REF][START_REF] Sasaki | Mutational landscape of combined hepatocellular carcinoma and cholangiocarcinoma, and its clinicopathological significance[END_REF][START_REF] Moeini | Mixed hepatocellular cholangiocarcinoma tumors: Cholangiolocellular carcinoma is a distinct molecular entity[END_REF]. Genomic analysis also suggest an impact of viral hepatitis (HCV and HBV) on the genetic landscape of cHCC-CCA that seems closer to HCC than iCCA in term of genomic profiles and prevalence of TERT promoter mutations [START_REF] Fujimoto | Wholegenome mutational landscape of liver cancers displaying biliary phenotype reveals hepatitis impact and molecular diversity[END_REF]. The largest genetic study on cHCC-CCA was performed on 133 patients in Asia. TP53, TERT promoter, AXIN1, KMT2D, ARID1A were the leading mutations of cHCC-CCA, close to genomic alterations observed in HCC, even if the frequency of TERT promoter mutations (23%) seem lower than in HCC (40-60%) but higher than in iCCA (0-8%). The analysis of mutational signatures identified an exposure to aristolochic acid, aflatoxin B1 and hepatitis B. Epithelial mesenchymal transition, EpCAM, and KRT19 genes were mostly expressed in "combined" type cHCC-CCA with an enrichment of KRAS mutation. Xenobiotic and bile acid metabolism and overexpression of AFP, GPC3, and SALL4 were more represented in "mixed" type cHCC-CC according to the Allen Classification. The authors suggest that "mixed" type cHCC-ICC could be more similar to HCC and "combined" type cHCC-CCA more similar to iCCA [START_REF] Xue | Genomic and Transcriptomic Profiling of Combined Hepatocellular and Intrahepatic Cholangiocarcinoma Reveals Distinct Molecular Subtypes[END_REF].

Analysis of genetic landscape show that CLC has a different genetic profile compared to pure cHCC-CCA with more ARID1A and less TERT promoter mutation [START_REF] Sasaki | Cholangiolocellular Carcinoma With "Ductal Plate Malformation" Pattern May Be Characterized by ARID1A Genetic Alterations[END_REF]. Another genomic analysis confirms that CLC looks like a biliary-derived molecular entity harboring chromosomal stability, activation of TGFβ pathway with biliary features [START_REF] Moeini | Mixed hepatocellular cholangiocarcinoma tumors: Cholangiolocellular carcinoma is a distinct molecular entity[END_REF].

In term of tumor heterogeneity, comparison of the iCCA and HCC component confirms the monoclonal origin of cHCC-CCA but also shows a significant intratumor genetic heterogeneity overlapping with the morphological heterogeneity [START_REF] Xue | Genomic and Transcriptomic Profiling of Combined Hepatocellular and Intrahepatic Cholangiocarcinoma Reveals Distinct Molecular Subtypes[END_REF][START_REF] Wang | Whole-exome sequencing reveals the origin and evolution of hepato-cholangiocarcinoma[END_REF]. One study identified TERT promoter mutations in both HCC and iCCA components suggestive of an early event in carcinogenesis whereas mutations in other driver genes such as TP53 harbored intratumoral heterogeneity [START_REF] Joseph | Genomic profiling of combined hepatocellular-cholangiocarcinoma reveals similar genetics to hepatocellular carcinoma[END_REF].

In term of cell of origin, the disruption of p53 in mice promotes dedifferentiation of mature hepatocytes into nestin-positive progenitor cells that could give rise to HCC or iCCA under the influence or Wnt and Notch [START_REF] Katz | Disruption of Trp53 in livers of mice induces formation of carcinomas with bilineal differentiation[END_REF][START_REF] Tschaharganeh | p53dependent Nestin regulation links tumor suppression to cellular plasticity in liver cancer[END_REF]. Overexpression of nestin was identified in 81.3% of human cHCC-CCA and was associated with a poor clinical outcome [START_REF] Xue | Genomic and Transcriptomic Profiling of Combined Hepatocellular and Intrahepatic Cholangiocarcinoma Reveals Distinct Molecular Subtypes[END_REF]. Moreover, a cell line derived from cHCC-CCA can differentiate to both HCC and iCCA under different growth conditions [START_REF] Yano | A human combined hepatocellular and cholangiocarcinoma cell line (KMCH-2) that shows the features of hepatocellular carcinoma or cholangiocarcinoma under different growth conditions[END_REF][START_REF] Fujii | Genetic classification of combined hepatocellular-cholangiocarcinoma[END_REF]. These results are consistent with the hypothesis that cHCC-CCA can derive from hepatic progenitor cells that express markers of both lineages (hepatocytes and biliary cells) [START_REF] Roskams | Progenitor cells in diseased human liver[END_REF][START_REF] Yeh | Pathology of combined hepatocellular-cholangiocarcinoma[END_REF]. These data suggest that 1) cHCC-CCA is monoclonal deriving from a common cell of origin 2) cHCC-CCA genomic features may be more similar to HCC than iCCA even if some cHCC-CCA harbored genomic features closed to iCCA 3) risk factors can be associated specific genetic features in cHCC-CCA and 4) CLC has a different molecular profile close to iCCA.

Diagnosis

The diagnosis of cHCC-CCA is based on histology from biopsies or surgical specimens (Figure 2) [START_REF] Brunt | cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation[END_REF][START_REF] Sempoux | Combined hepatocellularcholangiocarcinoma and undifferentiated primary liver carcinoma[END_REF]. Immunohistochemical markers are not mandatory but could be helpful to better characterize PLC: hepatocyte markers (HepPar1, Alpha-fetoprotein and glypican-3); cholangiocytes markers (CK19, CK7) and "stem cells" markers (EpCAM, CK19, CD133) [START_REF] Brunt | cHCC-CCA: Consensus terminology for primary liver carcinomas with both hepatocytic and cholangiocytic differentation[END_REF][START_REF] Gigante | Combining imaging and tumour biopsy improves the diagnosis of combined hepatocellularcholangiocarcinoma[END_REF]. These markers should be considered in the context of morphological analysis, especially for the "stem cells markers" that could be expressed by all PLC. In pre-surgical setting, the performance of liver biopsy for the diagnosis of cHCC-CCA could be estimated to 48% of sensitivity and 100% of specificity [START_REF] Gigante | Combining imaging and tumour biopsy improves the diagnosis of combined hepatocellularcholangiocarcinoma[END_REF].

Sometimes the discordance between imaging and serum tumor markers (imaging suggestive of HCC with increased serum carbohydrate antigen or hypovascular nodule suggestive of iCCA with increased alpha-fetoprotein [AFP]) could rise the suspicion of a cHCC-CCA [START_REF] Ng | Combined hepatocellular-cholangiocarcinoma: a clinicopathological study[END_REF][START_REF] Liu | Hepatic resection for combined hepatocellular and cholangiocarcinoma[END_REF]. However, serum biomarkers alone are not reliable for the diagnosis of cHCC-CCA with elevation of serum CA19-9 and AFP observed only in 45% of the cases with also a limited specificity [START_REF] Wells | Biphenotypic hepatic tumors: imaging findings and review of literature[END_REF] [START_REF] Chen | Diagnostic Value of Serum Biomarkers in Combined Hepatocelluar-Cholangiocarcinoma[END_REF].

Even-though histology remains the gold standard for the diagnosis of cHCC-CCA, radiology (abdominal computed tomography (CT) or magnetic resonance imaging (MRI) with contrast agent injection) may help to suggest the diagnosis (Figure 2). Hallmarks of HCC (arterial phase hyper-enhancement [APHE] and washout) are observed in a minority of cHCC-CCA [START_REF] Wells | Biphenotypic hepatic tumors: imaging findings and review of literature[END_REF][START_REF] Gigante | Combining imaging and tumour biopsy improves the diagnosis of combined hepatocellularcholangiocarcinoma[END_REF][START_REF] Potretzke | Imaging Features of Biphenotypic Primary Liver Carcinoma (Hepatocholangiocarcinoma) and the Potential to Mimic Hepatocellular Carcinoma: LI-RADS Analysis of CT and MRI Features in 61 Cases[END_REF]. Nevertheless, recent studies using the American College of Radiology's liver imaging reporting and data system (LI-RADS) have reported misclassification of cHCC-CCA as HCC in 26% to 54% of cases when using major radiological features [START_REF] Mitchell | LI-RADS (Liver Imaging Reporting and Data System): summary, discussion, and consensus of the LI-RADS Management Working Group and future directions[END_REF][START_REF] Jeon | Combined hepatocellular cholangiocarcinoma: LI-RADS v2017 categorisation for differential diagnosis and prognostication on gadoxetic acid-enhanced MR imaging[END_REF]. Noticeably, 88% of these patients could be reclassified as malignant tumors but "non-HCC" (LI-RADS M category) after addition of ancillary features such as rim/peripheral arterial phase hyper-enhancement, progressive central enhancement, on portal venous and delayed phase images, predominantly peripheral washout appearance, liver surface retraction, biliary obstruction and marked diffusion restriction [START_REF] Mitchell | LI-RADS (Liver Imaging Reporting and Data System): summary, discussion, and consensus of the LI-RADS Management Working Group and future directions[END_REF]. The depiction of these features explain why the main differential diagnosis is often iCCA, and why performance of imaging is often insufficient [START_REF] Potretzke | Imaging Features of Biphenotypic Primary Liver Carcinoma (Hepatocholangiocarcinoma) and the Potential to Mimic Hepatocellular Carcinoma: LI-RADS Analysis of CT and MRI Features in 61 Cases[END_REF][START_REF] Hwang | Differentiating combined hepatocellular and cholangiocarcinoma from mass-forming intrahepatic cholangiocarcinoma using gadoxetic acid-enhanced MRI[END_REF][START_REF] Nishie | Detection of Combined Hepatocellular and Cholangiocarcinomas on Enhanced CT: Comparison with Histologic Findings[END_REF][START_REF] Willekens | Combined hepatocellular and cholangiocellular carcinoma presenting with radiological characteristics of focal nodular hyperplasia[END_REF][START_REF] De Campos | Combined hepatocellular carcinoma-cholangiocarcinoma: report of MR appearance in eleven patients[END_REF][START_REF] Fowler | Combined Hepatocellular and Cholangiocarcinoma (Biphenotypic) Tumors: Imaging Features and Diagnostic Accuracy of Contrast-Enhanced CT and MRI[END_REF]. The association of HCC features with CCA features (appearance of iCCA with portal venous invasion, or appearance of HCC with biliary dilation or enlarged lymph nodes) may be suggestive of the diagnosis. Finally, CEUS (contrast-enhanced ultrasound) also harbors an insufficient specificity for the diagnosis of cHCC-CCA, since tumors show non-specific association of various degree of heterogeneous arterial phase hyperhancement with washout [START_REF] Li | Combined hepatocellular carcinoma and cholangiocarcinoma (biphenotypic) tumors: clinical characteristics, imaging features of contrast-enhanced ultrasound and computed tomography[END_REF][START_REF] Sagrini | Imaging of combined hepatocellular-cholangiocarcinoma in cirrhosis and risk of false diagnosis of hepatocellular carcinoma[END_REF].

Imaging has a limited diagnostic performance alone with a sensitivity of only 48% and a specificity of 81% and the combination of imaging and biopsy could improve the sensitivity (60%) and specificity (82%) [START_REF] Gigante | Combining imaging and tumour biopsy improves the diagnosis of combined hepatocellularcholangiocarcinoma[END_REF]. Overall, radiology is fundamental to guide liver biopsy (especially possible multiple biopsies in heterogeneous tumors) and to perform tumor staging.

Treatments

Liver resection

Liver resection (LR) is currently the most effective curative-intent therapy for cHCC-CCA. According to state-of-the-art principle for oncologic liver surgery, liver resection aims to completely remove the lesion with adequate margins and with a sufficient liver remnant volume. This requires a multi-parametric evaluation of the patient, tumor and underlying liver disease [START_REF] Agrawal | Oncologic resection for malignant tumors of the liver[END_REF]. A resection margin >10 mm has been associated with a prolonged disease-free survival [START_REF] Ma | Importance of surgical margin in the outcomes of hepatocholangiocarcinoma[END_REF]. Major hepatectomy can be proposed if a sufficient liver remnant volume has been secured in order to limit the risk of postoperative liver failure [START_REF] Agrawal | Oncologic resection for malignant tumors of the liver[END_REF]. In patients with cirrhosis, evaluation of the degree of portal hypertension should also be performed as clinically significant portal hypertension represent absolute contraindications to major hepatectomy [START_REF] Cucchetti | Preoperative prediction of hepatocellular carcinoma tumour grade and micro-vascular invasion by means of artificial neural network: A pilot study[END_REF]. Furthermore, lymphatic pattern of tumor spread in cHCC-CCA requires a routine hilar lymphadenectomy [START_REF] Bagante | Surgical Management of Intrahepatic Cholangiocarcinoma in Patients with Cirrhosis: Impact of Lymphadenectomy on Peri-Operative Outcomes[END_REF]. The need for routine lymphadenectomy should currently restrict the use of the laparoscopic approach only to centers with extensive expertise both in liver surgery and laparoscopy [START_REF] Yoh | Oncological Resection for Liver Malignancies: Can the Laparoscopic Approach Provide Benefits?[END_REF].

A systematic review including 437 cHCC-CCA treated by LR reported a disease-free survival of 14.2 months in cHCC-CCA compared to 43.1 months in HCC and 17.8 months in iCCA with an overall survival of 37, 67 and 32 months respectively [START_REF] Gentile | Surgical Treatment of Hepatocholangiocarcinoma: A Systematic Review[END_REF]. Outcomes after liver resection for cHCC-CCA seems close to patients with iCCA and worse than patients with HCC mainly due to early tumor recurrence [START_REF] Jarnagin | Combined hepatocellular and cholangiocarcinoma: demographic, clinical, and prognostic factors[END_REF][START_REF] Liu | Hepatic resection for combined hepatocellular and cholangiocarcinoma[END_REF] even if a recent study identify no difference of outcomes after adjustment on cirrhosis and tumor size [START_REF] Holzner | Resection of Mixed Hepatocellular-Cholangiocarcinoma, Hepatocellular Carcinoma, and Intrahepatic Cholangiocarcinoma: A Western Center Experience[END_REF].

Liver transplantation

The role of liver transplantation (LT) for the treatment of small iCCA or cHCC-CCA remains controversial. A systematic review of retrospective studies for LT for cHCC-CCA reported a median disease-free survival of 14.2 months and a median OS of 37.1 months [START_REF] Gentile | Surgical Treatment of Hepatocholangiocarcinoma: A Systematic Review[END_REF]. These results were discouraging and, in many countries, cHCC-CCA is still a contraindication for LT.

In contrast, recent studies with similar inclusion criteria reported more positive outcomes. The first study conducted in Spain on 42 patients undergoing LT for HCC with an incidental diagnosis of HCC-CC or iCCA and stratified according to tumor size and number. The 5-years survival rates were similar between cHCC-CCA and HCC controls (78% vs 86%). Patients with multinodular or uninodular tumors larger than 2 cm had the worst outcomes [START_REF] Sapisochin | Intrahepatic Cholangiocarcinoma or Mixed Hepatocellular-Cholangiocarcinoma in Patients Undergoing Liver Transplantation: A Spanish Matched Cohort Multicenter Study[END_REF]. The second retrospective study analyzed patients treated by resection (n=26) or LT (n=95) for iCCA and cHCC-CCA <5cm developed on cirrhosis. Overall survival (67% at 5 years) and recurrence-free survival (75% at 5 years) were better in patients treated by LT than in patients treated by resection and small tumor. iCCA and cHCC-CCA patients had comparable survival [START_REF] De Martin | Analysis of Liver Resection versus Liver Transplantation on Outcome of Small Intrahepatic Cholangiocarcinoma and Combined Hepatocellular-Cholangiocarcinoma in the setting of cirrhosis[END_REF].

Recent retrospective data suggest that cirrhotic patients with cHCC-CCA transplanted have a better survival than patients resected if tumor size is <5 cm [START_REF] Sapisochin | Intrahepatic Cholangiocarcinoma or Mixed Hepatocellular-Cholangiocarcinoma in Patients Undergoing Liver Transplantation: A Spanish Matched Cohort Multicenter Study[END_REF][START_REF] De Martin | Analysis of Liver Resection versus Liver Transplantation on Outcome of Small Intrahepatic Cholangiocarcinoma and Combined Hepatocellular-Cholangiocarcinoma in the setting of cirrhosis[END_REF][START_REF] Lunsford | Propensity-Matched Analysis of Patients with Mixed Hepatocellular-Cholangiocarcinoma and Hepatocellular Carcinoma Undergoing Liver Transplantation[END_REF]. One of the main drawbacks of these studies is that cHCC-CCA was identified incidentally on the explant and data on intention-to-treat analysis of LT for cHCC-CCA diagnosed before inscription on the waiting list are lacking. A recent consensus concluded that there is not enough evidence to propose LT for cHCC-CCA but that this approach should be explored in clinical trials [START_REF] Sapisochin | Liver Transplantation for Cholangiocarcinoma and Mixed Hepatocellularcholangiocarcinoma[END_REF]. Moreover, liver transplantation should be also discussed according to each national guidelines.

Loco-regional treatments

The effectiveness of trans-arterial chemoembolization (TACE) on cHCC-CCA was analyzed in retrospective studies including a limited number of patients. TACE in 50 patients induced a partial response or stable disease in 70% of the cases, mainly in tumors with APHE with a median overall survival of 12.3 months [START_REF] Kim | Nonresectable combined hepatocellular carcinoma and cholangiocarcinoma: analysis of the response and prognostic factors after transcatheter arterial chemoembolization[END_REF]. Better outcomes were reported in a cohort of patients treated by TACE for recurrence after liver resection. As expected, cHCC-CCA with a with non-rim APHE pattern at imaging have a better radiological response rate (36% vs 0%) and survival (52.8 vs 12.4 months) compared to patients with rim APHE [START_REF] Yoon | Postresection Outcomes of Combined Hepatocellular Carcinoma-Cholangiocarcinoma, Hepatocellular Carcinoma and Intrahepatic Cholangiocarcinoma[END_REF][START_REF] Na | The effectiveness of transarterial chemoembolization in recurrent hepatocellular-cholangiocarcinoma after resection[END_REF]). Data about radio-embolization (SIRT) and chemotherapy on unresectable iCCA show that 22% of patients can be downstaged to surgical intervention [START_REF] Edeline | Radioembolization Plus Chemotherapy for First-line Treatment of Locally Advanced Intrahepatic Cholangiocarcinoma: A Phase 2 Clinical Trial[END_REF]. SIRT are associated with a 55% radiological response rate, 65% disease control rate with a median overall survival of 9.3 months in 21 patients suggesting a possible role of SIRT for cHCC-CCA [START_REF] Malone | Outcomes of Yttrium-90 Radioembolization for Unresectable Combined Biphenotypic Hepatocellular-Cholangiocarcinoma[END_REF].

Altogether, only few data are currently available to support the value of intra-arterial treatments in patients with cHCC-CCA, even if some retrospective data suggest a possible role in selected patients with tumor showing APHE.

Systemic treatments

Data about systemic treatments in unresectable cHCC-CCA are limited to few retrospective series testing the first-line treatment approved for advanced HCC (sorafenib) and CCA (gemcitabine/platinum regimens) [START_REF] Llovet | Sorafenib in advanced hepatocellular carcinoma[END_REF][START_REF] Rizvi | Cholangiocarcinoma -evolving concepts and therapeutic strategies[END_REF]. A multicentric Japanese study on 36 patients with unresectable cHCC-CCA analyzed different first-line systemic treatments. The median overall survival of the gemcitabine/cisplatin, fluorouracil/cisplatin and sorafenib was 11.9, 10.2 and 3.5 months respectively suggesting than sorafenib was associated with a reduced survival [START_REF] Kobayashi | Multicenter retrospective analysis of systemic chemotherapy for unresectable combined hepatocellular and cholangiocarcinoma[END_REF]. A French multicentric study included 30 patients treated by gemcitabine with oxaliplatine or cisplatin +/-bevacizumab. 8 patients (28.6%) had a partial response with a median progression free survival of 9.0 months and an overall survival of 16.2 months. [START_REF] Salimon | Gemcitabine plus platinum-based chemotherapy for first-line treatment of hepatocholangiocarcinoma: an AGEO French multicentre retrospective study[END_REF]. The largest series available is a monocentric cohort of 68 unresectable cHCC-CCA who received mainly gemcitabine-based regimen (57/68) with 23.5% gemcitabine +/-fluoropyrimidine and 60.3% gemcitabine with platinum. Overall survival was 11.5 months in patients receiving gemcitabine/platinum therapy and 9.6 months in the 7 patients treated with sorafenib alone [START_REF] Trikalinos | Systemic Therapy for Combined Hepatocellular-Cholangiocarcinoma: A Single-Institution Experience[END_REF]. Currently, no data in literature are available regarding the use of atezolizumab/bevacizumab, lenvatinib, cabozantinib and ramucirumab in cHCC-CCA. To summarize, systemic treatment based on gemcitabine/platinum regimens is the most widely used drug but is not supported by a high level of evidence. The role of sorafenib remains unknown.

Fibrolamellar carcinoma

FLC is a rare primary liver cancer derived from hepatocytes occurring in young adults (sex ratio 1/1) in normal liver (Figure 3) [START_REF] Lin | Fibrolamellar Carcinoma: A Concise Review[END_REF][START_REF] Lalazar | Fibrolamellar Carcinoma: Recent Advances and Unresolved Questions on the Molecular Mechanisms[END_REF][START_REF] Ramai | Fibrolamellar Hepatocellular Carcinoma: A Population-Based Observational Study[END_REF][START_REF] Mayo | Treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma: a national perspective[END_REF][START_REF] Njei | Prognosis of Patients With Fibrolamellar Hepatocellular Carcinoma Versus Conventional Hepatocellular Carcinoma: A Systematic Review and Meta-analysis[END_REF][START_REF] Edmondson | Differential diagnosis of tumors and tumor-like lesions of liver in infancy and childhood[END_REF]. It is characterized by eosinophilic polygonal cells and prominent nucleoli with fibrotic tissue surrounding tumor cells at histology [START_REF] Lin | Fibrolamellar Carcinoma: A Concise Review[END_REF][START_REF] Edmondson | Differential diagnosis of tumors and tumor-like lesions of liver in infancy and childhood[END_REF][START_REF] Craig | Fibrolamellar carcinoma of the liver: a tumor of adolescents and young adults with distinctive clinico-pathologic features[END_REF]. No risk factors of FLC development have been identified so far. Most of FLC are diagnosed before 40 years with a median age of diagnosis ranged from 20-29 years [START_REF] Mavros | A systematic review: treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma[END_REF][START_REF] Assi | Predictors of Outcome in Patients With Fibrolamellar Carcinoma: Analysis of the National Cancer Database[END_REF][START_REF] Honeyman | Detection of a recurrent DNAJB1-PRKACA chimeric transcript in fibrolamellar hepatocellular carcinoma[END_REF]. FLC are bigger in size (9-13 cm) with a higher rate of invasion of lymph node (43-46%) invasion compared to HCC [START_REF] Mayo | Treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma: a national perspective[END_REF][START_REF] Yamashita | Prognosis of Fibrolamellar Carcinoma Compared to Non-cirrhotic Conventional Hepatocellular Carcinoma[END_REF][START_REF] Stipa | Outcome of patients with fibrolamellar hepatocellular carcinoma[END_REF][START_REF] Mavros | A systematic review: treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma[END_REF]. The most frequent localization of metastasis are lung (50%), bone (19.2%), and brain (1.9%) [START_REF] Assi | Predictors of Outcome in Patients With Fibrolamellar Carcinoma: Analysis of the National Cancer Database[END_REF].

Physiopathology

At the molecular level, DNJBAB1-PRKCA fusion due to a focal deletion in the chromosome 19 is identified in almost all FLC and is considered as highly specific but not pathognomonic (Table 2) [START_REF] Honeyman | Detection of a recurrent DNAJB1-PRKACA chimeric transcript in fibrolamellar hepatocellular carcinoma[END_REF][START_REF] Cornella | Unique genomic profile of fibrolamellar hepatocellular carcinoma[END_REF][START_REF] Graham | DNAJB1-PRKACA is specific for fibrolamellar carcinoma[END_REF]. The same fusion was identified in a some intraductal oncocytic papillary neoplasms of the pancreas and bile duct(81,82)(82)(82) [START_REF] Vyas | DNAJB1-PRKACA fusions occur in oncocytic pancreatic and biliary neoplasms and are not specific for fibrolamellar hepatocellular carcinoma[END_REF]. A subset of HCC with fibrolamellar-like features occurred in non-cirrhotic liver but in older patients and was characterized by both BAP1 alterations and an aberrant activation of protein kinase A pathway due to a chromosome gain of PRKACA combined with a loss of PRKAR2A (the inhibitory regulatory subunit of PKA) [START_REF] Hirsch | BAP1 mutations define a homogeneous subgroup of hepatocellular carcinoma with fibrolamellar-like features and activated PKA[END_REF]. These tumors also expressed neuroendocrine and pancreatic markers underlining a potential origin from hepato-pancreatic progenitor. Finally, GNAS mutations leading to protein kinase A activation were observed in a subset of hepatocellular adenomas with a fibrous stroma [START_REF] Nault | GNASactivating mutations define a rare subgroup of inflammatory liver tumors characterized by STAT3 activation[END_REF]. All these data suggested that protein kinase A activation in the liver was associated with "fibrolamellar-like" features and underlined a link between the activation of protein kinase A and a hepato-pancreatic progenitor lineage. Finally, rare cases of FLC arising in patients with Carney complex were related to PRKAR1A germline inactivating mutations(Table 2) [START_REF] Graham | Fibrolamellar carcinoma in the Carney complex: PRKAR1A loss instead of the classic DNAJB1-PRKACA fusion[END_REF]. PRKCA from the fusion DNJBAB1-PRKCA has a conserved tyrosine kinase domain and an enhanced cAMP-stimulated protein kinase A activity. It leads to a constitutive activation of PKA pathway and promote malignant transformation of hepatocytes in mouse model(86,87)(87)(87) [START_REF] Engelholm | CRISPR/Cas9 Engineering of Adult Mouse Liver Demonstrates That the Dnajb1-Prkaca Gene Fusion Is Sufficient to Induce Tumors Resembling Fibrolamellar Hepatocellular Carcinoma[END_REF]. As DNAJB1-PRKACA fusion is a genetic footprint of FLC, it could be used to confirm the diagnosis of FLC using FISH or RT-PCR in clinical practice(80,88)(88)(88) [START_REF] Graham | Molecular testing for the clinical diagnosis of fibrolamellar carcinoma[END_REF].

Diagnosis

Most of the time diagnosis is made in a symptomatic patient with abdominal pain and weight loss [START_REF] Craig | Fibrolamellar carcinoma of the liver: a tumor of adolescents and young adults with distinctive clinico-pathologic features[END_REF]. Rarely, obstructive jaundice, gynecomastia in males, encephalopathy, ascites, acute liver failure, recurrent thrombophlebitis, anemia, hypoglycemia or Budd-Chiari syndrome can reveal FLC [START_REF] Torbenson | Review of the clinicopathologic features of fibrolamellar carcinoma[END_REF][START_REF] Ganeshan | Imaging features of fibrolamellar hepatocellular carcinoma[END_REF][START_REF] Lafaro | Fibrolamellar hepatocellular carcinoma: current clinical perspectives[END_REF]. Differential diagnosis consists of primary liver tumor with fibrosis such as some subtype of HCC (especially BAP1 mutated HCC), CCA or focal nodular hyperplasia.

The diagnosis of FLC could be suspected on CT and MRI taking into account the clinical context (young patient without chronic liver disease). FLC are usually large and lobulated heterogeneous lesions with a central stellate scar seen in 65-70% of the cases and with tumor calcifications and abdominal lymphadenopathy observed in half of the cases [START_REF] Ichikawa | Fibrolamellar hepatocellular carcinoma: imaging and pathologic findings in 31 recent cases[END_REF][START_REF] Friedman | Fibrolamellar hepatocellular carcinoma[END_REF]. On MRI, FLC show T1-weighted hypointensity and T2-weighted hyperintensity with a central area showing hypointense on both T1-and T2-weighted images [START_REF] Ichikawa | Fibrolamellar hepatocellular carcinoma: imaging and pathologic findings in 31 recent cases[END_REF]. FLC show heterogeneous hyperenhancement on arterial phase with a variable enhancement pattern on portal venous and delayed phases at CT scan and MRI [START_REF] Ganeshan | Imaging features of fibrolamellar hepatocellular carcinoma[END_REF]. Noticeably, FLC never contain fat, and do not invade hepatic or portal veins in contrast to classical HCC. FLC are also hypointense on the hepatobiliary phase using hepatobiliary contrast agents [START_REF] Palm | Imaging features of fibrolamellar hepatocellular carcinoma in gadoxetic acid-enhanced MRI[END_REF]. FLC don't usually produce detectable AFP and less than 10% of patients show increased AFP level above 200ng/mL [START_REF] Torbenson | Review of the clinicopathologic features of fibrolamellar carcinoma[END_REF]. Tumor and non-tumor liver biopsy is advised in most of the cases in clinical practice with the exception of patients eligible to surgery in front line whatever the results of the biopsy [START_REF] Lafaro | Fibrolamellar hepatocellular carcinoma: current clinical perspectives[END_REF][START_REF] Pérez-Guillermo | Cytologic aspect of fibrolamellar hepatocellular carcinoma in fine-needle aspirates[END_REF]. High rate of for CK7 and CD68 positive staining on liver samples and low rate of glypican-3 positive staining could differentiate FLC from regular HCC [START_REF] Hm | Fibrolamellar hepatocellular carcinoma: an immunohistochemical comparison with conventional hepatocellular carcinoma[END_REF][START_REF] Ross | Fibrolamellar Carcinomas are Positive for CD68[END_REF].

Treatment

In a systematic review including 575 patients, those treated with partial hepatectomy (55%) had 5-year overall survival reaching 70% [START_REF] Mavros | A systematic review: treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma[END_REF]. Liver resection was associated with a better overall survival (OS) in patients with FLC compared to patients with classical HCC (median OS of 84.9 vs. 42.9 months, respectively). However, no significant difference in 5-year survival could be observed when focusing on FLC and HCC patients without cirrhosis, suggesting that the difference observed in the overall population was likely related to the severity of the underlying liver disease [START_REF] Ramai | Fibrolamellar Hepatocellular Carcinoma: A Population-Based Observational Study[END_REF][START_REF] Njei | Prognosis of Patients With Fibrolamellar Hepatocellular Carcinoma Versus Conventional Hepatocellular Carcinoma: A Systematic Review and Meta-analysis[END_REF][START_REF] Assi | Predictors of Outcome in Patients With Fibrolamellar Carcinoma: Analysis of the National Cancer Database[END_REF]. Currently, liver resection remains the most effective curative-intent treatment option for FLC, aggressive initial surgical resection along with regional lymphadenectomy being advised [START_REF] Stipa | Outcome of patients with fibrolamellar hepatocellular carcinoma[END_REF][START_REF] Mavros | A systematic review: treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma[END_REF].

In contrast, results of LT are impaired by a high rate of tumor recurrence leading to a 5-year overall survival of 35% [START_REF] Mavros | A systematic review: treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma[END_REF]. However, the absence of selection criteria for patients treated by liver transplantation limits the conclusion drawn from these studies [START_REF] Njei | Prognosis of Patients With Fibrolamellar Hepatocellular Carcinoma Versus Conventional Hepatocellular Carcinoma: A Systematic Review and Meta-analysis[END_REF][START_REF] Mavros | A systematic review: treatment and prognosis of patients with fibrolamellar hepatocellular carcinoma[END_REF][START_REF] Pinna | Treatment of fibrolamellar hepatoma with subtotal hepatectomy or transplantation[END_REF]. Slightly better results were recently reported on 63 patients with an overall survival of 48% at 5 years [START_REF] Atienza | Liver transplantation for fibrolamellar hepatocellular carcinoma: A national perspective[END_REF]. As other indications, liver transplantation should be also discussed according to national guidelines. Patient with unresectable disease (20 to 25% at diagnosis) are treated with various combinations of systemic therapy, with or without locoregional therapies. The role of TACE or SIRT alone is also poorly studied in the literature. Chemotherapy regimens were 5-Fluorouracil (5-FU) +cisplatin or irinotecan, doxorubicin and gemcitabin+oxaliplatin but few patients exhibited radiological response(100). Sorafenib was associated with stable disease in 4 out of 9 patients and one patient harbored a complete response with anti-PD1 antibody(101). Moreover, aurora kinase A inhibitors showed a limited anti-tumor effect in a phase 2 clinical trial(102). Shutdown of PRKCA pathway and targeting the DNABJ1-PRKACA fusion is an appealing therapeutic avenue. If several therapeutic targets have been proposed in FLC such as inhibitor of the kinase pocket of the fusion protein or the combination of Hsp70 and MEK inhibitor(103)(104), currently no efficient targeted therapy has been validated.

Hepatic epithelioid Haemangioendothelioma

HEE is a rare vascular tumor developed on normal liver, characterized by epithelioid and histiocytoid vascular endothelial cells in a fibrotic stroma (Figure 4)(105). Tumor cells are positive for endothelial marker (facteur VIII related antigen, CD34 and CD31) at immunohistochemistry(105). Tumors cells likely invade pre-existing vascular channels including centrilobular veins at the periphery. Some risk factors have been suggested in the literature such as oral contraception, vinyl chloride, thorotrast, asbestos, or viral hepatitis even if the level of evidence is low(106,107). Hemangioendothelioma was described in 1982 as a vascular neoplasia affecting different organs with a prevalence of less than one per million(108-110). The most common organ involved are liver alone (21%), liver and lung (18%), lung alone (12%) and bone alone (14%) but any site in the body can be affected(106,111). HEE is more frequent in female (61% to 80%)(106,109). The clinical behaviour is heterogeneous from indolent to aggressive behavior(111).

Advances in knowledge of the physiopathology

Recurrent CAMTA1-WWTR1 fusion due to a translocation t(1;3)(p36.3;q25) with CAMTA1 as a calmodulin-binding transcription activator and WWTR1 (coding for TAZ) as a transcriptional coactivator is pathognomonic of HEE(Table 2)(112). In cellulo, CAMTA1-WWTR1 fusion results in nuclear localization of the fusion protein and lead to a constitutive activation of the hippo pathway through a TAZ-dependent transcriptomic program(113). Around 90% of HEE harbor the CAMTA1-WWTR1 fusion and this fusion was identified whatever the primary site of hemangioendothelioma (114). Moreover, rare YAP1-TFE3 fusion has been identified in HEE without CAMTA1-WWTR1 fusion(Table 2)(115,116). Detection of CAMTA1-WWTR1 fusion by FISH or RT-PCR or nuclear CAMTA1 expression at immunohistochemistry is useful to confirm the diagnosis of HEE as there have not been identified in other human tumors(116,117).

Diagnosis

A systemic review including 402 patients with HEE reported that 25% were asymptomatic whereas right upper quadrant pain (48.6%), hepatomegaly (20.4%) and weight loss (15.6%) were the most frequent symptom at diagnosis. Extrahepatic metastasis were observed in 36.6% of patients(107). HEE could be nodular or diffuse and nodular lesions are usually multiple and affect both lobes of the liver. A HEE should be suspected in front of multifocal nodules (88%), sometimes coalescent, or presence of nodules in subcapsular regions (up to 96%) with a capsular retraction (50 to 80%) at imaging(118-120). Presence of a ring enhancement at the tumor periphery on arterial phase is observed in 33% of patients with a target appearance on the portal venous phase in 69% of cases explained by a central fibrosis with a concentric layer of tumor cells and a peripheral avascular rim at histology. On MRI, HEE harbored a target appearance on the T2weighted sequences in 67% and on the diffusion-weighted sequences in 61% patients(120). Histology is the gold standard for the diagnosis of HEE with the help of immunohistochemistry (endothelial markers factor VIII related antigen, CD34 and CD31). The differential diagnosis with hepatic angiosarcoma is sometimes difficult to perform at histology and identification of CAMTA1-WWTR1 fusion could be useful to confirm the diagnosis of HEE(121).

Treatment

Therapeutic option in HEE should take into account tumor burden, extrahepatic metastasis, resectability, age and comorbidities. The pattern of progression (stability versus slow or rapid progression) should be also assessed before therapeutic decision.

A comprehensive review of the literature reported the use of LT in 44.8% of patients, followed by no treatment in 24.8%, chemotherapy or radiotherapy in 21% and liver resection in 9.4% (107). The results of LT for HEE were reported in multicentric database of 131 patients with a 5-year overall survival of 77.2%(122). Moreover, patients with extrahepatic metastasis could achieve prolonged survival after LT (up to 78% at 10 years)(123). Risk factors for recurrence after LT were macrovascular invasion, waiting time of less than 3 months and LN metastasis(124). Retrospective study has suggested that resection or LT in HEE could achieved the same outcomes with the limit of inclusion of more advanced stages in patients treated by LT(125). As HEE is often a bilobar disease rarely amenable to liver resection, LT might be the best option even for patients with extrahepatic metastasis (126).

In non-resectable or non-transplantable patients, different systemic treatments such as interferon alpha, thalidomide, doxorubicin, intra-arterial 5-fluorouracil,bevacizumab has been used in a very limited number of cases(121). Sorafenib used in a pilot study of 15 patients affected by HEE of different localization, the median progression-free survival was 6 months (127). In a subset of patients with indolent disease, careful follow-up can be an option, recent data reporting a 10-years OS of 41% in selected patients (128,129). As no systemic treatment is currently approved for the treatment of HEE, a better understanding of the biological consequences of CAMT1-WWTR1 fusion can be helpful in order to identify new targeted therapy.

Hepatic angiosarcoma

HAS is a high-grade aggressive mesenchymal malignancy defining a subtype of soft-tissue sarcoma composed of malignant endothelial tumoral cell of vascular or lymphatic origin developed mostly on normal liver (Figure 5). HAS is exceptional with an incidence estimated at 0.5-2.5 cases for 10,000,000 persons developed mostly in males(ratio 3:1)(130-132). In the sixties, 25% of HAS were associated to environmental risk factors such as vinyl chloride monomer, thorotrast, anabolic steroids and arsenic(133). HAS associated due to vinyl chloride monomer could be developed on cirrhosis (up to 20 to 43%)(134-136). With the control of exposure to vinyl chloride in workers in the 70s, the incidence of HAS declined(137,138).

Physiopathology

Overall, few data on molecular analysis is currently available. KRAS mutations have been described in sporadic cases as well as TP53 mutations in vinyl chloride related HAS and recently a ROS1-GOPC/FIG fusion has been identified in one HAS(139-141).

Diagnosis

Most of the time, patients with HAS have symptoms at presentation such as abdominal pain, fatigue, weight loss, hepatosplenomegaly, ascites, jaundice, and anemia. The intraperitoneal rupture of HAS was reported in 15-27% of patients(142). HAS has a very aggressive behavior and poor prognostic factors are older age, large tumor size and high Ki-67 index(130,132). 219 patients analyzed in a recent systematic review have an average age of 56.7 years and 31.5% of distant metastasis. The median overall survival time was 6 months, with a 2-year survival of 17.3%(143).

At contrast-enhanced imaging, HAS is usually multifocal and with heterogeneous patterns such as a progressive enhancement without washout at the portal and delayed phase. Progressive centripetal or diffuse "flash-fill" enhancement pattern ("reverse haemangioma") with centrifugal enhancement have also been reported(135,144). HAS often contain hemorrhagic area resulting in heterogeneous lesions on MRI with hyperintense zones on T1WI and hypointense on T2WI(144).

Some controversy exists about the performance of liver biopsy and about a potential high risk of bleeding (136,142,145). However, histology remains the gold standard for the diagnosis of HAS and liver biopsy is required to confirm the diagnosis(132). HAS is heterogeneous at histology ranging from well-defined anastomotic vessels (vasoformative) to solid sheets of epithelioid or spindled cells without vasoformation with different patterns sometimes mixed in the same tumors(130). HAS expresses ERG and endothelial markers as CD31 and CD34 at immunohistochemistry(146).

Treatment

Surgical resection seems the best therapeutic option offering a median survival between 17 and 19 months(142,147). All the studies about LT confirmed the limited survival (around 6 months) with most of patients dying from tumor recurrence explaining why HAS is a contraindication to LT (148,149). It is important to note that only 30% of patients had a known pre LT diagnosis of HAS(125).

Transarterial embolization is frequently used to treat tumor bleeding with a limited impact on survival(143). There is no approved chemotherapy regimen for non-resectable liver HAS. ESMO guidelines on Sarcomas reports that angiosarcomas in general are sensitive to taxanes, reporting gemcitabine as an alternative alone or in combination with docetaxel(150). In a phase II trial including three primary liver angiosarcomas in patients with metastatic or unresectable disease weekly paclitaxel achieved a progression-free survival rates of 74% and 45% at 2 and 4 months respectively, with a median overall survival of 8 months(151). Palliative chemotherapy such as 5-FU with doxorubicin or ifosfamide, carboplatin, bevacizumab or sorafenib have been reported mostly in case reports or small series with limited radiological response and poor survival(132). Due to the rarity of this cancer the management of HAS should be made in centers with multidisciplinary expertise on sarcomas.

Conclusion

Despite several advances in the last decades mainly in the field of physiopathology, rare PLC suffer from their condition of orphan diseases with pitfalls in term of diagnosis and limited availability of dedicated prospective collection of clinical data and limited cases to clinical trials. Moreover, grants dedicated to these PLC are lacking and pharmaceutical companies are rarely interested in the development of new drugs for these patients. In order to bypass these limitations, large international consortiums are needed in the future to rise grant to run large prospective cohort and better define rare PLC in term of physiopathology and clinical behavior. This cooperative network will be also the basis of future clinical trials.

KEY POINTS:

1) Recent consensus has reclassified pure cholangiolocarcinoma in CCA whereas cHCC-CCA are characterized histologically by the presence of two distinct morphological patterns in the same lesion 2) A unique genetic alteration drives the pathogenesis of fibrolamellar carcinoma (DNJBAB1-PRKCA fusion) and hepatic haemangioendothelioma (CAMTA1-WWTR1 fusion) 3) Combination of evocative imaging followed by histological evidence, mainly using tumor and non-tumor biopsy, are required for the diagnosis of rare PLC 4) Liver resection is the main treatment of rare PLC when feasible 5) No systemic or locoregional therapies are currently validated in the treatment of any of unresectable PLC 6) Liver transplantation is validated for hepatic hemangioendothelioma even in a metastatic setting whereas is still an area of research for small cHCC-CCA We figured the main genetic alterations, clinical, histological and pathological and radiological features as well the treatment available of cHCC-CCA

Figure 2: histological and radiological features of hepatocholangiocarcinoma

In the upper panel we represented classical cHCC-CCA (upper panel, left) with the HCC (positive for Glypican 3) and CCA (positive for CK7) components as well as intermediate cell carcinoma (positive for CD133) (upper panel, right)

In the middle panel we represented HCC with stem cell features (middle panel, left) at immunohistochemistry (positive for Glypican 3 and for CK19) and cholangiolocarcinoma recently reclassified as iCCA (middle panel right).

In the lower panel, we figured an example of a MRI of cHCC-CCA with a well-delineated heterogeneous lesion with capsular retraction. The lesion harbored progressive delayed enhancing areas mixed with areas with arterial enhancement and washout.

Figure 3: main characteristics of fibrolamellar carcinoma

We figured the main genetic alterations, clinical, histological and pathological and radiological features as well the treatment available of FLC

Figure 4: main characteristics of hepatic haemangioendothelioma

We figured the main genetic alterations, clinical, histological and pathological and radiological features as well the treatment available of HEE

Figure 5: main characteristics of hepatic angiosarcoma

We figured the main genetic alterations, clinical, histological and pathological and radiological features as well the treatment available of HAS

Figure 1 :

 1 Figure 1: main characteristics of hepatocholangiocarcinoma

  clinical trial only TACE: Not resectable, hypervascular and no metastasis Gemcitabin/platinum or sorafenib: not resectable and hypovascular or with metastasis Genetic alterations TERT promoter 20 to 50% TP53 25 to 49% AXIN1 10% ARID1A 8 to 15% CTNNB1 6 to 10% IDH1 5% KRAS 5% Epidemiology and risk factors 2-5% of primary liver cancer Predominance of male Cirrhosis: 20 to 50% Risk factors: HBV, HCV, alcohol Imaging Major features Delayed enhancing areas mixed with areas with arterial enhancement and washout Capsular retraction, bile duct dilation and lymph nodes in HCClike lesions Venous invasion in iCCA-like lesions Histology Major features Presence of hepatocytic and cholangiocytic histology mixed with a transition or separated areas within the same tumor Hepato-Cholangio carcinoma HCC component CCA component

Figure 2 ImagingFigure 4 TreatmentFigure 5 Treatment

 245 Figure 2

Table 1 : recent data on risk factors of hepatocholangiocarcinoma

 1

Table 2 : genomic alterations in rare primary liver cancers

 2

	Study	Classification	Type of analysis	N patients Subtypes	Fibrosis (F3-F4)	Somatic genetic alterations
				Hepatocholangiocarcinoma
	Cazals-Hatem 2004(154)	Lisa et Allen 1949	Target sanger sequencing	14 mixed, 1 fibrolamellar HCC 3 collision tumors	3/15	TP53
	Fujimoto 2015(23)	WHO 2010	WGS and RNA-seq	30 Liver cancer with biliary phenotype 7cHCC-CCA +2CLC	4/9	TERT promoter 53%, PBMR1 20%, ARID2 27%
	Sasaki 2017(26)	WHO 2010	Target sanger sequencing + IHC	53 mixed tumors 4 CT, 4 TS, 20 INT, 25 CLC	38/53	cHCC-CCA: TERT 50%, TP53 25%, KRAS 50% ARID1A 0% Intermediate: TERT 42%, TP53 58%, , KRAS 5%, ARID1A 11%
	Moeini 2017(27)	WHO 2010	Microarray, DNA copy number, WES	18 mixed tumors 6 CLC / 8SC / 4CT	10/18	CLC: TP53 and IDH1 cHCC-CCA: TP53, TERT promoter, BRAF, FGFR2-BICC1 fusion
	Liu 2018(24)	WHO 2010	WGS, WES and RNA-seq	4 cHCC-CCA not specified	NA	TP53, CTNNB1 and ARID1A
	Wang 2018(30)	WHO 2010	WES	7 cHCC-CCA	NA	TP53 and ARID2
	Xue 2019(28)	Lisa et Allen 1949	WES, WGS, RNA-seq,	121 tumors: 6 separate type, 56 combined type, 59 mixed type.	54/115	TP53 49% , TERT promoter 23%, AXIN 10%, KMT2D 9%, KEAP1 8%, ARID1A 8%, RB1 8%, CTNNB1 6%, IDH1 5%
	Joseph 2019(25)	Consensus 2019	Target next-generation sequencing	20CT	15/18	TP53 (80%), TERT (70%), ARID1A (15%), CTNNB1 (10%), AXIN1 (10%), KRAS (5%)
	Sasaki 2019(29)	Consensus 2019	Target sequencing + IHC	9 CT	6/9	TP53 (66%), TERT promoter (33%), KRAS (22%)
				Fibrolamellar carcinoma
	Honeyman
	2014	NA	RNA seq	15 FLC	0	DNAJB1-PRKACA fusion (100%)
	(78)
	Cornella 2015(79)	NA	FISH WES	78 FLC	0	DNAJB1-PRKACA fusion (79%) BRCA2 (4.2%)
	Graham 2015(80)	NA	RT-PCR FISH	26 FLC	0	DNAJB1-PRKACA fusion (100%)
	Graham 2018(85)	NA	FISH NGS	3 FLC without DNAJB1-PRKACA fusion	0	PRKAR1A (100%) in patients with Carney syndrome and FLC
	Graham 2018(155)	NA	FISH	104 typical FLC, 12 probable FLC and 9 unlikely FLC	0	99% DNAJB1-PRKACA fusion in typical, 75% in probable and 0% in unlikely FLC
				Hepatic haemangioendothelioma
	Tanas 2011 (112)	NA	RNA seq FISH	47 haemangioendothelioma (hepatic and non-hepatic)	0	89% WWTR1-CAMTA1 fusion
	Errani 2011(114)	NA	FISH	17 haemangioendothelioma (hepatic and non-hepatic)	0	100% WWTR1-CAMTA1 fusion
	Antonescu 2013(115)	NA	FISH	10 haemangioendothelioma without WWTR1-CAMTA1	0	100% YAP1-TFE3 fusion (in tumors without WWTR1-CAMTA1 fusion)
	Flucke 2014(156)	NA	FISH RT-PCR	35 haemangioendothelioma (hepatic and non-hepatic)	0	94% WWTR1-CAMTA1 and 6% YAP1-TFE3 fusion
	Patel 2015(116)	NA	RT-PCR	18 haemangioendothelioma (hepatic and non-hepatic)	0	78% WWTR1-CAMTA1 and 6% YAP1-TFE3 fusion

Molecular alterations of HAS were not represented as very few data are currently available in the literature CLC = cholangiolocarcinoma, WES = whole exome sequencing, WGS = whole genome sequencing, IHC = immunohistochemistry, CT = classical type, TS = typical subtype, INT = intermediate subtype, CLC = cholangiocellular subtype, SC= stem cell subtype, EMT= epithelio-mesenchymal transition


Marc Pineton De Chambrun

Fleur Cohen-Aubart

Dirk Donker

Pierre-Louis Cariou

Charles-Edouard Luyt

Alain Combes

Zahir Amoura

SARS-CoV-2 Induces Acute and Refractory Relapse of Systemic Capillary Leak Syndrome (Clarkson's Disease)

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

TITLE:( 7 1

 7 SARS-CoV-2-induces acute and refractory relapse of systemic capillary leak syndrome 1 Marc Pineton de Chambrun 1,2 , MD, MSc ; Fleur Cohen-Aubart 2 , MD, PhD ; Dirk W. 4 Donker 1 , MD, PhD; Pierre-Louis Cariou, MD 2 ; Charles-Edouard Luyt 1 , MD, PhD ; Alain 5 Combes 1 , MD, PhD and Zahir Amoura 2 , MD, MSc. 6 Sorbonne Université, APHP, Institut de Cardiométabolisme et Nutrition (ICAN), Hôpital La 8 Pitié-Salpêtrière, service de médecine intensive-réanimation, Paris, France 9 2 Sorbonne Université, Assistance Publique-Hôpitaux de Paris (APHP), Hôpital de la Pitié-10 Salpêtrière, service de médecine interne 2, maladies auto-immunes et systémiques rares, Dr Marc Pineton de Chambrun, MD, MSc, Service de Médecine 14 Intensive Réanimation et Service de Médecine Interne 2, Hôpital La Pitié-Salpêtrière, 47-83, 15 boulevard de l'Hôpital, 75651 Paris Cedex, France; e-mail: marc.dechambrun@gmail.com; 16 marc.pinetondechambrun@aphp.fr Tel: +33 (0)1 84 82 76 32, +33 (0to the data and a role in writing the manuscript. 23 The authors have no conflict of interest to declare 24 © 2020 published by Elsevier. This manuscript is made available under the CC BY NC user license https://creativecommons.org/licenses/by-nc/4.0/ Version of Record: https://www.sciencedirect.com/science/article/pii/-leak syndrome (SCLS), also known as Clarkson's disease, is a 3 rare condition characterized by recurrent episodes of capillary hyperpermeability in the 4 context of a monoclonal gammopathy 1 . We have previously shown that prophylactic 5 treatment with intravenous immunoglobulins (IVIg) significantly reduces relapse and 6 improve survival 2,3 . SCLS episodes are thought to have an infectious trigger, especially 7 mediated by viruses and a flu-like viral syndrome was reported in more than half of the 8 episodes in a large cohort of Clarkson's disease flares 4 . 9 A 45-year-old woman, with a 7-year history of IgG Kappa monoclonal gammopathy-10 associated SCLS, was recently admitted to our hospital for a planned immunoglobulin 11 infusion. She regularly received IVIg since her diagnosis of Clarkson's disease at an initial 12 dosage of 2g/kg, with progressive tapering to 0.5g/kg of body weight monthly. This 13 preventive treatment protected her from having any relapse. When she was admitted in 14 March 2020 she complained about nausea and vomiting and a 10 kg increase of body 15 weight. She had no fever or any respiratory symptoms, but hypotension (80/40 mmHg) with 16 elevated heart rate (110 bpm). Laboratory findings were typical for an acute episode 17 (hemoglobin 19.1 g/dL, proteinemia: 42g/L). Evolution was unfavorable with severe 18 hypovolemic shock, multiple organ failure and 4-limb compartment syndrome cumulating 19 into refractory cardiac arrest. SARS-CoV-2 PCR turned out to be positive as sampled by 20 tracheal aspiration. 21 The pathophysiology of SCLS is unknown. Whether the monoclonal component 22 contributes to the pathogenesis of the disease and the mode of action of IVIg remains 23 elusive. Still, the role of viruses as a trigger for acute relapses of the disease has repeatedly been described, as holds particularly for the influenza virus. SARS-CoV-2, a novel coronavirus 1 that spread in early 2020 from the region of Wuhan in China is characterized mainly by a 2 severe acute respiratory distress syndrome 5 . In this patient, the viral infection, although 3 poorly symptomatic, can be considered as the trigger of the relapse. 4 We believe that this report contributes to our mechanistic understanding of several 5 urgent considerations. Firstly, our patient died from a severe episode triggered by a SARS-6 CoV-2 infection without demonstrating neither any signs of severe SARS-CoV-2 infection. 7 Secondly, she did not experience any acute relapse during the previous 7 years while under 8 preventive treatment with IVIg, yet she died after being infected with this new pandemic 9 virus. Obviously, IVIg preparations contain virus-specific immunoglobulins that may protect 10 patients with Clarkson's disease against seasonal viral infections. Yet, in the setting of this 11 new pandemic virus, the protection generally granted by IVIg may vanish because of the lack 12 of SARS-CoV-2 specific immunoglobulins in available preparations. Thirdly, conversely an 13 additional aspect of the immunoglobulin treatment in our patient might have been 14 insufficient to prevent such a virulent virus, i.e. the individual dosage. Therefore, an 15 intensified IVIg treatment using increased dosages in all Clarkson's disease patients (2g/kg 16 monthly) should be considered at least during the beginning of the pandemic. Lastly, SCLS 17 patients should be considered at very high risk for an acute relapse while facing this new 18 coronavirus and maximal isolation should imperatively be advocated. B, Thompson D, Horwith M, Luckey EH. Cyclical edema and shock due to 2 increased capillary permeability. The American Journal of Medicine 1960;29(2):193-216.

3 2 .

 2 Pineton de Chambrun M, Gousseff M, Mauhin W, et al. Intravenous Immunoglobulins 4 Improve Survival in Monoclonal Gammopathy-Associated Systemic Capillary-Leak 5 Syndrome. Am J Med 2017;130(10):1219.e19-1219.e27. 6 3. Gousseff M, Arnaud L, Lambert M, et al. The systemic capillary leak syndrome: a case 7 series of 28 patients from a European registry. Ann Intern Med 2011;154(7):464-471.

8 4 .

 4 Pineton de Chambrun M, Luyt C-E, Beloncle F, et al. The Clinical Picture of Severe 9 Systemic Capillary-Leak Syndrome Episodes Requiring ICU Admission. F, Yu T, Du R, et al. Clinical course and risk factors for mortality of adult inpatients 12 with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet 2020; 13


MD, MSc Fabien Picard
email: fabien.picard@aphp.fr

MD Anastasia Sokoloff

MD Vincent Pham

MD Marine Diefenbronn

MD Driss Laghlam

MD Gabriel Seret

MD, PhD Olivier Varenne

MD Florence Dumas

MD, PhD Alain Cariou

Safety and benefit of Glycoprotein IIb/IIIa inhibitors in out of hospital cardiac arrest patients treated with percutaneous coronary intervention

Keywords: Cardiac-arrest, acute coronary syndrome, glycoprotein IIb/IIIa inhibitor, bleeding, stent thrombosis Acute coronary syndrome PCI: Percutaneous coronary intervention OHCA: Out-of-hospital cardiac arrest STEMI: ST-elevation myocardial infarction GPi: Glycoprotein IIb/IIIa inhibitors BMI: Body mass index ORs: Odds-ratio CI: Confidence interval

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Acute coronary syndromes (ACS) are the leading cause of cardiac arrest [START_REF] Nolan | European Resuscitation Council and European Society of Intensive Care Medicine Guidelines for Postresuscitation Care 2015: Section 5 of the European Resuscitation Council Guidelines for Resuscitation 2015[END_REF]. European guidelines recommend urgent coronary angiography in a view for primary percutaneous coronary intervention (PCI) in survivors of out-of-hospital cardiac arrest (OHCA) [START_REF] Nolan | European Resuscitation Council and European Society of Intensive Care Medicine Guidelines for Postresuscitation Care 2015: Section 5 of the European Resuscitation Council Guidelines for Resuscitation 2015[END_REF][START_REF] Bougouin | Should We Perform an Immediate Coronary Angiogram in All Patients After Cardiac Arrest?: Insights From a Large French Registry[END_REF][START_REF] Noc | Invasive coronary treatment strategies for out-of-hospital cardiac arrest: a consensus statement from the European association for percutaneous cardiovascular interventions (EAPCI)/stent for life (SFL) groups[END_REF]. A primary PCI strategy is recommended in patients with resuscitated cardiac arrest and an ECG consistent with STEMI (Class I), and urgent angiography (and PCI if indicated) should be considered in patients with resuscitated cardiac arrest without diagnostic ST-segment elevation but with high suspicion of ongoing myocardial ischemia (Class IIa) [START_REF] Ibanez | ESC Guidelines for the management of acute myocardial infarction in patients presenting with STsegment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC)[END_REF].

Nevertheless, ACS is a peculiar situation in terms of thrombotic and hemorrhagic balance. Indeed, OHCA patients are at higher risk of thrombosis and bleeding due to potential resuscitation traumatisms, invasive monitoring, and post-resuscitation syndrome [START_REF] Picard | The balance of thrombosis and hemorrhage in STEMI patients with or without associated cardiac arrest: An observational study[END_REF]. There is no specific recommendation regarding anti-thrombotic therapy in this specific population. In general practice, the use of Glycoprotein IIb/IIIa inhibitors (GPi) is usually considered for bailout situations (large thrombus, slow-or no-reflow) or thrombotic complications in patients with ACS (Class IIa) [START_REF] Ibanez | ESC Guidelines for the management of acute myocardial infarction in patients presenting with STsegment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC)[END_REF], although this strategy has not been tested in a randomized trials. Nevertheless, the use of GPi is related to increased risk of bleeding, that could overcome potential benefit in high-bleeding risk populations such as OHCA patients. Indeed, data regarding the use of GPi in OHCA patients undergoing PCI is scarce [START_REF] Jiménez-Brítez | Safety of glycoprotein IIb/IIIa inhibitors in patients under therapeutic hypothermia admitted for an acute coronary syndrome[END_REF]. Therefore, we sought to evaluate the benefit and safety of GPi use in OHCA patients requiring PCI.

Methods

Study design and population

This was an observational, single-center, retrospective study of consecutive patients treated for an OHCA from cardiac cause with PCI between January 2007 and December 2017, that was conducted at Cochin Hospital, an academic tertiary center. In this analysis, all consecutive patients presenting with an OHCA from cardiac cause treated with PCI and stent implantation during the study period were included. Exclusion criteria included age<18-yearold, and patients that did not have stent implantation. Two groups were defined according to GPi administration. The study was conducted according to the Declaration of Helsinki. As this was a retrospective analysis conducted per institutional guidelines for data security and privacy, a waiver of consent was granted. Data were anonymized by authors prior to analysis.

Baseline and procedural characteristics

Baseline demographics, medical history, cardiac catheterization data and in-hospital outcomes were abstracted from medical charts. Patients were treated with aspirin and heparin prior to hospital admission or during the procedure. The use of GPi was at the operator's preference but usually considered for bailout situations (large thrombus, slow-or no-reflow) or thrombotic complications. Tirofiban and abciximab were the two GPi used, according to hospital protocol and recommended dosage. The arterial access site (femoral or other), although not recorded in the present analysis was mainly femoral due to local protocol but left at the operators' discretion. The use of clopidogrel, ticagrelor or prasugrel was also left at the operators' discretion. After PCI, all patients were transferred to Intensive Care Unit (ICU).

Aspirin was administered intravenously during pre-hospital transfer when signs of STelevation myocardial infarction on electrocardiogram or per-procedure when not administered earlier. P2Y12 inhibitors were administered through nasogastric tube either per-procedure or upon arrival in ICU.

Clinical endpoints and definitions

The primary endpoints were the occurrence of in-hospital acute stent thrombosis and the incidence of in-hospital bleeding events. ST was defined according to the Academic Research Consortium for trials involving stent [START_REF] Cutlip | Clinical end points in coronary stent trials: a case for standardized definitions[END_REF]. A ST was definite when acute coronary syndrome with angiographic or pathological confirmation of thrombus was provided, probable when unexplained death within 30 days or MI involving target vessel territory without angiographic confirmation was diagnosed. In cardiac arrest patients, probable stent thrombosis was determined using serial troponin measurements, serial 12-lead ECGs and unexplained hemodynamic deterioration without other clear cause for cardiac arrest patients and without angiographic confirmation of stent thrombosis. Repeated coronary angiography was usually performed in the department in case of recurrent ST-segment elevation, abnormal troponin rise after the acute phase or hemodynamic degradation associated with ECG modifications.

Bleedings complications were defined using the Bleeding Academic Research Consortium (BARC) [START_REF] Mehran | Standardized Bleeding Definitions for Cardiovascular Clinical Trials: A Consensus Report From the Bleeding Academic Research Consortium[END_REF]. Type 3 and 5 of BARC classification were considered. Type 3 encompassed: 3a: Overt bleeding plus hemoglobin drop of 3 to <5 g/dL or any transfusion with overt bleeding; 3b: overt bleeding plus hemoglobin drop ≥ 5 g/dL or cardiac tamponade or bleeding requiring surgical intervention for control or bleeding requiring intravenous vasoactive agents and 3c:

Intracranial hemorrhage, subcategories confirmed by autopsy or imaging or lumbar puncture or intraocular bleed compromising vision. Type 5 included fatal bleeding, ie. 5a: probable fatal bleeding, no autopsy or imaging confirmation but clinically suspicious; 5b: Definite fatal bleeding overt bleeding or autopsy or imaging confirmation.

Statistical analysis

Continuous variables were expressed as mean ± standard deviation when normally distributed and as median [inter-quartile range] otherwise. Categorical variables were expressed as count and percentage. The associations between categorical variables were assessed using a chisquare test (or Fisher exact test when appropriate) and continuous variables compared with Student t-test. Multivariate logistical regression was developed to assess the association between baseline characteristics of interest (pre-specified patient, lesion and procedural variables) and the use of GPi. In addition, univariate and multivariate logistical regression were developed to assess the association between baseline characteristics of interest (prespecified patient, lesion and procedural variables) including GPi use and the association with the occurrence of major bleeding. Candidate covariates that showed marginal associations to outcome on univariate testing (p ≤ 0.15), up to a maximum of a tenth of the number of events, in order to prevent overfitting, were included in our multivariate analysis. Odds ratios (ORs) are presented with 95% confidence interval (CI). Statistical significance was defined at a level of α≤0.05. Statistical analyses were carried out using SPSS package v23.0 (Chicago, IL, USA).

Results

Population and procedure

Between January 2007 and December 2017, 385 patients were treated with PCI following OHCA without reaching exclusion criteria (Figure 1). GPi were administrated in 41.3% of cases (159 patients). Patients baseline characteristics and clinical presentation are described in Table 1. 377 (97.9%) patients were comatose and benefited from mechanical ventilation under sedation. There was no major difference among the two populations. Between our two groups, patients in the GPi group had less hypertension (26.4% vs. 46.7%, p<0.001) as well as less prior PCI (9.4% vs. 24.9%, p<0.001). Initial clinical presentation also differed on two criteria, as GPi patients presented more often an initial shockable rhythm (96.3% vs. 76.8%, p=0.01), and ST-segment elevation was more often present (83.9% vs. 64.6%, p<0.001).

Therapeutic hypothermia was performed in 86.0% of the patients over the first 24 hours according to local protocol.

Concerning procedural characteristics, the culprit coronary artery was more often the left anterior descending artery in the GPi group (64.7% vs. 53.1%, p<0.0001). GPi patients presented more often a TIMI 0 or 1 before PCI (79.9 % vs. 58.0%, p<0.001) and operators were more likely to perform thromboaspiration (63.9% vs. 28.9%, p<0.001). No reflow during procedure was also more often described in GPi patients (8.9% vs. 1.8%, p=0.001).

Regarding peri-procedural medical treatment, antiplatelet therapy was well balanced between the two groups. Procedural characteristics are summarized in Table 2.

Determinants of Glycoprotein IIb/IIIa inhibitor usage

GPi were used in 41.3% of patients. Multivariate analyses of factors associated with administration of GPi are showed in Table 3. Using multivariate regression, younger ager (OR 0.98(0.96-1.00), p=0.04), the absence of prior PCI (OR: 0.49 (0.25-0.96), p=0.04), thromboaspiration (OR: 2.89 (1.78-4.70), p<0.0001) and a TIMI 0 or 1 flow before PCI (OR: 2.01 (1.17-3.45), p=0.01) were the only parameters associated with use of GPi during the procedure. Gpi use was consistant over the study timeframe (Supplemental Figure 1).

Outcomes, thrombotic and bleeding events

In-hospital mortality was high, up to 47.8% of the patients. Bleeding stage 3 or 5 of BARC classification affected 22.1% of patients, and acute stent thrombosis 9.1% of patients. Inhospital outcomes are summarized in Table 4 and Figure 2. Bleeding events rates were significantly different between the two population. GPi patients were more likely to present any bleeding complications (33.3% vs. 19.6%, p=0.002), as well as BARC 3-5 bleedings (28.3% vs. 16.8%, p=0.007). On the other hand, there were no significant differences concerning ST or in-hospital mortality (p=0.10 and p=0.68, respectively).

Bleeding events predictors

Uni-and multi-variate analysis of risk factors associated with major bleeding (BARC 3-5 of the BARC classification) are described in Table 5. Using univariate analysis, dual antiplatelet therapy associating aspirin to a more potent P2Y12 inhibitor (ticagrelor or prasugrel) (OR 1.48 (0.91-2.41), p=0.12), the use of thromboaspiration (OR: 1.45 (0.90-2.37), p=0.13), lowflow duration (OR: 1.01 (1.00-1.03), p=0.08), and total length of implanted stent (OR: 0.99 (0.97-1.00), p=0.10) tended to be associated with increased major bleeding events. The use of GPi (OR: 1.95 (1.20-3.19), p=0.007) and mechanical support devices (ECMO, Impella or IABP) (OR:1.86 (1.12-3.10), p=0.02) were the only significant predictors of major bleeding.

Using multivariate analysis, the administration of GPi remained a significant predictor of higher risk of major bleeding event (OR: 1.81 (1.06-3.08), p=0.03), as well as mechanical support device use (OR: 2.03 (1.14-3.62), p=0.02) and dual antiplatelet therapy associating aspirin to a more potent P2Y12 inhibitor (ticagrelor or prasugrel) (OR: 1.99 (1.15-3.46), p=0.01).

Discussion

The main finding of this study was that the use of GPi in the specific context of OHCA patients associated with ACS is statistically associated with increased risk of bleeding events (any or major), without any significant differences for stent thromboses or in-hospital mortality.

Glycoprotein IIb/IIIa receptor activation is the common final link of platelet aggregation.

Several studies suggest that the use of GPi may reduce thrombotic complications in patients undergoing primary PCI [START_REF] Boersma | Platelet glycoprotein IIb/IIIa inhibitors in acute coronary syndromes: a meta-analysis of all major randomised clinical trials[END_REF]. However, the fact that inflammatory pro-thrombotic environment in ACS leading to cardiac arrest was significantly different than in others has been recently pointed at. Empana et al showed higher concentrations of endothelial-derived micro particles in sudden cardiac death due to acute coronary occlusion compared with acute myocardial infarction with STEMI without rhythmic disturbances suggesting different patterns of acute coronary occlusion [START_REF] Empana | Microparticles and sudden cardiac death due to coronary occlusion. The TIDE (Thrombus and Inflammation in sudden DEath) study[END_REF]. Nevertheless, a more recent study analyzed the thrombus with a quantitative method using scanning electron microscopy did not find any differences of composition between intra-coronary thrombi of patients presenting with STEMI leading to sudden cardiac death or not [START_REF] Silvain | Thrombus composition in sudden cardiac death from acute myocardial infarction[END_REF]. In this study time from symptom onset to coronary reperfusion seems to be the strongest factor influencing thrombus composition in myocardial infarction. Use of GPi showed empiric benefit concerning thrombotic events following PCI [START_REF] Ibanez | ESC Guidelines for the management of acute myocardial infarction in patients presenting with STsegment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC)[END_REF] though data lack in this in this specific context of ACS leading to cardiacarrest. In our study, we noted a numerically higher ST rate in the Gpi group. We believe that this was due to two main factors. First, the fact that patients in the Gpi group had higher thrombotic burden is of importance to note as these patients might be at greater risk of ST. Indeed, we cannot ascertain that patients with higher thrombus burden might not have benefited from GPi, as such therapy has been proven to reduce thrombus burden [START_REF] Capodanno | Intravenous antiplatelet therapies (glycoprotein IIb/IIIa receptor inhibitors and cangrelor) in percutaneous coronary intervention: from pharmacology to indications for clinical use[END_REF].

Nevertheless, recent analysis demonstrated low ischemic benefit on top of P2Y12 inhibitors [START_REF] Ibrahim | Glycoprotein IIb/IIIa inhibitor use in patients with acute myocardial infarction undergoing PCI: Insights from the TRANSLATE ACS study[END_REF][START_REF] Tavenier | Efficacy and Safety of Glycoprotein IIb/IIIa Inhibitors on Top of Ticagrelor in STEMI: A Subanalysis of the ATLANTIC Trial[END_REF]. If routine Gpi use should not be advised in OHCA patients, randomized controlled studies with Gpi, cangrelor and oral P2Y12 inhibitors could be of interest in such patients.

Second, the fact that Gpi patients experienced more major bleedings could result in a need to interrupt other antithrombotic therapies and result in ST. Indeed, in stable patients who experienced both bleeding and ischemic events, bleeding events were reported to occur first in most patients [START_REF] Ducrocq | Balancing the risk of spontaneous ischemic and major bleeding events in acute coronary syndromes[END_REF].

Our study showed an increased risk of bleeding events (any events, p=0.002 and BARC 3 or 5 events, p=0.007) in the GPi groups without any increased of ST or in-hospital death (p=0.10 and p=0.68, respectively). These results are consistent with precedent data. In a single center observational study, Jimenez-Britez et al. showed that the incidence of any bleeding (64.7% vs. 14.8%, p<0.0001) and major bleeding (41.1% vs. 3.7%, p<0.0001) was significantly higher in patients receiving GPi. Their definition of thrombotic events contained ST but also deep vein thrombosis and pulmonary thrombosis and there were no significant differences between the two groups (p=0.76). In-hospital mortality was not significantly different either (24% vs. 35.2%, p=0.39) [START_REF] Jiménez-Brítez | Safety of glycoprotein IIb/IIIa inhibitors in patients under therapeutic hypothermia admitted for an acute coronary syndrome[END_REF]. To our knowledge, our study is the largest reported, demonstrating that GPi could increase bleeding events without any difference on in-hospital or stent thrombosis. Interestingly, even if not statistically relevant, stent thrombosis was numerically higher in GPi use. In the 19 patients with GPi who presented ST, 6 also presented a major bleeding complication according to BARC criteria (31.6%). In these cases, an early discontinuation of the double antiplatelet therapy may have led to an increased risk of ST which would have been related to GPi use in the first place. The hypothesis would need further investigation with more important cohorts of OHCA patients presenting with ACS.

In the population of OHCA patients with ACS, cardiogenic shock as well as reduced body temperature impacts platelet reactivity. In a prospective observational non-randomized study including 25 resuscitated patients, lowest inhibitory effects of both aspirin and P2Y12 inhibitors was shown on day 3 [START_REF] Prüller | Impaired aspirin-mediated platelet function inhibition in resuscitated patients with acute myocardial infarction treated with therapeutic hypothermia: a prospective, observational, non-randomized single-centre study[END_REF]. The authors emphasized that intravenous aspirin and P2Y12 inhibitors might supply a more predictable and stable platelet inhibition. However, in another study comparing the effects of clopidogrel and GPi on platelet reactivity in patients resuscitated from OHCA and undergoing PCI and hypothermia, the antiplatelet effect of clopidogrel measured by VerifyNow was significantly lower in the post-cardiac arrest group, close to zero with an increase to only around 10% after 48 hours. In the other hand, patients receiving GPi showed profound platelet inhibition measured by both VerifyNow IIb/IIIa and Multiplate TRAP tests for at least 22 hours after administration. These results showed that Clopidogrel loading does not significantly affect platelet function during the first 48 hours. This is in contrast with eptifibatide which produces profound platelet inhibition, and may be used to bridge insufficient inhibition by clopidogrel [START_REF] Steblovnik | Platelet reactivity in comatose survivors of cardiac arrest undergoing percutaneous coronary intervention and hypothermia[END_REF]. Nevertheless, a new P2Y12 inhibitor has been recently be added to the arsenal in patient presenting for ACS in a cardiacarrest context. Indeed, cangrelor belongs to a novel chemical class, cyclopentyl triazolopyrimidine, and is a direct, reversibly binding P2Y12 inhibitor with a plasma half-life of 12 h. It has been shown to provide effective platelet inhibition and is an appealing alternative to GPi in this context [START_REF] Qamar | Current status of data on cangrelor[END_REF]. Its efficacy has been assessed in three randomized controlled trials enrolling patients with PCI for stable angina or ACS against clopidogrel loading or placebo [START_REF] Qamar | Current status of data on cangrelor[END_REF]. However, the comparative efficacy and safety of routine early oral P2Y12 inhibitor administration vs. the use of cangrelor in the catheterization laboratory in patients with ACS undergoing invasive management deserves further investigation.

Nevertheless, OHCA patients in shock and treated with hypothermia therapy remains a specific population with different inflammatory pro-thrombotic environment and the standardized medication could be less effective. Further studies are warranted to confirm the mechanisms of higher thrombotic events, as well as to assess the appropriate management of these patients. In addition, inadequate platelet inhibition is only one component of ST pathogenesis as an individual's susceptibility to ST is multifactorial involving clinical factors, endothelial biology, inflammatory reaction, blood rheology, platelet reactivity, clotting factors, physical and mechanical properties of the stent [START_REF] Gori | Predictors of stent thrombosis and their implications for clinical practice[END_REF]. Therefore all efforts should be done to reduce any potential ST trigger, such as appropriate stenting technique, with the help, if needed of intravascular imaging; inflammatory reaction control and other manageable factors such as hyperglycemia or hypoperfusion.

The present study has several limitations that need to be acknowledged. The results must be interpreted with caution, as this is a single-center non-randomized study with a relatively small sample size. Thus, the differences in baseline or procedural characteristics might have impacted on the final results of the study. Nevertheless, to our knowledge, our study is the largest analyzing the safety of GPi in OHCA patients. Among them, the higher thrombotic burden in the patients receiving GPi might probably reflect a more pro-thrombotic environment that could lead to an increased risk of stent thrombosis. Nonetheless, these limitations may potentially impact on thrombotic but not hemorrhagic events. The study included patients that were treated over a long period (10 years). Indeed, the use of clopidogrel was superior between 2007 and 2012; conversely ticagrelor and prasugrel were more used after 2012. In addition, mechanical support devices such as IABP and Impella were more often used in the first 5 years of the study, due to in-hospital management protocols.

However there were no difference in mortality between these two periods (2007-2012: 45.1% ; 2013-2017 : 41.9%; p=0.27). In addition, although therapeutic hypothermia was performed in the vast majority of the patients, the depth of hypothermia was not recorded.

The choice of the P2Y12 inhibitor and GPi use was not randomized and left to the discretion of the clinician, therefore introducing potential bias. In addition, type, dose, and duration of GPi are not detailed in the present analysis, which can hamper detailed analysis of GPi administration. Also, there was an evolution in stent thrombosis rates during the study period with the use of bare metal stents; first, second and third generation of drug-eluting stents, as well as an evolution in the access site (ie, radial vs femoral) which were not recorded in the present analysis. Due to high mortality rate, ST might have been missed in a number of patients. Nevertheless, repeated coronary angiography was usually performed in the department in case of recurrent ST-segment elevation, abnormal troponin rise after the acute phase or hemodynamic degradation associated with ECG modifications, factors usually associated with ST. In addition, ST rates should have affected both groups and might not be in favor of one group or the other. Finally, the rates of any bleeding might have been underreported as they are rarely mentioned in medical charts.

Conclusion

In this study, the use of GPi in patients with ACS in a context of OHCA was associated with an increased risk of any bleeding or major bleeding events according to BARC criteria, without any significant differences concerning the risk of stent thrombosis or in-hospital death. Further studies are required to insure the safety of GPi in the very specific population of patient undergoing PCI following a cardiac arrest.

Figure 1 :

 1 Figure 1: Study Flowchart. Abbreviations: CCU: critical care unit; OHCA: out of hospital

Figure 2 :Supplementary Figure 1 :

 21 Figure 2: Outcomes according to GPi use. ST=stent thrombosis; GPi=Glycoprotein IIb/IIIa

Table 1 :

 1 Baseline characteristics, clinical presentation and pre-hospital management.

	Tables
	Abbreviations: BMI: Body mass index, PCI: Percutaneous coronary intervention, EES:
	External electric shock; LVEF: left ventricular ejection fraction
		GPi (n : 159)	Non GPi (n : 226)	p value
	Age, years, mean ± SD	57.8 ± 12.4	62.9 ± 12.1	0.23
	Male, no. (%)	126 (79.2%)	169 (74.8%)	0.31
	BMI, mean ± SD	133 (26.0 ± 4.1)	26.7 ± 5.0	0.70
	Smoking, no. (%)	105 (66.0%)	142 (62.8%)	0.52
	Hypertension, no. (%)	42 (26.4%)	110 (48.7%)	<0.001
	Diabetes mellitus, no. (%)	20 (12.6%)	44 (19.5%)	0.07
	Hypercholesterolemia, no. (%)	37 (23.3%)	72 (31.9%)	0.07
	Family history of coronary artery disease, no. (%)	8 (5.0%)	19 (8.4%)	0.20
	Previous PCI, no. (%)	15 (9.4%)	56 (24.9%)	<0.001
	Anticoagulant treatment, no. (%)	8 (5.0%)	12 (5.3%)	0.90
	Initial shockable rhythm, no. (%)	138 (87.3%)	172 (76.8%)	0.01
	Present witness, no. (%)	154 (97.5%)	217 (96.0%)	0.44
	Rescucitation by the witness, no. (%)	107 (68.2%)	143 (63.6%)	0.35
	No Flow time, min, Median (IR)	2 (0 -5)	2 (0 -7)	0.29
	Low Flow time, min, Median (IR)	15 (10 -28)	20 (10 -25)	0.14
	Mechanical ventilation	156 (98.1%)	221 (97.8%)	0.99
	Therapeutic hypothermia	135 (84.9%)	196 (86.7%)	0.61
	ST-segment elevation myocardial infarction, no. (%)	132 (83.0%)	146 (64.6%)	<0.001
	Number of EES, mean ± SD	1.1 ± 1.4	1.0 ± 1.7	0.10
	Adrenaline injection, no. (%)	86 (54.4%)	120 (54.1%)	0.94
	Morphine injection, no. (%)	158 (99.4%)	224 (99.1%)	0.78
	LVEF, %, mean ± SD	36.4 ± 14.1	36.8 ± 14.7	0.81

Table 2 :

 2 Procedural characteristics. Abbreviations: IABP: intra-aortic balloon pump, ECMO:

	extra-corporeal mechanical oxygenation, TIMI: thrombolysis in myocardial infarction, PCI:
	percutaneous coronary intervention, LAD: left descending artery, LCX: left circumflex artery,
	RCA: Right coronary artery.
		GPi (n: 159)	Non GPi (n: 226) p value
	Antiplatelets administered before or during catheterization
	procedure, no. (%)
	Aspririne + Clopidogrel	78 (49.1%)	114 (50.4%)	0.79
	Aspirine + Ticagrelor or Prasugrel	70 (44.0%)	91 (40.3%)	0.46
	IABP, no. (%)	43 (27.0%)	41 (18.1%)	0.04
	Impella implantation, no. (%)	10 (6.3%)	11 (4.9%)	0.55
	ECMO implantation, no. (%)	8 (5.2%)	13 (5.8%)	0.78
	Thromboaspiration, no. (%)	101 (63.9%)	65 (28.9%)	<0.0001
	TIMI flow 0 or 1 before PCI, no. (%)	127 (79.9%)	131 (58.0%)	<0.0001
	TIMI flow 3 after PCI, no. (%)	148 (93.1%)	218 (96.5%)	0.13
	Bifurcation lesion, no. (%)	39 (24.5%)	61 (26.9%)	0.63
	Culprit coronary artery, no. (%)
	LAD	103 (64.7%)	120 (53.1%)	0.02
	LCX	24 (15.1%)	47 (20.8%)	0.16
	RCA	31 (19.5%)	57 (26.1%)	0.19
	Other	1 (0.6%)	2 (0.9%)	0.78
	No reflow, no. (%)	14 (8.9%)	4 (1.8%)	0.001
	Total length of implanted stent, mm, mean ± (SD)	26.6 ± 13.8	30.7 ± 21.1	0.04
	Switch of antiplatelets, no. (%)	24 (15.1%)	52 (23.0%)	0.06

Table 3 :

 3 Uni and multivariate analysis of factors associated with the use of Gpi. Abbreviations: Same as Table1 and 2.

	Univariate predictors	Odds ratio	95% CI	p value
	Age, years, mean ± SD	0.97	0.95-0.98	<0.0001
	Male, no. (%)	1.3	0.79-2.10	0.31
	BMI, mean ± SD	0.97	0.92-1.02	0.22
	Anticoagulant treatment, no. (%)	0.94	0.38-2.36	0.90
	Initial shockable rhythm, no. (%)	2.09	1.19-3.66	0.01
	IABP use, no. (%)	1.67	1.03-2.72	0.04
	Impella implantation, no. (%)	1.31	0.54-3.17	0.55
	ECMO implantation, no. (%)	0.88	0.36-2.17	0.78
	Thromboaspiration, no. (%)	4.36	2.83-6.73	<0.0001
	TIMI flow 0 or 1 before PCI, no. (%)	2.88	1.80-4.60	<0.0001
	TIMI flow 3 after PCI, no. (%)	0.79	0.58-1.08	0.14
	Bifurcation lesion, no. (%)	0.89	0.57-1.40	0.63
	No reflow, no. (%)	5.40	1.74-16.72	0.003
	Total length of implanted stent, mm, mean ± (SD)	0.99	0.98-1.00	0.04
	Therapeutic hypothermia	0.86	0.48-1.54	0.61
	Multivariate predictors	Odds ratio	95% CI	p value
	Age, years, mean ± SD	0.98	0.96-1.00	0.04
	Previous PCI, no. (%)	0.49	0.25-0.96	0.04
	Initial shockable rhythm, no. (%)	1.20	0.63-2.30	0.58
	IABP use, no. (%)	1.20	0.69-2.08	0.53
	Thromboaspiration, no. (%)	2.89	1.78-4.70	<0.0001
	TIMI flow 0 or 1 before PCI, no. (%)	2.01	1.17-3.45	0.01
	TIMI flow 3 after PCI, no. (%)	1.13	0.70-1.83	0.62
	No reflow, no. (%)	3.78	0.81-17.62	0.09
	Total length of implanted stent, mm, mean ± (SD)	0.99	0.98-1.01	0.25

Table 4 :

 4 Clinical outcomes. Abbreviation: BARC: Bleeding Academic Research Consortium

	GPi (n: 159)	Non GPi (n: 226)	p value

Table 5 :

 5 Uni-and multivariate analysis of factors associated with major (BARC 3-5) bleedings. Abbreviations: Same as Table1,2 and 4.

	Univariate predictors	Odds ratio	95% CI	p value
	BMI, mean ± SD	0.96	0.90-1.03	0.26
	Smoking, no. (%)	0.76	0.46-1.25	0.27
	Antiplatelets administered before or during catheterization
	procedure, no. (%)
	Aspririne + Clopidogrel	0.72	0.44-1.17	0.18
	Aspirine + Ticagrelor or Prasugrel	1.48	0.91-2.41	0.12
	GpIIbIIIa inhibitors use, no. (%)	1.95	1.20-3.19	0.007
	Thromboaspiration, no. (%)	1.45	0.90-2.37	0.13
	Total length of implanted stent, mm, mean ± (SD)	0.99	0.97-1.00	0.10
	Switch of antiplatelets, no. (%)	1.28	0.71-2.30	0.42
	Therapeutic hypothermia	0.85	0.43-1.67	0.63
	Anticoagulation use	0.90	0.29-2.77	0.86
	No-Flow duration	0.97	0.91-1.02	0.23
	Low-Flow duration	1.01	1.00-1.03	0.08
	Mechanical support device (ECMO, Impella or IABP)	1.86	1.12-3.10	0.02
	Multivariate predictors	Odds ratio	95% CI	p value
	Aspirine + Ticagrelor or Prasugrel, no. (%)	1.99	1.15-3.46	0.01
	GpIIbIIIa inhibitors use, no. (%)	1.81	1.06-3.08	0.03
	Thromboaspiration, no. (%)	1.15	0.66-2.01	0.61
	Total length of implanted stent, mm, mean ± (SD)	0.99	0.97-1.00	0.12
	Low-Flow duration	1.01	1.00-1.03	0.07
	Mechanical support device (ECMO, Impella or IABP)	2.03	1.14-3.62	0.02