Fibrolamellar Carcinoma: What Is New and Why It Matters

How Do I Diagnose Fibrolamellar Carcinoma?

Fibrolamellar carcinoma (FLC) is a unique primary carcinoma of the liver that is characterized by distinct morphologic findings and a recurrent DNAJB1::PRKACA gene fusion. It typically presents in young individuals without underlying liver dysfunction. FLC is difficult to diagnose when based only on morphology, and misdiagnosis is common. Frequent differential diagnoses include conventional hepatocellular carcinoma and intrahepatic cholangiocarcinoma, both of which can show similar morphologic and immunohistochemical features. If based only on molecular analysis, other differential diagnoses have recently emerged, as the DNAJB1::PRKACA fusion has now been reported in cases of intraductal oncocytic papillary neoplasm and intraductal papillary mucinous neoplasm. In this article, we review our diagnostic approach to FLC, which relies on both morphologic and immunohistochemical features, as well as molecular analysis.

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

CONTEXT

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

OBJECTIVE

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

DATA SOURCES

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

CONCLUSIONS

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

Update on the Pathology of Pediatric Liver Tumors: A Pictorial Review

Liver tumors in children are uncommon and show remarkable morphologic heterogeneity. Pediatric tumors may arise from either the epithelial or mesenchymal component of the liver and rarely may also show both lines of differentiation. Both benign and malignant liver tumors have been reported in children. The most common pediatric liver tumors by age are benign hepatic infantile hemangiomas in neonates and infants, malignant hepatoblastoma in infants and toddlers, and malignant hepatocellular carcinoma in teenagers. Here, we provide an up-to-date review of pediatric liver tumors. We discuss the clinical presentation, imaging findings, pathology, and relevant molecular features that can help in the correct identification of these tumors, which is important in managing these children.

Clinical Outcomes in Fibrolamellar Hepatocellular Carcinoma Treated with Immune Checkpoint Inhibitors

BACKGROUND

Fibrolamellar hepatocellular carcinoma (FLC) is a rare form of liver cancer primarily affecting children and young adults. Although considered a subset of hepatocellular carcinoma (HCC), FLC has unique molecular and pathologic characteristics, suggesting that it may require different treatment. Immune checkpoint inhibitors (ICIs) are used in the treatment of HCC, but efficacy and safety in FLC has not been characterized.

METHODS

We performed a multicenter retrospective analysis of patients with FLC to determine responses to ICI therapy. Response rates were assessed based on RECIST 1.1 criteria, and Kaplan-Meier statistics were used for progression-free survival (PFS) and overall survival (OS).

RESULTS

FLC tumors were characterized by low tumor mutational burden (TMB) and absent PD-L1 expression. We identified 19 patients who received ICIs, including 15 who received ICI therapy alone [programmed death receptor 1 (PD-1) inhibitor, +/- cytotoxic T lymphocyte antigen-4 (CTLA-4) inhibitor]. Objective tumor responses were observed in 3/19 patients (15.8%), including 2/15 patients (13.3%) who received ICIs alone, all partial responses. Median PFS and OS were 5.5 and 26.0 months, respectively. Grade 3-4 immune related adverse events were observed in 4/19 (21.1%) patients.

CONCLUSIONS

ICI therapy has modest clinical activity in FLC, and novel therapeutic combinations are needed.

Refractory Hyperammonemic encephalopathy in Fibrolamellar hepatocellular carcinoma, a case report and literature review

Fibrolamellar hepatocellular carcinoma is a rare type of hepatocellular carcinoma with unclear etiology. Its prevalence ranges from 0.6%-5%. One of the rare manifestations of FHCC includes hyperammonemic hepatic encephalopathy (HAE). Data regarding HAE in FHCC is limited to case reports, and much is unknown, including its precipitating factors, clinical course, and management. We have reported one such case of FHCC associated HAE and presented an extensive literature review on the topic. We report the case of a 26-year-old Pakistani male who was diagnosed with fibrolamellar hepatocellular carcinoma. On day five after the first chemotherapy, he presented with nausea, vomiting, and confusion. His serum ammonia level was raised, and he was treated with lactulose and rifaximin. The patient continued chemotherapy and had recurrent admissions with HAE. A detailed workup revealed acquired ornithine transcarbamylase deficiency. Ammonia level peaked at 694 umol/L during the clinical course of his disease. He received treatment with multiple ammonia scavengers, including sodium benzoate + phenylacetate, with relief of symptoms and reduction in ammonia level. The patient was eventually lost to follow-up. HAE presents as a paraneoplastic manifestation of FHCC. Patients have laboratory features suggestive of acquired ornithine transcarbamylase deficiency. There is a variable frequency of episodes reported in the literature. Most patients respond well to ammonia scavenger therapies rather than conventional HE management with lactulose or rifaxmin.

A framework for fibrolamellar carcinoma research and clinical trials

Fibrolamellar carcinoma (FLC), a rare, lethal hepatic cancer, occurs primarily in adolescents and young adults. Unlike hepatocellular carcinoma, FLC has no known association with viral, metabolic or chemical agents that cause cirrhosis. Currently, surgical resection is the only treatment demonstrated to achieve cure, and no standard of care exists for systemic therapy. Progress in FLC research illuminates a transition from an obscure cancer to one for which an interactive community seems poised to uncover fundamental mechanisms and initiate translation towards novel therapies. In this Roadmap, we review advances since the seminal discovery in 2014 that nearly all FLC tumours express a signature oncogene (DNAJB1-PRKACA) encoding a fusion protein (DNAJ-PKAc) in which the J-domain of a heat shock protein 40 (HSP40) co-chaperone replaces an amino-terminal segment of the catalytic subunit of the cyclic AMP-dependent protein kinase (PKA). Important gains include increased understanding of oncogenic pathways driven by DNAJ-PKAc; identification of potential therapeutic targets; development of research models; elucidation of immune mechanisms with potential for the development of immunotherapies; and completion of the first multicentre clinical trials of targeted therapy for FLC. In each of these key areas we propose a Roadmap for future progress.

Gene Fusions in Gastrointestinal Tract cancers

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

DNAJB1-PRKACA in HEK293T cells induces LINC00473 overexpression that depends on PKA signaling

Fibrolamellar carcinoma (FLC) is a primary liver cancer that most commonly arises in adolescents and young adults in a background of normal liver tissue and has a poor prognosis due to lack of effective chemotherapeutic agents. The DNAJB1-PRKACA gene fusion (DP) has been reported in the majority of FLC tumors; however, its oncogenic mechanisms remain unclear. Given the paucity of cellular models, in particular FLC tumor cell lines, we hypothesized that engineering the DP fusion gene in HEK293T cells would provide insight into the cellular effects of the fusion gene. We used CRISPR/Cas9 to engineer HEK293T clones expressing DP fusion gene (HEK-DP) and performed transcriptomic, proteomic, and mitochondrial studies to characterize this cellular model. Proteomic analysis of DP interacting partners identified mitochondrial proteins as well as proteins in other subcellular compartments. HEK-DP cells demonstrated significantly elevated mitochondrial fission, which suggests a role for DP in altering mitochondrial dynamics. Transcriptomic analysis of HEK-DP cells revealed a significant increase in LINC00473 expression, similar to what has been observed in primary FLC samples. LINC00473 overexpression was reversible with siRNA targeting of PRKACA as well as pharmacologic targeting of PKA and Hsp40 in HEK-DP cells. Therefore, our model suggests that LINC00473 is a candidate marker for DP activity.

Focal hepatic intrinsically hyperattenuating lesions at unenhanced CT: Not always calcifications

Due to the growing use of CT, there has been an increase in the frequency of detecting focal liver lesions. Intrinsically hyperattenuating hepatic lesions or pseudolesions are not uncommon at unenhanced CT. Hyperattenuating hepatic lesions can be divided into non-calcified and calcified. Causes of intrinsic hyperattenuation include hemorrhage, thrombosis, and calcifications. Focal liver lesions can show hyperattenuation on unenhanced CT in case of severe liver steatosis. Recognition of etiologies associated with hyperattenuation on unenhanced CT can help the radiologist in characterizing focal liver lesions and pseudolesions. In this paper, we describe the spectrum of intrinsically hyperattenuating focal liver lesions and pseudolesions at unenhanced CT.

Rare variants of primary liver cancer: Fibrolamellar, combined, and sarcomatoid hepatocellular carcinomas

Hepatocellular carcinoma (HCC) constitutes 80% of all primary liver cancers. Based on key developments in the understanding of its carcinogenesis and the advancement of treatment options, detailed algorithms and practice guidelines have been published to guide the clinical management of HCC. Furthermore, several subclasses of HCC have been described based on molecular profiles and linked to pathological characteristics, clinical features, and disease aggressiveness. Most recently, the combination of the checkpoint inhibitor atezolizumab plus bevacizumab has significantly increased treatment response in the first line systemic treatment of HCC. Unfortunately, rare HCC variants, in particular fibrolamellar liver cancer (FLC), combined hepatocellular carcinoma and cholangiocarcinoma (cHCC-CCA), and sarcomatoid hepatocellular carcinoma (sHCC), were excluded from phase III studies. Therefore, data for decision-making and treatment allocation for these distinct entities, representing 1-5% of all primary liver cancers, is scarce. Moreover, most of the knowledge available for these rare HCC variants is based on registry data and retrospective studies. In this position paper, we briefly summarize the current clinical knowledge regarding FLC, cHCC-CCA, and sHCC. Based on our summary, we propose future clinical research activities within the framework of the European Reference Network on Hepatological Diseases (ERN RARE-LIVER).

Imaging Features of Fibrolamellar Hepatocellular Carcinoma with Contrast-Enhanced Ultrasound

PURPOSE

 Fibrolamellar hepatocellular carcinoma (f-HCC) is a rare primary liver tumor. Imaging plays an important role in diagnosis. The aim of this retrospective study was to analyze contrast-enhanced ultrasound (CEUS) features of histologically proven f-HCC in comparison to benign focal nodular hyperplasia (FNH).

MATERIALS & METHODS

 16 patients with histologically proven f-HCC lesions and 30 patients with FNH lesions were retrospectively reviewed regarding CEUS features to determine the malignant or benign nature of the focal liver lesions (FLL). Five radiologists assessed the CEUS enhancement pattern and came to a consensus using the EFSUMB (European Federation of Societies for Ultrasound in Medicine and Biology) guideline criteria.

RESULTS

 Fibrolamellar hepatocellular carcinoma manifested as a single and huge FLL. On CEUS, f-HCC showed heterogeneous hyperenhancement in the arterial phase and hypoenhancement (16/16, 100 %) in the portal venous and late phases (PVLP) as a sign of malignancy. In contrast to the hypoenhancement of f-HCC in the PVLP, all patients with FNH showed hyperenhancement as the most distinctive feature (P < 0.01). 8 f-HCC lesions showed a central scar as an unenhanced area (8/16, 50.0 %), which could also be detected in 53.3 % (16/30) of FNH lesions (P > 0.05).

CONCLUSION

 By analyzing the hypoenhancement in the PVLP, CEUS imaging reliably diagnosed f-HCC as a malignant FLL. CEUS also showed differentiation between f-HCC and FNH lesions, showing similar non-enhanced central scars, whereas f-HCC lesions showed peripheral hyperenhancement in the arterial phase and early washout in the PVLP.

Stay on Target: Reengaging Cancer Vaccines in Combination Immunotherapy

Effective treatment of established tumors requires rational multicombination immunotherapy strategies designed to target all functions of the patient immune system and tumor immune microenvironment. While these combinations build on the foundation of successful immune checkpoint blockade antibodies, it is increasingly apparent that successful immunotherapy will also require a cancer vaccine backbone to engage the immune system, thereby ensuring that additional immuno-oncology agents will engage a tumor-specific immune response. This review summarizes ongoing clinical trials built upon the backbone of cancer vaccines and focusing on those clinical trials that utilize multicombination (3+) immuno-oncology agents. We examine combining cancer vaccines with multiple checkpoint blockade antibodies, novel multifunctional molecules, adoptive cell therapy and immune system agonists. These combinations and those yet to enter the clinic represent the future of cancer immunotherapy. With a cancer vaccine backbone, we are confident that current and coming generations of rationally designed multicombination immunotherapy can result in effective therapy of established tumors.

Pathologic and molecular features of hepatocellular carcinoma: An update

Morphological diversity and several new distinct pathologic subtypes of hepatocellular carcinoma (HCC) are now well-recognized. Recent advances in tumor genomics and transcriptomics have identified several recurrent somatic/genetic alterations that are closely related with histomorphological subtypes and have therefore, greatly improved our understanding of HCC pathogenesis. Pathologic subtyping allows for a diagnosis which is clinically helpful and can have important implication in patient prognostication as some of these subtypes are extremely aggressive with vascular invasion, early recurrence, and worst outcomes. Several targeted treatments are now being considered in HCC, and the reporting of subtypes may be quite useful for personalized therapeutic purpose. This manuscript reviews the recently identified histomorphological subtypes and molecular alterations in HCC.

Early Experiences with Triple Immunochemotherapy in Adolescents and Young Adults with High-Risk Fibrolamellar Carcinoma

INTRODUCTION

There are no standard systemic therapies for the treatment of fibrolamellar carcinoma (FLC), as surgery remains the only definitive option. We share our experiences using systemic "triple therapy" (TT) with 5-fluorouracil, interferon, and nivolumab for the treatment of relapsed, refractory, metastatic, or unresectable FLC.

METHODS

Data from all patients who received TT from May 2018 to July 2020 were reviewed to assess response, survival, and toxicity.

RESULTS

A total of 22 patients were treated with TT, of which 14 (median age of 21 years) were evaluable. They received a median of 18 cycles (8-44). At the time of analysis, the median progression-free survival was 9 months (4.5-26), 29% longer than prior to TT, with 5 patients achieving clinical remission, 8 patients stable or improving, and 1 progression. Overall objective response (clinical remission + partial response) was 50% and tumor control rate (clinical remission + partial response + stable disease) was 93%. Two patients withdrew from treatment due to side effects.

DISCUSSION/CONCLUSION

Our early results support TT as a promising medical option to slow disease progression and prolong survival in high-risk patients with FLC. TT can be administered in the outpatient setting and has shown good tolerability. Further longitudinal data is needed to confirm outcomes, especially in patients still early in their treatment.

An update on subtypes of hepatocellular carcinoma: From morphology to molecular

The morphologic spectrum of hepatocellular carcinoma (HCC) is quite broad. While in about one-third of cases, the neoplasms can be categorized into meaningful subtypes based on morphology, a vast majority of these neoplasms are morphologically heterogeneous. With extensive tumor profiling, data has begun to emerge which can correlate specific morphologic features with underlying molecular signatures. A true morphologic subtype not only has reproducible H & E features, further supported by specific immunohistochemical or molecular signatures, but also has specific clinical implications and prognostic associations. Eight such morphologic subtypes are recognized by the 2019 WHO classification of tumors with a few more additional subtypes described in the literature. The goal of this review is to familiarize the reader with the morphologic subtypes and elaborate on the clinical and molecular associations of these neoplasms.

Fibrolamellar carcinoma: Challenging the challenge

Fibrolamellar carcinoma (FLC) is a rare and poorly understood malignancy, which seems to be more prevalent in young patients compared with conventional hepatocellular carcinoma (HCC). Performing prospective clinical trials recruiting patients diagnosed with FLC has proven challenging with scarce data available guiding clinical management. The use of a number of chemotherapy compounds in these patients, including cisplatin, epirubicin, 5-fluorouracil (5-FU) and recombinant interferon α-2B (IFN-α-2B), has been reported in the literature, mainly in the form of case reports. The most promising systemic therapy tested so far is the combination of 5-FU infusion and 3-weekly IFN-α-2B, based on results from a phase II clinical trial. This article provides an overview of our own experience with this treatment schedule for patients with FLC, confirming its activity and treatment-derived benefit in the real world. Current challenges being faced by healthcare professionals treating patients with advanced FLC are discussed, especially the increasingly limited access to IFN-α-2B, which could compromise the access to an active therapy in the coming future, and the difficulties in the development of new treatment options for advanced FLC.

DNAJB1-PRKACA fusions occur in oncocytic pancreatic and biliary neoplasms and are not specific for fibrolamellar hepatocellular carcinoma

Recently discovered DNAJB1-PRKACA oncogenic fusions have been considered diagnostic for fibrolamellar hepatocellular carcinoma. In this study, we describe six pancreatobiliary neoplasms with PRKACA fusions, five of which harbor the DNAJB1-PRKACA fusion. All neoplasms were subjected to a hybridization capture-based next-generation sequencing assay (MSK-IMPACT), which enables the identification of sequence mutations, copy number alterations, and selected structural rearrangements involving ≥410 genes (n = 6) and/or to a custom targeted, RNA-based panel (MSK-Fusion) that utilizes Archer Anchored Multiplex PCR technology and next-generation sequencing to detect gene fusions in 62 genes (n = 2). Selected neoplasms also underwent FISH analysis, albumin mRNA in-situ hybridization, and arginase-1 immunohistochemical labeling (n = 3). Five neoplasms were pancreatic, and one arose in the intrahepatic bile ducts. All revealed at least focal oncocytic morphology: three cases were diagnosed as intraductal oncocytic papillary neoplasms, and three as intraductal papillary mucinous neoplasms with mixed oncocytic and pancreatobiliary or gastric features. Four cases had an invasive carcinoma component composed of oncocytic cells. Five cases revealed DNAJB1-PRKACA fusions and one revealed an ATP1B1-PRKACA fusion. None of the cases tested were positive for albumin or arginase-1. Our data prove that DNAJB1-PRKACA fusion is neither exclusive nor diagnostic for fibrolamellar hepatocellular carcinoma, and caution should be exercised in diagnosing liver tumors with DNAJB1-PRKACA fusions as fibrolamellar hepatocellular carcinoma, particularly if a pancreatic lesion is present. Moreover, considering DNAJB1-PRKACA fusions lead to upregulated protein kinase activity and that this upregulated protein kinase activity has a significant role in tumorigenesis of fibrolamellar hepatocellular carcinoma, protein kinase inhibition could have therapeutic potential in the treatment of these pancreatobiliary neoplasms as well, once a suitable drug is developed.

Phase II Multicenter, Open-Label Study of Oral ENMD-2076 for the Treatment of Patients with Advanced Fibrolamellar Carcinoma

LESSONS LEARNED

The fibrolamellar carcinoma-associated DNAJB1-PRKACA gene fusion transcript RNA codes for the catalytic domain of protein kinase A and, thus, overexpression of Aurora kinase A. ENMD-2076 showed a favorable toxicity profile. The limited results, one patient (3%) with a partial response and 57% of patients with stable disease, do not support further evaluation of ENMD-2076 as single agent. Future studies will depend on the simultaneous targeting approach of DNAJB1-PRKACA and the critical downstream components.

BACKGROUND

Fibrolamellar carcinoma (FLC) represents approximately 0.85% of liver cancers. The associated DNAJB1-PRKACA gene fusion transcript RNA codes for the catalytic domain of protein kinase A and overexpression of Aurora kinase A (AURKA). ENMD-2076 is a selective anti-AURKA inhibitor.

METHODS

Patients aged >12 years with pathologically confirmed incurable FLC, with measurable disease, Eastern Cooperative Oncology Group performance status 0-2 or Lansky 70-100, and adequate organ function were eligible. Patients were prescribed ENMD-2076 based on body surface area. The primary endpoint was overall objective response rate by RECIST v1.1, with a null hypothesis of true response rate of 2% versus one-sided alternative of 15%. Secondary endpoints included 6-month progression-free survival (PFS) rate (Fig. 1), median PFS, time to progression (TTP), and overall survival (OS). Safety was evaluated throughout the study.

RESULTS

Of 35 patients who enrolled and received treatment, 1 (3%) had a partial response (PR) and 20 (57%) had stable disease (SD). Median TTP, PFS, and OS were 5, 3.9, and 19 months, respectively. The most frequently reported drug-related serious adverse event was hypertension in three patients. Three deaths were reported on-study-two due to disease progression and one due to pulmonary embolism not related to ENMD-2076.

CONCLUSION

The study provided no rationale for further studying ENMD-2076 as a single agent in FLC.

Deleted in Liver Cancer 2 (DLC2) protein expression in hepatocellular carcinoma

Deleted in Liver Cancer (DLC) proteins belong to the family of RhoGAPs and are believed to operate as negative regulators of the Rho family of small GTPases. So far, the role of the first identified member from the DLC family, DLC1, was established as a tumor suppressor in hepatocellular carcinoma. The function of its close family relative, DLC2 is unequivocal. In the present study we attempted to determine whether the loss of DLC2 is a common feature of hepatocellular carcinoma tissue. We examined two types of hepatocellular carcinomatypical and fibrolamellar one. Our analysis revealed that DLC2 protein is not diminished in cancer tissue when compared to non-cancerous liver specimens. What is more, we observed DLC2 to be more abundantly expressed in cancer tissue, particularly in tumors with the inflammation background. In addition, we found that DLC2 gene status was diploid in virtually all tumor samples examined. Our results indicate that DLC2 is not diminished in hepatocellular carcinoma cells. It appears that members of the DLC family, although structurally highly related, may function differently in cancer cells.