Small cell undifferentiated variant of hepatoblastoma: adverse clinical and molecular features similar to rhabdoid tumors

Hepatoblastomas in Oman: Unveiling success

OBJECTIVES

Primary malignant liver tumours account for more than 1% of all paediatric malignancies, with the most common form being hepatoblastomas (HB). Such malignancies among Arab populations have rarely been addressed in the literature. Using data from Oman's sole national referral centre for childhood solid malignancies, this study aimed to present the nationwide Omani experience with HB over the past 21 years.

METHODS

This retrospective study reviewed the medical records of all children with HB who were managed in the Royal Hospital, Muscat, Oman, between January 1991 and April 2012. Clinical, radiological and laboratory characteristics were examined as well as treatments and outcomes.

RESULTS

During the study period, 15 patients with HB were treated. Of these, 10 have survived to date. Nine of the survivors were no longer receiving treatment and one patient still had the disease but was in a stable condition. Of the remaining five patients, three did not survive and two were lost to follow-up. The survival rate among patients who completed therapy was 91%.

CONCLUSION

HB has an excellent prognosis in Oman. The main obstacle to improving outcomes among Omani patients is non-compliance with therapy.

Effective strategy of the combination of high-intensity focused ultrasound and transarterial chemoembolization for improving outcome of unresectable and metastatic hepatoblastoma: a retrospective cohort study

The combination of high-intensity focused ultrasound (HIFU) and transarterial chemoembolization (TACE) has been experimentally performed in a variety of malignant tumors, and its validity has not yet been evaluated for hepatoblastoma (HB). We evaluated the disease-response rate, resection rate, and toxicity in children with unresectable or metastatic HB (stage III and stage IV HB) after sequential treatment with TACE plus HIFU in a controlled clinical trial. The 35 patients with unresectable or metastatic HB were nonrandomly assigned to HIFU ablation (n = 12) or C5V chemotherapy (n = 23). The rates of complete resection, tumor response, and treatment toxicity were evaluated for both regimens. Nine patients who received C5V and 10 patients who received TACE plus HIFU became operable (P = .02). The 3-year event-free survival and overall survival rates were 43.03% and 56.68% in the C5V group and 38.57% and 57.86% in the TACE plus HIFU group, respectively. Acute grade 3 or 4 adverse events, including neutropenia, thrombocytopenia, and anemia, were more frequent in patients treated with C5V therapy than in patients receiving TACE plus HIFU. HIFU ablation achieved a higher rate of complete resection and a lower rate of severe complications compared with C5V treatment in children with advanced HB (Chinese Clinical Trials Registry No. ChiCTR-PRCH-08000182).

SWI/SNF chromatin remodeling and human malignancies

The SWI/SNF complexes, initially identified in yeast 20 years ago, are a family of multi-subunit complexes that use the energy of adenosine triphosphate (ATP) hydrolysis to remodel nucleosomes. Chromatin remodeling processes mediated by the SWI/SNF complexes are critical to the modulation of gene expression across a variety of cellular processes, including stemness, differentiation, and proliferation. The first evidence of the involvement of these complexes in carcinogenesis was provided by the identification of biallelic, truncating mutations of the SMARCB1 gene in malignant rhabdoid tumors, a highly aggressive childhood cancer. Subsequently, genome-wide sequencing technologies have identified mutations in genes encoding different subunits of the SWI/SNF complexes in a large number of tumors. SWI/SNF mutations, and the subsequent abnormal function of SWI/SNF complexes, are among the most frequent gene alterations in cancer. The mechanisms by which perturbation of the SWI/SNF complexes promote oncogenesis are not fully elucidated; however, alterations of SWI/SNF genes obviously play a major part in cancer development, progression, and/or resistance to therapy.

Relapse surveillance in AFP-positive hepatoblastoma: re-evaluating the role of imaging

BACKGROUND

Children with hepatoblastoma routinely undergo repetitive surveillance imaging, with CT scans for several years after therapy, increasing the risk of radiation-induced cancer.

OBJECTIVE

The purpose of this study was to determine the utility of surveillance CT scans compared to serum alpha-fetoprotein (AFP) levels for the detection of hepatoblastoma relapse.

MATERIALS AND METHODS

This was a retrospective study of all children diagnosed with AFP-positive hepatoblastoma from 2001 to 2011 at a single institution.

RESULTS

Twenty-six children with hepatoblastoma were identified, with a mean age at diagnosis of 2 years 4 months (range 3 months to 11 years). Mean AFP level at diagnosis was 132,732 ng/ml (range 172.8-572,613 ng/ml). Five of the 26 children had hepatoblastoma relapse. A total of 105 imaging exams were performed following completion of therapy; 88 (84%) CT, 8 (8%) MRI, 5 (5%) US and 4 (4%) FDG PET/CT exams. A total of 288 alpha-fetoprotein levels were drawn, with a mean of 11 per child. The AFP level was elevated in all recurrences and no relapses were detected by imaging before AFP elevation. Two false-positive AFP levels and 15 false-positive imaging exams were detected. AFP elevation was found to be significantly more specific than PET/CT and CT imaging at detecting relapse.

CONCLUSION

We recommend using serial serum AFP levels as the preferred method of surveillance in children with AFP-positive hepatoblastoma, reserving imaging for the early postoperative period, for children at high risk of relapse, and for determination of the anatomical site of clinically suspected recurrence. Given the small size of this preliminary study, validation in a larger patient population is warranted.

Pediatric hepatoblastoma: diagnosis and treatment

Hepatoblastoma (HBL) is the most common primary liver tumor in children, and is usually diagnosed during the first 3 years of life. Collaborative multicenter studies have led to improved diagnostic and treatment strategies. The pretreatment extent of disease (PRETEXT) staging system has become a consensus classification, and an international pathological classification system has also been developed. Clinical trials examining multimodal therapy, which consists of complete surgical resection plus liver transplantation and chemotherapy, have led to improved outcomes for children with HBL. Recently, the Children's Hepatic Tumors International Collaboration (CHIC), which includes major multicenter study groups, created a shared database that merges data on all children underwent therapy in the clinical trials of these groups until 2008. CHIC has developed a global approach to risk stratification of pediatric HBL for use in future global clinical trials. The aim of this review is to report the recent developments on the diagnosis and treatment of pediatric HBL.

Management of hepatoblastoma: an update

PURPOSE OF REVIEW

To summarize the current standards and guidelines for the diagnosis and management of hepatoblastoma, a rare pediatric liver tumor.

RECENT FINDINGS

Hepatoblastoma is the most common malignant liver tumor in childhood. International collaborative efforts have led to uniform implementation of the pretreatment extent of disease (PRETEXT) staging system as a means to establish consensus classification and assess upfront resectability. Additionally, current histopathological classification, in light of more advanced molecular profiling and immunohistochemical techniques and integration of tumor biomarkers into risk stratification, is reviewed. Multimodal therapy is composed of chemotherapy and surgical intervention. Achievement of complete surgical resection plays a key role in successful treatment for hepatoblastoma. Overall, outcomes have greatly improved over the past four decades because of advances in chemotherapeutic agents and administration protocols as well as innovations of surgical approach, including the use of vascular exclusion, ultrasonic dissection techniques, and liver transplantation. Challenges remain in management of high-risk patients as well as patients with recurrent or metastatic disease.

SUMMARY

Eventually, a more individualized approach to treating the different types of the heterogeneous spectrum of hepatoblastoma, in terms of different chemotherapeutic protocols and timing as well as type and extent of surgery, may become the basis of successful treatment in the more complex or advanced types of hepatoblastoma.

Malignant rhabdoid tumor of the liver presented with initial tumor rupture

Malignant rhabdoid tumor (MRT) of the liver is a rare, highly aggressive tumor of early childhood. We report a 6-month-old boy who was diagnosed with MRT of the liver and presented with spontaneous tumor rupture. The patient underwent intensified chemotherapy and a radical surgical procedure. Twenty four months from the time of the diagnosis, he is alive without evidence of disease. This is the second report of prolonged survival after initial rupture of hepatic MRT.

Primary atypical teratoid/rhabdoid tumor of central nervous system in children: a clinicopathological analysis and review of literature in China

Atypical teratoid/rhabdoid tumor (AT/RT) is a very rare and highly malignant embryonal tumor in the central nervous system (CNS). Five patients (4 girls and 1 boy) with AT/RT were treated in our hospital. The clinical histories, symptoms, neuroimaging aspects, therapies, histological and immunohistochemical findings and follow-up information were reviewed. The patients ranged from 8 to 40 months with a mean age of 20.6 months. One tumor was located in the spinal cord, two in cerebellum and two in the pineal region. The imagings of the tumors resemble medulloblastomas. Pathological examinations showed that one patient had medulloblastoma differentiation, one had choroid plexus carcinoma differentiation, and one had mesenchymal components. Immunohistochemical staining showed that all of the tumors lost the nuclear expression of integrase interactor 1 (INI1), and were positive for Vimentin, S-100 protein and epithelial membrane antigen. One case with no recurrence after 24 months may have benefited from radical excision and postoperative radiotherapy. The other 4 patients died 8, 4, 1 and 1-month respectively after operation without radiotherapy. The diagnosis of AT/RT depends on full sampling, careful observation the morphological characteristics and INI1 examination, even when the tumor are presented in uncommon sites, such as the spinal cord and the pineal region.

Driver mutations of cancer epigenomes

Epigenetic alterations are associated with all aspects of cancer, from tumor initiation to cancer progression and metastasis. It is now well understood that both losses and gains of DNA methylation as well as altered chromatin organization contribute significantly to cancer-associated phenotypes. More recently, new sequencing technologies have allowed the identification of driver mutations in epigenetic regulators, providing a mechanistic link between the cancer epigenome and genetic alterations. Oncogenic activating mutations are now known to occur in a number of epigenetic modifiers (i.e. IDH1/2, EZH2, DNMT3A), pinpointing epigenetic pathways that are involved in tumorigenesis. Similarly, investigations into the role of inactivating mutations in chromatin modifiers (i.e. KDM6A, CREBBP/EP300, SMARCB1) implicate many of these genes as tumor suppressors. Intriguingly, a number of neoplasms are defined by a plethora of mutations in epigenetic regulators, including renal, bladder, and adenoid cystic carcinomas. Particularly striking is the discovery of frequent histone H3.3 mutations in pediatric glioma, a particularly aggressive neoplasm that has long remained poorly understood. Cancer epigenetics is a relatively new, promising frontier with much potential for improving cancer outcomes. Already, therapies such as 5-azacytidine and decitabine have proven that targeting epigenetic alterations in cancer can lead to tangible benefits. Understanding how genetic alterations give rise to the cancer epigenome will offer new possibilities for developing better prognostic and therapeutic strategies.

Towards an international pediatric liver tumor consensus classification: proceedings of the Los Angeles COG liver tumors symposium

Liver tumors are rare in children, and their diagnoses may be challenging particularly because of the lack of a current consensus classification system. Systematic central histopathological review of these tumors performed as part of the pediatric collaborative therapeutic protocols has allowed the identification of histologic subtypes with distinct clinical associations. As a result, histopathology has been incorporated within the Children's Oncology Group (COG) protocols, and only in the United States, as a risk-stratification parameter and for patient management. Therefore, the COG Liver Tumor Committee sponsored an International Pathology Symposium in March 2011 to discuss the histopathology and classification of pediatric liver tumors, and hepatoblastoma in particular, and work towards an International Pediatric Liver Tumors Consensus Classification that would be required for international collaborative projects. Twenty-two pathologists and experts in pediatric liver tumors, including those serving as central reviewers for the COG, European Société Internationale d'Oncologie Pédiatrique, Gesellschaft für Pädiatrische Onkologie und Hämatologie, and Japanese Study Group for Pediatric Liver Tumors protocols, as well as pediatric oncologists and surgeons specialized in this field, reviewed more than 50 pediatric liver tumor cases and discussed classic and newly reported entities, as well as criteria for their classification. This symposium represented the first collaborative step to develop a classification that may lead to a common treatment-stratification system incorporating tumor histopathology. A standardized, clinically meaningful classification will also be necessary to allow the integration of new biological parameters and to move towards clinical algorithms based on patient characteristics and tumor genetics, which should improve future patient management and outcome.

Hepatoblastoma state of the art: pathology, genetics, risk stratification, and chemotherapy

PURPOSE OF REVIEW

As a rare pediatric tumor, hepatoblastoma presents challenges to the individual practitioner as no center will see more than a handful of cases each year.

RECENT FINDINGS

The Children's Hepatic tumor International Collaborative (CHIC) effort has fostered international cooperation in this rare children's tumor, leading to the establishment of a large international collaborative dataset, the CHIC database, which has been interrogated to refine risk stratification and inform treatment options. Apace with this effort has been the international collaboration of pediatric pathologists working together to establish a new international histopathologic consensus classification for pediatric liver tumors as a whole, with particular focus on the histological subtypes of hepatoblastoma.

SUMMARY

International collaborative efforts in hepatoblastoma have led to a new international histopathologic consensus classification, refinements in risk stratification, advances in chemotherapy, and a better understanding of surgical resection options forming the foundation for the development of an upcoming international therapeutic trial.

Outcomes for patients with congenital hepatoblastoma

BACKGROUND

Congenital hepatoblastoma, diagnosed in the first month of life, has been reported to have a poor prognosis; however, a comprehensive evaluation of this entity is lacking.

PROCEDURE

We retrospectively reviewed two patients from the senior authors' personal series and 25 cases identified in the databases of several multicenter group studies (INT-0098, P9645, 881, P9346, HB 89, HB94, and HB 99). We compared this series with cases of congenital hepatoblastoma previously published in the literature.

RESULTS

The 3-year survival in our case series was 86% (18/21) with a follow-up of 44-230 months (median 85.5 months). Presentation and treatment were not substantially different from hepatoblastoma cohorts unselected for age. Survival was comparable to the reported disease free survival for a similar cohort of hepatoblastoma patients unselected for age between 1986 and 2002 (82.5%) [von Schweinitz et al., Eur J Cancer 1997; 33:1243-1249]. The 2-year survival of cases reported in the literature was 0% (0/9) and 42% (10/24) for patients reported before and after 1990, respectively.

CONCLUSIONS

Congenital hepatoblastoma does not appear to confer a worse prognosis. The improved survival of our current series of patients, collected from the past 20 years of German and American multicenter trials and personal series, suggests that the outcome of hepatoblastoma at this young age is much better than has been historically reported. More rigorous analysis should be conducted in future multicenter trials. It is possible that congenital hepatoblastoma should be treated like all other patients with hepatoblastoma provided that the child is stable enough to proceed with surgery and chemotherapy.

Fibroblast growth factor receptors as novel therapeutic targets in SNF5-deleted malignant rhabdoid tumors

Malignant rhabdoid tumors (MRTs) are aggressive pediatric cancers arising in brain, kidney and soft tissues, which are characterized by loss of the tumor suppressor SNF5/SMARCB1. MRTs are poorly responsive to chemotherapy and thus a high unmet clinical need exists for novel therapies for MRT patients. SNF5 is a core subunit of the SWI/SNF chromatin remodeling complex which affects gene expression by nucleosome remodeling. Here, we report that loss of SNF5 function correlates with increased expression of fibroblast growth factor receptors (FGFRs) in MRT cell lines and primary tumors and that re-expression of SNF5 in MRT cells causes a marked repression of FGFR expression. Conversely, siRNA-mediated impairment of SWI/SNF function leads to elevated levels of FGFR2 in human fibroblasts. In vivo, treatment with NVP-BGJ398, a selective FGFR inhibitor, blocks progression of a murine MRT model. Hence, we identify FGFR signaling as an aberrantly activated oncogenic pathway in MRTs and propose pharmacological inhibition of FGFRs as a potential novel clinical therapy for MRTs.

Current therapeutic strategies for childhood hepatic tumors: surgical and interventional treatments for hepatoblastoma

Surgery is the mainstay of multimodal treatment for hepatoblastomas. Among the various staging systems used, PRETEXT is currently adopted in all major study groups worldwide as a common pretreatment staging system. Although variations of treatment strategies among study groups exist, the majority of hepatoblastoma cases currently undergo preoperative chemotherapy. It is therefore critical to determine the optimal surgical treatment during the initial courses of chemotherapy. Patients with PRETEXT IV tumors, multifocal tumors and tumors invading major vessels of the liver are candidates for liver transplantation. Liver transplantation requires preparation in advance, and consultation to a liver expertise team must take place no later than after two cycles of chemotherapy. The existence of pulmonary metastasis is a predictor of poor prognosis of the patient. Surgery for pulmonary nodules should be considered for those patients remaining positive after cycles of chemotherapy. A considerable number of patients have been reported to achieve long-term survival after resecting pulmonary metastasis. The existence of pulmonary metastasis at diagnosis is no longer a contraindication for liver transplantation, provided that the pulmonary nodules are eliminated by chemotherapy or by metastasectomy. Transcatheter arterial chemoembolization (TACE) is a useful tool for the local control of hepatoblastomas, although there are very few reports statistically supporting the significant advantage of this treatment modality. Based on individual cases, TACE could be beneficial in maximizing the anti-tumor effect with less toxic side effects.

Children's Oncology Group's 2013 blueprint for research: rare tumors

In the US, approximately 2,000 children are diagnosed with rare cancers each year, with 5-year survival ranging from <20% for children with advanced carcinomas to >95% for children with intraocular retinoblastoma or localized germ cell tumors. During the last years, 12 clinical studies have been successfully completed in children with retinoblastoma, liver tumors, germ cell tumors, and infrequent malignancies, including therapeutic, epidemiologic, and biologic studies. Current efforts are centered in the development of large international collaborations to consolidate evidence-based definitions and risk stratifications that will support international Phase 3 clinical trials in germ cell tumors, hepatoblastoma, and other rare cancers.

Analysis of national and single-center incidence and survival after liver transplantation for hepatoblastoma: new trends and future opportunities

BACKGROUND

Liver transplantation (LTx) for hepatoblastoma appears to be increasing. Favorable tumor histology is increasingly linked to survival after surgical resection and could also determine posttransplantation outcomes.

METHODS

To evaluate national trends in tumor and LTx incidence as the basis for observations at some LTx centers, and determinants of survival after LTx for hepatoblastoma, we queried the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) registry representing 9.451% of the U.S. population (1975-2007), the United Network for Organ Sharing (UNOS, 1988-2010, n = 332), and Children's Hospital of Pittsburgh database (CHP, 1987-2011, n = 35).

RESULTS

In the United States, hepatoblastoma cases increased 4-fold, LTx for hepatoblastoma increased 20-fold, and hepatoblastoma surpassed other unresectable liver malignancies requiring LTx by nearly 3-fold. Actuarial 5-year patient survival exceeded 75%. Recurrences in 16% were greater after segmental LTx in the total U.S. experience (P = .049). At CHP, 5 children died from recurrences (n = 4) and sepsis (n = 1). Tumors were epithelial (57%) or mixed epithelial-stromal (42%), Children's Oncology Group stage III (77%) or IV (23%). Recurrences were related to previous pulmonary metastases (P = .016), and tumor necrosis <50% (P = .013), but not to small cell undifferentiated tumor histology (P = NS). Hepatic artery thrombosis was more common after LTx for hepatoblastoma compared with nonmalignant indications (P = .0089). Thirty-three children received pre-LTx chemotherapy, 88.6% with cisplatin, and 85.7% received post-LTx chemotherapy.

CONCLUSION

Outcomes after LTx for hepatoblastoma may benefit from improved detection and treatment of pretransplantation metastases, adequate tumor lysis after chemotherapy, and perioperative antithrombotic agents but are unaffected by undifferentiated tumor histology.

Epithelioid sarcoma is associated with a high percentage of SMARCB1 deletions

SMARCB1 gene alterations were first described in highly malignant rhabdoid tumors of the kidney, brain (atypical teratoid/rhabdoid tumor) and soft tissue. An increasing number of tumors have now shown loss of SMARCB1 protein expression by immunohistochemistry, including the majority of epithelioid sarcomas. However, investigations of SMARCB1 gene alterations in epithelioid sarcoma have produced conflicting results. The aim of this study was to evaluate SMARCB1 status using Sanger sequencing of the coding region and multiplex ligation-dependent probe amplification, a rapid and sensitive method for detecting intragenic deletions and duplications, which has not been used in previous studies. Twenty-one epithelioid sarcomas of both classical and proximal type were selected for SMARCB1 gene testing and SMARCB1 immunohistochemistry. Nineteen of 21 (90%) epithelioid sarcomas were SMARCB1 negative by immunohistochemistry. Twelve of the 19 (63%) had adequate DNA recovery for evaluation. Ten of 12 (83%) tumors showed homozygous deletions of the gene. Two cases showed heterozygous deletions and polymorphisms, but no sequence mutations. These results confirm the high frequency of SMARCB1 deletions in epithelioid sarcoma and show that multiplex ligation-dependent probe amplification is a reliable method for detection of deletions in these cases, which can be performed on formalin-fixed, paraffin-embedded tissue. Given the high percentage of SMARCB1 alterations in epithelioid sarcoma, these findings argue against using SMARCB1 gene deletion as a tool in distinguishing them from malignant rhabdoid tumors.

[Chromatin remodeling defects and cancer: the SWI/SNF example]

The SWI/SNF complex is a multiprotein complex essential for chromatin remodelling. As such, it plays a key role in the epigenetic regulation of genome expression. This complex is composed of a dozen of proteins, some of which are constant and ubiquitous, especially SMARCB1 and SMARCA4. Mutations in these genes are now described in an increasing number of tumors. Mutations in SMARCB1 characterize the majority of rhabdoid tumors, an aggressive malignancy that exquisitely depends on this single genetic event. Rare rhabdoid tumors have mutation in SMARCA4, a genetic abnormality also found in some medulloblastomas. Many other tumor types, of variable aggressiveness, show an abnormal loss of expression of SMARCB1, but the genetic underlying cause most often remains elusive. The recent sequencings of whole exomes have described frequent mutations in other genes of the SWI/SNF complex: mutations in ARID1A in liver, gastric or bladder carcinomas, and PBRM1 mutations in renal cancers. These data establish the wide role of SWI/SNF complex in cancers and justify that major efforts should now be devoted to this common mechanism of human oncogenesis.

A rare case of adult hepatoblastoma with neuroendocrine differentiation misdiagnosed as neuroendocrine tumor

Hepatoblastoma is the most common malignant liver tumor between the age of 6 months and 3 years, but it is extremely rare in adults. Only Forty-five cases of adult hepatoblastoma were reported up to now in the world. Hepatoblastoma exhibits a wide range of epithelial and mesenchymal lines differentiation, but neuroendocrine differentiation of this tumor has rare been reported in the literature. Here, we reported a case of primary giant hepatoblastoma (about 11.4*7.9*15.3 cm) with neuroendocrine differentiation of a 32-year-old woman, which was misdiagnosed as neuroendocrine tumor.

Nucleosome occupancy and gene regulation during tumorigenesis

Nucleosomes are the basic structural units of eukaryotic chromatin. In recent years, it has become evident that nucleosomes and their position, in concert with other epigenetic mechanisms (such as DNA methylation, histone modifications, changes in histone variants, as well as small noncoding regulatory RNAs) play essential roles in the control of gene expression. Here, we discuss the mechanisms and factors that regulate nucleosome position and gene expression in normal and cancer cells.

Current issues and controversies in the classification of pediatric hepatocellular tumors

Systematic histopathologic examination of hepatoblastoma specimens from patients enrolled in therapeutic protocols has allowed the identification of clinically relevant histologic subtypes that are being incorporated into risk stratification systems. Genetic and molecular studies have documented recurrent chromosomal abnormalities and aberrant activation of developmental, and oncogenic signaling pathways in hepatoblastoma. Molecular profiling has also identified molecular subclasses and gene signatures that could be used to stratify hepatoblastoma patients. Future international collaboration is needed to develop consensus pathology classifications, and to progressively incorporate genetic and molecular biomarkers into therapeutic pediatric liver tumors protocols.

Genetics and epigenetics of hepatoblastoma

A number of unique genetic features are observed in hepatoblastoma that have provided insights into the origins of hepatoblastoma. Hallmark cytogenetic changes in hepatoblastoma include the acquisition of additional copies of whole chromosomes and a recurring unbalanced translocation involving 1q. Genetic syndromes are associated with approximately 15% of hepatoblastoma and the understanding and recognition of these syndromes will be important in determining future surveillance studies needed to prevent additional cancers in survivors as well as in some case guide the care of family members. This article will review the genetic changes, both germ line and acquired, that are recurring events in hepatoblastoma, with emphasis on how these genetic changes could work together with other developmental factors and influence cancer predisposition, tumor growth, as well as aid in prognosis. Tumor-specific signatures based on transcriptional or epigenetic alterations will be reviewed that might be used in the future to better diagnose and subtype the disease as well as predict prognosis and response to therapy.

Chemotherapeutic approaches for newly diagnosed hepatoblastoma: past, present, and future strategies

Surgical resection is the foundation of therapy in hepatoblastoma (HB), yet most patients have unresectable tumors at diagnosis. Patients with resectable tumors have event-free survival (EFS) of 80-90% and can be cured with cisplatin, 5-fluorouracil, and vincristine. Patients whose tumors are unresectable but without overt metastases at diagnosis have EFS of 60-70%, and many can be rendered resectable without doxorubicin. Children with metastatic disease have fared poorly with 20-50% EFS, and new approaches for these patients remain desperately needed. Dose intensification of cisplatin and doxorubicin appears beneficial in high-risk patients. Future treatment strategies, which may be useful, include increasing intensity and/or duration of therapy, developing a maintenance regimen (oral irinotecan), using liver transplantation more often for patients to undergo complete resection, and identifying and incorporating novel agents. A better understanding of the biologic and pathologic factors is critical for predicting tumor behavior and developing more logical risk-based treatments.

Hepatoblastoma clinical research: lessons learned and future challenges

The past four decades has brought significant improvement to the diagnosis, treatment, and outcomes of children diagnosed with hepatoblastoma. These improvements are the results of multidisciplinary and multi-institutional international cooperative trials, such as those conducted by the Children's Oncology Group (COG) or the International Childhood Liver Tumor Strategy Group (SIOPEL) and national studies such as those conducted in Germany and Japan. Due to the different treatment strategies used by the various groups, the information generated has been at times complementary but at other times contradictory. In this manuscript, we will provide a global picture of where "we stand and where we are going" in regards to clinical research of childhood hepatoblastoma. We will focus on lessons learned, especially in reference to the experiences of the COG and SIOPEL study groups, and discuss future challenges.

Surgical treatment of hepatoblastoma

Surgical resection remains the cornerstone of cure in hepatoblastoma (HB). Meticulous review of contrast enhanced CT/MR imaging facilitates PRETEXT and POST-TEXT grouping to determine optimal timing and desired extent of liver resection. Excellent knowledge of liver anatomy is essential and the dissection must ensure protection of the vascular inflow and outflow to the remaining liver at all times. Referral to a liver specialty center in advanced cases may facilitate resectability. Potential surgical complications include bleeding, vascular injury, cardiac arrest, liver failure, and bile leak. The risk of complications can be minimized with preoperative planning, appropriate referral, and precise surgical technique.

Molecular inversion probe analysis detects novel copy number alterations in Ewing sarcoma

Ewing sarcoma (ES) is the second most common bone tumor in children and young adults, with dismal outcomes for metastatic and relapsed disease. To better understand the molecular pathogenesis of ES and to identify new prognostic markers, we used molecular inversion probes (MIPs) to evaluate copy number alterations (CNAs) and loss of heterozygosity (LOH) in formalin-fixed paraffin-embedded (FFPE) samples, which included 40 ES primary tumors and 12 ES metastatic lesions. CNAs were correlated with clinical features and outcome, and validated by immunohistochemistry (IHC). We identified previously reported CNAs, in addition to SMARCB1 (INI1/SNF5) homozygous loss and copy neutral LOH. IHC confirmed SMARCB1 protein loss in 7-10% of clinically diagnosed ES tumors in three separate cohorts (University of Utah [N = 40], Children's Oncology Group [N = 31], and University of Michigan [N = 55]). A multifactor copy number (MCN)-index was highly predictive of overall survival (39% vs. 100%, P < 0.001). We also identified RELN gene deletions unique to 25% of ES metastatic samples. In summary, we identified both known and novel CNAs using MIP technology for the first time in FFPE samples from patients with ES. CNAs detected by microarray correlate with outcome and may be useful for risk stratification in future clinical trials.

Malignant liver tumors

Malignant tumors of the liver comprise a relatively small fraction of the total number of pediatric malignancies. However, these tumors can be a significant cause of morbidity and mortality, and there have been significant therapeutic gains during the past few decades through advances in systemic therapy and surgical treatment. Even in patients with advanced local disease, complete resection is now a possibility because of improvements in liver transplantation techniques. In this review, we will discuss the staging and treatment of common malignant tumors of the liver.

Renal and hepatic tumors in the neonatal period

Renal and hepatic tumors in neonates are extremely rare. Nevertheless it is important for clinicians to be familiar with them. Both renal and hepatic neonatal tumors are heterogeneous collections of several tumor types. Some renal and hepatic tumors are benign and may require no interventions whereas others can be associated with significant morbidity and even mortality and may require multimodality treatment. Early diagnosis and initiation of the proper treatment plan is crucial for achieving the best outcomes for these rare tumors in this vulnerable population.

Soft tissue tumors of uncertain origin

Many soft tissue tumors of childhood lack obvious differentiation toward a defined mesenchymal tissue type or have a phenotype that does not correspond to any defined normal tissue. These challenging tumors are currently regarded as neoplasms of uncertain differentiation. Nonetheless, there have been great strides in the understanding of their pathologic and genetic features and biologic underpinnings. The application of new genetic information to the pathologic diagnosis among this group of tumors is an emerging area in diagnostic pediatric pathology. This article reviews the clinicopathologic features of tumors of uncertain and/or miscellaneous origin, with an emphasis on the unique aspects of these neoplasms in children and adolescents, use of diagnostic adjuncts, and differential diagnosis.

Role of epigenetics in cancer initiation and progression

The epigenome which comprises DNA methylation, histone modifications, chromatin structures and non-coding RNAs controls gene expression patterns. In cancer cells, there are aberrant changes in the epigenome. The question in cancer epigenetics is that whether these changes are the cause of cell transformation, or rather the consequence of it. We will discuss the epigenetic phenomenon in cancer, as well as the recent interests in the epigenetic reprogramming events, and their implications in the cancer stem cell theory. We will also look at the progression of cancers as they become more aggressive, with focus on the role of epigenetics in tumor metastases exemplified with the urokinase plasminogen activator (uPA) system. Last but not least, with therapeutics intervention in mind, we will highlight the importance of balance in the design of epigenetic based anti-cancer therapeutic strategies.

[Paediatric malignant liver tumours]

Tumours and pseudotumours of the liver are a heterogeneous group of neoplasm including 60% of malignant tumours. Malignant liver tumours account for less than 2% of the lesions in children and vary considerably in incidence throughout the paediatric age range, with hepatoblastoma, rhabdoid tumour of the liver, hemangioendothelioma, biliary tract rhabdomysosarcoma and mesenchymal hamartoma in the first two years of life and hepatocellular carcinoma, focal nodular hyperplasia, and undifferentiated sarcoma in older children and adolescents. Treatment of malignant epithelial tumours is based on the surgical resection of the tumour associated with pre- and postoperative chemotherapy including cisplatinum. Modalities of the treatment are adapted to risk factors. Survival rates at three years are over 80% for localised hepatoblastoma whereas they are less than 30% in hepatocellular carcinomas. The role of targeted therapies still has to be defined.

Hepatoblastoma: recent developments in research and treatment

Hepatoblastoma is the most common liver tumor of early childhood. According to recent studies its incidence seems to be increasing in North America and Europe. Since new histological variants have been described recently the formerly clear-cut distinction of hepatoblastoma and hepatocellular carcinoma may not be valid anymore and a new histological classification will be inaugurated by an international working group. Recent research identified prognostically relevant gene signatures as well as potential molecular targets for therapy of hepatoblastoma. The multicentric study groups in the USA, Europe and Japan recommend cisplatin based chemotherapy for neoadjuvant and adjuvant treatment. However, their risk stratification systems and general treatment strategies differ substantially. Therefore the four groups agreed to pool their patients' data for an analysis of prognostic criteria which can be used for defining common risk groups. While 90% of standard risk and 65% of high risk hepatoblastomas can be cured, the still dismal outcome of multifocal disseminated and metastasising tumors warrants the investigation of new cytotoxic drugs and substances against specific molecular targets.

Claudin-6 is a nonspecific marker for malignant rhabdoid and other pediatric tumors

Claudins are tight junction proteins with claudin-6 (CLDN6) expression mostly restricted to embryonic and fetal life. Previously reported gene expression microarray analysis showed an increased level of CLDN6 in atypical teratoid rhabdoid tumors (AT/RT) compared with other central nervous system (CNS) tumors and sarcomas. However, there exist conflicting data on expression of CLDN6 as assessed by immunohistochemistry in CNS tumors. We established membranous staining as a specific and reproducible method for evaluating CLDN6 expression based on fetal and adolescent controls. We then evaluated a large group (257) of pediatric tumors using tissue microarrays, including: 47 malignant rhabdoid tumors (MRTs), (31 AT/RTs and 16 non-CNS MRTs); 67 small, round, blue cell tumors (10 Wilms tumors, 10 embryonal rhabdomyosarcomas, 10 neuroblastomas (NBs), 10 synovial sarcomas (SSs), 9 hepatoblastomas (HBs), 9 alveolar rhabdomyosarcomas, and 9 Ewings sarcomas); and 143 CNS tumors (24 medulloblastomas, 21 pilocytic astrocytomas, 14 astrocytomas grade II/III, 13 gangliogliomas, 12 glioblastomas, 12 ependymal tumors, 11 choroid plexus tumors, 10 meningiomas, 8 dysembryoplastic neuroepithelial tumors, 8 oligodendrogliomas, 4 craniopharyngiomas, 2 germinomas, 2 primitive neuroectodermal tumors (PNET), and 2 central neurocytomas). CLDN6 expression was seen in 12 of 31 (39%) AT/RTs, 7 of 16 (44%) non-CNS MRTs, 5 of 10 (50%) Wilms tumors, 1 of 9 (11%) HBs, 2 of 2 (100%) germinomas, 1 of 2 (50%) CNS PNETs, 1 of 24 (4%) medulloblastomas, and 1 of 10 (10%) meningiomas. Ten of 11 (91%) choroid plexus tumors showed apical staining but no concentric membranous staining. Although CLDN6 is expressed in both AT/RTs and MRTs, it is not a specific biomarker as it is expressed in a variety of other pediatric CNS and soft tissue tumors.

Diverse functions of ATP-dependent chromatin remodeling complexes in development and cancer

Mammalian SWI/SNF like Brg1/Brm associated factors (BAF) chromatin-remodeling complexes are able to use energy derived from adenosine triphosphate (ATP) hydrolysis to change chromatin structures and regulate nuclear processes such as transcription. BAF complexes contain multiple subunits and the diverse subunit compositions provide functional specificities to BAF complexes. In this review, we summarize the functions of BAF subunits during mammalian development and in progression of various cancers. The mechanisms underlying the functional diversity and specificities of BAF complexes will be discussed.

INI1-deficient tumors: diagnostic features and molecular genetics

Significant progress has been made in understanding the molecular genetic alterations involved in sarcomagenesis. Cytogenetic and molecular studies have identified nonrandom genetic abnormalities, including tumor suppressor gene inactivation. Mutations, deletions, and other somatic alterations in the tumor suppressor gene INI1 (hSNF5; SMARCB1), which encodes a subunit of the SWI/SNF chromatin remodeling complex, were first described in the malignant rhabdoid tumor of infancy. Since then, INI1 has also been implicated in the pathogenesis of additional tumor types including renal medullary carcinomas and epithelioid sarcomas and a subset of epithelioid malignant peripheral nerve sheath tumors, myoepithelial carcinomas, and extraskeletal myxoid chondrosarcomas. As varied as this group appears, they all show loss of INI1 protein expression, a propensity for rhabdoid cytomorphology, and sometimes other overlapping immunohistochemical and histologic findings. We will review the clinicopathologic features of these tumor types and emphasize the clinical utility of INI1 immunohistochemistry in differential diagnosis.

Rhabdoid tumors of the liver: rare, aggressive, and poorly responsive to standard cytotoxic chemotherapy

BACKGROUND

Rhabdoid tumors of the liver are rare tumors that are difficult to cure. We compiled all the cases previously reported in the literature to review clinical data, treatments, and outcomes.

PROCEDURE

Patients were identified by literature review using PubMed.

RESULTS

Thirty-four patients were identified. The median age at presentation was 8 months. All patients with reported AFP results exhibited normal or minimally increased serum AFP levels. All 10 tumors with reported INI1 immunohistochemistry results were reported as negative. Twenty-one patients presented with metastatic disease at diagnosis. Thirty patients died of disease or treatment complications. Most deaths occurred within 12 months after diagnosis. Five patients survived at the time of the reports with one patient alive with disease. One patient relapsed and subsequently died after the report was published. Of the four patients alive without disease, all were treated with chemotherapy, and at least three had surgery or transplantation. Two patients received radiation therapy but did not survive.

CONCLUSIONS

Rhabdoid tumors of the liver are aggressive, rare tumors of the infant liver that are often associated with metastases at the time of diagnosis. Mortality is high and often occurs soon after diagnosis. Treatment with aggressive chemotherapy in combination (especially an alkylating agents doxorubicin) with complete resection may lead to improved outcomes. Therapy targeted to the INI1 mutation of these tumors is currently being investigated and may offer greater hope of cure.

Molecularly confirmed primary malignant rhabdoid tumor of the urinary bladder: implications of accurate diagnosis

Malignant rhabdoid tumors (MRTs) are well recognized in the kidney and extrarenal sites such as soft tissues, retroperitoneum, and bladder but are classified as atypical teratoid/rhabdoid tumors in the central nervous system. The unifying features of both extracranial MRT and atypical teratoid/rhabdoid tumors are the exon deletions/mutations of the SMARCB1 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily b, member 1) gene in 22q11.23 and resulting loss of SMARCB1/INI1 (integrase interactor 1) protein expression by immunohistochemistry. We herein report a case of extrarenal rhabdoid tumor confined to the bladder in a 3-year-old child, diagnosed by histopathology and confirmed by immunohistochemical and molecular studies. This is only the fourth molecularly proven primary MRT of the bladder to be reported. The patient's peripheral blood was negative for the deletions observed in the tumor, thereby confirming a sporadic origin for the tumor. Given the possible dismal outcome, urgency for definitive diagnosis to institute intensive multimodality therapy, histopathologic differential diagnosis with rhabdomyosarcoma and urothelial carcinoma with rhabdoid features, and lack of consensus management guidelines, oncologists, urologists, and pathologists must be aware of this entity. Evaluation for a germ line SMARCB1 alteration may greatly aid risk stratification and family planning.

Complete surgical resection is curative for children with hepatoblastoma with pure fetal histology: a report from the Children's Oncology Group

PURPOSE

Children with pure fetal histology (PFH) hepatoblastoma treated with complete surgical resection and minimal adjuvant therapy have been shown to have excellent outcomes when compared with other patients with hepatoblastoma. We prospectively studied the safety and efficacy of reducing therapy in all children with stage I PFH enrolled onto two consecutive studies.

PATIENTS AND METHODS

From August 1989 to December 1992, 9 children with stage I PFH were treated on the Intergroup Hepatoblastoma study INT-0098 and were nonrandomly assigned to receive chemotherapy after surgical resection with single-agent bolus doxorubicin for 3 consecutive days. From March 1999 to November 2006, 16 children with stage I PFH enrolled onto Children's Oncology Group Study P9645 were treated with observation after resection. Central confirmation of the histologic diagnosis by a study group pathologist was mandated. The extent of liver disease was assigned retrospectively according to the pretreatment extent of disease (PRETEXT) system and is designated "retro-PRETEXT" to clarify the retrospective group assignment.

RESULTS

Five-year event-free and overall survival for the 9 patients treated on INT-0098 were 100%. All 16 patients enrolled onto the P9645 study were alive and free of disease at the time of last contact, with a median follow-up of 4.9 years. Retro-PRETEXT for the 21 patients with available data revealed seven patients with stage I disease, 10 patients with stage II disease, and four patients with stage III disease.

CONCLUSION

Children with completely resected PFH hepatoblastoma can achieve long-term survival without additional chemotherapy. When feasible, surgical resection of hepatoblastoma at diagnosis, without chemotherapy, can identify children for whom no additional therapy is necessary.

SWI/SNF nucleosome remodellers and cancer

SWI/SNF chromatin remodelling complexes use the energy of ATP hydrolysis to remodel nucleosomes and to modulate transcription. Growing evidence indicates that these complexes have a widespread role in tumour suppression, as inactivating mutations in several SWI/SNF subunits have recently been identified at a high frequency in a variety of cancers. However, the mechanisms by which mutations in these complexes drive tumorigenesis are unclear. In this Review we discuss the contributions of SWI/SNF mutations to cancer formation, examine their normal functions and discuss opportunities for novel therapeutic interventions for SWI/SNF-mutant cancers.

Spectrum of SMARCB1/INI1 mutations in familial and sporadic rhabdoid tumors

BACKGROUND

Germline mutations and deletions of SMARCB1/INI1 in chromosome band 22q11.2 predispose patients to rhabdoid tumor and schwannomatosis. Previous estimates suggested that 15-20% of rhabdoid tumors were caused by an underlying germline abnormality of SMARCB1. However, these studies were limited by case selection and an inability to detect intragenic deletions and duplications.

PROCEDURE

One hundred matched tumor and blood samples from patients with rhabdoid tumors of the brain, kidney, or soft tissues were analyzed for mutations and deletions of SMARCB1 by FISH, multiplex ligation-dependent probe amplification (MLPA), sequence analysis and high resolution Illumina 610K SNP-based oligonucleotide array studies.

RESULTS

Thirty-five of 100 patients were found to have a germline SMARCB1 abnormality. These abnormalities included point and frameshift mutations, intragenic deletions and duplications, and larger deletions including regions both proximal and distal to SMARCB1. There were nine cases that demonstrated parent to child transmission of a mutated copy of SMARCB1. In eight of the nine cases, one or more family members were also diagnosed with rhabdoid tumor or schwannoma, and two of the eight families presented with multiple affected children in a manner consistent with gonadal mosaicism.

CONCLUSIONS

Approximately one-third of newly diagnosed patients with rhabdoid tumor have an underlying genetic predisposition to tumors due to a germline SMARCB1 alteration. Families may demonstrate incomplete penetrance and gonadal mosaicism, which must be considered when counseling families of patients with rhabdoid tumor.

Equine Primary Liver Tumors: A Case Series and Review of the Literature

Hepatoblastoma (HB) is an uncommon pediatric liver tumor in humans and horses. In humans, HB is most frequently diagnosed in fetuses, neonates, and young children, whereas hepatocellular carcinoma (HCC) affects juvenile and adult humans. Hepatoblastoma in the horse is rare, with only 9 reported cases. Affected horses ranged in age from late-term aborted fetuses to 3 years. The current study describes 3 new cases of primary liver tumors in horses and reviews findings in relation to other reports on this condition. Tumors classified as HB were identified in a male Standardbred aborted fetus and in a 4-year-old Thoroughbred filly. Hepatocellular carcinoma was diagnosed in a 15-month-old Paint filly. In the Standardbred fetus, the tumor was only present in the liver. In the Thoroughbred and Paint fillies, primary tumors were in the right liver lobe and at the hilus, respectively, and there were metastases to other lobes (HB) and mesenteric lymph nodes (HCC). Tumors were sharply demarcated from adjacent tissue, nonencapsulated, compressive, and invasive. Consisting of cords and nests, or disorganized sheets of epithelial cells, tumors had variable stromal and vascular components. The fetal tumor contained areas of smaller, less differentiated cells with a pronounced mesenchymal component interpreted to be embryonal hepatic tissue. Diagnoses were based on tumor histomorphologic features, resemblance to hepatocyte developmental stages, age of the animal, and patterns of metastasis. Tumors classified as HB were α-fetoprotein immunoreactive. Primary hepatic tumors in the horse are diverse in morphology and include subtypes compatible with classification criteria applied to human tumors.

INI1 (BAF 47) immunohistochemistry is an essential diagnostic tool for children with hepatic tumors and low alpha fetoprotein

Malignant rhabdoid tumor (MRT) of the liver is a rare malignancy with grave prognosis. This entity should be considered in the differential diagnosis of any aggressive liver tumor with low levels of alpha fetoprotein. We report 2 cases of hepatic MRT presenting in infancy. In these 2 cases, we show that loss of INI1 facilitates making the correct diagnosis of primary hepatic MRT utilizing BAF 47 (INI1 gene product) immunostains. Difficulty encountered in making this rare diagnosis, including the need for repeated biopsies, can be avoided if MRT is considered in the differential diagnosis early on and BAF 47 immunohistochemistry is ordered.

Defining hepatoblastoma responsiveness to induction therapy as measured by tumor volume and serum alpha-fetoprotein kinetics

PURPOSE

Hepatoblastoma is commonly unresectable at presentation, necessitating induction chemotherapy before definitive resection. To refine the paradigm for timing of resection, we questioned whether a plateau in hepatoblastoma responsiveness to neoadjuvant therapy could be detected by calculating tumor volume (TV) and serum alpha-fetoprotein (sAFP) kinetics.

METHODS

To calculate TV and sAFP as measures of treatment responsiveness over time, infants having initially unresectable epithelial-type hepatoblastomas were identified at a single institution (1996-2008). Effects of therapy type, therapy duration, and lobe of liver involvement on TV, sAFP, margin status, and toxicity were analyzed.

RESULTS

Of 24 infants treated for epithelial-type hepatoblastoma during this interval, 5 were resected primarily, and 15 had complete digital films for kinetics analysis. Both TV and sAFP decreased dramatically over time (P < .0001). No statistically significant difference in mean TV or sAFP was detected after chemotherapy cycle 2. Left lobe tumors had greater presenting levels of and significantly slower decay in sAFP compared with right lobe tumors (P = .005), although no statistically significant differences in TV existed between liver lobes. Resection margins did not change with therapy duration.

CONCLUSIONS

Measuring TV and sAFP kinetics accurately reflects hepatoblastoma responsiveness to induction therapy. Treatment toxicities may be reduced by earlier resection and tailoring of chemotherapeutic regimens.