Targeting EpCAM (CD326) for immunotherapy in hepatoblastoma

Overcoming resistance in small-cell lung cancer

INTRODUCTION

Small-cell lung cancer (SCLC) accounts for 15% of lung cancers and has a dismal prognosis due to early dissemination and acquired chemoresistance. The initial good response to chemotherapy is followed by refractory relapses within 1-2 years. Mechanisms leading to chemoresistance are not clear and progress is poor.

AREAS COVERED

This article reviews the current evidence of the resistance of SCLCs at the cellular level including alteration of key proteins and the possible presence of cancer stem cells (CSCs). Without compelling evidence for cellular mechanisms and clinical failures of novel approaches, the study of SCLC has advanced to the role of 3D tumor cell aggregates in chemoresistance.

EXPERT OPINION

The scarcity of viable tumor specimen from relapsed SCLC patients has hampered the investigations of acquired chemoresistance but a panel of nine SCLC circulating tumor cell (CTC) cell lines have revealed characteristics of SCLC in the advanced refractory states. The chemoresistance of relapsed SCLC seems to be linked to the spontaneous formation of large spheroids, termed tumorospheres, which contain resistant quiescent and hypoxic cells shielded by a physical barrier. So far, drugs to tackle large tumor spheroids are in preclinical and early clinical development.

Precision Oncology in Pediatric Cancer Surgery

Pediatric precision oncology has provided a greater understanding of the wide range of molecular alterations in difficult-to-treat or rare tumors with the aims of increasing survival as well as decreasing toxicity and morbidity from current cytotoxic therapies. In this article, the authors discuss the current state of pediatric precision oncology which has increased access to novel targeted therapies while also providing a framework for clinical implementation in this unique population. The authors evaluate the targetable mutations currently under investigation-with a focus on pediatric solid tumors-and discuss the key surgical implications associated with novel targeted therapies.

Immune Regulatory Networks and Therapy of γδ T Cells in Liver Cancer: Recent Trends and Advancements

The roles of γδ T cells in liver cancer, especially in the potential function of immunotherapy due to their direct cytotoxic effects on tumor cells and secretion of important cytokines and chemokines, have aroused research interest. This review briefly describes the basic characteristics of γδ T cells, focusing on their diverse effects on liver cancer. In particular, different subtypes of γδ T cells have diverse or even opposite effects on liver cancer. We provide a detailed description of the immune regulatory network of γδ T cells in liver cancer from two aspects: immune components and nonimmune components. The interactions between various components in this immune regulatory network are dynamic and pluralistic, ultimately determining the biological effects of γδ T cells in liver cancer. We also integrate the current knowledge of γδ T-cell immunotherapy for liver cancer treatment, emphasizing the potential of these cells in liver cancer immunotherapy.

Histopathologic and immunophenotypic characterization of patient-derived pediatric malignant hepatocellular tumor xenografts (PDXs)

Advances in targeted therapies for pediatric hepatocellular tumors have been limited due to a paucity of clinically relevant models. Establishment and validation of intrahepatic patient-derived xenograft (PDX) models would help bridging this gap. The aim of this study is to compare the histomorphologic and immunophenotypic fidelity of patient tumors and their corresponding intrahepatic PDX models. Murine PDX models were established by intrahepatic implantation of patient tumors. Pathology slides from both patients and their corresponding PDX models were reviewed and quantitatively assessed for various histologic components and immunophenotypic markers. Ten PDX models were successfully established from nine patients with pre- (n=3) and post- (n=6) chemotherapy samples; diagnosed of hepatoblastoma (n=8) and hepatocellular neoplasm, not otherwise specified (n=1). Two of nine (22.2%) patients showed ≥75% fetal component; however, the corresponding PDX models did not maintain this fetal differentiation. High grade histology was seen in three patients (33.3%) and overrepresented in six PDX models (60%). Within the subset of three PDXs that were further characterized, significant IHC concordance was seen in all 3 models for CK7, CK19, Ki-67, and p53; and 2 of 3 models for Sox9 and Beta-catenin. GPC-3 and GS showed variable to moderate concordance, while Hepar was the least concordant. Our study shows that in general, the PDX models appear to represent the higher-grade component of the original tumor and show significant concordance for Ki-67, making them appropriate tools for testing new therapies for the most aggressive, therapy-resistant tumors.

An Overview of Advances in Rare Cancer Diagnosis and Treatment

Cancer stands as the leading global cause of mortality, with rare cancer comprising 230 distinct subtypes characterized by infrequent incidence. Despite the inherent challenges in addressing the diagnosis and treatment of rare cancers due to their low occurrence rates, several biomedical breakthroughs have led to significant advancement in both areas. This review provides a comprehensive overview of state-of-the-art diagnostic techniques that encompass new-generation sequencing and multi-omics, coupled with the integration of artificial intelligence and machine learning, that have revolutionized rare cancer diagnosis. In addition, this review highlights the latest innovations in rare cancer therapeutic options, comprising immunotherapy, targeted therapy, transplantation, and drug combination therapy, that have undergone clinical trials and significantly contribute to the tumor remission and overall survival of rare cancer patients. In this review, we summarize recent breakthroughs and insights in the understanding of rare cancer pathophysiology, diagnosis, and therapeutic modalities, as well as the challenges faced in the development of rare cancer diagnosis data interpretation and drug development.

A CD326 monoclonal antibody modified core cross-linked curcumin-polyphosphoester prodrug for targeted delivery and cancer treatment

Stimuli-responsive cross-linked micelles (SCMs) are ideal nanocarriers for anti-cancer drugs. Compared with non-cross-linked micelles, SCMs exhibit superior structural stability. At the same time, the introduction of an environmentally sensitive crosslinker into a drug delivery system allows SCMs to respond to single or multiple stimuli in the tumor microenvironment, which can minimize drug leakage during the blood circulation process. In this study, curcumin (CUR) was modified as the hydrophobic core crosslinker by utilizing the bisphenol structure, and redox sensitive disulfide bonds were introduced to prepare the glutathione (GSH) stimulated responsive core crosslinker (abbreviated as N3-ss-CUR-ss-N3). In addition, amphiphilic polymer APEG-b-PBYP was prepared through the ring opening reaction, and reacted with the crosslinker through the "click" reaction. After being dispersed in the aqueous phase, core cross-linked nanoparticles (CCL NPs) were obtained. Finally, monoclonal antibody CD326 (mAb-CD326) was reduced and coupled to the hydrophilic chain ends to obtain the nanoparticles with surface modified antibodies (R-mAb-CD326@CCL NPs) for further enhancing targeted drug delivery. The structures of the polymer and crosslinker were characterized by 1H NMR, UV-Vis, FT-IR, and GPC. The morphology, size and stability of CCL NPs and R-mAb-CD326@CCL NPs were investigated by DLS and TEM. The in vitro drug release behavior of CCL NPs was also studied. The results showed that the CCL NPs exhibited reduction-responsiveness and were able to release the original drug CUR under 10 mM GSH conditions. Additionally, the CCL NPs exhibited excellent stability in both the simulated body fluid environment and organic solvents. Especially, R-mAb-CD326@CCL NPs can actively target tumor cells and showed better therapeutic efficacy in in vivo experiments with a tumor suppression rate of 78.7%. This work provides a new idea for the design of nano-drugs targeting breast cancer.

Targeted immune activation in pediatric solid tumors: opportunities to complement local control approaches

Surgery or radiation therapy is nearly universally applied for pediatric solid tumors. In many cases, in diverse tumor types, distant metastatic disease is present and evades surgery or radiation. The systemic host response to these local control modalities may lead to a suppression of antitumor immunity, with potential negative impact on the clinical outcomes for patients in this scenario. Emerging evidence suggests that the perioperative immune responses to surgery or radiation can be modulated therapeutically to preserve anti-tumor immunity, with the added benefit of preventing these local control approaches from serving as pro-tumorigenic stimuli. To realize the potential benefit of therapeutic modulation of the systemic response to surgery or radiation on distant disease that evades these modalities, a detailed knowledge of the tumor-specific immunology as well as the immune responses to surgery and radiation is imperative. In this Review we highlight the current understanding of the tumor immune microenvironment for the most common peripheral pediatric solid tumors, the immune responses to surgery and radiation, and current evidence that supports the potential use of immune activating agents in the perioperative window. Finally, we define existing knowledge gaps that limit the current translational potential of modulating perioperative immunity to achieve effective anti-tumor outcomes.

Anti-cancer therapeutic strategies based on HGF/MET, EpCAM, and tumor-stromal cross talk

As an intelligent disease, tumors apply several pathways to evade the immune system. It can use alternative routes to bypass intracellular signaling pathways, such as nuclear factor-κB (NF-κB), Wnt, and mitogen-activated protein (MAP)/phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR). Therefore, these mechanisms lead to therapeutic resistance in cancer. Also, these pathways play important roles in the proliferation, survival, migration, and invasion of cells. In most cancers, these signaling pathways are overactivated, caused by mutation, overexpression, etc. Since numerous molecules share these signaling pathways, the identification of key molecules is crucial to achieve favorable consequences in cancer therapy. One of the key molecules is the mesenchymal-epithelial transition factor (MET; c-Met) and its ligand hepatocyte growth factor (HGF). Another molecule is the epithelial cell adhesion molecule (EpCAM), which its binding is hemophilic. Although both of them are involved in many physiologic processes (especially in embryonic stages), in some cancers, they are overexpressed on epithelial cells. Since they share intracellular pathways, targeting them simultaneously may inhibit substitute pathways that tumor uses to evade the immune system and resistant to therapeutic agents.

Co-Expression of CD34, CD90, OV-6 and Cell-Surface Vimentin Defines Cancer Stem Cells of Hepatoblastoma, Which Are Affected by Hsp90 Inhibitor 17-AAG

Cancer stem cells (CSCs) are nowadays one of the major focuses in tumor research since this subpopulation was revealed to be a great obstacle for successful treatment. The identification of CSCs in pediatric solid tumors harbors major challenges because of the immature character of these tumors. Here, we present CD34, CD90, OV-6 and cell-surface vimentin (csVimentin) as reliable markers to identify CSCs in hepatoblastoma cell lines. We were able to identify CSC characteristics for the subset of CD34⁺CD90⁺OV-6⁺csVimentin⁺-co-expressing cells, such as pluripotency, self-renewal, increased expression of EMT markers and migration. Treatment with Cisplatin as the standard chemotherapeutic drug in hepatoblastoma therapy further revealed the chemo-resistance of this subset, which is a main characteristic of CSCs. When we treated the cells with the Hsp90 inhibitor 17-AAG, we observed a significant reduction in the CSC subset. With our study, we identified CSCs of hepatoblastoma using CD34, CD90, OV-6 and csVimentin. This set of markers could be helpful to estimate the success of novel therapeutic approaches, as resistant CSCs are responsible for tumor relapses.

Immunohistochemical Expression Analysis of EpCAM in Hepatoblastomas

The epithelial cell adhesion molecule (EpCAM) is involved in oncogenesis of hepatoblastomas (HBs). Prior genomic profiling studies showed higher EpCAM expression and worse prognosis in HBs containing primitive histotypes, however, this has not been fully addressed from an immunohistochemical perspective. Our goal is to characterize differential EpCAM immunohistochemistry (EpCAM-IHC) among HBs histotypes. We retrieved 62 HBs from 52 patients. EpCAM-IHC was performed (anti-MOC-31, 1:50 dilution; Cell Marque Corporation, Rocklin, CA) and graded in histotypes using the immunoreactive score. The median age of patients was 2 years (range: 0.4 to 9 y) with a M:F ratio of 1.9. Outcome information was available in 38 patients (alive=30, alive with disease=3, and deceased=5) with median follow-up of 60 months (range: 2 to 171 mo). EpCAM-IHC showed notable overexpression (immunoreactive score >4) in embryonal (89%) and crowded fetal (74%) in contrast to glandular (33%), well-differentiated fetal (32%), and small cell undifferentiated/blastemal (3%) components. Mesenchymal elements were negative. In summary, EpCAM-IHC is helpful to distinguish between epithelial components as it is progressively lost in the transition from embryonal to crowded fetal and into well-differentiated fetal histotypes. Its preferential expression among primitive HBs might have therapeutic and prognostic implications. The significance of its largely negative expression in small cell undifferentiated/blastema is interesting despite its presumed immaturity, deserving further studies.

Advances in the conventional clinical treatment for hepatoblastoma and therapeutic innovation

Background

Hepatoblastoma (HB) is a rare malignancy usually occurring in children under 3 years old. With advancements in surgical techniques and molecular biology, new treatments have been developed.

Data resources

The recent literatures on new treatments, molecular mechanisms and clinical trials for HB were searched and reviewed.

Results

Surgical resection remains the main option for treatment of HB. Although complete resection is recommended, a resection with microscopical positive margins (R1) may have similar 5-year overall survival and 5-year event-free survival (EFS) rates after cisplatin chemotherapy and the control of metastasis, as only once described so far. Indocyanine green-guided surgery can help achieve precise resection. Additionally, associating liver partition and portal vein ligation for staged hepatectomy can rapidly increase future liver remnant volume compared with portal vein ligation or embolization. Cisplatin-containing chemotherapies slightly differ among the guidelines from the International Childhood Liver Tumors Strategy Group (SIOPEL), Children’s Oncology Group (COG) and Chinese Anti-Cancer Association Pediatric Committee (CCCG), and the 3-year EFS rate of patients in SIOPEL and CCCG studies was recently shown to be higher than that in COG studies. Liver transplantation is an option for patients with unresectable HB, and successful cases of autologous liver transplantation have been reported. In addition, effective inhibitors of important targets, such as the mTOR (mammalian target of rapamycin) inhibitor rapamycin, β-catenin inhibitor celecoxib and EpCAM (epithelial cell adhesion molecule) inhibitor catumaxomab, have been demonstrated to reduce the activity of HB cells and to control metastasis in experimental research and clinical trials.

Conclusion

These advances in surgical and medical treatment provide better outcomes for children with HB, and identifying novel targets may lead to the development of future targeted therapies and immunotherapies.

Trial Watch: Tumor-targeting monoclonal antibodies in cancer therapy

In 1997, for the first time in history, a monoclonal antibody (mAb), i.e., the chimeric anti-CD20 molecule rituximab, was approved by the US Food and Drug Administration for use in cancer patients. Since then, the panel of mAbs that are approved by international regulatory agencies for the treatment of hematopoietic and solid malignancies has not stopped to expand, nowadays encompassing a stunning amount of 15 distinct molecules. This therapeutic armamentarium includes mAbs that target tumor-associated antigens, as well as molecules that interfere with tumor-stroma interactions or exert direct immunostimulatory effects. These three classes of mAbs exert antineoplastic activity via distinct mechanisms, which may or may not involve immune effectors other than the mAbs themselves. In previous issues of OncoImmunology, we provided a brief scientific background to the use of mAbs, all types confounded, in cancer therapy, and discussed the results of recent clinical trials investigating the safety and efficacy of this approach. Here, we focus on mAbs that primarily target malignant cells or their interactions with stromal components, as opposed to mAbs that mediate antineoplastic effects by activating the immune system. In particular, we discuss relevant clinical findings that have been published during the last 13 months as well as clinical trials that have been launched in the same period to investigate the therapeutic profile of hitherto investigational tumor-targeting mAbs.

Clinical and Biological Implications of Cancer Stem Cells in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a malignant tumor with poor prognosis, and is one of the leading causes of cancer-related deaths worldwide. Recently, the development of therapeutic drugs via novel mechanisms of action, involving molecular-targeted drugs and immune checkpoint inhibitors, has progressed in the field of HCC. However, the recurrence rate remains high, and further improvement of the prognosis of patients with HCC is urgently needed. Cancer stem cells (CSCs) are a promising target for further development of novel anti-cancer drugs because they are reportedly involved in tumor initiation, maintenance, recurrence, and resistance to conventional therapies. Although several studies have already been conducted, the functions and roles of CSCs in the development and progression of tumors remain to be elucidated. In this review article, we will clarify the fundamental knowledge of CSCs necessary for the understanding of CSCs and will outline so-far identified markers specific to liver CSCs and the pathological and therapeutic implications of CSCs in HCC.

Hepatoblastoma: current knowledge and promises from preclinical studies

The survival rate for patients with metastatic hepatoblastoma (HB) is steadily increased in the last thirty years from 27% to 79%. These achievements result from accurate risk stratification and effective chemotherapy and surgical care. However, patients with poor prognosis require more effective therapies. Recent years have witnessed new insights on the biology of HB, setting the stage for molecular classification and new targets of therapy. We review here the molecular pathology of HB, focusing on the driver genes involved in the process of oncogenesis and the identification of novel targets. We also address the role of in vivo models in elucidating the mechanisms of development of this disease and the pre-clinical phase of new treatment modalities.

Volasertib preclinical activity in high-risk hepatoblastoma

Relapsed and metastatic hepatoblastoma represents an unmet clinical need with limited chemotherapy treatment options. In a chemical screen, we identified volasertib as an agent with in vitro activity, inhibiting hepatoblastoma cell growth while sparing normal hepatocytes. Volasertib targets PLK1 and prevents the progression of mitosis, resulting in eventual cell death. PLK1 is overexpressed in hepatoblastoma biopsies relative to normal liver tissue. As a potential therapeutic strategy, we tested the combination of volasertib and the relapse-related hepatoblastoma chemotherapeutic irinotecan. We found both in vitro and in vivo efficacy of this combination, which may merit further preclinical investigation and exploration for a clinical trial concept.

Histological and immunohistochemical study of hepatoblastoma: correlation with tumour behaviour and survival

Background

Hepatoblastoma (HB) has different histological subtypes, with varying prognosis. Though the survival has drastically improved, subsets of patients are not responsive to therapy. Therefore, it becomes important to determine the factors which affect the behaviour of the tumour. This study was aimed to look at the histopathological subtypes and compare with immunohistochemical (IHC) expression of CK19, beta-catenin and EpCAM and survival.

Methods

This study included 55 cases of HB. IHC expression of CK19, beta-catenin and EpCAM were correlated with histological subtypes, tumour behaviour, response to chemotherapy and survival.

Results

Most common epithelial subtype was fetal (43.2%) and mixed epithelial (54.8%) in pre- and post-chemotherapy groups respectively. Microvascular invasion (MVI) was present in 14/33 resected tumours. CK19 expression was seen in 54.2% and 72.2% of embryonal subtype, nuclear beta-catenin expression in 48.7% and 57.1% and EpCAM in 100% and 82.1% of tumours in pre- and post-chemotherapy groups, respectively. Fetal subtype had a lesser chance of MVI, recurrence, metastasis and death. Beta-catenin expression was associated with lower event free survival (EFS) and EpCAM with ≥50% viable tumour following chemotherapy (P=0.04). Age at diagnosis ≤2 years, male sex, alpha-fetoprotein <10,000 IU/mL following chemotherapy, solitary tumour (P=0.001), size ≤5 cm, pretreatment extent of disease (PRETEXT) I&II, mitosis ≤2/10 high power fields (hpf), viable tumour <50% (P=0.04) and absent nuclear expression of beta-catenin, predicted a higher EFS rate.

Conclusions

Beta-catenin expression is associated with lower EFS and EpCAM expression with tumour viability. Multifocality and viable tumour ≥50% were significant factors predicting lower EFS. These factors should be included in the prognostication of HBs.

Tracking cellular and molecular changes in a species-specific manner during experimental tumor progression in vivo

Hepatoblastoma (HBL) is a pediatric liver cancer with defined molecular alterations driving its progression. Here, we describe an animal model for HBL on the chick chorioallantoic membrane (CAM), which recapitulates relevant features of HBL in patients. Expression of classic tumor-associated proteins such as β-catenin, EpCAM and CK19 was maintained in acini-like organized tumors on CAM, as was synthesis of AFP, a tumor marker used for monitoring patient response. RNA sequencing revealed an unexpected molecular evolution of HBL cells on the CAM, with significant deregulation of more than 6,000 genes including more than half of all HOX genes. Bioinformatic analysis distinguish between tumor cell-expressed genes and chick genes, thereby shedding new light on the complex interactions taking place during HBL progression. Importantly, human tumor suppressive ribosomal genes were downregulated after implantation, whereas mitochondrial genes encoding for anti-apoptotic peptides were strongly induced in vivo. Meprin-1α expression was increased during evolution of CAM tumors and confirmed by immunohistochemistry. Cisplatin, a commonly used chemotherapeutic agent for HBL, showed significant anti-tumoral effects. Our results broaden the understanding of the molecular adaptation process of human cancer cells to the microenvironment and might help to elaborate novel therapeutic concepts for the treatment of this pediatric liver tumor.

Liver Cancer: Molecular Characterization, Clonal Evolution and Cancer Stem Cells

Liver cancer is the second most common cause of cancer-related death. The major forms of primary liver cancer are hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). Both these tumors develop against a background of cirrhotic liver, non-alcoholic fatty liver disease, chronic liver damage and fibrosis. HCC is a heterogeneous disease which usually develops within liver cirrhosis related to various etiologies: hepatitis B virus (HBV) infection (frequent in Asia and Africa), hepatitis C virus (HCV), chronic alcohol abuse, or metabolic syndrome (frequent in Western countries). In cirrhosis, hepatocarcinogenesis is a multi-step process where pre-cancerous dysplastic macronodules transform progressively into HCC. The patterns of genomic alterations observed in these tumors were recently identified and were instrumental for the identification of potential targeted therapies that could improve patient care. Liver cancer stem cells are a small subset of undifferentiated liver tumor cells, responsible for cancer initiation, metastasis, relapse and chemoresistance, enriched and isolated according to immunophenotypic and functional properties: cell surface proteins (CD133, CD90, CD44, EpCAM, OV-6, CD13, CD24, DLK1, α2δ1, ICAM-1 and CD47); the functional markers corresponding to side population, high aldehyde dehydrogenase (ALDH) activity and autofluorescence. The identification and definition of liver cancer stem cells requires both immunophenotypic and functional properties.

Biomimetic strategies for targeted nanoparticle delivery

Nanoparticle‐based drug delivery and imaging platforms have become increasingly popular over the past several decades. Among different design parameters that can affect their performance, the incorporation of targeting functionality onto nanoparticle surfaces has been a widely studied subject. Targeted formulations have the ability to improve efficacy and function by positively modulating tissue localization. Many methods exist for creating targeted nanoformulations, including the use of custom biomolecules such as antibodies or aptamers. More recently, a great amount of focus has been placed on biomimetic targeting strategies that leverage targeting interactions found directly in nature. Such strategies, which have been painstakingly selected over time by the process of evolution to maximize functionality, oftentimes enable scientists to forgo the specialized discovery processes associated with many traditional ligands and help to accelerate development of novel nanoparticle formulations. In this review, we categorize and discuss in‐depth recent works in this growing field of bioinspired research.

Differentiation therapy of hepatocellular carcinoma by inhibiting the activity of AKT/GSK-3β/β-catenin axis and TGF-β induced EMT with sophocarpine

Hepatocellular carcinoma progression is thought to be driven by cancer stem cells (CSCs). No clinical trial has, as yet, shown convincing long-term disease free survival results for the majority of patients in HCC. So it is important to discover new anti-cancer agents. In our study, we chose sophocarpine, which is derived from the foxtail-like sophora herb, for its efficacy to inhibit HCC including CSCs and potential mechanism study. Our results show that sophocarpine could not only reduce HCC cell viability, eliminate HCC and reverse hepatoma cells malignant phenotype, but also reduce the ratio of CSCs and inhibit the sphere formation of CSCs in vitro. In vivo, sophocarpine significantly displayed antitumor effects in subcutaneous xenograft HCC models and orthotopic transplantation tumor models. Further studies showed that sophocarpine could exert anti-tumor effects partly via downregulating the activity of the cancer stem cell related pathways and inhibiting EMT induced by TGF-β.

Design and characterization of the tumor vaccine MGN1601, allogeneic fourfold gene-modified vaccine cells combined with a TLR-9 agonist

The tumor vaccine MGN1601 was designed and developed for treatment of metastatic renal cell carcinoma (mRCC). MGN1601 consists of a combination of fourfold gene-modified cells with the toll-like receptor 9 agonist dSLIM, a powerful connector of innate and adaptive immunity. Vaccine cells originate from a renal cell carcinoma cell line (grown from renal cell carcinoma tissue), express a variety of known tumor-associated antigens (TAA), and are gene modified to transiently express two co-stimulatory molecules, CD80 and CD154, and two cytokines, GM-CSF and IL-7, aimed to support immune response. Proof of concept of the designed vaccine was shown in mice: The murine homologue of the vaccine efficiently (100%) prevented tumor growth when used as prophylactic vaccine in a syngeneic setting. Use of the vaccine in a therapeutic setting showed complete response in 92% of mice as well as synergistic action and necessity of the components. In addition, specific cellular and humoral immune responses in mice were found when used in an allogeneic setting. Immune response to the vaccine was also shown in mRCC patients treated with MGN1601: Peptide array analysis revealed humoral CD4-based immune response to TAA expressed on vaccine cells, including survivin, cyclin D1, and stromelysin.

Trial watch: Tumor-targeting monoclonal antibodies for oncological indications

An expanding panel of monoclonal antibodies (mAbs) that specifically target malignant cells or intercept trophic factors delivered by the tumor stroma is now available for cancer therapy. These mAbs can exert direct antiproliferative/cytotoxic effects as they inhibit pro-survival signal transduction cascades or activate lethal receptors at the plasma membrane of cancer cells, they can opsonize neoplastic cells to initiate a tumor-targeting immune response, or they can be harnessed to specifically deliver toxins or radionuclides to transformed cells. As an indication of the success of this immunotherapeutic paradigm, international regulatory agencies approve new tumor-targeting mAbs for use in cancer patients every year. Moreover, the list of indications for previously licensed molecules is frequently expanded to other neoplastic disorders as the results of large, randomized clinical trials become available. Here, we discuss recent advances in the preclinical and clinical development of tumor-targeting mAbs for oncological indications.

Classification of current anticancer immunotherapies

During the past decades, anticancer immunotherapy has evolved from a promising therapeutic option to a robust clinical reality. Many immunotherapeutic regimens are now approved by the US Food and Drug Administration and the European Medicines Agency for use in cancer patients, and many others are being investigated as standalone therapeutic interventions or combined with conventional treatments in clinical studies. Immunotherapies may be subdivided into "passive" and "active" based on their ability to engage the host immune system against cancer. Since the anticancer activity of most passive immunotherapeutics (including tumor-targeting monoclonal antibodies) also relies on the host immune system, this classification does not properly reflect the complexity of the drug-host-tumor interaction. Alternatively, anticancer immunotherapeutics can be classified according to their antigen specificity. While some immunotherapies specifically target one (or a few) defined tumor-associated antigen(s), others operate in a relatively non-specific manner and boost natural or therapy-elicited anticancer immune responses of unknown and often broad specificity. Here, we propose a critical, integrated classification of anticancer immunotherapies and discuss the clinical relevance of these approaches.

Multidrug resistance and cancer stem cells in neuroblastoma and hepatoblastoma

Chemotherapy is one of the major modalities in treating cancers. However, its effectiveness is limited by the acquisition of multidrug resistance (MDR). Several mechanisms could explain the up-regulation of MDR genes/proteins in cancer after chemotherapy. It is known that cancer stem cells (CSCs) play a role as master regulators. Therefore, understanding the mechanisms that regulate some traits of CSCs may help design efficient strategies to overcome chemoresistance. Different CSC phenotypes have been identified, including those found in some pediatric malignancies. As solid tumors in children significantly differ from those observed in adults, this review aims at providing an overview of the mechanistic relationship between MDR and CSCs in common solid tumors, and, in particular, focuses on clinical as well as experimental evidence of the relations between CSCs and MDR in neuroblastoma and hepatoblastoma. Finally, some novel approaches, such as concomitant targeting of multiple key transcription factors governing the stemness of CSCs, as well as nanoparticle-based approaches will also be briefly addressed.