From the identification of actionable molecular targets to the generation of faithful neuroblastoma patient-derived preclinical models

BACKGROUND

Neuroblastoma (NB) represents the most frequent and aggressive form of extracranial solid tumor of infants. Although the overall survival of patients with NB has improved in the last years, more than 50% of high-risk patients still undergo a relapse. Thus, in the era of precision/personalized medicine, the need for high-risk NB patient-specific therapies is urgent.

METHODS

Within the PeRsonalizEd Medicine (PREME) program, patient-derived NB tumors and bone marrow (BM)-infiltrating NB cells, derived from either iliac crests or tumor bone lesions, underwent to histological and to flow cytometry immunophenotyping, respectively. BM samples containing a NB cells infiltration from 1 to 50 percent, underwent to a subsequent NB cells enrichment using immune-magnetic manipulation. Then, NB samples were used for the identification of actionable targets and for the generation of 3D/tumor-spheres and Patient-Derived Xenografts (PDX) and Cell PDX (CPDX) preclinical models.

RESULTS

Eighty-four percent of NB-patients showed potentially therapeutically targetable somatic alterations (including point mutations, copy number variations and mRNA over-expression). Sixty-six percent of samples showed alterations, graded as "very high priority", that are validated to be directly targetable by an approved drug or an investigational agent. A molecular targeted therapy was applied for four patients, while a genetic counseling was suggested to two patients having one pathogenic germline variant in known cancer predisposition genes. Out of eleven samples implanted in mice, five gave rise to (C)PDX, all preserved in a local PDX Bio-bank. Interestingly, comparing all molecular alterations and histological and immunophenotypic features among the original patient's tumors and PDX/CPDX up to second generation, a high grade of similarity was observed. Notably, also 3D models conserved immunophenotypic features and molecular alterations of the original tumors.

CONCLUSIONS

PREME confirms the possibility of identifying targetable genomic alterations in NB, indeed, a molecular targeted therapy was applied to four NB patients. PREME paves the way to the creation of clinically relevant repositories of faithful patient-derived (C)PDX and 3D models, on which testing precision, NB standard-of-care and experimental medicines.

Antitumor activity of the investigational B7-H3 antibody-drug conjugate, vobramitamab duocarmazine, in preclinical models of neuroblastoma

INTRODUCTION

B7-H3 is a potential target for pediatric cancers, including neuroblastoma (NB). Vobramitamab duocarmazine (also referred to as MGC018 and herein referred to as vobra duo) is an investigational duocarmycin-based antibody-drug conjugate (ADC) directed against the B7-H3 antigen. It is composed of an anti-B7-H3 humanized IgG1/kappa monoclonal antibody chemically conjugated through a cleavable valine-citrulline linker to a duocarmycin-hydroxybenzamide azaindole (vc-seco-DUBA). Vobra duo has shown preliminary clinical activity in B7-H3-expressing tumors.

METHODS

B7-H3 expression was evaluated by flow-cytometry in a panel of human NB cell lines. Cytotoxicity was evaluated in monolayer and in multicellular tumor spheroid (MCTS) models by the water-soluble tetrazolium salt,MTS, proliferation assay and Cell Titer Glo 3D cell viability assay, respectively. Apoptotic cell death was investigated by annexin V staining. Orthotopic, pseudometastatic, and resected mouse NB models were developed to mimic disease conditions related to primary tumor growth, metastases, and circulating tumor cells with minimal residual disease, respectively.

RESULTS

All human NB cell lines expressed cell surface B7-H3 in a unimodal fashion. Vobra duo was cytotoxic in a dose-dependent and time-dependent manner against all cell lines (IC50 range 5.1-53.9 ng/mL) and NB MCTS (IC50 range 17.8-364 ng/mL). Vobra duo was inactive against a murine NB cell line (NX-S2) that did not express human B7-H3; however, NX-S2 cells were killed in the presence of vobra duo when co-cultured with human B7-H3-expressing cells, demonstrating bystander activity. In orthotopic and pseudometastatic mouse models, weekly intravenous treatments with 1 mg/kg vobra duo for 3 weeks delayed tumor growth compared with animals treated with an irrelevant (anti-CD20) duocarmycin-ADC. Vobra duo treatment for 4 weeks further increased survival in both orthotopic and resected NB models. Vobra duo compared favorably to TOpotecan-TEMozolomide (TOTEM), the standard-of-care therapy for NB relapsed disease, with tumor relapse delayed or arrested by two or three repeated 4-week vobra duo treatments, respectively. Further increased survival was observed in mice treated with vobra duo in combination with TOTEM. Vobra duo treatment was not associated with body weight loss, hematological toxicity, or clinical chemistry abnormalities.

CONCLUSION

Vobra duo exerts relevant antitumor activity in preclinical B7-H3-expressing NB models and represents a potential candidate for clinical translation.

Abstract 3407: The italian personalized medicine program PREME for high-risk neuroblastoma

Background: In the era of precision medicine, the need for high-risk neuroblastoma (NB) patient-specific therapies is crucial.

Methods: From November 2018 to February 2021, the Italian PeRsonalizEd MEdicine (PREME) program has enrolled 18 NB affected patients. Tumors and bone marrow-infiltrating NB cells underwent to histological (selection panel: CD45, CD56, TH, PHOX-2B, S100) and to flow cytometry (selection panel: CD45, CD56, GD2, B7-H3) immunophenotyping, respectively. The biological material was then used for: 1) DNA extraction for subsequent DNAseq (Whole Exome Sequencing, 100X mean coverage, or Deep Targeted Gene Panel Sequencing, 1000x mean coverage, when the percentage of the neoplastic counterpart within the sample was over or down 60%, respectively); 2) RNA extraction for subsequent RNAseq (30 millions of reads per sample); 3) Development of primary NB cell culture (3D/tumor-spheres) and of Patient-Derived Xenografts (PDX) models in mice (both stored in local Bio-banks).

Results: 14 out of 18 patients (77.7%) had one or more potentially actionable somatic alterations in primary tumors. Among those, 4 had also one pathogenic germline variant in known cancer predisposition genes. In 11 of the 14 cases the Molecular Tumor Board identified molecular alterations potentially targetable by an approved or investigational agent, and 4 of those received the treatment. Out of 11 tumor samples implanted in mice, 5 gave rise to PDX, all preserved in a local PDX Bio-bank. Comparing all genomic variants of the 5 tumors with developed PDX samples up to second generation, we observed a high grade of similarity among primary tumors and subsequent PDX tumor models (Pearson coefficients>0.8). Considered the allele frequency distribution, a significant increase in the PDX tumor models at first generation (G1) (median=0.008) and second generations (G2) (median=0.038) with respect to the primary tumors (G0) (median=0.034) was observed. The validity and reproducibility of our PDX models was further demonstrated from high rates of conserved somatic variants at G1 compared to G0 tumors (mean=81.93%), at G2 compared to G1 (mean=84.04%) and at G2 compared to G0 tumors (mean=78.31%). Finally, we were able to identify all the potentially actionable genetic alterations of G0 tumors in the PDX generations G1 and G2. A high grade of similarity was confirmed when the histological, the immunophenotypic and the transcriptomic profiles among primary tumors and PDX generations were compared. Also, NB cells grown as 3D demonstrated good rates of conserved somatic variants, paving the way to the creation of a Bio-bank of patient-derived tumor-spheres. The development of a bioinformatics pipeline for RNAseq data analysis is ongoing.

Conclusions: Until now, PREME program has reported a large number of NB patient samples, which harbor targetable genomic alterations and has allowed the development of a Bio-banks to be used for translational research.

Citation Format: Mario Capasso, Chiara Brignole, Veronica Bensa, Vito Alessandro Lasorsa, Enrico Sebastiani, Sueva Cantalupo, Angela Rita Sementa, Katia Mazzocco, Barbara Cafferata, Valerio Gaetano Vellone, Michele Cilli, Enzo Calarco, Elena Giusto, Eleonora Ciampi, Patrizia Perri, Maria Valeria Corrias, Sanja Aveic, Doriana Fruci, Alessandro Quattrone, Annalisa Tondo, Roberto Luksch, Rossella Mura, Marco Rabusin, Francesco De Leonardis, Monica Cellini, Paola Coccia, Massimo Conte, Loredana Amoroso, Alberto Garaventa, Mirco Ponzoni, Fabio Pastorino. The italian personalized medicine program PREME for high-risk neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3407.

Therapeutic Targeting of ALK in Neuroblastoma: Experience of Italian Precision Medicine in Pediatric Oncology

Neuroblastoma (NB) is the most common extracranial solid tumor in childhood. Patients with relapsed/refractory disease have a poor prognosis, and additional therapeutic options are needed. Mutations and amplifications in the ALK (Anaplastic Lymphoma Kinase) gene constitute a key target for treatment. Our goal, within the Italian project of PeRsonalizEdMEdicine (PREME), was to evaluate the genomic status of patients with relapsed/refractory NB and to implement targeted therapies in those with targetable mutations. From November 2018 to November 2021, we performed Whole Exome Sequencing or Targeted Gene Panel Sequencing in relapsed/refractory NB patients in order to identify druggable variants. Activating mutations of ALK were identified in 8(28.57%) of 28 relapsed/refractory NB patients. The mutation p.F1174L was found in six patients, whereas p.R1275Q was found in one and the unknown mutation p.S104R in another. Three patients died before treatment could be started, while five patients received crizotinib: two in monotherapy (one with p.F1174L and the other with p.S104R) and three (with p.F1174L variant) in combination with chemotherapy. All treated patients showed a clinical improvement, and one had complete remission after two cycles of combined treatment. The most common treatment-related toxicities were hematological. ALK inhibitors may play an important role in the treatment of ALK-mutated NB patients.

Nucleolin expression has prognostic value in neuroblastoma patients

BACKGROUND

Neuroblastoma (NB) represents the most frequent form of extra-cranial solid tumour of infants, responsible for 15% of childhood cancer deaths. Nucleolin (NCL) prognostic value in NB was investigated.

METHODS

NCL protein expression was retrospectively evaluated in tumour samples of NB patients at diagnosis and after chemotherapy. NCL prognostic value at mRNA level was assessed in a cohort of 20 patients with stage 4 NB (qPCR20, n=20, discovery dataset) and in the MultiPlatform786 including 786 patients of all stages (validation dataset). Overall and event-free survival curves were plotted by Kaplan-Meier method and compared by log-rank test.

FINDINGS

NCL protein, down-modulated after chemotherapy in association with features of neuroblastic differentiation,resulted statistically significantly overexpressed in NB tumours and higher in stage 4 compared to stage 1,2,3 patients. In the stage 4 patients cohort qPCR20, patients with high NCLmRNA expression revealed a statisticallysignificant lower survival probability than those with low NCL expression (OS: HR 4.1 95%CI 1.2-13.8;p=0.0215[Log-rank test], EFS: HR 4.1 95%CI 1.2-14.0, p=0.0197[Log-rank test]). In the MultiPlatform786 (n=786), multivariate analysis suggested thatNCL expression has a statistically significant prognostic value even in the model adjusted for established prognostic markers. NCL expression significantly stratified also patients with >18 months and stage 4 tumour (OS: HR 1.8 95%CI 1.2-2.7, p=0.0009[Log-rank test]; EFS: HR 1.7 95%CI 1.1-2.5, p=0.002[Log-rank test]), patients with>18 months stage 4 with MYCN non amplified tumour[EFS: HR 2.3 95%CI 1.2-4.7, p=0.01[Log-rank test]), and patients with MYCN non amplified and MYC high [OS: HR 11.9 95%CI 2.3-62.4, p=0.003[Log-rank test]; EFS: HR 7.2 95%CI 1.6-33.4, p=0.01[Log-rank test]). A statistically significant correlation between NCL and MYCN, MYC, and TERT was found in independent datasets (MultiPlatform786 (n=786) and Agilent394 (n=394). Gene set enrichment analysis revealed a statisticallysignificant positive enrichment of MYC target genes and genes involved in telomerase maintenance.

INTERPRETATION

NCL is a novel and independent (adjusting for age, INSS stage, and MYCN status) prognostic marker for NB.

FUNDING

IMH-EuroNanoMed II-2015 and AIRC-IG.

Italian Precision Medicine in Pediatric Oncology: Moving beyond Actionable Alterations

Neuroblastoma (NB) is the most common extracranial solid tumor encountered in childhood. Although there has been significant improvement in the outcomes of patients with high-risk disease, the prognosis for patients with metastatic relapse or refractory disease is poor. Hence, the clinical integration of genome sequencing into standard clinical practice is necessary in order to develop personalized therapy for children with relapsed or refractory disease. The PeRsonalizEdMEdicine (PREME) project focuses on the design of innovative therapeutic strategies for patients suffering from relapsed NB. We performed whole exome sequencing (WES) of patient-matched tumor-normal samples to identify genetic variants amenable to precision medicine. Specifically, two patients were studied (First case: a three-year-old male with early relapsed NB; Second case: a 20-year-old male who relapsed 10 years after the first diagnosis of NB). Results were reviewed by a multi-disciplinary molecular tumor board (MTB) and clinical reports were issued to the ordering physician. WES revealed the mutation c.G320C in the CUL4A gene in case 1 and the mutation c.A484G in the PSMC2 gene in case 2. Both patients were treated according to these actionable alterations, with promising results. The effective treatment of NB is one of the main challenges in pediatric oncology. In the era of precision medicine, the need to design new therapeutic strategies for NB is fundamental. Our results demonstrate the feasibility of incorporating clinical WES into pediatric oncology practice.

Abstract 5069: Delivering docetaxel and curcumin via a nano-combination-therapy for modulating the progression of neuroblastoma

Introduction: Neuroblastoma (NB) is a form of extracranial tumor derived from the sympathetic nervous system that affects most often infants and young children. It is a very heterogeneous tumor with different levels of aggressiveness. Despite the multiple therapeutic strategies (i.e. aggressive chemotherapy, surgery, radiotherapy, immunotherapy), the outcome in advanced stages or recurrent diseases is negative. New strategies are needed to improve the therapeutic efficacy of existing drugs and reduce their toxicity. Nanotechnology represents a good tool for reaching this goal. Taken this in mind, the focus of this experimental work was to engineer polymeric biodegradable nanomedicines for co-delivering anti-inflammatory and chemotherapeutic molecules to NB malignant masses. More specifically, the work focused on the synthesis, physico-chemical and biopharmaceutical characterization, in vitro testing and in vivo validation of nanomedicines loaded with the cytotoxic drug Docetaxel (DTXL) and the natural anti-inflammatory compound, Curcumin (CURC).

Methods: Four configurations of Spherical Polymeric Nanoparticles (SPNs) - loaded with CURC (CURC-SPNs), loaded with DTXL (DTXL-SPNs), loaded with the combination thereof (CURC/DTXL-SPNs), and empty (SPNs) - were synthesized using an oil-in water emulsion/solvent evaporation technique. SPNs size, zeta potential, and polydispersity index (PDI) were measured by dynamic light scattering. The toxicity of SPNs was determined by an MTT assay on the human NB cell line SH-SY5Y. For in vivo efficacy and biodistribution experiments, homozygous CD1 nu/nu athymic female mice (4 to 6-weeks old) were orthotopically injected with SH-SY5Y cells in the left adrenal gland.

Results: Empty, DTXL-SPNs, CURC-SPNs, and CURC/DTXL-SPNs were characterized by a narrow size distribution (PdI < 0.15) with an average hydrodynamic diameter of about 185 nm. All the formulations showed a negative surface ζ-potential, associated with the carboxylate groups in the DSPE-PEG coating. A biphasic release profile was observed for all the 3 formulations, with almost 90% of the total drug mass released within the first 24 hours. In vivo results indicated that mice treated with CURC/DTXL -SPNs had a significant increase in life span as compared to untreated mice (control) (p=0.0002), mice treated with CURC-SPNs (p=0.0205), DTXL-SPNs (p=0.0391), and free DTXL (p=0.0054). Biodistribution experiments showed a 2% ID/g accumulation of the injected dose per tumor mass, regardless of the tumor development stage. This behavior is in agreement with results from a longitudinal Magnetic Resonance Imaging analysis of the malignant masses.

Conclusion: The obtained results would suggest that nanomedicines could effectively delivery two therapeutic molecules within the malignant mass and modulate its progression leading to a significant increase in overall survival.

Citation Format: Agnese Fragassi, Martina Di Francesco, Fabio Pastorino, Miguel Ferreira, Valentina Di Francesco, Anna Lisa Palange, Christian Celia, Luisa Di Marzio, Michele Cilli, Veronica Bensa, Mirco Ponzoni, Paolo Decuzzi. Delivering docetaxel and curcumin via a nano-combination-therapy for modulating the progression of neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5069.

Abstract 1276: Nucleolin has prognostic value in neuroblastoma patients

Background: Neuroblastoma (NB) represents the most frequent form of extracranial solid tumor of infants, responsible for 15% of childhood cancer deaths. Nucleolin (NCL) prognostic value in NB was here investigated.

Methods: NCL protein expression was evaluated in NB patients at diagnosis and after induction chemotherapy. NCL mRNA prognostic value was first assessed in a cohort of 20 stage M NB patients and confirmed in the MultiPlatform786 including 786 NB patients of all stages. Overall and event-free survival curves were plotted by Kaplan-Meier method and compared by log-rank test.

Findings: NCL protein resulted significantly overexpressed in NB tumors compared to the non tumoral counterpart, and higher in stage M compared to stage L patients. In the stage M cohort and in MultiPlatform786 dataset, patients with high NCL mRNA expression revealed a significant lower survival probability than those with low NCL expression. In MultiPlatform786 dataset, NCL mRNA expression was significantly higher in patients with age >18 months, in stage M and in MYCN amplified tumors than in patients with age ˂18 months and in stage L or MS and with MYCN non amplified tumors, respectively. Multivariate analysis suggested NCL has a significant prognostic value even in the model adjusted for established prognostic markers. NCL significantly stratified patients with age <18 and age >18, stage M, >18 months and stage M tumor, stages L or MS, and with MYCN not amplified. A significant correlation between NCL and MYCN, MYC, and TERT was found in two independent datasets. Gene set enrichment analysis revealed a significant positive enrichment of MYC target genes and genes involved in telomerase maintenance. NCL protein resulted down-modulated after chemotherapy, in association with morphological features of neuroblastic differentiation.

Interpretation: NCL is a novel and independent prognostic marker for NB.

Funding: IMH-EuroNanoMed II-2015 (ER-2015-2360441-Eranet) and AIRC IG n. 24397 to PF.

Citation Format: Davide Cangelosi, Chiara Brignole, Veronica Bensa, Roberto Tamma, Fabiana Malaguti, Barbara Carlini, Enzo Calarco, Patrizia Perri, Domenico Ribatti, Nuno A. Fonseca, Joao N. Moreira, Alessandra Eva, Loredana Amoroso, Massimo Conte, Alberto Garaventa, Angela R. Sementa, Maria V. Corrias, Mirco Ponzoni, Fabio Pastorino. Nucleolin has prognostic value in neuroblastoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1276.

Recent advances in the developmental origin of neuroblastoma: an overview

Neuroblastoma (NB) is a pediatric tumor that originates from neural crest-derived cells undergoing a defective differentiation due to genomic and epigenetic impairments. Therefore, NB may arise at any final site reached by migrating neural crest cells (NCCs) and their progeny, preferentially in the adrenal medulla or in the para-spinal ganglia.

NB shows a remarkable genetic heterogeneity including several chromosome/gene alterations and deregulated expression of key oncogenes that drive tumor initiation and promote disease progression.

NB substantially contributes to childhood cancer mortality, with a survival rate of only 40% for high-risk patients suffering chemo-resistant relapse. Hence, NB remains a challenge in pediatric oncology and the need of designing new therapies targeted to specific genetic/epigenetic alterations become imperative to improve the outcome of high-risk NB patients with refractory disease or chemo-resistant relapse.

In this review, we give a broad overview of the latest advances that have unraveled the developmental origin of NB and its complex epigenetic landscape.

Single-cell RNA sequencing with spatial transcriptomics and lineage tracing have identified the NCC progeny involved in normal development and in NB oncogenesis, revealing that adrenal NB cells transcriptionally resemble immature neuroblasts or their closest progenitors. The comparison of adrenal NB cells from patients classified into risk subgroups with normal sympatho-adrenal cells has highlighted that tumor phenotype severity correlates with neuroblast differentiation grade.

Transcriptional profiling of NB tumors has identified two cell identities that represent divergent differentiation states, i.e. undifferentiated mesenchymal (MES) and committed adrenergic (ADRN), able to interconvert by epigenetic reprogramming and to confer intra-tumoral heterogeneity and high plasticity to NB.

Chromatin immunoprecipitation sequencing has disclosed the existence of two super-enhancers and their associated transcription factor networks underlying MES and ADRN identities and controlling NB gene expression programs.

The discovery of NB-specific regulatory circuitries driving oncogenic transformation and maintaining the malignant state opens new perspectives on the design of innovative therapies targeted to the genetic and epigenetic determinants of NB. Remodeling the disrupted regulatory networks from a dysregulated expression, which blocks differentiation and enhances proliferation, toward a controlled expression that prompts the most differentiated state may represent a promising therapeutic strategy for NB.

The Olive Leaves Extract Has Anti-Tumor Effects against Neuroblastoma through Inhibition of Cell Proliferation and Induction of Apoptosis

Neuroblastoma (NB) is the most common extra-cranial solid tumor of pediatric age. The prognosis for high-risk NB patients remains poor, and new treatment strategies are desirable. The olive leaf extract (OLE) is constituted by phenolic compounds, whose health beneficial effects were reported. Here, the anti-tumor effects of OLE were investigated in vitro on a panel of NB cell lines in terms of (i) reduction of cell viability; (ii) inhibition of cell proliferation through cell cycle arrest; (iii) induction of apoptosis; and (iv) inhibition of cell migration. Furthermore, cytotoxicity experiments, by combining OLE with the chemotherapeutic topotecan, were also performed. OLE reduced the cell viability of NB cells in a time- and dose-dependent manner in 2D and 3D models. NB cells exposed to OLE underwent inhibition of cell proliferation, which was characterized by an arrest of the cell cycle progression in G0/G1 phase and by the accumulation of cells in the sub-G0 phase, which is peculiar of apoptotic death. This was confirmed by a dose-dependent increase of Annexin V+ cells (peculiar of apoptosis) and upregulation of caspases 3 and 7 protein levels. Moreover, OLE inhibited the migration of NB cells. Finally, the anti-tumor efficacy of the chemotherapeutic topotecan, in terms of cell viability reduction, was greatly enhanced by its combination with OLE. In conclusion, OLE has anti-tumor activity against NB by inhibiting cell proliferation and migration and by inducing apoptosis.

Cell surface Nucleolin represents a novel cellular target for neuroblastoma therapy

BACKGROUND

Neuroblastoma (NB) represents the most frequent and aggressive form of extracranial solid tumor of infants. Nucleolin (NCL) is a protein overexpressed and partially localized on the cell surface of tumor cells of adult cancers. Little is known about NCL and pediatric tumors and nothing is reported about cell surface NCL and NB.

METHODS

NB cell lines, Schwannian stroma-poor NB tumors and bone marrow (BM)-infiltrating NB cells were evaluated for the expression of cell surface NCL by Flow Cytometry, Imaging Flow Cytometry and Immunohistochemistry analyses. The cytotoxic activity of doxorubicin (DXR)-loaded nanocarriers decorated with the NCL-recognizing F3 peptide (T-DXR) was evaluated in terms of inhibition of NB cell proliferation and induction of cell death in vitro, whereas metastatic and orthotopic animal models of NB were used to examine their in vivo anti-tumor potential.

RESULTS

NB cell lines, NB tumor cells (including patient-derived and Patient-Derived Xenografts-PDX) and 70% of BM-infiltrating NB cells show cell surface NCL expression. NCL staining was evident on both tumor and endothelial tumor cells in NB xenografts. F3 peptide-targeted nanoparticles, co-localizing with cell surface NCL, strongly associates with NB cells showing selective tumor cell internalization. T-DXR result significantly more effective, in terms of inhibition of cell proliferation and reduction of cell viability in vitro, and in terms of delay of tumor growth in all NB animal model tested, when compared to both control mice and those treated with the untargeted formulation.

CONCLUSIONS

Our findings demonstrate that NCL could represent an innovative therapeutic cellular target for NB.

Bone Marrow Environment in Metastatic Neuroblastoma

The study of the interactions occurring in the BM environment has been facilitated by the peculiar nature of metastatic NB. In fact: (i) metastases are present at diagnosis; (ii) metastases are confined in a very specific tissue, the BM, suggestive of a strong attraction and possibility of survival; (iii) differently from adult cancers, NB metastases are available because the diagnostic procedures require morphological examination of BM; (iv) NB metastatic cells express surface antigens that allow enrichment of NB metastatic cells by immune-magnetic separation; and (v) patients with localized disease represent an internal control to discriminate specific alterations occurring in the metastatic niche from generic alterations determined by the neoplastic growth at the primary site. Here, we first review the information regarding the features of BM-infiltrating NB cells. Then, we focus on the alterations found in the BM of children with metastatic NB as compared to healthy children and children with localized NB. Specifically, information regarding all the BM cell populations and their sub-sets will be first examined in the context of BM microenvironment in metastatic NB. In the last part, the information regarding the soluble factors will be presented.