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.

An integrated approach to the evaluation of patients with asymptomatic or minimally symptomatic hyperCKemia.

INTRODUCTION/AIMS: Currently, there are no straightforward guidelines for the clinical and diagnostic management of hyperCKemia, a frequent and nonspecific presentation in muscle diseases. Therefore, we aimed to describe our diagnostic workflow for evaluating patients with this condition. METHODS: We selected 83 asymptomatic or minimally symptomatic patients with persistent hyperCKemia for participation in this Italian multicenter study. Patients with facial involvement and distal or congenital myopathies were excluded, as were patients with suspected inflammatory myopathies or predominant respiratory or cardiac involvement. All patients underwent a neurological examination and nerve conduction and electromyography studies. The first step of the investigation included a screening for Pompe disease. We then evaluated the patients for myotonic dystrophy type II-related CCTG expansion and excluded patients with copy number variations in the DMD gene. Subsequently, the undiagnosed patients were investigated using a target gene panel that included 20 genes associated with isolated hyperCKemia. RESULTS: Using this approach, we established a definitive diagnosis in one third of the patients. The detection rate was higher in patients with severe hyperCKemia and abnormal electromyographic findings. DISCUSSION: We have described our diagnostic workflow for isolated hyperCKemia, which is based on electrodiagnostic data, biochemical screening, and first-line genetic investigations, followed by successive targeted sequencing panels. Both clinical signs and electromyographic abnormalities are associated with increased diagnostic yields.

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.

Clinical and Genetic Features in Patients With Reflex Bathing Epilepsy.

OBJECTIVE: To describe the clinical and genetic findings in a cohort of individuals with bathing epilepsy, a rare form of reflex epilepsy. METHODS: We investigated by Sanger and targeted resequencing the SYN1 gene in 12 individuals from 10 different families presenting with seizures triggered primarily by bathing or showering. An additional 12 individuals with hot-water epilepsy were also screened. RESULTS: In all families with bathing epilepsy, we identified 8 distinct pathogenic or likely pathogenic variants and 2 variants of unknown significance in SYN1, 9 of which are novel. Conversely, none of the individuals with hot-water epilepsy displayed SYN1 variants. In mutated individuals, seizures were typically triggered by showering or bathing regardless of the water temperature. Additional triggers included fingernail clipping, haircutting, or watching someone take a shower. Unprovoked seizures and a variable degree of developmental delay were also common. CONCLUSION: Bathing epilepsy is genetically distinct reflex epilepsy caused mainly by SYN1 mutations.

Targeted re-sequencing in malformations of cortical development: genotype-phenotype correlations.

PURPOSE: Malformations of cortical development (MCD) are a phenotypically and genetically heterogeneous group of disorders, for which the diagnostic rate of genetic testing in a clinical setting remains to be clarified. In this study we aimed to assess the diagnostic rate of germline and pathogenic variants using a custom panel in a heterogeneous group of subjects with MCD and explore genotype-phenotype correlations. METHODS: A total of 84 subjects with different MCD were enrolled. Genomic DNA was isolated from peripheral blood. Fifty-nine tartget genes were assessed using a custom next-generation sequencing (NGS) panel. RESULTS: Genetic causes were identified in one-fourth of our cohort (21.4 %). Overall, we identified 19 pathogenic or likely pathogenic single-nucleotide variants in 11 genes among 18 subjects, including PAFAH1B1 (LIS1) (n = 3), TUBA1A (n = 3), DYNC1H1 (n = 3), ACTG1 (n = 2), TUBB2B (n = 1), TUBB3 (n = 1), DCX (n = 1), FLNA (n = 1), LAMA2 (n = 1), POMGNT2 (n = 1) and VLDLR (n = 1). The diagnostic yield was higher in patients with lissencephaly/pachygyria (60 %) (p = 0.001), cobblestone malformation (50 %), and subcortical band heterotopia (SBH) (40 %). Furthermore, five out of six subjects with suspect tubulinopathies on imaging harboured pathogenic variants in tubulin genes. Overall, germline pathogenic variants were more likely to be identified if MCD were diffuse (p = 0.002) and associated with other central nervous system malformations (p = 0.029). Moderate to severe intellectual disability was also more commonly associated with pathogenic variants (p = 0.044). CONCLUSION: Customized gene panels may support the diagnostic work-up for some specific MCD, especially when these are diffuse, bilateral and associated with other brain malformations.

Exosomal microRNAs from Longitudinal Liquid Biopsies for the Prediction of Response to Induction Chemotherapy in High-Risk Neuroblastoma Patients: A Proof of Concept SIOPEN Study.

Despite intensive treatment, 50% of children with high-risk neuroblastoma (HR-NB) succumb to their disease. Progression through current trials evaluating the efficacy of new treatments for children with HR disease usually depends on an inadequate response to induction chemotherapy, assessed using imaging modalities. In this study, we sought to identify circulating biomarkers that might be detected in a simple blood sample to predict patient response to induction chemotherapy. Since exosomes released by tumor cells can drive tumor growth and chemoresistance, we tested the hypothesis that exosomal microRNA (exo-miRNAs) in blood might predict response to induction chemotherapy. The exo-miRNAs expression profile in plasma samples collected from children treated in HR-NBL-1/SIOPEN before and after induction chemotherapy was compared to identify a three exo-miRs signature that could discriminate between poor and good responders. Exo-miRNAs expression also provided a chemoresistance index predicting the good or poor prognosis of HR-NB patients.

Soluble HLA-G and HLA-E Levels in Bone Marrow Plasma Samples Are Related to Disease Stage in Neuroblastoma Patients.

The role of nonclassical HLA-class Ib molecules HLA-G and HLA-E in the progression of Neuroblastoma (NB), the most common pediatric extracranial solid tumor, has been characterized in the last years. Since BM infiltration by NB cells is an adverse prognostic factor, we have here analyzed for the first time the concentration of soluble (s)HLA-G and HLA-E in bone marrow (BM) plasma samples from NB patients at diagnosis and healthy donors. sHLA-G and sHLA-E are present in BM plasma samples, and their levels were similar between NB patients and controls, thus suggesting that these molecules are physiologically released by resident or stromal BM cell populations. This hypothesis was supported by the finding that sHLA-G and sHLA-E levels did not correlate with BM infiltration and other adverse prognostic factors (MYCN amplification and age at diagnosis). In contrast, BM plasma levels of both molecules were higher in patients with metastatic disease than in patients with localized NB, thus suggesting that concentration of these molecules might be correlated with disease progression. The prognostic role of sHLA-G and sHLA-E concentration in the BM plasma for NB patients will be evaluated in future studies, by analyzing the clinical outcome of the same NB patients at follow-up.

CD4+CD25hiCD127- Treg and CD4+CD45R0+CD49b+LAG3+ Tr1 cells in bone marrow and peripheral blood samples from children with neuroblastoma.

Metastatic spread in the bone marrow (BM) at diagnosis is the worst prognostic factor for neuroblastoma (NB) patients. Here, we analyzed the presence of two immunosuppressive cell subsets, CD4+CD25hiCD127- regulatory T (Treg) cells and CD4+CD45R0+CD49b+LAG3+ type 1 regulatory (Tr1) cells, in BM and peripheral blood (PB) samples from NB patients and controls. Frequency of both regulatory cell subsets was lower in BM and PB samples from NB patients than in respective healthy controls. No correlation was found between the frequency of Treg and Tr1 cells and prognostic factors at diagnosis, such as age and stage. Only MYCN amplification correlated to a higher number of Treg in BM and of Tr1 in PB. These findings suggested an altered trafficking of regulatory T cells in NB, but delineated a limited role of these subsets in BM microenvironment and/or periphery in NB. These observations should be considered designing immunotherapeutic approaches for metastatic NB.

Expression of FOXP3, CD14, and ARG1 in Neuroblastoma Tumor Tissue from High-Risk Patients Predicts Event-Free and Overall Survival.

The prognosis of children with metastatic neuroblastoma (NB) > 18 months at diagnosis is dismal. Since the immune status of the tumor microenvironment could play a role in the history of disease, we evaluated the expression of CD45, CD14, ARG1, CD163, CD4, FOXP3, Perforin-1 (PRF1), Granzyme B (GRMB), and IL-10 mRNAs in primary tumors at diagnosis from children with metastatic NB and tested whether the transcript levels are significantly associated to event-free and overall survival (EFS and OS, resp.). Children with high expression of CD14, ARG1 and FOXP3 mRNA in their primary tumors had significantly better EFS. Elevated expression of CD14, and FOXP3 mRNA was significantly associated to better OS. CD14 mRNA expression levels significantly correlated to all markers, with the exception of CD4. Strong positive correlations were found between PRF1 and CD163, as well as between PFR1 and FOXP3. It is worth noting that the combination of high levels of CD14, FOXP3, and ARG1 mRNAs identified a small group of patients with excellent EFS and OS, whereas low levels of CD14 were sufficient to identify patients with dismal survival. Thus, the immune status of the primary tumors of high-risk NB patients may influence the natural history of this pediatric cancer.

IL-10 and ARG-1 concentrations in bone marrow and peripheral blood of metastatic neuroblastoma patients do not associate with clinical outcome.

The expression of the immunosuppressive molecules IL-10 and arginase 1 (ARG-1), and of FOXP3 and CD163, as markers of regulatory T cells (Treg) and macrophages, respectively, was evaluated in bone marrow (BM) and peripheral blood (PB) samples collected at diagnosis from patients with metastatic neuroblastoma (NB). IL-10 and ARG-1 plasma concentrations were measured and the association of each parameter with patients' outcome was tested. The percentages of immunosuppressive Treg and type-1 regulatory (Tr1) cells were also determined. In both BM and PB samples, IL-10 mRNA expression was higher in metastatic NB patients than in controls. IL-10 plasma concentration was higher in patients with NB regardless of stage. Neither IL-10 expression nor IL-10 plasma concentration significantly associated with patient survival. In PB samples from metastatic NB patients, ARG-1 and CD163 expression was higher than in controls but their expression did not associate with survival. Moreover, ARG-1 plasma concentration was lower than in controls, and no association with patient outcome was found. Finally, in metastatic NB patients, the percentage of circulating Treg was higher than in controls, whereas that of Tr1 cells was lower. In conclusion, although IL-10 concentration and Treg percentage were increased, their contribution to the natural history of metastatic NB appears uncertain.

Deregulation of focal adhesion pathway mediated by miR-659-3p is implicated in bone marrow infiltration of stage M neuroblastoma patients.

To get insights on the metastatic process of human neuroblastoma (NB), the miRNA expression profile of bone marrow (BM)-infiltrating cells has been determined and compared to that of primary tumors.Twenty-two BM-infiltrating cells, 22 primary tumors, and 4 paired samples from patients with metastatic NB aged > 12 months were analyzed for the expression of 670 miRNAs by stem-loop RT-qPCR. The miRNAs whose expression was significantly different were subjected to selection criteria, and 20 selected miRNAs were tested in 10 additional BM-infiltrating cells and primary tumors. Among the miRNAs confirmed to be differentially expressed, miR-659-3p was further analyzed. Transfection of miR-659-3p mimic and inhibitor demonstrated the specific suppression and over-expression, respectively, of the miR-659-3p target gene CNOT1, a regulator of transcription of genes containing AU-rich element (ARE) sequence. Among the ARE-containing genes, miR-659-3p mimic and inhibitor specifically modified the expression of AKT3, BCL2, CYR61 and THSB2, belonging to the focal adhesion pathway. Most importantly, in BM-infiltrating cells CNOT1 expression was significantly higher, and that of AKT3, BCL2, THSB2 and CYR61 was significantly lower than in primary tumors. Thus, our study suggests a role of the focal adhesion pathway, regulated by miR-659-3p through CNOT1, in the human NB metastatic process.

Multiple target molecular monitoring of bone marrow and peripheral blood samples from patients with localized neuroblastoma and healthy donors.

BACKGROUND: Multiple target molecular monitoring of minimal residual disease in neuroblastoma (NB) patients may increase sensitivity and overcome tumor heterogeneity. However, multiple target analysis is costly and time consuming, thus improvement with respect to single target monitoring needs to be achieved. PROCEDURES: Italian patients with localized NB were evaluated at diagnosis for TH, GD2-s, DDC, DCX, ELAV-4, STX, and Phox2b mRNA expressions. Patients with metastatic NB were tested as positive controls, together with NB primary tumors and cell lines, while healthy donors were tested as negative controls. RESULTS: All NB-related markers but Phox2b were expressed in healthy donors, and in a high percentage of patients with localized NB without association with clinical events. The introduction of cut-off levels increased marker specificity, although the percentage of positive results was only slightly modified. While TH positivity in PB samples significantly associated with a worse prognosis, a paradox association was found for GD2-s mRNA expression. No correlation and agreement between quantitative and qualitative results obtained with the two assays were found. In the set of samples tested for all markers, no pattern of expression was found to be associated with a specific clinical situation. CONCLUSION: These findings suggest that positive molecular results may not reflect the presence of disease, and that correlation among different markers is small in condition of low tumor burden. Thus, to reduce cost and amount of precious samples, in addition to TH, whose prognostic value was confirmed, only Phox2b warrants further evaluation in multi-center, prospective studies for high risk patients.

Serum levels of cytoplasmic melanoma-associated antigen at diagnosis may predict clinical relapse in neuroblastoma patients.

The high molecular weight melanoma-associated antigen (HMW-MAA) and the cytoplasmic melanoma-associated antigen (cyt-MAA/LGALS3BP) are expressed in melanoma. Their serum levels are increased in melanoma patients and correlate with clinical outcome. We investigated whether these molecules can serve as prognostic markers for neuroblastoma (NB) patients. Expression of cyt-MAA and HMW-MAA was evaluated by flow cytometry in NB cell lines, patients' neuroblasts ((FI)-NB), and short-term cultures of these latter cells (cNB). LGALS3BP gene expression was evaluated by RT-qPCR on (FI)-NB, cNB, and primary tumor specimens. Soluble HMW-MAA and cyt-MAA were tested by ELISA. Cyt-MAA and HMW-MAA were expressed in NB cell lines, cNB, and (FI)-NB samples. LGALS3BP gene expression was higher in primary tumors and cNB than in (FI)-NB samples. Soluble cyt-MAA, but not HMW-MAA, was detected in NB cell lines and cNBs supernatants. NB patients' serum levels of both antigens were higher than those of the healthy children. High cyt-MAA serum levels at diagnosis associated with higher incidence of relapse, independently from other known risk factors. In conclusion, both HMW-MAA and cyt-MAA antigens, and LGALS3BP gene, were expressed by NB cell lines and patients' neuroblasts, and both antigens' serum levels were increased in NB patients. Elevated serum levels of cyt-MAA at diagnosis correlated with relapse, supporting that cyt-MAA may serve as early serological biomarker to individuate patients at higher risk of relapse that may require a more careful follow-up, after being validated in a larger cohort of patients at different time-points during follow-up. Given its immunogenicity, cyt-MAA may also be a potential target for NB immunotherapy.

Neuroblastoma and bone metastases: clinical significance and prognostic value of Dickkopf 1 plasma levels.

The critical role of the Wnt pathway inhibition in sustaining the onset of bone lesions has been demonstrated in a variety of bone diseases and tumors, and it has been associated with cancer aggressiveness. We have previously demonstrated that neuroblastoma cells express Dickkopf 1 (Dkk1), an inhibitor of the canonical Wnt pathway which prevents the differentiation of bone-forming cells. Since Dkk1 is a secreted factor, it could have potential clinical application as tumor marker for detecting bone metastasis and monitoring of disease. In this study, we investigated the diagnostic and prognostic value of Dkk1 plasma levels in 92 children affected by neuroblastoma, including 32 with bone metastases. Fifty-seven children hospitalized for minor surgical problems served as control group. Circulating levels of Dkk1 were higher in healthy children than in normal adults and were comparable to those found in adult patients with aggressive tumors. No significant differences were found between neuroblastoma patients and controls and between patients with and without bone metastases. However, when only patients with metastatic neuroblastoma were considered, the highest Dkk1 levels were detected in patients that poorly responded to induction chemotherapy and in subjects with unamplified MYCN and three or more different metastatic sites. The 'Receiver Operating Characteristic' curve enabled us to identify a threshold value to distinguish patients who were unresponsive to induction treatment. The relationship between Dkk1 and drug resistance was supported by in vitro experiments, since an increased sensitivity to doxorubicin was found in neuroblastoma cells releasing low Dkk1 levels, either constitutively or experimentally following the treatment with specific siRNA. In conclusion, Dkk1 is released by neuroblastoma cells and is able to affect the balance between osteoblastogenesis and osteoclastogenesis, thus favoring the onset of osteolytic metastases. Nevertheless, Dkk1 plasma levels do not allow the detection of bone lesions in neuroblastoma but seem to have a predictive value with regard to the severity and the prognosis of the disease in a subset of patients with metastatic tumor. New knowledge on the biological role of Dkk1 in driving the natural history of neuroblastoma has to be further investigated and could help to establish specific therapeutic strategies able to target key factors of tumor progression.

Detection of cell-free RNA in children with neuroblastoma and comparison with that of whole blood cell RNA.

BACKGROUND: Since there is no validated assay to monitor disease in children with neuroblastoma (NB), we tested whether NB specific cell-free RNA could be detected in their plasma samples. Moreover, with the aim of reducing patients' discomfort, we compared this assay to a recently standardized procedure that uses a larger amount of whole blood. PROCEDURES: Using conditions that excluded RNA recovery from contaminating tumor cells, the total amount of cell-free RNA present in healthy children and patients with NB was quantified. Expression of tyrosine hydroxylase (TH) was assayed by quantitative RT-PCR. RESULTS: In patients with NB the amount of cell-free RNA was higher than in healthy children. However, it was less and more degraded than in healthy adults. The median amount of cell-free RNA that was reverse transcribed, measured through the use of standard curves for reference genes, was 0.03 (range 0-30) pg of input RNA, that is, always less than 1/10,000 of that reverse transcribed from total RNA extracted from whole cells. Despite the presence of disease and the positive results obtained with RNA extracted from peripheral blood cells, few cell-free RNA samples tested positive by the TH assay. Similar results were obtained also with TH primers specifically designed to amplify 50 bp RNA fragments. CONCLUSION: These findings suggest that for monitoring disease status detection of cell-free tumor-specific RNAs in patients with NB is not a reliable alternative to whole cell RNA.

Transient depletion of CD4(+) T cells augments IL-21-based immunotherapy of disseminated neuroblastoma in syngeneic mice.

IL-21 is a member of the IL-2 cytokine family, produced by CD4+ T cells. We previously showed that immunotherapy (IT) with IL-21-transduced neuroblastoma cells (Neuro2a/IL-21) cured 33% of syngeneic mice bearing systemic NB. Here, we studied whether the removal of Treg cells could potentiate the therapeutic efficacy of Neuro2a/IL-21 vaccine. The administration of anti-CD25 mAb, which targets Treg cells, slightly potentiated the effect of vaccine IT (50% cure rate), but anti-CD4 mAb had a more potent effect leading to 80% cure rate. Anti-CD25 mAb, indeed, only partially depleted CD4+CD25+FoxP3+ Treg cells, whereas anti-CD4 mAb was more effective in this respect, leading to 90% depletion of Treg cells. In mice receiving vaccine+anti-CD4 mAb, which developed systemic immunity to NB, CD4+ T cells counts completely recovered in 90 days. Depletion of CD8+ T cells abrogated the effect of the combined IT, indicating a predominant role of these cells in driving the immune response. In addition, CD8+ T cells from cured mice coinjected with Neuro2a/parental cells (pc) in NOD-SCID mice completely inhibited tumor growth. Spleen cells from mice receiving Neuro2a/IL-21 vaccination showed increased expression of IFN-alpha2, -beta1 and -gamma mRNA. Moreover, mice receiving vaccine therapy alone or vaccine+anti-CD4 mAb showed increased IFN-gamma serum levels and IFN-gamma-producing CD8+ T cells were found in spleen cells. In conclusion, anti-CD4 mAb potentiated IL-21-based IT by removing Treg cells and/or their precursors and other potentially immune-suppressive CD4+ cell subsets, thus allowing the development of an IL-21-driven CD8+ T cell response, which mediates NB rejection.

Immunotherapy of neuroblastoma by an Interleukin-21-secreting cell vaccine involves survivin as antigen.

AIM: IL-21 is the most recently identified member of the IL-2 cytokine family. Here we studied the therapeutic efficacy of IL-21-gene-modified cells (Neuro2a/IL-21) in a syngeneic metastatic neuroblastoma (NB) model. MATERIALS AND METHODS: Neuro2a/IL-21 cells were tested as subcutaneous (sc) vaccine both in prophylactic and therapeutic settings. Depletion studies, cytotoxicity assay and immunohistochemical analyses were carried out to evaluate the mechanisms involved in tumor rejection. RESULTS: When injected sc in syngeneic A/J mice viable Neuro2a/IL-21 cells were rejected and induced resistance to a subsequent iv challenge with Neuro2a parental cells (Neuro2a/pc), suggesting the involvement of an immune response. More importantly, in mice bearing Neuro2a/pc micrometastases, a single sc injection of Neuro2a/IL-21 cells significantly increased the mean tumor-free survival of treated animals (43 vs. 22 days) and cured 14% of them. The administration of two or three doses of Neuro2a/IL-21 cell vaccine further increased the mean survival time to 54 and 75 days, and the cure rate to 27 and 33%, respectively, whereas the use of unmodified Neuro2a or mock-transfected cells had no effect. In vivo cell subset depletion and a Winn-assay indicated the involvement of CD8 + CTLs. Immunohistochemical analysis indicated a reduction of CD31+ and VEGFR2+ microvessels in late metastases from therapeutically vaccinated mice. A role of survivin as antigen was suggested by in vitro assays using survivin-synthetic CTL-epitopes. CONCLUSIONS: Our present data indicate that IL-21-secreting NB cells are effective as therapeutic vaccine in mice bearing metastatic NB, through a specific CTL response involving survivin as antigen, and suggest a potential interest for IL-21 in NB immuno-gene therapy.

Peripheral blood stem cell tumor cell contamination and survival of neuroblastoma patients.

PURPOSE: Contribution of peripheral blood stem cell (PBSC) contaminating tumor cells to subsequent relapse and overall survival of neuroblastoma patients remains controversial. EXPERIMENTAL DESIGN: Neuroblastoma cell contamination of 27 PBSC harvests from stage IV neuroblastoma patients was assessed by quantitative RT-PCR for both tyrosine hydroxylase (TH) and GD2 synthase (GD2-s). The effect of PBSC contamination on survival was then analyzed. RESULTS: Seven PBSC tested negative for both markers; 19 were positive for GD2-s, 6 for TH, with 5 positive for both. Survival of the 20 patients with positive PBSC did not differ from that of the patients with negative PBSC (log-rank test, P = 0.134 and 0.218 for event-free survival and overall survival, respectively). By considering the TH and GD2-s results independently, a borderline (P = 0.053) negative effect on event-free survival was observed in patients reinfused with GD2-s-positive PBSC. When the status at transplant was taken into account, only the event-free survival of the patients rescued when in complete remission with GD2-s-negative PBSC was better, although not significantly, than that of patients infused with GD2-s-positive PBSC. CONCLUSIONS: Our results obtained in a small cohort of homogeneously treated stage IV patients suggest that patient survival is not affected by PBSC contamination with the exception of a borderline negative effect on event-free survival in patients rescued when in complete remission.