Mesenchymal and adrenergic cell lineage states in neuroblastoma possess distinct immunogenic phenotypes

Novel miRNA-inducing drugs enable differentiation of retinoic acid-resistant neuroblastoma cells

Tumor cell heterogeneity in neuroblastoma, a pediatric cancer arising from neural crest-derived progenitor cells, poses a significant clinical challenge. In particular, unlike adrenergic (ADRN) neuroblastoma cells, mesenchymal (MES) cells are resistant to chemotherapy and retinoid therapy and thereby significantly contribute to relapses and treatment failures. Previous research suggested that overexpression or activation of miR-124, a neurogenic microRNA with tumor suppressor activity, can induce the differentiation of retinoic acid-resistant neuroblastoma cells. Leveraging our established screen for miRNA modulatory small molecules, we validated PP121, a dual inhibitor of tyrosine and phosphoinositide kinases, as a robust inducer of miR-124. A combination of PP121 and miR-132-inducing bufalin synergistically arrests proliferation, induces differentiation, and prolongs the survival of differentiated MES SK-N-AS cells for 8 weeks. RNA- seq and deconvolution analyses revealed a collapse of the ADRN core regulatory circuitry (CRC) and the emergence of novel CRCs associated with chromaffin cells and Schwann cell precursors. Using a similar protocol, we differentiated and maintained other MES neuroblastoma, as well as glioblastoma cells, over 16 weeks. In conclusion, our novel protocol suggests a promising treatment for therapy-resistant cancers of the nervous system. Moreover, these long-lived, differentiated cells provide valuable models for studying mechanisms underlying differentiation, maturation, and senescence.

A potassium-chloride co-transporter with altered genome architecture functions as a suppressor in glioma

Gliomas, the most lethal tumours in brain, have a poor prognosis despite accepting standard treatment. Limited benefits from current therapies can be attributed to genetic, epigenetic and microenvironmental cues that affect cell programming and drive tumour heterogeneity. Through the analysis of Hi-C data, we identified a potassium-chloride co-transporter SLC12A5 associated with disrupted topologically associating domain which was downregulated in tumour tissues. Multiple independent glioma cohorts were included to analyse the characterization of SLC12A5 and found it was significantly associated with pathological features, prognostic value, genomic alterations, transcriptional landscape and drug response. We constructed two SLC12A5 overexpression cell lines to verify the function of SLC12A5 that suppressed tumour cell proliferation and migration in vitro. In addition, SLC12A5 was also positively associated with GABAA receptor activity and negatively associated with pro-tumour immune signatures and immunotherapy response. Collectively, our study provides a comprehensive characterization of SLC12A5 in glioma and supports SLC12A5 as a potential suppressor of disease progression.

Identification of MYCN non-amplified neuroblastoma subgroups points towards molecular signatures for precision prognosis and therapy stratification

BACKGROUND

Despite the extensive study of MYCN-amplified neuroblastomas, there is a significant unmet clinical need in MYCN non-amplified cases. In particular, the extent of heterogeneity within the MYCN non-amplified population is unknown.

METHODS

A total of 1566 samples from 16 datasets were identified in Gene Expression Omnibus (GEO) and ArrayExpress. Characterisation of the subtypes was analysed by ConsensusClusterPlus. Independent predictors for subgrouping were constructed from the single sample predictor based on the multiclassPairs package. Findings were verified using immunohistochemistry and CIBERSORTx analysis.

RESULTS

We demonstrate that MYCN non-amplified neuroblastomas are heterogeneous and can be classified into 3 subgroups based on their transcriptional signatures. Within these groups, subgroup_2 has the worst prognosis and this group shows a 'MYCN' signature that is potentially induced by the overexpression of Aurora Kinase A (AURKA); whilst subgroup_3 is characterised by an 'inflamed' gene signature. The clinical implications of this subtype classification are significant, as each subtype demonstrates a unique prognosis and vulnerability to investigational therapies. A total of 420 genes were identified as independent subgroup predictors with average balanced accuracy of 0.93 and 0.84 for train and test datasets, respectively.

CONCLUSION

We propose that transcriptional subtyping may enhance precision prognosis and therapy stratification for patients with MYCN non-amplified neuroblastomas.

Transition to a mesenchymal state in neuroblastoma may be characterized by a high expression of GD2 and by the acquisition of immune escape from NK cells

Background

Neuroblastoma (NB) is characterized by both adrenergic (ADRN) and undifferentiated mesenchymal (MES) subsets. The ganglioside sialic acid-containing glycosphingolipid (GD2) is widely overexpressed on tumors of neuroectodermal origin promoting malignant phenotypes. MES cells are greatly enriched in post-therapy and relapsing tumors and are characterized by decreased expression of GD2. This event may cause failure of GD2-based immunotherapy. NK cells represent a key innate cell subset able to efficiently kill tumors. However, the tumor microenvironment (TME) that includes tumor cells and tumor-associated (TA) cells could inhibit their effector function.

Methods

We studied eight NB primary cultures that, in comparison with commercial cell lines, more faithfully reflect the tumor cell characteristics. We studied four primary NB-MES cell cultures and two pairs of MES/ADRN (691 and 717) primary cultures, derived from the same patient. In particular, in the six human NB primary cultures, we assessed their phenotype, the expression of GD2, and the enzymes that control its expression, as well as their interactions with NK cells, using flow cytometry, RT-qPCR, and cytotoxicity assays.

Results

We identified mature (CD105+/CD133-) and undifferentiated (CD133+/CD105-) NB subsets that express high levels of the MES transcripts WWTR1 and SIX4. In addition, undifferentiated MES cells display a strong resistance to NK-mediated killing. On the contrary, mature NB-MES cells display an intermediate resistance to NK-mediated killing and exhibit some immunomodulatory capacities on NK cells but do not inhibit their cytolytic activity. Notably, independent from their undifferentiated or mature phenotype, NB-MES cells express GD2 that can be further upregulated in undifferentiated NB-MES cells upon co-culture with NK cells, leading to the generation of mature mesenchymal GD2bright neuroblasts. Concerning 691 and 717, they show high levels of GD2 and resistance to NK cell-mediated killing that can be overcome by the administration of dinutuximab beta, the anti-GD2 monoclonal antibody applied in the clinic.

Conclusions

NB is a heterogeneous tumor representing a further hurdle in NB immunotherapy. However, different from what was reported with NB commercial cells and independent of their MES/ADRN phenotype, the expression of GD2 and its displayed sensitivity to anti-GD2 mAb ADCC indicated the possible effectiveness of anti-GD2 immunotherapy.

Evaluation of a Combinatorial Immunotherapy Regimen That Can Cure Mice Bearing MYCN-Driven High-Risk Neuroblastoma That Resists Current Clinical Therapy

Background: Incorporating GD2-targeting monoclonal antibody into post-consolidation maintenance therapy has improved survival for children with high-risk neuroblastoma. However, ~50% of patients do not respond to, or relapse following, initial treatment. Here, we evaluated additional anti-GD2-based immunotherapy to better treat high-risk neuroblastoma in mice to develop a regimen for patients with therapy-resistant neuroblastoma. Methods: We determined the components of a combined regimen needed to cure mice of established MYCN-amplified, GD2-expressing, murine 9464D-GD2 neuroblastomas. Results: First, we demonstrate that 9464D-GD2 is nonresponsive to a preferred salvage regimen: anti-GD2 with temozolomide and irinotecan. Second, we have previously shown that adding agonist anti-CD40 mAb and CpG to a regimen of radiotherapy, anti-GD2/IL2 immunocytokine and anti-CTLA-4, cured a substantial fraction of mice bearing small 9464D-GD2 tumors; here, we further characterize this regimen by showing that radiotherapy and hu14.18-IL2 are necessary components, while anti-CTLA-4, anti-CD40, or CpG can individually be removed, and CpG and anti-CTLA-4 can be removed together, while maintaining efficacy. Conclusions: We have developed and characterized a regimen that can cure mice of a high-risk neuroblastoma that is refractory to the current clinical regimen for relapsed/refractory disease. Ongoing preclinical work is directed towards ways to potentially translate these findings to a regimen appropriate for clinical testing.

RBM39 degrader invigorates natural killer cells to eradicate neuroblastoma despite cancer cell plasticity

The cellular plasticity of neuroblastoma is defined by a mixture of two major cell states, adrenergic (ADRN) and mesenchymal (MES), which may contribute to therapy resistance. However, how neuroblastoma cells switch cellular states during therapy remains largely unknown and how to eradicate neuroblastoma regardless of their cell states is a clinical challenge. To better understand the lineage switch of neuroblastoma in chemoresistance, we comprehensively defined the transcriptomic and epigenetic map of ADRN and MES types of neuroblastomas using human and murine models treated with indisulam, a selective RBM39 degrader. We showed that cancer cells not only undergo a bidirectional switch between ADRN and MES states, but also acquire additional cellular states, reminiscent of the developmental pliancy of neural crest cells. The lineage alterations are coupled with epigenetic reprogramming and dependency switch of lineage-specific transcription factors, epigenetic modifiers and targetable kinases. Through targeting RNA splicing, indisulam induces an inflammatory tumor microenvironment and enhances anticancer activity of natural killer cells. The combination of indisulam with anti-GD2 immunotherapy results in a durable, complete response in high-risk transgenic neuroblastoma models, providing an innovative, rational therapeutic approach to eradicate tumor cells regardless of their potential to switch cell states.

Targeting pediatric cancers via T-cell recognition of the monomorphic MHC class I-related protein MR1

Human leukocyte antigen (HLA) restriction of conventional T-cell targeting introduces complexity in generating T-cell therapy strategies for patients with cancer with diverse HLA-backgrounds. A subpopulation of atypical, major histocompatibility complex-I related protein 1 (MR1)-restricted T-cells, distinctive from mucosal-associated invariant T-cells (MAITs), was recently identified recognizing currently unidentified MR1-presented cancer-specific metabolites. It is hypothesized that the MC.7.G5 MR1T-clone has potential as a pan-cancer, pan-population T-cell immunotherapy approach. These cells are irresponsive to healthy tissue while conferring T-cell receptor(TCR) dependent, HLA-independent cytotoxicity to a wide range of adult cancers. Studies so far are limited to adult malignancies. Here, we investigated the potential of MR1-targeting cellular therapy strategies in pediatric cancer. Bulk RNA sequencing data of primary pediatric tumors were analyzed to assess MR1 expression. In vitro pediatric tumor models were subsequently screened to evaluate their susceptibility to engineered MC.7.G5 TCR-expressing T-cells. Targeting capacity was correlated with qPCR-based MR1 mRNA and protein overexpression. RNA expression of MR1 in primary pediatric tumors varied widely within and between tumor entities. Notably, embryonal tumors exhibited significantly lower MR1 expression than other pediatric tumors. In line with this, most screened embryonal tumors displayed resistance to MR1T-targeting in vitro MR1T susceptibility was observed particularly in pediatric leukemia and diffuse midline glioma models. This study demonstrates potential of MC.7.G5 MR1T-cell immunotherapy in pediatric leukemias and diffuse midline glioma, while activity against embryonal tumors was limited. The dismal prognosis associated with relapsed/refractory leukemias and high-grade brain tumors highlights the promise to improve survival rates of children with these cancers.

Silencing of the PHLDA1 leads to global proteome changes and differentiation pathways of human neuroblastoma cells

Neuroblastoma (NB) is the most common extracranial pediatric solid tumor originating from the abnormal development of cells of the sympathoadrenal lineage of the neural crest. Targeting GD2 ganglioside (GD2), a glycolipid expressed on neuroblastoma cells, with GD2 ganglioside-recognizing antibodies affects several pivotal signaling routes that drive or influence the malignant phenotype of the cells. Previously performed gene expression profiling helped us to identify the PHLDA1 (pleckstrin homology-like domain family A member 1) gene as the most upregulated gene in the IMR-32 human neuroblastoma cells treated with the mouse 14G2a monoclonal antibody. Mass spectrometry-based proteomic analyses were applied to better characterize a role of PHLDA1 protein in the response of neuroblastoma cells to chimeric ch14.18/CHO antibody. Additionally, global protein expression profile analysis in the IMR-32 cell line with PHLDA1 silencing revealed the increase in biological functions of mitochondria, accompanied by differentiation-like phenotype of the cells. Moreover, mass spectrometry analysis of the proteins co-immunoprecipitated using anti-PHLDA1-specific antibody, selected a group of possible PHLDA1 binding partners. Also, a more detailed analysis suggested that PHLDA1 interacts with the DCAF7/AUTS2 complex, a key component of neuronal differentiation in vitro. Importantly, our results indicate that PHLDA1 silencing enhances the EGF receptor signaling pathway and combinatory treatment of gefitinib and ch14.18/CHO antibodies might be beneficial for neuroblastoma patients. Data are available via ProteomeXchange with the identifier PXD044319.

Divergent HLA variations and heterogeneous expression but recurrent HLA loss-of- heterozygosity and common HLA-B and TAP transcriptional silencing across advanced pediatric solid cancers

The human leukocyte antigen (HLA) system is a major factor controlling cancer immunosurveillance and response to immunotherapy, yet its status in pediatric cancers remains fragmentary. We determined high-confidence HLA genotypes in 576 children, adolescents and young adults with recurrent/refractory solid tumors from the MOSCATO-01 and MAPPYACTS trials, using normal and tumor whole exome and RNA sequencing data and benchmarked algorithms. There was no evidence for narrowed HLA allelic diversity but discordant homozygosity and allele frequencies across tumor types and subtypes, such as in embryonal and alveolar rhabdomyosarcoma, neuroblastoma MYCN and 11q subtypes, and high-grade glioma, and several alleles may represent protective or susceptibility factors to specific pediatric solid cancers. There was a paucity of somatic mutations in HLA and antigen processing and presentation (APP) genes in most tumors, except in cases with mismatch repair deficiency or genetic instability. The prevalence of loss-of-heterozygosity (LOH) ranged from 5.9 to 7.7% in HLA class I and 8.0 to 16.7% in HLA class II genes, but was widely increased in osteosarcoma and glioblastoma (~15-25%), and for DRB1-DQA1-DQB1 in Ewing sarcoma (~23-28%) and low-grade glioma (~33-50%). HLA class I and HLA-DR antigen expression was assessed in 194 tumors and 44 patient-derived xenografts (PDXs) by immunochemistry, and class I and APP transcript levels quantified in PDXs by RT-qPCR. We confirmed that HLA class I antigen expression is heterogeneous in advanced pediatric solid tumors, with class I loss commonly associated with the transcriptional downregulation of HLA-B and transporter associated with antigen processing (TAP) genes, whereas class II antigen expression is scarce on tumor cells and occurs on immune infiltrating cells. Patients with tumors expressing sufficient HLA class I and TAP levels such as some glioma, osteosarcoma, Ewing sarcoma and non-rhabdomyosarcoma soft-tissue sarcoma cases may more likely benefit from T cell-based approaches, whereas strategies to upregulate HLA expression, to expand the immunopeptidome, and to target TAP-independent epitopes or possibly LOH might provide novel therapeutic opportunities in others. The consequences of HLA class II expression by immune cells remain to be established. Immunogenetic profiling should be implemented in routine to inform immunotherapy trials for precision medicine of pediatric cancers.

Lineage Plasticity: The New Cancer Hallmark on the Block

Plasticity refers to the ability of cells to adopt a spectrum of states or phenotypes. In cancer, it is a critical contributor to tumor initiation, progression, invasiveness, and therapy resistance, and it has recently been recognized as an emerging cancer hallmark. Plasticity can occur as a result of cell-intrinsic factors (e.g., genetic, transcriptional, or epigenetic fluctuations), or through cell-extrinsic cues (e.g., signaling from components of the tumor microenvironment or selective pressure from therapy). Over the past decade, technological advances, analysis of patient samples, and studies in mouse model systems have led to a deeper understanding of how such plastic states come about. In this review, we discuss: (i) the definition of plasticity; (ii) methods to measure and quantify plasticity; (iii) the clinical relevance of plasticity; and (iv) therapeutic hypotheses to modulate plasticity in the clinic.

PRMT5 orchestrates EGFR and AKT networks to activate NFκB and promote EMT

Neuroblastoma remains a formidable challenge in pediatric oncology, representing 15% of cancer-related mortalities in children. Despite advancements in combinatorial and targeted treatments improving survival rates, nearly 50% of patients with high-risk neuroblastoma will ultimately succumb to their disease. Dysregulation of the epithelial-mesenchymal transition (EMT) is a key mechanism of tumor cell dissemination, resulting in metastasis and poor outcomes in many cancers. Our prior work identified PRMT5 as a key regulator of EMT via methylation of AKT at arginine 15, enhancing the expression of EMT-driving transcription factors and facilitating metastasis. Here, we identify that PRMT5 directly regulates the transcription of the epidermal growth factor receptor (EGFR). PRMT5, through independent modulation of the EGFR and AKT pathways, orchestrates the activation of NFκB, resulting in the upregulation of the pro-EMT transcription factors ZEB1, SNAIL, and TWIST1. Notably, EGFR and AKT form a compensatory feedback loop, reinforcing the expression of these EMT transcription factors. Small molecule inhibition of PRMT5 methyltransferase activity disrupts EGFR/AKT signaling, suppresses EMT transcription factor expression and ablates tumor growth in vivo . Our findings underscore the pivotal role of PRMT5 in the control of the EMT program in high-risk neuroblastoma.

Heterogeneity and transcriptional drivers of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous disease with limited treatment options. To characterize TNBC heterogeneity, we defined transcriptional, epigenetic, and metabolic subtypes and subtype-driving super-enhancers and transcription factors by combining functional and molecular profiling with computational analyses. Single-cell RNA sequencing revealed relative homogeneity of the major transcriptional subtypes (luminal, basal, and mesenchymal) within samples. We found that mesenchymal TNBCs share features with mesenchymal neuroblastoma and rhabdoid tumors and that the PRRX1 transcription factor is a key driver of these tumors. PRRX1 is sufficient for inducing mesenchymal features in basal but not in luminal TNBC cells via reprogramming super-enhancer landscapes, but it is not required for mesenchymal state maintenance or for cellular viability. Our comprehensive, large-scale, multiplatform, multiomics study of both experimental and clinical TNBC is an important resource for the scientific and clinical research communities and opens venues for future investigation.

Targeting the myeloid microenvironment in neuroblastoma

Myeloid cells (granulocytes and monocytes/macrophages) play an important role in neuroblastoma. By inducing a complex immunosuppressive network, myeloid cells pose a challenge for the adaptive immune system to eliminate tumor cells, especially in high-risk neuroblastoma. This review first summarizes the pro- and anti-tumorigenic functions of myeloid cells, including granulocytes, monocytes, macrophages, and myeloid-derived suppressor cells (MDSC) during the development and progression of neuroblastoma. Secondly, we discuss how myeloid cells are engaged in the current treatment regimen and explore novel strategies to target these cells in neuroblastoma. These strategies include: (1) engaging myeloid cells as effector cells, (2) ablating myeloid cells or blocking the recruitment of myeloid cells to the tumor microenvironment and (3) reprogramming myeloid cells. Here we describe that despite their immunosuppressive traits, tumor-associated myeloid cells can still be engaged as effector cells, which is clear in anti-GD2 immunotherapy. However, their full potential is not yet reached, and myeloid cell engagement can be enhanced, for example by targeting the CD47/SIRPα axis. Though depletion of myeloid cells or blocking myeloid cell infiltration has been proven effective, this strategy also depletes possible effector cells for immunotherapy from the tumor microenvironment. Therefore, reprogramming of suppressive myeloid cells might be the optimal strategy, which reverses immunosuppressive traits, preserves myeloid cells as effectors of immunotherapy, and subsequently reactivates tumor-infiltrating T cells.

Multiomic analysis of cervical squamous cell carcinoma identifies cellular ecosystems with biological and clinical relevance

Cervical squamous cell carcinoma (CSCC) exhibits a limited response to immune-checkpoint blockade. Here we conducted a multiomic analysis encompassing single-cell RNA sequencing, spatial transcriptomics and spatial proteomics, combined with genetic and pharmacological perturbations to systematically develop a high-resolution and spatially resolved map of intratumoral expression heterogeneity in CSCC. Three tumor states (epithelial-cytokeratin, epithelial-immune (Epi-Imm) and epithelial senescence), recapitulating different stages of squamous differentiation, showed distinct tumor immune microenvironments. Bidirectional interactions between epithelial-cytokeratin malignant cells and immunosuppressive cancer-associated fibroblasts form an immune exclusionary microenvironment through transforming growth factor β pathway signaling mediated by FABP5. In Epi-Imm tumors, malignant cells interact with natural killer and T cells through interferon signaling. Preliminary analysis of samples from a cervical cancer clinical trial ( NCT04516616 ) demonstrated neoadjuvant chemotherapy induces a state transition to Epi-Imm, which correlates with pathological complete remission following treatment with immune-checkpoint blockade. These findings deepen the understanding of cellular state diversity in CSCC.

Dynamical hallmarks of cancer: Phenotypic switching in melanoma and epithelial-mesenchymal plasticity

Phenotypic plasticity was recently incorporated as a hallmark of cancer. This plasticity can manifest along many interconnected axes, such as stemness and differentiation, drug-sensitive and drug-resistant states, and between epithelial and mesenchymal cell-states. Despite growing acceptance for phenotypic plasticity as a hallmark of cancer, the dynamics of this process remains poorly understood. In particular, the knowledge necessary for a predictive understanding of how individual cancer cells and populations of cells dynamically switch their phenotypes in response to the intensity and/or duration of their current and past environmental stimuli remains far from complete. Here, we present recent investigations of phenotypic plasticity from a systems-level perspective using two exemplars: epithelial-mesenchymal plasticity in carcinomas and phenotypic switching in melanoma. We highlight how an integrated computational-experimental approach has helped unravel insights into specific dynamical hallmarks of phenotypic plasticity in different cancers to address the following questions: a) how many distinct cell-states or phenotypes exist?; b) how reversible are transitions among these cell-states, and what factors control the extent of reversibility?; and c) how might cell-cell communication be able to alter rates of cell-state switching and enable diverse patterns of phenotypic heterogeneity? Understanding these dynamic features of phenotypic plasticity may be a key component in shifting the paradigm of cancer treatment from reactionary to a more predictive, proactive approach.

Two bullets in the gun: combining immunotherapy with chemotherapy to defeat neuroblastoma by targeting adrenergic-mesenchymal plasticity

Neuroblastoma (NB) is a childhood tumor that originates in the peripheral sympathetic nervous system and is responsible for 15% of cancer-related deaths in the pediatric population. Despite intensive multimodal treatment, many patients with high-risk NB relapse and develop a therapy-resistant tumor. One of the phenomena related to therapeutic resistance is intratumor heterogeneity resulting from the adaptation of tumor cells in response to different selective environmental pressures. The transcriptional and epigenetic profiling of NB tissue has recently revealed the existence of two distinct cellular identities in the NB, termed adrenergic (ADRN) and mesenchymal (MES), which can spontaneously interconvert through epigenetic regulation. This phenomenon, known as tumor plasticity, has a major impact on cancer pathogenesis. The aim of this review is to describe the peculiarities of these two cell states, and how their plasticity affects the response to current therapeutic treatments, with special focus on the immunogenic potential of MES cells. Furthermore, we will discuss the opportunity to combine immunotherapy with chemotherapy to counteract NB phenotypic interconversion.

Children's Oncology Group's 2023 blueprint for research: Neuroblastoma

Neuroblastoma is the most common extra-cranial solid tumor in children and is known for its clinical heterogeneity. A greater understanding of the biology of this disease has led to both improved risk stratification and new approaches to therapy. Outcomes for children with low and intermediate risk disease are excellent overall, and efforts to decrease therapy for such patients have been largely successful. Although survival has improved over time for patients with high-risk disease and treatments evaluated in the relapse setting are now being moved into earlier phases of treatment, much work remains to improve survival and decrease therapy-related toxicities. Studies of highly annotated biobanked samples continue to lead to important insights regarding neuroblastoma biology. Such studies, along with correlative biology studies incorporated into therapeutic trials, are expected to continue to provide insights that lead to new and more effective therapies. A focus on translational science is accompanied by an emphasis on new agent development, optimized risk stratification, and international collaboration to address questions relevant to molecularly defined subsets of patients. In addition, the COG Neuroblastoma Committee is committed to addressing the patient/family experience, mitigating late effects of therapy, and studying social determinants of health in patients with neuroblastoma.

A Comparative Study of Neuroendocrine Heterogeneity in Small Cell Lung Cancer and Neuroblastoma

Lineage plasticity has long been documented in both small cell lung cancer (SCLC) and neuroblastoma, two clinically distinct neuroendocrine (NE) cancers. In this study, we quantified the NE features of cancer as NE scores and performed a systematic comparison of SCLC and neuroblastoma. We found neuroblastoma and SCLC cell lines have highly similar molecular profiles and shared therapeutic sensitivity. In addition, NE heterogeneity was observed at both the inter- and intra-cell line levels. Surprisingly, we did not find a significant association between NE scores and overall survival in SCLC or neuroblastoma. We described many shared and unique NE score-associated features between SCLC and neuroblastoma, including dysregulation of Myc oncogenes, alterations in protein expression, metabolism, drug resistance, and selective gene dependencies.

IMPLICATIONS

Our work establishes a reference for molecular changes and vulnerabilities associated with NE to non-NE transdifferentiation through mutual validation of SCLC and neuroblastoma samples.

Global Impact of Monoclonal Antibodies (mAbs) in Children: A Focus on Anti-GD2

Monoclonal antibodies (mAbs), as the name implies, are clonal antibodies that bind to the same antigen. mAbs are broadly used as diagnostic or therapeutic tools for neoplasms, autoimmune diseases, allergic conditions, and infections. Although most mAbs are approved for treating adult cancers, few are applicable to childhood malignancies, limited mostly to hematological cancers. As for solid tumors, only anti-disialoganglioside (GD2) mAbs are approved specifically for neuroblastoma. Inequities of drug access have continued, affecting most therapeutic mAbs globally. To understand these challenges, a deeper dive into the complex transition from basic research to the clinic, or between marketing and regulatory agencies, is timely. This review focuses on current mAbs approved or under investigation in pediatric cancer, with special attention on solid tumors and anti-GD2 mAbs, and the hurdles that limit their broad global access. Beyond understanding the mechanisms of drug resistance, the continual discovery of next generation drugs safer for children and easier to administer, the discovery of predictive biomarkers to avoid futility should ease the acceptance by patient, health care professionals and regulatory agencies, in order to expand clinical utility. With a better integration into the multimodal treatment for each disease, protocols that align with the regional clinical practice should also improve acceptance and cost-effectiveness. Communication and collaboration between academic institutions, pharmaceutical companies, and regulatory agencies should help to ensure accessible, affordable, and sustainable health care for all.

T-cell inflammation is prognostic of survival in patients with high-risk neuroblastoma enriched for an adrenergic signature

Purpose

T-cell inflammation (TCI) has been shown to be a prognostic marker in neuroblastoma, a tumor comprised of cells that can exist in two epigenetic states, adrenergic (ADRN) and mesenchymal (MES). We hypothesized that elucidating unique and overlapping aspects of these biologic features could serve as novel biomarkers.

Patients and Methods

We detected lineage-specific, single-stranded super-enhancers defining ADRN and MES specific genes. Publicly available neuroblastoma RNA-seq data from GSE49711 (Cohort 1) and TARGET (Cohort 2) were assigned MES, ADRN, and TCI scores. Tumors were characterized as MES (top 33%) or ADRN (bottom 33%), and TCI (top 67% TCI score) or non-inflamed (bottom 33% TCI score). Overall survival (OS) was assessed using the Kaplan-Meier method, and differences were assessed by the log-rank test.

Results

We identified 159 MES genes and 373 ADRN genes. TCI scores were correlated with MES scores (R=0.56, p<0.001 and R=0.38, p<0.001) and anticorrelated with MYCN -amplification (R=-0.29, p<0.001 and -0.18, p=0.03) in both cohorts. Among Cohort 1 patients with high-risk, ADRN tumors (n=59), those with TCI tumors (n=22) had superior OS to those with non-inflammed tumors (n=37) (p=0.01), though this comparison did not reach significance in Cohort 2. TCI status was not associated with survival in patients with high-risk MES tumors in either cohort.

Conclusions

High inflammation scores were correlated with improved survival in some high-risk patients with, ADRN but not MES neuroblastoma. These findings have implications for approaches to treating high-risk neuroblastoma.

Neural crest-related NXPH1/α-NRXN signaling opposes neuroblastoma malignancy by inhibiting organotropic metastasis

Neuroblastoma is a pediatric cancer that can present as low- or high-risk tumors (LR-NBs and HR-NBs), the latter group showing poor prognosis due to metastasis and strong resistance to current therapy. Whether LR-NBs and HR-NBs differ in the way they exploit the transcriptional program underlying their neural crest, sympatho-adrenal origin remains unclear. Here, we identified the transcriptional signature distinguishing LR-NBs from HR-NBs, which consists mainly of genes that belong to the core sympatho-adrenal developmental program and are associated with favorable patient prognosis and with diminished disease progression. Gain- and loss-of-function experiments revealed that the top candidate gene of this signature, Neurexophilin-1 (NXPH1), has a dual impact on NB cell behavior in vivo: whereas NXPH1 and its receptor α-NRXN1 promote NB tumor growth by stimulating cell proliferation, they conversely inhibit organotropic colonization and metastasis. As suggested by RNA-seq analyses, these effects might result from the ability of NXPH1/α-NRXN signalling to restrain the conversion of NB cells from an adrenergic state to a mesenchymal one. Our findings thus uncover a transcriptional module of the sympatho-adrenal program that opposes neuroblastoma malignancy by impeding metastasis, and pinpoint NXPH1/α-NRXN signaling as a promising target to treat HR-NBs.

Epigenetic therapies for neuroblastoma: immunogenicity awakens

The development of immunotherapies for neuroblastoma remains challenging owing to the low immunogenicity of neuroblastoma cells, as reflected by the low expression of one of the main triggers of immune recognition, the major histocompatibility complex class I (MHC-I). Cornel et al. showed that epigenetic modulation of neuroblastoma cells with a histone deacetylase inhibitor can boost the expression of major histocompatibility complex class I, among other immune receptors, priming their recognition by T- and natural killer cells. By leveraging the developmentally related aberrant epigenetic landscapes of neuroblastoma, these discoveries pave the way to overcome a major limitation in the field of neuroblastoma immunotherapy.

Patient-derived models: Advanced tools for precision medicine in neuroblastoma

Neuroblastoma is a childhood cancer derived from the sympathetic nervous system. High-risk neuroblastoma patients have a poor overall survival and account for ~15% of childhood cancer deaths. There is thus a need for clinically relevant and authentic models of neuroblastoma that closely resemble the human disease to further interrogate underlying mechanisms and to develop novel therapeutic strategies. Here we review recent developments in patient-derived neuroblastoma xenograft models and in vitro cultures. These models can be used to decipher mechanisms of metastasis and treatment resistance, for drug screening, and preclinical drug testing. Patient-derived neuroblastoma models may also provide useful information about clonal evolution, phenotypic plasticity, and cell states in relation to neuroblastoma progression. We summarize current opportunities for, but also barriers to, future model development and application. Integration of patient-derived models with patient data holds promise for the development of precision medicine treatment strategies for children with high-risk neuroblastoma.

Epigenetic modulation of neuroblastoma enhances T cell and NK cell immunogenicity by inducing a tumor-cell lineage switch

BACKGROUND

Immunotherapy in high-risk neuroblastoma (HR-NBL) does not live up to its full potential due to inadequate (adaptive) immune engagement caused by the extensive immunomodulatory capacity of HR-NBL. We aimed to tackle one of the most notable immunomodulatory processes in neuroblastoma (NBL), absence of major histocompatibility complex class I (MHC-I) surface expression, a process greatly limiting cytotoxic T cell engagement. We and others have previously shown that MHC-I expression can be induced by cytokine-driven immune modulation. Here, we aimed to identify tolerable pharmacological repurposing strategies to upregulate MHC-I expression and therewith enhance T cell immunogenicity in NBL.

METHODS

Drug repurposing libraries were screened to identify compounds enhancing MHC-I surface expression in NBL cells using high-throughput flow cytometry analyses optimized for adherent cells. The effect of positive hits was confirmed in a panel of NBL cell lines and patient-derived organoids. Compound-treated NBL cell lines and organoids were cocultured with preferentially expressed antigen of melanoma (PRAME)-reactive tumor-specific T cells and healthy-donor natural killer (NK) cells to determine the in vitro effect on T cell and NK cell cytotoxicity. Additional immunomodulatory effects of histone deacetylase inhibitors (HDACi) were identified by transcriptome and translatome analysis of treated organoids.

RESULTS

Drug library screening revealed MHC-I upregulation by inhibitor of apoptosis inhibitor (IAPi)- and HDACi drug classes. The effect of IAPi was limited due to repression of nuclear factor kappa B (NFκB) pathway activity in NBL, while the MHC-I-modulating effect of HDACi was widely translatable to a panel of NBL cell lines and patient-derived organoids. Pretreatment of NBL cells with the HDACi entinostat enhanced the cytotoxic capacity of tumor-specific T cells against NBL in vitro, which coincided with increased expression of additional players regulating T cell cytotoxicity (eg, TAP1/2 and immunoproteasome subunits). Moreover, MICA and MICB, important in NK cell cytotoxicity, were also increased by entinostat exposure. Intriguingly, this increase in immunogenicity was accompanied by a shift toward a more mesenchymal NBL cell lineage.

CONCLUSIONS

This study indicates the potential of combining (immuno)therapy with HDACi to enhance both T cell-driven and NKcell-driven immune responses in patients with HR-NBL.