Minimal residual disease in high-risk neuroblastoma shows a dynamic and disease burden-dependent correlation between bone marrow and peripheral blood

Recommendations for the use of nuclear medicine imaging in patients with neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid cancer in children. Despite intensive multimodality treatment, long-term survival of patients with high-risk NB, which comprises more than half of all cases, remains poor. Nuclear medicine is key in diagnosis, staging, response assessment and long-term follow-up of NB. The emergence of novel tracers and the increasing complexity of studies require updated guidelines for nuclear medicine imaging in NB. Standardising diagnostic techniques are essential for improving study comparability and ensuring test quality. This article aims to provide a comprehensive review of NB radionuclide diagnostic imaging, including its characteristics, accuracy, advantages, and limitations. It offers practical recommendations to multidisciplinary teams responsible for treating patients with NB. This review summarises the opinions of leading experts from the Neuroblastoma Spanish Group within the Spanish Society of Paediatric Haematology and Oncology (SEHOP) and the Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM).

Evaluation of Minimal Residual Disease in Patients with Neuroblastoma

Neuroblastoma (NB) is a pediatric extracranial solid tumor that accounts for approximately 15% of all pediatric cancer deaths. More than 50% of patients with newly diagnosed NB are classified into a high-risk group with an approximately 50% long-term survival rate. Although most high-risk patients with NB achieve remission, more than half may have minimal residual disease (MRD) that eventually causes relapse. Looking towards an optimal outcome, the accurate evaluation of MRD in patients with NB (NB-MRD) is essential to monitor the treatment response and disease burden. Over the past decades, the quantification of NB-associated messenger RNA (NB-mRNA) by reverse transcriptase-polymerase chain reaction has become widely used to detect NB-MRD, owing to the lack of recurrent genomic aberrations in NB cells. To achieve a more accurate and sensitive detection, the current NB-MRD assays quantify a set of NB-mRNAs to detect NB cells in bone marrow, peripheral blood, and peripheral blood stem cell samples. Among a growing number of NB-MRD assays, several assays quantitating different but overlapping sets of NB-mRNAs are reported to have a significant prognostic value. However, the clinical significance of NB-MRD remains to be established. In this review, we summarize the recent progress in NB-MRD and evaluate its clinical value.

The anti-GD2 monoclonal antibody naxitamab plus GM-CSF for relapsed or refractory high-risk neuroblastoma: a phase 2 clinical trial

In this single-arm, non-randomized, phase 2 trial (NCT03363373), 74 patients with relapsed/refractory high-risk neuroblastoma and residual disease in bone/bone marrow (BM) received naxitamab on Days 1, 3, and 5 (3 mg/kg/day) with granulocyte-macrophage colony-stimulating factor (Days -4 to 5) every 4 weeks, until complete response (CR) or partial response (PR) followed by 5 additional cycles every 4 weeks. Primary endpoint in the prespecified interim analysis was overall response (2017 International Neuroblastoma Response Criteria). Among 26 responders (CR + PR) in the efficacy population (N = 52), 58% had refractory disease, and 42% had relapsed disease. Overall response rate (ORR) was 50% (95% CI: 36-64%), and CR and PR were observed in 38% and 12%, respectively. With the 95% CI lower limit for ORR exceeding 20%, the primary endpoint of overall response was met. Patients with evaluable bone disease had a 58% (29/50) bone compartment response (CR, 40%; PR, 18%). BM compartment response was 74% (17/23; CR, 74%). One-year overall survival and progression-free survival (secondary endpoints) were 93% (95% CI: 80-98%) and 35% (95% CI: 16-54%), respectively. Naxitamab-related Grade 3 adverse events included hypotension (58%) and pain (54%). Overall, naxitamab demonstrated clinically meaningful efficacy with manageable safety in patients with residual neuroblastoma in bone/BM.

Updates on liquid biopsies in neuroblastoma for treatment response, relapse and recurrence assessment

Neuroblastoma is a paediatric malignancy of the sympathoadrenal or Schwann cells derived from the neural crest. Risk stratification in neuroblastoma is informed by MYCN amplification, age, stage, ploidy, and segmental chromosomal alterations. High-risk cases bear dismal overall survival. A panel of pathology and imaging modalities are utilised for diagnosis, while treatment strategies depend on the risk group. Despite this, relapse can occur in 50% of high-risk neuroblastoma patients in remission post-treatment. Liquid biopsies typically comprise the sampling of the peripheral blood and are attractive since they are less invasive than surgical tumour tissue biopsies. Liquid biopsies retrieve circulating tumour DNA and circulating tumour RNA released by tumours in addition to circulating tumour cells. These biological materials can be utilised to analyse tumour genetic alterations. Monitoring tumour-derived molecular information can assist diagnostics, targeted therapy selection, and treatment while reflecting minimal residual disease, relapse, and recurrence. This study aims to review the latest research on liquid biopsies for disease diagnosis, assessing treatment efficacy, minimal residual disease, relapse, and recurrence in neuroblastoma. A deeper understanding of the application of liquid biopsies could inform future prospective clinical trials, and in time, facilitate their routine implementation in clinical practice.

Salvage chemotherapy regimens with arsenic trioxide for relapsed or refractory neuroblastoma: a promising approach

In patients with relapsed or refractory neuroblastoma (NB), the limited efficacy of conventional chemotherapies necessitates the exploration of new treatment options. Previous studies have highlighted the anti-tumor properties of arsenic trioxide (ATO) in high-risk NB (HR-NB). This study aims to assess the effectiveness and safety of ATO combined with salvage chemotherapy regimens, featuring cyclophosphamide and topotecan, as a foundational treatment for children with relapsed or refractory NB. Eleven patients (four relapsed, seven refractory NB) were retrospectively analyzed for efficacy and treatment relevance. Salvage treatments, incorporating ATO (0.18 mg/kg daily for 8 h intravenously on days 1 to 10), were administered upon disease progression or relapse, with assessments conducted every two cycles. Treatments had 63.6% efficacy, with six cases of partial response, one case of stable disease, and four cases of disease progression. The overall response rate was 54.5%, and the disease control rate was 63.6%. Importantly, the systemic toxicity experienced by patients following salvage chemotherapy with ATO was mild. Salvage chemotherapy regimens featuring ATO demonstrated potential for prolonging disease stabilization for relapsed or refractory HR-NB patients, exhibiting both favorable efficacy and safety profiles. This suggests further clinical exploration and promotion of this therapeutic approach in the treatment of NB.

Distinct Expression Profiles of Neuroblastoma-Associated mRNAs in Peripheral Blood and Bone Marrow of Non-High-Risk and High-Risk Neuroblastoma Patients

Non-high-risk (non-HR) neuroblastoma (NB) patients have excellent outcomes, with more than a 90% survival rate, whereas HR NB patients expect less than a 50% survival rate. Metastatic disease is the principal cause of death among both non-HR and HR NB patients. Previous studies have reported the significant but limited prognostic value of quantitative PCR (qPCR)-based assays, measuring overlapping but different sets of neuroblastoma-associated mRNAs (NB-mRNAs), to detect metastatic disease in both non-HR and HR patient samples. A droplet digital PCR (ddPCR)-based assay measuring seven NB-mRNAs (CRMP1, DBH, DDC, GAP43, ISL1, PHOX2B, and TH mRNAs) was recently developed and exhibited a better prognostic value for HR patient samples than qPCR-based assays. However, it remained to be tested on non-HR patient samples. In the present study, we employed the ddPCR-based assay to study peripheral blood (PB) and bone marrow (BM) samples collected at diagnosis from eight non-HR and eleven HR cases and characterized the expression profiles of NB-mRNAs. The most highly expressed NB-mRNAs in PB and BM differed between non-HR and HR cases, with the CRMP1 mRNA being predominant in non-HR cases and the GAP43 mRNA in HR cases. The levels of NB-mRNAs in PB and BM were 5 to 1000 times lower in non-HR cases than in HR cases. The PB to BM ratio of NB-mRNAs was 10 to 100 times higher in non-HR cases compared to HR cases. The present case series suggests that non-HR and HR NB patients have the distinct expression profiles of NB-mRNAs in their PB and BM.

Higher levels of minimal residual disease in peripheral blood than bone marrow before 1st and 2nd relapse/regrowth in a patient with high‑risk neuroblastoma: A case report

More than half of patients with high-risk neuroblastoma (HR-NB) experience relapse/regrowth due to the activation of chemoresistant minimal residual disease (MRD). MRD in patients with HR-NB can be evaluated by quantitating neuroblastoma-associated mRNAs (NB-mRNAs) in bone marrow (BM) and peripheral blood (PB) samples. Although several sets of NB-mRNAs have been shown to possess a prognostic value for MRD in BM samples (BM-MRD), MRD in PB samples (PB-MRD) is considered to be low and difficult to evaluate. The present report describes an HR-NB case presenting higher PB-MRD than BM-MRD before 1st and 2nd relapse/regrowth. A 3-year-old female presented with an abdominal mass, was diagnosed with HR-NB, and treated according to the nationwide standard protocol for HR-NB. Following systemic induction and consolidation therapy with local therapy, the patient achieved complete remission but experienced a 1st relapse/regrowth 6 months after maintenance therapy. The patient partially responded to salvage chemotherapy and anti-GD2 immunotherapy but had a 2nd relapse/regrowth 14 months after the 1st relapse/regrowth. Consecutive PB-MRD and BM-MRD monitoring revealed that PB-MRD was lower than BM-MRD at diagnosis (100 times) and 1st and 2nd relapse/regrowth (1,000 and 3 times) but became higher than BM-MRD before 1st and 2nd relapse/regrowth. The present case highlights that PB-MRD can become higher than BM-MRD before relapse/regrowth of patients with HR-NB.

Biological Insight and Recent Advancement in the Treatment of Neuroblastoma

One of the most frequent solid tumors in children is neuroblastoma, which has a variety of clinical behaviors that are mostly influenced by the biology of the tumor. Unique characteristics of neuroblastoma includes its early age of onset, its propensity for spontaneous tumor regression in newborns, and its high prevalence of metastatic disease at diagnosis in individuals older than 1 year of age. Immunotherapeutic techniques have been added to the previously enlisted chemotherapeutic treatments as therapeutic choices. A groundbreaking new treatment for hematological malignancies is adoptive cell therapy, specifically chimeric antigen receptor (CAR) T cell therapy. However, due to the immunosuppressive nature of the tumor microenvironment (TME) of neuroblastoma tumor, this treatment approach faces difficulties. Numerous tumor-associated genes and antigens, including the MYCN proto-oncogene (MYCN) and disialoganglioside (GD2) surface antigen, have been found by the molecular analysis of neuroblastoma cells. The MYCN gene and GD2 are two of the most useful immunotherapy findings for neuroblastoma. The tumor cells devise numerous methods to evade immune identification or modify the activity of immune cells. In addition to addressing the difficulties and potential advancements of immunotherapies for neuroblastoma, this review attempts to identify important immunological actors and biological pathways involved in the dynamic interaction between the TME and immune system.

Combined analysis of PHOX2B at two time points and its value for further risk stratification in high-risk neuroblastoma

BACKGROUND

Risk stratification of high-risk neuroblastoma (NB) is crucial for exploring treatments. This study aimed to explore the value of minimal residual disease (MRD) based on PHOX2B levels for further risk stratification in high-risk NB.

METHODS

The expression of PHOX2B was monitored at two time points (after two and six cycles of induction chemotherapy, TP1 and TP2, respectively) by real-time polymerase chain reaction (RT-PCR). The clinical characteristics between groups and survival rates were analyzed.

RESULTS

The study included 151 high-risk patients. Positive expression of PHOX2B at diagnosis was seen in 129 cases. PHOX2B was mainly expressed in patients with high lactate dehydrogenase (LDH) and neuron-specific enolase (NSE) levels (p < .001), bone marrow metastasis (p < .001), more than three metastatic organs (p < .001), 11q23 loss of heterozygosity (LOH) (p = .007), and when more events occurred (p = .012). The 4-year EFS rate was significantly lower in patients with positive PHOX2B expression compared to the negative group at diagnosis (32.9% ± 6.2% vs. 74.5% ± 10.1%, p = .005). We stratified the 151 patients into three MRD risk groups: low high-risk (low-HR), with TP1 less than 10^-4 and TP2 less than 10^-4 ; ultra-HR, with TP1 greater than or equal to 10^-2 or TP2 greater than or equal to 10^-4 , and others classified as intermediate-HR. Patients in ultra-HR had the worst survival rate compared with other two groups (p = .02). In a multivariate model, MRD risk stratification based on PHOX2B levels at TP1 and TP2 was an independent prognostic factor for high-risk patients (p = .001). Patients in ultra-HR were associated with 11q23 LOH (p < .001), more than three organs of metastasis (p = .005), bone marrow metastasis (p < .001), and occurrence of more events (p = .009).

CONCLUSIONS

MRD risk stratification based on PHOX2B levels at two time points (after two and six cycles of induction chemotherapy) provided a stratification system for high-risk NB, which successfully predicted treatment outcomes. Our results present an effective method for further stratification of high-risk NB.

Minimal residual disease detected by droplet digital PCR in peripheral blood stem cell grafts has a prognostic impact on high-risk neuroblastoma patients

More than half of high-risk neuroblastoma (NB) patients have experienced relapse due to the activation of chemoresistant minimal residual disease (MRD) even though they are treated by high-dose chemotherapy with autologous peripheral blood stem cell (PBSC) transplantation. Although MRD in high-risk NB patients can be evaluated by quantitative PCR with several sets of neuroblastoma-associated mRNAs (NB-mRNAs), the prognostic significance of MRD in PBSC grafts (PBSC-MRD) is unclear. In the present study, we collected 20 PBSC grafts from 20 high-risk NB patients and evaluated PBSC-MRD detected by droplet digital PCR (ddPCR) with 7NB-mRNAs (CRMP1, DBH, DDC, GAP43, ISL1, PHOX2B, and TH mRNA). PBSC-MRD in 11 relapsed patients was significantly higher than that in 9 non-relapsed patients. Patients with a higher PBSC-MRD had a lower 3-year event-free survival (P = 0.0148). The present study suggests that PBSC-MRD detected by ddPCR with 7NB-mRNAs has a prognostic impact on high-risk NB patients.

Pro-metastatic and mesenchymal gene expression signatures characterize circulating tumor cells of neuroblastoma patients with bone marrow metastases and relapse

Existing marker-based methods of minimal residual disease (MRD) determination in neuroblastoma do not effectively enrich for the circulating disease cell population. Given the relative size differential of neuroblastoma tumor cells over normal hematogenous cells, we hypothesized that cell size-based separation could enrich circulating tumor cells (CTCs) from blood samples and disseminated tumor cells (DTCs) from bone marrow aspirates (BMA) of neuroblastoma patients, and that their gene expression profiles could vary dynamically with various disease states over the course of treatment. Using a spiral microfluidic chip, peripheral blood of 17 neuroblastoma patients at 3 serial treatment timepoints (diagnosis, n=17; post-chemotherapy, n=11; and relapse, n=3), and bone marrow samples at diagnosis were enriched for large intact circulating cells. Profiling the resulting enriched samples with immunohistochemistry and mRNA expression of 1490 cancer-related genes via NanoString, 13 of 17 samples contained CTCs displaying cytologic atypia, TH and PHOX2B expression and/or upregulation of cancer-associated genes. Gene signatures reflecting pro-metastatic processes and the neuroblastoma mesenchymal super-enhancer state were consistently upregulated in 7 of 13 samples, 6 of which also had metastatic high-risk disease. Expression of 8 genes associated with PI3K and GCPR signaling were significantly upregulated in CTCs of patients with bone marrow metastases versus patients without. Correspondingly, in patients with marrow metastases, differentially-expressed gene signatures reflected upregulation of immune regulation in bone marrow DTCs versus paired CTCs samples. In patients who later developed disease relapse, 5 genes involved in immune cell regulation, JAK/STAT signaling and the neuroblastoma mesenchymal super-enhancer state (OLFML2B, STAT1, ARHGDIB, STAB1, TLR2) were upregulated in serial CTC samples over their disease course, despite urinary catecholamines and bone marrow aspirates not indicating the disease recurrences. In summary, using a label-free cell size-based separation method, we enriched and characterized intact circulating cells in peripheral blood indicative of neuroblastoma CTCs, as well as their DTC counterparts in the bone marrow. Expression profiles of pro-metastatic genes in CTCs correlated with the presence of bone marrow metastases at diagnosis, while longitudinal profiling identified persistently elevated expression of genes in CTCs that may serve as novel predictive markers of hematogenous MRD in neuroblastoma patients that subsequently relapse.

The Effect of Low Doses of Zearalenone (ZEN) on the Bone Marrow Microenvironment and Haematological Parameters of Blood Plasma in Pre-Pubertal Gilts

The aim of this study was to determine whether low doses of zearalenone (ZEN) influence the carry-over of ZEN and its metabolites to the bone marrow microenvironment and, consequently, haematological parameters. Pre-pubertal gilts (with a body weight of up to 14.5 kg) were exposed to daily ZEN doses of 5 μg/kg BW (group ZEN5, n = 15), 10 μg/kg BW (group ZEN10, n = 15), 15 μg/kg BW (group ZEN15, n = 15), or were administered a placebo (group C, n = 15) throughout the entire experiment. Bone marrow was sampled on three dates (exposure dates 7, 21, and 42—after slaughter) and blood for haematological analyses was sampled on 10 dates. Significant differences in the analysed haematological parameters (WBC White Blood Cells, MONO—Monocytes, NEUT—Neutrophils, LYMPH—Lymphocytes, LUC—Large Unstained Cells, RBC—Red Blood Cells, HGB—Haemoglobin, HCT—Haematocrit, MCH—Mean Corpuscular Volume, MCHC—Mean Corpuscular Haemoglobin Concentrations, PLT—Platelet Count and MPV—Mean Platelet Volume) were observed between groups. The results of the experiment suggest that exposure to low ZEN doses triggered compensatory and adaptive mechanisms, stimulated the local immune system, promoted eryptosis, intensified mycotoxin biotransformation processes in the liver, and produced negative correlations between mycotoxin concentrations and selected haematological parameters.