Interference of bone marrow CD56+ mesenchymal stromal cells in minimal residual disease investigation of neuroblastoma and other CD45- /CD56+ pediatric malignancies using flow cytometry

Analysis of flow cytometry data from ultrasound-guided lymph node biopsies with two types of needles

BACKGROUND

In this study, we combined two techniques, ultrasound-guided needle biopsy and flow cytometry (FCM), to explore their value in patients with enlarged lymph nodes.

METHODS

We compared the results of 198 needle biopsies on FCM and pathology. Forty-two were done by (fine needle aspiration, FNA), and the remaining 156 with (core needle biopsy, CNB), in 36 of 156 patients, a FNA was performed in the same lymph node after completion of the CNB. Except for five types of pathological entities, the rest were differentiated only detected or undetected tumours as the outcome distinction.

RESULTS

Among the 198 needle biopsies, 13 were inadequate specimens, while the remaining 185 had pathological findings, including 47 benign and 138 neoplastic findings. Thirty-six patients underwent puncture with both FNA and CNB, both needles produced identical results by FCM, but more cells were obtained by FNA. Among the pathologically positive results, there were 23 missed diagnoses in FCM, in contrast, evidence of tumours was observed in the FCM images of 15 needle biopsies that reported benign or findings that were inconsistent with pathology, and the final diagnosis was consistent with the FCM in 10 cases. FCM detected haematolymphoid tumours with a sensitivity of 87.8% and a specificity of 91.9%.

CONCLUSION

The combination of FCM and ultrasound-guided lymph node needle biopsy can quickly provide guidance for clinical decision-making. We recommend that all lymph node needle biopsies be sent for FCM, the specimen can be obtained by the last puncture with FNA.

Utility of Flow Cytometry Analysis in the Detection of Nonhematologic Neoplasms: An Overview

Flow cytometry analysis has stood the test of time as a powerful tool in the assessment of hematologic neoplasms. The role of flow cytometry has expanded to evaluate various nonhematologic neoplasms encountered in body cavity malignant effusions, lymph nodes, and other body sites. This review explores the use of routine antibody panels as well as specially designed multicolor antibody panels that have been investigated by different groups and reported in the literature for evaluating nonhematologic neoplasms. In this context, the limitations, pitfalls, future directions, and promising applications of flow cytometry analysis are also discussed.

Twenty-four-color full spectrum flow cytometry panel for minimal residual disease detection in acute myeloid leukemia

Full spectrum flow cytometry brings a breakthrough for minimal residual disease (MRD) detection in acute myeloid leukemia (AML). We aimed to explore the role of a new panel in MRD detection. We established a 24-color full-spectrum flow cytometry panel. A tube of 24-color antibodies included CD45, CD117, CD34, HLA-DR, CD15, CD64, CD14, CD11c, CD11b, CD13, CD33, CD371, CD7, CD56, CD19, CD4, CD2, CD123, CD200, CD38, CD96, CD71, CD36, and CD9. We discovered that when a tube meets 26 parameters (24 colors), these markers were not only limited to the observation of MRD in AML, but also could be used for fine clustering of bone marrow cells. Mast cells, basophils, myeloid dendritic cells, and plasmacoid dendritic cells were more clearly observed. In addition, immune checkpoint CD96 had the higher expression in CD117+ myeloid naive cells and CD56dimNK cells, while had the lower expression in CD56briNK cells in AML-MRD samples than in normal bone marrow samples. CD200 expression was remarkably enhanced in CD117+ myeloid naive cells, CD4+ T cells, T cells, activated T cells, CD56dimNK cells, and CD56briNK cells in AML-MRD samples. Our results can be used as important basis for auxiliary diagnosis, prognosis judgment, treatment guidance, and immune regulation in AML.

Prognostic significance of NT5E/CD73 in neuroblastoma and its function in CSC stemness maintenance

Cluster of differentiation 73 (CD73), a cell surface enzyme that catalyzes adenosine monophosphate (AMP) breakdown to adenosine, is differentially expressed in cancers and has prognostic significance. We investigated its expression profile in neuroblastoma (NB), its association with NB clinical outcomes, and its influence in the regulation of cancer stem cells' (CSCs) stemness maintenance. RNA-Seq data mining (22 independent study cohorts, total n = 3836) indicated that high CD73 can predict good NB prognosis. CD73 expression (immunohistochemistry) gauged in an NB patient cohort (n = 87) showed a positive correlation with longer overall survival (OS, P = 0.0239) and relapse-free survival (RFS, P = 0.0242). Similarly, high CD73 correlated with longer OS and RFS in advanced disease stages, MYCN non-amplified (MYCN-na), and Stage-4-MYCN-na subsets. Despite no definite association in children < 2 years old (2Y), high CD73 correlated with longer OS (P = 0.0294) and RFS (P = 0.0315) in children > 2Y. Consistently, high CD73 was associated with better OS in MYCN-na, high-risk, and stage-4 subsets of children > 2Y. Multivariate analysis identified CD73 as an independent (P = 0.001) prognostic factor for NB. Silencing CD73 in patient-derived (stage 4, progressive disease) CHLA-171 and CHLA-172 cells revealed cell-line-independent activation of 58 CSC stemness maintenance molecules (QPCR profiling). Overexpressing CD73 in CHLA-20 and CHLA-90 cells with low CD73 and silencing in CHLA-171 and CHLA-172 cells with high CD73 showed that CD73 regulates epithelial to mesenchymal transition (E-Cadherin, N-Cadherin, Vimentin), stemness maintenance (Sox2, Nanog, Oct3/4), self-renewal capacity (Notch), and differentiation inhibition (leukemia inhibitory factor, LIF) proteins (confocal-immunofluorescence). These results demonstrate that high CD73 can predict good prognosis in NB, and further suggest that CD73 regulates stemness maintenance in cells that defy clinical therapy.

BPTF in bone marrow provides a potential progression biomarker regulated by TFAP4 through the PI3K/AKT pathway in neuroblastoma

BACKGROUND

Neuroblastoma (NB) is the most common extracranial malignant solid tumor in children, which is highly prone to bone marrow (BM) metastasis. BM can monitor early signs of mild disease and metastasis. Existing biomarkers are insufficient for the diagnosis and treatment of NB. Bromodomain PHD finger transcription factor (BPTF) is an important subunit of the chromatin-remodeling complex that is closely associated with tumors. Here, we evaluated whether BPTF in BM plays an important role in predicting NB progression, and explore the molecular mechanism of BPTF in NB.

METHODS

The clinical relevance of the BPTF was predicted in the GEO (GSE62564) and TARGET database. The biological function of BPTF in NB was investigated by constructing cell lines and employing BPTF inhibitor AU1. Western blot was used to determine the changes of BPTF, TFAP4, PI3K/AKT signaling and Epithelial-mesenchymal transition (EMT) related markers. A total of 109 children with newly diagnosed NB in Beijing Children's Hospital from January 2018 to March 2021 were included in this study. RT-PCR was used to measure the BPTF and TFAP4 expression in BM. The cut-off level was set at the median value of BPTF expression levels.

RESULTS

Databases suggested that BPTF expression was higher in NB and was significantly associated with stage and grade. Proliferation and migration of NB cells were slowed down when BPTF was silenced. Mechanistically, TFAP4 could positively regulate BPTF and promotes EMT process through activating the PI3K/AKT signaling pathway. Moreover, detection of the newly diagnosed BM specimens showed that BPTF expression was significantly higher in high-risk group, stage IV group and BM metastasis group. Children with high BPTF at initial diagnosis were considered to have high risk for disease progression and recurrence. BPTF is an independent risk factor for predicting NB progression.

CONCLUSIONS

A novel and convenient BPTF-targeted humoral detection that can prompt minimal residual and predict NB progression in the early stages of the disease were identified. BPTF inhibitor AU1 is expected to become a new targeted drug for NB therapy. It's also reveal previously unknown mechanisms of BPTF in NB cell proliferation and metastasis through TFAP4 and PI3K/AKT pathways.

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.

TH-MYCN tumors, but not tumor-derived cell lines, are adrenergic lineage, GD2+, and responsive to anti-GD2 antibody therapy

Neuroblastoma is a commonly lethal solid tumor of childhood and intensive chemoradiotherapy treatment cures ~50% of children with high-risk disease. The addition of immunotherapy using dinutuximab, a monoclonal antibody directed against the GD2 disialoganglioside expressed on neuroblasts, improves survival when incorporated into front-line therapy and shows robust activity in regressing relapsed disease when combined with chemotherapy. Still, many children succumb to neuroblastoma progression despite receiving dinutuximab-based immunotherapy, and efforts to counteract the immune suppressive signals responsible are warranted. Animal models of human cancers provide useful platforms to study immunotherapies. TH-MYCN transgenic mice are immunocompetent and develop neuroblastomas at autochthonous sites due to enforced MYCN expression in developing neural crest tissues. However, GD2-directed immunotherapy in this model has been underutilized due to the prevailing notion that TH-MYCN neuroblasts express insufficient GD2 to be targeted. We demonstrate that neuroblasts in TH-MYCN-driven tumors express GD2 at levels comparable to human neuroblastomas but rapidly lose GD2 expression when explanted ex vivo to establish tumor cell lines. This occurs in association with a transition from an adrenergic to mesenchymal differentiation state. Importantly, not only is GD2 expression retained on tumors in situ, treatment with a murine anti-GD2 antibody, 14G2a, markedly extends survival in such mice, including durable complete responses. Tumors in 14G2a-treated mice have fewer macrophage and myeloid-derived suppressor cells in their tumor microenvironment. Our findings support the utility of this model to inform immunotherapy approaches for neuroblastoma and potential opportunities to investigate drivers of adrenergic to mesenchymal fate decisions.

GPC2-CAR T cells tuned for low antigen density mediate potent activity against neuroblastoma without toxicity

Pediatric cancers often mimic fetal tissues and express proteins normally silenced postnatally that could serve as immune targets. We developed T cells expressing chimeric antigen receptors (CARs) targeting glypican-2 (GPC2), a fetal antigen expressed on neuroblastoma (NB) and several other solid tumors. CARs engineered using standard designs control NBs with transgenic GPC2 overexpression, but not those expressing clinically relevant GPC2 site density (∼5,000 molecules/cell, range 1-6 × 10³). Iterative engineering of transmembrane (TM) and co-stimulatory domains plus overexpression of c-Jun lowered the GPC2-CAR antigen density threshold, enabling potent and durable eradication of NBs expressing clinically relevant GPC2 antigen density, without toxicity. These studies highlight the critical interplay between CAR design and antigen density threshold, demonstrate potent efficacy and safety of a lead GPC2-CAR candidate suitable for clinical testing, and credential oncofetal antigens as a promising class of targets for CAR T cell therapy of solid tumors.

Flow Cytometry Immunophenotyping for Diagnostic Orientation and Classification of Pediatric Cancer Based on the EuroFlow Solid Tumor Orientation Tube (STOT)

Simple Summary

Pediatric solid tumors are a heterogenous group of diseases that comprise ≈ 40% of all pediatric cancers, early diagnosis being key for improved survival. Here we designed, tested, and validated a single eight-color tube for the diagnostic screening of pediatric cancer—solid tumor orientation tube (STOT)—based on multiparameter flow cytometry vs. conventional diagnostic procedures. Prospective clinical validation of STOT in 149 samples (63 tumor mass, 38 bone marrow, 30 lymph node, and 18 body fluid samples) screened for pediatric cancer, apart from 26 blood specimens that were excluded from analysis, showed concordant results with the final WHO/ICCC-3 diagnosis in 138/149 cases (92.6%). This included correct diagnostic orientation by STOT in 43/44 (98%) malignant and 4/4 (100%) benign non-hematopoietic tumors, together with 28/38 (74%) leukemia/lymphoma cases. The only recurrently missed diagnosis was Hodgkin lymphoma (0/8), which would require additional markers. These results support the use of STOT as a complementary tool for fast and accurate diagnostic screening, orientation, and classification of pediatric cancer in suspicious patients.

Abstract

Early diagnosis of pediatric cancer is key for adequate patient management and improved outcome. Although multiparameter flow cytometry (MFC) has proven of great utility in the diagnosis and classification of hematologic malignancies, its application to non-hematopoietic pediatric tumors remains limited. Here we designed and prospectively validated a new single eight-color antibody combination—solid tumor orientation tube, STOT—for diagnostic screening of pediatric cancer by MFC. A total of 476 samples (139 tumor mass, 138 bone marrow, 86 lymph node, 58 peripheral blood, and 55 other body fluid samples) from 296 patients with diagnostic suspicion of pediatric cancer were analyzed by MFC vs. conventional diagnostic procedures. STOT was designed after several design–test–evaluate–redesign cycles based on a large panel of monoclonal antibody combinations tested on 301 samples. In its final version, STOT consists of a single 8-color/12-marker antibody combination (CD99-CD8/_numyogenin/CD4-EpCAM/CD56/GD2/_smCD3-CD19/_cyCD3-CD271/CD45). Prospective validation of STOT in 149 samples showed concordant results with the patient WHO/ICCC-3 diagnosis in 138/149 cases (92.6%). These included: 63/63 (100%) reactive/disease-free samples, 43/44 (98%) malignant and 4/4 (100%) benign non-hematopoietic tumors together with 28/38 (74%) leukemia/lymphoma cases; the only exception was Hodgkin lymphoma that required additional markers to be stained. In addition, STOT allowed accurate discrimination among the four most common subtypes of malignant CD45⁻ CD56⁺⁺ non-hematopoietic solid tumors: 13/13 (GD2⁺⁺ _numyogenin⁻ CD271^−/+ _nuMyoD1⁻ CD99⁻ EpCAM⁻) neuroblastoma samples, 5/5 (GD2⁻ _numyogenin⁺⁺ CD271⁺⁺ _nuMyoD1⁺⁺ CD99^−/+ EpCAM⁻) rhabdomyosarcomas, 2/2 (GD2^−/+ _numyogenin⁻ CD271⁺ _nuMyoD1⁻ CD99⁺ EpCAM⁻) Ewing sarcoma family of tumors, and 7/7 (GD2⁻ _numyogenin⁻ CD271⁺ _nuMyoD1⁻ CD99⁻ EpCAM⁺) Wilms tumors. In summary, here we designed and validated a new standardized antibody combination and MFC assay for diagnostic screening of pediatric solid tumors that might contribute to fast and accurate diagnostic orientation and classification of pediatric cancer in routine clinical practice.

Flow cytometry as a diagnostic tool in neuroblastoma

In recent years, there has been an expansion in the use of flow cytometry (FC) immunophenotyping in the diagnosis and monitoring of childhood solid neoplasms. Neuroblastoma (NB), in turn, is the most common extracranial solid tumor in childhood. In the present study, we sought to compare FC and anatomopathological examination (PA) / immunohistochemistry (IHC) of children diagnosed or suspected with NB. The median age was 59 months (minimum 0; maximum 325 months), of these 12 were male (57.1%, 12/21). Forty-eight samples (27 bone marrow (BM), 10 peripheral blood (PB), 8 primary tumors (PT) and 2 liver nodules (HN) and 1 rib fragment (RF)) from 21 patients were evaluated. Twenty-nine samples were from patients with clinical suspicion while 19 samples were from patients with previously confirmed diagnosis. Thirteen samples (7 BM, 5 PT and 1 HN) presented NB when analyzed in FC while 8 (3 BM and 5 PT) samples were positive for NB in the PA/IHC. They were concordant in 88.9% of the cases. No NB cells were identified in any PB. Considering the PA as the gold standard, the FC obtained a sensitivity of 100%, a specificity of 86%, a positive predictive value of 67% and a negative predictive value of 100%. This study demonstrates that FC can be used as a methodology for diagnosis and assessment of NB involvement. In addition, FC has the advantage of allowing a quick diagnosis and accurate classification of the disease, and can also assist in monitoring the treatment.

Multiparametric flow cytometry highlights B7-H3 as a novel diagnostic/therapeutic target in GD2neg/low neuroblastoma variants

Background

High-risk neuroblastomas (HR-NBs) are rare, aggressive pediatric cancers characterized by resistance to therapy and relapse in more than 30% of cases, despite using an aggressive therapeutic protocol including targeting of GD2. The mechanisms responsible for therapy resistance are unclear and might include the presence of GD2neg/low NB variants and/or the expression of immune checkpoint ligands such as B7-H3.

Method

Here, we describe a multiparametric flow cytometry (MFC) combining the acquisition of 10⁶ nucleated singlets, Syto16pos CD45neg CD56pos cells, and the analysis of GD2 and B7-H3 surface expression. 41 bone marrow (BM) aspirates from 25 patients with NB, at the onset or relapse, are analyzed, comparing results with cytomorphological analysis (CA) and/or immunohistochemistry (IHC). Spike in experiments assesses the sensitivity of MFC. Kaplan-Meier analysis on 498 primary NBs selects novel prognostic markers possibly integrating the MFC panel.

Results

No false positive are detected, and MFC shows high sensitivity (0.0005%). Optimized MFC identifies CD45negCD56pos NB cells in 11 out of 12 (91.6%) of BM indicated as infiltrated by CA, 7 of which coexpress high levels of GD2 and B7-H3. MFC detects CD45negCD56posGD2neg/low NB variants expressing high surface levels of B7-H3 in two patients with HR-NB (stage M) diagnosed at 53 and 139 months of age. One of them has a non-MYCN amplified tumor with unusual THpos PHOX2Bneg phenotype, which relapsed 141 months post-diagnosis with BM infiltration and a humerus lesion. All GD2neg/low NB variants are detected in patients at relapse. Kaplan-Meier analysis highlights an interesting dichotomous prognostic value of MML5, ULBPs, PVR, B7-H6, and CD47, ligands involved in NB recognition by the immune system.

Conclusions

Our study validates a sensitive MFC analysis providing information on GD2 and B7-H3 surface expression and allowing fast, specific and sensitive evaluation of BM tumor burden. With other routinely used diagnostic and prognostic tools, MFC can improve diagnosis, prognosis, orienting novel personalized treatments in patients with GD2low/neg NB, who might benefit from innovative therapies combining B7-H3 targeting.

A narrative review of central nervous system involvement in acute leukemias

Acute leukemias (both myeloid and lymphoblastic) are a group of diseases for which each year more successful therapies are implemented. However, in a subset of cases the overall survival (OS) is still exceptionally low due to the infiltration of leukemic cells in the central nervous system (CNS) and the subsequent formation of brain tumors. The CNS involvement is more common in acute lymphocytic leukemia (ALL), than in adult acute myeloid leukemia (AML), although the rates for the second case might be underestimated. The main reasons for CNS invasion are related to the expression of specific adhesion molecules (VLA-4, ICAM-1, VCAM, L-selectin, PECAM-1, CD18, LFA-1, CD58, CD44, CXCL12) by a subpopulation of leukemic cells, called “sticky cells” which have the ability to interact and adhere to endothelial cells. Moreover, the microenvironment becomes hypoxic and together with secretion of VEGF-A by ALL or AML cells the permeability of vasculature in the bone marrow increases, coupled with the disruption of blood brain barrier. There is a single subpopulation of leukemia cells, called leukemia stem cells (LSCs) that is able to resist in the new microenvironment due to its high adaptability. The LCSs enter into the arachnoid, migrate, and intensively proliferate in cerebrospinal fluid (CSF) and consequently infiltrate perivascular spaces and brain parenchyma. Moreover, the CNS is an immune privileged site that also protects leukemic cells from chemotherapy. CD56/NCAM is the most important surface molecule often overexpressed by leukemic stem cells that offers them the ability to infiltrate in the CNS. Although asymptomatic or with unspecific symptoms, CNS leukemia should be assessed in both AML/ALL patients, through a combination of flow cytometry and cytological analysis of CSF. Intrathecal therapy (ITT) is a preventive measure for CNS involvement in AML and ALL, still much research is needed in finding the appropriate target that would dramatically lower CNS involvement in acute leukemia.