Neuroblastoma and DIPG Organoid Coculture System for Personalized Assessment of Novel Anticancer Immunotherapies.

Cancer immunotherapy has transformed the landscape of adult cancer treatment and holds a great promise to treat paediatric malignancies. However, in vitro test coculture systems to evaluate the efficacy of immunotherapies on representative paediatric tumour models are lacking. Here, we describe a detailed procedure for the establishment of an ex vivo test coculture system of paediatric tumour organoids and immune cells that enables assessment of different immunotherapy approaches in paediatric tumour organoids. We provide a step-by-step protocol for an efficient generation of patient-derived diffuse intrinsic pontine glioma (DIPG) and neuroblastoma organoids stably expressing eGFP-ffLuc transgenes using defined serum-free medium. In contrast to the chromium-release assay, the new platform allows for visualization, monitoring and robust quantification of tumour organoid cell cytotoxicity using a non-radioactive assay in real-time. To evaluate the utility of this system for drug testing in the paediatric immuno-oncology field, we tested our in vitro assay using a clinically used immunotherapy strategy for children with high-risk neuroblastoma, dinutuximab (anti-GD2 monoclonal antibody), on GD2 proficient and deficient patient-derived neuroblastoma organoids. We demonstrated the feasibility and sensitivity of our ex vivo coculture system using human immune cells and paediatric tumour organoids as ex vivo tumour models. Our study provides a novel platform for personalized testing of potential anticancer immunotherapies for aggressive paediatric cancers such as neuroblastoma and DIPG.

Immune Monitoring during Therapy Reveals Activitory and Regulatory Immune Responses in High-Risk Neuroblastoma.

Despite intensive treatment, including consolidation immunotherapy (IT), prognosis of high-risk neuroblastoma (HR-NBL) is poor. Immune status of patients over the course of treatment, and thus immunological features potentially explaining therapy efficacy, are largely unknown. In this study, the dynamics of immune cell subsets and their function were explored in 25 HR-NBL patients at diagnosis, during induction chemotherapy, before high-dose chemotherapy, and during IT. The dynamics of immune cells varied largely between patients. IL-2- and GM-CSF-containing IT cycles resulted in significant expansion of effector cells (NK-cells in IL-2 cycles, neutrophils and monocytes in GM-CSF cycles). Nonetheless, the cytotoxic phenotype of NK-cells was majorly disturbed at the start of IT, and both IL-2 and GM-CSF IT cycles induced preferential expansion of suppressive regulatory T-cells. Interestingly, proliferative capacity of purified patient T-cells was impaired at diagnosis as well as during therapy. This study indicates the presence of both immune-enhancing as well as regulatory responses in HR-NBL patients during (immuno)therapy. Especially the double-edged effects observed in IL-2-containing IT cycles are interesting, as this potentially explains the absence of clinical benefit of IL-2 addition to IT cycles. This suggests that there is a need to combine anti-GD2 with more specific immune-enhancing strategies to improve IT outcome in HR-NBL.

Monitoring Immune Responses in Neuroblastoma Patients during Therapy.

Neuroblastoma (NBL) is the most common extracranial solid tumor in childhood. Despite intense treatment, children with this high-risk disease have a poor prognosis. Immunotherapy showed a significant improvement in event-free survival in high-risk NBL patients receiving chimeric anti-GD2 in combination with cytokines and isotretinoin after myeloablative consolidation therapy. However, response to immunotherapy varies widely, and often therapy is stopped due to severe toxicities. Objective markers that help to predict which patients will respond or develop toxicity to a certain treatment are lacking. Immunotherapy guided via immune monitoring protocols will help to identify responders as early as possible, to decipher the immune response at play, and to adjust or develop new treatment strategies. In this review, we summarize recent studies investigating frequency and phenotype of immune cells in NBL patients prior and during current treatment protocols and highlight how these findings are related to clinical outcome. In addition, we discuss potential targets to improve immunogenicity and strategies that may help to improve therapy efficacy. We conclude that immune monitoring during therapy of NBL patients is essential to identify predictive biomarkers to guide patients towards effective treatment, with limited toxicities and optimal quality of life.

Predictors for Autoimmune Cytopenias after Allogeneic Hematopoietic Cell Transplantation in Children.

Development of autoimmune cytopenia (AIC) after allogeneic hematopoietic cell transplantation (HCT) is a serious complication requiring urgent intensification of immunosuppressive therapy. The pathophysiology and predictors of AIC are not completely understood. In this retrospective cohort analysis of 380 pediatric patients, we evaluated the incidence, outcomes, and related various variables, including immune reconstitution markers to AIC. Three hundred eighty patients (median age, 7.4 years; range, .1 to 22.7) were included, of which 30 patients (7.8%) developed AIC in 1 (n = 6), 2 (n = 6), or 3 (n = 16) cell lineages at a median of 133 days (range, 46 to 445) after HCT. Using multivariate analysis we found that chemo-naivety before HCT, acute graft-versus-host disease (aGVHD) grades II to IV, and serotherapy were associated with the development of AIC. Development of AIC was preceded by increased levels of IgM, IgA, and IgG. Immune profiles of total absolute lymphocytes were very similar between AIC patients and control subjects. However, CD3-CD16+CD56+ natural killer cells, CD3+ T cells, CD3+CD4+ T cell subset, and CD3+CD8+ T cell subset were lower in AIC patients. Overall survival was good, at 83% (similar between AIC patients and control subjects). In conclusion, we identified chemo-naivety before HCT, preceding aGVHD grades II to IV, and serotherapy as predictors for development of AIC. Increasing levels of IgM, IgA, and IgG preceded AIC development. These data provide clues to further study the biology of AIC.

A "No-Touch" Antibody-Staining Method of Adherent Cells for High-Throughput Flow Cytometry in 384-Well Microplate Format for Cell-Based Drug Library Screening.

In the last decade, screening compound libraries on live cells has become an important step in drug discovery. The abundance of compounds in these libraries requires effective high-throughput (HT) analyzing methods. Although current cell-based assay protocols are suitable for HT analyses, the analysis itself is often restrained to simple, singular outcomes. Incorporation of HT samplers on flow cytometers has provided an interesting approach to increase the number of measurable parameters and increase the sensitivity and specificity of analyses. Nonetheless, to date, the labor intensive and time-consuming strategies to detach and stain adherent cells before flow cytometric analysis has restricted use of HT flow cytometry (HTFC) to suspension cells. We have developed a universal "no-touch" HTFC antibody staining protocol in 384-well microplates to bypass washing and centrifuging steps of conventional flow cytometry protocols. Optimizing culture conditions, cell-detachment and staining strategies in 384-well microplates resulted in an HTFC protocol with an optimal stain index with minimal background staining. The method has been validated using six adherent cell lines and simultaneous staining of four parameters. This HT screening protocol allows for effective monitoring of multiple cellular markers simultaneously, thereby increasing informativity and cost-effectiveness of drug screening. © 2019 The Authors. Cytometry Part A published by Wiley Periodicals LLC. on behalf of International Society for Advancement of Cytometry.

Quantification of total dinutuximab concentrations in neuroblastoma patients with liquid chromatography tandem mass spectrometry.

Neuroblastoma is one of the most commonly found solid tumors in children. The monoclonal antibody dinutuximab (DNX) targets the sialic acid-containing glycosphingolipid GD2 expressed on almost all neuroblastoma tumor cells and induces cell lysis. However, the expression of GD2 is not limited to tumor cells only, but is also present on central nerve tissue and peripheral nerve cells explaining dinutuximab toxicity. The most common adverse reactions are pain and discomfort, which may lead to discontinuation of the treatment. Furthermore, there is little to no data available on exposure and effect relationships of dinutuximab. We, therefore, developed an easy method in order to quantify dinutuximab levels in human plasma. Ammonium sulfate (AS) was used to precipitate all immunoglobulins (IgGs) in human plasma. After centrifugation, supernatant containing albumin was decanted and the precipitated IgG fraction was re-dissolved in a buffer containing 0.5% sodium dodecyl sulfate (SDS). Samples were then reduced, alkylated, and digested with trypsin. Finally, a signature peptide in complementarity determining region 1 of DNX heavy chain was quantified on LC-MS/MS using a stable isotopically labeled peptide as internal standard. AS purification efficiently removed 97.5% of the albumin fraction in the supernatant layer. The validation performed on DNX showed that within-run and between-run coefficients of variation (CV) for lower limit of quantification (LLOQ) were 5.5 and 1.4%, respectively. The overall CVs for quality control (QC) low, QC med, and QC high levels were < 5%. Linearity in the range 1-32 mg/L was excellent (r2 > 0.999). Selectivity, stability, and matrix effect were in concordance with EMA guidelines. In conclusion, a method to quantify DNX in human plasma was successfully developed. In addition, the high and robust process efficiency enabled the utilization of a stable isotopically labeled (SIL) peptide instead of SIL DNX, which was commercially unavailable. Graphical abstract.