Precision Medicine for Childhood Cancer: Current Limitations and Future Perspectives.

Greater collaboration needed to realize potential of molecular profiling initiatives for pediatric cancers.

Combination Therapies Targeting ALK-aberrant Neuroblastoma in Preclinical Models.

PURPOSE: ALK-activating mutations are identified in approximately 10% of newly diagnosed neuroblastomas and ALK amplifications in a further 1%-2% of cases. Lorlatinib, a third-generation anaplastic lymphoma kinase (ALK) inhibitor, will soon be given alongside induction chemotherapy for children with ALK-aberrant neuroblastoma. However, resistance to single-agent treatment has been reported and therapies that improve the response duration are urgently required. We studied the preclinical combination of lorlatinib with chemotherapy, or with the MDM2 inhibitor, idasanutlin, as recent data have suggested that ALK inhibitor resistance can be overcome through activation of the p53-MDM2 pathway. EXPERIMENTAL DESIGN: We compared different ALK inhibitors in preclinical models prior to evaluating lorlatinib in combination with chemotherapy or idasanutlin. We developed a triple chemotherapy (CAV: cyclophosphamide, doxorubicin, and vincristine) in vivo dosing schedule and applied this to both neuroblastoma genetically engineered mouse models (GEMM) and patient-derived xenografts (PDX). RESULTS: Lorlatinib in combination with chemotherapy was synergistic in immunocompetent neuroblastoma GEMM. Significant growth inhibition in response to lorlatinib was only observed in the ALK-amplified PDX model with high ALK expression. In this PDX, lorlatinib combined with idasanutlin resulted in complete tumor regression and significantly delayed tumor regrowth. CONCLUSIONS: In our preclinical neuroblastoma models, high ALK expression was associated with lorlatinib response alone or in combination with either chemotherapy or idasanutlin. The synergy between MDM2 and ALK inhibition warrants further evaluation of this combination as a potential clinical approach for children with neuroblastoma.

Liquid biopsy for children with central nervous system tumours: Clinical integration and technical considerations.

Circulating cell-free DNA (cfDNA) analysis has the potential to revolutionise the care of patients with cancer and is already moving towards standard of care in some adult malignancies. Evidence for the utility of cfDNA analysis in paediatric cancer patients is also accumulating. In this review we discuss the limitations of blood-based assays in patients with brain tumours and describe the evidence supporting cerebrospinal fluid (CSF) cfDNA analysis. We make recommendations for CSF cfDNA processing to aid the standardisation and technical validation of future assays. We discuss the considerations for interpretation of cfDNA analysis and highlight promising future directions. Overall, cfDNA profiling shows great potential as an adjunct to the analysis of biopsy tissue in paediatric cancer patients, with the potential to provide a genetic molecular profile of the tumour when tissue biopsy is not feasible. However, to fully realise the potential of cfDNA analysis for children with brain tumours larger prospective studies incorporating serial CSF sampling are required.

Molecular Characterization of Circulating Tumor DNA in Pediatric Rhabdomyosarcoma: A Feasibility Study.

PURPOSE: Rhabdomyosarcomas (RMS) are rare neoplasms affecting children and young adults. Efforts to improve patient survival have been undermined by a lack of suitable disease markers. Plasma circulating tumor DNA (ctDNA) has shown promise as a potential minimally invasive biomarker and monitoring tool in other cancers; however, it remains underexplored in RMS. We aimed to determine the feasibility of identifying and quantifying ctDNA in plasma as a marker of disease burden and/or treatment response using blood samples from RMS mouse models and patients. METHODS: We established mouse models of RMS and applied quantitative polymerase chain reaction (PCR) and droplet digital PCR (ddPCR) to detect ctDNA within the mouse plasma. Potential driver mutations, copy-number alterations, and DNA breakpoints associated with PAX3/7-FOXO1 gene fusions were identified in the RMS samples collected at diagnosis. Patient-matched plasma samples collected from 28 patients with RMS before, during, and after treatment were analyzed for the presence of ctDNA via ddPCR, panel sequencing, and/or whole-exome sequencing. RESULTS: Human tumor-derived DNA was detectable in plasma samples from mouse models of RMS and correlated with tumor burden. In patients, ctDNA was detected in 14/18 pretreatment plasma samples with ddPCR and 7/7 cases assessed by sequencing. Levels of ctDNA at diagnosis were significantly higher in patients with unfavorable tumor sites, positive nodal status, and metastasis. In patients with serial plasma samples (n = 18), fluctuations in ctDNA levels corresponded to treatment response. CONCLUSION: Comprehensive ctDNA analysis combining high sensitivity and throughput can identify key molecular drivers in RMS models and patients, suggesting potential as a minimally invasive biomarker. Preclinical assessment of treatments using mouse models and further patient testing through prospective clinical trials are now warranted.

Circulating tumour DNA sequencing to determine therapeutic response and identify tumour heterogeneity in patients with paediatric solid tumours.

OBJECTIVE: Clinical diagnostic sequencing of circulating tumour DNA (ctDNA) is well advanced for adult patients, but application to paediatric cancer patients lags behind. METHODS: To address this, we have developed a clinically relevant (67 gene) NGS capture panel and accompanying workflow that enables sensitive and reliable detection of low-frequency genetic variants in cell-free DNA (cfDNA) from children with solid tumours. We combined gene panel sequencing with low pass whole-genome sequencing of the same library to inform on genome-wide copy number changes in the blood. RESULTS: Analytical validity was evaluated using control materials, and the method was found to be highly sensitive (0.96 for SNVs and 0.97 for INDEL), specific (0.82 for SNVs and 0.978 for INDEL), repeatable (>0.93 [95% CI: 0.89-0.95]) and reproducible (>0.87 [95% CI: 0.87-0.95]). Potential for clinical application was demonstrated in 39 childhood cancer patients with a spectrum of solid tumours in which the single nucleotide variants expected from tumour sequencing were detected in cfDNA in 94.4% (17/18) of cases with active extracranial disease. In 13 patients, where serial samples were available, we show a close correlation between events detected in cfDNA and treatment response, demonstrate that cfDNA analysis could be a useful tool to monitor disease progression, and show cfDNA sequencing has the potential to identify targetable variants that were not detected in tumour samples. CONCLUSIONS: This is the first pan-cancer DNA sequencing panel that we know to be optimised for cfDNA in children for blood-based molecular diagnostics in paediatric solid tumours.

Genomic Classification and Clinical Outcome in Rhabdomyosarcoma: A Report From an International Consortium.

PURPOSE: Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood. Despite aggressive therapy, the 5-year survival rate for patients with metastatic or recurrent disease remains poor, and beyond PAX-FOXO1 fusion status, no genomic markers are available for risk stratification. We present an international consortium study designed to determine the incidence of driver mutations and their association with clinical outcome. PATIENTS AND METHODS: Tumor samples collected from patients enrolled on Children's Oncology Group trials (1998-2017) and UK patients enrolled on malignant mesenchymal tumor and RMS2005 (1995-2016) trials were subjected to custom-capture sequencing. Mutations, indels, gene deletions, and amplifications were identified, and survival analysis was performed. RESULTS: DNA from 641 patients was suitable for analyses. A median of one mutation was found per tumor. In FOXO1 fusion-negative cases, mutation of any RAS pathway member was found in > 50% of cases, and 21% had no putative driver mutation identified. BCOR (15%), NF1 (15%), and TP53 (13%) mutations were found at a higher incidence than previously reported and TP53 mutations were associated with worse outcomes in both fusion-negative and FOXO1 fusion-positive cases. Interestingly, mutations in RAS isoforms predominated in infants < 1 year (64% of cases). Mutation of MYOD1 was associated with histologic patterns beyond those previously described, older age, head and neck primary site, and a dismal survival. Finally, we provide a searchable companion database (ClinOmics), containing all genomic variants, and clinical annotation including survival data. CONCLUSION: This is the largest genomic characterization of clinically annotated rhabdomyosarcoma tumors to date and provides prognostic genetic features that refine risk stratification and will be incorporated into prospective trials.

Frequency and Prognostic Impact of ALK Amplifications and Mutations in the European Neuroblastoma Study Group (SIOPEN) High-Risk Neuroblastoma Trial (HR-NBL1).

PURPOSE: In neuroblastoma (NB), the ALK receptor tyrosine kinase can be constitutively activated through activating point mutations or genomic amplification. We studied ALK genetic alterations in high-risk (HR) patients on the HR-NBL1/SIOPEN trial to determine their frequency, correlation with clinical parameters, and prognostic impact. MATERIALS AND METHODS: Diagnostic tumor samples were available from 1,092 HR-NBL1/SIOPEN patients to determine ALK amplification status (n = 330), ALK mutational profile (n = 191), or both (n = 571). RESULTS: Genomic ALK amplification (ALKa) was detected in 4.5% of cases (41 out of 901), all except one with MYCN amplification (MNA). ALKa was associated with a significantly poorer overall survival (OS) (5-year OS: ALKa [n = 41] 28% [95% CI, 15 to 42]; no-ALKa [n = 860] 51% [95% CI, 47 to 54], [P < .001]), particularly in cases with metastatic disease. ALK mutations (ALKm) were detected at a clonal level (> 20% mutated allele fraction) in 10% of cases (76 out of 762) and at a subclonal level (mutated allele fraction 0.1%-20%) in 3.9% of patients (30 out of 762), with a strong correlation between the presence of ALKm and MNA (P < .001). Among 571 cases with known ALKa and ALKm status, a statistically significant difference in OS was observed between cases with ALKa or clonal ALKm versus subclonal ALKm or no ALK alterations (5-year OS: ALKa [n = 19], 26% [95% CI, 10 to 47], clonal ALKm [n = 65] 33% [95% CI, 21 to 44], subclonal ALKm (n = 22) 48% [95% CI, 26 to 67], and no alteration [n = 465], 51% [95% CI, 46 to 55], respectively; P = .001). Importantly, in a multivariate model, involvement of more than one metastatic compartment (hazard ratio [HR], 2.87; P < .001), ALKa (HR, 2.38; P = .004), and clonal ALKm (HR, 1.77; P = .001) were independent predictors of poor outcome. CONCLUSION: Genetic alterations of ALK (clonal mutations and amplifications) in HR-NB are independent predictors of poorer survival. These data provide a rationale for integration of ALK inhibitors in upfront treatment of HR-NB with ALK alterations.

The Promise of Patient-Derived Preclinical Models to Accelerate the Implementation of Personalised Medicine for Children with Neuroblastoma.

Patient-derived preclinical models are now a core component of cancer research and have the ability to drastically improve the predictive power of preclinical therapeutic studies. However, their development and maintenance can be challenging, time consuming, and expensive. For neuroblastoma, a developmental malignancy of the neural crest, it is possible to establish patient-derived models as xenografts in mice and zebrafish, and as spheroids and organoids in vitro. These varied approaches have contributed to comprehensive packages of preclinical evidence in support of new therapeutics for neuroblastoma. We discuss here the ethical and technical considerations for the creation of patient-derived models of neuroblastoma and how their use can be optimized for the study of tumour evolution and preclinical therapies. We also discuss how neuroblastoma patient-derived models might become avatars for personalised medicine for children with this devastating disease.

Therapeutic vulnerabilities in the DNA damage response for the treatment of ATRX mutant neuroblastoma.

BACKGROUND: In neuroblastoma, genetic alterations in ATRX, define a distinct poor outcome patient subgroup. Despite the need for new therapies, there is a lack of available models and a dearth of pre-clinical research. METHODS: To evaluate the impact of ATRX loss of function (LoF) in neuroblastoma, we utilized CRISPR-Cas9 gene editing to generate neuroblastoma cell lines isogenic for ATRX. We used these and other models to identify therapeutically exploitable synthetic lethal vulnerabilities associated with ATRX LoF. FINDINGS: In isogenic cell lines, we found that ATRX inactivation results in increased DNA damage, homologous recombination repair (HRR) defects and impaired replication fork processivity. In keeping with this, high-throughput compound screening showed selective sensitivity in ATRX mutant cells to multiple PARP inhibitors and the ATM inhibitor KU60019. ATRX mutant cells also showed selective sensitivity to the DNA damaging agents, sapacitabine and irinotecan. HRR deficiency was also seen in the ATRX deleted CHLA-90 cell line, and significant sensitivity demonstrated to olaparib/irinotecan combination therapy in all ATRX LoF models. In-vivo sensitivity to olaparib/irinotecan was seen in ATRX mutant but not wild-type xenografts. Finally, sustained responses to olaparib/irinotecan therapy were seen in an ATRX deleted neuroblastoma patient derived xenograft. INTERPRETATION: ATRX LoF results in specific DNA damage repair defects that can be therapeutically exploited. In ATRX LoF models, preclinical sensitivity is demonstrated to olaparib and irinotecan, a combination that can be rapidly translated into the clinic. FUNDING: This work was supported by Christopher's Smile, Neuroblastoma UK, Cancer Research UK, and the Royal Marsden Hospital NIHR BRC.

Accelerating drug development for neuroblastoma: Summary of the Second Neuroblastoma Drug Development Strategy forum from Innovative Therapies for Children with Cancer and International Society of Paediatric Oncology Europe Neuroblastoma.

Only one class of targeted agents (anti-GD2 antibodies) has been incorporated into front-line therapy for neuroblastoma since the 1980s. The Neuroblastoma New Drug Development Strategy (NDDS) initiative commenced in 2012 to accelerate the development of new drugs for neuroblastoma. Advances have occurred, with eight of nine high-priority targets being evaluated in paediatric trials including anaplastic lymphoma kinase inhibitors being investigated in front-line, but significant challenges remain. This article reports the conclusions of the second NDDS forum, which expanded across the Atlantic to further develop the initiative. Pre-clinical and clinical data for 40 genetic targets and mechanisms of action were prioritised and drugs were identified for early-phase trials. Strategies to develop drugs targeting TERT, telomere maintenance, ATRX, alternative lengthening of telomeres (ALT), BRIP1 and RRM2 as well as direct targeting of MYCN are high priority and should be championed for drug discovery. Promising pre-clinical data suggest that targeting of ALT by ATM or PARP inhibition may be potential strategies. Drugs targeting CDK2/9, CDK7, ATR and telomere maintenance should enter paediatric clinical development rapidly. Optimising the response to anti-GD2 by combinations with chemotherapy, targeted agents and other immunological targets are crucial. Delivering this strategy in the face of small patient cohorts, genomically defined subpopulations and a large number of permutations of combination trials, demands even greater international collaboration. In conclusion, the NDDS provides an internationally agreed, biologically driven selection of prioritised genetic targets and drugs. Improvements in the strategy for conducting trials in neuroblastoma will accelerate bringing these new drugs more rapidly to front-line therapy.

MYCN expression induces replication stress and sensitivity to PARP inhibition in neuroblastoma.

This study investigates the influence expression of the MYCN oncogene has on the DNA damage response, replication fork progression and sensitivity to PARP inhibition in neuroblastoma. In a panel of neuroblastoma cell lines, MYCN amplification or MYCN expression resulted in increased cell death in response to a range of PARP inhibitors (niraparib, veliparib, talazoparib and olaparib) compared to the response seen in non-expressing/amplified cells. MYCN expression slowed replication fork speed and increased replication fork stalling, an effect that was amplified by PARP inhibition or PARP1 depletion. Increased DNA damage seen was specifically induced in S-phase cells. Importantly, PARP inhibition caused a significant increase in the survival of mice bearing MYCN expressing tumours in a transgenic murine model of MYCN expressing neuroblastoma. Olaparib also sensitized MYCN expressing cells to camptothecin- and temozolomide-induced cell death to a greater degree than non-expressing cells. In summary, MYCN expression leads to increased replication stress in neuroblastoma cells. This effect is exaggerated by inhibition of PARP, resulting in S-phase specific DNA damage and ultimately increased tumour cell death. PARP inhibition alone or in combination with classical chemotherapeutics is therefore a potential therapeutic strategy for neuroblastoma and may be more effective in MYCN expressing tumours.

Realizing Relational Preferences Through Transforming Interpersonal Patterns.

Family therapy has often been conceptualized as a conversational process whereby therapists and clients generate new meanings. Based on a 3-year study of conversational practices observable in successful family therapy processes of Chilean families with a child/adolescent who is engaged in disruptive behaviors, we looked for clinical examples of Transforming Interpersonal Patterns (TIPs). TIPs are a key aspect of the IPscope, a framework we used to explore the meaning-making processes in family therapy. TIPs constitute a novel approach to explore therapeutic processes by identifying empirically traceable conversational practices involved in generating "new meanings." TIPs are involved in bringing forth and discursively articulating ("talking-into-being") clients' preferred ways of relating and living (i.e., relational preferences or RPs). We analyze conversational data from successful family therapy sessions/treatments, and present an emergent model of five categories of conversational practices making up TIPs, namely: Preparatory TIPs, Identifier TIPs, Tracker TIPs, Transformer TIPs, and Consolidator TIPs. We have called them "realizers" because these conversational practices help families talk-into-being (or "make real") particular relational preferences. We also offer user-friendly descriptors of realizers' subcategories (e.g., Measuring TIPs) which may help practitioners to recognize, learn, and perform these conversational invitations. Theoretical consequences and future lines of research are discussed.

La terapia familiar generalmente se ha conceptualizado como un proceso conversacional por medio del cual los terapeutas y los pacientes generan nuevos significados. Basándose en un estudio de tres años de prácticas conversacionales observables en procesos satisfactorios de terapia familiar de familias chilenas con un niño/adolescente que tiene comportamientos disruptivos, buscamos ejemplos clínicos de patrones interpersonales transformadores (PIT). Estos patrones son un aspecto clave del "IPscope" o instrumento de evaluación de los patrones interpersonales (Tomm, St. George, Wulff, & Strong, 2014), un marco que usamos para analizar los procesos de creación de significado en la terapia familiar. Los patrones interpersonales transformadores constituyen un enfoque innovador para analizar los procesos terapéuticos mediante el reconocimiento de prácticas conversacionales fáciles de seguir empíricamente que participan en la generación de "significados nuevos". Los patrones interpersonales transformadores intervienen en la presentación y la articulación discursiva ("convencer de crear") de las manersa preferidas de los pacientes de relacionarse y vivir (p. ej.: preferencias relacionales o PR). Analizamos datos conversacionales de sesiones/tratamientos satisfactorios de terapia familiar y presentamos un modelo emergente de cinco categorías de prácticas conversacionales que constituyen patrones interpersonales transformadores, por ejemplo: PIT preparatorios, PIT identificadores, PIT localizadores, PIT transformadores y PIT consolidadores. Los hemos llamado "realizadores" porque estas prácticas conversacionales ayudan a las familias a convencerlas de crear (o a "hacer realidad") preferencias relacionales particulares. También ofrecemos descriptores fáciles de usar de las subcategorías de los realizadores (p. ej.: PIT de medición) que pueden ayudar a los profesionales a reconocer, aprender y llevar a cabo estas invitaciones conversacionales. Se debaten las consecuencias teóricas y las futuras líneas de investigación.

A tailored molecular profiling programme for children with cancer to identify clinically actionable genetic alterations.

BACKGROUND: For children with cancer, the clinical integration of precision medicine to enable predictive biomarker-based therapeutic stratification is urgently needed. METHODS: We have developed a hybrid-capture next-generation sequencing (NGS) panel, specifically designed to detect genetic alterations in paediatric solid tumours, which gives reliable results from as little as 50 ng of DNA extracted from formalin-fixed paraffin-embedded (FFPE) tissue. In this study, we offered an NGS panel, with clinical reporting via a molecular tumour board for children with solid tumours. Furthermore, for a cohort of 12 patients, we used a circulating tumour DNA (ctDNA)-specific panel to sequence ctDNA from matched plasma samples and compared plasma and tumour findings. RESULTS: A total of 255 samples were submitted from 223 patients for the NGS panel. Using FFPE tissue, 82% of all submitted samples passed quality control for clinical reporting. At least one genetic alteration was detected in 70% of sequenced samples. The overall detection rate of clinically actionable alterations, defined by modified OncoKB criteria, for all sequenced samples was 51%. A total of 8 patients were sequenced at different stages of treatment. In 6 of these, there were differences in the genetic alterations detected between time points. Sequencing of matched ctDNA in a cohort of extracranial paediatric solid tumours also identified a high detection rate of somatic alterations in plasma. CONCLUSION: We demonstrate that tailored clinical molecular profiling of both tumour DNA and plasma-derived ctDNA is feasible for children with solid tumours. Furthermore, we show that a targeted NGS panel-based approach can identify actionable genetic alterations in a high proportion of patients.

In Vivo Modeling of Chemoresistant Neuroblastoma Provides New Insights into Chemorefractory Disease and Metastasis.

Neuroblastoma is a pediatric cancer that is frequently metastatic and resistant to conventional treatment. In part, a lack of natively metastatic, chemoresistant in vivo models has limited our insight into the development of aggressive disease. The Th-MYCN genetically engineered mouse model develops rapidly progressive chemosensitive neuroblastoma and lacks clinically relevant metastases. To study tumor progression in a context more reflective of clinical therapy, we delivered multicycle treatment with cyclophosphamide to Th-MYCN mice, individualizing therapy using MRI, to generate the Th-MYCN CPM32 model. These mice developed chemoresistance and spontaneous bone marrow metastases. Tumors exhibited an altered immune microenvironment with increased stroma and tumor-associated fibroblasts. Analysis of copy number aberrations revealed genomic changes characteristic of human MYCN-amplified neuroblastoma, specifically copy number gains at mouse chromosome 11, syntenic with gains on human chromosome 17q. RNA sequencing revealed enriched expression of genes associated with 17q gain and upregulation of genes associated with high-risk neuroblastoma, such as the cell-cycle regulator cyclin B1-interacting protein 1 (Ccnb1ip1) and thymidine kinase (TK1). The antiapoptotic, prometastatic JAK-STAT3 pathway was activated in chemoresistant tumors, and treatment with the JAK1/JAK2 inhibitor CYT387 reduced progression of chemoresistant tumors and increased survival. Our results highlight that under treatment conditions that mimic chemotherapy in human patients, Th-MYCN mice develop genomic, microenvironmental, and clinical features reminiscent of human chemorefractory disease. The Th-MYCN CPM32 model therefore is a useful tool to dissect in detail mechanisms that drive metastasis and chemoresistance, and highlights dysregulation of signaling pathways such as JAK-STAT3 that could be targeted to improve treatment of aggressive disease. SIGNIFICANCE: An in vivo mouse model of high-risk treatment-resistant neuroblastoma exhibits changes in the tumor microenvironment, widespread metastases, and sensitivity to JAK1/2 inhibition.

Accelerating drug development for neuroblastoma - New Drug Development Strategy: an Innovative Therapies for Children with Cancer, European Network for Cancer Research in Children and Adolescents and International Society of Paediatric Oncology Europe Neuroblastoma project.

INTRODUCTION: Neuroblastoma, the commonest paediatric extra-cranial tumour, remains a leading cause of death from cancer in children. There is an urgent need to develop new drugs to improve cure rates and reduce long-term toxicity and to incorporate molecularly targeted therapies into treatment. Many potential drugs are becoming available, but have to be prioritised for clinical trials due to the relatively small numbers of patients. Areas covered: The current drug development model has been slow, associated with significant attrition, and few new drugs have been developed for neuroblastoma. The Neuroblastoma New Drug Development Strategy (NDDS) has: 1) established a group with expertise in drug development; 2) prioritised targets and drugs according to tumour biology (target expression, dependency, pre-clinical data; potential combinations; biomarkers), identifying as priority targets ALK, MEK, CDK4/6, MDM2, MYCN (druggable by BET bromodomain, aurora kinase, mTORC1/2) BIRC5 and checkpoint kinase 1; 3) promoted clinical trials with target-prioritised drugs. Drugs showing activity can be rapidly transitioned via parallel randomised trials into front-line studies. Expert opinion: The Neuroblastoma NDDS is based on the premise that optimal drug development is reliant on knowledge of tumour biology and prioritisation. This approach will accelerate neuroblastoma drug development and other poor prognosis childhood malignancies.

Development of a targeted sequencing approach to identify prognostic, predictive and diagnostic markers in paediatric solid tumours.

The implementation of personalised medicine in childhood cancers has been limited by a lack of clinically validated multi-target sequencing approaches specific for paediatric solid tumours. In order to support innovative clinical trials in high-risk patients with unmet need, we have developed a clinically relevant targeted sequencing panel spanning 311 kb and comprising 78 genes involved in childhood cancers. A total of 132 samples were used for the validation of the panel, including Horizon Discovery cell blends (n=4), cell lines (n=15), formalin-fixed paraffin embedded (FFPE, n=83) and fresh frozen tissue (FF, n=30) patient samples. Cell blends containing known single nucleotide variants (SNVs, n=528) and small insertion-deletions (indels n=108) were used to define panel sensitivities of ≥98% for SNVs and ≥83% for indels [95% CI] and panel specificity of ≥98% [95% CI] for SNVs. FFPE samples performed comparably to FF samples (n=15 paired). Of 95 well-characterised genetic abnormalities in 33 clinical specimens and 13 cell lines (including SNVs, indels, amplifications, rearrangements and chromosome losses), 94 (98.9%) were detected by our approach. We have validated a robust and practical methodology to guide clinical management of children with solid tumours based on their molecular profiles. Our work demonstrates the value of targeted gene sequencing in the development of precision medicine strategies in paediatric oncology.

Individualized 131I-mIBG therapy in the management of refractory and relapsed neuroblastoma.

OBJECTIVE: Iodine-131-labelled meta-iodobenzylguanidine (I-mIBG) therapy is an established treatment modality for relapsed/refractory neuroblastoma, most frequently administered according to fixed or weight-based criteria. We evaluate response and toxicity following a dosimetry-based, individualized approach. MATERIALS AND METHODS: A review of 44 treatments in 25 patients treated with I-mIBG therapy was performed. Patients received I-mIBG therapy following relapse (n=9), in refractory disease (n=12), or with surgically unresectable disease despite conventional treatment (n=4). Treatment schedule (including mIBG dose and number of administrations) was individualized according to the clinical status of the patient and dosimetry data from either a tracer study or previous administrations. Three-dimensional tumour dosimetry was also performed for eight patients. RESULTS: The mean administered activity was 11089±7222 MBq and the mean whole-body dose for a single administration was 1.79±0.57 Gy. Tumour-absorbed doses varied considerably (3.70±3.37 mGy/MBq). CTCAE grade 3/4 neutropenia was documented following 82% treatments and grade 3/4 thrombocytopenia following 71% treatments. Further acute toxicity was found in 49% of patients. All acute toxicities resolved with appropriate therapy. The overall response rate was 58% (complete or partial response), with a further 29% of patients having stable disease. CONCLUSION: A highly personalized approach combining patient-specific dosimetry and clinical judgement enables delivery of high activities that can be tolerated by patients, particularly with stem cell support. We report excellent response rates and acceptable toxicity following individualized I-mIBG therapy.

Docetaxel in the treatment of children with refractory or relapsed hepatoblastoma.

We report on the use of single-agent docetaxel (100 mg/m(2) in children >10 kg, 3.3 mg/kg in children <10 kg), given as a 1-hour infusion at 21-day intervals in 5 children with relapsed or refractory hepatoblastoma. One patient achieved complete remission of pulmonary metastases after 2 courses of docetaxel and remains well 10 years later, after completion of 13 courses of docetaxel and whole-lung radiotherapy. One patient showed a partial response to docetaxel based on α-fetoprotein measurements. Docetaxel shows some activity in progressive hepatoblastoma in this small case series and is a potential drug for future study in this disease.