Case report: Therapy-related myeloid neoplasms in three pediatric cases with medulloblastoma

Introduction

Medulloblastoma is the most common malignant brain tumor in children, often requiring intensive multimodal therapy, including chemotherapy with alkylating agents. However, therapy-related complications, such as therapy-related myeloid neoplasms (t-MNs), can arise, particularly in patients with genetic predisposition syndromes. This case report presents three pediatric cases of medulloblastoma with subsequent development of t-MNs, highlighting the potential role of genetic predisposition and the importance of surveillance for hematological abnormalities in long-term survivors.

Case presentation

We describe three cases of pediatric medulloblastoma who developed t-MNs after receiving chemotherapy, including alkylating agents. Two of the patients had underlying genetic predisposition syndromes (TP53 pathologic variants). The latency period between initial diagnosis of medulloblastoma and the development of secondary cancer varied among the cases, ranging from 17 to 65 months. The three cases eventually succumbed from secondary malignancy, therapy-related complications and progression of primary disease, respectively.

Conclusions

This report highlights the potential association between genetic predisposition syndromes and the development of therapy-related myeloid neoplasms in pediatric medulloblastoma survivors. It underscores the importance of surveillance for hematological abnormalities among such patients.

Genome-Wide DNA Methylation Profiling as Frontline Diagnostics for Central Nervous System Embryonal Tumors in Hong Kong

This paper examines the link between CNS tumor biology and heterogeneity and the use of genome-wide DNA methylation profiling as a clinical diagnostic platform. CNS tumors are the most common solid tumors in children, and their prognosis remains poor. This study retrospectively analyzed pediatric patients with CNS embryonal tumors in Hong Kong between 1999 and 2017, using data from the territory-wide registry and available formalin-fixed paraffin-embedded tumor tissue. After processing archival tumor tissue via DNA extraction, quantification, and methylation profiling, the data were analyzed by using the web-based DKFZ classifier (Molecular Neuropathology (MNP) 2.0 v11b4) and t-SNE analysis. Methylation profiles were deemed informative in 85 samples. Epigenetic data allowed molecular subgrouping and confirmed diagnosis in 65 samples, verified histologic diagnosis in 8, and suggested an alternative diagnosis in 12. This study demonstrates the potential of DNA methylation profiling in characterizing pediatric CNS embryonal tumors in a large cohort from Hong Kong, which should enable regional and international collaboration in future pediatric neuro-oncology research.

Incidence and Predictors for Oncologic Etiologies in Chinese Children with Pituitary Stalk Thickening

BACKGROUND

With the increasing use of magnetic resonance imaging (MRI) in the evaluation of children with endocrine disorders, pituitary stalk thickening (PST) poses a clinical conundrum due to the potential for underlying neoplasms and challenges in obtaining a tissue biopsy. The existing literature suggests Langerhans cell histiocytosis (LCH) to be the commonest (16%) oncologic cause for PST, followed by germ cell tumors (GCTs, 13%) (CCLG 2021). As the cancer epidemiology varies according to ethnicity, we present herein the incidence and predictors for oncologic etiologies in Hong Kong Chinese children with PST.

METHODS

Based on a territory-wide electronic database, we reviewed patients aged < 19 years who presented to three referral centers with endocrinopathies between 2010 and 2022. Records for patients who underwent at least one MRI brain/pituitary were examined (n = 1670): those with PST (stalk thickness ≥ 3 mm) were included, while patients with pre-existing cancer, other CNS and extra-CNS disease foci that were diagnostic of the underlying condition were excluded.

RESULTS

Twenty-eight patients (M:F = 10:18) were identified. The median age at diagnosis of PST was 10.9 years (range: 3.8-16.5), with central diabetes insipidus (CDI) and growth hormone deficiency (GHD) being the most frequent presenting endocrine disorders. At a median follow-up of 4.8 years, oncologic diagnoses were made in 14 patients (50%), including 13 GCTs (46%; germinoma = 11, non-germinoma = 2) and one LCH (4%). Among patients with GCTs, 10 were diagnosed based on histology, two by abnormal tumor markers and one by a combination of histology and tumor markers. Three patients with germinoma were initially misdiagnosed as hypophysitis/LCH. The cumulative incidence of oncologic diagnoses was significantly higher in boys and patients with PST at presentation ≥6.5 mm, CDI or ≥2 pituitary hormone deficiencies at presentation and evolving hypopituitarism (all p < 0.05 by log-rank).

CONCLUSIONS

A higher rate of GCTs was observed in Chinese children with endocrinopathy and isolated PST. The predictors identified in this study may guide healthcare providers in Asia in clinical decision making. Serial measurement of tumor markers is essential in management.

DICER1 -Altered Extraovarian Moderately Differentiated Sertoli-Leydig Cell Tumor: Report of a Rare Case

We report an unusual case of a pelvic extraovarian moderately differentiated Sertoli-Leydig cell tumor arising in a 4-yr-old female. The tumor contained a DICER1 pathogenic variant which was absent in the germline ruling out DICER1 syndrome. In reporting this case, we discuss the differential diagnosis and possible histogenesis and review reported cases of extraovarian Sertoli-Leydig cell tumor.

Molecular classification and outcome of children with rare CNS embryonal tumors: results from St. Jude Children's Research Hospital including the multi-center SJYC07 and SJMB03 clinical trials

Methylation profiling has radically transformed our understanding of tumors previously called central nervous system primitive neuro-ectodermal tumors (CNS-PNET). While this marks a momentous step toward defining key differences, reclassification has thrown treatment into disarray. To shed light on response to therapy and guide clinical decision-making, we report outcomes and molecular features of children with CNS-PNETs from two multi-center risk-adapted studies (SJMB03 for patients ≥ 3 years; SJYC07 for patients < 3 years) complemented by a non-protocol institutional cohort. Seventy patients who had a histological diagnosis of CNS-PNET or CNS embryonal tumor from one of the new categories that has supplanted CNS-PNET were included. This cohort was molecularly characterized by DNA methylation profiling (n = 70), whole-exome sequencing (n = 53), RNA sequencing (n = 20), and germline sequencing (n = 28). Clinical characteristics were detailed, and treatment was divided into craniospinal irradiation (CSI)-containing (SJMB03 and SJMB03-like) and CSI-sparing therapy (SJYC07 and SJYC07-like). When the cohort was analyzed in its entirety, no differences were observed in the 5-year survival rates even when CSI-containing therapy was compared to CSI-sparing therapy. However, when analyzed by DNA methylation molecular grouping, significant survival differences were observed, and treatment particulars provided suggestions of therapeutic response. Patients with CNS neuroblastoma with FOXR2 activation (CNS-NB-FOXR2) had a 5-year event-free survival (EFS)/overall survival (OS) of 66.7% ± 19.2%/83.3% ± 15.2%, and CIC rearranged sarcoma (CNS-SARC-CIC) had a 5-year EFS/OS both of 57.1% ± 18.7% with most receiving regimens that contained radiation (focal or CSI) and multidrug chemotherapy. Patients with high-grade neuroepithelial tumor with BCOR alteration (HGNET-BCOR) had abysmal responses to upfront chemotherapy-only regimens (5-year EFS = 0%), but survival extended with salvage radiation after progression [5-year OS = 53.6% ± 20.1%]. Patients with embryonal tumor with multilayered rosettes (ETMR) or high-grade glioma/glioblastoma multiforme (HGG/GBM) did not respond favorably to any modality (5-year EFS/OS = 10.7 ± 5.8%/17.9 ± 7.2%, and 10% ± 9.0%/10% ± 9.0%, respectively). As an accompaniment, we have assembled this data onto an interactive website to allow users to probe and query the cases. By reporting on a carefully matched clinical and molecular cohort, we provide the needed insight for future clinical management.

Pursuing FOXR2-Driven Oncogenesis

FOXR2 encodes a Forkhead-Box transcription factor that has been recently described as a proto-oncogene. In this issue of Cancer Research, Tsai and colleagues present the first pan-cancer study summarizing the prevalence of FOXR2 overexpression beyond rare childhood-onset malignancies. Identification of a previously unknown mechanism of epigenetic activation and the expansion of FOXR2 transcriptional targets enhance the mechanistic understanding of FOXR2-driven malignancy, with the potential to uncover new therapeutic opportunities. See related article by Tsai et al., p. 2980.

Mental health & maltreatment risk of children with special educational needs during COVID-19

BACKGROUND

Children with special educational needs (SEN) are more vulnerable during the COVID-19 pandemic with risk of poor mental wellbeing and child maltreatment.

OBJECTIVE

To examine the impact of COVID-19 on the mental health of children with SEN and their maltreatment risk.

PARTICIPANTS AND SETTING

417 children with SEN studying at special schools and 25,427 children with typical development (TD) studying at mainstream schools completed an online survey in April 2020 in Hong Kong during school closures due to COVID-19.

METHOD

Emotional/behavioural difficulties, quality of life and parental stress of children with SEN were compared with typically developed children using mixed effect model. Linear regression analyses were performed to explore factors associated with child emotional/behavioural difficulties and parental stress during the pandemic. Chi-square test was performed to detect the differences in maltreatment risk before and during COVID-19.

RESULTS

Children with SEN had significantly poorer overall quality of life (68.05 vs 80.65, p < 0.01). 23.5% of children had at least one episode of severe physical assault and 1.9% experienced very severe physical assault during COVID-19. Rates of physical assault increased significantly (59.8% vs. 71.2% p < 0.001) while children with mental disorders had increased risk of severe physical assault comparing to those without mental disorders (RR = 1.58, ꭓ² = 5.19 p = 0.023).

CONCLUSION

Children with SEN had poorer mental health than typically developed children during the COVID-19 pandemic. Maltreatment risk for children with SEN is higher in comparison to pre-COVID-19 era. Surveillance of child maltreatment, continuity of medical and rehabilitation care to support children with SEN are essential during a disease pandemic.

HGG-37. A case ofETV6-NTRK3 fusion driven infantile hemispheric glioma (IHG) with acquired drug resistance against first- and second-generation NTRK-inhibitors

A 3-month-old girl had left cerebral infantile hemispheric glioma (IHG), H3 wild type (wt), Grade IV (WHO2020) with diffuse leptomeningeal and spinal metastasis. Craniotomies were performed twice which achieved partial resection. Histopathology revealed high grade glioma, Ki67 30-40%, mitosis and widespread necrosis. IHC showed H3wt, IDH-, and retained INI-1. RNAseq found ETV6-NTRK3 fusion. She was treated per Baby POG-9233, however after 3 cycles, there was mixed response (static for primary, partial response for metastasis). She had severe developmental delay, right hemiparesis and dysphagia. Aiming for better disease control and potential resectability, we switched to first-generation NTRK-inhibitor, Larotrectinib. MRI at 3 months showed significant interval reduction in tumour size, then became static at 6 months. She was stable with gradual neurological improvement until 10 months after Larotrectinib, there was worsening neurology and imaging confirmed tumour progression with haemorrhage. Craniotomy was performed for haemostasis and tumour debulking. Histopathology showed same IHG with ETV6-NTRK3 fusion. Targeted panel sequencing found NTRK3 p.Gly623Arg mutation, a solvent-front substitution responsible for acquired resistance to first-generation TRK-inhibitors. BRAFV600E and MET amplification were not detected. Larotrectinib was switched to second-generation NTRK-inhibitor, Selitrectinib. MRI at 1 month showed post-operative changes, but disease progressed at 3 months and in an accelerated manner over the course of 10 days while on therapy. Choice of conventional chemotherapy and radiotherapy were discussed, but the girl deteriorated rapidly and deceased (3 months from start of Selitrectinib, 19 months from diagnosis). CONCLUSION: IHG is aggressive with challenging surgery and medical treatment. The use of small molecular inhibitor requires careful consideration, i.e. treatment effect, toxicity and potential acquired drug resistance as showed in this case. For unresectable tumour, it may be inevitable as we also reported a similar case with ROS1 fusion. Access to newer novel agents is difficult while therapeutic effect is uncertain.

PATH-10. Nanopore sequencing reveals novel ALK fusion with interposed element in a neonate with hemispheric glioma

Here we describe the clinical course and unique molecular findings in a female neonate with infantile hemispheric glioma (IHG). The patient presented at the age of 17 days with macrocephaly and suboptimal weight gain. MRI brain revealed an 8.5cm mass over the right frontal region with significant mass effect and entrapment of ventricles. Urgent ventriculoperitoneal shunt insertion and biopsy of the highly vascular lesion was performed. Pathology was compatible with glioblastoma multiforme. Methylation profiling classified the sample as inflammatory tumor tissue (MNP v11b4), while panel RNA-sequencing revealed a fusion event between HMBOX1 and ALK which has not been described in primary CNS tumors. Long-read sequencing with the Nanopore system further revealed complex genomic rearrangement involving an interposed genomic fragment from a third chromosome with validation by Sanger sequencing. Based on an integrated diagnosis of IHG, the patient went on to receive neoadjuvant chemotherapy per the CNS-14 protocol (cyclophosphamide, carboplatin, etoposide) with significant tumor shrinkage. Near total removal of the lesion was achieved after 4 cycles of chemotherapy and adjuvant treatment with 4 additional cycles was given. The patient tolerated therapy well other than self-limiting transaminitis. At the end of treatment, the patient enjoyed intact neurology and satisfactory developmental progress. Our case report illustrates the value a multi-pronged approach to characterizing rare pediatric CNS tumors. The precise delineation of breakpoints in fusion-driven tumors might be of value in the design of cfDNA-based assays. (APYL and CTLC contributed equally to the submission)

ETMR-14. The single-cell landscape of pineoblastoma identifies developmental origins and exposes novel therapeutic vulnerabilities

Pineoblastoma (PB) is a rare and aggressive childhood brain tumor with highly variable age and treatment-associated outcomes. Our recent bulk tumor analyses of DNA methylation and mutational landscapes uncovered four discrete PB molecular subgroups (PB-miRNA1, PB-miRNA2, PB-MYC/FOXR2, and PB-RB), providing a major advance in our understanding of biological and clinical heterogeneity. However, developmental origins of PB subgroup heterogeneity and mechanisms governing how specific genetic alterations promote malignancy remain unknown. To resolve the cellular origins of PB, we assembled a large single-nucleus RNA-sequencing cohort (n=32) of primary PB tumors, including representatives from each subgroup. Transcriptomic analysis identified subgroup-specific gene expression programs driving intra-tumoral heterogeneity. In addition, we discovered substantial differences in the expression of miRNA biogenesis genes between the PB-miRNA1 and PB-miRNA2 subgroups, providing mechanistic support for their distinct subgroup identities despite overlapping driver events. The MYC/FOXR2 subgroup was characterized by over-expression of the FOXR2 proto-oncogene in bulk RNA-seq, which we validated in single-nuclei and identified co-expressed downstream target genes. To map PB subgroups to their putative developmental beginnings, we created a single-cell transcriptional atlas of the murine pineal gland across 11 developmental stages (E11-P21). Trajectory inference within the developing pineal gland revealed a differentiation continuum of early, mid, and mature alpha-/beta pinealocytes. Cross-species correlation and deconvolution identified significant associations between multiple PB subgroups and specific differentiation states of the pinealocyte lineage, suggestive of developmental origins. Characterization of pinealocyte development informed generation of biologically faithful disease models, including a novel genetically engineered mouse model of the PB-RB subgroup. PB-Rb1 mouse tumors were histologically and molecularly validated for their fidelity to human tumor counterparts, exhibiting up-regulation of key pinealocyte lineage markers that are diagnostic in patients. Finally, high-throughput drug screening identified several promising pharmacological candidates that may attenuate consequences of Rb1 deficiency in affected children.

Case Report: Primary Thoracic Low-Grade Fibromyxoid Sarcoma in a Young Girl Presenting With Mediastinal Mass Syndrome

Low-grade fibromyxoid sarcomas (LGFMSs) are typically adult-onset tumors that arise from the extremities. Here, we report an exceptional case of primary thoracic LGFMS in an 8-year-old girl that resulted in mediastinal syndrome. In reporting this case, we discuss the clinical challenges, role of molecular profiling and review reported cases of pediatric thoracic LGFMSs.

Serial assessment of measurable residual disease in medulloblastoma liquid biopsies

Nearly one-third of children with medulloblastoma, a malignant embryonal tumor of the cerebellum, succumb to their disease. Conventional response monitoring by imaging and cerebrospinal fluid (CSF) cytology remains challenging, and a marker for measurable residual disease (MRD) is lacking. Here, we show the clinical utility of CSF-derived cell-free DNA (cfDNA) as a biomarker of MRD in serial samples collected from children with medulloblastoma (123 patients, 476 samples) enrolled on a prospective trial. Using low-coverage whole-genome sequencing, tumor-associated copy-number variations in CSF-derived cfDNA are investigated as an MRD surrogate. MRD is detected at baseline in 85% and 54% of patients with metastatic and localized disease, respectively. The number of MRD-positive patients declines with therapy, yet those with persistent MRD have significantly higher risk of progression. Importantly, MRD detection precedes radiographic progression in half who relapse. Our findings advocate for the prospective assessment of CSF-derived liquid biopsies in future trials for medulloblastoma.

Early Development of Colonic Adenocarcinoma With Minimal Polyposis in a Young Child With Metastatic Hepatoblastoma and Germline APC Mutation

Germline adenomatous polyposis coli (APC) gene mutation is a cancer-predisposing condition commonly presenting as familial adenomatous polyposis. We describe a patient first diagnosed at the age of 3 years with metastatic hepatoblastoma. With a positive family history, germline testing confirmed maternally inherited APC mutation (p.Thr899Ansfs*13). The patient was subsequently diagnosed at 8 years with colonic adenocarcinoma in the absence of macroscopic polyposis. Total colectomy with adjuvant chemotherapy was delivered and the patient remained disease-free for 5 years since the second diagnosis. This report demonstrates the importance of considering germline APC mutation in children with hepatoblastoma, who may benefit from the early institution of colonoscopic surveillance.

Incidence and Outcomes of CNS Tumors in Chinese Children: Comparative Analysis With the Surveillance, Epidemiology, and End Results Program

PURPOSE

Despite being the most common pediatric solid tumors, incidence and outcome of CNS tumors in Chinese children have not been systematically reported. We addressed this knowledge gap by comparing the epidemiology of pediatric CNS tumors in Hong Kong and the United States.

PATIENTS AND METHODS

Data between 1999 and 2016 from a population-based cancer registry in Hong Kong, China, on patients < 18 years old with CNS tumors (Hong Kong cohort) and from the US SEER Program (Asian/Pacific Islander and all ethnicities) were compared. Incidence and overall survival (OS) by histology were evaluated.

RESULTS

During the study period, 526 children were newly diagnosed with CNS tumors in Hong Kong (crude incidence rate, 2.47 per 100,000; 95% CI, 2.26 to 2.69). Adjusted incidences were significantly lower in the Hong Kong (2.51; 95% CI, 2.30 to 2.74) than in the SEER (Asian/Pacific Islander: 3.26; 95% CI, 2.97 to 3.57; P < .001; all ethnicities: 4.10 per 100,000; 95% CI, 3.99 to 4.22; P < .001) cohorts. Incidences of germ cell tumors (0.57 v 0.24; P < .001) were significantly higher, but those of glial and neuronal tumors (0.94 v 2.61; P < .001), ependymomas (0.18 v 0.31; P = .005), and choroid plexus tumors (0.08 v 0.16; P = .045) were significantly lower in Hong Kong compared with SEER (all ethnicities) cohorts. Compared with the SEER (Asian/Pacific Islander) cohort, histology-specific incidences were similar except for a lower incidence of glial and neuronal tumors in Hong Kong (0.94 v 1.74; P < .001). Among cohorts, OS differed only for patients with glial and neuronal tumors (5-year OS: Hong Kong, 52.5%; SEER [Asian/Pacific Islander], 73.6%; SEER [all ethnicities], 79.9%; P < .001).

CONCLUSION

We identified important ethnic differences in the epidemiology of CNS tumors in Chinese children. These results will inform the development of pediatric neuro-oncology services in China and aid further etiologic studies.

LGG-17. CLINICAL OUTCOME OF PEDIATRIC LOW GRADE GLIOMA WITH POSITIVE BRAF-FUSION TREATED WITH MEK INHIBITOR

Background

Low grade glioma (LGG) is the most common central nervous system (CNS) tumor in children. Some are treated with surgery alone, while chemotherapy is given for unresectable tumor with clinical symptoms or progression. Conventional chemotherapy is effective but 30–40% patients may have reactivation of disease requiring re-treatment throughout lifetime. MEK inhibitor for BRAF-fusion positive LGG is a new treatment option for refractory cases.

Methods

Retrospective search in territory-wide pediatric oncology registry for children diagnosed with LGG from 2010–2020 in Hong Kong. To identify patients with molecular confirmed BRAF-fusion positive LGG and any treatment with MEK inhibitor.

Results

Twelve patients (N=12) were identified with BRAF-fusion positive LGG, male:female was 1:2, age 0.3–15.1yr (median 5.0yr) at presentation. The median follow up duration was 1.8yr. Five patients (42%) had surgical resection only. Seven patients (58%) were given chemotherapy with Carboplatin / Vincristine. Five out of seven (n=7) treated patients (71%) have partial response at their initial treatment. Two patients (29%) had progressive disease during treatment and switched to second-line chemotherapy, vinblastine however without improvement. Three patients required re-treatment as disease reactivation. Total five patients had refractory diseases were treated with MEK inhibitor, Trametinib including one diagnosed NF-1. All of them have adverse skin reaction and raised transaminase with one required dose reduction. They have been taking the MEK inhibitor for 0.1–3.3 yr with sustainable partial response.

Conclusion

Pediatric LGG has overall favourable prognosis. Some of them treated with surgery alone while conventional chemotherapy could also achieve satisfactory disease control. For refractory disease with BRAF-fusion positive, MEK inhibitor is a well tolerated treatment option showing sustainable partial response. However, prolonged medication and disturbing skin reaction are still a major concern for this group of patients. On-going clinical trials to compare conventional chemotherapy versus MEK inhibitor could give us more insight about the clinical benefit, patient selection and treatment duration.

Clinical Outcomes and Patient-Matched Molecular Composition of Relapsed Medulloblastoma

We sought to investigate clinical outcomes of relapsed medulloblastoma and to compare molecular features between patient-matched diagnostic and relapsed tumors.

Clinical Outcomes and Complications of Pituitary Blastoma

CONTEXT

Pituitary blastoma is a rare, dysontogenetic hypophyseal tumor of infancy first described in 2008, strongly suggestive of DICER1 syndrome.

OBJECTIVE

This work aims to describe genetic alterations, clinical courses, outcomes, and complications in all known pituitary blastoma cases.

DESIGN AND SETTING

A multi-institutional case series is presented from tertiary pediatric oncology centers.

PATIENTS

Patients included children with pituitary blastoma.

INTERVENTIONS

Genetic testing, surgery, oncologic therapy, endocrine support are reported.

OUTCOME MEASURES

Outcome measures included survival, long-term morbidities, and germline and tumor DICER1 genotypes.

RESULTS

Seventeen pituitary blastoma cases were studied (10 girls and 7 boys); median age at diagnosis was 11 months (range, 2-24 months). Cushing syndrome was the most frequent presentation (n = 10). Cushingoid stigmata were absent in 7 children (2 with increased adrenocorticotropin [ACTH]; 5 with normal/unmeasured ACTH). Ophthalmoplegia and increased intracranial pressure were also observed. Surgical procedures included gross/near-total resection (n = 7), subtotal resection (n = 9), and biopsy (n = 1). Six children received adjuvant therapy. At a median follow-up of 6.7 years, 9 patients were alive; 8 patients died of the following causes: early medical/surgical complications (n = 3), sepsis (n = 1), catheter-related complication (n = 1), aneurysmal bleeding (n = 1), second brain tumor (n = 1), and progression (n = 1). Surgery was the only intervention for 5 of 9 survivors. Extent of resection, but neither Ki67 labeling index nor adjuvant therapy, was significantly associated with survival. Chronic complications included neuroendocrine (n = 8), visual (n = 4), and neurodevelopmental (n = 3) deficits. Sixteen pituitary blastomas were attributed to DICER1 abnormalities.

CONCLUSIONS

Pituitary blastoma is a locally destructive tumor associated with high mortality. Surgical resection alone provides long-term disease control for some patients. Quality survival is possible with long-term neuroendocrine management.

Outcome and molecular analysis of young children with choroid plexus carcinoma treated with non-myeloablative therapy: results from the SJYC07 trial

Background

Choroid plexus carcinoma (CPC) is a rare and aggressive tumor of infancy without a clear treatment strategy. This study describes the outcomes of children with CPC treated on the multi-institutional phase 2 SJYC07 trial and reports on the significance of clinical and molecular characteristics.

Methods

Eligible children <3 years-old with CPC were postoperatively stratified to intermediate-risk (IR) stratum if disease was localized or high-risk (HR) stratum, if metastatic. All received high-dose methotrexate-containing induction chemotherapy. IR-stratum patients received focal irradiation as consolidation whereas HR-stratum patients received additional chemotherapy. Consolidation was followed by oral antiangiogenic maintenance regimen. Survival rates and potential prognostic factors were analyzed.

Results

Thirteen patients (median age: 1.41 years, range: 0.21-2.93) were enrolled; 5 IR, 8 HR. Gross-total resection or near-total resection was achieved in ten patients and subtotal resection in 3. Seven patients had TP53-mutant tumors, including 4 who were germline carriers. Five patients experienced progression and died of disease; 8 (including 5 HR) are alive without progression. The 5-year progression-free survival (PFS) and overall survival rates were 61.5 ± 13.5% and 68.4 ± 13.1%. Patients with TP53-wild-type tumors had a 5-year PFS of 100% as compared to 28.6 ± 17.1% for TP53-mutant tumors (P = .012). Extent of resection, metastatic status, and use of radiation therapy were not significantly associated with survival.

Conclusions

Non-myeloablative high-dose methotrexate-containing therapy with maximal surgical resection resulted in long-term PFS in more than half of patients with CPC. TP53-mutational status was the only significant prognostic variable and should form the basis of risk-stratification in future trials.

ETMR-21. META-ANALYSIS OF PINEAL REGION TUMOURS DEMONSTRATES MOLECULAR SUBGROUPS WITH DISTINCT CLINICO-PATHOLOGICAL FEATURES: A CONSENSUS STUDY

Pineoblastomas (PB) are rare, aggressive pineal gland tumours with poor global OS of 50–70% and only 15–49% OS for patients <4 years, despite intensive treatments. Recently, three independent groups (German Cancer Research Centre, Rare Brain Tumour Consortium/SickKids, St. Jude Children’s Research Hospital) collectively analyzed large tumour cohorts and revealed molecular sub-groups of PB. To harmonize and better characterize clinico-pathologic associations of these sub-groups, we undertook a meta-analysis of molecular and clinical data of the combined cohorts. Unsupervised consensus cluster analyses of global methylation data from 227 unique cases identified five robust molecular sub-groups of pineal region tumours: PB_miRNA_1, PB_miRNA_2, PB_MYC/FOXR2, and PB_RB, mainly comprised of pediatric WHO grade 4 PBs and PNETs; and a fifth group: named PPTID, comprised of mainly pineal parenchymal tumours of intermediate differentiation, a WHO grade 2–3 tumour common in adults. PB_miRNA_1 and PB_miRNA_2 tumours, primarily arising in children (median ages 7.7, 11.4y, respectively), were characterized by alterations of miRNA biogenesis genes DICER1, DROSHA, and DGCR8. PB_MYC/FOXR2 and PB_RB groups, arising in infants/toddlers (median ages 1.4, 2.0y, respectively), were distinguished by recurrent MYC gain/amplification and RB1 loss, respectively. The PPTID group affected mainly adults (median age 33y) and exhibited limited CNAs. Higher rates of metastasis were observed with PB_miRNA_1 (42%), PB_MYC/FOXR2 (38%), and PB_RB (75%) tumours, compared to PB_miRNA_2 (20%) and PPTID (25%). Results from ongoing integrative survival analyses of this large cohort will provide critical data for design of future clinical trials.

ETMR-06. DISSECTING THE MOLECULAR AND DEVELOPMENTAL BASIS OF PINEOBLASTOMA THROUGH GENOMICS

Pineoblastoma (PB) is an aggressive embryonal brain tumor comprising 1% of pediatric CNS tumors. The clinico-molecular heterogeneity and developmental origins underlying PB are poorly understood; therefore, we have assembled a molecular cohort of histologically defined PBs (n=43) with corresponding outcome data. Methylation profiling revealed four molecularly and clinically distinct PB subgroups, including two novel entities. Mutational and transcriptional analysis identified characteristic molecular features of each subgroup, such as mutations in the miRNA processing pathway or FOXR2 proto-oncogene overexpression. Furthermore, subgroups exhibited differences in propensity for metastasis, cytogenetics, and clinical outcomes. To dissect PB developmental origins and resolve PB subgroup biology, we have employed a combination of single-cell genomics and genetically engineered mouse modeling. We created a single-cell transcriptional atlas of the developing murine pineal gland across 11 timepoints and are currently integrating these data with single nuclei RNA-seq data of human PB (n=25). Single-cell analysis of the developing pineal gland revealed three distinct populations of pinealocytes, referred to as early, mid and late pinealocytes, which segregate by developmental stage yet lie along a single developmental trajectory. Preliminary results implicate significant associations between PBs and the early pinealocyte population as well as subgroup-specific differences in intratumoral heterogeneity. Furthermore, this knowledge has informed the downstream generation of biologically faithful disease models, including a transgenic mouse model of the PB-RB subgroup. Remarkably, this model shows up-regulation of key markers of PB such as Crx, Asmt and Otx2 and substantiates early pinealocytes as the probable cell-of-origin for this PB subgroup.

Hepatitis B Virus Seropositivity Is a Poor Prognostic Factor of Pediatric Hepatocellular Carcinoma: a Population-Based Study in Hong Kong and Singapore

Background

Hepatocellular carcinoma (HCC) is a rare hepatic malignancy in children. Hepatitis B virus (HBV) infection is a key predisposing factor in endemic regions but its impact on outcome has not been studied. We aim to evaluate the prognostic implication of HBV seropositivity and role of cancer surveillance in children with HCC from East Asian populations with national HBV vaccination.

Methods

Review of population-based databases for patients (< 18 years old) diagnosed with HCC from 1993 to 2017 in two Southeast Asian regions with universal HBV vaccination (instituted since 1988 and 1987 in Hong Kong and Singapore, respectively).

Results

Thirty-nine patients were identified (Hong Kong, 28; Singapore, 11). Thirty were male; median age at diagnosis was 10.8 years (range, 0.98-16.6). Abdominal pain was the commonest presentation while five patients were diagnosed through surveillance for underlying condition. Alpha-fetoprotein was raised in 36 patients (mean, 500,598 ng/ml). Nineteen had bilobar involvement, among the patients in whom pretreatment extent of disease (PRETEXT) staging could retrospectively be assigned, 3 had stage I, 13 had stage II, 4 had stage III, and 11 had stage IV disease. Seventeen had distant metastasis. HBsAg was positive in 19 of 38 patients. Two patients had fibrolamellar HCC. Upfront management involved tumor resection in 16 (liver transplantation, 2), systemic chemotherapy in 21, interventional procedures in 6 [transarterial chemoembolization (TACE), 5, radiofrequency ablation (RFA), 1], and radiotherapy in 4 (selective internal radiation, 3, external beam radiation, 1). Five-year event-free survival (EFS) and overall survival (OS) were 15.4 ± 6.0 and 26.1 ± 7.2%, respectively. Patient's HBsAg positivity, metastatic disease and inability to undergo definitive resection represent poor prognostic factors in univariate and multivariable analyses. Patients diagnosed by surveillance had significantly better outcome.

Conclusion

Pediatric HCC has poor outcome. HBV status remains relevant in the era of universal HBV vaccination. HBV carrier has inferior outcome and use of surveillance may mitigate disease course.

Correction to: Risk-adapted therapy and biological heterogeneity in pineoblastoma: integrated clinico-pathological analysis from the prospective, multi-center SJMB03 and SJYC07 trials

The original version of this article unfortunately contained a typesetting error in Fig 3c. The corrected Fig. 3 is given in the following page.

Risk-adapted therapy and biological heterogeneity in pineoblastoma: integrated clinico-pathological analysis from the prospective, multi-center SJMB03 and SJYC07 trials

Pineoblastoma is a rare embryonal tumor of childhood that is conventionally treated with high-dose craniospinal irradiation (CSI). Multi-dimensional molecular evaluation of pineoblastoma and associated intertumoral heterogeneity is lacking. Herein, we report outcomes and molecular features of children with pineoblastoma from two multi-center, risk-adapted trials (SJMB03 for patients ≥ 3 years; SJYC07 for patients < 3 years) complemented by a non-protocol institutional cohort. The clinical cohort consisted of 58 patients with histologically diagnosed pineoblastoma (SJMB03 = 30, SJYC07 = 12, non-protocol = 16, including 12 managed with SJMB03-like therapy). The SJMB03 protocol comprised risk-adapted CSI (average-risk = 23.4 Gy, high-risk = 36 Gy) with radiation boost to the primary site and adjuvant chemotherapy. The SJYC07 protocol consisted of induction chemotherapy, consolidation with focal radiation (intermediate-risk) or chemotherapy (high-risk), and metronomic maintenance therapy. The molecular cohort comprised 43 pineal parenchymal tumors profiled by DNA methylation array (n = 43), whole-exome sequencing (n = 26), and RNA-sequencing (n = 16). Respective 5-year progression-free survival rates for patients with average-risk or high-risk disease on SJMB03 or SJMB03-like therapy were 100% and 56.5 ± 10.3% (P = 0.007); respective 2-year progression-free survival rates for those with intermediate-risk or high-risk disease on SJYC07 were 14.3 ± 13.2% and 0% (P = 0.375). Of patients with average-risk disease treated with SJMB03/SJMB03-like therapy, 17/18 survived without progression. DNA-methylation analysis revealed four clinically relevant pineoblastoma subgroups: PB-A, PB-B, PB-B-like, and PB-FOXR2. Pineoblastoma subgroups differed in age at diagnosis, propensity for metastasis, cytogenetics, and clinical outcomes. Alterations in the miRNA-processing pathway genes DICER1, DROSHA, and DGCR8 were recurrent and mutually exclusive in PB-B and PB-B-like subgroups; PB-FOXR2 samples universally overexpressed the FOXR2 proto-oncogene. Our findings suggest superior outcome amongst older children with average-risk pineoblastoma treated with reduced-dose CSI. The identification of biologically and clinically distinct pineoblastoma subgroups warrants consideration of future molecularly-driven treatment protocols for this rare pediatric brain tumor entity.

Medulloblastoma genomics in the modern molecular era

Medulloblastoma (MB) represents a spectrum of biologically and clinically distinct entities. Initially described histopathologically as a small, round blue cell tumor arising in the cerebellum, MB has emerged as a paradigm for molecular classification in cancer. Recent advances in genomic, transcriptomic and epigenomic profiling of MB have further refined molecular classification and complemented conventional histopathological diagnosis. Herein, we review the main clinical and molecular features of the four consensus subgroups of MB (WNT, SHH, Group 3 and Group 4). We also highlight hereditary predisposition syndromes associated with increased risk of MB. Finally, we explore advances in the classification of the consensus molecular groups while also presenting cutting-edge frontiers in identifying intratumoral heterogeneity and cellular origins of MB.

PATH-54. MULTI-DIMENSIONAL MOLECULAR CHARACTERIZATION OF PATIENT-MATCHED MEDULLOBLASTOMA AT DIAGNOSIS AND RELAPSE

INTRODUCTION

Recurrent medulloblastoma (MB) confers an abysmal prognosis with ~10% 5-year overall survival. Optimal treatment paradigms for relapsed disease are largely unknown. Conservation of molecular subgroup at relapse has been described and divergent clonal evolution implicated, yet multi-dimensional molecular characterization of larger cohorts are warranted to substantiate these findings and to disclose potential mechanisms underlying treatment failure and disease recurrence.

METHODS

A multi-institutional series of 85 patient-matched, primary MBs and their relapses was profiled by DNA methylation array (Illumina 450K/850K). Entity and molecular subgroup classifications were assigned using random forest tumor classifiers (Molecular Neuropathology v.11b4). Genome-wide copy-number aberrations were also inferred from these data while parallel next-generation (whole-exome or targeted panel) sequencing on the majority of the cohort facilitated inference of somatic driver mutations.

RESULTS

Comprised of WNT (1%), SHH (41%), Group 3 (22%), Group 4 (35%), primary tumors largely retained subgroup affiliation at relapse with the notable exception of 14% of cases. The majority (8/12) of discrepant classifications were determined to be secondary glioblastomas, while three Group 4 primary tumors relapsed as Group 3. Amongst conserved pairs, copy-number analyses suggest somatic clonal divergence between primary MBs and their respective relapses with an average of 0.8 (range 0–5) primary-specific and 2.0 (range 0–11) relapse-specific cytogenetic alterations. Despite high global methylation correlations between primary/relapse pairs (median 0.95), epigenetic evolution at relapse is suggested by the lower degree of conservation amongst promoter-associated probes (median 0.83, p < 2.2e-16).

CONCLUSION

Secondary malignancy, particularly glioblastoma, may masquerade as relapsed MB, highlighting the utility of molecular characterization for relapsed disease and necessity for vigilant clinical surveillance. By deciphering the evolution of MB from diagnosis to relapse, a fundamental understanding of disease pathogenesis may be garnered, motivating rational and targeted clinical interventions in early therapy and at the time of relapse.

PATH-18. CSF-DERIVED CIRCULATING TUMOR DNA REFLECTS DISEASE COURSE AND CLONAL EVOLUTION IN MEDULLOBLASTOMA

Medulloblastoma (MB) is the most common malignant brain tumor in young children. A multi-modal approach comprises standard of care, and recent advances in molecular studies have identified clinically relevant subgroups. Nonetheless, 30% of MB patients relapse or progress, conferring dismal prognosis. Such suboptimal outcome is partly due to a lack of sensitive biomarkers for response-adapted personalization of treatment and relapse prediction. Circulating tumor DNA has been shown to correlate with disease status in a variety of adult cancers, but studies in pediatric brain tumors, including medulloblastoma, are scarce. Here, we aim to evaluate the utility of profiling cell-free DNA (cfDNA) derived from longitudinally-banked cerebrospinal fluid (CSF) samples collected from children with MB enrolled in two prospective, multi-center trials (SJMB03 and SJMB12, estimated sample size of 100 patients, including 50 with subsequent progression). cfDNA was extracted, quantified, and analyzed for size distribution from pre-centrifuged CSF serially banked during the course of treatment and follow-up. Low-pass whole genome sequencing (LP-WGS) enabled detection of chromosomal and focal copy number alterations (CNAs). CNAs detected in cfDNA were compared against known somatic changes in corresponding primary tumors. Detectability of tumor-specific CNAs in cfDNA was then correlated with tumor burden and patient outcome. Pilot analysis showed presence of arm level and/or focal CNAs in cfDNA from 80% of CSF samples in 20 children with metastatic MB, and longitudinal assessment revealed correlation with clinical course throughout treatment with radiotherapy and chemotherapy. Further comparison of tumor and longitudinal cfDNA derived CNAs revealed divergent genomic alterations implicating potential oncogenic mechanisms underlying treatment failure and recurrence. Our study performed on a large prospective series of MB trial patients substantiates the utility of CSF derived cfDNA as an actionable biomarker in high-risk MB patients while also facilitating understanding of tumor evolution and heterogeneity.

Evaluating pediatric spinal low-grade gliomas: a 30-year retrospective analysis

PURPOSE

Most pediatric spinal tumors are low-grade gliomas (LGGs). Characterization of these tumors has been difficult given their heterogeneity and rare incidence. The objective was to characterize such tumors diagnosed at our institution.

METHODS

Spinal tumors diagnosed in our pediatric patients between 1984 and 2014 were reviewed retrospectively. Demographics, presentation, pathology, imaging, management, and sequelae were examined.

RESULTS

Forty patients had spinal LGG tumors, 24 (62%) of which were pilocytic astrocytomas. The most common initial presentations were pain (n = 15), partial extremity paralysis (n = 13), and ataxia (n = 11), with the diagnosis frequently delayed by months (median = 5.9 months, range 4 days-6.2 years). Twenty-nine patients had some tumor resection, and 8 required adjuvant therapy with chemotherapy (n = 4) or radiation (n = 4) post-resection. Ten other patients received only biopsy for histologic diagnosis, who were treated with chemotherapy (n = 4) or radiation (n = 5) post biopsy. Tumor progression was noted in 16 patients (2 after gross-total resection; 10, partial resection; and 4, biopsy). During the evaluation period, 3 patients died secondary to tumor progression. BRAF status could have shortened progression-free survival: patients with BRAFV600E mutations (n = 3) all experienced progression within 10 months. Long-term sequelae of the disease/treatment were mostly residual neurologic deficits (paresthesia, paralysis), chemotherapy-induced hearing loss, and scoliosis.

CONCLUSIONS

Spinal LGG is a rare entity with significant long-term effects. Although surgery is the most common initial treatment option, more in-depth analysis of molecular biomarkers may improve stratification and prognostication.

Treatment burden and long-term health deficits of patients with low-grade gliomas or glioneuronal tumors diagnosed during the first year of life

BACKGROUND

Low-grade gliomas (LGGs) and low-grade glioneuronal tumors (LGGNTs) diagnosed during the first year of life carry unique clinical characteristics and challenges in management. However, data on the treatment burden, outcomes, and morbidities are lacking.

METHODS

A retrospective study of LGGs and LGGNTs diagnosed in patients younger than 12 months at St. Jude Children's Research Hospital (1986-2015) was conducted.

RESULTS

For the 51 patients (including 31 males), the mean age at diagnosis was 6.47 months (range, 0.17-11.76 months), and the mean follow-up period was 11.8 years (range, 0.21-29.19 years). Tumor locations were hypothalamic/optic pathway (61%), hemispheric (12%), brainstem (12%), cerebellar (8%), and spinal (8%). There were 41 patients with histological diagnoses: 28 had World Health Organization grade 1 tumors, 6 had grade 2 tumors, and 7 had an LGG/LGGNT not definitively graded. Forty-one patients required an active intervention at diagnosis. Throughout their treatment course, 41 patients eventually underwent tumor-directed surgeries (median, 2 surgeries; range, 1-6), 39 received chemotherapy (median, 2 regimens; range, 1-13), and 21 received radiotherapy. Forty patients experienced disease progression (median, 2 progressions; range, 1-18). Ten patients died of progression (n = 5), malignant transformation (n = 2), a second cancer (n = 2), or a shunt infection (n = 1). The 10-year overall survival, progression-free survival, and radiation-free survival rates were 85% ± 5.3%, 16.9% ± 5.3%, and 51.2% ± 7.5%, respectively. Forty-nine patients experienced health deficits (eg, endocrinopathies, obesity, seizures, visual/hearing impairments, neurocognitive impairments, and cerebrovascular disease). Predictors of progression and toxicities were defined.

CONCLUSIONS

Infantile LGG/LGGNT is a chronic, progressive disease universally associated with long-term morbidities and requires multidisciplinary intervention.

Left and Right Ventricular Systolic and Diastolic Functional Reserves Are Impaired in Anthracycline-Treated Long-Term Survivors of Childhood Cancers

BACKGROUND

The aim of this study was to test the hypothesis that left ventricular (LV) and right ventricular (RV) functional reserves are altered in anthracycline-treated long-term survivors of childhood cancers.

METHODS

One hundred three survivors (55% men) aged 25.0 ± 5.8 years at 15.2 ± 5.8 years after chemotherapy and 61 healthy control subjects (52% men) were studied. Tissue Doppler-derived mitral and tricuspid systolic (s) and early diastolic (e) velocities and LV myocardial acceleration during isovolumic contraction (IVA) were determined at rest and during bicycle exercise. The slope of the LV force-frequency relationship was derived from changes in IVA with heart rate during exercise (ΔIVA/Δ[heart rate]). LV and RV functional reserves were further assessed by the systolic functional reserve index (Δs × [1 - 1/s at baseline]) and diastolic functional reserve index (Δe × [1 - 1/e at baseline]).

RESULTS

At baseline, mitral annular tissue Doppler indices were similar between survivors and control subjects (P > .05 for all), while tricuspid s and e velocities were significantly lower in survivors (P < .05 for both). The force-frequency relationship slope (P < .001), LV systolic functional reserve index (P < .001), and RV systolic functional reserve index (P = .001) were significantly lower in survivors than control subjects. For diastolic functional reserve, LV but not RV diastolic functional reserve index was significantly lower in survivors (P < .001). Multivariate analysis revealed survivor status (β = -0.39, P < .001) and baseline LV IVA (β = 0.15, P < .044) as significant determinants of the LV force-frequency relationship.

CONCLUSIONS

LV and RV functional reserves during exercise are impaired in anthracycline-treated long-term survivors of childhood cancer.

Treatment outcome and pattern of failure in hepatoblastoma treated with a consensus protocol in Hong Kong

BACKGROUND AND AIM

We reviewed the results and pattern of failure of the consensus HB/HCC 1996 treatment protocol for pediatric hepatoblastoma (HB) in Hong Kong. The role of SIOPEL and Children's Hepatic tumors International Collaboration (CHIC) risk stratification was evaluated.

METHODS

Patients enrolled on the protocol from 1996 to 2014 were included. PRETEXT staging, SIOPEL, and CHIC risk groups were retrospectively assigned.

RESULTS

Sixty patients were enrolled with median age at diagnosis of 1.1 years and median follow-up time of 6.8 years. Alpha-fetoprotein (AFP) was raised (>100 ng/mL) in 58 (97%) patients. Five (8%) had metastases at presentation and 7 (12%) experienced tumor rupture prior to or during treatment. Twenty-nine patients (48%) received a first-line cisplatin, 5-fluorouracil, and vincristine regimen only while 23 (38%) also had alternative chemotherapeutic agents. Hepatic resection could be performed in 48 (80%) patients. Three (5%) patients underwent upfront liver transplantation. Five-year event-free survival and overall survival rates were 69.2% ± 6.1% and 77.6% ± 5.5% respectively. Among the 16 patients with relapse/progression, 9 had intrahepatic failure only, 5 had distant failure only, and 2 had combined local and distant failure. Predictors of inferior outcome included advanced Evans staging, disease involving both lobes, rupture, low AFP, and suboptimal response to first-line chemotherapy. Assigned in 44 patients, PRETEXT staging, SIOPEL, and CHIC risk groups significantly predicted EFS and OS.

CONCLUSIONS

Although the consensus HB/HCC 1996 protocol led to cure in three-quarters of pediatric HB patients, an upfront risk stratification system is required to identify and improve the outcome of high-risk patients.

Identifying the genetic causes for prenatally diagnosed structural congenital anomalies (SCAs) by whole-exome sequencing (WES)

BACKGROUND

Whole-exome sequencing (WES) has become an invaluable tool for genetic diagnosis in paediatrics. However, it has not been widely adopted in the prenatal setting. This study evaluated the use of WES in prenatal genetic diagnosis in fetuses with structural congenital anomalies (SCAs) detected on prenatal ultrasound.

METHOD

Thirty-three families with fetal SCAs on prenatal ultrasonography and normal chromosomal microarray results were recruited. Genomic DNA was extracted from various fetal samples including amniotic fluid, chorionic villi, and placental tissue. Parental DNA was extracted from peripheral blood when available. We used WES to sequence the coding regions of parental-fetal trios and to identify the causal variants based on the ultrasonographic features of the fetus.

RESULTS

Pathogenic mutations were identified in three families (n = 3/33, 9.1%), including mutations in DNAH11, RAF1 and CHD7, which were associated with primary ciliary dyskinesia, Noonan syndrome, and CHARGE syndrome, respectively. In addition, variants of unknown significance (VUSs) were detected in six families (18.2%), in which genetic changes only partly explained prenatal features.

CONCLUSION

WES identified pathogenic mutations in 9.1% of fetuses with SCAs and normal chromosomal microarray results. Databases for fetal genotype-phenotype correlations and standardized guidelines for variant interpretation in prenatal diagnosis need to be established to facilitate the use of WES for routine testing in prenatal diagnosis.

Tectal glioma as a distinct diagnostic entity: a comprehensive clinical, imaging, histologic and molecular analysis

Tectal glioma (TG) is a rare low-grade tumor occurring predominantly in the pediatric population. There has been no detailed analysis of molecular alterations in TG. Risk factors associated with inferior outcome and long-term sequelae of TG have not been well-documented. We retrospectively studied TGs treated or referred for review at St. Jude Children’s Research Hospital (SJCRH) between 1986 and 2013. Longitudinal clinical data were summarized, imaging and pathology specimen centrally reviewed, and tumor material analyzed with targeted molecular testing and genome-wide DNA methylation profiling. Forty-five patients with TG were included. Twenty-six (57.8%) were male. Median age at diagnosis was 9.9 years (range, 0.01–20.5). Median follow-up was 7.6 years (range, 0.5–17.0). The most common presenting symptoms were related to increased intracranial pressure. Of the 22 patients treated at SJCRH, 19 (86%) required cerebrospinal fluid diversion and seven (32%) underwent tumor-directed surgery. Five patients (23%) received radiation therapy and four (18%) systemic therapy. Ten-year overall and progression-free survival were 83.9 ± 10.4% and 48.7 ± 14.2%, respectively. Long-term morbidities included chronic headaches, visual symptoms and neurocognitive impairment. Lesion ≥3cm², contrast enhancement and cystic changes at presentation were risk factors for progression. Among those with tumor tissue available, 83% showed growth patterns similar to pilocytic astrocytoma and 17% aligned best with diffuse astrocytoma. BRAF duplication (a marker of KIAA1549-BRAF fusion) and BRAF V600E mutation were detected in 25% and 7.7%, respectively. No case had histone H3 K27M mutation. DNA methylation profile of TG was distinct from other brain tumors. In summary, TG is an indolent, chronic disease with unique clinical and molecular profiles and associated with long term morbidities. Large size, contrast enhancement and cystic changes are risk factors for progression.

Selective T cell-depleted haploidentical hematopoietic stem cell transplantation for relapsed/refractory neuroblastoma

Relapsed/refractory NB carries a bleak outcome, warranting novel treatment options. HaploHSCT induces a graft-versus-NB effect via natural killer cell alloreactivity. Review of patients with relapsed/refractory NB who underwent haploHSCT with ex vivo T-cell depletion in our unit from 2013 through 2018. Ten patients were identified (male=5; median age at haploHSCT=6.45 y, range: 3.49-11.02 y). Indications were relapsed in 7 and refractoriness in 3; disease status at haploHSCT was CR in 2, PR in 6, and PD in 2. All patients received peripheral blood stem cell grafts after ex vivo T-cell depletion (CD3/CD19-depletion=1; TCR-αβ/CD19-depletion=4; CD3/CD45RA-depletion=4; and TCR-αβ/CD45RA-depletion=1). Conditioning regimens were fludarabine-based. Neutrophils engrafted on median D + 10 (range: D + 9 to +13), and platelets engrafted (≥20 × 109 /L) on median D + 8 (range: D + 5 to D + 14). Early T- and NK-cell recovery were evident. Of the 10 patients, acute rejection developed in 1 (who died of PD despite rescue HSCT), and 1 died of sepsis before engraftment; 8 experienced full donor-chimerism post-HSCT. Among the 8, 6 experienced CR, 1 died of PD, and 1 died of pulmonary hypertensive crisis before evaluation. At publication, 4 were in remission (2.8, 7.4, 28.5, and 58.9 months). No significant GvHD occurred. HaploHSCT with selective ex vivo T-cell depletion may be a safe and useful salvage strategy for relapsed/refractory NB.

De novo large rare copy-number variations contribute to conotruncal heart disease in Chinese patients

Conotruncal heart anomalies (CTDs) are particularly prevalent congenital heart diseases (CHD) in Hong Kong. We surveyed large (>500 kb), rare (<1% frequency in controls) copy-number variations (CNVs) in Chinese patients with CTDs to identify potentially disease-causing variations. Adults who tested negative for 22q11.2 deletions were recruited from the adult CHD clinic in Hong Kong. Using a stringent calling criteria, high-confidence CNV calls were obtained, and a large control set comprising 3,987 Caucasian and 1,945 Singapore Chinese subjects was used to identify rare CNVs. Ten large rare CNVs were identified, and 3 in 108 individuals were confirmed to harbour de novo CNVs. All three patients were syndromic with a more complex phenotype, and each of these CNVs overlapped regions likely to be important in CHD. One was a 611 kb deletion at 17p13.3, telomeric to the Miller-Dieker syndrome (MDS) critical region, overlapping the NXN gene. Another was a 5 Mb deletion at 13q33.3, within a previously described critical region for CHD. A third CNV, previously unreported, was a large duplication at 2q22.3 overlapping the ZEB2 gene. The commonly reported 1q21.1 recurrent duplication was not observed in this Chinese cohort. We provide detailed phenotypic and genotypic descriptions of large rare genic CNVs that may represent CHD loci in the East Asian population. Larger samples of Chinese origin will be required to determine whether the genome-wide distribution differs from that found in predominantly European CHD cohorts.

Cyclosporin A for persistent or chronic immune thrombocytopenia in children

Twenty percent of children with immune thrombocytopenia (ITP) develop a chronic course where treatment strategy is less established. Cyclosporin A (CSA) has been shown to be effective in small series of children with chronic ITP and might reduce the need for chronic steroid therapy and/or splenectomy. We reviewed consecutive patients below 18 years old with persistent or chronic ITP treated with CSA in our unit between January 1998 and June 2015. Thirty patients (14 boys and 16 girls) were included. The median age at initial diagnosis of ITP was 5 years (range 0.5-16.2 years). CSA was started at a median of 13.9 months (range 3.4-124 months) after initial diagnosis and given for a median duration of 9.3 months (range 0.2-63.9 months). The median platelet count before commencement was 12 × 10(9)/L (range 4-199 × 10(9)/L). The median dose of CSA was 6 mg/kg/day (range 2.4-7.5 mg/kg/day). Complete response (CR) or response (R) was achieved in 17 patients (57 %), and 7 (23 %) had sustained response. Side effects (most commonly hirsutism) were tolerable and reversible. CSA appeared effective in about half of persistent or chronic ITP patients and safe as a second-line agent in managing these children.

Remission With Donor Lymphocyte Infusion in a Child With Marrow Relapse After Haploidentical Stem Cell Transplantation for Relapsed Stage 4 Neuroblastoma

A 7-year-old male with Stage 4 neuroblastoma was treated with chemotherapy and autologous hematopoietic stem cell transplantation (HSCT), resulting in partial response with residual bone and marrow disease. He proceeded to haploidentical-HSCT with his mother as donor and achieved remission. The patient developed marrow relapse 2 years after haploidentical-HSCT with cytopenia and dropping donor chimerism. Donor lymphocyte infusion (DLI) using mother's whole blood was given resulting in clearance of marrow disease, resolution of cytopenia, and full donor chimerism. This is the first report of successful treatment for neuroblastoma relapse after haploidentical-HSCT using DLI alone, supporting the role of adoptive cell therapy post-HSCT in neuroblastoma.

Refractory acute lymphoblastic leukemia in Chinese children: bridging to stem cell transplantation with clofarabine, cyclophosphamide and etoposide

Refractory or relapsed acute lymphoblastic leukemia (r/r ALL) represents the leading cause of cancer mortality in children. Clofarabine is effective in inducing remission thus enabling bridging to hematopoietic stem cell transplantation (HSCT). We report the results in treating Hong Kong Chinese pediatric patients with r/rALL by clofarabine/cyclophosphamide/etoposide (CLO-218) combination therapy. A retrospective review of patients treated between January 2009 and December 2014 in the two tertiary referral pediatric oncology units in Hong Kong. Thirteen patients were identified. All were Chinese and seven were male. Median age at clofarabine treatment was 8 years and the median duration of follow-up was 10 months. Nine patients had B-ALL and four had T-ALL. All were refractory to the preceding regimen(s). The median number of prior treatment regimens was 2; two patients had previous HSCT. Complete remission (CR) was achieved in five patients, Complete remission with incomplete counts (CRi) in two, PR in two, and non-remission (NR) in two. All four patients with T-ALL responded with three patients achieving CR. Eight out of nine patients who responded could be bridged to HSCT. Among those who were transplanted, four remained alive and in remission, three relapsed post-HSCT, and one died from transplant-related mortality. Treatment toxicities were common including febrile neutropenia in all subjects and culture-proven bacteremia in five patients. Hepatotoxicity was mild and reversible with no case of veno-occlusive disease. The clofarabine-based regimen is a promising strategy to induce disease remission in r/rALL and bridge to HSCT. Septic complications are, however, frequent necessitating prompt management with adequate supportive care in specialized centers.

Under-recognition of 22q11.2 deletion in adult Chinese patients with conotruncal anomalies: implications in transitional care

22q11.2 deletion syndrome (22q11.2DS) is a multi-systemic disorder with high phenotypic variability. Under-diagnosis in adults is common and recognition of facial dysmorphic features can be affected by age and ethnicity. This study aims to determine the prevalence of undiagnosed 22q11.2DS in adult Chinese patients with conotruncal anomalies and to delineate their facial dysmorphisms and extra-cardiac manifestations. We recruited consecutively 156 patients with conotruncal anomalies in an adult congenital heart disease (CHD) clinic in Hong Kong and screened for 22q11.2DS using fluorescence-PCR and fluorescence in-situ hybridization. Assessment for dysmorphic features was performed by a cardiologist at initial screening and then by a clinical geneticist upon result disclosure. Clinical photographs were taken and childhood photographs collected. Eighteen patients (11.5%) were diagnosed with 22q11.2DS, translating into 1 previously unrecognized diagnosis of 22q11.2DS in every 10 adult patients with conotruncal anomalies. While dysmorphic features were detected by our clinical geneticist in all patients, only two-thirds were considered dysmorphic by our cardiologist upon first assessment. Evolution of facial dysmorphic features was noted with age. Extra-cardiac manifestations included velopharyngeal incompetence or cleft palate (44%), hypocalcemia (39%), neurodevelopmental anomalies (33%), thrombocytopenia (28%), psychiatric disorders (17%), epilepsy (17%) and hearing loss (17%). We conclude that under-diagnosis of 22q11.2DS in Chinese adults with conotruncal defects is common and facial dysmorphic features may not be reliably recognized in the setting of adult CHD clinic, referral for genetic evaluation and molecular testing for 22q11.2DS should be offered to patients with conotruncal defects.

Expanded Prader-Willi syndrome due to chromosome 15q11.2-14 deletion: report and a review of literature

We report on a male infant with de novo unbalanced t(5;15) translocation resulting in a 17.23 Mb deletion within 15q11.2-q14 and a 25.12 kb deletion in 5pter. The 15q11.2-q14 deletion encompassed the 15q11.2-q13 Prader-Willi syndrome (PWS) critical region and the recently described 15q13.3 microdeletion syndrome region while the 5pter deletion contained no RefSeq genes. From our literature review, patients with similar deletions in chromosome 15q exhibit expanded phenotype of severe developmental delay, protracted feeding problem, absent speech, central visual impairment, congenital malformations and epilepsy in addition to those typical of PWS. The patient reported herein had previously unreported anomalies of mega cisterna magna, horseshoe kidney and the rare neonatal interstitial lung disease known as pulmonary interstitial glycogenosis. Precise breakpoint delineation by microarray is useful in patients with atypical PWS deletions to guide investigation and prognostication.