Evolution of the Innovative Therapies for Children With Cancer Consortium Trial Portfolio for Drug Development for Children With Cancer

PURPOSE

The aim of the Innovative Therapies for Children with Cancer (ITCC) consortium is to improve access to novel therapies for children and adolescents with cancer. The evolution of the ITCC clinical trial portfolio since 2003 was reviewed.

METHODS

All ITCC-labeled phase I/II trials opened between January 1, 2003 and February 3, 2018 were analyzed in two periods (2003-2010 and 2011-2018), and data were extracted from the ITCC database, regulatory agencies' registries, and publications.

RESULTS

Sixty-one trials (62% industry-sponsored) enrolled 3,198 patients. The number of trials in the second period increased by almost 300% (16 v 45). All biomarker-driven trials (n = 14) were conducted in the second period. The use of rolling six and model-based designs increased (1 of 9, 11% v 21 of 31, 68%), and that of 3 + 3 designs decreased (5 of 9, 55% v 5 of 31, 16%; P = .014). The proportion of studies evaluating chemotherapeutics only decreased (5 of 16, 31% v 4 of 45, 9%), the proportion of single-agent targeted therapies did not change (9 of 16, 56.2% v 24 of 45, 53.3%), the proportion of combination targeted therapies trials increased (2 of 16, 12%, v 17 of 45, 38%), the proportion of randomized phase II trials increased (1 of 7, 14% v 8 of 14, 57%). More trials were part of a pediatric investigation plan in the second period (4 of 16, 25% v 21 of 45, 46%). The median time for Ethics Committees' approvals was 1.7 times longer for academic compared with industry-sponsored trials.

CONCLUSION

This study reports a shift in the paradigm of early drug development for childhood cancers, with more biologically relevant targets evaluated in biomarker-driven trials or in combination with other therapies and with more model-based or randomized designs and a greater focus on fulfilling regulatory requirements. Improvement of trial setup and recruitment could increase the number of patients benefiting from novel agents.

Evaluating preclinical evidence for clinical translation in childhood brain tumours: Guidelines from the CONNECT, PNOC, and ITCC brain networks

Clinical outcomes for many childhood brain tumours remain poor, despite our increasing understanding of the underlying disease biology. Advances in molecular diagnostics have refined our ability to classify tumour types and subtypes, and efforts are underway across multiple international paediatric neuro-oncology consortia to take novel biological insights in the worst prognosis entities into innovative clinical trials. Whilst for the first time we are designing such studies on the basis of disease-specific biological data, the levels of preclincial evidence in appropriate model systems on which these trials are initiated is still widely variable. We have considered these issues between CONNECT, PNOC and ITCC-Brain, and developed a framework in which we can assess novel concepts being brought forward for possible clinical translation. Whilst not intended to be proscriptive for every possible circumstance, these criteria provide a basis for self-assessment of evidence by laboratory scientists, and a platform for discussion and rational decision-making prior to moving forward clinically.

MEDB-84. The French experience of ELP1-related medulloblastomas

Medulloblastoma (MB), the most frequent embryonic tumor of the cerebellum is classified into four molecular subgroups (WNT group, SHH group, group 3 and group 4). Although the vast majority of MB are sporadic, predisposing genetic diseases have been described in rare WNT MB and more frequently in the SHH group. In a recent pediatric series of SHH-MB, germline alterations of the ELP1 gene have been described in 14% of cases, making this gene the most frequent genetic predisposition in MB. We have investigated the potential interest of ELP1 immunostaining on a large cohort of 132 MB. A complete loss of ELP1 staining was observed in 12 SHH MB (among 57 total SHH MB: 21%). The loss of ELP1 immunostaining was well correlated with the presence of a bi-allelic alteration of the gene except for one case for which the MB had a loss of ELP1 protein expression demonstrated by immunohistochemistry (IHC) and confirmed by whole proteome analysis, although no obvious genetic alteration in the coding sequence of ELP1 could be found. Molecular analysis of a large “molecular” cohort of 266 MB from French centers for which somatic ELP1 was sequenced allows to identify 12 additional MB with bi-allelic ELP1 genetic alterations. Our results demonstrate the benefit of the ELP1 IHC as an accurate and reliable tool to screen ELP1-deficient MB. This new immunohistochemical tool will now be advantageously used to screen SHH MB upfront for genetic alteration in ELP1, and will subsequently help orientating these patients towards genetic counseling.

PATH-12. A new powerful tool to simultaneously deliver DNA methylation profile and driver fusions detection based on Nanopore Sequencing

The fast advances in molecular biology have led to the discovery of new genetic and epigenetic driver events that play a key role in the pathogenesis of central nervous system (CNS) tumors. These data showed the importance of molecular biology, and in particular methylation profiling and fusion detection, to complete the histological examination. Exploring all these complex genomic and epigenomic alterations with the technologies implemented in the routine diagnosis requires massive laboratory equipment. In addition, it could take weeks before getting data that could be important to adapt the diagnosis, prognosis, and to ultimately guide the treatment’s choice. We describe the innovative potential of a nanopore sequencing device to obtain fast and multiple information to characterize CNS tumors. Adaptive-sampling is a software-controlled enrichment unique method that allows simultaneous methylation profiling, copy number landscape assessment, and fusion gene detection. Thereby, this technology brings comprehensive molecular information that could be very important for CNS tumor classification in a very short delay (below one week) and with a relative low cost compared to the combined other molecular analysis needed to get the same information. We report ten cases of diverse CNS tumors with already known oncogenic structural variants such as YAP1-MAMLD1 fused ependymoma, CNS neuroblastoma with FOXR2 activation, CNS high-grade neuroepithelial tumor with BCOR and MEN1 alteration, and atypical teratoid rhabdoid tumors (ATRT). For these tumors, using adaptive sampling with the nanopore sequencing, we were able to detect fusion genes as driver events, while obtaining at the same time the methylation profile to corroborate the tumor classification. Our results with this combined approach, never described before, demonstrate its feasibility as a new extremely powerful tool and show remarkable perspectives for this technology to bring a fast and comprehensive tumor molecular characterization.

QOL-28. Clinico-molecular correlates of quality of survival and neurocognitive outcomes in medulloblastoma; a meta-analysis of the SIOP-UKCCSG-PNET3 and HIT-SIOP-PNET4 trials

Determinants of survivorship outcomes are emerging from limited studies of medulloblastoma (MB) survivors. We undertook an integrated analysis of biological (tumour group, host genetics) and clinico-demographic features in patients treated on the SIOP-UKCCSG-PNET3 and HIT-SIOP-PNET4 clinical trials with available quality of survival (QoS) data (n=218), to determine key correlates of survivorship, and their clinical potential. Treatment/demographic factors and molecular subgroup (MBWNT, MBSHH, MBGrp3, MBGrp4) were assessed against health status, behavioural functioning, and health-related quality of life (HrQoL). In DNA from HIT-SIOP-PNET4 (n=74), 39 candidate SNPs with known modifying effects on neurocognitive outcomes (e.g., involved in oxidative stress/inflammation) were genotyped and assessed against Wechsler Intelligence Scale (WISC) scores. As expected, MBSHH was associated with improved HrQoL, but subgroup did not associate further with QoS outcomes. SIOP-UKCCSG-PNET3 patients receiving chemotherapy before craniospinal irradiation (CSI) had significantly lower health status (p=0.021) and behavioural functioning (p<0.016) compared to patients treated with CSI alone, and those treated on both arms (maintenance chemotherapy and hyperfractionated (36Gy) or standard (23.4Gy) CSI) of HIT-SIOP-PNET4. SIOP-UKCCSG-PNET3 patients receiving CSI-only had better HrQoL scores than those who received pre-CSI chemotherapy and both HIT-SIOP-PNET4 arms (p=0.004). Females reported worse HrQoL/behavioural functioning across both trials (p<0.04). In HIT-SIOP-PNET4, longer intervals from diagnosis to CSI predicted worse HrQoL/health status (p<0.05). Neither molecular group nor clinico-demographic features tested were associated with neurocognition. In contrast, 6 SNPs significantly associated with ≥1 WISC domain; 4/6 showed multiple associations and were independently prognostic; further associations were apparent at the gene/pathway level. This large, integrated and multi-disciplinary analysis of two independent trials cohorts has revealed multiple factors predictive of medulloblastoma survivorship including treatment (chemotherapy, time to CSI), tumour (molecular group) and host genetic factors. Assessment in further prospective series are required to determine their potential as a basis for modifications to disease management.

ETMR-03. Intra- and extra-cranial BCOR-ITD tumours are separate entities within the BCOR-rearranged family

BCOR-ITD tumours form an emerging family of aggressive entities with an internal tandem duplication (ITD) in the last exon of the BCOR gene. The family includes cerebral tumours, termed central nervous system BCOR-ITD (CNS BCOR-ITD), and sarcomatous types described in the kidney as clear cell sarcoma of the kidney (CCSK), in the endometrium as high-grade endometrial stromal sarcoma (HG-ESS), in bone, and in soft tissue as undifferentiated round cell sarcoma (URCS) or primitive myxoid mesenchymal tumour of infancy (PMMTI). Based on a series of 33 retrospective cases, including 10 CNS BCOR-ITD and 23 BCOR-ITD sarcomas, we interrogated the homogeneity of the entity regarding clinical, radiological and histopathological findings, and molecular signatures. Whole transcriptomic sequencing and DNA methylation profiling were used for unsupervised clustering. Histopathological review revealed marked differences between CNS BCOR-ITD and BCOR-ITD sarcomas. These two groups were consistently segregated by unsupervised clustering of expression (n=22) and DNA methylation (n=21) data. Proximity between the two groups may result from common somatic changes within key pathways directly related to the novel activity of the ITD itself. Conversely, comparison of gene signatures with single-cell RNAseq atlases suggests that the distinction between BCOR-ITD sarcomas and CNS BCOR-ITD may result from differences in cells of origin.

FIREFLY-1 (PNOC 026): A phase 2 study to evaluate the safety and efficacy of tovorafenib (DAY101) in pediatric patients with RAF-altered recurrent or progressive low-grade glioma or advanced solid tumors

TPS10062

Background: RAF gene fusions ( BRAF and RAF1) and BRAF V600E mutations are oncogenic drivers found on a mutually exclusive basis in most pediatric low-grade gliomas (LGGs). In addition, RAF fusions ( BRAF and RAF1) have also been identified in other pediatric solid tumors. Tovorafenib (DAY101) is an investigational, oral, highly selective, CNS-penetrant, small molecule, type II pan-RAF inhibitor. In contrast to type I BRAF inhibitors, tovorafenib does not induce RAS-dependent paradoxical activation of the MAPK pathway. In the phase 1 PNOC014 study in pediatric patients with recurrent/progressive LGG, tovorafenib was well tolerated and 7/8 patients with tumor harboring RAF fusions had meaningful clinical benefit. Recently, a child with a novel SNX8-BRAF fusion spindle cell sarcoma demonstrated a rapid and deep response when treated with tovorafenib. Methods: FIREFLY-1 (NCT04775485) is an open-label, multicenter, phase 2 study evaluating the safety and efficacy of tovorafenib monotherapy in pediatric patients with RAF-altered recurrent or progressive LGG or advanced solid tumors. The initial design included only patients with LGG (arm 1). Two new arms have now been added; arm 2 will allow tovorafenib treatment for patients with LGG harboring an activating RAF alteration after completion of enrollment to arm 1 and prior to tovorafenib regulatory approval; arm 3 will enroll patients with advanced solid tumors harboring an activating RAF fusion. Eligible patients are 6 months to 25 years of age, who have received ≥1 prior line of systemic therapy with documented radiographic progression, have evaluable and/or measurable disease by appropriate criteria, a Karnofsky or Lansky performance score of at least 50, and adequate organ function. Patients are excluded if their tumor has other driver mutations, they have neurofibromatosis type 1, central serous retinopathy, retinal vein occlusion, clinically significant active cardiovascular disease, or are currently being treated with a strong CYP2C8 inhibitor or inducer other than those allowed per protocol. Approximately 140 patients in total will be enrolled including 60 in arm 1, 60 in arm 2 and 20 in arm 3. Tovorafenib will be administered at 420 mg/m2 (not to exceed 600 mg) weekly (days 1, 8, 15 and 22) for 26, 28-day cycles (in the absence of disease progression or unacceptable toxicity). They may then continue tovorafenib or enter a drug holiday period. The primary endpoint is overall response rate, as defined by the RANO criteria (arm 1) or RECIST v1.1 (arm 3) and as determined by an independent radiology review committee. Secondary endpoints (arms 1 and 3) include safety and tolerability, pharmacokinetics, duration of response, time to response and progression-free survival. Tovorafenib is available in tablet or liquid suspension formulations. Clinical trial information: NCT04775485.

Efficacy and safety of larotrectinib in pediatric patients with tropomyosin receptor kinase (TRK) fusion-positive cancer: An expanded dataset

10030

Background: Neurotrophic tyrosine receptor kinase ( NTRK) gene fusions are oncogenic drivers in various tumor types across all ages. Larotrectinib is a first-in-class, central nervous system (CNS)-active, highly selective tropomyosin receptor kinase (TRK) inhibitor approved for pediatric and adult patients (pts) with TRK fusion-positive cancer, demonstrating an objective response rate (ORR) of 88% across 78 pediatric pts with non-CNS cancers (van Tilburg et al, SIOP 2021). We report an analysis of the efficacy and safety of larotrectinib in an expanded dataset of pediatric pts with TRK fusion-positive cancer. Methods: Pediatric pts (< 18 years) with non-CNS TRK fusion-positive cancer in larotrectinib clinical trials (NCT02637687, NCT02576431) were included and ORR (RECIST v1.1) was investigator (INV)-assessed. Data cut-off was July 20, 2021. Results: A total of 94 pts were included in this analysis. Tumor types included infantile fibrosarcoma (52%), other soft tissue sarcoma (40%), congenital mesoblastic nephroma (2%), thyroid cancer (2%), bone sarcoma (1%), breast cancer (1%), and melanoma (1%). Pts had gene fusions involving NTRK1 (43%), NTRK2 (3%), or NTRK3 (54%). Median age was 2.2 years (range 0–18 years). Of the 62 (66%) pts who received prior systemic therapy, 32 (52%) received ≥2 lines. The INV-assessed best ORR for the 93 evaluable pts was 84% (95% confidence interval [CI] 75–91): 35 (38%) complete response (CR; including two pending confirmation and 10 pathological CR), 43 (46%) partial response (two pending confirmation), 11 (12%) stable disease, two (2%) progressive disease, and two (2%) not determined. The median time to response was 1.8 months. Overall, median duration of response was 43.3 months (95% CI 23.4–NE); median follow-up was 26.0 months. Median progression-free survival and overall survival (OS) were 37.4 months (95% CI 22–NE) and not reached, respectively; median follow-up was 21.2 and 30.3 months, respectively. The 36-month OS rate was 93% (95% CI 86–99). Treatment duration ranged from 1+ to 63+ months. At data cut-off, 31 pts had progressed; 18 continued treatment post-progression for ≥4 weeks. There were no treatment-related deaths. Treatment-related adverse events (TRAEs) occurred in 81% of pts (23% were Grade [G] 1, 28% G2, 25% G3, and 5% G4). The most common TRAE was increased aspartate aminotransferase (31 pts [33%]). Four pts (4%) discontinued treatment due to TRAEs. Neurological TRAEs occurred in 12% of pts (5% were G1, 4% G2, and 2% G3). The most common neurological TRAE was headache (5 pts [5%]). Conclusions: In this expanded dataset, larotrectinib continues to demonstrate rapid and durable tumor-agnostic efficacy, extended survival, and a favorable safety profile in pediatric pts with TRK fusion-positive cancer. These results highlight the importance of identifying NTRK gene fusions in pediatric solid tumors. Clinical trial information: NCT02576431, NCT02637687.

Long-term control and safety of larotrectinib in a cohort of adult and pediatric patients with tropomyosin receptor kinase (TRK) fusion primary central nervous system (CNS) tumors

2010

Background: Neurotrophic tyrosine receptor kinase ( NTRK) gene fusions are known oncogenic drivers in a variety of tumor types. Larotrectinib is a highly selective, CNS-active TRK inhibitor that demonstrated an objective response rate (ORR) of 30% and a 24-week disease control rate (DCR) of 73% across 33 evaluable adult and pediatric patients with TRK fusion primary CNS tumors, as of July 2020 (Doz et al, Neuro Oncol 2021). We report updated data on an expanded dataset of patients. Methods: Patients with TRK fusion primary CNS tumors in two clinical trials (NCT02637687, NCT02576431) were included. Larotrectinib was administered at 100 mg twice daily (BID) in adults and 100 mg/m2 (max 100 mg) BID in pediatric patients. Response was investigator-assessed. Results: As of July 2021, 38 adult and pediatric patients with TRK fusion primary CNS tumors were identified: high-grade glioma (HGG; n =23), low-grade glioma (LGG; n =9), and other (n =6; includes glioneuronal, neuroepithelial, diffuse leptomeningeal, neuroblastoma, recurrent small round blue cell, and not otherwise specified). Median age at enrollment was 10.8 years (range 1.3–79.0; 28 [74%] patients < 18 years old). The gene fusions involved NTRK2 (n = 28), NTRK1 (n = 6), and NTRK3 (n = 4). Sixteen (42%) patients received one prior line of systemic therapy and 16 (42%) received ≥2 prior lines. The ORR for 37 evaluable patients was 30% (95% confidence interval [CI] 16–47): three complete responses, eight partial responses, 21 stable disease (16 patients ≥24 weeks), and five progressive disease. The 24-week DCR was 73% (95% CI 56–86) for all patients, 68% (95% CI 45–86) for patients with HGG, and 89% (95% CI 52–100) for patients with LGG. Twenty-five of 31 patients (81%) with measurable disease at baseline had tumor shrinkage. Median time to response was 1.9 months. Median duration of response (DoR) was not reached; median follow-up was 25.6 months. The 12-month DoR rate was 64%. Median progression-free survival (PFS) was 16.5 months (95% CI 6.7–not estimable); median follow-up was 27.4 months. Median overall survival (OS) was not reached; median follow-up was 26.7 months. The 24-month OS rate was 65%. Treatment duration ranged from 0.1+ to 38.7+ months. Twenty-two patients (58%) progressed on treatment and three continued treatment post-progression for ≥4 weeks. Treatment-related adverse events (TRAEs) were reported in 21 patients (55%); the majority of these patients (18/21 [86%]) reported Grade 1 or 2 TRAEs. No Grade 3 or higher treatment-related neurological adverse events were reported. There were no treatment discontinuations due to TRAEs. Conclusions: Larotrectinib achieved a high DCR, rapid and durable responses, and a manageable safety profile in patients with TRK fusion primary CNS tumors. These results support testing for NTRK gene fusions in patients with CNS tumors. Clinical trial information: NCT02637687, NCT02576431.

Long-term efficacy and safety of larotrectinib in a pooled analysis of patients with tropomyosin receptor kinase (TRK) fusion cancer

3100

Background: Neurotrophic tyrosine receptor kinase ( NTRK) gene fusions are oncogenic drivers in multiple tumors. Larotrectinib is a highly selective, central nervous system (CNS)-active tropomyosin receptor kinase (TRK) inhibitor, approved to treat adult and pediatric patients (pts) with TRK fusion cancer. In an integrated analysis of 206 pts with non-primary CNS TRK fusion cancer, larotrectinib demonstrated an investigator-assessed objective response rate (ORR) of 75%; median progression-free survival (PFS) was 35.4 months (mo; Hong et al, ASCO 2021). We report updated efficacy and safety data based on central review assessments in an expanded dataset. Methods: Data were pooled from three clinical trials (NCT02576431, NCT02122913, and NCT02637687) of pts with non-primary CNS TRK fusion cancer treated with larotrectinib. Larotrectinib was administered until disease progression, withdrawal, or unacceptable toxicity. ORR was assessed by independent review committee (IRC) per RECIST v1.1. Data cut-off was July 20, 2021. Results: As of data cut-off, 244 of 269 larotrectinib-treated pts were evaluable for efficacy by IRC. There were 25 different tumor types. The most common were soft tissue sarcoma (STS [43%], including infantile fibrosarcoma [18%] and other STS [25%]), thyroid (11%), lung (10%), salivary gland (9%), and colorectal (7% [colon, n = 18; rectal, n = 1]). Ninety-four (35%) pts were aged < 18 years; 175 (65%) were ≥18 years. Pts had gene fusions involving NTRK1 (46%), NTRK2 (3%), or NTRK3 (51%). A total of 27%, 28%, and 45% of pts had 0, 1, and ≥2 prior lines of systemic therapy, respectively. The ORR was 69% (95% confidence interval [CI] 63–75): 64 (26%) complete response (CR), including 13 (5%) pathological CR, 104 (43%) partial response,41 (17%) stable disease, 20 (8%) progressive disease, and 15 (6%) not determined. Median time to response was 1.8 mo (range 0.9–16.2). Median duration of response (DoR) was 32.9 mo (95% CI 27.3–41.7); median follow-up was 28.3 mo. Median PFS was 29.4 mo (95% CI 19.3–34.3); median follow-up was 29.3 mo. At a median follow-up of 32.2 mo, median overall survival (OS) was not reached; the 48-mo OS rate was 64% (95% CI 55–73). Treatment duration ranged from 0.1 to 67.9 months. Treatment-related adverse events (TRAEs) were mainly Grade 1–2; 50 (20%) pts had Grade 3–4 TRAEs. Five (2%) pts discontinued treatment due to TRAEs. To exclude the possible confounding effect of ongoing enrollment on median DoR, we conducted an exploratory analysis in the subset of 164 pts who were analyzed as of July 2019. The ORR was 74% (95% CI 67–81) and median DoR was 34.5 mo (95% CI 27.6–43.3); median follow-up was 34.1 mo. Conclusions: With longer follow-up, larotrectinib continued to demonstrate rapid and durable responses, extended survival benefit, and a favorable safety profile. These results highlight the importance of testing for NTRK gene fusions in cancer pts. Clinical trial information: NCT02576431, NCT02122913, NCT02637687.

Updated health-related quality of life of patients with TRK-fusion cancer treated with larotrectinib in clinical trials

6563

Background: NTRK gene fusions have been identified as oncogenic drivers in patients (pts) with TRK fusion cancer across multiple solid tumors. Larotrectinib, a highly selective, CNS-active TRK inhibitor has shown high response rates, durable disease control, and a favorable safety profile in pts with TRK fusion cancer and is approved in over 40 countries. Larotrectinib has demonstrated rapid health-related quality of life (HRQOL) improvement in a group of 57 adult and pediatric pts (Kummar et al, Curr Prob Canc 2021). Here, we report updated HRQOL results for larger group of pts treated with larotrectinib. Methods: HRQOL data were collected in two ongoing trials (NCT02576431, NCT02637687) of larotrectinib in pts with TRK-fusion cancer using the EORTC QLQ-C30, EQ-5D-5L questionnaires and were analyzed descriptively and longitudinally. Scores from the EORTC QLQ-C30 Global Health Status (GHS), EQ-5D-5L VAS range from 0 to 100, with higher scores indicating better QOL. We also calculated the proportion of pts with either below normal or normal and above normal HRQOL scores against values in the literature for the US general population. Results: By July 2021, 113 adults with TRK-fusion cancer had received larotrectinib and completed the baseline (BL) and ≥ 1 post-BL questionnaire. The majority of pts had clinically meaningful HRQOL improvements during treatment (Table). For EORTC QLQ-C30 GHS, most adults maintained or improved scores from BL at or above the normal population level category. HRQOL improvements (change from BL > 0) occurred after ̃2 months of treatment in 75% of adults. Median duration of pts with sustained improvement in EORTC QLQ-C30 GHS, and EQ-5D-5L VASs was 12.5 months (range, 1.8-34.1), and 12.9 months (range, 1.8-34.0), respectively. HRQOL results were consistent across multiple data cuts. Conclusions: Patients with TRK-fusion cancer treated with larotrectinib continued to have rapid, clinically meaningful, and sustained improvements in HRQOL. Clinical trial information: NCT02576431, NCT02122913, NCT02637687.

Clinical characteristics and outcome of a large cohort of patients with primary central nervous system (CNS) tumors and tropomyosin receptor kinase (TRK) fusion

2052

Background: TRK fusions are detected in less than 3% of central nervous system (CNS) tumors. Given their rarity, there are limited data on the clinical course of affected patients. Methods: We contacted 166 oncology centers worldwide to retrieve data on patients with TRK fusion-driven CNS tumors. Data extracted included demographics, histopathology, TRK gene fusion, treatment modalities and outcomes. Results: Ninety-two patients with TRK fusion-driven primary CNS tumors were identified including 76 pediatric patients (82.6%), 15 adults (16.3%) and 1 not specified (1.1%). Median age at diagnosis was 4.4 years (range 0.0–78.3) and 58.7 % were male. NTRK2 gene fusions were found in 45 patients (48.9%), NTRK1 and NTRK3 aberrations were detected in 27 (29.3%) and 20 (21.7%), respectively. Tumor types included 56 high-grade gliomas (HGG; 60.9%), 20 low-grade gliomas (LGG; 21.7%), 4 embryonal tumors (4.3%) and 12 others (13.0%). Median follow-up was 40.5 months (range 3–226). During the course of their disease, 75 (81.5%) patients underwent surgery with a treatment intent, 67 (72.8%) patients received chemotherapy, 50 (54.3%) patients received radiation therapy, while 47 (51.1%) patients received NTRK inhibitors (6 as first line treatment). There were significant differences in the median progression-free (PFS) and overall survival (OS) between pediatric patients compared to adults. The pediatric median PFS was 32 months (95% CI: 15.5–48.5) compared to 8 months for the adult (95% CI: 4.5–11.5, p = 0.015). The pediatric median OS was 182 months (95% CI: 25.1–338.9) compared to 24 months (95% CI: 18.3–29.7 p < 0.001) for adult patients. There was no difference in the PFS of LGG compared to HGG. However, the OS was significantly worse for the HGG when compared to LGG (p = 0.039). The median OS for LGG was not reached and the median OS for HGG was 70 months (95% CI 7.5–132.5). Nineteen patients with HGG (38.0 % 19/50 evaluable patients) died compared to only one patient with LGG (5.6% 1/18 evaluable patients, p = 0.014). Conclusions: We report the largest cohort of patients with TRK fusion-driven primary CNS tumors. These results will help us to better understand clinical evolution and compare outcomes with ongoing clinical trials.

Imaging Features with Histopathologic Correlation of CNS High-Grade Neuroepithelial Tumors with a BCOR Internal Tandem Duplication

BACKGROUND AND PURPOSE

A new brain tumor entity occurring in early childhood characterized by a somatic BCL6 corepressor gene internal tandem duplication was recently described. The aim of this study was to describe the radiologic pattern of these tumors and correlate this pattern with histopathologic findings.

MATERIALS AND METHODS

This retrospective, noninterventional study included 10 children diagnosed with a CNS tumor, either by ribonucleic acid-sequencing analysis or deoxyribonucleic acid methylation analysis. Clinical, radiologic, and histopathologic data were collected. A neuropathologist reviewed 9 tumor samples. Preoperative images were analyzed in consensus by 7 pediatric radiologists.

RESULTS

All tumors were relatively large (range, 4.7-9.2 cm) intra-axial peripheral masses with well-defined borders and no peritumoral edema. All tumors showed mild and heterogeneous enhancement and marked restriction on DWI of the solid portions. Perfusion imaging showed a relatively lower CBF in the tumor than in the adjacent normal parenchyma. Nine of 10 tumors showed areas of necrosis, with the presence of hemorrhage in 8/10 and calcifications in 4/7. Large intratumoral macroscopic veins were observed in 9/10 patients. No intracranial or spinal leptomeningeal dissemination was noted at diagnosis.

CONCLUSIONS

CNS tumors with a BCL6 corepressor gene internal tandem duplication present as large intra-axial peripheral masses with well-defined borders, no edema, restricted diffusion, weak contrast enhancement, frequent central necrosis, hemorrhage and calcifications, intratumoral veins, and no leptomeningeal dissemination at the time of diagnosis. Knowledge of these imaging characteristics may aid in histologic, genomic, and molecular profiling of brain tumors in young children.

MBRS-47. RAPID MOLECULAR SUBGROUPING OF MEDULLOBLASTOMA BASED ON DNA METHYLATION BY NANOPORE SEQUENCING

Medulloblastoma (MB) can be classified into four molecular subgroups (WNT group, SHH group, group 3, and group 4). The gold standard of assignment of molecular subgroup through DNA methylation profiling uses Illumina EPIC array. However, this tool has some limitation in terms of cost and timing, in order to get the results soon enough for clinical use. We present an alternative DNA methylation assay based on nanopore sequencing efficient for rapid, cheaper, and reliable subgrouping of clinical MB samples. Low-depth whole genome with long-read single-molecule nanopore sequencing was used to simultaneously assess copy number profile and MB subgrouping based on DNA methylation. The DNA methylation data generated by Nanopore sequencing were compared to a publicly available reference cohort comprising over 2,800 brain tumors including the four subgroups of MB (Capper et al. Nature; 2018) to generate a score that estimates a confidence with a tumor group assignment. Among the 24 MB analyzed with nanopore sequencing (six WNT, nine SHH, five group 3, and four group 4), all of them were classified in the appropriate subgroup established by expression-based Nanostring subgrouping. In addition to the subgrouping, we also examine the genomic profile. Furthermore, all previously identified clinically relevant genomic rearrangements (mostly MYC and MYCN amplifications) were also detected with our assay. In conclusion, we are confirming the full reliability of nanopore sequencing as a novel rapid and cheap assay for methylation-based MB subgrouping. We now plan to implement this technology to other embryonal tumors of the central nervous system.

QOL-17. BIOLOGICAL CORRELATES OF QUALITY OF SURVIVAL AND NEUROCOGNITIVE OUTCOMES IN MEDULLOBLASTOMA; A META-ANALYSIS OF THE SIOP-UKCCSG-PNET3 AND HIT-SIOP-PNET4 TRIALS

Relationships between biological factors (genetic, tumour molecular subgroup) and neurocognitive/Quality of Survival (QoS) outcomes in medulloblastoma survivors are emerging, based on studies of limited retrospective cohorts. Integrated investigations of the medulloblastoma late-effects pathway (considering biological, clinical and treatment factors), using larger clinically-controlled cohorts, are now essential to determine their independent significance and potential for clinical application. In a combined cohort of SIOP-UKCCSG-PNET3 and HIT-SIOP-PNET4 patients (n=150), molecular subgroup (MB_WNT, MB_SHH, MB_Grp3, MB_Grp4) was assessed against QoS measures [health status: HUI3; emotional and behavioural difficulties: SDQ; Health-related Quality of Life (HrQoL): PedsQL]. Additionally, in DNA remaining from HIT-SIOP-PNET4 (n=74), 39 candidate SNPs (involved in metabolism, DNA maintenance/repair, neural growth/repair and oxidative stress/inflammation) were genotyped by multiplexed MALDI-TOF MassArray and assessed against Wechsler Intelligence Scale (WISC) scores. Molecular subgroup was significantly associated with HrQoL and health status in univariate analyses; MB_Grp4 predicted significantly worse outcomes than MB_SHH and MB_Grp3 (p<0.05), but not in multivariate analyses taking into consideration other significant and reported QoS predictors (e.g. treatment, gender, age). In contrast, 6 SNPs were significantly associated with ≥1 WISC domain; 4/6 showed associations across domains. 3 SNPs were independently prognostic in multivariate analyses, and further significant associations were apparent at the gene (BDNF, APOE) and pathway (folate) level. This cross-discipline, international study encompassing two medulloblastoma trials has identified relationships between molecular subgroup, genotype and survivorship outcomes. These findings now require assessment in larger series, to inform our understanding of medulloblastoma survivorship outcomes and impact future disease management strategies.

MBRS-37. RECURRENT ACTIVATING MUTATIONS OF AKT GENES IN WNT-ACTIVATED MEDULLOBLASTOMAS

Medulloblastoma (MB) can be classified into four distinct molecular subgroups (WNT group, SHH group, group 3, and group 4). Medulloblastoma of the WNT subgroup (WNT-MB) are commonly associated with favorable prognosis. Prospective molecular analysis based on a combination of CGH-array, targeted NGS and Nanostring-based subgrouping on 272 MB was conducted. Our custom targeted NGS panel of 75 genes includes genes recurrently affected in MB together with actionable genes with therapeutic purpose including some involved in the PIK3/AKT signaling pathway. Among the 272 MB analyzed, 26 cases (9.6%) belonged to the WNT subgroup based on CTNNB1 mutations, monosomy of chromosome 6 and Nanostring-based molecular subgrouping. Our targeted NGS revealed three hotspot activating mutations in AKT3 in WNT-MB and only one cases in another MB subgroup (in a group 4 MB; among the 33 cases of confirmed group 4 MB in our cohort). We subsequently performed Sanger sequencing of the hotspot Glu17 codon of AKT1, AKT2, and AKT3 in 42 additional WNT-MB. This analysis revealed six additional activating mutations of AKT genes (four AKT3 and two AKT1 hotspots mutations) in WNT-MB. Altogether, we report 9/68 (13.2%) cases of WNT-MB with AKT genes mutations (two mutations in AKT1 and seven mutations in AKT3). Our molecular analysis revealed AKT hotspot mutations that presumably activate the PIK3/AKT signaling pathway in WNT-MB. Even though WNT-MB is the subgroup of MB with the most favorable prognosis, this result emphasizes a possibility of targeted therapy that need to be further explored in vitro and in vivo.

Focal Areas of High Signal Intensity in Children with Neurofibromatosis Type 1: Expected Evolution on MRI

BACKGROUND AND PURPOSE

Focal areas of high signal intensity are T2WI/T2-FLAIR hyperintensities frequently found on MR imaging of children diagnosed with neurofibromatosis type 1, often thought to regress spontaneously during adolescence or puberty. Due to the risk of tumor in this population, some focal areas of high signal intensity may pose diagnostic problems. The objective of this study was to assess the characteristics and temporal evolution of focal areas of high signal intensity in children with neurofibromatosis type 1 using long-term follow-up with MR imaging.

MATERIALS AND METHODS

We retrospectively examined the MRIs of children diagnosed with neurofibromatosis type 1 using the National Institutes of Health Consensus Criteria (1987), with imaging follow-up of at least 4 years. We recorded the number, size, and surface area of focal areas of high signal intensity according to their anatomic distribution on T2WI/T2-FLAIR sequences. A generalized mixed model was used to analyze the evolution of focal areas of high signal intensity according to age, and separate analyses were performed for girls and boys.

RESULTS

Thirty-nine patients (ie, 285 MR images) with a median follow-up of 7 years were analyzed. Focal areas of high signal intensity were found in 100% of patients, preferentially in the infratentorial white matter (35% cerebellum, 30% brain stem) and in the capsular lenticular region (22%). They measured 15 mm in 95% of cases. They appeared from the age of 1 year; increased in number, size, and surface area to a peak at the age of 7; and then spontaneously regressed by 17 years of age, similarly in girls and boys.

CONCLUSIONS

Focal areas of high signal intensity are mostly small (<15 mm) abnormalities in the posterior fossa or capsular lenticular region. Our results suggest that the evolution of focal areas of high signal intensity is not related to puberty with a peak at the age of 7 years. Knowledge of the predictive evolution of focal areas of high signal intensity is essential in the follow-up of children with neurofibromatosis type 1.

RARE-45. ACTIVITY OF LAROTRECTINIB IN TRK FUSION CANCER PATIENTS WITH PRIMARY CENTRAL NERVOUS SYSTEM TUMORS

BACKGROUND

TRK fusions are oncogenic drivers of a variety of tumors, many of which can involve the central nervous system (CNS). Larotrectinib is a selective TRK inhibitor FDA-approved for the treatment of TRK fusion cancers (Drilon et al., NEJM 2018). Here we report on the clinical activity of larotrectinib in an expanded set of TRK fusion-positive primary CNS tumors.

METHODS

Patients with primary CNS tumors harboring a TRK fusion treated with larotrectinib on two clinical trials (NCT02637687 and NCT02576431) were identified by local molecular testing. Larotrectinib was administered until disease progression, withdrawal, or unacceptable toxicity. Disease status was investigator assessed (RANO). Data cutoff: February 19, 2019.

RESULTS

18 patients with various histological types of glial tumors (11 high-grade, 4 low-grade, 3 unknown) were identified. The patients had gene fusions involving NTRK2 (n=13), NTRK1 (n=2) and NTRK3 (n=2); one was not determined. Median age was 10 years (range 1–79); 14 patients were pediatric (< 18). In 14 evaluable patients, the objective response rate was 36% (2 CR, 3 PR), with responses seen in high- and low-grade disease and across histologies. Nine patients had SD. The 24-week disease control rate was 71%. The duration of treatment ranged from 0.03+ to 16.6+ months. One patient (3.7 years old) with glioblastoma progressed after 5.5 months on larotrectinib. Sequencing revealed a solvent front mutation and the patient was subsequently enrolled in compassionate use protocol for BAY2731954 (formerly known as LOXO-195).

CONCLUSION

Larotrectinib is active in patients with TRK fusion cancer with intracranial disease. Confirmed responses and durable disease control were seen in primary CNS tumors of various grades and histologies. These results further support expanded testing for NTRK gene fusions in patients with primary CNS tumors.

Indications and results of diagnostic biopsy in pediatric renal tumors: A retrospective analysis of 317 patients with critical review of SIOP guidelines

OBJECTIVES

According to the Renal Tumor Study Group (RTSG) of the International Society of Paediatric Oncology (SIOP), diagnostic biopsy of renal tumors prior to neoadjuvant chemotherapy is not mandatory unless the presentation is atypical for a Wilms tumor (WT). This study addresses the relevance of this strategy as well as the accuracy and safety of image-guided needle biopsy.

METHODS

Clinical, radiological, and pathological data from 317 children (141 males/176 females, mean age: 4 years, range, 0-17.6) consecutively treated in one SIOP-affiliated institution were retrospectively analyzed.

RESULTS

Presumptive chemotherapy for WT was decided for 182 patients (57% of the cohort), 24 (8%) were operated upfront, and 111 (35%) were biopsied at diagnosis. A non-WT was confirmed after surgery in 5/182 (3%), 11/24 (46%), and 28/111 (25%), respectively. Age at diagnosis was the most commonly (46%) used criterion to go for biopsy but a nine-year threshold should be retrospectively considered more relevant. Tumor volumes of clear cell sarcoma of the kidney and WT were significantly higher than those of other tumors (P = 0.002). The agreement between core-needle biopsy (CNB) and final histology was 99%. No significant morbidity was associated with CNB.

CONCLUSION

The use of SIOP criteria to identify patients eligible for presumptive WT neoadjuvant chemotherapy or upfront surgery avoided biopsy in 65% of children and led to a 97% rate of appropriate preoperative chemotherapy. Image-guided CNB is a safe and accurate diagnostic procedure. The relevance of SIOP biopsy criteria might be improved by using an older age threshold (9 years instead of 6 years) and by adding initial tumor volume.

Ovarian tissue cryopreservation for fertility preservation in 418 girls and adolescents up to 15 years of age facing highly gonadotoxic treatment. Twenty years of experience at a single center

INTRODUCTION

The preservation of fertility is an integral part of care of children requiring gonadotoxic treatments for cancer or non-malignant diseases. In France, the cryopreservation of ovarian tissue has been considered and has been offered as a clinical treatment since its inception. The aim of this study is to review 20 years of activity in fertility preservation by ovarian tissue cryopreservation (OTC) for children and the feasibility of oocyte isolation and cryopreservation from the ovarian tissue at a single center.

MATERIAL AND METHODS

Retrospective study including patients aged 15 years or younger who underwent OTC, combined for some with oocyte cryopreservation of isolated oocytes, before a highly gonadotoxic treatment for malignant or non-malignant disease was initiated. We describe the evolution of activities in our program for fertility preservation and patient characteristics at the time of OTC and follow up.

RESULTS

From April 1998 to December 2018, 418 girls and adolescents younger than 15 years of age underwent OTC, representing 40.5% of all females who have had ovarian tissue cryopreserved at our center. In all, 313 patients had malignant diseases and 105 had benign conditions. Between November 2009 and July 2013, oocytes were isolated and also cryopreserved in 50 cases. The mean age of patients was 6.9 years (range 0.3-15). The most frequent diagnoses in this cohort included neuroblastoma, acute leukemia and hemoglobinopathies; neuroblastoma being the most common diagnosis in very young patients. During follow up, three patients requested the use of their cryopreserved ovarian tissue. All had undergone ovarian tissue transplantation, one for puberty induction and the two others for restoring fertility. So far, no pregnancies have been achieved. Eighty-four patients who had OTC died.

CONCLUSIONS

Ovarian tissue cryopreservation is the only available technique for preserving fertility of girls. To our knowledge this is the largest series of girls and adolescents younger than 15 years so far reported on procedures of OTC before highly gonadotoxic treatment in a single center.

Abstract LB-324: A whole chromosome aberration phenotype in non-WNT/non-SHH tumors predicts outcome within standard-risk medulloblastomas from the HIT-SIOP-PNET4 clinical trial

Introduction: Standard-risk medulloblastoma (SR-MB; 50-60% of patients) is currently defined by the absence of high-risk (e.g. metastatic disease, large-cell/anaplastic histology, MYC amplification) disease features. 75-85% survival rates are achieved, however the identification and validation of novel prognostic biomarkers will be essential to improve risk-adapted therapies, aimed at increased survival and reduced treatment-related late-effects.

Experimental procedures: We undertook comprehensive analysis of the pan-European HIT-SIOP-PNET4 prospective clinical trial (2001-2006; age 4-21 years at diagnosis), encompassing central clinical and radiological review, and annotation of molecular pathological features to the WHO (2016) classification. Methods were developed and/or adapted to assess methylation-dependent molecular subgroup (MassArray), copy number aberrations (molecular inversion probe array) and mutational status in scant archival material previously refractory to analysis (n=136). Independent prognostic markers/predictive models for non-WNT/non-SHH patients (n=91) were identified by multivariate analyses, and validated in a representative independent cohort (n=70).

Results: WNT (n=28; 21%) and Group 4 (n=76; 56%) tumors were enriched in SR-MB compared to published disease-wide estimates. Favorable-risk WNT disease was confirmed in patients &lt;16.0 years at diagnosis. All events in SHH (4 of 17) occurred in tumors with TP53 mutation and/or chr17p loss. In non-WNT/non-SHH tumors, a novel whole chromosomal aberration (WCA) phenotype characterized by chr7 gain, chr8 loss, and/or chr11 loss, was identified in 42% of patients (38 of 91). This phenotype predicted an excellent prognosis (100% 5-year PFS) and its incorporation into novel survival models out-performed current risk-stratification schemes for SR-MB.

Conclusion: A favorable-risk WCA phenotype identifies a large proportion (42%) of non-WNT/non-SHH SR-MB patients for whom therapy de-escalation should be considered in future biomarker-driven risk-adapted clinical trials; remaining patients (58%; 68% 5-year PFS) might benefit from more intensive and/or novel therapies.

Citation Format: Tobias Goschzik, Ed C. Schwalbe, Debbie Hicks, Dominique Figarella-Branger, Francois Doz, Stefan Rutkowski, Goran Gustafsson, Birgitta Lannering, Torsten Pietsch, Steve C. Clifford. A whole chromosome aberration phenotype in non-WNT/non-SHH tumors predicts outcome within standard-risk medulloblastomas from the HIT-SIOP-PNET4 clinical trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-324.

Minimal methylation classifier (MIMIC): A novel method for derivation and rapid diagnostic detection of disease-associated DNA methylation signatures

Rapid and reliable detection of disease-associated DNA methylation patterns has major potential to advance molecular diagnostics and underpin research investigations. We describe the development and validation of minimal methylation classifier (MIMIC), combining CpG signature design from genome-wide datasets, multiplex-PCR and detection by single-base extension and MALDI-TOF mass spectrometry, in a novel method to assess multi-locus DNA methylation profiles within routine clinically-applicable assays. We illustrate the application of MIMIC to successfully identify the methylation-dependent diagnostic molecular subgroups of medulloblastoma (the most common malignant childhood brain tumour), using scant/low-quality samples remaining from the most recently completed pan-European medulloblastoma clinical trial, refractory to analysis by conventional genome-wide DNA methylation analysis. Using this approach, we identify critical DNA methylation patterns from previously inaccessible cohorts, and reveal novel survival differences between the medulloblastoma disease subgroups with significant potential for clinical exploitation.

Early phase clinical trials of anticancer agents in children and adolescents - an ITCC perspective

In the past decade, the landscape of drug development in oncology has evolved dramatically; however, this paradigm shift remains to be adopted in early phase clinical trial designs for studies of molecularly targeted agents and immunotherapeutic agents in paediatric malignancies. In drug development, prioritization of drugs on the basis of knowledge of tumour biology, molecular 'drivers' of disease and a drug's mechanism of action, and therapeutic unmet needs are key elements; these aspects are relevant to early phase paediatric trials, in which molecular profiling is strongly encouraged. Herein, we describe the strategy of the Innovative Therapies for Children with Cancer (ITCC) Consortium, which advocates for the adoption of trial designs that enable uninterrupted patient recruitment, the extrapolation from studies in adults when possible, and the inclusion of expansion cohorts. If a drug has neither serious dose-related toxicities nor a narrow therapeutic index, then studies should generally be started at the adult recommended phase II dose corrected for body surface area, and act as dose-confirmation studies. The use of adaptive trial designs will enable drugs with promising activity to progress rapidly to randomized studies and, therefore, will substantially accelerate drug development for children and adolescents with cancer.

Risk stratification of childhood medulloblastoma in the molecular era: the current consensus

Historical risk stratification criteria for medulloblastoma rely primarily on clinicopathological variables pertaining to age, presence of metastases, extent of resection, histological subtypes and in some instances individual genetic aberrations such as MYC and MYCN amplification. In 2010, an international panel of experts established consensus defining four main subgroups of medulloblastoma (WNT, SHH, Group 3 and Group 4) delineated by transcriptional profiling. This has led to the current generation of biomarker-driven clinical trials assigning WNT tumors to a favorable prognosis group in addition to clinicopathological criteria including MYC and MYCN gene amplifications. However, outcome prediction of non-WNT subgroups is a challenge due to inconsistent survival reports. In 2015, a consensus conference was convened in Heidelberg with the objective to further refine the risk stratification in the context of subgroups and agree on a definition of risk groups of non-infant, childhood medulloblastoma (ages 3-17). Published and unpublished data over the past 5 years were reviewed, and a consensus was reached regarding the level of evidence for currently available biomarkers. The following risk groups were defined based on current survival rates: low risk (>90 % survival), average (standard) risk (75-90 % survival), high risk (50-75 % survival) and very high risk (<50 % survival) disease. The WNT subgroup and non-metastatic Group 4 tumors with whole chromosome 11 loss or whole chromosome 17 gain were recognized as low-risk tumors that may qualify for reduced therapy. High-risk strata were defined as patients with metastatic SHH or Group 4 tumors, or MYCN-amplified SHH medulloblastomas. Very high-risk patients are Group 3 with metastases or SHH with TP53 mutation. In addition, a number of consensus points were reached that should be standardized across future clinical trials. Although we anticipate new data will emerge from currently ongoing and recently completed clinical trials, this consensus can serve as an outline for prioritization of certain molecular subsets of tumors to define and validate risk groups as a basis for future clinical trials.

Conservative treatment of retinoblastoma: a prospective phase II randomized trial of neoadjuvant chemotherapy followed by local treatments and chemothermotherapy

PurposeIntraocular retinoblastoma treatments often combine chemotherapy and focal treatments. A first prospective protocol of conservative treatments in our institution showed the efficacy of the use of two courses of chemoreduction with etoposide and carboplatin, followed by chemothermotherapy using carboplatin as a single agent and diode laser. In order to decrease the possible long-term toxicity of chemotherapy due to etoposide, a randomized neoadjuvant phase II protocol was conducted using vincristine-carboplatin vs etoposide-carboplatin.Patients and methodsThe study was proposed when initial tumor characteristics did not allow front-line local treatments. Patients included in this phase II noncomparative randomized study of neoadjuvant chemotherapy received vincristin-carboplatin (new arm) vs etoposide-carboplatin (our reference arm). They were subsequently treated by local treatments and chemothermotherapy. Primary end point was the need for secondary enucleation or external beam radiotherapy (EBRT) not exceeding 40% at 2 years.ResultsA total of 65 eyes in 55 children were included in the study (May 2004 to August 2009). Of these, 32 eyes (27 children) were treated in the arm etoposide-carboplatin and 33 eyes (28 children) in the arm vincristin-carboplatin. At 2 years after treatment, 23/33 (69.7%) eyes were treated and salvaged without EBRT or enucleation in the arm vincristin-carboplatin and 26/32 (81.2%) in the arm etoposide-carboplatin.ConclusionEven if the two treatment arms could be considered as sufficiently active according to the study decision rules, neoadjuvant chemotherapy by two cycles of vincristine-carboplatin followed by chemothermotherapy appear to offer less optimal local control than the etoposide-carboplatin combination.

Genome sequencing of SHH medulloblastoma predicts genotype-related response to smoothened inhibition

Smoothened (SMO) inhibitors recently entered clinical trials for sonic-hedgehog-driven medulloblastoma (SHH-MB). Clinical response is highly variable. To understand the mechanism(s) of primary resistance and identify pathways cooperating with aberrant SHH signaling, we sequenced and profiled a large cohort of SHH-MBs (n = 133). SHH pathway mutations involved PTCH1 (across all age groups), SUFU (infants, including germline), and SMO (adults). Children >3 years old harbored an excess of downstream MYCN and GLI2 amplifications and frequent TP53 mutations, often in the germline, all of which were rare in infants and adults. Functional assays in different SHH-MB xenograft models demonstrated that SHH-MBs harboring a PTCH1 mutation were responsive to SMO inhibition, whereas tumors harboring an SUFU mutation or MYCN amplification were primarily resistant.

Malformations, genetic abnormalities, and Wilms tumor

BACKGROUND

Wilms Tumor (WT) can occur in association with tumor predisposition syndromes and/or with clinical malformations. These associations have not been fully characterized at a clinical and molecular genetic level. This study aims to describe clinical malformations, genetic abnormalities, and tumor predisposition syndromes in patients with WT and to propose guidelines regarding indications for clinical and molecular genetic explorations.

PROCEDURE

This retrospective study analyzed clinical abnormalities and predisposition syndromes among 295 patients treated for WT between 1986 and 2009 in a single pediatric oncological center.

RESULTS

Clinically identified malformations and predisposition syndromes were observed in 52/295 patients (17.6%). Genetically proven tumor predisposition syndromes (n = 14) frequently observed were syndromes associated with alterations of the chromosome WT1 region such as WAGR (n = 6) and Denys-Drash syndromes (n = 3), syndromes associated with alterations of the WT2 region (Beckwith-Wiedeman syndrome, n = 3), and Fanconi anemia (n = 2). Hemihypertrophy and genito-urinary malformations (n = 12 and n = 16, respectively) were the most frequently identified malformations. Other different syndromes or malformations (n = 10) were less frequent. Median age of WT diagnosis was significantly earlier for children with malformations than those without (27 months vs. 37 months, P = 0.0009). There was no significant difference in terms of 5-year EFS and OS between WT patients without or with malformations.

CONCLUSIONS

The frequency of malformations observed in patients with WT underline the need of genetic counseling and molecular genetic explorations for a better follow-up of these patients, with a frequently good outcome. A decisional tree, based on clinical observations of patients with WT, is proposed to guide clinicians for further molecular genetic explorations.