TRIM28 inactivation in epithelial nephroblastoma is frequent and often associated with predisposing TRIM28 germline variants.

Wilms tumors (WTs) are histologically diverse childhood cancers with variable contributions of blastema, stroma, and epithelia. A variety of cancer genes operate in WTs, including the tripartite-motif-containing-28 gene (TRIM28). Case reports and small case series suggest that TRIM28 mutations are associated with epithelial morphology and WT predisposition. Here, we systematically investigated the prevalence of TRIM28 inactivation and predisposing mutations in a cohort of 126 WTs with >2/3 epithelial cells, spanning 20 years of biobanking in the German SIOP93-01/GPOH and SIOP2001/GPOH studies. Overall, 44.4% (56/126) cases exhibited loss of TRIM28 by immunohistochemical staining. Of these, 48 could be further analyzed molecularly, revealing TRIM28 sequence variants in each case - either homozygous (~2/3) or heterozygous with epigenetic silencing of the second allele (~1/3). The majority (80%) of the mutations resulted in premature stops and frameshifts. In addition, we detected missense mutations and small deletions predicted to destabilize the protein through interference with folding of key structural elements such as the zinc-binding clusters of the RING, B-box-2, and PHD domains or the central coiled-coil region. TRIM28-mutant tumors otherwise lacked WT-typical IGF2 alterations or driver events, except for rare TP53 progression events that occurred with expected frequency. Expression profiling identified TRIM28-mutant tumors as a homogeneous subset of epithelial WTs that mostly present with stage I disease. There was a high prevalence of perilobar nephrogenic rests, putative precursor lesions, that carried the same biallelic TRIM28 alterations in 7/7 cases tested. Importantly, 46% of the TRIM28 mutations were present in blood cells or normal kidney tissue, suggesting germline events or somatic mosaicism, partly supported by family history. Given the high prevalence of predisposing variants in TRIM28-driven WT, we suggest that immunohistochemical testing of TRIM28 be integrated into diagnostic practice as the management of WT in predisposed children differs from that with sporadic tumors. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Irinotecan and temozolomide in combination with dasatinib and rapamycin versus irinotecan and temozolomide for patients with relapsed or refractory neuroblastoma (RIST-rNB-2011): a multicentre, open-label, randomised, controlled, phase 2 trial.

BACKGROUND: Neuroblastoma is the most common extracranial solid tumour in children. Relapsed or refractory neuroblastoma is associated with a poor outcome. We assessed the combination of irinotecan-temozolomide and dasatinib-rapamycin (RIST) in patients with relapsed or refractory neuroblastoma. METHODS: The multicentre, open-label, randomised, controlled, phase 2, RIST-rNB-2011 trial recruited from 40 paediatric oncology centres in Germany and Austria. Patients aged 1-25 years with high-risk relapsed (defined as recurrence of all stage IV and MYCN amplification stages, after response to treatment) or refractory (progressive disease during primary treatment) neuroblastoma, with Lansky and Karnofsky performance status at least 50%, were assigned (1:1) to RIST (RIST group) or irinotecan-temozolomide (control group) by block randomisation, stratified by MYCN status. We compared RIST (oral rapamycin [loading 3 mg/m2 on day 1, maintenance 1 mg/m2 on days 2-4] and oral dasatinib [2 mg/kg per day] for 4 days with 3 days off, followed by intravenous irinotecan [50 mg/m2 per day] and oral temozolomide [150 mg/m2 per day] for 5 days with 2 days off; one course each of rapamycin-dasatinib and irinotecan-temozolomide for four cycles over 8 weeks, then two courses of rapamycin-dasatinib followed by one course of irinotecan-temozolomide for 12 weeks) with irinotecan-temozolomide alone (with identical dosing as experimental group). The primary endpoint of progression-free survival was analysed in all eligible patients who received at least one course of therapy. The safety population consisted of all patients who received at least one course of therapy and had at least one post-baseline safety assessment. This trial is registered at ClinicalTrials.gov, NCT01467986, and is closed to accrual. FINDINGS: Between Aug 26, 2013, and Sept 21, 2020, 129 patients were randomly assigned to the RIST group (n=63) or control group (n=66). Median age was 5·4 years (IQR 3·7-8·1). 124 patients (78 [63%] male and 46 [37%] female) were included in the efficacy analysis. At a median follow-up of 72 months (IQR 31-88), the median progression-free survival was 11 months (95% CI 7-17) in the RIST group and 5 months (2-8) in the control group (hazard ratio 0·62, one-sided 90% CI 0·81; p=0·019). Median progression-free survival in patients with amplified MYCN (n=48) was 6 months (95% CI 4-24) in the RIST group versus 2 months (2-5) in the control group (HR 0·45 [95% CI 0·24-0·84], p=0·012); median progression-free survival in patients without amplified MYCN (n=76) was 14 months (95% CI 9-7) in the RIST group versus 8 months (4-15) in the control group (HR 0·84 [95% CI 0·51-1·38], p=0·49). The most common grade 3 or worse adverse events were neutropenia (54 [81%] of 67 patients given RIST vs 49 [82%] of 60 patients given control), thrombocytopenia (45 [67%] vs 41 [68%]), and anaemia (39 [58%] vs 38 [63%]). Nine serious treatment-related adverse events were reported (five patients given control and four patients given RIST). There were no treatment-related deaths in the control group and one in the RIST group (multiorgan failure). INTERPRETATION: RIST-rNB-2011 demonstrated that targeting of MYCN-amplified relapsed or refractory neuroblastoma with a pathway-directed metronomic combination of a multkinase inhibitor and an mTOR inhibitor can improve progression-free survival and overall survival. This exclusive efficacy in MYCN-amplified, relapsed neuroblastoma warrants further investigation in the first-line setting. FUNDING: Deutsche Krebshilfe.

Spontaneous remission and loss of monosomy 7: a window of opportunity for young children with SAMD9L syndrome.

Monosomy 7 is the most common cytogenetic abnormality in pediatric myelodysplastic syndrome (MDS) and associated with a high risk of disease progression. However, in young children, spontaneous loss of monosomy 7 with concomitant hematologic recovery has been described, especially in the presence of germline mutations in SAMD9 and SAMD9L genes. Here, we report on our experience of close surveillance instead of upfront hematopoietic stem cell transplantation (HSCT) in seven patients diagnosed with SAMD9L syndrome and monosomy 7 at a median age of 0.6 years (range, 0.4-2.9). Within 14 months from diagnosis, three children experienced spontaneous hematological remission accompanied by a decrease in monosomy 7 clone size. Subclones with somatic SAMD9L mutations in cis were identified in five patients, three of whom attained hematological remission. Two patients acquired RUNX1 and EZH2 mutations during the observation period, of whom one progressed to myelodysplastic syndrome with excess of blasts (MDS-EB). Four patients underwent allogeneic HSCT at a median time of 26 months (range, 14-40) from diagnosis for MDSEB, necrotizing granulomatous lymphadenitis, persistent monosomy 7, and severe neutropenia. At last follow-up, six patients were alive, while one passed away due to transplant-related causes. These data confirm previous observations that monosomy 7 can be transient in young children with SAMD9L syndrome. However, they also indicate that delaying HSCT poses a substantial risk of severe infection and disease progression. Finally, surveillance of patients with SAMD9L syndrome and monosomy 7 is critical to define the evolving genetic landscape and to determine the appropriate timing of HSCT (clinicaltrials gov. Identifier: NCT00662090).

Approaches for bridging therapy prior to chimeric antigen receptor T cells for relapsed/refractory acute lymphoblastic B-lineage leukaemia in children and young adults.

The ongoing development of immunotherapies, including chimeric antigen receptor (CAR) T cells, has revolutionized cancer treatment. In paediatric relapsed/refractory B-lineage acute leukaemia antiCD19-CARs induced impressive initial response rates, with event-free survival plateauing at 30-50% in long-term follow-up data. During the interval between diagnosis of relapse or refractoriness and CAR T cell infusion, patients require a bridging therapy. To date, this therapy has consisted of highly variable approaches based on local experience. Here, in an European collaborative effort of paediatric and adult haematologists, we summarise current knowledge with the aim of establishing a guidance for bridging therapy. This includes treatment strategies for different patient subgroups, the advantages and disadvantages of low- and highintensity regimens, and the potential impact of bridging therapy on outcome after CAR T cell infusion. This guidance is a step towards a cross-institutional harmonization of bridging therapy, including personalized approaches. This will allow better comparability of clinical data and increase the level of evidence for the treatment of children and young adults with relapsed/refractory B-lineage ALL until CAR T cell infusion.

NUT carcinoma in pediatric patients: Characteristics, therapeutic regimens, and outcomes of 11 cases registered with the German Registry for Rare Pediatric Tumors (STEP).

BACKGROUND AND AIMS: Nuclear protein of the testis (NUT) carcinoma (NC) is a rare and highly aggressive tumor defined by the presence of a somatic NUTM1 rearrangement, occurring mainly in adolescents and young adults. We analyzed the clinical and biological features of German pediatric patients (≤18 years) with NC. METHODS: This study describes the characteristics and outcome of 11 children with NC registered in the German Registry for Rare Pediatric Tumors (STEP). RESULTS: Eleven patients with a median age of 13.2 years (range 6.6-17.8) were analyzed. Malignant misdiagnoses were made in three patients. Thoracic/mediastinal tumors were found to be the primary in six patients, head/neck in four cases; one patient had multifocal tumor with an unknown primary. All patients presented with regional lymph node involvement, eight patients (72.7%) with distant metastases. Seven patients underwent surgery, eight radiotherapy with curative intent; polychemotherapy was administered in all patients. Novel treatment strategies including immunotherapy, targeted therapies, and virotherapy were applied in three patients. Median event-free survival and overall survival were 1.5 and 6.5 months, respectively. CONCLUSIONS: Every undifferentiated or poorly differentiated carcinoma should undergo testing for the specific rearrangement of NUTM1, in order to initiate an intense therapeutic regimen as early as possible. As in adults, only few pediatric patients with NC achieve prolonged survival. Thus, novel therapeutic strategies should be included and tested in clinical trials.

Survivors of infant atypical teratoid/rhabdoid tumors present with severely impaired cognitive functions especially for fluid intelligence and visual processing: data from the German brain tumor studies.

BACKGROUND: The contribution of tumor type, multimodal treatment, and other patient-related factors upon long-term cognitive sequelae in infant brain tumor survivors remains undefined. We add our retrospective analysis of neuropsychological and quality of survival (QoS) outcome data of survivors of atypical teratoid/rhabdoid tumors (ATRT) and extracranial malignant rhabdoid tumors of the soft tissues (eMRT) and kidneys (RTK) treated within the same framework. Neuropsychological data from children with ATRT were compared to data from children with non-irradiated low-grade glioma (LGG). PATIENTS AND METHODS: Following surgery, patients (0-36 months at diagnosis) had received radio-chemotherapy (up to 54 Gy; ATRT: n = 13; eMRT/RTK: n = 7), chemotherapy only (LGG: n = 4; eMRT/RTK: n = 1) or had been observed (LGG: n = 11). Neuropsychological evaluation employing comparable tests was performed at median 6.8 years (ATRT), 6.6 years (eMRT/RTK), and 5.2 years (LGG) post diagnosis. RESULTS: We detected sequelae in various domains for all tumor types. Group comparison showed impairments, specifically in fluid intelligence (p = .041; d = 1.11) and visual processing (p = .001; d = 2.09) in ATRT patients when compared to LGG patients. Results for psychomotor speed and attention abilities were significantly below the norm for both groups (p < .001-.019; d = 0.79-1.90). Diagnosis predicted impairments of cognitive outcome, while sex- and age-related variables did not. QoS outcome for all rhabdoid patients displayed impairments mainly in social (p = .008; d = 0.74) and school functioning (p = .048; d = 0.67), as well as lower overall scores in psychosocial functioning (p = .023; d = 0.78) and quality of life (p = .006; d = 0.79) compared to healthy controls. CONCLUSION: Survivors of infant ATRT experience various late effects in cognition and QoS following multimodal treatment, while infant LGG patients without radiotherapy demonstrated comparable impairments in psychomotor and attention abilities. Early onset and multimodal treatment of rhabdoid tumors require close monitoring of neuropsychological and QoS sequelae.

SWI/SNF-deficient tumors of the central nervous system: An update.

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant tumor of the central nervous system characterized by biallelic inactivation of SWI/SNF chromatin remodeling complex members SMARCB1/INI1 or (rarely) SMARCA4/BRG1. Most high-grade central nervous system lesions showing loss of nuclear SMARCB1 or SMARCA4 protein expression can indeed be categorized as AT/RT. However, some high-grade lesions have been identified, whose clinical and/or molecular features justify separation from AT/RT. Furthermore, other recently described tumor types such as desmoplastic myxoid tumor, SMARCB1-mutant, and low-grade diffusely infiltrative tumor, SMARCB1-mutant, may even manifest as low-grade lesions. Here, we review recent developments in the definition of the molecular landscape of AT/RT and give an update on other rare high- and low-grade SWI/SNF-deficient central nervous system tumors.

Impact of regional SARS-CoV-2 proceedings on changes in diagnoses of pediatric malignancies in Bavaria during the COVID-19 pandemic.

The COVID-19 pandemic affected daily life significantly and had massive consequences for healthcare systems with tremendous regional differences. This retrospective study aimed to investigate whether the pandemic and resulting societal changes impacted the diagnosis of pediatric malignancies in a distinct region. Pediatric cancer cases in Bavaria (2016-2021) and SARS-CoV-2 proceedings during the peak phase of the pandemic (2020-2021) were retrospectively analyzed. All new diagnoses of pediatric malignancies reported from cancer centers in Bavaria were included. Clinical data from pre-pandemic years was compared to diagnoses made during the pandemic. Official SARS-CoV-2 reports were received from the Bavarian Health and Food Safety Authority and data on regional pandemic measures were obtained from the Healthcare Data Platform. With this design, a comprehensive analysis of the pandemic proceedings was performed. We found significantly decreased incidence-rate ratios for pediatric cancer diagnosis during the early spring peak of SARS-CoV-2 as it was observed in May during the pandemic, followed by non-significantly increased metastatic cancer diagnosis two months later. Additionally, the time-to-diagnosis of pediatric malignancies was significantly prolonged during the pandemic, and outpatient contacts were significantly reduced, although the availability of consultations remained the same. From our findings, we may hypothesize that there have been effects on pediatric cancer diagnosis during the COVID-19 pandemic at vulnerable times. Interpretation of changes remains speculative with potential causes from behavior patterns, such as hesitation, concerns, and potential societal changes during phases of public restrictions, rather than overwhelmed medical capacities. Nevertheless, specific awareness is needed to protect this patient population during potential future pandemics.

Rhabdoid tumors in patients conceived following ART: is there an association?

STUDY QUESTION: In children affected by rhabdoid tumors (RT), are there clinical, therapeutic, and/or (epi-)genetic differences between those conceived following ART compared to those conceived without ART? SUMMARY ANSWER: We detected a significantly elevated female predominance, and a lower median age at diagnosis, of children with RT conceived following ART (RT_ART) as compared to other children with RT. WHAT IS KNOWN ALREADY: Anecdotal evidence suggests an association of ART with RT. STUDY DESIGN, SIZE, DURATION: This was a multi-institutional retrospective survey. Children with RT conceived by ART were identified in our EU-RHAB database (n = 11/311 children diagnosed between January 2010 and January 2018) and outside the EU-RHAB database (n = 3) from nine different countries. A population-representative German EU-RHAB control cohort of children with RTs conceived without ART (n = 211) (EU-RHAB control cohort) during the same time period was used as a control cohort for clinical, therapeutic, and survival analyses. The median follow-up time was 11.5 months (range 0-120 months) for children with RT_ART and 18.5 months (range 0-153 months) for the EU-RHAB control cohort. PARTICIPANTS/MATERIALS, SETTING, METHODS: We analyzed 14 children with RT_ART diagnosed from January 2010 to January 2018. We examined tumors and matching blood samples for SMARCB1 mutations and copy number alterations using FISH, multiplex ligation-dependent probe amplification, and DNA sequencing. DNA methylation profiling of tumor and/or blood samples was performed using DNA methylation arrays and compared to respective control cohorts of similar age (n = 53 tumors of children with RT conceived without ART, and n = 38 blood samples of children with no tumor born small for gestational age). MAIN RESULTS AND THE ROLE OF CHANCE: The median age at diagnosis of 14 individuals with RT_ART was 9 months (range 0-66 months), significantly lower than the median age of patients with RT (n = 211) in the EU-RHAB control cohort (16 months (range 0-253), P = 0.03). A significant female predominance was observed in the RT_ART cohort (M:F ratio: 2:12 versus 116:95 in EU-RHAB control cohort, P = 0.004). Eight of 14 RT_ART patients were diagnosed with atypical teratoid rhabdoid tumor, three with extracranial, extrarenal malignant rhabdoid tumor, one with rhabdoid tumor of the kidney and two with synchronous tumors. The location of primary tumors did not differ significantly in the EU-RHAB control cohort (P = 0.27). Six of 14 RT_ART patients presented with metastases at diagnosis. Metastatic stage was not significantly different from that within the EU-RHAB control cohort (6/14 vs 88/211, P = 1). The incidence of pathogenic germline variants was five of the 12 tested RT_ART patients and, thus, not significantly different from the EU-RHAB control cohort (5/12 versus 36/183 tested, P = 0.35). The 5-year overall survival (OS) and event free survival (EFS) rates of RT_ART patients were 42.9 ± 13.2% and 21.4 ± 11%, respectively, and thus comparable to the EU-RHAB control cohort (OS 41.1 ± 3.5% and EFS 32.1 ± 3.3). We did not find other clinical, therapeutic, outcome factors distinguishing patients with RT_ART from children with RTs conceived without ART (EU-RHAB control cohort). DNA methylation analyses of 10 tumors (atypical teratoid RT = 6, extracranial, extrarenal malignant RT = 4) and six blood samples from RT_ART patients showed neither evidence of a general DNA methylation difference nor underlying imprinting defects, respectively, when compared to a control group (n = 53 RT samples of patients without ART, P = 0.51, n = 38 blood samples of patients born small for gestational age, P = 0.1205). LIMITATIONS, REASONS FOR CAUTION: RTs are very rare malignancies and our results are based on a small number of children with RT_ART. WIDER IMPLICATIONS OF THE FINDINGS: This cohort of patients with RT_ART demonstrated a marked female predominance, and a rather low median age at diagnosis even for RTs. Other clinical, treatment, outcome, and molecular factors did not differ from those conceived without ART (EU-RHAB control cohort) or reported in other series, and there was no evidence for imprinting defects. Long-term survival is achievable even in cases with pathogenic germline variants, metastatic disease at diagnosis, or relapse. The female preponderance among RT_ART patients is not yet understood and needs to be evaluated, ideally in larger international series. STUDY FUNDING/COMPETING INTEREST(S): M.C.F. is supported by the 'Deutsche Kinderkrebsstiftung' DKS 2020.10, by the 'Deutsche Forschungsgemeinschaft' DFG FR 1516/4-1 and by the Deutsche Krebshilfe 70113981. R.S. received grant support by Deutsche Krebshilfe 70114040 and for infrastructure by the KinderKrebsInitiative Buchholz/Holm-Seppensen. P.D.J. is supported by the Else-Kroener-Fresenius Stiftung and receives a Max-Eder scholarship from the Deutsche Krebshilfe. M.H. is supported by DFG (HA 3060/8-1) and IZKF Münster (Ha3/017/20). BB is supported by the 'Deutsche Kinderkrebsstiftung' DKS 2020.05. We declare no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Recurrent atypical teratoid/rhabdoid tumors (AT/RT) reveal discrete features of progression on histology, epigenetics, copy number profiling, and transcriptomics.

Atypical teratoid/rhabdoid tumors (AT/RT) are the most common malignant brain tumors manifesting in infancy. They split into four molecular types. The major three (AT/RT-SHH, AT/RT-TYR, and AT/RT-MYC) all carry mutations in SMARCB1, the fourth quantitatively smaller type is characterized by SMARCA4 mutations (AT/RT-SMARCA4). Molecular characteristics of disease recurrence or metastatic spread, which go along with a particularly dismal outcome, are currently unclear. Here, we investigated tumor tissue from 26 patients affected by AT/RT to identify signatures of recurrences in comparison with matched primary tumor samples. Microscopically, AT/RT recurrences demonstrated a loss of architecture and significantly enhanced mitotic activity as compared to their related primary tumors. Based on DNA methylation profiling, primary tumor and related recurrence were grossly similar, but three out of 26 tumors belonged to a different molecular type or subtype after second surgery compared to related primary lesions. Copy number variations (CNVs) differed in six cases, showing novel gains on chromosome 1q or losses of chromosome 10 in recurrences as the most frequent alterations. To consolidate these observations, our cohort was combined with a data set of unmatched primary and recurrent AT/RT, which demonstrated chromosome 1q gain and 10 loss in 18% (n = 7) and 11% (n = 4) of the recurrences (n = 38) as compared to 7% (n = 3) and 0% (n = 0) in the primary tumors (n = 44), respectively. Similar to the observations made by DNA methylation profiling, RNA sequencing of our cohort revealed AT/RT primary tumors and matched recurrences clustering closely together. However, a number of genes showed significantly altered expression in AT/RT-SHH recurrences. Many of them are known tumor driving growth factors, involved in embryonal development and tumorigenesis, or are cell-cycle-associated. Overall, our work identifies subtle molecular changes that occur in the course of the disease and that may help define novel therapeutic targets for AT/RT recurrences.