Pediatric acute promyelocytic leukemia and Fanconi anemia: Case report and literature review.

Acute promyelocytic leukemia (APL) represents 5%-10% of childhood acute myeloid leukemia (AML) and is the most curable subtype of AML. Fanconi anemia (FA) is one of the most common inherited bone marrow failure syndromes caused by biallelic pathogenic variants (PV) in specific DNA-repair genes. Biallelic PVs in FANCD1/BRCA2 (FA-D1) account for 3% of FA and are associated with early-onset leukemia and a high risk of solid tumors. We report a 4 year-old boy from non-consanguineous parents diagnosed with standard risk APL. This child had café-au-lait spots and an extra thumb remnant. Genomic sequencing revealed two PV in FANCD1/BRCA2 confirming a diagnosis of FA-D1. Chromosomal breakage studies were compatible with FA. Each parent carried one variant and had no personal history of cancer. Morphological then molecular remissions were achieved with all-trans retinoic acid and Arsenic trioxide. This patient underwent haploidentical stem cell transplant. In addition to our patient, a literature search revealed four additional patients with APL/FA, with a total of three patients with FA-D1. This raises the possibility of an association between such rare disorders. Practical management of APL in the setting of FA-D1 is discussed with an overview of current evidence and knowledge gaps.

Cost-effectiveness of the McGill interactive pediatric oncogenetic guidelines in identifying Li-Fraumeni syndrome in female patients with osteosarcoma.

BACKGROUND: Li-Fraumeni syndrome (LFS) is a penetrant cancer predisposition syndrome (CPS) associated with the development of many tumor types in young people including osteosarcoma and breast cancer (BC). The McGill Interactive Pediatric OncoGenetic Guidelines (MIPOGG) decision-support tool provides a standardized approach to identify patients at risk of CPSs. METHODS: We conducted a cost-utility analysis, from the healthcare payer perspective, to compare MIPOGG-guided, physician-guided, and universal genetic testing strategies to detect LFS in female patients diagnosed at an age of less than 18 years with osteosarcoma. We developed a decision tree and discrete-event simulation model to simulate the clinical and cost outcomes of the three genetic referral strategies on a cohort of female children diagnosed with osteosarcoma, especially focused on BC as subsequent cancer. Outcomes included BC incidence, quality-adjusted life-years (QALYs), healthcare costs, and incremental cost-utility ratios (ICURs). We conducted probabilistic and scenario analyses to assess the uncertainty surrounding model parameters. RESULTS: Compared to the physician-guided testing, the MIPOGG-guided strategy was marginally more expensive by $105 (-$516; $743), but slightly more effective by 0.003 (-0.04; 0.045) QALYs. Compared to MIPOGG, the universal testing strategy was $1333 ($732; $1953) more costly and associated with 0.011 (-0.043; 0.064) additional QALYs. The ICUR for the MIPOGG strategy was $33,947/QALY when compared to the physician strategy; the ICUR for universal testing strategy was $118,631/QALY when compared to the MIPOGG strategy. DISCUSSION: This study provides evidence for clinical and policy decision-making on the cost-effectiveness of genetic referral strategies to identify LFS in the setting of osteosarcoma. MIPOGG-guided strategy was most likely to be cost-effective at a willingness-to-pay threshold value of $50,000/QALY.

Performance of the eHealth decision support tool, MIPOGG, for recognising children with Li-Fraumeni, DICER1, Constitutional mismatch repair deficiency and Gorlin syndromes.

BACKGROUND: Cancer predisposition syndromes (CPSs) are responsible for at least 10% of cancer diagnoses in children and adolescents, most of which are not clinically recognised prior to cancer diagnosis. A variety of clinical screening guidelines are used in healthcare settings to help clinicians detect patients who have a higher likelihood of having a CPS. The McGill Interactive Pediatric OncoGenetic Guidelines (MIPOGG) is an electronic health decision support tool that uses algorithms to help clinicians determine if a child/adolescent diagnosed with cancer should be referred to genetics for a CPS evaluation. METHODS: This study assessed MIPOGG's performance in identifying Li-Fraumeni, DICER1, Constitutional mismatch repair deficiency and Gorlin (nevoid basal cell carcinoma) syndromes in a retrospective series of 84 children diagnosed with cancer and one of these four CPSs in Canadian hospitals over an 18-year period. RESULTS: MIPOGG detected 82 of 83 (98.8%) evaluable patients with any one of these four genetic conditions and demonstrated an appropriate rationale for suggesting CPS evaluation. When compared with syndrome-specific clinical screening criteria, MIPOGG's ability to correctly identify children with any of the four CPSs was equivalent to, or outperformed, existing clinical criteria respective to each CPS. CONCLUSION: This study adds evidence that MIPOGG is an appropriate tool for CPS screening in clinical practice. MIPOGG's strength is that it starts with a specific cancer diagnosis and incorporates criteria relevant for associated CPSs, making MIPOGG a more universally accessible diagnostic adjunct that does not require in-depth knowledge of each CPS.

Thrombocytopenia and neonatal outcomes among extremely premature infants exposed to maternal hypertension.

BACKGROUND: Hypertensive disorders of pregnancy (HDP) are associated with neonatal hematological disturbances, such as thrombocytopenia. The association of HDP to platelet counts in the context of extreme prematurity, to trends of platelet counts during neonatal hospitalization, and to frequency of platelet transfusions remain to be explored. PROCEDURE: Retrospective study of infants born at less than 29 weeks born between 2015 and 2019. Platelet counts were collected on initial complete blood count, at 2 weeks, 32 weeks post-menstrual age (PMA), 36 weeks PMA, and closest to discharge. We examined the association between HDP and platelet counts at each time point, frequency of platelet transfusions and intraventricular hemorrhage (IVH) grade 3 or more. RESULTS: Total 296 infants were included, 43 exposed to HDP. Infants exposed had lower platelet counts at each time point, as well as a higher prevalence of platelet less than 150 × 109 /L on one of the time points (32% vs. 65%, p < .001). Infants exposed to maternal hypertension were more frequently exposed to platelet transfusions (63% vs. 18%, p < .001). Mixed effect model demonstrated an association between HDP and a lower trend in platelet counts at each time point (ß = -94 × 103 /µl, p < .001). Although initial platelet count was associated with severe IVH, it was not associated to exposure to HDP. CONCLUSION: Premature infants exposed to HDP have a higher prevalence of thrombocytopenia, increased frequency of platelet transfusion, and an altered trend in platelet counts during neonatal hospitalization.

A systematic review of the prevalence of pathogenic or likely pathogenic germline variants in individuals with FOXO1 fusion-positive rhabdomyosarcoma.

Several cancer predisposition syndromes (CPS) are reported to predispose to rhabdomyosarcoma, most frequently in children with embryonal rhabdomyosarcoma. There are lingering questions over the role of CPS in individuals with alveolar rhabdomyosarcoma (ARMS), which are frequently driven by FOXO1 fusion oncoproteins. We conducted a systematic review to identify patients with FOXO1 fusion-positive ARMS (FP-ARMS) who underwent germline DNA sequencing. We estimated the prevalence of pathogenic/likely pathogenic (P/LP) variants in cancer predisposing genes (CPGs) and of CPSs. We included 19 publications reporting on 191 patients with FP-ARMS. P/LP variants in CPGs were identified in 26/191 (13.6%) patients, nine (4.9%) of which were associated with a CPS diagnosis. Evidence for causal associations between CPSs and FP-ARMS could not be assessed with available data from this review. Only one patient was affected with a CPS known to predispose to rhabdomyosarcoma, Li-Fraumeni syndrome. Typical CPS associations with rhabdomyosarcoma are rare, but not nonexistent, in patients with FP-ARMS. FOXO1 fusion status, alone, is insufficient for clinicians to rely on to distinguish between patients with/without CPS.

Multicenter real-world experience of the clinical efficacy and tolerance of pazopanib in high-risk pediatric solid tumors (PazoPed).

Pazopanib, a receptor tyrosine kinase inhibitor, exhibits anti-tumor activity in adult bone and soft-tissue sarcomas (STS), but has not yet been approved for pediatric tumors. The primary objective was to evaluate pazopanib efficacy when used alone or in combination with topotecan. This real-world multicenter retrospective study included patients with solid tumors, aged 25 years or less at the time of initial diagnosis, treated with pazopanib outside of a clinical trial. Nineteen patients were eligible for efficacy analysis: 14 bone tumors and 5 STS. At pazopanib initiation, the median age was 16.9 years, 18 patients had metastatic disease with a median of 2 prior therapeutic lines. With 6.2 months of median follow-up, no objective response was observed, but 10 patients (52.6%) had stable disease at 8 weeks and the 6-month disease control rate was 26.3%. The median progression free (PFS) and overall survival (OS) were 3.0 months and 6.2 months, respectively. Multivariate analysis showed an inverse relationship between the number of prior treatment lines and PFS and OS (hazard ratio = 1.73 (p = 0.04) and 1.76 (p = 0.03), respectively). Our study showed a potential tumor control activity of pazopanib in pediatric bone and soft tissue sarcomas. Further studies are warranted to determine the optimal timing and condition for pazopanib introduction to maximize the effect.

An eHealth decision-support tool to prioritize referral practices for genetic evaluation of patients with Wilms tumor.

Over 10% of children with Wilms tumor (WT) have an underlying cancer predisposition syndrome (CPS). Cognizant of increasing demand for genetic evaluation and limited resources across health care settings, there is an urgent need to rationalize genetic referrals for this population. The McGill Interactive Pediatric OncoGenetic Guidelines study, a Canadian multi-institutional initiative, aims to develop an eHealth tool to assist physicians in identifying children at elevated risk of having a CPS. As part of this project, a decisional algorithm specific to WT consisting of five tumor-specific criteria (age <2 years, bilaterality/multifocality, stromal-predominant histology, nephrogenic rests, and overgrowth features) and universal criteria including features of family history suspicious for CPS and congenital anomalies, was developed. Application of the algorithm generates a binary recommendation-for or against genetic referral for CPS evaluation. To evaluate the algorithm's sensitivity for CPS identification, we retrospectively applied the tool in consecutive pediatric patients (n = 180) with WT, diagnosed and/or treated at The Hospital for Sick Children (1997-2016). Odds ratios were calculated to evaluate the strengths of associations between each criterion and specific CPS subtypes. Application of the algorithm identified 100% of children with WT and a confirmed CPS (n = 27). Age <2 years, bilaterality/multifocality, and congenital anomalies were strongly associated with pathogenic variants in WT1. Presence of >1 overgrowth feature was strongly associated with Beckwith-Wiedemann syndrome. Stromal-predominant histology did not contribute to CPS identification. We recommend the incorporation of the WT algorithm in the routine assessment of children with WT to facilitate prioritization of genetic referrals in a sustainable manner.

Paediatric ovarian tumours and their associated cancer susceptibility syndromes.

Non-epithelial ovarian tumours are rare neoplasms that occasionally arise in childhood and adolescence. They can be associated with various cancer susceptibility syndromes. The morphological overlap seen across these tumours and their rarity can make the diagnosis challenging. In the case of an incorrect diagnosis, the underlying genetic susceptibility may be missed. In this review, we outline the genetic background of ovarian non-epithelial tumours arising in children, emphasizing the genes harbouring pathogenic germline variants associated with each tumour type. Specifically, juvenile granulosa cell tumours, Sertoli-Leydig cell tumours, sex cord tumours with annular tubules, Sertoli cell tumours, germ cell tumours and small cell carcinoma of the ovary of hypercalcaemic type are discussed in this review. For each tumour type, we detail the personal and family history features and the presenting characteristics of the ovarian tumour as well as the pathological features and molecular markers that point towards a cancer predisposition syndrome. Throughout, we stress the need for specialised pathological review in difficult cases.

Retrospective evaluation of a decision-support algorithm (MIPOGG) for genetic referrals for children with neuroblastic tumors.

BACKGROUND: Neuroblastoma is the most common pediatric extracranial solid tumor. Germline pathogenic variants in ALK and PHOX2B, as well as other cancer predisposition genes, are increasingly implicated in the pathogenesis of neuroblastic tumors. A challenge for clinicians is the identification of children with neuroblastoma who require genetics evaluation for underlying cancer predisposition syndromes (CPS). PROCEDURE: We developed a decisional algorithm (MIPOGG) to identify which patients with neuroblastic tumors have an increased likelihood of an underlying CPS. This algorithm, comprising 11 Yes/No questions, evaluates features in the tumor, personal and family history that are suggestive of an underlying CPS. We assessed the algorithm's performance in a retrospective cohort. RESULTS: Two hundred and nine of 278 consecutive patients with neuroblastic tumors at The Hospital for Sick Children (2007-2016) had sufficient clinical data for retrospective application of the decisional algorithm. Fifty-one of 209 patients had been referred to genetics for CPS evaluation; 6/51 had a genetic or clinical confirmation of a CPS. The algorithm correctly identified all six children (Beckwith-Wiedemann (n = 2), Fanconi anemia, RB1, PHOX2B, chromosome duplication involving ALK) as requiring a genetic evaluation by using clinical features present at diagnosis. The level of agreement between the algorithm and physicians was 83.9%, with 15 more patients identified by the algorithm than by physicians as requiring a genetics referral. CONCLUSIONS: This decisional algorithm appropriately detected all patients who, following genetic evaluation, were confirmed to have a CPS and may improve the detection of CPS in patients with neuroblastic tumors compared with current practice.

Sequencing of DICER1 in sarcomas identifies biallelic somatic DICER1 mutations in an adult-onset embryonal rhabdomyosarcoma.

BACKGROUND: Sarcomas are rare and heterogeneous cancers. We assessed the contribution of DICER1 mutations to sarcoma development. METHODS: The coding region of DICER1 was sequenced in 67 sarcomas using a custom Fluidigm Access Array. The RNase III domains were Sanger sequenced in six additional sarcomas to identify hotspot DICER1 variants. RESULTS: The median age of sarcoma diagnosis was 45.7 years (range: 3 months to 87.4 years). A recurrent embryonal rhabdomyosarcoma (ERMS) of the broad ligament, first diagnosed at age 23 years, harboured biallelic pathogenic somatic DICER1 variants (1 truncating and 1 RNase IIIb missense). We identified nine other DICER1 variants. One somatic variant (p.L1070V) identified in a pleomorphic sarcoma and one germline variant (c.2257-7A>G) may be pathogenic, but the others are considered to be benign. CONCLUSIONS: We show that deleterious DICER1 mutations underlie the genetic basis of only a small fraction of sarcomas, in particular ERMS of the urogenital tract.

The McGill Interactive Pediatric OncoGenetic Guidelines: An approach to identifying pediatric oncology patients most likely to benefit from a genetic evaluation.

Identifying cancer predisposition syndromes in children with tumors is crucial, yet few clinical guidelines exist to identify children at high risk of having germline mutations. The McGill Interactive Pediatric OncoGenetic Guidelines project aims to create a validated pediatric guideline in the form of a smartphone/tablet application using algorithms to process clinical data and help determine whether to refer a child for genetic assessment. This paper discusses the initial stages of the project, focusing on its overall structure, the methodology underpinning the algorithms, and the upcoming algorithm validation process.

The influence of clinical and genetic factors on patient outcome in small cell carcinoma of the ovary, hypercalcemic type.

OBJECTIVE: Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is an aggressive tumor, with long term survival at ~30% in early stage disease. SCCOHT is caused by germline and somatic SMARCA4 mutations, but the effect of the mutation type on patients remains unknown. Furthermore, the rarity of SCCOHT has resulted in varied treatment, with no standardized protocols. We analyzed 293 cases to determine the effect of treatment modalities and SMARCA4 mutations on patient diagnosis and outcome. METHODS: In 293 SCCOHT patients we collected information on age and stage at diagnosis, treatment modality (surgery, chemotherapy, radiotherapy, and/or high-dose chemotherapy with autologous stem cell rescue (HDC-aSCR)), SMARCA4 mutation origin (germline/somatic), and overall survival. Cox analysis and log-rank tests were performed on 257 cases with available survival data. RESULTS: The strongest prognostic factors were stage at diagnosis (p=2.72e-15) and treatment modality (p=3.87e-13). For FIGO stages II-IV, 5-year survival was 71% for patients who received HDC-aSCR, compared to 25% in patients who received conventional chemotherapy alone following surgery (p=0.002). Patients aged ≥40 had a worse outcome than younger patients (p=0.04). Twenty-six of 60 tested patients carried a germline SMARCA4 mutation, including all patients diagnosed <15years; carriers presented at a younger age than non-carriers (p=0.02). CONCLUSIONS: Stage at diagnosis is the most significant prognostic factor in SCCOHT and consolidation with HDC-aSCR may provide the best opportunity for long-term survival. The large fraction of SMARCA4 germline mutations carriers warrants genetic counseling for all patients.

Evolution of Renal Cysts to Anaplastic Sarcoma of Kidney in a Child With DICER1 Syndrome.

Anaplastic sarcoma of kidney (ASK) is a rare neoplasm recently associated with DICER1 mutations. We report a child with germline DICER1 mutation who developed ASK in preexisting septated renal cysts, which were likely cystic nephroma. From age 2.5 to 6 years, sonographic imaging illustrated changes in the size and number of renal cysts, followed at age 8.8 years by a mass, pathologically an ASK. Lung cysts resected in infancy were diagnosed retrospectively as pleuropulmonary blastoma. Both tumors had acquired somatic DICER1 mutations. Ultrasonographic evolution of renal cysts to ASK has not previously been documented. Children with both pulmonary and renal cysts are candidates for DICER1 mutation testing.

Germline p.R181H variant in TP53 in a family exemplifying the genotype-phenotype correlations in Li-Fraumeni syndrome.

Li-Fraumeni syndrome (LFS) is a cancer predisposition syndrome associated with germline pathogenic/likely pathogenic variants in TP53. Genotype-phenotype correlations are progressively being characterized in LFS with certain TP53 variants associated with attenuated penetrance and phenotypes. We report on a family harboring a TP53 p.R181H variant presenting with a restricted cancer phenotype in adulthood. The proband was a female with breast cancer at the age of 71 years who had three first degree relatives also diagnosed with breast cancer after the age of 40 years (mother, two sisters). Of the nine individuals harboring the variant (6 genetically confirmed, 3 obligate heterozygous), six have not developed malignancies at this time (age range: 36-42). No childhood-onset cancers were reported in this family. A concomitant literature review identified 51 additional individuals harboring the p.R181H variant in TP53, presenting a tumor phenotype dominated by breast cancer. Rare occurrences of other adult-onset cancers (prostate, colorectal and thyroid) and only few childhood onset cancer were documented. These observations are consistent with functional analysis showing that p.R181H retains partial p53 function and suggesting possible reduced cancer penetrance, particularly in the pediatric setting.

Late-onset tumors in rhabdoid tumor predisposition syndrome type-1 (RTPS1) and implications for surveillance.

Rhabdoid tumor predisposition syndrome type-1 (RTPS1) is characterized by germline pathogenic variants in SMARCB1 and development of INI1-deficient rhabdoid tumors in early childhood. Due to its poor prognosis, the risk of subsequent tumor development and the impact of surveillance at later ages are poorly understood. We retrospectively reviewed individuals referred to the Cancer Genetics Program at The Hospital for Sick Children for SMARCB1 genetic testing and/or surveillance for RTPS1. In addition, to explore characteristics of late-onset tumors in RTPS1, a literature review was conducted. Of eighty-three individuals (55 probands and 28 family members), 12 probands and 4 family members were genetically confirmed with RTPS1. Four pediatric probands with RTPS1 underwent surveillance. An additional three individuals, including one patient with 22q11.2 distal deletion without history of tumor, one patient with negative genetic testing results but clinically diagnosed with RTPS1, and one sibling identified through cascade testing, underwent surveillance. Three patients with RTPS1 developed tumors between the ages of 9 and 17, including malignant rhabdoid tumors (N = 3), schwannomas (N = 4), and epithelioid malignant peripheral nerve sheath tumor (N = 1). Three of these lesions were asymptomatically detected by surveillance. A literature review revealed 17 individuals with RTPS1 who developed INI1-deficient tumors after age five. Individuals with RTPS1 remain at elevated risk for developing INI1-deficient tumors after the peak age of rhabdoid tumor in early childhood. Extension of surveillance beyond 5 years of age could lead to improved survival and reduced morbidity for these patients, and prospective evaluation of revised approaches will be important.

Access to innovative therapies in pediatric oncology: Report of the nationwide experience in Canada.

BACKGROUND: The need for new therapies to improve survival and outcomes in pediatric oncology along with the lack of approval and accessible clinical trials has led to "out-of-trial" use of innovative therapies. We conducted a retrospective analysis of requests for innovative anticancer therapy in Canadian pediatric oncology tertiary centers for patients less than 30 years old between 2013 and 2020. METHODS: Innovative therapies were defined as cancer-directed drugs used (a) off-label, (b) unlicensed drugs being used outside the context of a clinical trial, or (c) approved drugs with limited evidence in pediatrics. We excluded cytotoxic chemotherapy, cellular products, and cytokines. RESULTS: We retrieved data on 352 innovative therapy drug requests. Underlying diagnosis was primary CNS tumor 31%; extracranial solid tumor 37%, leukemia/lymphoma 22%, LCH 2%, and plexiform neurofibroma 6%. RAS/MAP kinase pathway inhibitors were the most frequently requested innovative therapies in 28% of all requests followed by multi-targeted tyrosine kinase inhibitors (17%), inhibitors of the PIK3CA-mTOR-AKT pathway (8%), immune checkpoints inhibitors (8%), and antibody drug conjugates (8%). In 112 out of 352 requests, innovative therapies were used in combination with another anticancer agent. 48% of requests were motivated by the presence of an actionable molecular target. Compassionate access accounted for 52% of all requests while public insurance was used in 27%. Mechanisms of funding varied between provinces. CONCLUSION: This real-world data collection illustrates an increasing use of "out-of-trial" innovative therapies in pediatric oncology. This new field of practice warrants further studies to understand the impact on patient trajectory and equity in access to innovative therapies.

Comparison of clinical selection-based genetic testing with phenotype-agnostic extensive germline sequencing to diagnose genetic predisposition in children with cancer: a prospective diagnostic study.

BACKGROUND: Germline data have become widely available in paediatric oncology since the introduction of paired tumour-germline sequencing. To guide best practice in cancer predisposition syndrome (CPS) diagnostics, we aimed to assess the diagnostic yield of extensive germline analysis compared with clinical selection-based genetic testing among all children with cancer. METHODS: In this prospective diagnostic study, all children (aged 0-19 years) with newly diagnosed neoplasms treated in the Netherlands national centre, the Princess Máxima Center for Pediatric Oncology (Utrecht, Netherlands), between June 1, 2020, and July 31, 2022, were offered two approaches to identify CPSs. In a phenotype-driven approach, paediatric oncologists used the McGill Interactive Pediatric OncoGenetic Guidelines tool to select children for referral to a clinical geneticist, and for genetic testing. In a phenotype-agnostic approach, CPS gene panel sequencing (143 genes) was offered to all children. In children declining the research CPS gene panel, 49 CPS genes were still analysed as part of routine diagnostics by the pathologist. Children with a causative CPS identified before neoplasm diagnosis were excluded. The primary objective was to compare the number and type of patients diagnosed with a CPS between the two approaches. FINDINGS: 1052 children were eligible for this study, of whom 733 (70%) completed both the phenotype-driven approach and received phenotype-agnostic CPS gene panel sequencing (143 genes n=600; 49 genes n=133). In 53 children, a CPS was identified: 14 (26%) were diagnosed by the phenotype-driven approach only, 22 (42%) by CPS gene sequencing only, and 17 (32%) by both approaches. In 27 (51%) of the 53 children, the identified CPS was considered causative for the child's neoplasm. Only one (4%) of the 27 causative CPSs was missed by the phenotype-driven approach and was identified solely by phenotype-agnostic CPS gene sequencing. In 26 (49%) children, a CPS with uncertain causality was identified, including 14 adult-onset CPSs. The CPSs with uncertain causality were mainly detected by the phenotype-agnostic approach (21 [81%] of 26). INTERPRETATION: Phenotype-driven genetic testing and phenotype-agnostic CPS gene panel sequencing were complementary. The phenotype-driven approach identified the most causative CPSs. CPS gene panel sequencing identified additional CPSs, many of those with uncertain causality, but some with clinical utility. We advise clinical evaluation for CPSs in all children with neoplasms. Phenotype-agnostic testing of all CPS genes is preferably conducted only in research settings and should be paired with counseling. FUNDING: Stichting Kinderen Kankervrij.

The clinical utility of integrative genomics in childhood cancer extends beyond targetable mutations.

We conducted integrative somatic-germline analyses by deeply sequencing 864 cancer-associated genes, complete genomes and transcriptomes for 300 mostly previously treated children and adolescents/young adults with cancer of poor prognosis or with rare tumors enrolled in the SickKids Cancer Sequencing (KiCS) program. Clinically actionable variants were identified in 56% of patients. Improved diagnostic accuracy led to modified management in a subset. Therapeutically targetable variants (54% of patients) were of unanticipated timing and type, with over 20% derived from the germline. Corroborating mutational signatures (SBS3/BRCAness) in patients with germline homologous recombination defects demonstrates the potential utility of PARP inhibitors. Mutational burden was significantly elevated in 9% of patients. Sequential sampling identified changes in therapeutically targetable drivers in over one-third of patients, suggesting benefit from rebiopsy for genomic analysis at the time of relapse. Comprehensive cancer genomic profiling is useful at multiple points in the care trajectory for children and adolescents/young adults with cancer, supporting its integration into early clinical management.

Von Hippel-Lindau disease and rapidly progressing pheochromocytomas in siblings.

Von Hippel-Lindau (VHL) disease is an autosomal dominant inherited condition with a predisposition to the development of a variety of tumors including pheochromocytomas. A number of cancer surveillance protocols for patients with VHL have been developed, all of which are based on expert opinion. We report a case of two brothers with a strong family history of VHL type 2 due to a pathogenic germline VHL variant, specifically, a surface missense substitution, with a rapidly progressive clinical course that both presented with a large adrenal mass. Both brothers presented with large pheochromocytomas, the earliest presentation being at age 7, despite routine screening. The rapid progression and early presentation of these patients raises an important discussion around the commonly used surveillance protocols for pheochromocytoma in pediatric patients with VHL and missense mutations. We conclude that a more accelerated surveillance protocol may be adequate for VHL families with a high pheochromocytoma risk.

Medulloblastoma and Cowden syndrome: Further evidence of an association.

Cowden syndrome (CS) is an autosomal dominant hamartoma and tumor predisposition syndrome caused by heterozygous pathogenic germline variants in PTEN in most affected individuals. Major features include macrocrania, multiple facial tricholemmomas, acral and oral keratoses and papillomas, as well as mammary, non-medullary thyroid, renal, and endometrial carcinomas. Lhermitte-Duclos disease (LDD), or dysplastic gangliocytoma of the cerebellum, is the typical brain tumor associated with CS; the lifetime risk for LDD in CS patients has been estimated to be as high as 30%. In contrast, medulloblastoma is much rarer in CS, with only 4 reported cases in the literature. We report a 5th such patient. All 5 patients were diagnosed between 1 and 2 years of age and not all showed the pathognomonic clinical stigmata of CS at the time of their medulloblastoma diagnosis. Where detailed information was available, the medulloblastoma was of the SHH-subtype, in keeping with the observation that in sporadic medulloblastomas, PTEN-alterations are usually encountered in the SHH-subtype. Medulloblastomas can be associated with several tumor-predisposition syndromes and of the 4 medulloblastoma subtypes, SHH-medulloblastomas in children have the highest prevalence of predisposing germline variants (approx. 40%). CS should be added to the list of SHH-medulloblastoma-associated syndromes. Germline analysis of PTEN should be performed in infants with SHH-medulloblastomas, regardless of their clinical phenotype, especially if they do not carry pathogenic germline variants in PTEN or PTEN, the most commonly altered predisposing genes in this age-group. In addition, these cases show that CS has a biphasic brain tumor distribution, both in regards to the age of onset and the tumor type: a small number of CS patients develop a medulloblastoma in infancy while many more develop LDD in adulthood.