SUFU Mutations Research Articles

Clinicopathological and molecular spectrum of patients with germline SUFU mutations: A case series.

One of the hereditary syndromes associated with multiple early-onset basal cell carcinomas (BCCs) is basal cell nevus syndrome (BCNS), of which a minority is caused by germline SUFU mutations. Germline SUFU mutations show a spectrum of phenotypes, of which multiple hereditary infundibulocystic basal cell carcinoma syndrome (MHIBCC) is one. Patients with MHIBCC develop multiple basaloid skin tumors from middle age onwards. Three patients presenting with an MHIBCC phenotype were tested for a germline SUFU mutation. Skin biopsies were assessed by two dermatopathologists. Our study adds three new pathogenic SUFU variants, including a mosaic, to the current literature. Literature suggests a spectrum of phenotypes of patients carrying the same SUFU mutation, which ranges from the MHIBCC phenotype, to BCNS, to patients that develop life-threatening brain tumors. This last risk is significantly higher in germline SUFU mutation carriers when compared to BCNS patients carrying germline PTCH1 mutations. Germline SUFU mutation carriers should be recognized as a distinct group of patients carrying specific health risks, independent of meeting the BCNS criteria. Phenotypic prediction based on the specific SUFU mutation seems unfeasible. It is of utmost importance that the less apparent MHIBCC phenotype is recognized, to provide (second generation) germline SUFU mutation carriers appropriate healthcare.

Mosaic SUFU mutation associated with a mild phenotype of multiple hereditary infundibulocystic basal cell carcinoma syndrome.

Multiple hereditary infundibulocystic basal cell carcinoma syndrome (MHIBCC), an autosomal dominant disorder caused by variants in SUFU, is characterized by numerous infundibulocystic basal cell carcinomas (IBCCs). In this report, we present a possible case of mosaic MHIBCC. A 57-year-old woman underwent the removal of four papules on her face, which were diagnosed as IBCCs. Exome sequencing revealed a SUFU c.1022+1G>A mutation within the skin tumor. The same mutation was detected in her blood but at a lower allele frequency. TA cloning revealed that the allele frequency of the mutation in the blood was 0.07. Additionally, tumor assessment revealed loss of heterozygosity (LOH) in chromosome 10, including the SUFU locus. These results indicate the patient had mosaicism for the SUFU mutation in normal tissues, aligning with the mosaic MHIBCC diagnosis. This, combined with LOH, likely contributed to IBCC development. Mosaic MHIBCC may present with milder symptoms. However, it may still increase the risk of developing brain tumors and more aggressive basal cell carcinoma. The possibility of mosaicism should be investigated in mild MHIBCC cases, where standard genetic tests fail to detect SUFU germline variants.

MDB-75. MOLECULAR PATHOLOGY, TREATMENT AND PROGNOSIS OF INFANT SONIC HEDGEHOG MEDULLOBLASTOMA: A GLOBAL MULTI-COHORT STUDY

Abstract BACKGROUND Clinical studies in infant medulloblastoma (iMB; <5 years) have, to date, focussed on modestly-sized or national trials cohorts and have not directly compared therapeutic approaches or placed these in the context of dedicated biomarker studies, to inform future treatment strategies. METHODS We assembled a multi-national cohort of molecularly and clinically-annotated iMBs (<5 years at diagnosis; n=646), the largest to date. We investigated molecular pathology, treatments received, and relationships to outcome within this population. RESULTS The SHH group (iMBSHH; n=267, 40%) predominated, encompassing SHH-1 (37.7%, median age 2.0 years), SHH-2 (47.0%, 1.4 years) and SHH-3 (14.4%, 3.0 years) WHO subgroups. MBEN histology was significantly enriched in SHH-2, and SUFU mutation and MYCN amplification in SHH-1 and SHH-3, respectively. Notably, TP53 mutations were identified in all subgroups; in SHH-1 and SHH-2 (each n=3) tumours lacked features typically associated with TP53-mutated SHH-3 (LCA histology and MYCN amplification) and did not have a worse survival. Upfront radiation-sparing treatments were used in 132/267 children and comprised regimens founded on intraventricular methotrexate (IVT-MTX; 54.5%), high-dose (HDCTx; 22.0%) or standard-dose (23.5%) chemotherapy. Across all radio-naive iMBSHH, non-DN/MBEN histology (HR 2.76, CI 1.26-6.01, p=0.011) and SHH-1 (vs SHH-2, HR 2.51, CI 1.25-5.01, p=0.009) conferred worse PFS in univariable analysis; subgroup was the only independently prognostic risk-factor (multivariable analysis; SHH-1 HR 2.65, CI 1.27-5.51, p=0.009). 5-year OS for HDCTx recipients was very favourable in SHH-1 (100%) and SHH-2 (93.3%), and subgroup-dependent for IVT-MTX (SHH-1; 76.4%, SHH-2; 100%, p=0.009). In CSI-treated iMBSHH (n=49), non-DN/MBEN histology (HR 10.23, CI 2.22-47.04, p=0.003) and MYCN amplification (HR 7.35, CI 2.01-26.87, p=0.003) conferred worse PFS. CONCLUSION iMBSHH outcomes in this cohort are dependent upon WHO subgroup, histology and therapy received. These findings provide an evidence-based foundation for selection of cohorts and therapies for prospective assessment in forthcoming iMBSHH clinical trials (e.g. SIOP-CONNECT-YC-MB-LR).

MDB-110. A NOVEL TRANSGENIC MOUSE MODEL FOR GLI2-AMPLIFIED MEDULLOBLASTOMA

Abstract BACKGROUND Medulloblastoma (MB) is one of the most common malignant childhood brain tumors. The sonic hedgehog (SHH) subgroup represents 30% of MBs and can arise from granule neuron progenitors (GNPs). SHH-MB is a diverse subgroup of tumors which often exhibit loss-of function mutations in PTCH1 or SUFU, activating mutations in the receptor SMO and amplification of the transcription factor GLI2. Of note, SHH-MBs harboring GLI2-amplification and associated with P53 mutations have extremely poor prognosis with a 5-year survival rate less than 30%. These tumors are non-responsive to SMO inhibitors, which are the only targeted treatment currently available for SHH-MB. Therefore, the development of novel effective therapies for this disease is urgent. Although GLI2 amplification is detected in SHH-MBs, it is not yet known if GLI2 can drive oncogenic activity in this disease. METHOD To elucidate the mechanisms underlying tumorigenesis, our group has developed a novel transgenic model of GLI2-driven MB by expressing a constitutively active form of GLI2 (GLI2A) in Atoh1+ cells in the developing mouse cerebellum to form tumors. To accomplish this, we crossed R26;Gli2A mice with Atoh1-Cre. RESULTS The resulting tumors faithfully recapitulate human GLI2-amplified MB at the cellular and molecular levels. Inactivation of GLI2A resulted in tumor regression, indicating that GLI2 is not only critical for tumorigenesis, but also required for tumor maintenance, suggesting that targeting GLI2 itself or its downstream targets may be effective to inhibit growth of GLI2-driven MB. Interestingly, activation of GLI2A expression in the neonatal cerebellum was not sufficient to drive tumorigenesis, indicating that GLI2-driven MB arises from more primitive cells in the developing cerebellum. CONCLUSION Taken together, our studies demonstrate for the first time the role of GLI2 as an oncogenic driver of MB and introduce a novel mouse model which can be used to develop targeted therapies for this disease.

MDB-24. SHH MEDULLOBLASTOMA WITH SMO MUTATION BEFORE THE AGE OF 5YEARS OLD

Abstract BACKGROUND SHH medulloblastomas represent around 30% of MB’s and occur mostly in infants and adults with an intermediate prognosis. The driving mutations concern mostly PTCH1(43%), SUFU(10%) or SMO(9%). SMO activating mutations have been described almost exclusively in adults, and is extremely rare in infants. The features and outcome of SMO mutated infant MB are not known so far. PATIENTS AND METHODS We did a national retrospective analysis of children under 5 years with a SHH medulloblastoma and a somatic SMO mutation. We collected clinical, radiological and biological data (centralised reviews) with addition of methyloma, aiming to depict the clinico-molecular features and the outcome of these rare MB. RESULTS We identified 6 patients from 2014 to 2020. The median age at diagnosis was 3.2years. No evidence of metastatic disease was found for 5/6 patients and one had a positive CSF cytology. All patients underwent a complete removal. All had an extensive nodularity histologic subtype, no specific alterations in CGH apart from gains of all chromosomes 2,7 and,15. Methyloma classified 4/6 in subgroup SHH-1 and 2 in subgroup SHH-2. One patient had a second cerebellar lesion with a different radiological aspect; histological analysis and methylation profiling revealed a subependymoma, sharing the same SMO mutation than the MB ((c.1604G>T/p.(Trp535Leu)), suggesting a mosaicism. Another patient presented a polymalformative disorder diagnosed as a Curry-Jones syndrome, in agreement with the finding of mosaic SMO variant (c.1234C>T(p.Leu412Phe)). All patients received several cycles of chemotherapy, and no radiotherapy. With a median follow-up of 3.9 years, all patients were alive in complete remission with no relapse. CONCLUSION This data suggests that an underlying mosaicism must be sought in these very rare patients, and that the outcome seems overall similar to other infants with SHH medulloblastoma and more classical SUFU or PTCH1 mutations.

SURG-37. ONCOGENIC MUTATIONS AND TUMOR CHARACTERISTICS IN OLFACTORY GROOVE MENINGIOMAS: IMPLICATIONS FOR PERSONALIZED TREATMENT STRATEGIES

Abstract OBJECTIVE To investigate the correlation between clinical and radiologic features of olfactory groove meningiomas (OGM) and their tumor molecular profiles, focusing on oncogenic mutations identified through genomic studies. METHODS Targeted next-generation sequencing analyses were conducted on 54 patients with OGM (37 females and 17 males) to determine the frequency of SMO, AKT1, PIK3CA, and other mutations. The molecular results were then correlated with clinical and radiographic tumor features. RESULTS Among the OGM patients, SMO mutations were found in 16 (29.6%) cases, AKT1 mutations in 13 (24.1%), and PIK3CA/PIK3R1 mutations in 9 (16.7%) cases. Less common mutations in POLR2A, SUFU, and NF1 were observed in 8 (14.8%) cases, while 8 OGM (14.8%) did not have identifiable driver mutations (Wild-type group, WT). The median age at first diagnosis was 64.1 years (25-87 years), with the youngest group represented by PIK3CA-mutant patients at 52 years (49-78 years). The sex distribution was similar across the SMO-, AKT1- and PIK3CA-mutant groups (F:M = 2.1:1). OGM with SMO mutations exhibited larger tumor volumes (329.4 ± 323.0 cm3) compared to AKT1-mutant tumors (283.3 ± 156.2 cm3). Tumor infiltration of the ethmoid cells was found in 10 cases (22.2%), with the highest rate observed in PIK3CA-mutant OGM (40%), followed by 25% in SMO-mutant OGM. Tumor-associated hyperostosis of the sphenoid planum was common in OGM (72.2%), with the highest rate in the SMO group (75.0%) and the lowest rate in the AKT1-mutant group (30.8%). The majority of cases (n = 45, 83.3%) were classified as WHO grade 1 meningioma, while the remaining nine cases were WHO grade 2 (n = 8) and 3 (n = 1). CONCLUSIONS Overall, our data demonstrate the presence of clinically actionable mutations in the majority of olfactory groove meningiomas, and suggest a correlation between molecular status and common clinical and radiologic tumor features.

Basal cell nevus syndrome: the interface between dentistry and dermatology

Basal cell nevus syndrome is a rare, autosomal dominant disorder, predominantly caused by a mutation in the PTCH1 gene. As basal cell carcinomas and keratocysts are the most common abnormalities, dermatologists, orofacial maxillary surgeons, and dentists play a key role in patient care. From the age of 8, screening for odontogenic keratocysts with an orthopantomogram or MRI is recommended every other year. The intensity increases to annual screening after the development of the first odontogenic keratocyst. If BCNS is caused by an underlying SUFU mutation, screening is not indicated since there are no reports of odontogenic keratocyst in these patients to date. Radiation exposure by, for example, computed tomography, should be minimized as it induces new BCCs. Regular follow-up by a dermatologist for early diagnosis and treatment of (multiple) BCC's is recommended for life.

SUFU-associated Gorlin syndrome: Expanding the spectrum between classic nevoid basal cell carcinoma syndrome and multiple hereditary infundibulocystic basal cell carcinoma.

Basal cell nevus syndrome (BCNS), also known as Gorlin syndrome, is characterized by an aberrant activation of the hedgehog (Hh) pathway, most cases being caused by PTCH1 mutations. However, certain features such as multiple hereditary infundibulocystic basal cell carcinomas (MHIBCC), sclerotic fibromas, childhood medulloblastoma or meningioma may be relatively specific to a SUFU mutation. We present two patients with MHIBCC, along with a more complex cutaneous and extracutaneous phenotype. MHIBCC syndrome and BCNS may share clinical features and, indeed, both syndromes probably represent different degrees of upregulation in the Hh pathway.

PATH-32. CONCORDANCE FOR CDKN2A/B LOSS AND TERT MUTATION IN WHO 2021 CLASSIFICATION GRADE 3 MENINGIOMAS: A RETROSPECTIVE STUDY

Abstract BACKGROUND The new WHO 2021 classification included CDKN2A/B loss and TERT mutation as new criteria for Grade 3 meningiomas, but excluded H3K27me3 loss. Malignant behavior may be influenced by DNA methyltransferases (DNMT3A). SUFU mutations may carry a predisposition for multiple meningiomas. METHODS In this retrospective study, 228 patients with Grade 2, Grade 3 or recurrent Grade 1 meningiomas with resections from 1990 to July 2021 at Columbia University Medical Center were assessed for recurrence, histologic features, and molecular alterations. RESULTS Of 228 patients with meningiomas, 9 were recurrent Grade 1, 9 were Grade 1 transformed to Grade 2, 109 were non-recurrent Grade 2, 77 were recurrent Grade 2, 13 were transformed Grade 2 to Grade 3, and 5 were non-recurrent Grade 3 and 6 were recurrent Grade 3. Median follow-up was 42.0 months. Of the recurrent/transformed tumors, 89 were radiation-resistant. Average mitotic counts for non-recurrent Grade 2 vs. recurrent/transformed Grade 2 and non-recurrent Grade 3 vs. recurrent Grade 3 meningiomas were 4 vs. 5, 24 vs. 27 mitoses/10HPF, respectively. Of 36 meningiomas evaluated with NGS, the most common alterations was NF2 (20/36). CDKN2A/B was lost in 5 meningiomas, three with Grade 2 that transformed to Grade 3 and two with recurrent disease. TERT was mutant in 3/36, 2 of which were Grade 2 that transformed to Grade 3 meningiomas. H3K27M me3 was tested by IHC in 4 patients, 3 with retained staining, all of whom did not recur and 1 with loss of staining in a Grade 1 transformed to Grade 2. DNMT3A was found in 2 tumors, both radiation-induced. SUFU occurred in 3/16, one of each grade, all solitary. CONCLUSION In our limited cohort, we observed concordance with the new WHO 2021 criteria for Grade 3 meningiomas

MEDB-57.GNAS inactivation as a driver for sonic hedgehog-activated medulloblastoma

INTRODUCTION: Sonic hedgehog (SHH)-activated medulloblastoma is one of the four consensus molecular subgroups of medulloblastoma and is typically associated with PTCH1, SUFU, and/or SMO mutations. GNAS inactivating mutations are a less commonly recognized tumorigenic driver for SHH pathway activation. CASE PRESENTATION: We report the case of an 11-month-old male who presented with a large posterior fossa mass, cerebellar tonsillar herniation, and obstructive hydrocephalus. Following a successful gross total resection, pathology was consistent with desmoplastic/nodular medulloblastoma. Tumor molecular profiling using a DNA-based, next-generation sequencing platform detected a pathogenic frameshift mutation in the GNAS gene (p.D189Mfs*14, NM_000516.4:c.565_568del) at a variant allele frequency of 81%, suggestive of biallelic GNAS inactivation. The same mutation was detected from a buccal swab sample, confirming germline GNAS inactivation. Whole genome methylation profiling was consistent with medulloblastoma subclass SHH B (infant). Concurrent with this brain tumor evaluation, a skin biopsy was performed of scattered subcutaneous, plate-like nodules distributed over the patient’s back and extremities. This revealed metaplastic-appearing cancellous bone within the dermis and subcutaneous tissue consistent with plate-like osteoma cutis. He was treated with high-dose chemotherapy followed by autologous stem cell rescue and remains disease-free 15 months from diagnosis. DISCUSSION: There have been scattered case reports describing germline loss-of-function GNAS mutations acting as tumorigenic drivers of SHH medulloblastoma. However, GNAS alterations are not covered by most standard diagnostic molecular sequencing panels for medulloblastoma. Other phenotypic manifestations of germline inactivating GNAS mutations include pseudohypoparathyroidism, pseudopseudohypoparathyroidism, progressive osseous heteroplasia, and osteoma cutis. CONCLUSION: Knowledge of the possible association between germline GNAS inactivating mutations and the development of childhood SHH-activated medulloblastoma is essential for prompt diagnosis and treatment initiation. As such, consideration should be given for inclusion of GNAS alterations in diagnostic medulloblastoma sequencing panels, especially in the setting of osteoma cutis or other endocrinopathies.

MEDB-48. Infant medulloblastoma - SHH subtype – with residual disease. To treat or not to treat

Management of infant medulloblastoma remains a challenge. Front-line chemotherapy can successfully avoid radiation in low-risk infant medulloblastoma. Patients that do relapse can be salvaged long-term with radiotherapy. We report 4 cases of infants with medulloblastoma treated with chemotherapy (HIT2000 protocol) with residual or progressive disease. RESULTS: Four cases of infant medulloblastoma, all MBEN/nodular desmoplastic SHH type B, p53 WT, no MYC / MYCN amplification. CASE 1: 16 month old girl, metastatic lesions in the cerebellum and meningeal enhancement. Germline SUFU mutation. After 3 cycles of chemotherapy MRI showed more enhancement of the residual disease. To inform management, second look surgery was performed. Pathology showed fibrous tissue only, no malignant cells. The child continues to be treated as per HIT2000. CASE 2: 5 month old girl, metastatic lesions in the cerebellum. Germline SUFU mutation. 2 months after end of treatment, MRI demonstrated progression of cerebellar lesion. Surgical resection was performed, pathology showed differentiated mature neuronal tissue. No further treatment; remains in remission 1 year after suspected progression. CASE 3: 27 month old boy, metastatic lesions in cerebellum. Germline SUFU mutation. 1 month post-completion of treatment progressive prominent nodules along the cerebellum and cerebellar leptomeningeal enhancement. Biopsy not feasible so close MRI surveillance was initiated. MRI remains stable 1 year after suspected progression. CASE 4: 30 months old boy, non-metastatic disease. Complete resection. No germline mutation. End-of-treatment MRI showed subtle new intraspinal leptomeningeal deposits and a suspicious left optic tract nodule, subsequent MRI 8 weeks later showed clear progressive disease. Unfortunately, the child died before radiotherapy could be delivered. CONCLUSION: Salvage radiotherapy for infants with medulloblastoma who progress following chemotherapy treatment can be life-saving but risk significant cognitive impairment. Differentiation of medulloblastoma following radio/chemotherapy has been reported. We recommend considering tissue confirmation prior to embarking on further treatment for suspected relapse.

The developmental stage of the medulloblastoma cell-of-origin restricts Sonic hedgehog pathway usage and drug sensitivity.

ABSTRACTSonic hedgehog (SHH) medulloblastoma originates from the cerebellar granule neuron progenitor (CGNP) lineage, which depends on Hedgehog signaling for its perinatal expansion. Whereas SHH tumors exhibit overall deregulation of this pathway, they also show patient age-specific aberrations. To investigate whether the developmental stage of the CGNP can account for these age-specific lesions, we analyzed developing murine CGNP transcriptomes and observed highly dynamic gene expression as a function of age. Cross-species comparison with human SHH medulloblastoma showed partial maintenance of these expression patterns, and highlighted low primary cilium expression as hallmark of infant medulloblastoma and early embryonic CGNPs. This coincided with reduced responsiveness to upstream SHH pathway component Smoothened, whereas sensitivity to downstream components SUFU and GLI family proteins was retained. Together, these findings can explain the preference for SUFU mutations in infant medulloblastoma and suggest that drugs targeting the downstream SHH pathway will be most appropriate for infant patients.

Need for preventive diagnostics in patients with family history of Gorlin-Goltz syndrome (GGS)

BackgroundGorlin-Goltz syndrome is a disease develops as a result of genes PTCH1, PTCH2 or SUFU mutations which increases the risk of neoplasms. Craniofacial anomalies constitute the majority of the typical features of the disease. CaseThe authors describe the case of a 68-year-old patient referred for the extraction of tooth 48. Clinical examinations and radiological tests revealed changes suggestive of GGS. History taking revealed that the patient's child had been treated for the same syndrome for 20 years. PurposeThe goal of the study is to prove the importance of genetic testing which the family of the patient affected by GGS needs to undergo as soon as possible. ResultsGenetic tests performed in the patient exhibited the pathogenic variant in 1 allele of the PTCH1 gene, which confirmed the diagnosis of GGS. ConclusionsGenetic testing of the patient's family enables to avoid radical surgical intervention.

Prognostic impact of genetic alterations and methylation classes in meningioma.

Meningiomas are classified based on histological features, but genetic and epigenetic features are emerging as relevant biomarkers for outcome prediction and may supplement histomorphological evaluation. We investigated meningioma‐relevant mutations and their correlation with DNA methylation clusters and patient survival times. Formalin‐fixed and paraffin‐embedded samples of 126 meningioma patients (WHO grade I 52/126; 41.3%; WHO grade II: 48/126; 38.1%; WHO grade III: 26/126; 20.6%) were investigated. We analyzed NF2, TRAF7, KLF4, ARID, SMO, AKT, TERT promotor, PIK3CA, and SUFU mutations using panel sequencing and correlated them to DNA methylation classes (MC) determined using 850k EPIC arrays. The TRAKL mutation genotype was characterized by the presence of any of the following mutations: TRAF7, AKT1, and KLF4. Survival data including progression‐free survival (PFS) and overall survival (OS) was retrieved from chart review. Mutations were evident in 90/126 (71.4%) specimens with mutations in NF2 (39/126; 31.0%), TRAF7 (39/126; 31.0%) and KLF4 (25/126; 19.8%) being the most frequent ones. Two or more mutations were observed in 35/126 (27.8%) specimens. While TRAKL was predominantly found in benign MC, NF2 was associated with malign MC (p < 0.05). TRAF7, KLF4, and TRAKL mutation genotype were associated with improved PFS and OS (p < 0.05). TERT promotor methylation, intermediate, and malign MC were associated with impaired PFS and OS (p < 0.05). Methylation cluster showed better prognostic discrimination for PFS and OS (c‐index 0.77/0.75) than each of the individual mutations (c‐index 0.63/0.68). In multivariate analysis correcting for age, gender, MC, and WHO grade, none of the individual mutations except TERT remained an independent significant prognostic factor for PFS. Molecular profiling including mutational analysis and DNA methylation classification may facilitate more precise prognostic assessment and identification of potential targets for personalized therapy in meningioma patients.

Defining the Spectrum, Treatment and Outcome of Patients With Genetically Confirmed Gorlin Syndrome From the HIT-MED Cohort.

Gorlin syndrome is a genetic condition associated with the occurrence of SHH activated medulloblastoma, basal cell carcinoma, macrocephaly and other congenital anomalies. It is caused by heterozygous pathogenic variants in PTCH1 or SUFU. In this study we included 16 patients from the HIT2000, HIT2000interim, I-HIT-MED, observation registry and older registries such as HIT-SKK87, HIT-SKK92 (1987 – 2020) with genetically confirmed Gorlin syndrome, harboring 10 PTCH1 and 6 SUFU mutations. Nine patients presented with desmoplastic medulloblastomas (DMB), 6 with medulloblastomas with extensive nodularity (MBEN) and one patient with classic medulloblastoma (CMB); all tumors affected the cerebellum, vermis or the fourth ventricle. SHH activation was present in all investigated tumors (14/16); DNA methylation analysis (when available) classified 3 tumors as iSHH-I and 4 tumors as iSHH-II. Age at diagnosis ranged from 0.65 to 3.41 years. All but one patient received chemotherapy according to the HIT-SKK protocol. Ten patients were in complete remission after completion of primary therapy; four subsequently presented with PD. No patient received radiotherapy during initial treatment. Five patients acquired additional neoplasms, namely basal cell carcinomas, odontogenic tumors, ovarian fibromas and meningioma. Developmental delay was documented in 5/16 patients. Overall survival (OS) and progression-free survival (PFS) between patients with PTCH1 or SUFU mutations did not differ statistically (10y-OS 90% vs. 100%, p=0.414; 5y-PFS 88.9% ± 10.5% vs. 41.7% ± 22.2%, p=0.139). Comparing the Gorlin patients to all young, SHH activated MBs in the registries (10y-OS 93.3% ± 6.4% vs. 92.5% ± 3.3%, p=0.738; 10y-PFS 64.9%+-16.7% vs. 83.8%+-4.5%, p=0.228) as well as comparing Gorlin M0 SKK-treated patients to all young, SHH activated, M0, SKK-treated MBs in the HIT-MED database did not reveal significantly different clinical outcomes (10y-OS 88.9% ± 10.5% vs. 88% ± 4%, p=0.812; 5y-PFS 87.5% ± 11.7% vs. 77.7% ± 5.1%, p=0.746). Gorlin syndrome should be considered in young children with SHH activated medulloblastoma, especially DMB and MBEN but cannot be ruled out for CMB. Survival did not differ to patients with SHH-activated medulloblastoma with unknown germline status or between PTCH1 and SUFU mutated patients. Additional neoplasms, especially basal cell carcinomas, need to be expected and screened for. Genetic counselling should be provided for families with young medulloblastoma patients with SHH activation.

A novel anthelminthic drug suppresses the growth of medulloblastoma tumors by inhibiting PKA/Gli1 signaling axis

Pediatric brain tumor is one of the most malignant solid tumors in children and have profound impact on the morbidity and mortality in these patients. Statistically, brain tumors are one of the leading cause of cancer-related deaths in patients from 0-19 years of age. Medulloblastoma (MB) is one of the most common pediatric brain tumors occurring in children. Sonic hedgehog (Shh) activated subgroup of MB is considered to be highly aggressive and metastatic in nature. Shh-MB is characterized by mutations in PTCH1, SMO and SuFu along with amplified activation of Gli1, a major transcription factor of this signaling pathway. In the current study, we have evaluated the anti-cancer effects of an anthelminthic drug ‘moxidectin’. Several MB cell lines such as Daoy, UW426, UW228, ONS76, and PFSK1 were treated with moxidectin in a concentration and time dependent manner. Our results demonstrated that moxidectin treatment resulted in significantly reduced proliferation of MB cells. The IC50 of moxidectin in all the MB cell lines ranged 10-17μM after 24, 48 and 72 hours of treatment. Moreover, moxidectin was able to induce 3-4 fold increase of apoptosis in all the MB cell lines as evaluated by AnnexinV-FITC/PI assay, and increased cleavage of caspase 3 and PARP. Western blotting analysis demonstrated that moxidectin treatment significantly reduced non-canonical activation of Gli1 and its downstream effector molecules such as Pax-6, Oct-4, Sox-2 and Nanog. To our knowledge, this study for the first time focuses on GABAA receptor agonist mediated PKA inhibition and ultimately suppression of non-canonical Gli1 activation. Efficacy of moxidectin was evaluated in an in vivo tumor model by subcutaneously and intracranically implanting human Daoy MB cells. Our results demonstrated that 2.5 mg/kg moxidectin by oral administration everyday suppressed the growth of Daoy tumors by 50-55% in both subcutaneous and intracranial tumor models. Conclusively, our results indicate that moxidectin effectively reduces the growth of MB tumors by inhibiting PKA/Gli1 signaling. Most importantly, moxidectin is FDA approved drug and is already in clinical use for the treatment of river blindness in humans with an established safety record, therefore any positive findings from our studies will prompt further clinical investigation into repositioning moxidectin for the treatment of MB patients.

Differences in RNA and microRNA Expression Between PTCH1- and SUFU-mutated Medulloblastoma.

Germline mutations in PTCH1 or SUFU in the sonic hedgehog (SHH) pathway cause Gorlin's syndrome with increased risk of developing SHH-subgroup medulloblastoma. Gorlin's syndrome precludes the use of radiotherapy (a standard component of treatment) due to the development of multiple basal cell carcinomas. Also, current SHH inhibitors are ineffective against SUFU-mutated medulloblastoma, as they inhibit upstream genes. In this study, we aimed to detect differences in the expression of genes and microRNAs between SUFU- and PTCH1-mutated SHH medulloblastomas which may hint at new treatment directions. We sequenced RNA and microRNA from tumors of two patients with germline Gorlin's syndrome - one having PTCH1 mutation and one with SUFU mutation - followed by bioinformatics analysis to detect changes in genes and miRNAs expression in these two tumors. Expression changes were validated using qRT-PCR. Ingenuity pathway analysis was performed in search for targetable pathways. Compared to the PTCH1 tumor, the SUFU tumor demonstrated lower expression of miR-301a-3p and miR-181c-5p, matrix metallopeptidase 11 (MMP11) and OTX2, higher expression of miR-7-5p and corresponding lower expression of its targeted gene, connexin 30 (GJB6). We propose mechanisms to explain the phenotypic differences between the two types of tumors, and understand why PTCH1 and SUFU tumors tend to relapse locally (rather than metastatically as in other medulloblastoma subgroups). Our results help towards finding new treatable molecular targets for these types of medulloblastomas.

RARE-21. CANCER SPECTRUM IN GERMLINE SUFU MUTATION CARRIERS: A COLLABORATIVE PROJECT OF THE SIOPE HOST GENOME WORKING GROUP

BACKGROUNDLittle is known about cancer risk associated with pathogenic germline SUFU variants.METHODSData of all previously published and 25 still unpublished patients with a pathogenic germline SUFU mutation were compiled.RESULTS124 patients in 67 families were identified, most of them ascertained after the occurrence of a medulloblastoma (MB) or as part of Gorlin syndrome cohorts. Overall, 30 patients were healthy carriers and 94 patients developed a total of 129 tumors (up to 4 tumors/patient): 68 MBs, always as first tumor (median age at diagnosis: 1.5yr [0.1–5]), 22 patients with at least 1 basal cell carcinoma (BCC) (median 10/patient) (median age at first BCC: 43yr, [17–52]), 15 meningiomas (median age 43yr, [13–72]), 7 ovarian stromal/fibrous tumors (median age 12yr [5–34]), and 17 other tumors including 5 sarcomas (median age: 50yr [7–79]). Median age at last follow-up was 30yr. Nineteen patients died, including 11 from MB. Second malignancies were diagnosed in 21 patients including 13 in MB survivors. Mutations were inherited in 58/66 (88%) of cases in which inheritance could be tested and de novo in 8. In 6/67 families (9%), >2 children were diagnosed with a MB.CONCLUSIONIn this large cohort of germline SUFU mutation carriers, MB in infants is the most frequent tumor but the spectrum also includes typical Gorlin syndrome tumors (BCC, meningiomas, and ovarian stromal/fibrous tumors) either as first tumors or as second malignancies. This broad tumor spectrum and the high risk of second malignancies justify the implementation of specific cancer surveillance programs.

Clinical and mutational profiles of adult medulloblastoma groups

Adult medulloblastomas are clinically and molecularly understudied due to their rarity. We performed molecular grouping, targeted sequencing, and TERT promoter Sanger sequencing on a cohort of 99 adult medulloblastomas. SHH made up 50% of the cohort, whereas Group 3 (13%) was present in comparable proportion to WNT (19%) and Group 4 (18%). In contrast to paediatric medulloblastomas, molecular groups had no prognostic impact in our adult cohort (p = 0.877). Most frequently mutated genes were TERT (including promoter mutations, mutated in 36% cases), chromatin modifiers KMT2D (31%) and KMT2C (30%), TCF4 (31%), PTCH1 (27%) and DDX3X (24%). Adult WNT patients showed enrichment of TP53 mutations (6/15 WNT cases), and 3/6 TP53-mutant WNT tumours were of large cell/anaplastic histology.Adult SHH medulloblastomas had frequent upstream pathway alterations (PTCH1 and SMO mutations) and few downstream alterations (SUFU mutations, MYCN amplifications). TERT promoter mutations were found in 72% of adult SHH patients, and were restricted to this group. Adult Group 3 tumours lacked hallmark MYC amplifications, but had recurrent mutations in KBTBD4 and NOTCH1. Adult Group 4 tumours harboured recurrent mutations in TCF4 and chromatin modifier genes. Overall, amplifications of MYC and MYCN were rare (3%). Since molecular groups were not prognostic, alternative prognostic markers are needed for adult medulloblastoma. KMT2C mutations were frequently found across molecular groups and were associated with poor survival (p = 0.002). Multivariate analysis identified histological type (p = 0.026), metastasis (p = 0.031) and KMT2C mutational status (p = 0.046) as independent prognosticators in our cohort. In summary, we identified distinct clinical and mutational characteristics of adult medulloblastomas that will inform their risk stratification and treatment.

PATH-34. GENETIC PROFILING OF AGGRESSIVE MENINGIOMAS REVEAL DIVERSE SPECTRUM OF ACCOMPANYING ALTERATIONS BEYOND NF2 INACTIVATION

Abstract BACKGROUND Meningiomas are the most common primary central nervous system tumor in adults. The majority are clinically indolent and WHO grade I. However, 20-30% are WHO grade II and 1-3% are WHO grade III, which have shorter progression-free (PFS) and overall survival. A subset of grade I meningiomas also follow an aggressive course, requiring serial resection and/or radiotherapy, similar to high-grade meningiomas. The objective of this study was to characterize the genetic alterations in meningiomas with an aggressive clinical course. METHODS Targeted next-generation sequencing (NGS) of 40 aggressive meningiomas was performed using the UCSF500 cancer panel, which assesses ~500 cancer-related genes. Information on patient demographics, tumor histopathology, and treatment history was also collected. RESULTS Meningiomas analyzed included 15 (38%) WHO grade I, 11 (28%) WHO grade II, and 13 (33%) WHO grade III. At the time of genetic profiling, 71% of patients had received prior treatment (68% surgery, 48% fractionated radiotherapy, 23% radiosurgery). The most commonly altered gene was NF2, with 71% of tumors demonstrating biallelic inactivation. Other common alterations included biallelic CDKN2A/B deletion (15%) and TERT amplification or promoter mutation (13%). Other recurrent alterations involved SUFU (8%), and ARID1A, ATM, BAP1, DMD, KDM6A, and PTEN (each 5%). Genes which are commonly altered in indolent WHO grade I meningiomas, such as AKT1, KLF4, PIK3CA, SMO, and TRAF7, were intact in this cohort. CONCLUSIONS The additional genetic alterations beyond NF2 inactivation that drive aggressive meningiomas are diverse and include homozygous deletion of CDKN2A (negative regulator of cyclin-dependent kinases 4/6), inactivating mutations in SUFU (a negative regulator of Hedgehog signaling), homozygous deletion of PTEN (a negative regulator of mTOR signaling), and mutations/deletions in epigenetic regulatory factors (e.g. ARID1A, KDM6A). Clinical trials are needed to assess the efficacy of therapeutics targeting these specific pathways in patients with meningiomas refractory to conventional treatments.