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Based on biology and pre-clinical data, bromodomain and extra-terminal (BET) inhibitors have at least three potential roles in paediatric malignancies: NUT (nuclear protein in testis) carcinomas, MYC/MYCN-driven cancers and fusion-driven malignancies. However, there are now at least 10 BET inhibitors in development, with a limited relevant paediatric population in which to evaluate these medicinal products. Therefore, a meeting was convened with the specific aim to develop a consensus among relevant biopharmaceutical companies, academic researchers, as well as patient and family advocates, about the development of BET inhibitors, including prioritisation and their specific roles in children. Although BET inhibitors have been in clinical trials in adults since 2012, the first-in-child study (BMS-986158) only opened in 2019. In the future, when there is strong mechanistic rationale or pre-clinical activity of a class of medicinal product in paediatrics, early clinical evaluation with embedded correlative studies of a member of the class should be prioritised and rapidly executed in paediatric populations. There is a strong mechanistic and biological rationale to evaluate BET inhibitors in paediatrics, underpinned by substantial, but not universal, pre-clinical data. However, most pan-BET inhibitors have been challenging to administer in adults, since monotherapy results in only modest anti-tumour activity and provides a narrow therapeutic index due to thrombocytopenia. It was concluded that it is neither scientifically justified nor feasible to undertake simultaneously early clinical trials in paediatrics of all pan-BET inhibitors. However, there is a clinical need for global access to BET inhibitors for patients with NUT carcinoma, a very rare malignancy driven by bromodomain fusions, with proof of concept of clinical benefit in a subset of patients treated with BET inhibitors. Development and regulatory pathway in this indication should include children and adolescents as well as adults. Beyond NUT carcinoma, it was proposed that further clinical development of other pan-BET inhibitors in children should await the results of the first paediatric clinical trial of BMS-986158, unless there is compelling rationale based on the specific agent of interest. BDII-selective inhibitors, central nervous system–penetrant BET inhibitors (e.g. CC-90010), and those dual-targeting BET/p300 bromodomain are of particular interest and warrant further pre-clinical investigation. This meeting emphasised the value of a coordinated and integrated strategy to drug development in paediatric oncology. A multi-stakeholder approach with multiple companies developing a consensus with academic investigators early in the development of a class of compounds, and then engaging regulatory agencies would improve efficiency, productivity, conserve resources and maximise potential benefit for children with cancer.

Pediatric low-grade gliomas (pLGGs) are the most common CNS tumor of childhood and comprise a heterogenous group of tumors. Children with progressive pLGG often require numerous treatment modalities including surgery, chemotherapy, rarely radiation therapy and, more recently, molecularly targeted therapy. We describe our institutional experience using the MEK inhibitor, trametinib, for recurrent/progressive pLGGs. We performed a retrospective, IRB-approved, chart review of all pediatric patients treated with trametinib for recurrent/progressive pLGGs at Dana-Farber/Boston Children’s Cancer and Blood Disorder Center between 2016 and 2018. Eleven patients were identified, of which 10 were evaluable for response. Median age at commencement of trametinib treatment was 14.7 years (range 7.3–25.9 years). Tumor molecular status included KIAA1549-BRAF fusion (n = 4), NF1 mutation (n = 4), FGFR mutation (n = 1) and CDKN2A loss (n = 1). Median number of prior treatment regimens was 5 (range 1–12). Median duration of treatment with trametinib was 19.2 months (range 3.8–29.8 months). Based on modified RANO criteria, best responses included partial (n = 2), minor response (n = 2) and stable disease (n = 6). Two patients remain on therapy (29.8 and 25.9 months, respectively). The most common toxicities attributable to trametinib were rash, fatigue and gastrointestinal disturbance. Five patients required dose reduction for toxicities. Two patients experienced significant intracranial hemorrhage (ICH) while on trametinib. While it is unclear whether ICH was directly attributable to trametinib, therapy was discontinued. Trametinib appears to be an effective treatment for patients with recurrent/progressive pLGG. The toxicities of this therapy warrant further investigation, with particular attention to the potential risk for intracranial hemorrhage. Early phase multi-institutional clinical trials are underway.

Background Off‐label drug prescribing is common in pediatric clinical medicine, though the extent and impact of this practice in pediatric oncology has not yet been characterized. Methods We completed a retrospective single‐institution cohort study evaluating prevalence, characteristics, and clinical outcomes of off‐label prescribing of 108 FDA‐approved targeted anticancer drugs in patients, Off‐label prescribing patterns and outcomes with targeted anticancer agents have not been previously described in pediatric oncology. In this analysis from a large pediatric cancer center, off‐label prescribing of FDA‐approved targeted therapies was common, increasing, encompassed a broad sample of targeted agents, and was tolerable.

Immune checkpoint inhibition through PD-1 and CTLA-4 blockade has shown efficacy in some adult malignancies and generated interest in pediatrics, including central nervous system (CNS) tumors. We describe our experience with immune checkpoint inhibition in recurrent/refractory pediatric CNS tumors. We performed a retrospective chart review of pediatric patients with recurrent or refractory CNS tumors treated with ipilimumab, nivolumab and/or pembrolizumab at Dana-Farber/Boston Children’s Hospital between 2018 and 2019. Eleven patients were identified. Diagnoses included diffuse intrinsic pontine glioma (DIPG) (n = 2), high-grade glioma (HGG) (n = 5), ependymoma (n = 1), craniopharyngioma (n = 1), high-grade neuroepithelial tumor (n = 1) and non-germinomatous germ cell tumor (NGGCT) (n = 1). Eight patients had recurrent disease, while three had refractory disease. Nine patients received combination therapy (ipilimumab/nivolumab); two patients received either nivolumab or pembrolizumab. Median time from diagnosis-to-treatment was 8 months (range 0.8–156). All patients received prior radiation therapy (RT), with median time from RT-to-immunotherapy was 3.8 years. One patient received concurrent then adjuvant immunotherapy with RT. Median duration of treatment was 6.1 months (range 1–25). Therapy was discontinued in nine patients: seven due to disease progression and two due to toxicity (colitis; transaminitis). Other pertinent toxicities included Type 1 diabetes mellitus, hypothyroidism and skin toxicity. Based on iRANO criteria, best responses included partial response (n = 3), stable disease (n = 7) and progressive disease (n = 1). Durable response was noted in two patients. Immune checkpoint inhibition was relatively well tolerated in a cohort of pediatric patients spanning several CNS tumor diagnoses. Results from prospective clinical trials will be critical to inform clinical decisions.

Pediatric brain tumors are associated with high morbidity and mortality, in part due to insufficient understanding of tumor biology. With limited tissue allocation for research from surgical specimens, a key barrier to improving biological understanding, brain tumor autopsies have become an increasingly valuable resource. This study reviews the brain tumor autopsy practice at our institution and describes specific emerging research utilization patterns beyond the clinical autopsy report. We performed a retrospective analysis of brain tumor autopsies at Boston Children’s Hospital (BCH) between 2007 and 2017 and reviewed their consents, neuropathology reports and final diagnoses. We reviewed the method of tissue triaging for research consented autopsies (bioregistry, frozen and fresh tissue) and documented their specific uses. Ninety-six deaths at BCH were due to brain tumors; 56 autopsies were performed (58.3%), of which 49 (87.5%) were consented for research. Tumor mapping was performed on all cases and tissue was allocated for DNA- and RNA-based sequencing studies (published and ongoing). Three tissue allocations with a postmortem interval of 8 h or less resulted in successful cell lines. Tissue from 14 autopsies was contributed to the National DIPG Registry. Our institutional pediatric brain tumor autopsy clinical experience demonstrates the increased utility and wide utilization of autopsy-derived tissue for multiple types of research. These results support the increased efforts to obtain research consent for brain tumor autopsy and active collection of unfixed autopsy material in the molecular era.

Background Ependymoma is the third most common malignant CNS tumor in children. Despite multimodal therapy, prognosis of relapsed ependymoma remains poor. Approaches to therapy for relapsed ependymoma are varied. We present a single-institution retrospective review of the outcomes after first relapse of intracranial ependymoma in children. Procedure We performed a retrospective, IRB-approved chart review of patients with recurrent intracranial ependymoma treated at Dana-Farber/Boston Children's Cancer and Blood Disorders Center from 1990 to 2019. Results Thirty-four patients with relapsed intracranial ependymoma were identified. At initial diagnosis, 11 patients had supratentorial disease, 22 with posterior fossa disease and one with metastatic disease. Median time-to-first relapse was 14.9 months from initial diagnosis (range 1.4-52.5). Seven patients had metastatic disease at first relapse. Gross total resection (GTR) was associated with improved 5-year progression-free survival (PFS) relative to subtotal resection (STR) and no surgery (p = .005). Localized disease at relapse was associated with improved 5-year overall survival (OS) when compared to metastatic disease (p = .02). Irradiation at first relapse seemed to delay progression but was not associated with statistically prolonged PFS or OS. Tumor location, histology, and chromosomal 1q status did not impact outcome at first relapse, although available molecular data were limited making definitive conclusions difficult. Median time-to-second relapse was 10 months (range 0.7-124). Five-year PFS and OS after first relapse were 19.9% and 45.1%, respectively. Median PFS and OS were 10.0 and 52.5 months after first relapse, respectively. Conclusions Relapsed intracranial ependymoma has a poor prognosis despite multimodal therapy. Novel therapeutic strategies are desperately needed for this disease.

Population-based cancer registries (PBCRs) generate measures of cancer incidence and survival that are essential for cancer surveillance, research, and cancer control strategies. In 2014, the Toronto Paediatric Cancer Stage Guidelines were developed to standardise how PBCRs collect data on the stage at diagnosis for childhood cancer cases. These guidelines have been implemented in multiple jurisdictions worldwide to facilitate international comparative studies of incidence and outcome. Robust stratification by risk also requires data on key non-stage prognosticators (NSPs). Key experts and stakeholders used a modified Delphi approach to establish principles guiding paediatric cancer NSP data collection. With the use of these principles, recommendations were made on which NSPs should be collected for the major malignancies in children. The 2014 Toronto Stage Guidelines were also reviewed and updated where necessary. Wide adoption of the resultant Paediatric NSP Guidelines and updated Toronto Stage Guidelines will enhance the harmonisation and use of childhood cancer data provided by PBCRs.

INTRODUCTION The incidence of IDH mutations in pediatric glioma is unclear. Recent publications suggest rates ranging between 0–20%. Therapy poses challenges as it is unclear if the biology and prognosis of pediatric IDH-mutant gliomas are identical to adults. METHODS We performed an IRB approved, systematic retrospective search for IDH-mutant gliomas in the Dana-Farber Cancer Institute/Boston Children’s Hospital database between 2009–2018, analyzing incidence, demographics, histology, co-occurring genetic alterations and outcome. RESULTS We identified 575 patients with glioma, ages 0–21 years. Of these, 394 underwent biopsy/resection (0–9 years:n=204; 10–21 years:n=190), with 294 genetic testing. Fifteen of 294 tumors (5%) were IDH1-mutant. Among patients 0–9 years and 10–21 years, 1/156 (0.6%) and 14/138 (10%) had IDH1-mutant tumors, respectively. Among patients 10–21 year old, 13/115 low-grade gliomas were IDH1-mutant (11%). High-grade gliomas accounted for the remaining 23, with one IDH1-mutant glioma (4%). Most common co-occurring genetic alterations for diffuse astrocytoma (n=12) were TP53 (n=9) and ATRX (n=2). Three patients with IDH1-mutant oligodendrogliomas had 1p/19q deletion. Eleven IDH1-mutant patients were evaluable for outcomes with median follow-up of five years. Five-year radiation-free, progression-free and overall survival for patients with low-grade histology were 76% and 100%, respectively. One patient with high-grade glioma recurred 1.2 years after upfront chemo-radiation and died soon after recurrence. CONCLUSION IDH-mutant gliomas comprise a small proportion of pediatric gliomas. Incidence rate is higher in the second decade of life. Comparative analyses between pediatric IDH-mutant gliomas and adult historical cohorts are currently underway, evaluating outcomes, radiation therapy and frequency of malignant transformation.

INTRODUCTION Immune checkpoint inhibition through PD-1 and CTLA-4 blockade has shown efficacy in some adult malignancies and is being investigated in pediatrics. We describe our institutional experience with immune checkpoint inhibition in pediatric CNS tumors. METHODS We performed a retrospective chart review of patients with recurrent, progressive, or refractory pediatric CNS tumors treated with immunotherapy at Dana-Farber/Boston Children’s Hospital between 2018–2019. RESULTS Eleven patients were identified, with median age of 11 years (range:3–9). Diagnoses included DIPG (n=3), HGG (n=4), ependymoma (n=1), craniopharyngioma (n=1), HGNET (n=1) and NGGCT (n=1). Eight patients had recurrent disease (5 local; 3 disseminated); three had refractory disease (non-recurrent). Nine patients were treated with combination therapy (ipilimumab/nivolumab); two patients received monotherapy with either nivolumab or pembrolizumab. Median time from initial diagnosis-to-treatment was 8 months (range 0.8–156). Ten patients received radiation therapy (RT) prior to immunotherapy, with one receiving concurrent RT. Median duration of treatment was 6.1 months (range:1–19). Therapy was discontinued in nine patients: seven due to disease progression and two due to adverse events (colitis, transaminitis). Other pertinent toxicities included type 1 diabetes, hypothyroidism and skin toxicity. Based on iRANO criteria, best responses included partial (n=4), stable (n=6) and progressive disease (n=1). Durable response (>12months) was noted in two patients (HGG and progressive NGGCT). CONCLUSION Immune checkpoint inhibition appears to have clinical benefit and is relatively well tolerated in this cohort of patients. Results from recently completed prospective clinical trials will be critical to inform clinical decisions.

Despite recent advances in the treatment of medulloblastoma, patients in high-risk categories still face very poor outcomes. Evidence indicates that a subpopulation of cancer stem cells contributes to therapy resistance and tumour relapse in these patients. To prevent resistance and relapse, the development of treatment strategies tailored to target subgroup specific signalling circuits in high-risk medulloblastomas might be similarly important as targeting the cancer stem cell population. We have previously demonstrated potent antineoplastic effects for the PI3Kα selective inhibitor alpelisib in medulloblastoma. Here, we performed studies aimed to enhance the anti-medulloblastoma effects of alpelisib by simultaneous catalytic targeting of the mTOR kinase. Pharmacological mTOR inhibition potently enhanced the suppressive effects of alpelisib on cancer cell proliferation, colony formation and apoptosis and additionally blocked sphere-forming ability of medulloblastoma stem-like cancer cells in vitro. We identified the HH effector GLI1 as a target for dual PI3Kα and mTOR inhibition in SHH-type medulloblastoma and confirmed these results in HH-driven Ewing sarcoma cells. Importantly, pharmacologic mTOR inhibition greatly enhanced the inhibitory effects of alpelisib on medulloblastoma tumour growth in vivo. In summary, these findings highlight a key role for PI3K/mTOR signalling in GLI1 regulation in HH-driven cancers and suggest that combined PI3Kα/mTOR inhibition may be particularly interesting for the development of effective treatment strategies in high-risk medulloblastomas.

INTRODUCTION: Pediatric low-grade gliomas (pLGGs) are the most common CNS tumor of childhood and comprise a heterogenous group of tumors. Children with progressive pLGG typically require numerous regimens of therapy including surgical resection, chemotherapy and rarely, radiation therapy. The presence of frequent genetic alterations activating the mitogen-activated-protein-kinase (MAPK) signaling pathway has recently led to a more targeted therapeutic approach. We describe our institutional experience using trametinib, an FDA-approved MEK inhibitor for recurrent/progressive pLGGs. METHODS: We performed a retrospective, IRB approved, chart review of all patients with recurrent/progressive pLGGs treated with trametinib off-study at Dana-Farber / Boston’s Children’s Cancer and Blood Disorder Center between 2016–2018. RESULTS: Eleven patients were identified, with ten evaluable for response. Median age at commencement of trametinib treatment was 14.7 years old (range 7.3–25.9 years; 6 male: 5 female). Molecular status included KIAA 1549-BRAF fusion (n=3), NF1 (n=4), FGFR mutation and heterozygous CDKN2A loss (n=1 each), unknown mutational status (n=2). Median number of prior treatment regimens was 5 (range 1–7). Median duration on treatment with trametinib was 13.4 months (range 1.5–24.8 months). Based on RANO criteria, responses included partial (n=1), minor response (n=1) and stable disease (n=5) as best response. Four patients remain on therapy with trametinib (range 1.5–24.8 months) with two patients having discontinued therapy secondary to disease progression. The most common toxicities were skin rash, fatigue and gastrointestinal disturbance. Five patients required dose reduction for toxicities. Two patients experienced intracranial hemorrhage (ICH) while on trametinib (at 5 and 498 days). While it is unclear whether ICH was directly attributable to trametinib, therapy was discontinued. CONCLUSION: Trametinib appears to be an effective treatment for patients with recurrent/progressive pLGG. The toxicities of this therapy warrant further investigation, particularly the potential risk for intracranial hemorrhage. Early phase clinical trials are underway.

INTRODUCTION: Ependymoma is the third commonest malignant CNS tumor in children. Despite multimodal therapy, prognosis of relapsed ependymoma remains poor with long-term progression-free survival (PFS) of approximately 30%. Approaches to treating relapsed ependymoma are extremely varied. Here, we describe our experience and clinical outcomes of children after first relapse of intracranial ependymoma. METHODS: We performed a retrospective, IRB approved, chart review of patients with recurrent intracranial ependymoma treated at Dana-Farber / Boston Children’s Cancer and Blood Disorder Center from 1990 to 2017. RESULTS: Thirty-four patients with relapsed intracranial ependymoma (12 ST, 21 PF, 1 metastatic) were identified. Median time-to-first-relapse was 13.7 months (range:2.0–53.8). Eight patients had metastatic disease at first relapse. Five-year PFS and overall survival (OS) after first relapse was 23.5% and 60.9%, respectively. Median PFS and OS were 12 months and 66 months. Treatments for first relapse included surgery, radiation and/or chemotherapy/biologic therapy. GTR and localized disease were associated with improved OS on univariate analysis, with GTR being an independent prognostic factor for PFS and OS on multivariate analysis (p=0.02 & 0.013, respectively). Median PFS and OS for patients with GTR was 1.5 and 13 years, respectively (versus 0.4 and 2.3 years for STR / no resection [p=0.023 & 0.001, respectively]). Eighteen patients received radiation at first relapse (14 focal radiation, 8 re-irradiation). Patients who were radiated/re-irradiated at relapse showed longer median PFS and OS, however, these did not meet statistical significance. Chemotherapeutic (n=16) and biologic agents (n=3) used in this cohort were heterogenous and did not significantly impact outcome. Median time-to-second-relapse was 10.2 months (range:2.0–124.8). CONCLUSION: Relapsed intracranial ependymoma has a poor prognosis and unrelenting chronic course despite multimodal therapy. GTR is associated with improved outcomes after first relapse and should be pursued when possible. Novel therapeutic strategies are needed for this disease.

Medulloblastoma is a highly malignant pediatric brain tumor associated with poor outcome. Developing treatments that target the cancer stem cell (CSC) population in medulloblastoma are important to prevent tumor relapse and induce long-lasting clinical responses. We utilized medulloblastoma neurospheres that display CSC characteristics and found activation of the PI3K/AKT pathway in sphere-forming cells. Of all class IA PI3Ks, only the PI3Kα isoform was required for sphere formation by medulloblastoma cells. Knockdown of p110α, but not p110β or p110δ, significantly disrupted cancer stem cell frequencies as determined by extreme limiting dilution analysis (ELDA), indicating an essential role for the PI3Kα catalytic isoform in medulloblastoma CSCs. Importantly, pharmacologic inhibition of the MAPK-interacting kinase (MNK) enhanced the antineoplastic effects of targeted PI3Kα inhibition in medulloblastoma. This indicates that MNK signaling promotes survival in medulloblastoma, suggesting dual PI3Kα and MNK inhibition may provide a novel approach to target and eliminate medulloblastoma CSCs. We also observed a significant reduction in tumor formation in subcutaneous and intracranial mouse xenograft models, which further suggests that this combinatorial approach may represent an efficient therapeutic strategy for medulloblastoma. Implications: These findings raise the possibility of a unique therapeutic approach for medulloblastoma, involving MNK targeting to sensitize medulloblastoma CSCs to PI3Kα inhibition.

Brain tumors are the most common solid tumor in children, and unfortunately, they carry the highest mortality rate of any of the pediatric cancers. The tumor itself can pose significant risk to the patient due to local effects on the central nervous system which can be life threatening if not addressed quickly. In addition, treatment can also pose significant risks to the patient as damage to the brain has a much slower recovery than any other organ in the body. This can have long-term ramifications to the patient’s overall functionality for his or her lifetime.

Medulloblastoma is the most common paediatric malignant brain cancer and there is a need for new targeted therapeutic approaches to more effectively treat these malignant tumours, which can be divided into four molecular subtypes. Here, we focus on targeting sonic hedgehog (SHH) subtype medulloblastoma, which accounts for approximately 25% of all cases. The SHH subtype relies upon cholesterol signalling for tumour growth and maintenance of tumour-initiating cancer stem cells (CSCs). To target cholesterol signalling, we employed biomimetic high-density lipoprotein nanoparticles (HDL NPs) which bind to the HDL receptor, scavenger receptor type B-1 (SCARB1), depriving cells of natural HDL and their cholesterol cargo. We demonstrate uptake of HDL NPs in SCARB1 expressing medulloblastoma cells and depletion of cholesterol levels in cancer cells. HDL NPs potently blocked proliferation of medulloblastoma cells, as well as hedgehog-driven Ewing sarcoma cells. Furthermore, HDL NPs disrupted colony formation in medulloblastoma and depleted CSC populations in medulloblastoma and Ewing sarcoma. Altogether, our findings provide proof of principle for the development of a novel targeted approach for the treatment of medulloblastoma using HDL NPs. These findings present HDL-mimetic nanoparticles as a promising therapy for sonic hedgehog (SHH) subtype medulloblastoma and possibly other hedgehog-driven cancers.

BACKGROUND: Current brain tumor therapies are focused on reducing tumor burden by inducing apoptotic and necrotic tumor cells. However, inflammation in the tumor microenvironment caused by this debris can accelerate tumor progression. Inflammation is endogenously regulated resolvins and protectins, molecules that are biosynthesized and act in the brain and cerebrospinal fluid. They clear cellular debris via local macrophages while reducing localized inflammatory cytokines. We hypothesized that control of inflammation through resolvins and protectins could represent a novel treatment modality by pharmacologically promoting the clearance of tumor cell debris by microglia, thereby depriving the surviving tumor cells of inflammatory stimuli. METHODS AND RESULTS: We show that debris generated by killing of either medulloblastoma or glial tumors (using cisplatin chemotherapy, dabrafenib targeted therapy or the epigenetic inhibitors JQ1) stimulate residual live tumor cells to grow. This effect was inhibited by nanogram levels of resolvins/protectins and without toxicity in a variety of tumor types including orthotopic models. The effect was mediated via enhanced macrophage and microglial phagocytosis of tumor cell debris and counter-regulation the secretion of pro-inflammatory cytokines/chemokines, including CCL5, TNFα, CCL2, CXCL1, and CCL4. CONCLUSIONS: We show that resolvins and protectins stimulate the clearance of tumor cell debris by stimulating macrophage and microglial phagocytosis and counter-regulating pro-inflammatory and pro-tumorigenic cytokines. This approach not only has relevance to our current approaches to cancer therapy (focused on maximal tumor cell kill), but may have an impact on the side effects of current immunotherapies where therapy induced inflammation in the tumor results in significant morbidity.

BACKGROUND: The phosphoinositide 3-kinase (PI3K) and sonic hedgehog (SHH) pathways play important roles in medulloblastoma (MB) and other pediatric cancers. Aberrant activation of the PI3K pathway has been shown to be an important regulator of cancer cell proliferation, metabolism, protein synthesis and apoptosis. Additionally, mTOR activation contributes to therapy resistance likely in part through SMO-independent activation of the transcription factor GLI. Thus we sought to evaluate the effects of combined PI3K/mTOR inhibition in medulloblastoma and Ewing sarcoma. METHODS: Medulloblastoma (DAOY and D556) and Ewing Sarcoma cell lines (TC71, RDES) were grown in 2-D culture to investigate the effects of pharmacologic inhibition of PI3K and mTOR (using BYL-719, a p110α isoform specific PI3K inhibitor and OSI-027, a catalytic inhibitor of mTOR1/2, respectively) on protein kinase signaling, cell proliferation, colony formation, intracellular localization of GLI, and GLI target gene expression. RESULTS: Of all four class I PI3Ks only the p110α isoform is required for MB cell proliferation and colony formation. Pharmacologic targeting of the p110α isoform of PI3K with BYL-719 synergized with the catalytic mTORC1/2 inhibitor OSI-027, resulting in inhibition of effector pathways, and blocked cell proliferation and colony formation in both medulloblastoma and Ewing Sarcoma. Moreover, dual PI3K/mTOR inhibition resulted in decreased nuclear localization of GLI and reduced GLI target gene expression in both pediatric tumor cell lines. CONCLUSIONS: Inhibition of p110α and mTOR exerts potent antineoplastic effects on cancer cell proliferation and transformation. This effect may be due in part to inhibition of GLI nuclear localization. Thus, besides established roles in inhibition of cancer cell proliferation and protein synthesis, dual inhibition of p110α and mTOR is particularly promising for targeting SHH-driven cancers such as medulloblastoma and Ewing sarcoma.

We summarized studies describing the prevalence of, trends in, and correlates of nonmedical exemptions from school vaccination mandates and the association of these policies with the incidence of vaccine-preventable disease. We searched 4 electronic databases for empirical studies published from 1997 to 2013 to capture exemption dynamics and qualitatively abstracted and synthesized the results. Findings from 42 studies suggest that exemption rates are increasing and occur in clusters; most exemptors questioned vaccine safety, although some exempted out of convenience. Easier state-level exemption procedures increase exemption rates and both individual and community disease risk. State laws influence exemption rates, but policy implementation, exemptors’ vaccination status, and underlying mechanisms of geographical clustering need to be examined further to tailor specific interventions.