Disease Evolution Monitored by Serial Cerebrospinal Fluid Liquid Biopsies in Two Cases of Recurrent Medulloblastoma.

Medulloblastoma is the most common malignant brain tumor in childhood. Initial treatment generally includes surgery, irradiation, and chemotherapy. Approximately 20-30% of patients will experience a recurrence, which portends a very poor prognosis. The current standard of care for evaluation for relapse includes radiographic surveillance with magnetic resonance imaging at regular intervals. The presence of circulating tumor DNA in the cerebrospinal fluid has been demonstrated to be a predictor of a higher risk of progression in a research setting for patients with medulloblastoma treated on a prospective single institution clinical trial. We have previously published and clinically validated a liquid-biopsy-based genetic assay utilizing low-pass whole genome sequencing to detect copy number alterations in circulating tumor DNA. Here, we present two teenage patients with posterior fossa medulloblastoma with recurrent disease who have been monitored with serial liquid biopsies showing tumor evolution over time, demonstrating the clinical utility of these approaches.

Translational considerations for immunotherapy clinical trials in pediatric neuro-oncology.

While immunotherapy for pediatric cancer has made great strides in recent decades, including the FDA approval of agents such as dinutuximab and tisgenlecleucel, these successes have rarely impacted children with pediatric central nervous system (CNS) tumors. As our understanding of the biological underpinnings of these tumors evolves, new immunotherapeutics are undergoing rapid clinical translation specifically designed for children with CNS tumors. Most recently, there have been notable clinical successes with oncolytic viruses, vaccines, adoptive cellular therapy, and immune checkpoint inhibition. In this article, the immunotherapy working group of the Pacific Pediatric Neuro-Oncology Consortium (PNOC) reviews the current and future state of immunotherapeutic CNS clinical trials with a focus on clinical trial development. Based on recent therapeutic trials, we discuss unique immunotherapy clinical trial challenges, including toxicity considerations, disease assessment, and correlative studies. Combinatorial strategies and future directions will be addressed. Through internationally collaborative efforts and consortia, we aim to direct this promising field of immuno-oncology to the next frontier of successful application against pediatric CNS tumors.

Pineoblastoma in children less than six years of age: The Head Start I, II, and III experience.

BACKGROUND: We report the outcomes of patients with pineoblastoma and trilateral retinoblastoma syndrome enrolled on the Head Start (HS) I-III trials. METHODS: Twenty-three children were enrolled prospectively between 1991 and 2009. Treatment included maximal surgical resection followed by five cycles of intensive chemotherapy and consolidation with marrow-ablative chemotherapy and autologous hematopoietic cell rescue (HDCx/AuHCR). Irradiation following consolidation was reserved for children over six years of age or those with residual tumor at the end of induction. RESULTS: Median age was 3.12 years (range, 0.44-5.72). Three patients withdrew from the study treatment and two patients experienced chemotherapy-related death. Eight patients experienced progressive disease (PD) during induction chemotherapy and did not proceed to HDCx/AuHCR. Ten patients received HDCx/AuHCR; eight experienced PD post-consolidation. Seven patients received craniospinal irradiation (CSI) with a median dose of 20.7 Gy (range, 18-36 Gy) with boost(s) (median dose 27 Gy; range, 18-36 Gy); three received CSI as adjuvant therapy (two post-HDCx/AuHCR) and four upon progression/recurrence. The five-year progression-free survival (PFS) and overall survival (OS) were 9.7% (95% confidence intervals [CI]: 2.6%-36.0%) and 13% (95% CI: 4.5%-37.5%), respectively. Only three patients survived beyond five years. Favorable OS prognostic factors were CSI (hazard ratio [HR] = 0.30 [0.11-0.86], P = 0.025) and HDCx/AuHCR (HR = 0.40 [0.16-0.99], P = 0.047). CONCLUSIONS: Within the HS I-III trials, CSI and HDCx/AuHCR were statistically associated with improved survival. The high PD rate during later induction cycles and following consolidation chemotherapy warrants consideration of fewer induction cycles prior to consolidation and the potential intensification of consolidation with multiple cycles of marrow-ablative chemotherapy and irradiation.

Mutations in the sonic hedgehog pathway cause macrocephaly-associated conditions due to crosstalk to the PI3K/AKT/mTOR pathway.

The hedgehog (Hh) pathway is highly conserved and required for embryonic patterning and determination. Mutations in the Hh pathway are observed in sporadic tumors as well as under syndromic conditions. Common to these syndromes are the findings of polydactyly/syndactyly and brain overgrowth. The latter is also a finding most commonly observed in the cases of mutations in the PI3K/AKT/mTOR pathway. We have identified novel Hh pathway mutations and structural copy number variations in individuals with somatic overgrowth, macrocephaly, dysmorphic facial features, and developmental delay, which phenotypically closely resemble patients with phosphatase and tensin homolog (PTEN) mutations. We hypothesized that brain overgrowth and phenotypic overlap with syndromic overgrowth syndromes in these cases may be due to crosstalk between the Hh and PI3K/AKT/mTOR pathways. To test this, we modeled disease-associated variants by generating PTCH1 and Suppressor of Fused (SUFU) heterozygote cell lines using the CRISPR/Cas9 system. These cells demonstrate activation of PI3K signaling and increased phosphorylation of its downstream target p4EBP1 as well as a distinct cellular phenotype. To further investigate the mechanism underlying this crosstalk, we treated human neural stem cells with sonic hedgehog (SHH) ligand and performed transcriptional analysis of components of the mTOR pathway. These studies identified decreased expression of a set of mTOR negative regulators, leading to its activation. We conclude that there is a significant crosstalk between the SHH and PI3K/AKT/mTOR. We propose that this crosstalk is responsible for why mutations in PTCH1 and SUFU lead to macrocephaly phenotypes similar to those observed in PTEN hamartoma and other overgrowth syndromes associated with mutations in PI3K/AKT/mTOR pathway genes.

Neoadjuvant anti-PD-1 immunotherapy promotes a survival benefit with intratumoral and systemic immune responses in recurrent glioblastoma.

Glioblastoma is the most common primary malignant brain tumor in adults and is associated with poor survival. The Ivy Foundation Early Phase Clinical Trials Consortium conducted a randomized, multi-institution clinical trial to evaluate immune responses and survival following neoadjuvant and/or adjuvant therapy with pembrolizumab in 35 patients with recurrent, surgically resectable glioblastoma. Patients who were randomized to receive neoadjuvant pembrolizumab, with continued adjuvant therapy following surgery, had significantly extended overall survival compared to patients that were randomized to receive adjuvant, post-surgical programmed cell death protein 1 (PD-1) blockade alone. Neoadjuvant PD-1 blockade was associated with upregulation of T cell- and interferon-γ-related gene expression, but downregulation of cell-cycle-related gene expression within the tumor, which was not seen in patients that received adjuvant therapy alone. Focal induction of programmed death-ligand 1 in the tumor microenvironment, enhanced clonal expansion of T cells, decreased PD-1 expression on peripheral blood T cells and a decreasing monocytic population was observed more frequently in the neoadjuvant group than in patients treated only in the adjuvant setting. These findings suggest that the neoadjuvant administration of PD-1 blockade enhances both the local and systemic antitumor immune response and may represent a more efficacious approach to the treatment of this uniformly lethal brain tumor.

Expression of PD-1 by T Cells in Malignant Glioma Patients Reflects Exhaustion and Activation.

PURPOSE: Glioblastoma (GBM) is the most common primary malignant tumor in the central nervous system. Our recent preclinical work has suggested that PD-1/PD-L1 plays an important immunoregulatory role to limit effective antitumor T-cell responses induced by active immunotherapy. However, little is known about the functional role that PD-1 plays on human T lymphocytes in patients with malignant glioma.Experimental Design: In this study, we examined the immune landscape and function of PD-1 expression by T cells from tumor and peripheral blood in patients with malignant glioma. RESULTS: We found several differences between PD-1+ tumor-infiltrating lymphocytes (TIL) and patient-matched PD-1+ peripheral blood T lymphocytes. Phenotypically, PD-1+ TILs exhibited higher expression of markers of activation and exhaustion than peripheral blood PD-1+ T cells, which instead had increased markers of memory. A comparison of the T-cell receptor variable chain populations revealed decreased diversity in T cells that expressed PD-1, regardless of the location obtained. Functionally, peripheral blood PD-1+ T cells had a significantly increased proliferative capacity upon activation compared with PD-1- T cells. CONCLUSIONS: Our evidence suggests that PD-1 expression in patients with glioma reflects chronically activated effector T cells that display hallmarks of memory and exhaustion depending on its anatomic location. The decreased diversity in PD-1+ T cells suggests that the PD-1-expressing population has a narrower range of cognate antigen targets compared with the PD-1 nonexpression population. This information can be used to inform how we interpret immune responses to PD-1-blocking therapies or other immunotherapies.

Risk of malignant childhood germ cell tumors in relation to demographic, gestational, and perinatal characteristics.

BACKGROUND: Childhood germ cell tumors (GCTs) are a rare assortment of neoplasms, with mostly unknown etiology, that are believed to originate very early in life. Few studies have examined risk factors by histologic subtype, despite evidence of different risk profiles. MATERIALS AND METHODS: In this population-based case-control study, 451 childhood malignant GCT cases ages 0-5 years were identified from the California Cancer Registry. Differentiating between common histologic subtypes, we identified 181 yolk sac tumors, 216 teratomas, and 54 rarer subtypes. Cases were linked to their birth certificates and 271,381 controls, frequency matched by birth year, were randomly selected from California birthrolls to investigate the contributions of demographic, gestational, and pregnancy factors using unconditional logistic regression analysis. RESULTS: Compared to non-Hispanic whites, Asian/Pacific Islander children were at an increased risk for developing GCTs (odds ratio [OR]=1.94; 95% confidence interval [CI]=1.47, 2.56). Among pregnancy complications and procedures, yolk sac tumors were positively associated with the presence of fetopelvic disproportion (OR=2.97; 95% CI=1.55, 5.68), while teratomas were strongly associated with polyhydramnios or oligohydramnios (OR=14.76; 95% CI=7.21, 30.19) and the presence of an ear, face, or neck anomaly at birth (OR=93.70; 95% CI=42.14, 208.82). CONCLUSIONS: Malignant yolk sac tumors and malignant teratomas exhibited distinct demographic and gestational characteristics; additionally, complications in pregnancy and labor may be brought on by specific histologic subtypes.

Risk of Childhood Cancer by Maternal Birthplace: A Test of the Hispanic Paradox.

IMPORTANCE: The Hispanic epidemiologic paradox is the phenomenon that non-US-born Hispanic mothers who immigrate to the United States have better pregnancy outcomes than their US-born counterparts. It is unknown whether this advantage extends to childhood cancer risk. OBJECTIVE: To determine whether the risk for childhood cancers among Hispanic children varies by maternal birthplace. DESIGN, SETTING, AND PARTICIPANTS: In this population-based case-control study conducted in June 2015, cohort members were identified through California birth records of children born in California from January 1, 1983, to December 31, 2011. Information on cancer diagnoses was obtained from California Cancer Registry records from 1988 to 2012. Cases (n = 13 666) were identified from among children younger than 6 years in the California Cancer Registry and matched to California birth certificates. Control children (n = 15 513 718) included all other children born in California during the same period. Maternal birthplace and ethnic ancestry were identified from the birth certificate. MAIN EXPOSURES: Maternal race/ethnicity and birthplace. MAIN OUTCOMES AND MEASURES: We used Cox proportional hazards modeling to estimate hazard ratios (HRs) of childhood cancer. RESULTS: Included in the study were 4 246 295 children of non-Hispanic white mothers (51.3% male), 2 548 822 children of US-born Hispanic mothers (51.0% male), and 4 397 703 children of non-US-born Hispanic mothers (51.0% male). Compared with children of non-Hispanic white mothers, the children of non-US-born Hispanic mothers had a reduced risk for glioma (HR, 0.50; 95% CI, 0.44-0.58), astrocytoma (HR, 0.43; 95% CI, 0.36-0.51), neuroblastoma (HR, 0.47; 95% CI, 0.40-0.54), and Wilms tumor (HR, 0.70; 95% CI, 0.59-0.82). For these cancer types, the risk estimates for children of US-born Hispanic mothers fell between those of the children of US-born white and non-US-born Hispanic mothers. Children of Mexican-born mothers had a higher risk of yolk sac tumors (HR, 1.46; 95% CI, 0.99-2.17), while children of US-born Hispanic mothers with ancestry from countries other than Mexico had a higher risk for unilateral retinoblastoma (HR, 2.03; 95% CI, 1.33-3.11). CONCLUSIONS AND RELEVANCE: For several cancers, we observed differential risk by maternal place of birth. Examining the differences in health behaviors and environment between Hispanic groups may shed light on childhood cancer etiology.

Smoking in pregnancy and risk of cancer among young children: A population-based study.

Smoking during pregnancy is a plausible risk factor for childhood cancer, yet previous studies have yielded conflicting results, and few prospective studies have been published. Data on maternal smoking were obtained from California birth certificates. We linked California birth certificates (births 2007-2011) with California Cancer Registry records for childhood cancer cases (diagnosed January 2007-September 2013) that were ages 5 or younger at diagnosis (N cases = 2,021). Controls (N = 40,356) were frequency-matched by birth year and randomly selected from birth certificate records. We used unconditional logistic regression to obtain odds ratios (OR) and 95% confidence intervals (CI) to assess the association between smoking during pregnancy and childhood cancer. We observed positive associations for gliomas (OR = 1.8, 95% CI: 1.0-3.4) and retinoblastoma (OR = 3.0, 95% CI: 1.4-6.6), particularly bilateral retinoblastoma (OR = 9.4, 95% CI 3.6-24.7) with maternal smoking in pregnancy. Maternal smoking during pregnancy may be a risk factor for retinoblastoma and certain types of childhood brain tumors.

TCR Sequencing Can Identify and Track Glioma-Infiltrating T Cells after DC Vaccination.

Although immunotherapeutic strategies are emerging as adjunctive treatments for cancer, sensitive methods of monitoring the immune response after treatment remain to be established. We used a novel next-generation sequencing approach to determine whether quantitative assessments of tumor-infiltrating lymphocyte (TIL) content and the degree of overlap of T-cell receptor (TCR) sequences in brain tumors and peripheral blood were predictors of immune response and overall survival in glioblastoma patients treated with autologous tumor lysate-pulsed dendritic cell immunotherapy. A statistically significant correlation was found between a higher estimated TIL content and increased time to progression and overall survival. In addition, we were able to assess the proportion of shared TCR sequences between tumor and peripheral blood at time points before and after therapy, and found the level of TCR overlap to correlate with survival outcomes. Higher degrees of overlap, or the development of an increased overlap following immunotherapy, was correlated with improved clinical outcome, and may provide insights into the successful, antigen-specific immune response. Cancer Immunol Res; 4(5); 412-8. ©2016 AACR.

Childhood Exposures and Risk of Malignancy in Adulthood.

Pediatricians have significant roles in preventive health care, and understanding how various exposures during childhood can have long-lasting effects on cancer risk is critical in promoting future health. With the exception of rare genetic syndromes conferring increased cancer susceptibility, most cancers are considered idiopathic and may be influenced by modifiable exposures and risks. This review aims to serve as a brief overview of a subset of known exposures during childhood that have been associated with an increased risk of malignancy in adulthood, including the effects of radiation, chemotherapy, pesticides, nutrition, puberty, and infection.

PID1 (NYGGF4), a new growth-inhibitory gene in embryonal brain tumors and gliomas.

PURPOSE: We present here the first report of PID1 (Phosphotyrosine Interaction Domain containing 1; NYGGF4) in cancer. PID1 was identified in 2006 as a gene that modulates insulin signaling and mitochondrial function in adipocytes and muscle cells. EXPERIMENTAL DESIGN AND RESULTS: Using four independent medulloblastoma datasets, we show that mean PID1 mRNA levels were lower in unfavorable medulloblastomas (groups 3 and 4, and anaplastic histology) compared with favorable medulloblastomas (SHH and WNT groups, and desmoplastic/nodular histology) and with fetal cerebellum. In two large independent glioma datasets, PID1 mRNA was lower in glioblastomas (GBM), the most malignant gliomas, compared with other astrocytomas, oligodendrogliomas and nontumor brains. Neural and proneural GBM subtypes had higher PID1 mRNA compared with classical and mesenchymal GBM. Importantly, overall survival and radiation-free progression-free survival were longer in medulloblastoma patients whose tumors had higher PID1 mRNA (univariate and multivariate analyses). Higher PID1 mRNA also correlated with longer overall survival in patients with glioma and GBM. In cell culture, overexpression of PID1 inhibited colony formation in medulloblastoma, atypical teratoid rhabdoid tumor (ATRT), and GBM cell lines. Increasing PID1 also increased cell death and apoptosis, inhibited proliferation, induced mitochondrial depolaization, and decreased serum-mediated phosphorylation of AKT and ERK in medulloblastoma, ATRT, and/or GBM cell lines, whereas siRNA to PID1 diminished mitochondrial depolarization. CONCLUSIONS: These data are the first to link PID1 to cancer and suggest that PID1 may have a tumor inhibitory function in these pediatric and adult brain tumors.

A phase I study of vincristine, irinotecan, temozolomide and bevacizumab (vitb) in pediatric patients with relapsed solid tumors.

BACKGROUND: To determine the maximum tolerated dose (MTD) and dose limiting toxicity (DLT) of irinotecan administered in combination with vincristine, temozolomide and bevacizumab in children with refractory solid tumors. METHODS: The study design included two dose levels (DL) of irinotecan given intravenously once daily for 5 consecutive days (DL1: 30 mg/m(2), and DL2: 50 mg/m(2)), combined with vincristine 1.5 mg/m(2) on days 1 and 8, temozolomide 100 mg/m(2) on days 1-5, and bevacizumab 15mg/kg on day 1, administered every 21 days for a maximum of 12 cycles. RESULTS: Thirteen patients were enrolled and 12 were evaluable for toxicity Dose limiting toxicity observed included grade 3 hyperbilirubinemia in 1 of 6 patients on DL1, and grade 3 colitis in 1 of 6 patients on DL2. DL 2 was the determined MTD. A total of 87 cycles were administered. Myelosuppression was mild. Grade 1-2 diarrhea occurred in the majority of cycles with grade 3 diarrhea occurring in only one cycle. Grade 2 hypertension developed in two patients. Severe hemorrhage, intestinal perforation, posterior leukoencephalopathy or growth plate abnormalities were not observed. Objective responses were noted in three Wilms tumor patients and one each of medulloblastoma and hepatocellular carcinoma. Five patients completed all 12 cycles of protocol therapy. CONCLUSIONS: Irinotecan 50 mg/m(2)/day for 5 days was the MTD when combined with vincristine, temozolomide and bevacizumab administered on a 21 day schedule. Encouraging anti-tumor activity was noted. TRIAL REGISTRATION: ClinicalTrials.gov; NCT00993044; http://clinicaltrials.gov/show/NCT00993044.

Microdeletion del(22)(q12.2) encompassing the facial development-associated gene, MN1 (meningioma 1) in a child with Pierre-Robin sequence (including cleft palate) and neurofibromatosis 2 (NF2): a case report and review of the literature.

BACKGROUND: Pierre-Robin sequence (PRS) is defined by micro- and/or retrognathia, glossoptosis and cleft soft palate, either caused by deformational defect or part of a malformation syndrome. Neurofibromatosis type 2 (NF2) is an autosomal dominant syndrome caused by mutations in the NF2 gene on chromosome 22q12.2. NF2 is characterized by bilateral vestibular schwannomas, spinal cord schwannomas, meningiomas and ependymomas, and juvenile cataracts. To date, NF2 and PRS have not been described together in the same patient. CASE PRESENTATION: We report a female with PRS (micrognathia, cleft palate), microcephaly, ocular hypertelorism, mental retardation and bilateral hearing loss, who at age 15 was also diagnosed with severe NF2 (bilateral cerebellopontine schwannomas and multiple extramedullary/intradural spine tumors). This is the first published report of an individual with both diagnosed PRS and NF2. High resolution karyotype revealed 46, XX, del(22)(q12.1q12.3), FISH confirmed a deletion encompassing NF2, and chromosomal microarray identified a 3,693 kb deletion encompassing multiple genes including NF2 and MN1 (meningioma 1).Five additional patients with craniofacial dysmorphism and deletion in chromosome 22-adjacent-to or containing NF2 were identified in PubMed and the DECIPHER clinical chromosomal database. Their shared chromosomal deletion encompassed MN1, PITPNB and TTC28. MN1, initially cloned from a patient with meningioma, is an oncogene in murine hematopoiesis and participates as a fusion gene (TEL/MN1) in human myeloid leukemias. Interestingly, Mn1-haploinsufficient mice have abnormal skull development and secondary cleft palate. Additionally, Mn1 regulates maturation and function of calvarial osteoblasts and is an upstream regulator of Tbx22, a gene associated with murine and human cleft palate. This suggests that deletion of MN1 in the six patients we describe may be causally linked to their cleft palates and/or craniofacial abnormalities. CONCLUSIONS: Thus, our report describes a NF2-adjacent chromosome 22q12.2 deletion syndrome and is the first to report association of MN1 deletion with abnormal craniofacial development and/or cleft palate in humans.