Risk-adapted craniospinal radiotherapy followed by high-dose chemotherapy and stem-cell rescue in children with newly diagnosed medulloblastoma (St Jude Medulloblastoma-96): long-term results from a prospective, multicentre trial

BACKGROUND

Current treatment for medulloblastoma, which includes postoperative radiotherapy and 1 year of chemotherapy, does not cure many children with high-risk disease. We aimed to investigate the effectiveness of risk-adapted radiotherapy followed by a shortened period of dose-intense chemotherapy in children with medulloblastoma.

METHODS

After resection, patients were classified as having average-risk medulloblastoma (< or = 1.5 cm2 residual tumour and no metastatic disease) or high-risk medulloblastoma (> 1.5 cm2 residual disease or metastatic disease localised to neuraxis) medulloblastoma. All patients received risk-adapted craniospinal radiotherapy (23.4 Gy for average-risk disease and 36.0-39.6 Gy for high-risk disease) followed by four cycles of cyclophosphamide-based, dose-intensive chemotherapy. Patients were assessed regularly for disease status and treatment side-effects. The primary endpoint was 5-year event-free survival; we also measured overall survival. This study is registered with ClinicalTrials.gov, number NCT00003211.

FINDINGS

Of 134 children with medulloblastoma who underwent treatment (86 average-risk, 48 high-risk), 119 (89%) completed the planned protocol. No treatment-related deaths occurred. 5-year overall survival was 85% (95% CI 75-94) in patients in the average-risk group and 70% (54-84) in those in the high-risk group (p=0.04); 5-year event-free survival was 83% (73-93) and 70% (55-85), respectively (p=0.046). For the 116 patients whose histology was reviewed centrally, histological subtype correlated with 5-year event-free survival (p=0.04): 84% (74-95) for classic histology, 77% (49-100) for desmoplastic tumours, and 57% (33-80) for large-cell anaplastic tumours.

INTERPRETATION

Risk-adapted radiotherapy followed by a shortened schedule of dose-intensive chemotherapy can be used to improve the outcome of patients with high-risk medulloblastoma.

Novel somatic and germline mutations in intracranial germ cell tumours

Intracranial germ cell tumours (IGCTs) are a group of rare heterogeneous brain tumours that are clinically and histologically similar to the more common gonadal GCTs. IGCTs show great variation in their geographical and gender distribution, histological composition and treatment outcomes. The incidence of IGCTs is historically five- to eightfold greater in Japan and other East Asian countries than in Western countries, with peak incidence near the time of puberty. About half of the tumours are located in the pineal region. The male-to-female incidence ratio is approximately 3-4:1 overall, but is even higher for tumours located in the pineal region. Owing to the scarcity of tumour specimens available for research, little is currently known about this rare disease. Here we report the analysis of 62 cases by next-generation sequencing, single nucleotide polymorphism array and expression array. We find the KIT/RAS signalling pathway frequently mutated in more than 50% of IGCTs, including novel recurrent somatic mutations in KIT, its downstream mediators KRAS and NRAS, and its negative regulator CBL. Novel somatic alterations in the AKT/mTOR pathway included copy number gains of the AKT1 locus at 14q32.33 in 19% of patients, with corresponding upregulation of AKT1 expression. We identified loss-of-function mutations in BCORL1, a transcriptional co-repressor and tumour suppressor. We report significant enrichment of novel and rare germline variants in JMJD1C, which codes for a histone demethylase and is a coactivator of the androgen receptor, among Japanese IGCT patients. This study establishes a molecular foundation for understanding the biology of IGCTs and suggests potentially promising therapeutic strategies focusing on the inhibition of KIT/RAS activation and the AKT1/mTOR pathway.

A prospective, randomized study of shunt function and infections as a function of shunt placement

Much controversy still exists about the relative advantages and disadvantages of anteriorly vs. posteriorly placed shunts in terms of infection rate and duration of function. During a 27-month period, all 121 patients seen requiring new shunt insertions were prospectively randomized to anterior or posterior placement. The mean duration of follow-up was 15 months. 70% of the shunts in the posteriorly placed group vs. 59% of the shunts in the anteriorly placed group did not require further surgery during the study period. In a life-table analysis of shunt survival as a function of placement, the shunts in the posteriorly placed group 'survived' slightly longer without malfunctioning or becoming infected than the anteriorly placed shunts. Therefore, the authors conclude that anteriorly placed shunts offer no advantage over posteriorly placed shunts in terms of shunt malfunction or infection.

CNS Langerhans cell histiocytosis: Common hematopoietic origin for LCH-associated neurodegeneration and mass lesions

BACKGROUND

Central nervous system Langerhans cell histiocytosis (CNS-LCH) brain involvement may include mass lesions and/or a neurodegenerative disease (LCH-ND) of unknown etiology. The goal of this study was to define the mechanisms of pathogenesis that drive CNS-LCH.

METHODS

Cerebrospinal fluid (CSF) biomarkers including CSF proteins and extracellular BRAFV600E DNA were analyzed in CSF from patients with CNS-LCH lesions compared with patients with brain tumors and other neurodegenerative conditions. Additionally, the presence of BRAFV600E was tested in peripheral mononuclear blood cells (PBMCs) as well as brain biopsies from LCH-ND patients, and the response to BRAF-V600E inhibitor was evaluated in 4 patients with progressive disease.

RESULTS

Osteopontin was the only consistently elevated CSF protein in patients with CNS-LCH compared with patients with other brain pathologies. BRAFV600E DNA was detected in CSF of only 2/20 (10%) cases, both with LCH-ND and active lesions outside the CNS. However, BRAFV600E+ PBMCs were detected with significantly higher frequency at all stages of therapy in LCH patients who developed LCH-ND. Brain biopsies of patients with LCH-ND demonstrated diffuse perivascular infiltration by BRAFV600E+ cells with monocyte phenotype (CD14+ CD33+ CD163+ P2RY12- ) and associated osteopontin expression. Three of 4 patients with LCH-ND treated with BRAF-V600E inhibitor experienced significant clinical and radiologic improvement.

CONCLUSION

In LCH-ND patients, BRAFV600E+ cells in PBMCs and infiltrating myeloid/monocytic cells in the brain is consistent with LCH-ND as an active demyelinating process arising from a mutated hematopoietic precursor from which LCH lesion CD207+ cells are also derived. Therapy directed against myeloid precursors with activated MAPK signaling may be effective for LCH-ND. Cancer 2018;124:2607-20. © 2018 American Cancer Society.

A clinically relevant orthotopic xenograft model of ependymoma that maintains the genomic signature of the primary tumor and preserves cancer stem cells in vivo

Limited availability of in vitro and in vivo model systems has hampered efforts to understand tumor biology and test novel therapies for ependymoma, the third most common malignant brain tumor that occurs in children. To develop clinically relevant animal models of ependymoma, we directly injected a fresh surgical specimen from a 9-year-old patient into the right cerebrum of RAG2/severe complex immune deficiency (SCID) mice. All five mice receiving the initial transplantation of the patient tumor developed intracerebral xenografts, which have since been serially subtransplanted in vivo in mouse brains for 4 generations and can be cryopreserved for long-term maintenance of tumorigenicity. The xenograft tumors shared nearly identical histopathological features with the original tumors, harbored 8 structural chromosomal abnormalities as detected with spectral karyotyping, maintained gene expression profiles resembling that of the original patient tumor with the preservation of multiple key genetic abnormalities commonly found in human ependymomas, and contained a small population (<2.2%) of CD133(+) stem cells that can form neurospheres and display multipotent capabilities in vitro. The permanent cell line (BXD-1425EPN), which was derived from a passage II xenograft tumor and has been passaged in vitro more than 70 times, expressed similar differentiation markers of the xenograft tumors, maintained identical chromosomal abnormalities, and formed tumors in the brains of SCID mice. In conclusion, direct injection of primary ependymoma tumor cells played an important role in the generation of a clinically relevant mouse model IC-1425EPN and a novel cell line, BXD-1425EPN. This cell line and model will facilitate the biological studies and preclinical drug screenings for pediatric ependymomas.

Neurodegenerative central nervous system Langerhans cell histiocytosis and coincident hydrocephalus treated with vincristine/cytosine arabinoside

BACKGROUND

Central nervous system (CNS) complications of Langerhans cell histiocytosis (LCH) include mass lesions and a neurodegenerative (ND) syndrome with ataxia, dysarthria, dysmetria, learning and behavior difficulties and/or characteristic changes on brain MRIs. Hydrocephalus has rarely been reported in LCH. LCH lesions of the orbit, mastoid and temporal bones ("CNS-Risk" lesions) and diabetes insipidus predispose patients to ND-CNS-LCH. Treatment options have been limited and only a case series using trans-retinoic acid (ATRA) and intravenous immunoglobulin (IVIG) have been published.

METHODS

We have used cytosine arabinoside (ARA-C) with or without vincristine to treat eight patients with ND-CNS LCH.

PATIENTS

Seven male children and one young adult male with clinical and radiologic ND-CNS-LCH were treated with a regimen of vincristine 1.5 mg/m(2) on day 1 and ARA-C 100 mg/m(2) daily for 5 days or ARA-C alone monthly for 4-19 months. Seven patients were evaluated with an ataxia rating scale (ARS) and all with serial MRIs of the brain.

RESULTS

Five of seven patients had decreases in their ARS scores and/or decreased T2 hyperintense lesions on MRI images. Grade 2 neutropenia was the most frequent adverse event. Vincristine-associated neuropathy occurred in two patients. Hydrocephalus caused symptoms and signs that confounded the diagnosis and management of ND-CNS-LCH in all four patients affected with both.

CONCLUSIONS

Subtle changes in neurologic function may be complicated by hydrocephalus. Vcr/ARA-C or ARA-C were an effective therapies for some ND-CNS LCH patients. A clinical trial using this and possibly other modalities such as IVIG or ATRA should be done.

Disrupted nitric oxide signaling due to GUCY1A3 mutations increases risk for moyamoya disease, achalasia and hypertension

Moyamoya disease (MMD) is a progressive vasculopathy characterized by occlusion of the terminal portion of the internal carotid arteries and its branches, and the formation of compensatory moyamoya collateral vessels. Homozygous mutations in GUCY1A3 have been reported as a cause of MMD and achalasia. Probands (n = 96) from unrelated families underwent sequencing of GUCY1A3. Functional studies were performed to confirm the pathogenicity of identified GUCY1A3 variants. Two affected individuals from the unrelated families were found to have compound heterozygous mutations in GUCY1A3. MM041 was diagnosed with achalasia at 4 years of age, hypertension and MMD at 18 years of age. MM149 was diagnosed with MMD and hypertension at the age of 20 months. Both individuals carry one allele that is predicted to lead to haploinsufficiency and a second allele that is predicted to produce a mutated protein. Biochemical studies of one of these alleles, GUCY1A3 Cys517Tyr, showed that the mutant protein (a subunit of soluble guanylate cyclase) has a significantly blunted signaling response with exposure to nitric oxide (NO). GUCY1A3 missense and haploinsufficiency mutations disrupt NO signaling leading to MMD and hypertension, with or without achalasia.

Central nervous system atypical teratoid/rhabdoid tumors of infancy and childhood

In 1987, a distinctive brain tumor arising in young children was first described. This tumor contained neuroepithelial, peripheral epithelial, and mesenchymal elements, but lacked divergent tissue differentiation characteristic of malignant teratomas. It was originally designated as atypical teratoid tumor, but because of the prominent rhabdoid component, the tumor designation was modified to atypical teratoid/rhabdoid tumors (AT/RT) of infancy and childhood. AT/RTs occur most commonly in infants under 2 years of age, often have central nervous system (CNS) dissemination, do not respond to therapy, and typically are fatal within 1 year. Most are located in the cerebellum (65%), but they may arise at any CNS site. Histologically, various patterns can be present within the same tumor, but they all have a population of rhabdoid cells, and 70% contain fields typical of a primitive neuroectodermal tumor (PNET/medulloblastoma). Less frequently, malignant mesenchymal tissue and/or an epithelial component are found. Necrosis and brisk mitotic activity are common. The immunocytochemical profile is complex, but germ cell markers are consistently negative. Ultrastructural features vary and depend on the site sampled, but whorled bundles of cytoplasmic intermediate filaments are a distinctive finding in cells of the rhabdoid component. The authors report 4 AT/RTs (2 males, 2 females, age range 6 months to 4 1/2 years, 3 cerebellar, 1 cerebral). All cases showed a variety of histologic patterns with necrosis. Typical rhabdoid cells, PNET areas, undifferentiated bland large cell regions, dense connective tissue, and solid clusters of epithelial cells were present. Immunocytochemistry showed strong vimentin reactivity, whereas epithelial membrane antigen, cytokeratin, glial fibrillary acidic protein, S-100 protein, desmin, and smooth muscle actin were present to a lesser extent in most cases. Germ cell markers were negative. Ultrastructurally, many cells contained aggregates of cytoplasmic intermediate filaments, and some cells had a basal lamina on one aspect. Cells with interdigitating cytoplasmic borders were seen and rare cells had microtubules. Cytogenetic studies were normal in 2 cases. Follow-up has shown that 3 children have died of disease (< 1 year after diagnosis) and 1 child is alive with disease (18 months after diagnosis). Separation of AT/RT from PNET based on histopathologic and biologic evaluation is important, because AT/RTs are aggressive tumors with a dismal prognosis and currently there is no effective treatment. Neither clinical signs and symptoms nor radiologic features will distinguish AT/RTs from PNETs.

A pilot study of risk-adapted radiotherapy and chemotherapy in patients with supratentorial PNET

We undertook this study to estimate the event-free survival (EFS) of patients with newly diagnosed supratentorial primitive neuroectodermal tumor (SPNET) treated with risk-adapted craniospinal irradiation (CSI) with additional radiation to the primary tumor site and subsequent high-dose chemotherapy supported by stem cell rescue. Between 1996 and 2003, 16 patients with SPNET were enrolled. High-risk (HR) disease was differentiated from average-risk (AR) disease by the presence of residual tumor (M(0) and tumor size > 1.5 cm(2)) or disseminated disease in the neuraxis (M(1)-M(3)). Patients received risk-adapted CSI: those with AR disease received 23.4 Gy; those with HR disease, 36-39.6 Gy. The tumor bed received a total of 55.8 Gy. Subsequently, all patients received four cycles of high-dose cyclophosphamide, cisplatin, and vincristine with stem cell support. The median age at diagnosis was 7.9 years; eight patients were female. Seven patients had pineal PNET. Twelve patients are alive at a median follow-up of 5.4 years. The 5-year EFS and overall survival (OS) estimates for all patients were 68% +/- 14% and 73% +/- 13%. The 5-year EFS and OS estimates were 75% +/- 17% and 88% +/- 13%, respectively, for the eight patients with AR disease and 60% +/- 19% and 58% +/- 19%, respectively, for the eight with HR disease. No deaths were due to toxicity. High-dose cyclophosphamide-based chemotherapy with stem cell support after risk-adapted CSI results in excellent EFS estimates for patients with newly diagnosed AR SPNET. Further, this chemotherapy allows for a reduction in the dose of CSI used to treat AR SPNET without compromising EFS.

Implications of tumor location on subtypes of medulloblastoma

BACKGROUND

Medulloblastoma (MB) comprises of four molecular subtypes, Sonic hedgehog (SHH), Wingless (WNT), Groups 3 and 4. WNT-subtype MBs were found to arise from midline of the brainstem occupying the fourth ventricle while SHH-subtype occupied the cerebellar hemisphere in a small subset of patients.

PROCEDURE

We tested this hypothesis in a large cohort of pediatric MBs comprising of all four molecular subtypes.

RESULTS

We validated in the first comprehensive analysis of tumor location of 60 human MBs representative of the four molecular subtypes, that hemispheric tumors are significantly associated with SHH-subtype MBs while midline tumors with WNT-subtype, Group 3 and 4 MBs (P < 0.001). Nearly half of SHH-subtype MBs were midline.

CONCLUSIONS

Tumor location should not be generalized to MB subtypes. SHH-subtype MBs are not exclusively hemispheric and hemispheric MBs are not always SHH-activated. It is imperative to identify subtypes in conjunction with tumor location when exploring currently available targeted therapy.

Plasma and cerebrospinal fluid pharmacokinetics of pemetrexed after intravenous administration in non-human primates

PURPOSE

Pemetrexed, a multi-targeted antifolate that disrupts synthesis of both purines and pyrimidines, is approved for use in malignant pleural mesothelioma and non-small cell lung cancer. Pemetrexed is currently being evaluated for anti-tumor activity in a variety of solid and central nervous system tumors. We studied the plasma and cerebrospinal fluid (CSF) pharmacokinetics of pemetrexed in a non-human primate model that is highly predictive of human CSF penetration.

METHODS

Pemetrexed, 20 mg/kg (400 mg/m2), was administered intravenously to four non-human primates. Serial blood samples were obtained from all animals and serial CSF samples were obtained from three animals. Plasma and CSF concentrations of pemetrexed were measured using LC/MS/MS and the resulting concentration versus time data were evaluated using model independent and dependent methods.

RESULTS

Pemetrexed disappearance from plasma was best described by a two compartment model with a mean distribution half-life of 13.8 +/- 3.2 min and an elimination half-life of 70.0 +/- 16.0 min. The volume of distribution of and the clearance from the central compartment were 0.066 +/- 0.017 l/kg and 3.6 +/- 0.6 ml/min/kg, respectively. Peak CSF concentrations occurred 40-71 min after the start of the infusion with an average of 0.26 +/- 0.15 microM.

CONCLUSION

The CSF penetration of pemetrexed was less than 2% (range 0.33-1.58%), suggesting that it should be used in conjunction with other CNS preventive strategies when used in the treatment of malignancies with a predilection for CNS or leptomeningeal metastases.

Pharmacokinetics and cerebrospinal fluid penetration of phenylacetate and phenylbutyrate in the nonhuman primate

INTRODUCTION

Phenylbutyrate (PB) and its metabolite phenylacetate (PA) demonstrate anticancer activity in vitro through promotion of cell differentiation, induction of apoptosis through the p21 pathway, inhibition of histone deacetylase, and in the case of PB, direct cytotoxicity. We studied the pharmacokinetics, metabolism, and cerebrospinal fluid (CSF) penetration of PA and PB after intravenous (i.v.) administration in the nonhuman primate.

METHODS

Three animals received 85 mg/kg PA and 130 mg/kg PB as a 30-min infusion. Blood and CSF samples were obtained at 15, 30, 35, 45, 60 or 75 min, and at 1.5, 2.5, 3.5, 5.5, 6.5, 8.5, 10.5 and 24.5 h after the start of the infusion. Plasma was separated immediately, and plasma and CSF were frozen until HPLC analysis was performed.

RESULTS

After i.v. PA administration, the plasma area under the concentration-time curve (AUC) of PA (median +/- SD) was 82 +/- 16 mg/ml.min, the CSF AUC was 24 +/- 7 mg/ml.min, clearance (Cl) was 1 +/- 0.3 ml/min per kg, and the AUCCSF:AUCplasma ratio was 28 +/- 19%. After i.v. PB administration, the plasma PB AUC was 19 +/- 3 mg/ml.min, the CSF PB AUC was 8 +/- 11 mg/ml.min, the PB Cl was 7 +/- 1 ml/min per kg, and the AUCCSF:AUCplasma ratio was 41 +/- 47%. The PA plasma AUC after i.v. PB administration was 50 +/- 9 mg/ml.min, the CSF AUC was 31 +/- 24 mg/ml.min, and the AUCCSF:AUCplasma ratio was 53 +/- 46%.

CONCLUSIONS

These data indicate that PA and PB penetrate well into the CSF after i.v. administration. There may be an advantage to administration of PB over PA, since the administration of PB results in significant exposure to both active compounds. Clinical trials to evaluate the activity of PA and PB in pediatric central nervous system tumors are in progress.

Plasma and cerebrospinal fluid pharmacokinetics of depsipeptide (FR901228) in nonhuman primates

PURPOSE

Acetylation of histones by histone acetyl transferases (HATs) leads to transcriptional activation, while histone deacetylase (HDAC) activity leads to transcriptional repression. Abnormalities of histone acetylation are associated with the malignant phenotype. Depsipeptide (FR901228) inhibits HDAC and has shown anticancer activity in preclinical models. We studied the plasma and cerebrospinal fluid (CSF) pharmacokinetics of depsipeptide in a nonhuman primate model that is highly predictive of human CSF penetration.

DESIGN

Depsipeptide was administered intravenously at a dose of 10 mg/m(2) over 4 h to three different animals. Serial blood samples were obtained from all animals and serial CSF samples were obtained from two animals. Plasma and CSF concentrations of depsipeptide were measured using liquid chromatography/tandem mass spectrometry. Concentration-versus-time data were modeled using model-independent and model-dependent methods.

RESULTS

The peak plasma concentration (median+/-SD) was 245+/-50 n M and occurred within the first 2 h of the infusion. The terminal half-life was 205+/-315 min, the AUC extrapolated to infinity was 50+/-15 micro M.min, and the total body clearance was 350+/-65 ml/min/m(2). In the two animals that had CSF sampling performed, the CSF peak concentration was 3.6 n M in one animal and 2.3 n M in the other, and the CSF half-lives were 250 and 325 min. The CSF penetration of depsipeptide (AUC(CSF):AUC(plasma)) was 2% in each animal. Observed changes included anorexia, fatigue, elevation of creatine phosphokinase (CPK) enzyme levels (muscle fraction), and transient early leukopenia. All animals recovered without sequelae.

CONCLUSIONS

Although the CSF exposure to depsipeptide after intravenous administration was only 2%, CSF concentrations approached the IC(50) of depsipeptide in vitro for some tumors. Systemic administration of this agent may be useful for the treatment of leptomeningeal tumors.

Long-term outcome of centrally located low-grade glioma in children

BACKGROUND

Optimal management of children with centrally located low-grade glioma (LGG) is unclear. Initial interventions in most children are chemotherapy in younger and radiation therapy (RT) in older children. A better understanding of the inherent risk factors along with the effects of interventions on long-term outcome can lead to reassessment of the current approaches to minimize long-term morbidity.

METHODS

To reassess the current treatment strategies of centrally located LGG, we compared the long-term survival and morbidity of different treatment regimens. Medical records of patients primarily treated at Texas Children's Cancer and Hematology Centers between 1987 and 2008 were reviewed.

RESULTS

Forty-seven patients with a median follow-up of 79 months were included in the analysis. The 5-year overall survival and progression-free survival (PFS) for all patients were 96% and 53%, respectively. The 5-year PFS for those treated initially with RT (12 patients; median age, 11 years [range, 3-15 years]) and with chemotherapy (28 patients; median age, 2 years [range 0-8 years]) were 76% and 37%, respectively (log-rank test P = .02). Among children who progressed after chemotherapy, the 5-year PFS after salvage RT was 55%. Patients diagnosed at a younger age (<5 years) were more likely to experience endocrine abnormalities (Fisher exact test; P<.00001).

CONCLUSIONS

Effective and durable tumor control was obtained with RT as initial treatment. In younger patients, chemotherapy can delay the use of RT; however, frequent progression and long-term morbidity are common. More effective and less toxic therapies are required in these patients, the majority of whom are long-term survivors.

Plasma and cerebrospinal fluid pharmacokinetics of gemcitabine after intravenous administration in nonhuman primates

PURPOSE

Gemcitabine (dFdC) is a difluorine-substituted deoxycytidine analogue that has demonstrated antitumor activity against both leukemias and solid tumors. Pharmacokinetic studies of gemcitabine have been performed in both adults and children but to date there have been no detailed studies of its penetration into cerebrospinal fluid (CSF). The current study was performed in nonhuman primates to determine the plasma and CSF pharmacokinetics of gemcitabine and its inactive metabolite, difluorodeoxyuridine (dFdU) following i.v. administration.

METHODS

Gemcitabine, 200 mg/kg, was administered i.v. over 45 min to four nonhuman primates. Serial plasma and CSF samples were obtained prior to, during, and after completion of the infusion for determination of gemcitabine and dFdU concentrations. Gemcitabine and dFdU concentrations were measured using high-performance liquid chromatography (HPLC) and modeled with model-dependent and model-independent methods.

RESULTS

Plasma elimination was rapid with a mean t1/2 of 8 +/- 4 min (mean +/- SD) for gemcitabine and 83 +/- 8 min for dFdU. Gemcitabine total body clearance (ClTB) was 177 +/- 40 ml/min per kg and the Vdss was 5.5 +/- 1.0 l/kg. The maximum concentrations (Cmax) and areas under the time concentration curves (AUC) for gemcitabine and dFdU in plasma were 194 +/- 64 microM and 63.8 +/- 14.6 microM.h, and 783 +/- 99 microM and 1725 +/- 186 microM.h, respectively. The peak CSF concentrations of gemcitabine and dFdU were 2.5 +/- 1.4 microM and 32 +/- 41 microM, respectively. The mean CSF:plasma ratio was 6.7% for gemcitabine and 23.8% for dFdU.

CONCLUSIONS

There is only modest penetration of gemcitabine into the CSF after i.v. administration. The relatively low CSF exposure to gemcitabine after i.v. administration suggests that systemic administration of this agent is not optimal for the treatment of overt leptomeningeal disease. However, the clinical spectrum of antitumor activity and lack of neurotoxicity after systemic administration of gemcitabine make this agent an excellent candidate for further studies to assess the safety and feasibility of intrathecal administration.

Plasma and CSF pharmacokinetics of ganciclovir in nonhuman primates

PURPOSE

The antiviral nucleoside analogue ganciclovir is a potent inhibitor of replication in herpes viruses and is effective against cytomegalovirus infections in immunocompromised patients. Ganciclovir is also used in cancer gene therapy studies that utilize the herpes simplex virus thymidine kinase gene (HSV-TK). The pharmacokinetics of ganciclovir in adults and children have been described previously but there are no detailed studies of the CNS pharmacology of ganciclovir. We studied the pharmacokinetics of ganciclovir in plasma and CSF in a nonhuman primate model that is highly predictive of the CSF penetration of drugs in humans.

METHODS

Ganciclovir, 10 mg/kg i.v., was administered over 30 min to three animals. Ganciclovir concentrations in plasma and CSF were measured using reverse-phase HPLC.

RESULTS

Peak plasma ganciclovir concentrations ranged from 18.3 to 20.0 microg/ml and the mean plasma AUC was 1075+/-202 microg/ml x min. Disappearance of ganciclovir from the plasma was biexponential with a distribution half-life (t(1/2)alpha) of 18+/-7 min and an elimination half-life (t(1/2)beta) of 109+/-7 min. Total body clearance (ClTB) was 9.4+/-1.6 ml/min/kg. The mean CSF ganciclovir AUC was 168+/-83 microg/ml x min and the mean peak CSF concentration was 0.7+/-0.3 microg/ml. The ratio of the AUCs in CSF and plasma was 15.5+/-7.1%.

CONCLUSIONS

Ganciclovir penetrates into the CSF following i.v. administration. This finding will be useful in the design of gene therapy trials involving the HSV-TK gene followed by treatment with ganciclovir in CNS or leptomeningeal tumors.

Primary malignant rhabdoid tumor of the central nervous system

Since the initial description of malignant rhabdoid tumor (MRT) of the kidney by Beckwith in 1978, MRTs have been established as a distinct clinicopathologic entity lacking nephrogenic and myogenic differentiation. MRTs are highly aggressive neoplasms with characteristic histopathologic, immunocytochemical, and ultrastructural features. Many reports have appeared documenting primary extrarenal rhabdoid tumors (ERRTs) occurring at diverse sites, including infratentorial and supratentorial compartments of the central nervous system (CNS). The authors report 2 cases of primary CNS-MRT in young male children (6.5 and 7 years of age) and review the literature on CNS-MRTs. Neuroimaging studies showed an inhomogeneous parasagittal mass in the left anterior parietal region involving the motor strip and attached to the lateral aspect of the superior sagittal sinus in one case, and a right parietal parasagittal tumor with a cystic component in the other case. Metastatic workup, including abdominal CT, was negative in both cases. Histologic examination of the resected tumors showed irregular clusters and nests of cells with variable desmoplasia in both cases. Large areas of tumor necrosis and apoptotic tumor cells were present. Prominent eosinophilic cytoplasmic inclusions and eccentric, indented nuclei with conspicuous nucleoli characterized many of the tumor cells. Diffuse strong vimentin reactivity and focal strong reaction for epithelial membrane antigen (EMA) were demonstrated. Cytogenetic analyses reported a normal male karyotype in one case and an abnormal male karyotype with loss of both normal copies of chromosome 22 and gain of one structurally rearranged chromosome 22 in the other case. Ultrastructural examination displayed tumor cells with avoid to indented nuclei, marginated chromatin, and prominent nucleoli. Intercellular junctions were not found. Masses of cytoplasmic intermediate filaments in a characteristic whorled configuration were present. CNS-MRTs are consistently vimentin positive (100%) and usually EMA positive (90%). Glial fibrillary acidic protein, neuron-specific enolase, and S-100 protein are variably expressed. Markers for myogenous differentiation are invariably absent. Ultrastructural characteristics include aggregates of intermediate filaments. Monosomy 22 occurs in some CNS rhabdoid tumors, while most renal rhabdoid tumors are cytogenetically normal with only isolated cases having del(13q), del(11p), del(22)(q11), and unbalanced reciprocal translocation involving chromosomes 8 and 22. The prognosis for CNS rhabdoid tumors is dismal and almost two-thirds of patients are dead of disease shortly after diagnosis; one-third have been reported to be alive with disease, but have been followed for only short periods; and a single patient is reported to be free of disease at 5 years.

Plasma and cerebrospinal fluid pharmacokinetics of clofarabine in nonhuman primates

INTRODUCTION

Clofarabine (2-chloro-2'fluoro-2'-deoxy-9-beta-d-arabinofuranosyladenine) is a purine nucleoside analogue that is active in the treatment of acute leukemia. We studied the pharmacokinetics and cerebrospinal fluid penetration of clofarabine in a nonhuman primate model.

METHODS

A dose of 2.3 mg/kg of clofarabine was given i.v. over 2 hours to each of four animals. Plasma and cerebrospinal fluid (CSF) samples were obtained at specified intervals and the clofarabine concentration determined by reverse-phase high-pressure liquid chromatography with mass spectroscopy.

RESULTS

The median clofarabine clearance was 17 mL/min/kg (range, 15-20), the median plasma area under the concentration-time curve was 452 mumol/L minutes (range, 380-487), and the median terminal half-life was 105 minutes (range, 78-138). Concentrations of clofarabine in CSF could not be modeled reliably because the terminal rate constant was not well defined. The median CSF penetration was 5% (range, 3-26%).

CONCLUSION

Clofarabine penetrates into the CSF only modestly, but the concentrations obtained may approach those that are cytotoxic in vitro. Evaluation of the contribution of clofarabine to central nervous system preventive therapy should be considered in future studies.

Therapeutic implications of CD1d expression and tumor-infiltrating macrophages in pediatric medulloblastomas

Immunobiology of medulloblastoma (MB), the most common malignant brain tumor in children, is poorly understood. Although tumor cells in some MBs were recently shown to express CD1d and be susceptible to Vα24-invariant natural killer T (NKT)-cell cytotoxicity, the clinical relevance of CD1d expression in MB patients remains unknown. We investigated the expression of CD1d in pediatric MBs and correlated with molecular and clinical characteristics. Specifically, we explored if NKT cell therapy can be targeted at a subset of pediatric MBs with poorer prognosis. Particularly, infantile MBs have a worse outcome because radiotherapy is delayed to avoid neurocognitive sequelae. Immunohistochemistry for CD1d was performed on a screening set of 38 primary pediatric MBs. Gene expression of the membrane form of M2 macrophage marker, CD163, was studied in an expanded cohort of 60 tumors. Outcome data was collected prospectively. Thirteen of 38 MBs (34.2 %) expressed CD1d on immunohistochemistry. CD1d was expressed mainly on MB tumor cells, and on some tumor-associated macrophages. Majority (18/22, 82 %) of non sonic-hedgehog/Wingless-activated MBs (group 3 and 4) were CD1d-negative (p = 0.05). A subset of infantile MBs (4/9, 44.4 %) expressed CD1d. Macrophages infiltrating MB expressed CD163 apart from CD1d. Molecular subtypes demonstrated statistical differences in CD163 expression, SHH-tumors were the most enriched (p = 0.006). Molecular and clinical subtypes of pediatric MB exhibit distinct differences in CD1d expression, which have important therapeutic implications. High CD1d expression in infantile MBs offers potential new immunotherapeutic treatment with NKT cell therapy in infants, where treatment is suboptimal due delayed radiotherapy.

Anaplastic ganglioglioma arising from a Lhermitte-Duclos-like lesion. Case report

The authors report the case of a 7-year-old boy with a history of developmental delay who presented with aggressive behavior. A magnetic resonance (MR) image showed a mass lesion originating from the cerebellar vermis with an atypical folial pattern and contrast enhancement. Histologically, the subtotally resected specimen consisted mostly of neuropil with nodular foci of ganglion cells. Lhermitte-Duclos disease (LDD) was diagnosed in the patient. A retrospective review of the tissue sections showed a nidus of associated astrocytic proliferation, suggesting a diagnosis of ganglioglioma. Five years later, the patient experienced an altered mental state and a facial droop. An MR image revealed a cerebellar mass with cystic areas and an enhancing nodule. The resected tissue specimen consisted primarily of a mixed proliferation of glial and ganglion cells consistent with a ganglioglioma. Two years later, a third craniectomy was performed in the patient for worsening headache and ataxia. Histologically, the tumor showed progressive anaplasia and was most accurately classified as an anaplastic ganglioglioma. Immunohistochemically, most of the tumor cells were immunoreactive for anti-phospho-mammalian target of rapamycin (mTOR) and phospho-S6 ribosomal protein antibodies. In contrast, the subpopulation of neoplastic ganglion cells in the tissue, particularly from the first surgery, did not express phosphatase and tensin homolog deleted from chromosome 10 (PTEN). This immunohistochemical pattern suggests that the large dysplastic ganglion cells (the gangliocytomatous component) forming the greater part of the lesion were associated with activation of the phosphatidylinositol 3-kinase-PTEN/Akt/mTOR signaling pathway, a feature previously reported in LDD. This case represents the first report of an anaplastic ganglioglioma arising in an LDD-like lesion.

Hypothyroidism after craniospinal irradiation with proton or photon therapy in patients with medulloblastoma

BACKGROUND

Craniospinal irradiation (CSI) often results in endocrine deficiencies in children with medulloblastoma due to irradiation of the hypothalamic-pituitary axis (HPA) or the thyroid gland. CSI with Proton radiation therapy (PRT) has the potential to decrease the risk of hypothyroidism by reduction in radiation dose to these organs. This study compares the risk for hypothyroidism in patients with medulloblastoma treated with Photon radiation therapy (XRT) or PRT.

METHODS

The records of patients with medulloblastoma diagnosed at a single institution between 1997 and 2014 who received CSI were, retrospectively, reviewed. Ninety-five patients (54 XRT and 41 PRT) who had baseline and yearly follow-up thyroid studies were included. We used interval censored Cox regression to calculate hazard ratios of developing any, primary, and central hypothyroidism.

RESULTS

With a median time to last thyroid studies post radiation of 3.8 years in PRT and 9.6 years in XRT, 33/95 (34.7%) patients developed hypothyroidism (median time to hypothyroidism: 2.6 years). Hypothyroidism developed in 25/54 (46.3%) who received XRT vs. 8/41 (19%) in the PRT group (HR =1.85, p = .14). Primary hypothyroidism developed in 15/95 (15.8%) patients: 12/54 (22.2%) after XRT and 3/41 (7.3%) after PRT (HR =2.1, p = .27). Central hypothyroidism developed in 17/95 (18.0%) patients: 13/54 (24.0%) after XRT and 4/41 (9.8%) after PRT (HR =2.16, p = .18).

CONCLUSIONS

The use of PRT in patients with medulloblastoma was associated with numerically lower but not significantly lower risk of hypothyroidism. Further studies including larger numbers and longer follow up must be performed to assess whether lower radiation doses achieved with PRT show statistically significant differences.

Plasma and cerebrospinal fluid pharmacokinetic study of BNP1350 in nonhuman primates

PURPOSE

BNP1350 (7-[(2-trimethylsilyl)ethyl]-20(S)-camptothecin, karenitecin), a highly lipophilic camptothecin, a high percentage of which is maintained in the active lactone form under physiologic conditions, has recently entered clinical trials in adults and children. BNP1350 has shown significant preclinical antitumor activity against a wide variety of adult and pediatric tumor cell lines. This study was undertaken to define the pharmacokinetics of BNP1350 in both plasma and cerebrospinal fluid (CSF) in a nonhuman primate model.

METHODS

Four nonhuman primates with indwelling Ommaya reservoirs received BNP1350, 0.1 mg/kg i.v, administered as a 60-min infusion. Frequent plasma and CSF samples were obtained for quantitation of BNP1350 concentrations using reverse-phase high-pressure liquid chromatography (HPLC).

RESULTS

Disappearance of the lactone form from the plasma was biexponential with a mean distribution half-life of 57.5 min (CV +/-33%) and an elimination half-life of 457 min (CV +/-24%). The volume of distribution for the central compartment was 1.36 l/kg (CV +/-27%) and clearance from the central compartment was 10.6 ml/kg per minute (CV +/-28%). The peripheral compartment volume of distribution was 1.96 l/kg (CV +/-8.4%). Peak CSF lactone concentration, which occurred at 12 to 25 min after the end of the infusion, was 0.33 n M (CV +/-71%).

CONCLUSIONS

The ratio of the CSF AUC to the plasma AUC was less than 5% (range 0.4% to 3.0%), similar to other highly protein-bound topoisomerase inhibitors such as 9-aminocamptothecin and SN-38 (the active metabolite of irinotecan).

Plasma and cerebrospinal fluid pharmacokinetics of SU5416 after intravenous administration in nonhuman primates

PURPOSE

SU5416 is a small, lipophilic synthetic molecule that selectively inhibits the tyrosine kinase activity of the VEGF receptor Flk-1/KDR. The role of this agent in brain tumors is currently being investigated. Pharmacokinetic studies of SU5416 have been performed in humans; however, there have been no studies of its penetration in the cerebrospinal fluid (CSF). We studied the pharmacokinetics of SU5416 in plasma and CSF after intravenous (i.v.) administration using a nonhuman primate model that is highly predictive of the CSF penetration in humans.

EXPERIMENTAL DESIGN

SU5416 (85 mg/m(2), about 3.8 mg/kg) was administered i.v. over 20 min to four nonhuman primates. Serial plasma and CSF samples were obtained prior to, during, and after completion of the infusion for determination of SU5416 concentrations. SU5416 was measured in plasma and CSF using high-performance liquid chromatography (HPLC). Concentration-versus-time data were modeled using model-independent and model-dependent methods.

RESULTS

Peak plasma concentrations ranged from 6.3 to 14.5 microM and the mean plasma AUC was 620+/-180 microM.min. Disappearance of SU5416 from the plasma was best described by a one-compartment model with a half-life of 39+/-2.9 min. The volume of distribution was 36+/-11 l/m(2) and the clearance was 0.62+/-0.2 l/min per m(2). SU4516 was not quantifiable in the CSF.

CONCLUSIONS

There is minimal penetration of SU5416 into the CSF after i.v. administration. The very low CNS exposure to SU5416 after i.v. dosing suggests that this agent is not optimal for the treatment of leptomeningeal tumors.

Plasma and cerebrospinal fluid pharmacokinetics of nelarabine in nonhuman primates

INTRODUCTION

Nelarabine is a water-soluble prodrug of the cytotoxic deoxyguanosine analog ara-G, to which it is rapidly converted in vivo by adenosine deaminase. Nelarabine has shown activity in the treatment of T-cell malignancies, especially T-cell acute lymphoblastic leukemia. Preliminary data suggested that nelarabine might penetrate into the CSF. We therefore studied the CSF penetration of nelarabine and ara-G in a nonhuman primate model that has been highly predictive of anticancer drug distribution in humans.

METHODS

Nelarabine (35 mg/kg, approximately 700 mg/m2) was administered over 1 h through a surgically implanted central venous catheter to four nonhuman primates. Blood (four animals) and ventricular CSF (three animals) samples were obtained at intervals for 24 h for determination of nelarabine concentrations, which were measured by HPLC-mass spectrometry.

RESULTS

The nelarabine plasma AUC (median+/-s.d.) was 2,820+/-1,140 microM min and the ara-G plasma AUC was 20,000+/-8,100 microM min. The terminal half-life of nelarabine in plasma was 25+/-5.2 min and clearance was 42+/-61 ml/min/kg. The terminal half-life of ara-G in plasma was 182+/-45 min. In CSF the terminal half-life of nelarabine was 77+/-28 min and of ara-G was 232+/-79 min. The AUCcsf:AUCplasma was 29+/-11% for nelarabine and 23+/-12% for ara-G.

CONCLUSION

The excellent CSF penetration of nelarabine and ara-G supports further study of the contribution of nelarabine to the prevention and treatment of CNS leukemia.

Simplifying soft tissue closure of the large meningomyelocele defect: A technical note

The surgical management of large neural tube defects not amenable to primary closure poses a significant challenge. As a result, large residual skin defects often prompt excessively aggressive primary closure, complicated skin incisions, or flap advancements. However, our experience with the purse-string closure of a large meningomyelocele skin defect demonstrates that this technique can effectively provide coverage of very large meningomyelocele defects with minimal residual deformity. Here, we discuss the successful coverage of a large 5 x 5 cm meningomyelocele skin wound via staged purse-string closure spaced 2 weeks apart.