To determine whether temozolomide is an active agent in the treatment of children with high-grade astrocytomas and whether survival is influenced by the expression of the O6-methylguanine-methyltransferase gene (MGMT) in these patients. In the Children's Oncology Group study ACNS0126, 107 patients with a diagnosis of anaplastic astrocytoma (AA), glioblastoma multiforme (GBM), or gliosarcoma were enrolled. All patients underwent concomitant chemoradiotherapy with temozolomide, followed by adjuvant chemotherapy with temozolomide. The outcomes were compared with those of children treated in Children's Cancer Group (CCG) study CCG-945. Formalin-fixed, paraffin-embedded tumor tissue was available in 71 cases for immunohistochemical analysis of MGMT expression. Ninety patients were deemed eligible, 31 with AA, 55 with GBM, and 4 with other eligible diagnoses. The 3-year event-free survival (EFS) and overall survival (OS) rates were 11 ± 3% and 22 ± 5%, respectively. There was no evidence that temozolomide given during radiation therapy and as adjuvant therapy resulted in improved EFS compared with that found in CCG-945 (p = 0.98). The 3-year EFS rate for AA was 13 ± 6% in ACNS0126 compared with 22 ± 5.5% in CCG-945 (p = 0.95). The 3-year EFS rate for GBM was 7 ± 4% in ACNS0126 compared with 15 ± 5% in CCG-945 (p = 0.77). The 2-year EFS rate was 17 ± 5% among patients without MGMT overexpression and 5 ± 4% among those with MGMT overexpression (p = 0.045). Temozolomide failed to improve outcome in children with high-grade astrocytomas. MGMT overexpression was adversely associated with survival.

Childhood atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system (CNS) is a recently described entity. Diagnosis is based on distinctive light microscopy and immunohistochemical findings, coupled with molecular genetic analysis. Most AT/RTs demonstrate monosomy 22 or deletions of chromosome band 22q11 with alterations of the hSNF5/INI1 gene. The tumor's incidence is still undefined, but it may comprise as high as 1 in 4 primitive CNS tumors in infants. Treatment is far from optimal, but there are occasional long-term survivors, especially among older children. Therapeutic approached have included surgery, chemotherapy, and radiotherapy. Prospective clinical trials are needed for children with AT/RTs.

An open-label phase II study (ACNS0126) testing the efficacy of chemoradiotherapy with temozolomide (TMZ) followed by adjuvant TMZ was conducted by the Children's Oncology Group. During the period from July 6, 2004 through September 6, 2005, 63 children with newly diagnosed diffuse intrinsic pontine glioma (DIPG) were enrolled in the study. All patients received TMZ at a dosage of 90 mg/m(2)/day for 42 days to a dose of 59.4 Gy. Four weeks following irradiation, TMZ was given at a dosage of 200 mg/m(2)/day for 5 days every 28 days, for a total of 10 cycles. The primary objective of the statistical analysis was to determine whether the current treatment produced a 1-year event-free survival (EFS) rate higher than the historical baseline of 21.9% observed in CCG-9941. The mean 1-year EFS (± standard deviation) was 14% ± 4.5%, compared with 21.9% ± 5% for CCG-9941. The P value of the test of comparison of 1-year EFS, based on a 1-sided, 1-sample test of proportions, was .96. There was no evidence that temozolomide produced a 1-year EFS rate higher than 21.9%. The mean 1-year OS (± standard deviation) was 40% ± 6.5%, compared with 32% ± 6% for CCG-9941. The median time to death was 9.6 months. Chemoradiotherapy with TMZ followed by adjuvant TMZ is not more effective than previously reported regimens for the treatment of children with DIPG.

The majority of infants treated for medulloblastoma experienced disease progression during initial chemotherapy. However, more than half of these patients can be cured with salvage radiation therapy, regardless of M stage. The presence of metastatic disease did not increase the risk of dying from medulloblastoma. All patients treated in this fashion have significant neuropsychologic deficits. Our experience demonstrates that medulloblastoma in infancy is a curable disease, albeit at a significant cost.

The overall survival in this series of pediatric low-grade astrocytomas is excellent. Age at diagnosis and tumor location, but not histology, had a significant impact on PFS. Efforts to improve treatment outcome should focus on young patients (< 5 years) and on those with central midline tumors. The majority of patients with completely resected hemispheric tumors were monitored without further therapy, which supports attempted GTR of cerebral and cerebellar hemisphere low-grade astrocytoma.

Adverse outcome in childhood intracranial ependymoma is related to age (3 years or younger), histology (grade 3), and degree of surgical resection (less than GTR). New approaches, particularly for local tumor control in younger patients, are needed to improve survival.

The disposition of the synthetic corticosteroids, dexamethasone and prednisolone, in CSF was evaluated following bolus intravenous (IV) and intrathecal (IT) injection in a nonhuman primate model. Steroid concentration in plasma and CSF was measured with a radioimmunoassay following celite column chromatography. The CSF to plasma ratios of dexamethasone and prednisolone following IV bolus administration were 0.15 +/- 0.02 and 0.08 +/- 0.03, respectively. Although peak levels of the two steroids in the CSF reached equally potent levels when administered systemically in equipotent doses, the half-life of prednisolone in the CSF was shorter. In addition, there was a significant difference in the plasma protein binding of the two steroids, which may account for the differences in their CSF pharmacokinetics. Dexamethasone was 70% protein bound over a wide concentration range, while the protein binding of prednisolone was concentration dependent, ranging from 60% at 10 mumol/L to 95% at 0.5 mumol/L and below. After the initial distribution phase in plasma, CSF concentrations of dexamethasone and prednisolone approximated free plasma concentrations, indicating that penetration into the CSF was limited primarily by protein binding. At the plasma concentrations achieved following oral administration of standard doses of prednisone in children, the prednisolone (the active metabolite) is greater than 90% protein bound. The proportionally higher free plasma levels of dexamethasone result in greater penetration into the CSF. These findings may explain the lower rates of meningeal leukemia observed in children receiving dexamethasone instead of prednisone for the treatment of acute lymphoblastic leukemia (ALL).

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