Arzu Onar

Outcome of Children With Metastatic Medulloblastoma Treated With Carboplatin During Craniospinal Radiotherapy: A Children's Oncology Group Phase I/II Study

PURPOSE We evaluated the feasibility of administering carboplatin as a radiosensitizer during craniospinal radiation therapy (CSRT) to patients with high-risk medulloblastomas (MBs) and supratentorial primitive neuroectodermal tumors, and we report the outcome in the subset with metastatic (M+) MB. PATIENTS AND METHODS After surgery, patients received 36 Gy CSRT with boosts to sites of disease. During radiation, patients received 15 to 30 doses of carboplatin (30-45 mg/m(2)/dose), along with vincristine (VCR) once per week for 6 weeks. Patients on regimen A received 6 months of maintenance chemotherapy (MC) with cyclophosphamide and VCR. Once the recommended phase II dose (RP2D) of carboplatin was determined, cisplatin was added to the MC (regimen B). RESULTS In all, 161 eligible patients (median age, 8.7 years; range, 3.1 to 21.6 years) were enrolled. Myelosuppression was dose limiting and 35 mg/m(2)/dose × 30 was determined to be the RP2D of carboplatin. Twenty-nine (36%) of 81 patients with M+ MB had diffuse anaplasia. Four patients were taken off study within 11 months of completing radiotherapy for presumed metastatic progression and are long-term survivors following palliative chemotherapy. Excluding these four patients, 5-year overall survival ± SE and progression-free survival ± SE for M+ patients treated at the RP2D on regimen A was 82% ± 9% and 71% ± 11% versus 68% ± 10% and 59% ± 10% on regimen B (P = .36). There was no difference in survival by M stage. Anaplasia was a negative predictor of outcome. CONCLUSION The use of carboplatin as a radiosensitizer is a promising strategy for patients with M+ MB. Early progression should be confirmed by biopsy.

Phase I and Pharmacokinetic Study of the Oral Farnesyltransferase Inhibitor Lonafarnib Administered Twice Daily to Pediatric Patients With Advanced Central Nervous System Tumors Using a Modified Continuous Reassessment Method: A Pediatric Brain Tumor Consortium Study

PURPOSE A dose-escalation phase I and pharmacokinetic study of the farnesyltransferase inhibitor lonafarnib (SCH66336) was conducted in children with recurrent or progressive CNS tumors. Primary objectives were to estimate the maximum-tolerated dose (MTD) and to describe the dose-limiting toxicities (DLTs) and pharmacokinetics of lonafarnib. Farnesylation inhibition of HDJ-2 in peripheral blood was also measured. PATIENTS AND METHODS Lonafarnib was administered orally twice daily at dose levels of 70, 90, 115, 150, and 200 mg/m2/dose bid. A modified continual reassessment method (CRM) was used to estimate the MTD based on actual dosages of lonafarnib administered and toxicities observed during the initial 4 weeks of treatment. RESULTS Fifty-three children with progressive or recurrent brain tumors were enrolled, with a median age of 12.2 years (range, 3.9 to 19.5 years). Dose-limiting pneumonitis or myelosuppression was observed in three of three patients at the 200 mg/m2/dose level. A relatively constant DLT rate at the 70, 90, and 115 mg/m2/dose levels resulted in a recommended phase II dose of 115 mg/m2/dose. Significant diarrhea did not occur with prophylactic loperamide. Both radiographic response (one anaplastic astrocytoma) and stable disease (one medulloblastoma, two high-grade and four low-grade gliomas, one ependymoma, and one sarcoma) were noted, and seven patients remained on treatment for 1 year or longer. CONCLUSION Although the estimated MTD by the CRM model was 98.5 mg/m2/dose, because of the relatively constant observed DLT rate at the lower four dose levels, the recommended phase II dose of lonafarnib is 115 mg/m2/dose administered twice daily by mouth with concurrent loperamide.

Health Status in Long-Term Survivors of Pediatric Craniopharyngiomas

Craniopharyngiomas are the third most common pediatric brain tumor and most common pediatric suprasellar tumor. Contemporary treatment of craniopharyngiomas uses limited surgery and radiation in an effort to minimize morbidity, but the long-term health status of patients treated in this fashion has not been well described. The purpose of this study was to analyze the health status of long-term survivors of pediatric craniopharyngioma treated primarily with radiation and conservative surgical resection. Medical records of all long-term survivors of craniopharyngioma treated at St. Jude Childrens Research Hospital and then transferred to the long-term follow-up clinic were reviewed. The initial cohort comprised 55 patients. Of these, 51 (93%) were alive at the time of this analysis. The median age at diagnosis was 7.1 years (range, 1.2-17.6 years), and 29 (57%) were male. At the time of analysis, the median survival was 7.6 years (range, 5.0-21.3 years). Diagnosis and treatment included surgical biopsy, resection (n = 50), and radiation therapy (n = 48). Only 1 patient received chemotherapy. Polyendocrinopathy was the most common morbidity, with hypothyroidism (96%), adrenocorticotropic hormone deficiency (84%), and diabetes insipidus (53%) occurring most frequently. Half of the patients were hypogonadal, and 33 (65%) were overweight or obese. The most common neurologic problems included shunt dependence (37%), seizures (28%), and headaches (39%). Psychological and educational deficits were also identified in a significant number of these individuals. Despite efforts to reduce morbidity in these patients, many survivors remain burdened with significant medical complications. In a small percentage of patients, complications may result in death even during extended remission of craniopharyngioma. Because of the broad spectrum or morbidities experienced, survivors of craniopharyngioma continue to benefit from multidisciplinary care.

Continual reassessment method vs. traditional empirically based design: modifications motivated by Phase I trials in pediatric oncology by the Pediatric Brain Tumor Consortium.

In this article we provide additional support for the use of a model-based design in pediatric Phase I trials and present our modifications to the continual reassessment method (CRM), which were largely motivated by specific challenges we encountered in the context of the Pediatric Brain Tumor Consortium trials. We also summarize the results of our extensive simulations studying the operating characteristics of our modified approach and contrasting it to the empirically based traditional method (TM). Compared to the TM, our simulations indicate that the modified version of CRM is more accurate, exposes fewer patients to potentially toxic doses, and tends to require fewer patients. Further, the CRM-based MTD has a consistent definition across trials, which is important, especially in a consortium setting where multiple agents are being tested in studies that are often running simultaneously and accruing from the same patient population.

Seizure Recurrence and Risk Factors after Antiepilepsy Drug Withdrawal in Children with Brain Tumors

Summary:  Purpose: To study seizure outcome after antiepilepsy drug (AED) withdrawal in brain tumor patients and to analyze risk factors for seizure recurrence.

Tin Whisker Electrical Short Circuit Characteristics—Part II

Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has an unknown probability associated with it. Note however that due to contact resistance, electrical shorts may not occur at lower voltage levels. In our first paper, we developed an empirical probability model for tin whisker shorting. In this paper, we develop a more comprehensive empirical model using a refined experiment with a larger sample size, in which we studied the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From the resulting data, we estimated the probability distribution of an electrical short, as a function of voltage. In addition, the unexpected polycrystalline structure seen in the focused ion beam (FIB) cross section in the first experiment was confirmed in this experiment using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guides tin plating to determine its finish.

Phase I trial of p28 (NSC745104), a non-HDM2-mediated peptide inhibitor of p53 ubiquitination in pediatric patients with recurrent or progressive central nervous system tumors: A Pediatric Brain Tumor Consortium Study.

BACKGROUND p53 is a promising target in human cancer. p28 is a cell-penetrating peptide that preferentially enters cancer cells and binds to both wild-type and mutant p53 protein, inhibiting COP1-mediated ubiquitination and proteasomal degradation. This results in increased levels of p53, which induces cell cycle arrest at G2/M. We conducted a phase I study to determine the maximum-tolerated dose (MTD) and describe the dose-limiting toxicities (DLTs) and pharmacokinetics (PKs) of p28 in children. METHODS Children aged 3-21 years with recurrent or progressive central nervous system tumors were eligible. Intravenous p28 was administered 3 times weekly for 4 consecutive weeks of a 6-week cycle at 4.16 mg/kg/dose (the adult recommended phase II dose) using a rolling-6 study design. Expression status of p53 was characterized by immunohistochemistry, and serum PK parameters were established on the second dose. RESULTS Of the 18 eligible patients enrolled in the study, 12 completed the DLT monitoring period and were evaluable for toxicity. p28 was well-tolerated; 7 participants received ≥2 courses, and the most common adverse event attributed to the drug was transient grade 1 infusion-related reaction. PK analysis revealed a profile similar to adults; however, an increased area under the curve was observed in pediatric patients. High p53 expression in tumor cell nuclei was observed in 6 of 12 available tissue samples. There were no objective responses; 2 participants remained stable on the study for >4 cycles. CONCLUSIONS This phase I study demonstrated that p28 is well-tolerated in children with recurrent CNS malignancies at the adult recommended phase II dose.

A permutation-based method to identify loss-of-heterozygosity using paired genotype microarray data.

Background SNP genotyping microarrays may be used to detect regions of loss-of-heterozygosity (LOH). Genotype array data are collected for tumor tissue and germline tissue samples from each subject. For each subject, an initial call of LOH or non-LOH is generated for each marker via straightforward comparison of the genotype call across each tissue sample pair [1]. The genotype calls are generated with some error. Therefore, statistical models are used to analyze the pattern of LOH calls to infer regions of LOH for each subject [1].

An Operational Perspective of Challenging Statistical Dogma While Establishing a Modern, Secure Distributed Data Management and Imaging Transport System: The Pediatric Brain Tumor Consortium Phase I Experience

The Pediatric Brain Tumor Consortium (PBTC) is a multidisciplinary cooperative research organization devoted to the study of correlative tumor biology and new therapies for primary central nervous system (CNS) tumors of childhood. The PBTC was created in 1999 to conduct early‐phase studies in a rapid fashion in order to provide sound scientific foundation for the Childrens Oncology Group to conduct definitive trials. The Operations and Biostatistics Center (OBC) of the PBTC is responsible for centrally administering study design and trial development, study conduct and monitoring, data collection and management as well as various regulatory and compliance processes. The phase I designs utilized for the consortium trials have accommodated challenges unique to pediatric trials such as body surface area (BSA)‐based dosing in the absence of pediatric formulations of oral agents. Further during the past decade, the OBC has developed and implemented a state‐of‐the‐art secure and efficient internet‐based paperless distributed data management system. Additional web‐based systems are also in place for tracking and distributing correlative study data as well as neuroimaging files. These systems enable effective communications among the members of the consortium and facilitate the conduct and timely reporting of multi‐institutional early‐phase clinical trials.