Faculty Bibliography

Pediatric glioblastoma is one of the most common and most deadly brain tumors in childhood. Using an integrative genetic analysis of 53 pediatric glioblastomas and five in vitro model systems, we identified previously unidentified gene fusions involving the MET oncogene in ~10% of cases. These MET fusions activated mitogen-activated protein kinase (MAPK) signaling and, in cooperation with lesions compromising cell cycle regulation, induced aggressive glial tumors in vivo. MET inhibitors suppressed MET tumor growth in xenograft models. Finally, we treated a pediatric patient bearing a MET-fusion-expressing glioblastoma with the targeted inhibitor crizotinib. This therapy led to substantial tumor shrinkage and associated relief of symptoms, but new treatment-resistant lesions appeared, indicating that combination therapies are likely necessary to achieve a durable clinical response.

PURPOSE: To report the final analysis of survival outcomes for children with newly diagnosed high-grade glioma (HGG) treated on the "Head Start" (HS) II and III protocols with chemotherapy and intent to avoid irradiation in children <6 years old. PATIENTS AND METHODS: Between 1997 and 2009, 32 eligible children were enrolled in HS II and III with anaplastic astrocytoma (AA, n = 19), glioblastoma multiforme (GBM, n = 11), or other HGG (n = 2). Central pathology review was completed on 78% of patients. Patients with predominantly brainstem tumors were excluded. Patients were to be treated with single induction chemotherapy regimen C, comprising four cycles of vincristine, carboplatin, and temozolomide. Following induction, patients underwent marrow-ablative chemotherapy and autologous hematopoietic cell rescue. Irradiation was used for patients with residual tumor after consolidation or >6 years old or at the time of tumor progression. RESULTS: The 5-year event-free survival (EFS) and overall survival (OS) for all HGG patients were 25 +/- 8% and 36 +/- 9%, respectively. The EFS at 5 years for patients with AA and GBM were 24 +/- 11% and 30 +/- 16%, respectively (P = 0.65). The OS at 5 years for patients with AA and GBM was 34 +/- 12% and 35 +/- 16%, respectively (P = 0.83). Children <36 months old experienced improved 5-year EFS and OS of 44 +/- 17% and 63 +/- 17%, compared with children 36-71 months old (31 +/- 13% and 38 +/- 14%) and children >72 months old (0% and 13 +/- 12%). CONCLUSIONS: Irradiation-avoiding treatment strategies should be evaluated further in young children with HGG given similar survival rates to older children receiving standard irradiation-containing therapies.

Patients with marker-positive central nervous system (CNS) germ cell tumors are typically monitored for tumor recurrence with both tumor markers (AFP and b-hCG) and MRI. We hypothesize that the recurrence of these tumors will always be accompanied by an elevation in tumor markers, and that surveillance MRI may not be necessary. We retrospectively identified 28 patients with CNS germ cell tumors treated at our institution that presented with an elevated serum or cerebrospinal fluid (CSF) tumor marker at the time of diagnosis. We then identified those who had a tumor recurrence after having been in remission and whether each recurrence was detected via MRI changes, elevated tumor markers, or both. Four patients suffered a tumor recurrence. Only one patient had simultaneously elevated tumor markers and MRI evidence of recurrence. Two patients had evidence of recurrence on MRI without corresponding elevations in serum or CSF tumor markers. One patient had abnormal tumor markers with no evidence of recurrence on MRI until 6 months later. We conclude that in patients with marker-positive CNS germ cell tumors who achieve complete remission, continued surveillance imaging in addition to measurement of tumor markers is indicated to detect recurrences.

BACKGROUND: Central nervous system (CNS) germ cell tumors account for 3 % of all pediatric brain tumors in the USA. Presenting symptoms are typically location based with pineal tumors presenting with obstructive hydrocephalus and suprasellar tumors with hypothalamic/pituitary dysfunction and ophthalmologic abnormalities. Psychiatric manifestations such as psychosis and behavioral changes are atypical presentations of CNS germ cell tumors, with only 11 previously reported cases. METHODS: This is a retrospective case series describing patients with CNS germ cell tumors with an atypical presentation including psychiatric manifestations. Information regarding clinical presentation, treatment course, and outcome were obtained. RESULTS: We report seven patients who presented with psychiatric symptoms consisting of psychomotor delay as well as behavioral and mood changes. Six of the seven patients were diagnosed >/=6 months after onset of psychiatric symptoms. All of the seven are alive but five continue to have neurologic and psychiatric issues post treatment. CONCLUSIONS: Atypical presentations of CNS germ cell tumors can delay diagnosis and treatment and may be secondary to atypical locations as well as endocrine dysfunction manifesting as psychiatric symptoms. Delayed diagnosis did not appear to affect survival but earlier diagnosis may potentially be associated with better neurologic and psychiatric outcome. Patients who present with these symptoms and atypical neuroimaging should have a thorough evaluation for CNS germ cell tumors including serum and CSF markers. Clinicians should be aware of these less common presentations to aid in prompt diagnosis and treatment.

Schwannomatosis is characterized by multiple non-intradermal schwannomas with patients often presenting with a painful mass in their extremities. In this syndrome malignant transformation of schwannomas is rare in spite of their large size at presentation. Non-invasive measures of assessing the biological behavior of plexiform neurofibromas in neurofibromatosis type 1 such as positron emission tomography (PET), CT scanning and MRI are well characterized but little information has been published on the use of PET imaging in schwannomatosis. We report a unique clinical presentation portraying the use of PET imaging in schwannomatosis. A 27-year-old woman presented with multiple, rapidly growing, large and painful schwannomas confirmed to be related to a constitutional mutation in the SMARCB1 complex. Whole body PET/MRI revealed numerous PET-avid tumors suggestive of malignant peripheral nerve sheath tumors. Surgery was performed on multiple tumors and none of them had histologic evidence of malignant transformation. Overall, PET imaging may not be a reliable predictor of malignant transformation in schwannomatosis, tempering enthusiasm for surgical interventions for tumors not producing significant clinical signs or symptoms.

Treatment for intracranial germ cell tumors includes platinum-based chemotherapy and external beam radiation therapy, which are risk factors for hearing loss. In patients who experience significant sensorineural ototoxicity due to cochlear hair cell injury, dose reduction of chemotherapy may be necessary. This report describes an adolescent male, with excellent treatment response for an intracranial nongerminomatous germ cell tumor, who developed sensorineural hearing loss, which was central rather than cochlear in origin and unrelated to carboplatin. This patient highlights the need to carefully differentiate the type and etiology of sensorineural hearing loss in patients with brain tumors receiving ototoxic chemotherapy.