Medulloblastomas and central nervous system primitive neuroectodermal tumors

An efficient and novel treatment regimen including temozolomide for medulloblastoma: a case study

Background:

The central nervous system (CNS) embryonal tumour is a rare malignancy reported in adults and more commonly in children. The most available treatments may cause neurological dysfunctions requiring clinical attention.

Case presented:

A 29-year-old male was referred with ataxia and diplopia, and brain imaging revealed a posterior fossa lesion suggesting medulloblastoma. The tumour and related symptoms were notably alleviated following treatment with dexamethasone. Following the recurrence of tumour, a biopsy and pathology report, the diagnosis of desmoplastic/nodular medulloblastoma was confirmed. The patient underwent 18 fractions of 180 cGy spine and whole-brain radiation therapy (RT). In addition, 5400 cGy irradiation in 12 fractions was given to the posterior fossa together with 2 mg/m2 intravenous vincristine (VCR) weekly over 6 weeks. Following a 3-week break, the patient was scheduled to receive 150 mg/m2/day temozolomide for 5 days, 2 mg VCR and 65 mg/m2/day cisplatin every 3 weeks for 8 cycles.

Conclusion:

The patient gained survival benefit to date (60 months since diagnosis) with favourable life quality. The promising response in this one exemplary case study proposes that a combined chemotherapy regimen including temozolomide, vincristine and cisplatin is an effective treatment choice for CNS embryonal tumours following RT; however, the further evaluation and a randomised clinical trial are needed.

In vivo bio-imaging using chlorotoxin-based conjugates

Surgical resection remains the primary component of cancer therapy. The precision required to successfully separate cancer tissue from normal tissue relies heavily on the surgeon's ability to delineate the tumor margins. Despite recent advances in surgical guidance and monitoring systems, intra-operative identification of these margins remains imprecise and directly influences patient prognosis. If the surgeon had improved tools to distinguish these margins, tumor progression and unacceptable morbidity could be avoided. In this article, we review the history of chlorotoxin and its tumor specificity and discuss the research currently being generated to target optical imaging agents to cancer tissue.

Proton radiotherapy for solid tumors of childhood

The increasing efficacy of pediatric cancer therapy over the past four decades has produced many long-term survivors that now struggle with serious treatment related morbidities affecting their quality of life. Radiation therapy is responsible for a significant proportion of these late effects, but a relatively new and emerging modality, proton radiotherapy hold great promise to drastically reduce these treatment related late effects in long term survivors by sparing dose to normal tissues. Dosimetric studies of proton radiotherapy compared with best available photon based treatment show significant dose sparing to developing normal tissues. Furthermore, clinical data are now emerging that begin to quantify the benefit in decreased late treatment effects while maintaining excellent cancer control rates.

Sunitinib induces PTEN expression and inhibits PDGFR signaling and migration of medulloblastoma cells

We previously showed that inhibition of the platelet-derived growth factor receptor (PDGFR) blocks the survival and migration of medulloblastoma cells. Identification of in vitro PDGFR-targeting pharmacologic agents that are suitable for preclinical testing in medulloblastoma models in vivo will be critical for efficiently translating these agents to clinical investigation in children with medulloblastoma. In this study, we investigated whether the multi-tyrosine kinase inhibitor sunitinib, effectively inhibits PDGFR signaling required for medulloblastoma cell migration. Daoy and D556 human medulloblastoma cells pre-treated for 1 h with 0.2 μM sunitinib demonstrated induction of PTEN expression and significant inhibition of PDGFR signaling activity and transactivation of EGFR, in a RAS-independent manner, in response to PDGF-BB stimulation. Sunitinib pre-treatment markedly reduced medulloblastoma cell migration in response to both PDGF-BB and 10% serum at 4 and 24 h after treatment. Pre-treatment with sunitinib for 1 h also resulted in detachment and decreased viability of D556, but not Daoy, cells and only after 48 h following treatment. However, sunitinib did not induce apoptosis in either cell line at any time point, indicating that the anti-migratory effects of sunitinib were not due to impeding cell survival. Sunitinib similarly inhibited PDGFR signaling and migration of primary murine Smo/Smo medulloblastoma cells, suggesting that the Smo/Smo mouse is an appropriate model for preclinical testing of sunitinib. These results indicate that sunitinib may be an important pharmacologic agent for the treatment of invasive medulloblastoma, particularly given evidence of its ability to cross the blood-brain barrier to target tumor cells, and thus warrants further in vivo testing for confirmation of efficacy.

Enhanced expression of DNA topoisomerase II genes in human medulloblastoma and its possible association with etoposide sensitivity

Medulloblastoma (MB) is the most common malignant neuroepithelial tumor of childhood. The DNA topoisomerase II (Topo II) inhibitor etoposide has been widely used for the treatment of MBs; however, it remains unknown whether MB cells are more sensitive to etoposide than other malignant neuroepithelial tumor cells. In this study, we tested the chemosensitivities of malignant neuroepithelial tumors (26 glioblastomas, 9 anaplastic astrocytomas, and 5 MBs) to etoposide and vincristine using the succinate dehydrogenase inhibition test and found that MB cells are more sensitive to etoposide and more resistant to vincristine than other tumor cells. We performed quantitative reverse-transcription polymerase chain reaction to evaluate the expression of genes related to etoposide sensitivity, and found co-overexpression of DNA topoisomerase II (Topo II) alpha and beta mRNA in MBs. In addition, the levels of Topo IIalpha and beta mRNA in these tumors correlated with etoposide sensitivity. Immunohistochemical studies using surgical samples of these tumors demonstrated that the percentages of Topo IIalpha immunopositive cells (Topo IIalpha labeling index) correlated with those of Ki-67 immunopositive cells (MIB-1 labeling index); however, neither the Topo IIalpha nor the MIB-1 labeling index correlated with the levels of Topo IIalpha mRNA or etoposide sensitivity. Based on these observations, Topo IIalpha and beta mRNA expression, but not the Topo IIalpha labeling index, might be a useful marker for sensitivity to etoposide in human malignant neuroepithelial tumors.

A paediatric supratentorial primitive neuroectodermal tumour associated with malignant astrocytic transformation and a clonal origin of both components

The case of a 7-year-old boy suffering from a supratentorial primitive neuroectodermal tumour (sPNET) at the age of 5 is presented. The tumour has been characterized by astrocytic areas within the sPNET revealing malignant transformation up to a multiform glioblastoma during the course of the disease. The clonal origin of both tumour components was established by loss of heterozygosity (LOH) analysis. Clinically, the tumour showed an aggressive biological behaviour with two recurrences. We discuss this very rare case and the first description of the clonal origin of distinct and distinguishable tumour components taking into consideration published literature.

Peripheral primitive neuroectodermal tumor/Ewing's sarcoma of the craniospinal vault: case reports and review

The peripheral primitive neuroectodermal tumor/Ewing's sarcoma family tumor (pPNET/ESFT) group includes small round cell tumors of the bone, soft tissue, and nerve with morphological attributes of the germinal neuroepithelium. Peripheral PNETs/ESFTs also occur within the craniospinal vault, a region including the central nervous system, the meninges, and the cranial and spinal nerve roots. Gene rearrangements between the EWS gene on chromosome 22q12 and members of the ETS gene family are common in and specific to pPNETs/ESFTs. Another defining characteristic of pPNETs/ESFTs is their membranous expression of the MIC2 gene product. We describe 2 cases of pPNETs within the craniospinal vault. An intradural tumor arising from the nerve roots of the cauda equina was discovered in a 32-year-old man presenting with radiculopathic back pain and lower-extremity weakness. An intracranial pPNET that mimicked a meningioma was found in a 21-year-old man presenting with headache and visual disturbances. MIC2 gene product expression and EWS/ETS gene rearrangement were detected in both case patients. The literature with regard to pPNETs/ESFTs arising within the craniospinal vault is reviewed.

Role of Radiotherapy in Supratentorial Primitive Neuroectodermal Tumor in Young Children: Results of the German HIT-SKK87 and HIT-SKK92 Trials

Purpose

To assess the outcome of young children with supratentorial primitive neuroectodermal tumor (stPNET) treated by intensive postoperative chemotherapy alone compared with treatment with chemotherapy and delayed radiotherapy (RT).

Patients and Methods

From 1987 to 1992, children younger than 3 years of age with stPNET were enrolled in the HIT-SKK87 trial in Germany and Austria. After surgery, low-risk patients received maintenance chemotherapy before RT. In high-risk patients, intensive induction chemotherapy was followed by maintenance chemotherapy until delayed RT was initiated. In the following trial, HIT-SKK92 methotrexate-based chemotherapy was applied. In children with complete remission after three cycles, therapy was finished without irradiation. Otherwise, radiotherapy or salvage chemotherapy was administered.

Results

Twenty-nine children were eligible (age, 3.0 to 37.0 months). All children received chemotherapy. In 15 children, no RT was administered. Four children had tumor progression during chemotherapy and underwent irradiation. In 10 patients, RT was given after chemotherapy. Overall survival (OS) and progression-free survival (PFS) rates after 3 years were 17.2% and 14.9%, respectively. Twenty-four children relapsed (13 at the tumor site only, three at distant site, and eight at both local and distant sites). Positive impact on survival was observed in children with complete resection but without statistical significance. Administration of RT was the only significant predictive factor for OS and PFS. Only one child not having RT survived.

Conclusion

Outcome of infants and babies with stPNET is unsatisfactory. Omission of RT jeopardizes survival, even if intensive chemotherapy is applied. We suggest to limit any delay of RT to a maximum of 6 months even in young children.