Feasibility of four consecutive high-dose chemotherapy cycles with stem-cell rescue for patients with newly diagnosed medulloblastoma or supratentorial primitive neuroectodermal tumor after craniospinal radiotherapy: results of a collaborative study

Motor and sensory impairment in survivors of childhood central nervous system (CNS) tumors in the St. Jude Lifetime Cohort (SJLIFE)

BACKGROUND

Survivors of childhood central nervous system (CNS) tumors can develop motor and sensory impairment from their cancer and treatment history. We estimated the prevalence of motor and sensory impairment in survivors compared with controls through clinical assessment and identified associated treatment exposures and functional, quality of life (QOL), and social outcomes.

METHODS

Survivors of childhood CNS tumors from the St. Jude Lifetime Cohort (n = 378, median [range] age 24.0 [18.0-53.0] years, 43.4% female) ≥5 years from diagnosis and controls (n = 445, median [range] age 34.0 [18.0-70.0] years, 55.7% female) completed in-person evaluation for motor and sensory impairment using the modified Total Neuropathy Score. Impairment was graded by modified Common Terminology Criteria for Adverse Events. Multivariable models estimated associations between grade ≥2 motor/sensory impairment, individual/treatment characteristics, and secondary outcomes (function by Physical Performance Test, fitness by physiologic cost index, QOL by Medical Outcomes Survey Short Form-36 physical/mental summary scores, social attainment).

RESULTS

Grade ≥2 motor or sensory impairment was more prevalent in survivors (24.1%, 95% Confidence Interval [CI] 19.8%-29.4%) than controls (2.9%, CI 1.4-4.5%). Among survivors, in multivariable models, motor impairment was associated with vinca exposure <15 mg/m2 versus none (OR 4.38, CI 1.06-18.08) and etoposide exposure >2036 mg/m2 versus none (OR 12.61, CI 2.19-72.72). Sensory impairment was associated with older age at diagnosis (OR 1.09, CI 1.01-1.16) and craniospinal irradiation versus none (OR 4.39, CI 1.68-11.50). There were lower odds of motor/sensory impairment in survivors treated in the year 2000 or later versus before 1990 (Motor: OR 0.29, CI 0.10-0.84, Sensory: OR 0.35, CI 0.13-0.96). Motor impairment was associated with impaired physical QOL (OR 2.64, CI 1.22-5.72).

CONCLUSIONS

In survivors of childhood CNS tumors, motor and sensory impairment is prevalent by clinical assessment, especially after exposure to etoposide, vinca, or craniospinal radiation. Treating motor impairment may improve survivors' QOL.

Helical tomotherapy craniospinal irradiation in primary brain tumours: Toxicities and outcomes in a peadiatric and adult population

Objective

As craniospinal irradiation (CSI) is delivered more frequently by helical tomotherapy (HT) with few reports about late effects, we analysed all patients treated in our centre over an 11-year period.

Methods and materials

Our study included all patients that underwent CSI by HT, between September 2009 and January 2020, in the Department of Radiation Oncology of the Toulouse Cancer Institute. Acute radiotherapy toxicities were reported and medium- to long-term outcomes analysed.

Results

Among the 79 patients included, 70.9 % were younger than 18 years at diagnosis, the median age was 13 (range: 1-52) at the time of radiation therapy, 67.1 % of patients had medulloblastoma. Half of them (49.4 %) had a metastatic disease at diagnosis. The median dose of CSI was 36 Gy (range, 18-36). Seventy-seven patients received a radiation boost to the original location of the primary tumour (97.5 %), 32 patients also received a boost to their metastatic sites (40.5 %). Median follow-up was 55.5 months (95 %CI = [41.2; 71.8]). The 3-year event-free survival rate was 66.3 % (95 %CI = [54.2; 75.9]). Most patients presented with acute haematological toxicities during CSI (85.9 %), predominantly severe thrombocytopenia (39.7 %). Among the 64 patients assessed for medium- and long-term outcomes, 52 survived and 47 were alive and disease-free at the latest follow-up visit on record. There were 3.8 % secondary tumours: two meningiomas and one diffuse intrinsic pontine glioma. Adult and paediatric patients respectively presented with secondary cataract (4.3 % vs 22.0 %), persistent hearing disorders (26.1 % vs 29.3 %), pulmonary or cardiac late effects (4.3 % vs 2.4 %), hormonal pituitary gland deficiencies (30.0 % vs 56.8 %) and psycho-cognitive disorders (56.5 % vs 53.7 %).

Conclusion

CSI dispensed by HT, did not result in any additional acute or late toxicities when compared to 3D-CSI. There was no increase in the secondary tumour rate compared to that reported in the literature.

A review on advancements in the application of starch-based nanomaterials in biomedicine: Precision drug delivery and cancer therapy

The burgeoning field of starch-based nanomaterials in biomedical applications has perceived notable progressions, with a particular emphasis on their pivotal role in precision drug delivery and the inhibition of tumor growth. The complicated challenges in current biomedical research require innovative approaches for improved therapeutic outcomes, prompting an exploration into the possible of starch-based nanomaterials. The conceptualization of this review emerged from recognizing the need for a comprehensive examination of the structural attributes, versatile properties, and mechanisms underlying the efficiency of starch-based nanomaterials in inhibiting tumor growth and enabling targeted drug delivery. This review delineates the substantial growth in utilizing starch-based nanomaterials, elucidating their small size, high surface-volume ratio, and biocompatibility, predominantly emphasizing their possible to actively recognize cancer cells, deliver anticancer drugs, and combat tumors efficiently. The investigation of these nanomaterials encompasses to improving biocompatibility and targeting specific tissues, thereby contributing to the evolving landscape of precision medicine. The review accomplishes by highlighting the auspicious strategies and modern developments in the field, envisioning a future where starch-based nanomaterials play a transformative role in molecular nanomaterials, evolving biomedical sciences. The translation of these advancements into clinical applications holds the potential to revolutionize targeted drug delivery and expand therapeutic outcomes in the realm of precision medicine.

High-Dose Chemotherapy in Children with Newly Diagnosed Medulloblastoma

High-dose chemotherapy with stem cell rescue has been used as an adjuvant therapy or as salvage therapy to treat pediatric patients with brain tumors, and to avoid deleterious side effects of radiotherapy in infants and very young children. Here, we present the most recent trials using high-dose chemotherapy regimens for medulloblastoma in children, and we discuss their contribution to improved survival and describe their toxicity profile and limitations.

Preradiation Chemotherapy for Adult High-risk Medulloblastoma: A Trial of the ECOG-ACRIN Cancer Research Group (E4397)

OBJECTIVES

To assess the long-term outcomes and objective response (OR) to preradiation chemotherapy and radiation in adult high-risk medulloblastoma.

MATERIALS AND METHODS

In this prospective phase II trial, adults with high-risk medulloblastoma were treated with 3 cycles of preradiation cisplatin, etoposide, cyclophosphamide, and vincristine followed by craniospinal radiation (CSI). OR, progression-free survival (PFS), overall survival (OS), and toxicities were assessed.

RESULTS

Eleven patients were enrolled over a 6-year period. Six (55%) had subarachnoid metastases. Two (18%) had an OR to preradiation chemotherapy. Two (18%) progressed while on chemotherapy. Completion of CSI was not compromised. The OR rate after chemotherapy and radiation was 45% (5/11). Nonevaluable patients at both time-points weakened the response data conclusions. Median PFS was 43.8 months. Five-year PFS was 27%. Five-year OS was 55%. Nonmetastatic (M0) and metastatic (M+) patients had similar outcomes.

CONCLUSIONS

The OR to this preradiation chemotherapy regimen is lower than anticipated from the adult and pediatric literature raising a question about comparative efficacy of chemotherapy in different age groups. The OS achieved is similar to retrospective adult series, but worse than pediatric outcomes. Although this regimen can be administered without compromising delivery of CSI, our results do not provide support for the use of this neoadjuvant chemotherapy for adult medulloblastoma.

Atypical teratoid/rhabdoid tumors in children treated with multimodal therapies: The necessity of upfront radiotherapy after surgery

BACKGROUND

Atypical teratoid/rhabdoid tumor (ATRT) is a rare malignant pediatric brain tumor with a dismal prognosis. We evaluated the efficacy of multimodal therapy in children with ATRT.

PROCEDURE

Nine children diagnosed with cranial ATRT, who received multimodal therapy between 2005 and 2014, including surgical resection followed by radiotherapy (RT), systemic chemotherapy (CT), and high-dose chemotherapy/stem cell transplantation (HDCT/SCT), were analyzed retrospectively. The median age at diagnosis was 32 months. Initial treatment included surgery in eight patients (88%), CT in all (100%), RT in eight (88%), and HDCT/SCT in seven (78%).

RESULTS

The median follow-up period for survivors was 21 months. The 2-year progression-free rate was 66.7%. Two patients had progression 4 and 17 months after diagnosis. One received multimodal treatment, including surgery and upfront CT with delayed RT; the other underwent surgery and upfront CT without RT. The 2-year event-free survival and overall survival rates were 46.7% and 62.2%, respectively. Hematologic toxicity of grade 3 or more was observed in six patients treated with HDCT/SCT and two who underwent craniospinal irradiation. Deaths were attributed to progressive disease (n = 2) and treatment-related toxicity (n = 2) from sepsis and acute respiratory failure after CT and HDCT/SCT.

CONCLUSIONS

Maximal safe resection in conjunction with upfront RT is a reasonable multimodal treatment in patients with ATRT for prolonging progression-free survival. Further research may help determine the optimal parameters for reducing treatment toxicity, such as intensity of HDCT/SCT and the RT field.

Atypical Teratoid Rhabdoid Tumor: Two Case Reports and an Analysis of Adult Cases with Implications for Pathophysiology and Treatment

We present the first quantitative analysis of atypical teratoid rhabdoid tumors (ATRT) in adults, including two patients from our own institutions. These are of interest as one occurred during pregnancy and one is a long-term survivor. Our review of pathological findings of 50 reported cases of adult ATRT leads us to propose a solely ectodermal origin for the tumor and that epithelial–mesenchymal transition (EMT) is a defining feature. Thus, the term ATRT may be misleading. Our review of clinical findings shows that ATRT tends to originate in mid-line structures adjacent to the CSF, leading to a high rate of leptomeningeal dissemination. Thus, we hypothesize that residual undifferentiated ectoderm in the circumventricular organs, particularly the pituitary and pineal glands, is the most common origin for these tumors. We note that if growth is not arrested soon after diagnosis, or after the first relapse/progression, death is almost universal. While typically rapidly fatal (as in our first case), long-term remission is possible (as in our second). Significant predictors of prognosis were the extent of resection and the use of chemotherapy. Glial differentiation (GFAP staining) was strongly associated with leptomeningeal metastases (chi-squared p = 0.02) and both predicted markedly worse outcomes. Clinical trials including adults are rare. ATRT is primarily a disease of infancy and radiotherapy is generally avoided in those aged less than 3 years old. Treatment options in adults differ from infants in that cranio-spinal irradiation is a viable adjunct to systemic chemotherapy in the adult population. Given the grave prognosis, this combined approach appears reasonable. As effective chemotherapy is likely to cause myelosuppression, we recommend that stem-cell rescue be available locally.

Childhood medulloblastoma

Medulloblastoma accounts for 15-20% of childhood nervous system tumours. The risk of dying was reduced by 30% in the last twenty years. Patients are divided in risk strata according to post-surgical disease, dissemination, histology and some molecular features such as WNT subgroup and MYC status. Sixty to 70% of patients older than 3 years are assigned to the average-risk group. High-risk patients include those with disseminated and/or residual disease, large cell and/or anaplastic histotypes, MYC genes amplification. Current and currently planned clinical trials will: (1) evaluate the feasibility of reducing both the dose of craniospinal irradiation and the volume of the posterior fossa radiotherapy (RT) for those patients at low biologic risk, commonly identified as those having a medulloblastoma of the WNT subgroup; (2) determine whether intensification of chemotherapy (CT) or irradiation can improve outcome in patients with high-risk disease; (3) find target therapies allowing tailored therapies especially for relapsing patients and those with higher biological risk.

The role of high-dose myeloablative chemotherapy with haematopoietic stem cell transplantation (HSCT) in children with central nervous system (CNS) tumours: protocol for a systematic review and meta-analysis

OBJECTIVES

The objective of the study is to conduct a systematic review to compare the effects of high-dose chemotherapy (HDCT) with autologous haematopoietic stem cell transplantation (HSCT) versus standard-dose chemotherapy (SDCT) in children with malignant central nervous system (CNS) tumours.

METHODS

Standard systematic review methods aimed at minimising bias will be employed for study identification, selection and data extraction. Ten electronic databases will be searched, along with citation searching and reference checking. Studies assessing the effects of HDCT with HSCT in children with CNS tumours will be included. The outcomes are survival (overall, progression-free, event-free, disease-free), response rates, short- and long-term adverse events and health-related quality of life (HRQoL). Two reviewers will independently screen and select randomised and non-randomised controlled trials and controlled and uncontrolled observational studies for inclusion. Quality assessment will be tailored to the different study designs. Where possible data will be summarised using combined estimates of effect for the hazard ratio for survival outcomes and the risk ratio for response rates. A fixed effect model will be used; sub-group analyses and meta-regression will be used to explore potential sources of heterogeneity between studies.

DISCUSSION

Given the poor prognosis of malignant brain tumours in children in terms of survival and quality of life, this review will help guide clinical practice by summarising the current evidence on the use of high-dose myeloblative chemotherapy with stem cell support in children with CNS tumours.

Treatment outcomes and late toxicities in patients with embryonal central nervous system tumors

BACKGROUND

Standard treatment strategies for embryonal central nervous system (CNS) tumors have not yet been established. We treated these tumors using an original chemoradiation therapy protocol; the clinical outcomes and toxicities were retrospectively evaluated.

METHODS

Twenty-four patients were enrolled including sixteen with medulloblastoma, four with supratentorial primitive neuroectodermal tumor (sPNET), three with atypical teratoid/rhabdoid tumor, and one with pineoblastoma. Immediately after diagnosis, all patients underwent surgery initially. They were then categorized as high- or average-risk groups independent of tumor type/pathogenesis. The average-risk group included patients who were aged ≥3 years at diagnosis, had non-metastatic disease at diagnosis (M0), and had undergone gross total resection. Other patients were categorized as the high-risk group; this group received more intensive treatment than the average-risk group, including high-dose chemotherapy with autologous stem-cell transplantation. All patients received craniospinal irradiation (CSI). The CSI dose was 23.4 Gy for M0 patients aged ≥5 years, 18 Gy for M0 patients aged <5 years, and 30-36 Gy for all patients with M + disease. The total dose to the primary tumor bed was 54 Gy.

RESULTS

The median follow-up time was 73.5 (range, 19-118) months. The 5-year progression-free survival (PFS) and overall survival (OS) rates were 71.1 and 88.9%, respectively in the average-risk group (n = 9) and 66.7 and 71.1%, respectively in the high-risk group (n = 15). The PFS and OS rates were not significantly different between the average- and high-risk groups. In patients with medulloblastoma only, these rates were also not significantly different between the average- and high-risk groups. Three of four patients with sPNET were disease free. The height standard deviation score (SDS) was significantly decreased at the last assessment relative to that at diagnosis (P < 0.0001). The latest median height SDS was -1.6 (range, 0.9 to -4.8), and the latest median full-scale intelligence quotient (FSIQ) score was 86 (range, 59-128). The CSI doses and age at the start of radiation therapy did not influence clinical outcomes, height SDSs, and FSIQ scores.

CONCLUSIONS

Our original protocol for patients with embryonal CNS tumors was feasible and yielded favorable clinical outcomes.

Tandem high-dose chemotherapy and autologous stem cell rescue in children with newly diagnosed high-risk medulloblastoma or supratentorial primitive neuro-ectodermic tumors

BACKGROUND

To assess the feasibility and effectiveness of high-dose chemotherapy (HDC) with stem cell support followed by conventional craniospinal radiotherapy (RT) as treatment for children older than 5 years of age with newly diagnosed high-risk medulloblastoma (MB) or supratentorial PNET (sPNET).

PROCEDURE

Between May 2001 and April 2010, 24 children older than 5 years of age (MB = 21; sPNET = 3), fulfilling inclusion criteria at diagnosis, were treated at Gustave Roussy. After conventional chemotherapy, they received two courses of high-dose thiotepa (600 mg/m(2)) followed by craniospinal RT.

RESULTS

The median follow-up was 4.4 years (range, 0.8-11.3 years). For children with metastatic MB, the 5-year event-free survival (EFS) and overall survival (OS) were 72% and 83%, respectively. The toxicity was manageable. No toxic death occurred. At the most recent evaluation, among the 24 children who had at least one Full Scale Intellectual Quotient (FSIQ) examination at a median follow-up of 3.79 years after diagnosis, the mean estimated FSIQ was 82 (range, 56-114).

CONCLUSIONS

In children with metastatic MB, tandem HDCT with ASCT followed by conventional craniospinal RT proved its feasibility without jeopardizing survival.

Autologous hematopoietic stem cell transplantation for pediatric solid tumors

While advances in the treatment of pediatric cancers have increased cure rates, children with metastatic or recurrent solid tumors have a dismal prognosis despite initial transient responses to therapy. Autologous hematopoietic stem cell transplantation takes advantage of the steep dose-response relationship observed with many chemotherapeutic agents. While clearly demonstrated to improve outcomes in patients with metastatic neuroblastoma, autologous hematopoietic stem cell transplantation is also frequently used to treat patients with other high-risk diseases such as Ewing sarcoma, osteosarcoma, rhabdomyosarcoma, Wilms' tumor, retinoblastoma, germ cell tumors, lymphomas and brain tumors. Most published experience consists of retrospective, single-arm studies; randomized clinical trials are lacking, due in part to the rarity of pediatric cancers treatable by autologous hematopoietic stem cell transplantation. These published literature demonstrate that autologous hematopoietic stem cell transplantation results in most cases in equivalent or superior outcomes when compared with conventional therapies. However, patient heterogeneity, patient selection, graft characteristics and processing and the varied conditioning regimens are additional factors to consider. Since the inception of autologous hematopoietic stem cell transplantation, regimen-related toxicity has markedly decreased and the vast majority of treatment failures are now due to disease recurrence. Prospective clinical trials are needed to identify specific high-risk patient populations, with randomization (when possible) to compare outcomes of patients undergoing autologous hematopoietic stem cell transplantation with those receiving standard therapy. In addition, investigators need to better define the role of autologous hematopoietic stem cell transplantation in these solid tumors, particularly in combination with other therapeutic modalities such as immunotherapy and novel cell processing methodologies.

Evolving of therapeutic strategies for CNS-PNET

BACKGROUND

A protocol for the intensive treatment of non-cerebellar PNET (CNS-PNET) combining chemotherapy and radiotherapy was launched in 2000. Efforts were subsequently made to improve the prognosis and to de-escalate the treatment for selected patient groups.

PROCEDURE

Twenty-eight consecutive patients were enrolled for a high-dose drug schedule (methotrexate, etoposide, cyclophosphamide, and carboplatin ± vincristine), followed by hyperfractionated accelerated CSI (HART-CSI) at total doses of 31-39 Gy, depending on the patient's age, with two high-dose thiotepa courses following CSI. After the first 15 patients had been treated, craniospinal irradiation (CSI) was replaced with focal radiotherapy (RT) for selected cases (non-metastatic and not progressing during induction chemotherapy). Eight of the 28 children received the same chemotherapy but conventionally fractionated focal RT at 54 Gy.

RESULTS

The 5-year progression-free survival (PFS), event-free survival (EFS), and overall survival (OS) rates were 62%, 53%, and 52%, respectively, for the whole series, and 70%, 70%, and 87% for the eight focally irradiated children. Residual disease and metastases were not prognostically significant. In children with residual disease, response to RT was significant (5-year PFS 59% vs. 20%, P = 0.01), while the total dose of CSI was not. There were three treatment-related toxic events. Relapses were local in seven cases (including two of the eight focally irradiated patients), and both local and disseminated in 2.

CONCLUSIONS

This intensive schedule enabled treatment stratification for the purposes of radiation, thereby sparing some children full-dose CSI. Local control is the main goal of treatment for CNS-PNET.

Nutritional status is superior to the ECOG performance status in predicting the dose-intensity of the GEMOX chemotherapy regimen in patients with advanced cancer

The increasing number of unfit patients calls for better risk assessment prior to initiating anti-tumor treatment. This is a major concern in the prevention and reduction of treatment-related complications. The aim of our study was to evaluate the nutritional status for the risk assessment of patients qualifying to receive the gemcitabine and oxaliplatin (GEMOX) regimen. This single-center, retrospective study examined baseline clinical and biological characteristics in a cohort of 165 unselected, consecutive cancer patients receiving GEMOX. Malnutrition was defined as either body mass index (BMI) <18.5 kg/m(2), body weight loss >10% over 3 mo, or albuminemia <35 g/L. A total of 165 patients (median age 61 yr, PS 0-1: 71%) were studied. Malnutrition was seen in 43% of PS 0-1 patients, vs. 60% of PS 2 and 66% of PS 3 patients (P > 0.05). Median relative dose-intensity was 0.90 (0.17-1.04). GEMOX dose-intensity correlated negatively with loss of baseline weight (r = -0.24, P < 0.02). In patients who did not complete more than 2 cycles of chemotherapy, median PS (P < 0.01), mean C-reactive protein (CRP; P < 0.01), and mean albuminemia (P < 0.05) were, respectively, significantly higher, higher, and lower. Malnutrition is associated with a high risk of early discontinuance of treatment. Systematic basal evaluation of the nutritional status, including albuminemia and BMI, is recommended.

High-risk medulloblastoma: a pediatric oncology group randomized trial of chemotherapy before or after radiation therapy (POG 9031)

PURPOSE

To compare event-free survival (EFS) in children with high-risk medulloblastoma randomly assigned to receive either chemotherapy before radiation or chemotherapy after radiation.

PATIENTS AND METHODS

One hundred twelve patients were randomly assigned to each arm. Criteria used to categorize patients as high risk included M1-4 disease by modified Chang staging classification, T3b/T4 disease, or greater than 1.5 cm3 of residual tumor after surgery. Postoperatively, children with high-risk medulloblastoma were randomly assigned to two arms, either chemotherapy entailing three cycles of cisplatin and etoposide before radiation (chemotherapy first [CT1]) or the same chemotherapy regimen after radiation (radiation therapy first [RT1]). Both groups received consolidation chemotherapy consisting of vincristine and cyclophosphamide.

RESULTS

The median follow-up time was 6.4 years. Five-year EFS was 66.0% in the CT1 arm and 70.0% in the RT1 arm (P = .54), and 5-year overall survival in the two groups was 73.1% and 76.1%, respectively (P = .47). In the CT1 arm, 40 of the 62 patients with residual disease achieved either complete or partial remission.

CONCLUSION

Five-year EFS did not differ significantly whether, after surgery, patients received chemotherapy before or after radiotherapy.

Challenges and opportunities in childhood cancer drug development

Advances made in the treatment of childhood malignancies over the past four decades have resulted in overall 5-year survival rates of approximately 80%. However, despite these advances, several childhood cancers still have unacceptably low cure rates, and, even when treatment is successful, the acute and long-term morbidity of current therapy can be substantial. The development of molecularly targeted anticancer drugs offers the prospect of more effective therapy with fewer side effects, but will require increasing partnership between governments, and the academic and private sectors.

5-day/5-drug myeloablative outpatient regimen for resistant neuroblastoma

5-day/5-drug (5D/5D) is a novel high-dose regimen administered with autologous hematopoietic SCT (HSCT). It was designed to maximize cytoreduction via high dosing of synergistically interacting agents, while minimizing morbidity in patients with resistant neuroblastoma (NB) and ineligible for clinical trials due to myelosuppression from previous therapy. 5D/5D comprises carboplatin 500 mg/m(2)/day on days 1-2, irinotecan 50 mg/m(2)/day on days 1-3, temozolomide 250 mg/m(2)/day on days 1-3, etoposide 200 mg/m(2)/day on days 3-5 and cyclophosphamide 70 mg/kg/day on days 4-5. HSCT is on day 8. Sixteen patients received 21 courses. Treatment was in the outpatient clinic. Responses were noted against progressive disease (PD) that had developed while patients were off, or receiving only low-dose, chemotherapy but not against PD that emerged despite high-dose chemotherapy. Responses were also seen in patients with PD or stable disease after (131)I-metaiodobenzylguanidine therapy. Grade 3 toxicities were limited to transient elevations in liver enzymes (three courses) and hyponatremia (one course). Bacteremia occurred in 2/21 (10%) courses. Hematological recovery allowed patients to be enrolled on clinical trials. In conclusion, 5D/5D (including HSCT) spares vital organs, entails modest morbidity, shows activity against resistant NB and helps patients meet eligibility requirements for formal clinical trials.

Global gene expression profiling confirms the molecular fidelity of primary tumor-based orthotopic xenograft mouse models of medulloblastoma

We previously showed that primary tumor-based orthotopic xenograft mouse models of medulloblastoma replicated the histopathological phenotypes of patients' original tumors. Here, we performed global gene expression profiling of 11 patient-specific xenograft models to further determine whether the xenograft tumors were molecularly accurate during serial subtransplantations in mouse brains and whether they represented all the molecular subtypes of medulloblastoma that were recently described. Analysis of the transcriptomes of 9 pairs of matched passage I xenografts and patients' tumors revealed high correlation coefficients (r(2) > 0.95 in 5 models, > 0.9 in 3 models, and > 0.85 in 1 model) and only identified 69 genes in which expressions were altered (FDR = 0.0023). Subsequent pair-wise comparisons between passage I, III, and V xenografts from the 11 models further showed that no dramatic alterations were introduced (r(2) > 0.9 in 8 models and > 0.8 in 3 models). The genetic abnormalities of each model were then identified through comparison with control RNAs from 5 normal cerebella and 2 fetal brains. Hierarchical clustering using 3 previously published molecular signatures showed that our models span the whole spectrum of molecular subtypes, including SHH (n = 2), WNT (n = 2), and the most recently identified group C (n = 4) and group D (n = 3). In conclusion, we demonstrated that the 11 orthotopic medulloblastoma xenograft models were molecularly faithful to the primary tumors, and our comprehensive collection of molecularly distinct animal models should serve as a valuable resource for the development of new targeted therapies for medulloblastoma.

Neuropsychological Outcomes of Children Treated for Posterior Fossa Tumours:A Review

The posterior fossa region of the brain is a frequent site for tumour development in children, with over half of all childhood tumours occurring at this site. The principal brain structure implicated at this site is the cerebellum. Children treated for posterior fossa tumours can have a wide range of neurological and psychosocial problems. This paper describes the literature to date that addresses the neuropsychological impact of tumour and treatment in children with posterior fossa tumours. This paper reviews the literature on the causes of morbidity in this group. It discusses the recent research on the role of the cerebellum in outcomes and the studies that identify variables that interact with radiation effects.

Medulloblastomas: update on a heterogeneous disease

PURPOSE OF REVIEW

Medulloblastoma is the main primitive neuroectodermal tumour of the posterior fossa in childhood. The classical therapeutic approach consists of surgical resection, followed by craniospinal irradiation. Because of the good overall survival (75%), the main recent research efforts focus on refining the most relevant prognostic stratification and in decreasing the long-term sequelae.

RECENT FINDINGS

Thanks to the better understanding of the heterogeneity of medulloblastomas, clinical, histological and biological markers have been clearly identified and allow risk-adapted strategies. A subset of tumours of early childhood (<3-5 years), frequently associated with a Sonic Hedgehog signalling, might be cured without irradiation. In older children, several trials have demonstrated the safety of reduced craniospinal irradiation in standard risk tumours. Furthermore, the evidence of an excellent prognosis associated with a subset of tumours characterized by an activation of the WNT pathway leads to forthcoming de-escalating strategies. Reducing long-term sequelae also relies on new surgical approaches aiming at reducing the cerebellar injuries. Tremendous efforts have also been made in defining the most adapted irradiation doses and fields. Intensity-modulated radiotherapy and proton beam therapy might also influence the long-term neurological and endocrine defects of the patients.

SUMMARY

Histological and biological characteristics clearly define various prognostic groups within medulloblastomas; confirming the overall good outcome and reducing long-term sequelae are the main focus of current clinical trials.

Appraisal of the current staging system for residual medulloblastoma by volumetric analysis

AIM

This study aims to investigate the accuracy of the current staging system of childhood medulloblastoma by using volumetric image analysis on immediate post-operative MRI scans.

MATERIAL AND METHODS

Tumour volume and maximum cross area of residual medulloblastoma were measured on immediate post-operative MR scans of 37 children operated between 1999 and 2005.

RESULTS

Mean preoperative volume was 32 cm(3) (range 4.5-71.9 cm(3)). Mean post-operative volume was 3.3 cm(3) (range 0-23.3 cm(3)). At mean follow-up of 50.08 months (range 6-129), 15 (40%) patients had died. Cut-off limit for residual post-operative tumour volume employed was maximum cross section of 1.5 cm(2), which corresponds to volume of 1.376 cm(3); 14 patients (38%) had no residual tumour, 7 patients (19%) had less than 1.5 cm(2) and 16 patients (43%) had more than 1.5 cm(2) residual tumour in its maximum cross section area. In three patients (8.2%) there was mismatch between the measured maximum cross section area and volume. In particular, in two patients, the cross section areas were more than 1.5 cm(2) but the residual tumour volumes were less than 1.376 cm(3) (the cross section area overestimated the residual volume) and in one case, the cross section area was less than 1.5 cm(2) but the residual tumour volume was more than 1.376 cm(3) (the cross section area underestimated the residual volume; difference statistically significant, Fisher's exact test, p < 0.01).

CONCLUSIONS

It appears that volumetric measurement of residual medulloblastoma on immediate post-operative MRI scans may further improve the accuracy of staging process.

Convergence of normal stem cell and cancer stem cell developmental stage: Implication for differential therapies

Increased evidence shows that normal stem cells may contribute to cancer development and progression by acting as cancer-initiating cells through their interactions with abnormal environmental elements. We postulate that normal stem cells and cancer stem cells (CSC) possess similar mechanisms of self-renewal and differentiation. CSC can be the key to the elaboration of anti-cancer-based therapy. In this article, we focus on a controversial new theme relating to CSC. Tumorigenesis may have a critical stage characterized as a "therapeutic window", which can be identified by association of molecular, biochemical and biological events. Identifying such a stage can allow the production of more effective therapies (e.g. manipulated stem cells) to treat several cancers. More importantly, confirming the existence of a similar therapeutic window during the conversion of normal stem cells to malignant CSC may lead to targeted therapy specifically against CSC. This conversion information may be derived from investigating the biological behaviour of both normal stem cells and cancerous stem cells. Currently, there is little knowledge about the cellular and molecular mechanisms that govern the initiation and maintenance of CSC. Studies on co-evolution and interdependence of cancer with normal tissues may lead to a useful treatment paradigm of cancer. The crosstalk between normal stem cells and cancer formation may converge developmental stages of different types of stem cells (e.g. normal stem cells, CSC and embryonic stem cells). The differential studies of the convergence may result in novel therapies for treating cancers.

Phase I study of tandem high-dose chemotherapy with autologous peripheral blood stem cell rescue for children with recurrent brain tumors: a Pediatric Blood and MarrowTransplant Consortium study

BACKGROUND

High-dose chemotherapy with autologous stem cell rescue (HDC/SCR) has produced responses and prolonged survival for some children with recurrent brain tumors, but is associated with considerable morbidity and mortality. A Phase I trial of two cycles of HDC/SCR for recurrent brain tumors in children was performed to determine the maximum tolerated doses for a novel regimen.

PROCEDURES

Two cycles of HDC/SCR were given. Cycle 1 included thiotepa and carmustine given on days -5, -4, and -3. Four to six weeks later, patients received cycle 2 which included thiotepa and carboplatin given on days -5, -4, and -3. Autologous peripheral blood stem cells (PBSC) were infused on day 0 of each cycle.

RESULTS

Thirty-two patients were treated and 25 patients received both cycles of HDC/SCR. Common toxicities included mucositis, emesis, diarrhea, anorexia, and pancytopenia. Eight of 32 (25%) assessable children died from regimen-related toxicity. Pulmonary failure occurred in seven patients. Seven patients had grade 3-4 neurotoxicity. The 3-year event-free survival (EFS) was 25%.

CONCLUSIONS

We determined the maximum tolerated regimen to be thiotepa 600 mg/m(2) and carmustine 300 mg/m(2) followed by thiotepa 600 mg/m(2) and carboplatin 1,200 mg/m(2) . Pulmonary toxicity was considerable. The toxic death rate was similar to other trials of HDC/SCR for children with recurrent brain tumors performed during the same time period. The regimen resulted in prolonged time to progression for a significant number of patients and long-term survival for some patients with recurrent medulloblastoma and rhabdoid tumor.

Childhood medulloblastoma

Among all the childhood central nervous system tumours, medulloblastoma and other neuroectodermal tumours account for 16-25% of cases. The causative factors of medulloblastoma/PNET have not been well established. It is more frequent in boys than in girl and in children than in adults. There was a significant improvement of survival for children diagnosed in 2000-2002 compared to those diagnosed in 1995-1999. The risk of dying was reduced by 30%. Patients are generally divided into risk-stratified schemes on the basis of age, the extent of residual disease, and dissemination. Sixty to 70% of patients older than 3 years are assigned to the average-risk group. High-risk patients include those in the disseminated category, and in North American trials those that have less than a gross or near-total resection, which is arbitrarily defined as 1.5 cm(2) of post-operative residual disease. Current and currently planned clinical trials will:define molecular and biological markers that improve outcome prediction in patients with medulloblastoma and which can be incorporated for front-line stratification of newly defined risk subgroups.

Successful treatment of trilateral retinoblastoma with conventional and high-dose chemotherapy plus radiotherapy: a case report

Trilateral retinoblastoma (TRB) is a rare condition characterized by an intracranial neuroblastic tumor associated with bilateral or unilateral retinoblastoma (RB). The outcome is almost always fatal. An 18-month-old patient with familial bilateral RB was referred for a pineal lesion detected on a screening by magnetic resonance imaging. The child, considered inoperable by 2 different neurosurgical teams, was treated with conventional chemotherapy (methotrexate, vincristine, vepeside, cyclophosphamide, and carboplatin) plus tandem transplantation (vepeside/carboplatin and thiotepa/mephalan) followed by local radiotherapy. At 80 months from the diagnosis of TRB, the patient is alive and in complete remission, with no neuropsychologic consequences. An early and aggressive treatment may improve the prognosis of TRB.

Reduced-dose craniospinal radiotherapy followed by high-dose chemotherapy and autologous stem cell rescue for children with newly diagnosed high-risk medulloblastoma or supratentorial primitive neuroectodermal tumor

Background

In this study, we investigated the effects of reduced-dose craniospinal radiotherapy (CSRT) followed by tandem high-dose chemotherapy (HDCT) with autologous stem cell rescue (ASCR) in children with a newly diagnosed high-risk medulloblastoma (MB) or supratentorial primitive neuroectodermal tumor (sPNET).

Methods

Between March 2005 and April 2007, patients older than 3 years with a newly diagnosed high-risk MB or sPNET were enrolled. The patients received two cycles of pre-RT chemotherapy consisting of cisplatin, etoposide, vincristine, and cyclophosphamide (cycle A), and carboplatin, etoposide, vincristine, and ifosphamide (cycle B), followed by CSRT with 23.4 Gy and local RT with 30.6 Gy. After four cycles of post-RT chemotherapy (cycles A, B, A, and B), tandem double HDCT with ASCR was performed.

Results

A total of 13 patients (MB=11, sPNET=2) were enrolled. Of these, one patient progressed, one patient died of septic shock after the second cycle of B, and one patient relapsed after the third cycle of B. The 3-year event-free survival (EFS) rate of the patients intended for HDCT was 76.9%, whereas the 3-year EFS rate of the patients who received HDCT was 100%. No treatment-related mortality occurred during HDCT.

Conclusion

Although the follow-up period was short and the patient cohort was small in size, the results of this study are encouraging. The limited toxicity and favorable EFS rate observed in children treated with reduced-dose CSRT followed by HDCT and ASCR warrant further exploration in a larger study population.

Successful mobilization, harvest and transplant of peripheral blood stem cells using AMD3100 and G-CSF following high dose craniospinal irradiation for medulloblastoma in a young child

Contemporary protocols for the treatment of malignant brain tumors such as medulloblastoma (MB) in children, often involve craniospinal irradiation (CSI) at diagnosis followed by serial courses of high dose chemotherapy and autologous hematopoietic stem cell support. Patients often require several pheresis procedures in order to collect sufficient stem cells for this type of treatment, particularly if they have already had CSI. We describe the successful mobilization, collection and subsequent transplant of a 7-year-old female with medulloblastoma after recent CSI using granulocyte colony stimulating factor (G-CSF) and the CXCR4 antagonist AMD3100 after a failed previous mobilization attempt using G-CSF alone.

Childhood medulloblastoma: current status of biology and treatment

Medulloblastoma, a primitive neuro-ectodermal tumour that arises in the posterior fossa, is the most common malignant brain tumour occurring in childhood. Over the past half century, the long-term survival for children with medulloblastoma has improved remarkably from a certain fatal diagnosis to a cancer that is often curable. Although overall survival for children with non-disseminated and non-anaplastic medulloblastoma can approach 80%, the current multidisciplinary therapeutic approach is not without long-term sequelae. Chemotherapy has improved the long-term survival and allowed for reductions in the amount of radiation given, thereby reducing some of the long-term toxicities. In this review, we describe the current understanding of the basic biology of medulloblastoma and report on the current active chemotherapeutic agents utilized in medulloblastoma therapy. Ultimately, our understanding of the basic biology of medulloblastoma may lead to further advances in therapy by providing targets that are more specific and potentially less toxic.

Feasibility of sequential high-dose chemotherapy in advanced pediatric solid tumors

The purpose of this study was to evaluate the feasibility and tumor response of 3 cycles of sequential high-dose chemotherapy (HDCT) in advanced pediatric solid tumor patients. Medical records of 11 children who underwent 2 consequent courses of reduced conditioning HDCT followed by final HDCT with autologous HSC infusion were reviewed in a retrospective manner. Each median time to an absolute neutrophil count > 0.5 x 10(9)/L was 12, 13, and 12 days. Major toxic reactions were fever, infection, and vomiting. One patient experienced transplantation-related mortality. Nine patients showed complete and partial responses to the therapy at 6 months follow-up after final HDCT. Finally, 6 patients are alive without evidence of disease at median follow-up of 24 months. Even though it is a preliminary result, the authors think that this treatment could be a feasible treatment option for advanced pediatric solid tumor patients.

Pediatric brain tumors: current treatment strategies and future therapeutic approaches

Pediatric CNS tumors are the most common solid tumors of childhood and the second most common cancer after hematological malignancies accounting for approximate 20 to 25% of all primary pediatric tumors. With over 3,000 new cases per year in the United States, childhood CNS tumors are the leading cause of death related to cancer in this population. The prognosis for these patients has improved over the last few decades, but current therapies continue to carry a high risk of significant side effects, especially for the very young. Currently a combination of surgery, radiation, and chemotherapy is often used in children greater than 3 years of age. This article will outline current and future therapeutic strategies for the most common pediatric CNS tumors, including primitive neuroectodermal tumors such as medulloblastoma, as well as astrocytomas and ependymomas.

Hyperfractionated Accelerated Radiotherapy in the Milan Strategy for Metastatic Medulloblastoma

Purpose

With a view to improving the prognosis for patients with metastatic medulloblastoma, we tested the efficacy and toxicity of a hyperfractionated accelerated radiotherapy (HART) regimen delivered after intensive sequential chemotherapy.

Patients and Methods

Between 1998 and 2007, 33 consecutive patients received postoperative methotrexate (8 g/m2), etoposide (2.4 g/m2), cyclophosphamide (4 g/m2), and carboplatin (0.8 g/m2) in a 2-month schedule, then HART with a maximal dose to the neuraxis of 39 Gy (1.3 Gy/fraction, 2 fractions/d) and a posterior fossa boost up to 60 Gy (1.5 Gy/fraction,2 fractions/d). Patients with persistent disseminated disease before HART were consolidated with two myeloablative courses and circulating progenitor cell rescue.

Results

Patients were classified as having M1 (n = 9), M2 (n = 6), M3 (n = 17), and M4 (n = 1) disease. Seven patients younger than 10 years old who achieved complete response after chemotherapy received a lower dose to the neuraxis (31.2 Gy). Twenty-two of the 32 assessable patients responded to chemotherapy; disease was stable in five patients and progressed in five patients. One septic death occurred before radiotherapy. Eight patients experienced relapse after a median of 12 months. Fourteen of the 33 patients underwent consolidation therapy after HART. With a median 82-month survivor follow-up, the 5-year event-free, progression-free, and overall survival rates were 70%, 72%, and 73%, respectively. No severe clinical complications of HART have emerged so far.

Conclusion

HART after intensive postoperative chemotherapy, followed by myeloablative chemotherapy in selected cases, proved feasible in children with metastatic medulloblastoma. The results of our treatment compare favorably with other series treated using conventional therapies.

Changes mimicking new leptomeningeal disease after intensity-modulated radiotherapy for medulloblastoma

PURPOSE

Acute and late changes in magnetic resonance imaging of the pediatric brain have been described after radiotherapy (RT). We report the post-RT neuroimaging changes in the posterior fossa after intensity-modulated RT (IMRT) in children with medulloblastoma and contrast them with those of leptomeningeal disease.

METHODS AND MATERIALS

We performed a retrospective review of 53 consecutive children with medulloblastoma who were treated with craniospinal RT followed by IMRT to the posterior fossa and chemotherapy between 1997 and 2006.

RESULTS

After IMRT to the posterior fossa, 8 (15%) of 53 patients developed increased fluid-attenuated inversion-recovery signal changes in the brainstem or cerebellum and patchy, multifocal, nodular contrast enhancement at a median of 6 months. The enhancement superficially resembled leptomeningeal disease. However, the enhancement resolved without intervention at a median of 6 months later. The accompanying fluid-attenuated inversion-recovery signal changes occasionally preceded the enhancement, were often parenchymal in location, and resolved or persisted to a lesser degree. All 8 patients with transient magnetic resonance imaging changes in the posterior fossa were alive at last follow-up. In contrast, leptomeningeal disease occurred in 8 (15%) of our 53 patients at a median of 19.5 months after IMRT completion. Of these 8 patients, 7 demonstrated initial nodular enhancement outside the conformal field, and 7 patients died.

CONCLUSION

Magnetic resonance imaging changes can occur in the posterior fossa of children treated with IMRT for medulloblastoma. In our experience, these transient changes occur at a characteristic time and location after RT, allowing them to be distinguished from leptomeningeal disease.

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.

Medulloblastoma: what is the role of molecular genetics?

Among pediatric malignancies, medulloblastoma (MB) is one of the most common malignant tumors of the CNS. In the past few years, thanks to a multidisciplinary approach including surgery, chemo- and radiation therapy, survival has significantly improved. Despite that, a third of patients still have a low chance of being cured and long-term survivors experience severe treatment-related sequelae. MBs are usually classified according to a clinical risk stratification, based on histological features, age at diagnosis, extent of tumor resection and presence or absence of metastases. However, these clinical variables have recently been reported to be poor for defining risk-related disease. Retrospective studies have identified histological or biological factors that have distinct roles in prognosis. As several pathways have been discovered to be involved in MB pathogenesis, they should be taken into account to more accurately stratify patients and their treatment and to develop innovative therapies.

Amifostine protects against cisplatin-induced ototoxicity in children with average-risk medulloblastoma

PURPOSE

To determine the role of amifostine as a protectant against cisplatin-induced ototoxicity in patients with average-risk (AR) medulloblastoma treated with craniospinal radiotherapy and four cycles of cisplatin-based, dose-intense chemotherapy and stem-cell rescue.

PATIENTS AND METHODS

The primary objective was to determine whether, in patients with AR medulloblastoma (n = 62), amifostine would decrease the need for hearing aids (defined as >or= grade 3 ototoxicity in one ear) compared with a control group (n = 35), 1 year from initiating treatment. Ninety-seven patients received craniospinal irradiation (23.4 Gy) followed by 55.8 Gy to the primary tumor bed using three-dimensional conformal technique, and four cycles of high-dose cyclophosphamide (4,000 mg/m(2)/cycle), cisplatin (75 mg/m(2)/cycle), and vincristine (two 1.5 mg/m(2) doses/cycle) and stem-cell rescue. When used, amifostine (600 mg/m(2)/dose) was administered as a bolus immediately before and 3 hours into the cisplatin infusion.

RESULTS

The median age of the 97 patients was 8.7 years (range, 3.2 to 20.2 years). The study and control groups were similar in age and sex distribution. Amifostine was well-tolerated. One year after treatment initiation, 13 patients (37.1%) in the control group versus nine (14.5%; one-sided chi(2) test P = .005) of the amifostine-treated patients had at least grade 3 ototoxicity, requiring hearing aid in at least one ear.

CONCLUSION

Amifostine administered before and during the cisplatin infusion can significantly reduce the risk of severe ototoxicity in patients with AR medulloblastoma receiving dose-intense chemotherapy.

Multi-institution prospective trial of reduced-dose craniospinal irradiation (23.4 Gy) followed by conformal posterior fossa (36 Gy) and primary site irradiation (55.8 Gy) and dose-intensive chemotherapy for average-risk medulloblastoma

PURPOSE

Limiting the neurocognitive sequelae of radiotherapy (RT) has been an objective in the treatment of medulloblastoma. Conformal RT to less than the entire posterior fossa (PF) after craniospinal irradiation might reduce neurocognitive sequelae and requires evaluation.

METHODS AND MATERIALS

Between October 1996 and August 2003, 86 patients, 3-21 years of age, with newly diagnosed, average-risk medulloblastoma were treated in a prospective, institutional review board-approved, multi-institution trial of risk-adapted RT and dose-intensive chemotherapy. RT began within 28 days of definitive surgery and consisted of craniospinal irradiation (23.4 Gy), conformal PF RT (36.0 Gy), and primary site RT (55.8 Gy). The planning target volume for the primary site included the postoperative tumor bed surrounded by an anatomically confined margin of 2 cm that was then expanded with a geometric margin of 0.3-0.5 cm. Chemotherapy was initiated 6 weeks after RT and included four cycles of high-dose cyclophosphamide, cisplatin, and vincristine.

RESULTS

At a median follow-up of 61.2 months (range, 5.2-115.0 months), the estimated 5-year event-free survival and cumulative incidence of PF failure rate was 83.0% +/- 5.3% and 4.9% +/- 2.4% (+/- standard error), respectively. The targeting guidelines used in this study resulted in a mean reduction of 13% in the volume of the PF receiving doses >55 Gy compared with conventionally planned RT. The reductions in the dose to the temporal lobes, cochleae, and hypothalamus were statistically significant.

CONCLUSION

This prospective trial has demonstrated that irradiation of less than the entire PF after 23.4 Gy craniospinal irradiation for average-risk medulloblastoma results in disease control comparable to that after treatment of the entire PF.

Medulloblastoma: from molecular pathology to therapy

Medulloblastoma is the most common malignant tumor of central nervous system in children. Patients affected by medulloblastoma may be categorized as high-risk and standard-risk patients, based on the clinical criteria and histologic features of the disease. Currently, multimodality treatment, including surgery, radiotherapy, and chemotherapy is considered as the most effective strategy against these malignant cerebellar tumors of the childhood. Despite the potential poor outcomes of these lesions, the 5-year survival stands, at present, at 70% to 80% for standard-risk patients, whereas high-risk patients have a 5-year survival of 55% to 76%. Attempts to further reduce the morbidity and mortality associated with medulloblastoma have been restricted by the toxicity of conventional treatments and the infiltrative nature of the disease. Over the past decade, new discoveries in molecular biology have revealed new insights in signaling pathways regulating medulloblastoma tumor formation. Recent advances in the molecular biology of medulloblastoma indicate that the classification of these embryonal tumors, solely based on histology and clinical criteria, may not be adequate enough. Better understanding of the growth control mechanisms involved in the development and progression of medulloblastoma will allow a better classification, leading to the improvement of the existing therapies, as well as to the development of new therapeutic approaches.

Medulloblastoma in childhood: new biological advances

Medulloblastoma is the most common embryonal tumour in children. Patients with medulloblastoma are currently staged as average-risk or poor-risk on the basis of clinical findings. With current multimodality therapy, nearly 90% of children with average-risk, non-disseminated medulloblastoma have 5-year event-free survival, and those with high-risk disease have a 60-65% survival rate; however, the outcome for younger children, particularly infants, is worse. Children who survive medulloblastoma are at risk of long-term sequelae related to the neurological effects of the tumour, surgery, or radiotherapy, and the additive effects of chemotherapy. Molecular biology has changed our understanding of medulloblastoma and has implications for diagnostic stratification and treatment. As newer biological agents are translated from the lab to the bedside, clinicians need to understand the fundamental signalling pathways that are targeted during therapy. Greater understanding of the molecular biology of medulloblastoma is needed so that more children can be cured or have an improved quality of life.

Multiple factors contribute to neuropsychological outcome in children with posterior fossa tumors

Cognitive deficits are frequently reported in children treated for posterior fossa (PF) tumors. A range of tumor, treatment, medical and treatment complications have been implicated in causing a variety of cognitive deficits. The aim of this study is to identify factors that influence intelligence, attention and information processing in these children. Thirty-five children (aged 4-16) with PF tumors attending the Royal Children's Hospital Melbourne, Australia, were enrolled into a prospective, repeated measures design. Neuropsychological assessments were conducted at diagnosis and at 12 month intervals for three years. The results find that the PF tumor, hydrocephalus, white matter injury and radiation therapy have various impacts on intelligence, attention and information processing skills, and contribute to the long term outcome in children treated for PF tumor. The neurological structures that subserve the efficient function of attention and information processing are particularly vulnerable to those factors.

Overexpressed TP73 induces apoptosis in medulloblastoma

Background

Medulloblastoma is the most common malignant brain tumor of childhood. Children who relapse usually die of their disease, which reflects resistance to radiation and/or chemotherapy. Improvements in outcome require a better understanding of the molecular basis of medulloblastoma growth and treatment response. TP73 is a member of the TP53 tumor suppressor gene family that has been found to be overexpressed in a variety of tumors and mediates apoptotic responses to genotoxic stress. In this study, we assessed expression of TP73 RNA species in patient tumor specimens and in medulloblastoma cell lines, and manipulated expression of full-length TAp73 and amino-terminal truncated ΔNp73 to assess their effects on growth.

Methods

We analyzed medulloblastoma samples from thirty-four pediatric patients and the established medulloblastoma cell lines, Daoy and D283MED, for expression of TP73 RNA including the full-length transcript and the 5'-terminal variants that encode the ΔNp73 isoform, as well as TP53 RNA using quantitative real time-RTPCR. Protein expression of TAp73 and ΔNp73 was quantitated with immunoblotting methods. Clinical outcome was analyzed based on TP73 RNA and p53 protein expression. To determine effects of overexpression or knock-down of TAp73 and ΔNp73 on cell cycle and apoptosis, we analyzed transiently transfected medulloblastoma cell lines with flow cytometric and TUNEL methods.

Results

Patient medulloblastoma samples and cell lines expressed full-length and 5'-terminal variant TP73 RNA species in 100-fold excess compared to non-neoplastic brain controls. Western immunoblot analysis confirmed their elevated levels of TAp73 and amino-terminal truncated ΔNp73 proteins. Kaplan-Meier analysis revealed trends toward favorable overall and progression-free survival of patients whose tumors display TAp73 RNA overexpression. Overexpression of TAp73 or ΔNp73 induced apoptosis under basal growth conditions in vitro and sensitized them to cell death in response to chemotherapeutic agents.

Conclusion

These results indicate that primary medulloblastomas express significant levels of TP73 isoforms, and suggest that they can modulate the survival and genotoxic responsiveness of medulloblastomas cells.