P11.60 Neurosurgical delivery of the poly ADP ribose polymerase-1 inhibitor olaparib from a thermo-responsive biodegradable paste potentiates radiotherapy and prolongs survival

BACKGROUND

There has been considerable interest in repurposing the poly ADP ribose polymerase inhibitor and purported radiosensitiser olaparib (Lynparza), with a recent dose escalation study of olaparib plus temozolomide in recurrent GBM showing good tolerance. Due to systemic therapy-associated caveats such as dose-limiting toxicities and blood-brain-barrier penetration, here we assess localised post-surgical delivery of olaparib from our previously developed PLGA/PEG thermo-sensitive biodegradable paste.

MATERIAL AND METHODS

Metabolic and clonogenic assays were used to assess effects on proliferation and clonal growth upon in vitro glioma exposure to olaparib. Flow cytometry and Annexin V/Propidium iodide were used to determine apoptosis. The 9L high-grade glioma orthotopic allograft model was utilised to assess survival upon intra-cavity olaparib delivery.

RESULTS

Metabolic and clonogenic assays revealed impaired proliferation and clonal growth respectively, upon acute exposure of high-grade glioma cells to olaparib (3–5µM), an effect dramatically potentiated with 3Gy radiation. Flow cytometry of Annexin V+/Propidium iodide+ rodent and human high-grade glioma cells, revealed a significant cell proportion increase at late stage apoptosis when exposed to 2–3µM olaparib and 3Gy radiation (relative to untreated, olaparib alone or radiation alone). A high-grade glioma orthotopic allograft study revealed a significant overall survival benefit of locally-delivered 10% and 20% w/w (drug:polymer ratio) olaparib via PLGA/PEG paste post-surgery with adjuvant radiotherapy, compared to surgery/oral temozolomide/radiotherapy (GBM standard-of-care) and surgery/systemic olaparib (95 vs. 44 vs. 30 days respectively). A more pronounced survival benefit, as measured by number of animals surviving long-term, was observed with combined PLGA/PEG/olaparib/temozolomide/radiotherapy or PLGA/PEG/olaparib/etoposide/radiotherapy, relative to standard-of-care (95 vs. 44 days). Clinical correlation was determined using RNAseq data from 10 GBM patients, showing significantly elevated levels of apoptosis-inducing factor-1 in 5-aminolevulinic acid (5ALA)+ fluorescence-activated cell sorted populations (i.e. purified tumour cells from the invasive margin), relative to 5ALA- cells, confirming PARP-1 activity in infiltrative tumour cells.

CONCLUSION

Collectively our data supports a clinical rationale for localised olaparib delivery with adjuvant radiotherapy.

P11.62 Brain distribution models to select polymer-delivered drugs for the intra-cavity treatment of malignant glioma

BACKGROUND

Conventional oral or intravenous chemotherapy distributes drugs to the whole body whereby systemic toxicity to healthy parts of the body (e.g. bone marrow failure) limits the maximum dose that can be achieved in the brain. This presents a particular concern for CNS tumours where the blood-brain-barrier (BBB) restricts drug influx from the circulation. The ability to deliver chemotherapy locally at the tumour site offers the opportunity to target residual cancer cells post-surgery whilst minimising systemic toxicity. We have developed a poly(lactic-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) polymer matrix that forms a porous paste at room temperature when mixed with chemotherapy-containing saline, solidifying only at body temperature, with close apposition to the irregular surgical cavity. It is important that we can observe whether the drugs released from PLGA/PEG can penetrate brain parenchyma beyond the surgical resection margin at therapeutic doses. Currently the only way to measure the distribution of drugs in the body is to inject radioactive drugs into an animal. We aim to establish drug distribution parameters using label-free mass spectrometry imaging methods, prior to selection of drug formulations for clinically-relevant in vivo models. Drugs that penetrate the brain the furthest will be identified as good candidates for localised brain cancer drug delivery using PLGA/PEG paste.

MATERIAL AND METHODS

Diffusion rates were measured by examining the proportion of olaparib, dasatnib, carboplatin, etoposide, paclitaxel and gemcitabine at 2mg/ml concentration, which passes through 1mm slices of rat brain tissue within Franz cell chambers over a 6 hour period. The spatio-temporal distribution of label-free olaparib and dasatinib within mouse brain homogenate was quantitatively measured using innovative 3D OrbiSIMS, a hybrid time-of-flight / OrbitrapTM secondary ion mass spectrometer.

RESULTS

Within the Franz cell model, carboplatin and gemcitabine showed the highest diffusion rate diffusion at 16.4 and 6.53 µg/cm2/h respectively whereas olaparib, etoposide and paclitaxel were relatively poorly diffused at 1.87, 3.82 and 2.27 µg/cm2/h respectively. The minimum threshold of OrbiSIMS detection for label-free olaparib and dasatinib ions was 0.025 mg/ml and 0.2 mg/ml respectively throughout brain homogenate.

CONCLUSION

This study demonstrates different diffusion rates through brain tissue, between label-free chemotherapy drugs of distinct chemistries, with highest diffusion rates observed for carboplatin and gemcitabine. We also demonstrate label-free detection of olaparib and dasatinib using the innovative 3D OrbiSIMS method. These models will facilitate the rapid identification of agents most amenable for localised biomaterial-based chemotherapy delivery with high brain penetrance.

The European Society of Paediatric Oncology Ependymoma-II program Core-Plus model: Development and initial implementation of a cognitive test protocol for an international brain tumour trial

It is increasingly accepted that survival alone is an inadequate measure of the success of childhood brain tumour treatments. Consequently, there is growing emphasis on capturing quality of survival. Ependymomas are the third most frequently occurring brain tumours in childhood and present significant clinical challenges. European Society of Paediatric Oncology Ependymoma II is a comprehensive international program aiming to evaluate outcomes under different treatment regimens and improve diagnostic accuracy. Importantly, there has been agreement to lower the age at which children with posterior fossa ependymoma undergo focal irradiation from three years to either eighteen months or one year of age. Hitherto radiotherapy in Europe had been reserved for children over three years due to concerns over adverse cognitive outcomes following irradiation of the developing brain. There is therefore a duty of care to include longitudinal cognitive follow-up and this has been agreed as an essential trial outcome. Discussions between representatives of 18 participating European countries over 10 years have yielded European consensus for an internationally accepted test battery for follow-up of childhood ependymoma survivors. The 'Core-Plus' model incorporates a two-tier approach to assessment by specifying core tests to establish a minimum dataset where resources are limited, whilst maintaining scope for comprehensive assessment where feasible. The challenges leading to the development of the Core-Plus model are presented alongside learning from the initial stages of the trial. We propose that this model could provide a solution for future international trials addressing both childhood brain tumours and other conditions associated with cognitive morbidity.

A comprehensive view of the structure and expression of the ependymoma genome at presentation and relapse

2073

Background: Although pediatric and adult ependymomas are associated with significant mortality and morbidity, little is known about the biology of these tumors. To identify underlying genetic alterations and cellular pathways that drive this disease, we conducted a genomic study of 200 adult and pediatric ependymomas. Methods: Using 500k single nucleotide polymorphism arrays, U133 Affymetrix gene and microRNA (miRNA) expression microarrays, and appropriate bioinformatics, we characterized 56 supratentorial (ST), 104 posterior fossa (PF), and 40 spinal (SP) ependymomas. Real-Time polymerase chain reaction and fluorescence in situ hybridization validated observed genetic events. Results: Gene expression profiles segregated tumors by site and identified disease subgroups within each anatomical region (4 ST, 4 PF, 1 SP). miRNA expression profiles identified these same subgroups, indicating that they are biologically distinct. Subgroup-specific gene expression profiles were dictated partly by developmental regulatory genes and partly by large chromosomal gains (eg. 1q, 5p, 16p) and losses (eg. 9p, 22q). Integrated genetic and expression mapping revealed key candidate tumor suppressor (TSG) and onco- genes, likely drivers of these large alterations. While large chromosomal changes occurred more frequently in SP tumors (p < 0.0001), ST tumors averaged more focal changes (n = 13.2) than PF (n = 6.2) or SP tumors (n = 3.0) (p < 0.0001). A total of 29 and 33 non-random focal amplifications and deletions, respectively, encompassing 402 known genes and miRNA clusters, were validated, of which 80 displayed copy number driven expression. These genetic alterations targeted specific cellular functions (e.g., cell adhesion, cell-cycle, neuronal development) and pathways (e.g., NOTCH, EPHRIN, TP53). Our cohort also included five sample sets consisting of primary tumor and at least two corresponding relapses. Genomic analysis of these tumors identified large chromosomal alterations as well as focal gains and losses associated with disease relapse. Conclusions: We present a highly comprehensive view of the ependymoma genome, including 80 previously unrecognized candidate TSG and oncogenes that may afford diagnostic and therapeutic targets.

No significant financial relationships to disclose.

Intrathecal chemotherapy delivered by a lumbar-thecal catheter in metastatic medulloblastoma: a case illustration

BACKGROUND

Medulloblastoma is the most common malignant brain tumour in children. Despite recent advances, the prognosis in high risk patients remains poor. Further improvement in survival is dependent upon the development of strategies to attack the tumour more effectively, but with less toxicity. Intrathecal chemotherapy, is an ideal but currently underused method of directly targeting residual tumour within the area of resection and the leptomeningeal disease commonly associated with this tumour.

METHOD

We describe the case of a 12 yr old child with metastatic medulloblastoma, who received intrathecal topotecan via a spinal catheter.

CONCLUSION

This method represents a simple, safe and effective method of delivering an even and widespread distribution of drug within the cerebrospinal fluid (CSF) of the neuroaxis. With new agents being identified and others in the early stages of development, intrathecal chemotherapy may emerge as an important therapeutic option to consider when faced with such challenging cases.

Down-regulation of ATM protein in HRS cells of nodular sclerosis Hodgkin's lymphoma in children occurs in the absence ofATMgene inactivation

The tumour component of classical Hodgkin's lymphoma (cHL), Hodgkin Reed-Sternberg (HRS) cells, are believed to be derived from germinal centre (GC) B cells but intriguingly display a characteristic loss of B cell receptor (BCR) expression. The precise mechanisms by which BCR-negative HRS cell progenitors survive negative selection during the GC reaction remain obscure. Individuals with ataxia telangiectasia, caused by biallelic inactivation of the DNA damage response gene, ataxia telangiectasia mutated (ATM), have a higher risk of cHL development. Here we show that, in contrast to normal GC B cells that expressed low but detectable ATM protein, ATM protein was not detected in HRS cells of 17/18 cases of paediatric cHL, all but one with nodular sclerosis (NS) subtype. A comprehensive analysis of the ATM gene in microdissected HRS cells of nine representative tumours showed no evidence of either loss of heterozygosity or consistent pathogenic mutations. Furthermore, bisulphite sequencing of the ATM promoter from HRS cells of five tumours also revealed the absence of hypermethylation. Since our microarray data suggested significantly reduced ATM transcription in HRS cells compared to GC B cells, we conclude that loss of ATM expression could be the result of alterations in upstream regulators of ATM transcription. Importantly, ATM loss in paediatric cHLs has clinical implications and could be potentially exploited to guide future, less toxic, tumour-specific treatments.

Outcome of children with posterior fossa medulloblastoma: a single institution experience over the decade 1994-2003

AIM

While the impact of radiotherapy in the management of medulloblastoma was recognised, the introduction of chemotherapy was investigated in clinical trials and shown to confer an additional advantage. We reviewed the outcome of a series of consecutive patients to assess the impact in a population-based clinical establishment.

MATERIALS AND METHODS

A series of 38 children treated for medulloblastoma at Birmingham Children's Hospital between 1994 and 2003 was analysed. The effect of surgery, radiotherapy, chemotherapy and metastasis on survival was analysed.

RESULTS

The overall 5-year survival rate was 61.4% for the 36 patients who had resective surgery, while 2 patients had biopsy only and died within a few months. There was no operative mortality. The incidence of hydrocephalus needing permanent shunting was higher in the first 3 years of life (p = 0.007, chi-square). The 5-year survival rate of patients with total and sub-total excision of medulloblastoma was 61.1% and 61.8%, respectively. The 5-year survival rate of patients older than 3 years was 73.4% and for patients under 3 years was 36.3% (p = 0.007, log rank). Metastases at presentation did not influence survival. All deaths occurred in the first 32 months.

CONCLUSION

The contribution of chemotherapy in the improvement of the overall survival appears more evident in children younger than 3 years or presenting with metastases. The absence of significant difference in survival between patients with total or sub-total excision of medulloblastoma supports the view that total excision of medulloblastoma can be avoided when the risk for potential intra-operative damage and consequent neurological deficits is high.

Recurrent mesenchymal hamartoma associated with 19q translocation. A call for more radical surgical resection

Hepatic mesenchymal hamartoma is a rare benign tumour in children. It is often large and centrally located in the liver at diagnosis, making surgical resection difficult; thus non-radical resection has been proposed in the past as acceptable management. However, a literature survey and a case with recurrence associated with cytogenetic anomalies suggest that radical liver surgery (resection with a margin of normal liver parenchyma, as for malignant tumour) should be recommended for mesenchymal hamartoma.

Epigenetic alteration at the DLK1-GTL2 imprinted domain in human neoplasia: analysis of neuroblastoma, phaeochromocytoma and Wilms' tumour

Epigenetic alterations in the 11p15.5 imprinted gene cluster are frequent in human cancers and are associated with disordered imprinting of insulin-like growth factor (IGF)2 and H19. Recently, an imprinted gene cluster at 14q32 has been defined and includes two closely linked but reciprocally imprinted genes, DLK1 and GTL2, that have similarities to IGF2 and H19, respectively. Both GTL2 and H19 are maternally expressed RNAs with no protein product and display paternal allele promoter region methylation, and DLK1 and IGF2 are both paternally expressed. To determine whether methylation alterations within the 14q32 imprinted domain occur in human tumorigenesis, we investigated the status of the GTL2 promoter differentially methylated region (DMR) in 20 neuroblastoma tumours, 20 phaeochromocytomas and, 40 Wilms' tumours. Hypermethylation of the GTL2 promoter DMR was detected in 25% of neuroblastomas, 10% of phaeochromocytoma and 2.5% of Wilms' tumours. Tumours with GTL2 promoter DMR hypermethylation also demonstrated hypermethylation at an upstream intergenic DMR thought to represent a germline imprinting control element. Analysis of neuroblastoma cell lines revealed that GTL2 DMR hypermethylation was associated with transcriptional repression of GTL2. These epigenetic findings are similar to those reported in Wilms' tumours in which H19 repression and DMR hypermethylation is associated with loss of imprinting (LOI, biallelic expression) of IGF2. However, a neuroblastoma cell line with hypermethylation of the GTL2 promoter and intergenic DMR did not show LOI of DLK1 and although treatment with a demethylating agent restored GTL2 expression and reduced DLK1 expression. As described for IGF2/H19, epigenetic changes at DLK1/GTL2 occur in human cancers. However, these changes are not associated with DLK1 LOI highlighting differences in the imprinting control mechanisms operating in the IGF2-H19 and DLK1-GTL2 domains. GTL2 promoter and intergenic DMR hypermethylation is associated with the loss of GTL2 expression and this may contribute to tumorigenesis in a subset of human cancers.

Clear cell sarcoma: a dilemma on pathological staging and clinical management

Clear cell sarcoma of the kidney (CCSK) has been classified as high risk tumour in the previous UK and international Wilms tumor studies. The current Society of Paediatric Oncology (SIOP) trial, UK version, advocates chemotherapy including doxorubicin prior to nephrectomy. Pathological staging and histology of the resected tumor are then applied to determine the extent and intensity of the postoperative therapy. We describe an unusual case with a trilobed tumor and debate the appropriate postoperative management.

SLIT2 promoter methylation analysis in neuroblastoma, Wilms' tumour and renal cell carcinoma

The 3p21.3 RASSF1A tumour suppressor gene (TSG) provides a paradigm for TSGs inactivated by promoter methylation rather than somatic mutations. Recently, we identified frequent promoter methylation without somatic mutations of SLIT2 in lung and breast cancers, suggesting similarities between SLIT2 and RASSF1A TSGs. Epigenetic inactivation of RASSF1A was first described in lung and breast cancers and subsequently in a wide range of human cancers including neuroblastoma, Wilms' tumour and renal cell carcinoma (RCC). These findings prompted us to investigate SLIT2 methylation in these three human cancers. We analysed 49 neuroblastomas (NBs), 37 Wilms' tumours and 48 RCC, and detected SLIT2 promoter methylation in 29% of NB, 38% of Wilms' tumours and 25% of RCC. Previously, we had demonstrated frequent RASSF1A methylation in the same tumour series and frequent CASP8 methylation in the NB and Wilms' tumour samples. However, there was no significant association between SLIT2 promoter methylation and RASSF1A or CASP8 methylation in NB and RCC. In Wilms' tumour, there was a trend for a negative association between RASSF1A and SLIT2 methylation, although this did not reach statistical significance. No associations were detected between SLIT2 promoter methylation and specific clinicopathological features in the tumours analysed. These findings implicate SLIT2 promoter methylation in the pathogenesis of both paediatric and adult cancers and suggest that further investigations of SLIT2 in other tumour types should be pursued. However, epigenetic inactivation of SLIT2 is less frequent than RASSF1A in the tumour types analysed.

Renal function following liver transplantation for unresectable hepatoblastoma

Combination of cyclosporine (CsA) and tacrolimus immunosuppression post-liver transplantation (LT) and the chemotherapeutic drugs used to treat hepatoblastoma (HB), are nephrotoxic. We aimed to determine the severity and duration of nephrotoxicity in children following LT for unresectable HB. We reviewed all children undergoing LT for unresectable HB at the Liver Unit, Birmingham Children's Hospital, UK, from 1991 to July 2000. Thirty-six children undergoing LT for biliary atresia, matched for age and sex, were selected as controls to compare pre- and post-LT renal function. Renal function was determined by estimation of glomerular filtration rate (eGFR) derived from plasma creatinine using Schwartz's formula. Twelve children with HB (mean age of diagnosis 33 months) who underwent LT (mean age 47 months) and 36 controls (mean age of LT 34 months) were studied. CsA was the main immunosuppressive drug used in each group. The median eGFR before, and at 3, 6, 12, 24 and 36 months after LT in HB group was significantly lower than controls (93 vs. 152, 66 vs. 79, 62 vs. 86, 66 vs. 87, 64 vs. 94, 53 vs. 90 mL/min/1.73 m2, respectively; 0.01 < p < 0.03). The reductions in the median eGFR of both the HB group and controls before and at 36 months after LT were 49 and 41%, respectively. At 36 months after LT, there was a trend for partial recovery of the eGFR in the controls but not in the HB group. Children who underwent LT for unresectable HB had renal dysfunction before transplantation that persisted for 36 months after LT.

Strategy for hepatoblastoma management: Transplant versus nontransplant surgery

BACKGROUND

Liver transplantation now is proposed for managing selected hepatoblastoma cases. Indications are not yet well defined.

METHODS

The case records of 34 children with hepatoblastoma treated over a period of 10 years (1991 to 2000) were reviewed retrospectively.

RESULTS

All patients benefited from preoperative chemotherapy. Twenty patients underwent major hepatic resections. Twelve patients, in absence of residual metastasis, underwent liver transplant because the tumour remained unresectable after chemotherapy. Two patients who presented with recurrence after a right hepatectomy, benefited from transplant as a second option. Two other patients did not undergo surgery because of widespread disease or resistance to chemotherapy. Disease-free survival rates were 95% after surgical resection, 100% when primary transplant was performed in patients with good response to chemotherapy, 60% after transplantation in patients with poor response to chemotherapy, 50% in patients with transplant as second option, and 0% in patients not undergoing surgery.

CONCLUSIONS

Transplantation is a potentially curative option for unresectable hepatoblastoma when chemosensitive (decrease in alpha-fetoprotein and decrease in tumour size). In this context, also favourable cases with good response but difficult resections with doubtful margins of resection may best be proposed for primary transplantation. Patients with recurrent or resistant disease are not good candidates.