Response assessment in diffuse intrinsic pontine glioma: recommendations from the Response Assessment in Pediatric Neuro-Oncology (RAPNO) working group

Optimising the conduct of clinical trials for diffuse intrinsic pontine glioma involves use of consistent, objective disease assessments and standardised response criteria. The Response Assessment in Pediatric Neuro-Oncology working group, consisting of an international panel of paediatric and adult neuro-oncologists, clinicians, radiologists, radiation oncologists, and neurosurgeons, was established to address issues and unique challenges in assessing response in children with CNS tumours. A working group was formed specifically to address response assessment in children and young adults with diffuse intrinsic pontine glioma and to develop a consensus on recommendations for response assessment. Response should be assessed using MRI of brain and spine, neurological examination, and anti-inflammatory or antiangiogenic drugs. Clinical imaging standards are defined. As with previous consensus recommendations, these recommendations will need to be validated in prospective clinical trials.

Combined Targeting of Mutant p53 and Jumonji Family Histone Demethylase Augments Therapeutic Efficacy of Radiation in H3K27M DIPG

Diffuse intrinsic pontine glioma (DIPG) is an aggressive pediatric brainstem tumor with a 5-year survival of <1%. Up to 80% of the DIPG tumors contain a specific K27M mutation in one of the two genes encoding histone H3 (H3K27M). Furthermore, p53 mutations found in >70–80% of H3K27M DIPG, and mutant p53 status is associated with a decreased response to radiation treatment and worse overall prognosis. Recent evidence indicates that H3K27M mutation disrupts tri-methylation at H3K27 leading to aberrant gene expression. Jumonji family histone demethylases collaborates with H3K27 mutation in DIPG by erasing H3K27 trimethylation and thus contributing to derepression of genes involved in tumorigenesis. Since the first line of treatment for pediatric DIPG is fractionated radiation, we investigated the effects of Jumonji demethylase inhibition with GSK-J4, and mutant p53 targeting/oxidative stress induction with APR-246, on radio-sensitization of human H3K27M DIPG cells. Both APR-246 and GSK-J4 displayed growth inhibitory effects as single agents in H3K27M DIPG cells. Furthermore, both of these agents elicited mild radiosensitizing effects in human DIPG cells (sensitizer enhancement ratios (SERs) of 1.12 and 1.35, respectively; p < 0.05). Strikingly, a combination of APR-246 and GSK-J4 displayed a significant enhancement of radiosensitization, with SER of 1.50 (p < 0.05) at sub-micro-molar concentrations of the drugs (0.5 μM). The molecular mechanism of the observed radiosensitization appears to involve DNA damage repair deficiency triggered by APR-246/GSK-J4, leading to the induction of apoptotic cell death. Thus, a therapeutic approach of combined targeting of mutant p53, oxidative stress induction, and Jumonji demethylase inhibition with radiation in DIPG warrants further investigation.

The intersect of neurosurgery with diffuse intrinsic pontine glioma

An invited article highlighting diffuse intrinsic pontine glioma (DIPG) to celebrate the 75th Anniversary of the Journal of Neurosurgery, a journal known to define surgical nuance and enterprise, is paradoxical since DIPG has long been relegated to surgical abandonment. More recently, however, the neurosurgeon is emerging as a critical stakeholder given our role in tissue sampling, collaborative scientific research, and therapeutic drug delivery. The foundation for this revival lies in an expanding reliance on tissue accession for understanding tumor biology, available funding to fuel research, and strides with interventional drug delivery.

Diagnostics and treatment of diffuse intrinsic pontine glioma: where do we stand?

Introduction

Diffuse intrinsic pontine glioma (DIPG) is a rare clinically, neuro-radiologically, and molecularly defined malignancy of the brainstem with a median overall survival of approximately 11 months. Our aim is to evaluate the current tendency for its treatment in Europe in order to develop (inter)national consensus guidelines.

Methods

Healthcare professionals specialized in DIPG were asked to fill in an online survey with questions regarding usual treatment strategies at diagnosis and at disease progression in their countries and/or their centers, respectively.

Results

Seventy-four healthcare professionals responded to the survey, of which 87.8% were pediatric oncologists. Only 13.5% of the respondents biopsy all of their patients, 41.9% biopsy their patients infrequently. More than half of the respondents (54.1%) treated their patients with radiotherapy only at diagnosis, whereas 44.6% preferred radiotherapy combined with chemotherapy. When the disease progresses, treatment strategies became even more diverse, and the tendency for no treatment increased from 1.4% at diagnosis to 77.0% after second progression. 36.5% of the healthcare professionals treat children younger than 3 years differently than older children at diagnosis. This percentage decreased, when the disease progresses. Most of the participants (51.4%) included less than 25% of their patients in clinical trials.

Conclusion

This survey demonstrates a large heterogeneity of treatment regimens, especially at disease progression. We emphasize the need for international consensus guidelines for the treatment of DIPG, possible by more collaborative clinical trials.

Electronic supplementary material

The online version of this article (10.1007/s11060-019-03287-9) contains supplementary material, which is available to authorized users.

Treatment options for paediatric brainstem gliomas

Paediatric brainstem gliomas (BSGs) can be classified broadly into two distinct categories: focal brainstem gliomas (FBSGs) and diffuse intrinsic pontine gliomas (DIPG). The former account for 20% of paediatric BSGs and are mostly indolent lesions with good prognosis. DIPGs constitute the remaining 80%, and are highly aggressive, malignant tumours having a dismal prognosis; being the foremost cause of death in children with brain tumours. Their poor response to treatment regimens is further complicated by their localization in eloquent brainstem areas, thereby making it difficult to establish a standardized framework of therapeutic intervention. In this review, the authors catalogue and appraise current treatment modalities utilized in the management of paediatric BSGs including steroid use, chemotherapy, radiotherapy, and surgery.

Diverse immunotherapies can effectively treat syngeneic brainstem tumors in the absence of overt toxicity

BACKGROUND

Immunotherapy has shown remarkable clinical promise in the treatment of various types of cancers. However, clinical benefits derive from a highly inflammatory mechanism of action. This presents unique challenges for use in pediatric brainstem tumors including diffuse intrinsic pontine glioma (DIPG), since treatment-related inflammation could cause catastrophic toxicity. Therefore, the goal of this study was to investigate whether inflammatory, immune-based therapies are likely to be too dangerous to pursue for the treatment of pediatric brainstem tumors.

METHODS

To complement previous immunotherapy studies using patient-derived xenografts in immunodeficient mice, we developed fully immunocompetent models of immunotherapy using transplantable, syngeneic tumors. These four models - HSVtk/GCV suicide gene immunotherapy, oncolytic viroimmunotherapy, adoptive T cell transfer, and CAR T cell therapy - have been optimized to treat tumors outside of the CNS and induce a broad spectrum of inflammatory profiles, maximizing the chances of observing brainstem toxicity.

RESULTS

All four models achieved anti-tumor efficacy in the absence of toxicity, with the exception of recombinant vaccinia virus expressing GMCSF, which demonstrated inflammatory toxicity. Histology, imaging, and flow cytometry confirmed the presence of brainstem inflammation in all models. Where used, the addition of immune checkpoint blockade did not introduce toxicity.

CONCLUSIONS

It remains imperative to regard the brainstem with caution for immunotherapeutic intervention. Nonetheless, we show that further careful development of immunotherapies for pediatric brainstem tumors is warranted to harness the potential potency of anti-tumor immune responses, despite their possible toxicity within this anatomically sensitive location.

Brainstem Glioma: Clinical Profile and Challenges of Management in a Developing Country

BACKGROUND AND OBJECTIVES

Brainstem gliomas are relatively rare tumours of the central nervous system which have varying presentations and clinical course. This study aims to analyse the clinical profile and challenges of management of these tumours in a resource-limited country.

METHIODS

We retrospectively analysed the data from the records of the patients managed for briainstem glioma between January 2010 and July 2017.

RESULTS

There were 11 patients in the study (7 males and 4 females). The median age at diagnosis was 9 years. Eight of the patients were less than 15 years. The duration of symptoms ranged from 1 month to 2 years. All the patients had cranial nerve deficits at presentation, while 7 patients had cerebellar signs. Hydrocephalus was present in 4 patients. The lesion was pontine in 9 patients and tectal in 2. Three of the patients with hydrocephalus had ventriculoperitoneal shunt insertion while one patient refused surgery. Only one of the patients had radiotherapy. None of the patients received chemotherapy. A patient was dishcarged against medical advice. One patient is still alive after 4 years while another patient is alive after 2 years. The other 9 patients are dead with a mean survival period of 6 months.

CONCCLUSION

Most of the tumours in this series were located in the pons and ran aggressive courses. Majority of our patients did not have access to radiotherapy while none had chemotherapy.

Nimotuzumab and radiotherapy for treatment of newly diagnosed diffuse intrinsic pontine glioma (DIPG): a phase III clinical study

BACKGROUND

Diffuse intrinsic pontine glioma (DIPG) is a devastating cancer of childhood and adolescence.

METHODS

The study included patients between 3 and 20 years with clinically and radiologically confirmed DIPG. Primary endpoint was 6-month progression-free survival (PFS) following administration of nimotuzumab in combination with external beam radiotherapy (RT). Nimotuzumab was administered intravenously at 150 mg/m² weekly for 12 weeks. Radiotherapy at total dose of 54 Gy was delivered between week 3 and week 9. Response was evaluated based on clinical features and MRI findings according to RECIST criteria at week 12. Thereafter, patients continued to receive nimotuzumab every alternate week until disease progression/unmanageable toxicity. Adverse events (AE) were evaluated according to Common Terminology Criteria for Adverse Events (CTC-AE) Version 3.0 (CTC-AE3).

RESULTS

All 42 patients received at least one dose of nimotuzumab in outpatient settings. Two patients had partial response (4.8%), 27 had stable disease (64.3%), 10 had progressive disease (23.8%) and 3 patients (7.1%) could not be evaluated. The objective response rate (ORR) was 4.8%. Median PFS was 5.8 months and median overall survival (OS) was 9.4 months. Most common drug-related AEs were alopecia (14.3%), vomiting, headache and radiation skin injury (7.1% each). Therapy-related serious adverse events (SAEs) were intra-tumoral bleeding and acute respiratory failure, which were difficult to distinguish from effects of tumor progression.

CONCLUSIONS

Concomitant treatment with RT and nimotuzumab was feasible in an outpatient setting. The PFS and OS were comparable to results achieved with RT and intensive chemotherapy in hospitalized setting.

International experience in the development of patient-derived xenograft models of diffuse intrinsic pontine glioma

PURPOSE

Diffuse intrinsic pontine glioma is the most aggressive form of high grade glioma in children with no effective therapies. There have been no improvements in survival in part due poor understanding of underlying biology, and lack of representative in vitro and in vivo models. Recently, it has been found feasible to use both biopsy and autopsy tumors to generate cultures and xenograft models.

METHODS

To further model development, we evaluated the collective international experience from 8 collaborating centers to develop DIPG pre-clinical models from patient-derived autopsies and biopsies. Univariate and multivariate analysis was performed to determine key factors associated with the success of in vitro and in vivo PDX development.

RESULTS

In vitro cultures were successfully established from 57% of samples (84.2% of biopsies and 38.2% of autopsies). Samples transferred in DMEM media were more likely to establish successful culture than those transported in Hibernate A. In vitro cultures were more successful from biopsies (84.2%) compared with autopsies (38.2%) and as monolayer on laminin-coated plates than as neurospheres. Primary cultures successfully established from autopsy samples were more likely to engraft in animal models than cultures established from biopsies (86.7% vs. 47.4%). Collectively, tumor engraftment was more successful when DIPG samples were directly implanted in mice (68%), rather than after culturing (40.7%).

CONCLUSION

This multi-center study provides valuable information on the success rate of establishing patient-derived pre-clinical models of DIPG. The results can lead to further optimization of DIPG model development and ultimately assist in the investigation of new therapies for this aggressive pediatric brain tumor.

Somatostatin receptor subtype 1 might be a predictor of better response to therapy in medullary thyroid carcinoma

PURPOSE

Medullary thyroid carcinoma (MTC) is a malignant neoplasm of parafollicular cells. Because it is a neuroendocrine tumor, it has known somatostatin receptors (SSTRs). The actual frequencies of the SSTR subtypes and their potential influences (by binding with endogenous somatostatin) on MTC cell proliferation have not been fully elucidated to date. The present study evaluated the occurrence of SSTR subtypes 1, 2, 3 and 5 as well as the possible role that each subtype plays in the clinical evolution of patients with MTC.

METHODS

This retrospective, longitudinal study analyzed thyroid surgical material from 42 patients with MTC. Immunohistochemical staining was performed with monoclonal antibodies against subtypes 1, 2, 3 and 5 of SSTR. The histological material was classified as negative, focal positive or diffuse positive, in relation to each of the SSTR subtypes. The initial response to treatment, clinical course and patient mortality rate were assessed and related to the presence of SSTR subtypes.

RESULTS

The most prevalent SSTR subtype was SSTR 3, which was found in 81% of the patients, when considering any pattern of positivity. However, subtype 2 had the lowest number of positive patients, with 28.6% demonstrating any positive pattern. Subtypes 1 and 5 had an intermediate prevalence of positivity, with subtype 1 present in 45.2% of the patients and subtype 5 positive in 54.8% of the patients, when considering any pattern of positivity. The presence of STR 1, in the form of diffuse positivity, independently predicted a better response to the initial therapy, with a hazard ratio (HR) of 4.80 (p = 0.03).

CONCLUSION

This is the first study to show the correlation of the presence of SSTR1, detected by monoclonal immunohistochemical techniques, and better response to initial treatment and possibly better long-term clinical response in patients with MTC. In addition, these patients had low positivity rates for SSTR2, which might explain the low sensitivity of diagnostic and limited therapeutic response to octrotide based radioisotopes.

The dual mTOR kinase inhibitor TAK228 inhibits tumorigenicity and enhances radiosensitization in diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG) is an invasive and treatment-refractory pediatric brain tumor. Primary DIPG tumors harbor a number of mutations including alterations in PTEN, AKT, and PI3K and exhibit activation of mammalian Target of Rapamycin Complex 1 and 2 (mTORC1/2). mTORC1/2 regulate protein translation, cell growth, survival, invasion, and metabolism. Pharmacological inhibition of mTORC1 is minimally effective in DIPG. However, the activity of dual TORC kinase inhibitors has not been examined in this tumor type. Nanomolar levels of the mTORC1/2 inhibitor TAK228 reduced expression of p-AKT^S473 and p-S6^S240/244 and suppressed the growth of DIPG lines JHH-DIPG1, SF7761, and SU-DIPG-XIII. TAK228 induced apoptosis in DIPG cells and cooperated with radiation to further block proliferation and enhance apoptosis. TAK228 monotherapy inhibited the tumorigenicity of a murine orthotopic model of DIPG, more than doubling median survival (p = 0.0017) versus vehicle. We conclude that dual mTOR inhibition is a promising potential candidate for DIPG treatment.

The international diffuse intrinsic pontine glioma registry: an infrastructure to accelerate collaborative research for an orphan disease

Diffuse intrinsic pontine glioma (DIPG), a rare, often fatal childhood brain tumor, remains a major therapeutic challenge. In 2012, investigators, funded by the DIPG Collaborative (a philanthropic partnership among 29 private foundations), launched the International DIPG Registry (IDIPGR) to advance understanding of DIPG. Comprised of comprehensive deidentified but linked clinical, imaging, histopathological, and genomic repositories, the IDIPGR uses standardized case report forms for uniform data collection; serial imaging and histopathology are centrally reviewed by IDIPGR neuro-radiologists and neuro-pathologists, respectively. Tissue and genomic data, and cell cultures derived from autopsies coordinated by the IDIPGR are available to investigators for studies approved by the Scientific Advisory Committee. From April 2012 to December 2016, 670 patients diagnosed with DIPG have been enrolled from 55 participating institutions in the US, Canada, Australia and New Zealand. The radiology repository contains 3558 studies from 448 patients. The pathology repository contains tissue on 81 patients with another 98 samples available for submission. Fresh DIPG tissue from seven autopsies has been sent to investigators to develop primary cell cultures. The bioinformatics repository contains next-generation sequencing data on 66 tumors. Nine projects using data/tissue from the IDIPGR by 13 principle investigators from around the world are now underway. The IDIPGR, a successful alliance among philanthropic agencies and investigators, has developed and maintained a highly collaborative, hypothesis-driven research infrastructure for interdisciplinary and translational projects in DIPG to improve diagnosis, response assessment, treatment and outcome for patients.

Re-Examining the Need for Tissue Diagnosis in Pediatric Diffuse Intrinsic Pontine Gliomas: A Review

Diffuse intrinsic pontine glioma (DIPG) is a malignant brain tumor of childhood that carries an extremely poor prognosis. There are ~200-300 new cases diagnosed each year, [1, 2] and little progress has been made in changing the prognosis and outcome of the tumor since it was first documented in the literature in 1926 [3]. The median overall survival is 8-11 months [4], with an overall survival rate of 30% at 1 year, and less than 10% at 2 years [4]. This review will provide background information on DIPGs, a historical look at the trends in caring for DIPG, and current trends in diagnosis and treatment. By changing the way we care for these terminal tumors, we can work towards having a better understanding of the underlying molecular biology, and attempt to develop better chemotherapeutic tools to combat the disease.

Pleomorphic Xanthoastrocytoma with Anaplastic Features in the Tectal Region in a Young Adult Patient: A Case Report

BACKGROUND

Pleomorphic xanthoastrocytomas (PXAs) in the tectal region are exceedingly rare and have distinctive clinicopathological features.

CASE PRESENTATION

A 17-year-old man was admitted to our hospital owing to headache and diplopia. Magnetic resonance imaging showed a mass lesion in the tectal gland accompanied by obstructive hydrocephalus. A biopsy and third ventriculostomy were performed. Pathological examination revealed a PXA. Total excision of the lesion was achieved via an occipital transtentorial procedure performed 6 weeks after the biopsy. A pathological examination at that time showed a PXA with anaplastic features and a high mitotic index in surgical specimens. The patient's symptoms improved after the second operation, and radiation and temozolomide-based chemotherapy were administered. No recurrence was found at 24 months after the second operation.

CONCLUSIONS

Maximum resections are recommended in cases with anaplastic features such as a high mitotic index in biopsy specimens because of the likelihood of recurrence and the low overall survival rate. We administered radiotherapy and temozolomide-based chemotherapy because of the high mitotic activity detected in surgical specimens. The postoperative course in this case is currently deemed acceptable.

Preclinical Biosafety Evaluation of Genetically Modified Human Adipose Tissue-Derived Mesenchymal Stem Cells for Clinical Applications to Brainstem Glioma

Stem-cell based gene therapy is a promising novel therapeutic approach for inoperable invasive tumors, including brainstem glioma. Previously, we demonstrated the therapeutic potential of human adipose tissue-derived mesenchymal stem cells (hAT-MSC) genetically engineered to express a secreted form of tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL) against brainstem glioma. However, safety concerns should be comprehensively investigated before clinical applications of hAT-MSC.sTRAIL. At first, we injected stereotactically low (1.2 × 10(5) cells/18 μL), medium (2.4 × 10(5)/18 μL), or high dose (3.6 × 10(5)/18 μL) of hAT-MSC.sTRAIL into the brainstems of immunodeficient mice reflecting the plan of the future clinical trial. Local toxicity, systemic toxicity, secondary tumor formation, and biodistribution of hAT-MSC.sTRAIL were investigated. Next, presence of hAT-MSC.sTRAIL was confirmed in the brain and major organs at 4, 9, and 14 weeks in brainstem glioma-bearing mice. In the 15-week subchronic toxicity test, no serious adverse events in terms of body weight, food consumption, clinical symptom, urinalysis, hematology, clinical chemistry, organ weight, and histopathology were observed. In the 26-week tumorigenicity test, hAT-MSC.sTRAIL made no detectable tumors, whereas positive control U-87 MG cells made huge tumors in the brainstem. No remaining hAT-MSC.sTRAIL was observed in any organs examined, including the brainstem at 15 or 26 weeks. In brainstem glioma-bearing mice, injected hAT-MSC.sTRAIL was observed, but gradually decreased over time in the brain. The mRNA of human specific GAPDH and TRAIL was not detected in all major organs. These results indicate that the hAT-MSC.sTRAIL could be applicable to the future clinical trials in terms of biosafety.

Pathological crying and emotional vasovagal syncope as symptoms of a dorsally exophytic medullary tumor

A 3-year-old boy with a dorsally exophytic tumor arising from the rostral medulla presented with a chief complaint of a change in his emotional behavior, most notably anxiety and paroxysmal crying often followed by syncope. Magnetic resonance imaging revealed that the tumor pushed on the dorsal surface of the medulla and displaced the medulla anteriorly, and also displaced the cerebellar vermis upward and slightly posteriorly. Tissue from a partial resection was diagnosed as a pilocytic astrocytoma. The symptoms did not improved after surgery, but did improve clinically after chemotherapy with vincristine and carboplatin, at which time MR showed a reduction in tumor size. We diagnosed the paroxysmal crying as 'pathological crying' and the syncope with increased anxiety as 'emotional vasovagal syncope'. This case stresses the importance of recognition of this rare presentation as an indication of a medullary tumor.

[Our Experience of Providing Home End-of-Life Care for a Child with a Brain Tumor - Overview of Issues Including Environmental Adjustment and Family Care]

INTRODUCTION

We provided home end-of-life care to a child with a brain tumor. As cases of children with malignancies who receive such care have rarely been described in Japan, we report our experience with this patient.

CASE REPORT

An 11-year-old previously healthy boy was found to have a brainstem glioma in December X. The tumor was reduced by radiotherapy and chemotherapy, but relapse was noted in August X plus 1. Best supportive care alone was selected for this patient. Before the initiation of home care, we consulted a designated hospital for pediatric cancer treatment in the area and requested a case- worker from the child/home section in his resident area. As the patient was too young for long-term care insurance, we immediately applied for a physical disability certificate to augment welfare support. After the initiation of home care, swallowing function diminished markedly, but we provided guidance on dietary contents and suction, allowing continued oral ingestion by prioritizing his and his family's wishes. In January X plus 2 of the following year, his respiratory condition worsened after the development of aspiration pneumonitis, and he died at home.

SUMMARY

We advocate the establishment of a regional network so that children with brain tumors can receive end-of-life care at home.

Diffuse intrinsic pontine gliomas: treatments and controversies

Diffuse intrinsic pontine gliomas (DIPGs) are a fairly common pediatric brain tumor, and children with these tumors have a dismal prognosis. They generally are diagnosed within the first decade of life, and due to their location within the pons, these tumors are not surgically resectable. The median survival for children with DIPGs is less than 1 year, in spite of decades of clinical trial development of unique approaches to radiation therapy and chemotherapy. Novel therapies are under investigation for these deadly tumors. As clinicians and researchers make a concerted effort to obtain tumor tissue, the molecular signals of these tumors are being investigated in an attempt to uncover targetable therapies for DIPGs. In addition, direct application of chemotherapies into the tumor (convection-enhanced delivery) is being investigated as a novel delivery system for treatment of DIPGs. Overall, DIPGs require creative thinking and a disciplined approach for development of a therapy that can improve the prognosis for these unfortunate children.

[Diffusely growing brainstem tumors in children and adolescents: has alternating treatment policy changed results?]

The authors analyze the MEDLINE publications in the past 20 years on the treatment of diffusely growing brainstem tumors in children and adolescents. Radiation and chemoradiation are main treatments for these diseases. The use of different radiation dose fractionation modes and different combinations of cytotoxic drugs has caused no significant changes in long-term results. Whatever the used treatment option is, most patients die within the next 1-2 years after tumor progression. Prognosis mainly depends on the biological properties of a tumor and patients with low-grade glioma generally survive longer. The late effects of radiotherapy make quality of life worse in long-term survivors after treatment. Hopes to enhance therapeutic effectiveness are placed on the development of targeted therapy options based on molecular biological markers.

Clinical management and outcome of histologically verified adult brainstem gliomas in Switzerland: a retrospective analysis of 21 patients

Because of low incidence, mixed study populations and paucity of clinical and histological data, the management of adult brainstem gliomas (BSGs) remains non-standardized. We here describe characteristics, treatment and outcome of patients with exclusively histologically confirmed adult BSGs. A retrospective chart review of adults (age >18 years) was conducted. BSG was defined as a glial tumor located in the midbrain, pons or medulla. Characteristics, management and outcome were analyzed. Twenty one patients (17 males; median age 41 years) were diagnosed between 2004 and 2012 by biopsy (n = 15), partial (n = 4) or complete resection (n = 2). Diagnoses were glioblastoma (WHO grade IV, n = 6), anaplastic astrocytoma (WHO grade III, n = 7), diffuse astrocytoma (WHO grade II, n = 6) and pilocytic astrocytoma (WHO grade I, n = 2). Diffuse gliomas were mainly located in the pons and frequently showed MRI contrast enhancement. Endophytic growth was common (16 vs. 5). Postoperative therapy in low-grade (WHO grade I/II) and high-grade gliomas (WHO grade III/IV) consisted of radiotherapy alone (three in each group), radiochemotherapy (2 vs. 6), chemotherapy alone (0 vs. 2) or no postoperative therapy (3 vs. 1). Median PFS (24.1 vs. 5.8 months; log-rank, p = 0.009) and mOS (30.5 vs. 11.5 months; log-rank, p = 0.028) was significantly better in WHO grade II than in WHO grade III/IV tumors. Second-line therapy considerably varied. Histologically verification of adult BSGs is feasible and has an impact on postoperative treatment. Low-grade gliomas can simple be followed or treated with radiotherapy alone. Radiochemotherapy with temozolomide can safely be prescribed for high-grade gliomas without additional CNS toxicities.

Diffuse intrinsic pontine glioma treated with prolonged temozolomide and radiotherapy--results of a United Kingdom phase II trial (CNS 2007 04)

Diffuse intrinsic pontine glioma (DIPG) has a dismal prognosis with no chemotherapy regimen so far resulting in any significant improvement over standard radiotherapy. In this trial, a prolonged regimen (21/28d) of temozolomide was studied with the aim of overcoming O(6)-methylguanine methyltransferase (MGMT) mediated resistance. Forty-three patients with a defined clinico-radiological diagnosis of DIPG received radiotherapy and concomitant temozolomide (75 mg/m(2)) after which up to 12 courses of 21d of adjuvant temozolomide (75-100mg/m(2)) were given 4 weekly. The trial used a 2-stage design and passed interim analysis. At diagnosis median age was 8 years (2-20 years), 81% had cranial nerve abnormalities, 76% ataxia and 57% long tract signs. Median Karnofsky/Lansky score was 80 (10-100). Patients received a median of three courses of adjuvant temozolomide, five received all 12 courses and seven did not start adjuvant treatment. Three patients were withdrawn from study treatment due to haematological toxicity and 10 had a dose reduction. No other significant toxicity related to temozolomide was noted. Overall survival (OS) (95% confidence interval (CI)) was 56% (40%, 69%) at 9 months, 35% (21%, 49%) at 1 year and 17% (7%, 30%) at 2 years. Median survival was 9.5 months (range 7.5-11.4 months). There were five 2-year survivors with a median age of 13.6 years at diagnosis. This trial demonstrated no survival benefit of the addition of dose dense temozolomide, to standard radiotherapy in children with classical DIPG. However, a subgroup of adolescent DIPG patients did have a prolonged survival, which needs further exploration.

PD-0332991, a CDK4/6 inhibitor, significantly prolongs survival in a genetically engineered mouse model of brainstem glioma

Diffuse intrinsic pontine glioma (DIPG) is an incurable tumor that arises in the brainstem of children. To date there is not a single approved drug to effectively treat these tumors and thus novel therapies are desperately needed. Recent studies suggest that a significant fraction of these tumors contain alterations in cell cycle regulatory genes including amplification of the D-type cyclins and CDK4/6, and less commonly, loss of Ink4a-ARF leading to aberrant cell proliferation. In this study, we evaluated the therapeutic approach of targeting the cyclin-CDK-Retinoblastoma (Rb) pathway in a genetically engineered PDGF-B-driven brainstem glioma (BSG) mouse model. We found that PD-0332991 (PD), a CDK4/6 inhibitor, induces cell-cycle arrest in our PDGF-B; Ink4a-ARF deficient model both in vitro and in vivo. By contrast, the PDGF-B; p53 deficient model was mostly resistant to treatment with PD. We noted that a 7-day treatment course with PD significantly prolonged survival by 12% in the PDGF-B; Ink4a-ARF deficient BSG model. Furthermore, a single dose of 10 Gy radiation therapy (RT) followed by 7 days of treatment with PD increased the survival by 19% in comparison to RT alone. These findings provide the rationale for evaluating PD in children with Ink4a-ARF deficient gliomas.

Morphologic characteristics and immunohistochemical profile of diffuse intrinsic pontine gliomas

Tumors of the central nervous system are the second most common malignancy in children. In particular, diffuse intrinsic pontine gliomas (DIPGs) are aggressive tumors with poor prognosis and account for 10% to 25% of pediatric brain tumors. The majority of DIPGs are astrocytic, infiltrative, and localized to the pons. Studies have shown median survival times of less than a year, with 90% of children dying within 2 years. We built multitissue arrays with 24 postmortem DIPG samples and analyzed the morphology and expression of several proteins (p53, EGFR, GFAP, MIB1, BMI1, β-catenin, p16, Nanog, Nestin, OCT4, OLIG2, SOX2) with the goal of identifying potential treatment targets and improving our understanding of the biology of these tumors. The majority of DIPGs were high-grade gliomas (22), with 18 cases having features of glioblastoma (World Health Organization [WHO] grade IV) and 4 cases with high-grade features consistent with anaplastic astrocytoma (WHO grade III). One case was low grade (WHO grade II), and 1 case showed intermediate features between a grade II and grade III glioma (low mitotic rate but increased cellularity and cell atypia), being difficult to grade precisely. The majority of the tumors were positive for GFAP (24/24), MIB1 (23/24), OLIG2 (22/24), p16 (20/24), p53 (20/24), SOX2 (19/24), EGFR (16/24), and BMI1 (9/24). Our results suggest that dysregulation of EGFR and p53 may play an important role in the development of DIPGs. The majority of DIPGs express stem cell markers such as SOX2 and OLIG2, consistent with a role for tumor stem cells in the origin and maintenance of these tumors. Targeted therapies against these proteins could be beneficial in treatment.