Laetitia Padovani

Dysembryoplastic Neuroepithelial Tumors Share with Pleomorphic Xanthoastrocytomas and Gangliogliomas BRAFV600E Mutation and Expression

Pediatric cortical glioneuronal benign tumors mainly include gangliogliomas (GG) [differential diagnoses pilocytic astrocytomas (PA) and pleomorphic xanthoastrocytomas (PXA)] and dysembryoplastic neuroepithelial tumor (DNT). DNT include the specific form and the controversial non‐specific form that lack the specific glioneuronal element. Our aims were to search for BRAFV600E mutation and CD34 expression in DNT, PXA, GG and PA to correlate BRAFV600E mutation with BRAFV600E expression and to evaluate their diagnostic and prognostic values. Ninety‐six children were included. BRAFV600E mutation was studied by sequencing and immunohistochemistry; CD34 expression was analyzed by immunohistochemistry. BRAFV600E mutation was detected in PXA (60%), GG (38.7%), DNT (30%, including 3/11 specific and 3/9 non‐specific forms) and PA (12.5%). BRAFV600E expression was recorded in PXA (60%), GG (45.2%) and DNT (30%). CD34 expression was recorded in PXA (60%), GG (58.1%), DNT (25%) and PA (12.5%). Neither CD34 expression nor BRAFV600E status was predictive of prognosis, except for PA tumors where CD34 expression was associated with a shorter overall survival. In conclusion, DNT shared with PXA and GG, BRAFV600E mutation and/or CD34 expression, which represent molecular markers for these tumors, and we recommend searching for CD34 expression and BRAFV600E mutation in all DNT, especially the non‐specific forms.

Neurocognitive function after radiotherapy for paediatric brain tumours

The brain is highly vulnerable to neurotoxic agents during the prime learning period of a childs life. Paediatric patients with brain tumours who are treated with cranial radiation therapy (CRT) often go on to develop neurocognitive deficits, which are reflected in poor academic achievement and impaired memory, attention and processing speed. The extent of these delayed effects varies with radiation dose, brain volume irradiated, and age at treatment, and might also be influenced by genetic factors and individual susceptibility. CRT-induced impairment involves axonal damage and disruption of white matter growth, and can affect brain structures implicated in memory function and neurogenesis, such as the hippocampus. In this article, we review the underlying mechanisms and clinical consequences of CRT-induced neurocognitive damage in survivors of paediatric brain tumours. We discuss the recent application of neuroimaging technologies to identify white matter injury following CRT, and highlight new radiation techniques, pharmacological and neurological interventions, as well as rehabilitation programmes that have potential to minimize neurocognitive impairment following CRT.

Early severe toxicities after capecitabine intake: possible implication of a cytidine deaminase extensive metabolizer profile

We report here the case of a 19-year-old female patient who suffered from extremely severe toxicities (G4 mucitis, fever, diarrhea, alteration of general state) while undergoing low-dose capecitabine treatment for her metastatic corticosurrenaloma. The severe toxicities stopped as soon as treatment was suspended. Interestingly, this patient was not deficient in DPD, a pharmacogenetic syndrome usually associated with increased risk of developing severe/lethal toxicities in patients undergoing fluoropyrimidine therapy, and she had been treated previously with 5-FU with a good tolerance. We then hypothesized that cytidine deaminase (CDA) extensive phenotype could be responsible for the severe toxicities observed with capecitabine. CDA is affected by genetic polymorphism, with subsequent acquisition of either deficient or extensive metabolizer profile. Phenotypic investigations confirmed that CDA activity in this patient was +180% higher than the ones usually recorded in the general population. This strongly suggests that the extensive activation of triple-prodrug capecitabine could have occurred in this patient, resulting in overexposure to 5-FU and its cytotoxic metabolites eventually. This case report suggest for the first time that severe toxicities with a capecitabine-containing protocol could be, at least in part, linked with an extensive-CDA syndrome. The case reported here suggests therefore that besides DPD, screening for CDA activity could be of interest to ensure a better safety in the handling of oral capecitabine at the bedside.

Response of endothelial cells to a dual tyrosine kinase receptor inhibition combined with irradiation

Recent studies suggest the possibility of a direct antiangiogenic effect of anti–epidermal growth factor receptor (EGFR) drugs due to the presence of EGFR on endothelial cells. The aim of this study was to analyze the direct effect on endothelial cells of associating EGFR targeting, vascular endothelial growth factor receptor (VEGFR)-2 targeting, and irradiation. We examined both the cytotoxic effects and the effect on molecular markers resulting from the combined action of gefitinib (Iressa; anti-EGFR), ZM317450 [VEGFR tyrosine kinase inhibitor (VTKI); anti-VEGFR-2], and irradiation (radiation therapy) on HMME7 cells, an immortalized microvascular endothelial cell of human origin. The presence of a functional EGFR pathway sensitive to gefitinib was shown in HMME7 cells (gefitinib-induced decrease in phospho-EGFR, phospho-p42/p44, and phospho-Akt). The stimulation of VEGFR-2 pathway led to an increase in Akt phosphorylation that was inhibited by VTKI. Of note, a post–radiation therapy induction of phospho-p42/p44 was observed on HMME7 cells, and this effect was inhibited by a pretreatment with gefitinib. Based on combination indexes (Chou and Talalay analyses), the associations gefitinib-radiation therapy, VTKI-radiation therapy, VTKI-gefitinib, and gefitinib-VTKI-radiation therapy were found to be additive, slightly synergistic, and markedly synergistic, respectively, for the cytotoxicity on HMME7 cells. Among molecular explanatory factors that were examined, the combination gefitinib-radiation therapy totally abolishes DNA-dependent protein kinase expression, and gefitinib attenuates the radiation therapy–induced enhancement of ERCC1 and augments the VTKI-induced CD95 enhancement. The existence of a radiation therapy–dependent neoangiogenesis may be related to the induction of EGFR pathway in endothelial cells, a phenomenon that can be attenuated by anti-EGFR drugs like gefitinib. In complement to the direct antitumor effects of radiation therapy and anti-EGFR drugs, a strong antiangiogenic effect may be obtained with therapeutic strategies combining radiation therapy with EGFR and VEGFR-2 targeting agents. [Mol Cancer Ther 2005;4(12):1962–71]

Outcome analysis of childhood pilocytic astrocytomas: a retrospective study of 148 cases at a single institution.

Pilocytic astrocytomas (PAs) are characterized by an excellent prognosis although several factors of adverse outcome have been reported. The mitogen‐activated protein kinase pathway plays a major role in their tumorigenesis.

Metronomic etoposide/cyclophosphamide/celecoxib regimen given to children and adolescents with refractory cancer: a preliminary monocentric study.

BACKGROUND Metronomic chemotherapy (MC) is the administration of chemotherapy at doses below the maximal tolerated dose on a frequent schedule of administration, with no prolonged drug-free breaks. OBJECTIVE The aim of this research was to assess the effectiveness and tolerance of a metronomic etoposide/ cyclophosphamide/celecoxib regimen in children and adolescents with refractory cancer. METHODS This retrospective, single-center study evaluated the use of MC with etoposide 25 mg/m(2).d(-1) (days 1-14), cyclophosphamide 25 mg/m(2) d(-1) (days 15-28), and celecoxib 100 to 400 mg/d (days 1-28), in children with refractory, or high-risk relapsing, cancer. Adverse events were determined through laboratory analyses and investigator observations. RESULTS From January 2005 to December 2007, 17 children and adolescents were treated. The best responses observed were stabilizations of the disease that lasted over 20 weeks in 7 patients (41%). Most importantly, in 4 patients (24%) antalgic treatment could be transiently diminished or stopped, and in 1 patient (6%) oxygen support could be stopped for several weeks. Four grade IV platelet toxicities were noted in 3 patients; 2 grade IV anemia occurred in 2 patients (who had platelet and red blood cell transfusions before initiation of treatment); and 1 patient had grade III neutropenia. No other grade III or IV toxicities were noted. Grade II alopecia and stomatitis were observed in 1 patient and grade II vomiting was observed in 2 patients. One patient with meningeal carcinomatosis developed bilateral subdural hematoma for which the role of MC could not be ruled out. Circulating endothelial cells were elevated in 3 out of 3 patients in whom they were quantified and who were progressing while under MC. CONCLUSION The MC regimen we report here was associated with disease stabilization without major toxicities. This assessment of MC in children and adolescents warrants further studies.

Ex vivo cultures of glioblastoma in three-dimensional hydrogel maintain the original tumor growth behavior and are suitable for preclinical drug and radiation sensitivity screening.

Identification of new drugs and predicting drug response are major challenges in oncology, especially for brain tumors, because total surgical resection is difficult and radiation therapy or chemotherapy is often ineffective. With the aim of developing a culture system close to in vivo conditions for testing new drugs, we characterized an ex vivo three-dimensional culture system based on a hyaluronic acid-rich hydrogel and compared it with classical two-dimensional culture conditions. U87-MG glioblastoma cells and seven primary cell cultures of human glioblastomas were subjected to radiation therapy and chemotherapy drugs. It appears that 3D hydrogel preserves the original cancer growth behavior and enables assessment of the sensitivity of malignant gliomas to radiation and drugs with regard to inter-tumoral heterogeneity of therapeutic response. It could be used for preclinical assessment of new therapies.

Three-dimensional conformal radiotherapy for paranasal sinus carcinoma: Clinical results for 25 patients

PURPOSE To assess local control, survival, and clinical and dosimetric prognostic factors in 25 patients with locally advanced maxillary or ethmoid sinus carcinoma treated by three-dimensional conformal radiotherapy (RT). MATERIALS AND METHODS Surgery was performed in 22 patients and was macroscopically complete in 16. Seven patients received chemotherapy (concomitant with RT in four). The following quality indexes were defined for the 95% and 90% isodoses: tumor conformity index, normal tissue conformity index, and global conformity index. RESULTS The median radiation dose to the planned treatment volume was 63 Gy, with a minimal dose of 60 Gy, except in 2 patients whose cancer progressed during RT. The maximal doses tolerated by the structures involved in vision were respected, except for tumors that involved the optic nerve. After a median follow-up of 25 months, 14 local tumor recurrences developed. The major prognostic factors were central nervous system involvement by disease and the presence of nonresectable tumors. The radiation dose and tumor conformity index value were not significant prognostic indicators. Two patients died of acute infectious toxicity, and two developed late ipsilateral ocular toxicity. CONCLUSIONS Improving local control remains the main challenge in RT for paranasal tumors.

Evidence for BRAF V600E and H3F3A K27M double mutations in paediatric glial and glioneuronal tumours

In this short report, we describe three interesting cases of paediatric glial and glioneuronal tumours harbouring both BRAF V600E and H3F3A K27M mutations. Low grade gliomas and glioneuronal tumours (LGG and LGGNT) are the most common paediatric central nervous system (CNS) neoplasms. They include in particular World Health Organization (WHO) grade I pilocytic astrocytomas (PAs), grade II pleomorphic xanthoastrocytomas (PXAs) and gangliogliomas (GGs). Despite their slow growth, incomplete, surgically resected tumours can relapse and cause considerable morbidity and premature death. Recent molecular studies reported that PXA and GG display BRAF V600E mutation [1–3], whereas PA are mainly characterized by KIAA1549:BRAF fusion genes [4–6]; both alterations constitutively activate the BRAF/MEK signalling pathway. In contrast, mutations in H3F3A gene (especially the H3F3A K27M mutation) encoding for histone H3.3, commonly occur in diffuse paediatric high-grade gliomas (HGGs), including diffuse intrinsic pontine gliomas and glioblastomas that preferentially arise at midline locations and carry a dismal prognosis [7–10]. According to recent data, H3F3A K27M mutation reprograms epigenetic landscape and gene expression, which may drive tumourigenesis [11]. Two recent studies, conducted by the same consortium involved in the Paediatric Cancer Genome Project, reported cases with BRAF V600E and H3F3A K27M double mutation; one was reported in a study focused on whole-genome sequencing of paediatric LGG [12] and the other was described by analysing the genomic landscape of paediatric HGG [13]. These results indicate some overlap between the genetic alterations of paediatric LGG and HGG. Here, BRAF and H3F3A mutations were assessed in a small set of LGG and LGGNT diagnosed as PXA, GG and unclassified glial/glioneuronal tumours, and we report three new cases with BRAF V600E and H3F3A K27M double mutation. Clinical characteristics and follow-up of these patients are detailed. Patients’ main clinical and molecular data are summarized in Table 1. Tumours of 25 patients (age at diagnosis less than 20 years) were centrally reviewed by the French Groupe d’Etude en Neuropathologie Oncologique Pédiatrique (GENOP) network and were included in this retrospective study. They encompassed PXAs (five cases), GGs (eight cases) and 12 cases reported as unclassified glial/ glioneuronal tumours for which precise diagnosis remained difficult. Nevertheless, the GENOP discussed various possible diagnoses for these cases; they are reported in Table 1. All patients underwent surgery between 2002 and 2011. For all patients, the following clinical data were collected: age at diagnosis, sex, tumour location and follow-up (date of relapse, date of last medical examination and clinical status at last medical examination). Tumour specimens were obtained according to a protocol approved by the local institutional review board and ethics committee and conducted according to the national regulations. All patients included in this study have provided their written consent. In all cases, surgical specimens were fixed in formalin and embedded in paraffin. Areas of viable and representative tumour were selected and marked by a pathologist (DFB). Then tumour DNA was extracted, and DNA sequences were analysed as previously described [3]. Because of their rarity, pathological diagnosis of paediatric tumours of the CNS may be highly challenging. Therefore, a group of referent paediatric neuropathologists was formed in France (GENOP) with the aim of harmonizing neuropathological diagnosis of these tumours. For our 12 cases in which diagnosis was difficult, the GENOP central review allowed the distinction between diffuse and circumscribed glioma and between benign and malignant tumours, and a better recognition *Both authors equally contributed to this work.

Mathematical modeling of cancer immunotherapy and its synergy with radiotherapy

Combining radiotherapy with immune checkpoint blockade may offer considerable therapeutic impact if the immunosuppressive nature of the tumor microenvironment (TME) can be relieved. In this study, we used mathematical models, which can illustrate the potential synergism between immune checkpoint inhibitors and radiotherapy. A discrete-time pharmacodynamic model of the combination of radiotherapy with inhibitors of the PD1-PDL1 axis and/or the CTLA4 pathway is described. This mathematical framework describes how a growing tumor first elicits and then inhibits an antitumor immune response. This antitumor immune response is described by a primary and a secondary (or memory) response. The primary immune response appears first and is inhibited by the PD1-PDL1 axis, whereas the secondary immune response happens next and is inhibited by the CTLA4 pathway. The effects of irradiation are described by a modified version of the linear-quadratic model. This modeling offers an explanation for the reported biphasic relationship between the size of a tumor and its immunogenicity, as measured by the abscopal effect (an off-target immune response). Furthermore, it explains why discontinuing immunotherapy may result in either tumor recurrence or a durably sustained response. Finally, it describes how synchronizing immunotherapy and radiotherapy can produce synergies. The ability of the model to forecast pharmacodynamic endpoints was validated retrospectively by checking that it could describe data from experimental studies, which investigated the combination of radiotherapy with immune checkpoint inhibitors. In summary, a model such as this could be further used as a simulation tool to facilitate decision making about optimal scheduling of immunotherapy with radiotherapy and perhaps other types of anticancer therapies. Cancer Res; 76(17); 4931-40. ©2016 AACR.