L1 chimeric transcripts are expressed in healthy brain and their deregulation in glioma follows that of their host locus.

Besides the consequences of retrotransposition, long interspersed element 1 (L1) retrotransposons can affect the host genome through their antisense promoter. In addition to the sense promoter, the evolutionarily recent L1 retrotransposons, which are present in several thousand copies, also possess an anti-sense promoter that can produce L1 chimeric transcripts (LCT) composed of the L1 5' UTR followed by the adjacent genomic sequence. The full extent to which LCT expression occurs in a given tissue and whether disruption of the defense mechanisms that normally control L1 retrotransposons affects their expression and function in cancer cells, remain to be established. By using CLIFinder, a dedicated bioinformatics tool, we found that LCT expression was widespread in normal brain and aggressive glioma samples, and that approximately 17% of recent L1 retrotransposons, from the L1PA1 to L1PA7 subfamilies, were involved in their production. Importantly, the transcriptional activities of the L1 antisense promoters and of their host loci were coupled. Accordingly, we detected LCT-producing L1 retrotransposons mainly in transcriptionally active genes and genomic loci. Moreover, changes in the host genomic locus expression level in glioma were associated with a similar change in LCT expression level, regardless of the L1 promoter methylation status. Our findings support a model in which the host genomic locus transcriptional activity is the main driving force of LCT expression. We hypothesize that this model is more applicable when host gene and LCT are transcribed from the same strand.

Transcriptional alterations in glioma result primarily from DNA methylation-independent mechanisms.

In cancer cells, aberrant DNA methylation is commonly associated with transcriptional alterations, including silencing of tumor suppressor genes. However, multiple epigenetic mechanisms, including polycomb repressive marks, contribute to gene deregulation in cancer. To dissect the relative contribution of DNA methylation-dependent and -independent mechanisms to transcriptional alterations at CpG island/promoter-associated genes in cancer, we studied 70 samples of adult glioma, a widespread type of brain tumor, classified according to their isocitrate dehydrogenase (IDH1) mutation status. We found that most transcriptional alterations in tumor samples were DNA methylation-independent. Instead, altered histone H3 trimethylation at lysine 27 (H3K27me3) was the predominant molecular defect at deregulated genes. Our results also suggest that the presence of a bivalent chromatin signature at CpG island promoters in stem cells predisposes not only to hypermethylation, as widely documented, but more generally to all types of transcriptional alterations in transformed cells. In addition, the gene expression strength in healthy brain cells influences the choice between DNA methylation- and H3K27me3-associated silencing in glioma. Highly expressed genes were more likely to be repressed by H3K27me3 than by DNA methylation. Our findings support a model in which altered H3K27me3 dynamics, more specifically defects in the interplay between polycomb protein complexes and the brain-specific transcriptional machinery, is the main cause of transcriptional alteration in glioma cells. Our study provides the first comprehensive description of epigenetic changes in glioma and their relative contribution to transcriptional changes. It may be useful for the design of drugs targeting cancer-related epigenetic defects.

Tyro3 Targeting as a Radiosensitizing Strategy in Bladder Cancer through Cell Cycle Dysregulation.

Bladder cancer is a common cancer; it is the tenth most common cancer in the world. Around one fourth of all diagnosed patients have muscle-invasive bladder cancer (MIBC), characterized by advanced tumors and which remains a lethal disease. The standard treatment for MIBC is the bladder removal by surgery. However, bladder-preserving alternatives are emerging by combining chemotherapy, radiotherapy and minimal surgery, aiming to increase the patient's quality of life. The aim of the study was to improve these treatments by investigating a novel approach where in addition to radiotherapy, a receptor, TYRO3, a member of TAM receptor tyrosine kinase family known to be highly expressed on the bladder cancer cells and involved in the control of cell survival is targeted. For this, we evaluated the influence of TYRO3 expression levels on a colony or cell survival assays, DNA damage, γH2AX foci formation, gene expression profiling and cell cycle regulation, after radiation on different bladder cell models. We found that TYRO3 expression impacts the radiation response via the cell cycle dysregulation with noeffets on the DNA repair. Therefore, targeting TYRO3 is a promising sensitization marker that could be clinically employed in future treatments.

The Long Non-Coding RNA HOXA-AS2 Promotes Proliferation of Glioma Stem Cells and Modulates Their Inflammation Pathway Mainly through Post-Transcriptional Regulation.

Glioblastomas represent approximatively half of all gliomas and are the most deadly and aggressive form. Their therapeutic resistance and tumor relapse rely on a subpopulation of cells that are called Glioma Stem Cells (GSCs). Here, we investigated the role of the long non-coding RNA HOXA-AS2 in GSC biology using descriptive and functional analyses of glioma samples classified according to their isocitrate dehydrogenase (IDH) gene mutation status, and of GSC lines. We found that HOXA-AS2 is overexpressed only in aggressive (IDHwt) glioma and GSC lines. ShRNA-based depletion of HOXA-AS2 in GSCs decreased cell proliferation and altered the expression of several hundreds of genes. Integrative analysis revealed that these expression changes were not associated with changes in DNA methylation or chromatin signatures at the promoter of the majority of genes deregulated following HOXA-AS2 silencing in GSCs, suggesting a post-transcriptional regulation. In addition, transcription factor binding motif enrichment and correlation analyses indicated that HOXA-AS2 affects, directly or indirectly, the expression of key transcription factors implicated in GCS biology, including E2F8, E2F1, STAT1, and ATF3, thus contributing to GCS aggressiveness by promoting their proliferation and modulating the inflammation pathway.

Preoperative stereotactic radiosurgery for brain metastases: the STEP study protocol for a multicentre, prospective, phase-II trial.

BACKGROUND: Surgery is an important therapeutic option for brain metastases. Currently, postoperative stereotactic radiosurgery (SRT) leads to 6-month and 1-year local control estimated at 70 and 62% respectively. However, there is an increased risk of radio-necrosis and leptomeningeal relapse. Preoperative SRT might be an alternative, providing local control remains at least equivalent. It is an innovative concept that could enable the stereotactic benefits to be retained with advantages over post-operative SRT. METHODS: STEP has been designed as a national, multicentre, open-label, prospective, non-randomized, phase-II trial. Seventeen patients are expected to be recruited in the study from 7 sites and they will be followed for 12 months. Patients with more than 4 distinct brain metastases, including one with a surgical indication, and an indication for SRT and surgery, are eligible for enrolment. The primary objective of the trial is to assess 6-month local control after preoperative SRT. The secondary objectives include the assessment of local control, radio-necrosis, overall survival, toxicities, leptomeningeal relapse, distant control, cognitive function, and quality of life. The experimental design is based on a Flemming plan. DISCUSSION: There is very little data available in the literature on preoperative SRT: there have only been 3 American single or two-centre retrospective studies. STEP is the first prospective trial on preoperative SRT in Europe. Compared to postoperative stereotactic radiotherapy, preoperative stereotactic radiotherapy will enable reduction in the irradiated volume, leptomeningeal relapse and the total duration of the combined treatment (from 4 to 6 weeks to a few days). TRIAL REGISTRATION NUMBER: Clinicaltrials.gov: NCT04503772 , registered on August 07, 2020. Identifier with the French National Agency for the Safety of Medicines and Health Products (ANSM): N°ID RCB 2020-A00403-36, registered in February 2020. PROTOCOL: version 4, 07 December 2020.

A 13-gene expression-based radioresistance score highlights the heterogeneity in the response to radiation therapy across HPV-negative HNSCC molecular subtypes.

BACKGROUND: Radiotherapy for head and neck squamous cell carcinomas (HNSCC) is associated with a substantial morbidity and inconsistent efficacy. Human papillomavirus (HPV)-positive status is recognized as a marker of increased radiosensitivity. Our goal was to identify molecular markers associated with benefit to radiotherapy in patients with HPV-negative disease. METHODS: Gene expression profiles from public repositories were downloaded for data mining. Training sets included 421 HPV-negative HNSCC tumors from The Cancer Genome Atlas (TCGA) and 32 HNSCC cell lines with available radiosensitivity data (GSE79368). A radioresistance (RadR) score was computed using the single sample Gene Set Enrichment Analysis tool. The validation sets included two panels of cell lines (NCI-60 and GSE21644) and HPV-negative HNSCC tumor datasets, including 44 (GSE6631), 82 (GSE39366), and 179 (GSE65858) patients, respectively. We finally performed an integrated analysis of the RadR score with known recurrent genomic alterations in HNSCC, patterns of protein expression, biological hallmarks, and patterns of drug sensitivity using TCGA and the E-MTAB-3610 dataset (659 pancancer cell lines, 140 drugs). RESULTS: We identified 13 genes differentially expressed between tumor and normal head and neck mucosa that were associated with radioresistance in vitro and in patients. The 13-gene expression-based RadR score was associated with recurrence in patients treated with surgery and adjuvant radiotherapy but not with surgery alone. It was significantly different among different molecular subtypes of HPV-negative HNSCC and was significantly lower in the "atypical" molecular subtype. An integrated analysis of RadR score with genomic alterations, protein expression, biological hallmarks and patterns of drug sensitivity showed a significant association with CCND1 amplification, fibronectin expression, seven hallmarks (including epithelial-to-mesenchymal transition and unfolded protein response), and increased sensitivity to elesclomol, an HSP90 inhibitor. CONCLUSIONS: Our study highlights the clinical relevance of the molecular classification of HNSCC and the RadR score to refine radiation strategies in HPV-negative disease.

Detection of the alternative lengthening of telomeres pathway in malignant gliomas for improved molecular diagnosis.

Human malignant gliomas exhibit acquisition of either one of two telomere maintenance mechanisms, resulting from either reactivation of telomerase expression or activation of an alternative lengthening of telomeres (ALT) mechanism. In the present study, we analyzed 63 human malignant gliomas for the presence of ALT-specific extrachromosomal circles of telomeric DNA (C-circles) and measured telomerase expression, telomeric DNA content (Telo/Alu method), and telomeric repeat-containing RNAs (TERRA) levels. We also assessed histomolecular markers routinely used in clinical practice. The presence of C-circles significantly correlated with IDH1/2 mutation, MGMT exon 1 methylation, low Ki-67 immunostaining, increased telomeric DNA content, absence of functional ATRX protein and level of HTERT gene expression. In multivariate analysis, we observed a trend to a correlation between elevated TERRA levels and increased survival. Interestingly, the C-circles assay allowed to detect ALT activation in glioblastomas exhibiting wild-type IDH1/2 and ATRX expression. These results suggest that, after the correlations uncovered here have been confirmed on larger numbers of tumors, telomeric markers might be useful in improving diagnosis. They also point out to the utility of using the specific, sensitive and quantitative C-circle and Telo/Alu assays that can work with as few as 30 ng of tumor DNA.

The tumoral A genotype of the MGMT rs34180180 single-nucleotide polymorphism in aggressive gliomas is associated with shorter patients' survival.

Malignant gliomas are the most common primary brain tumors. Grade III and IV gliomas harboring wild-type IDH1/2 are the most aggressive. In addition to surgery and radiotherapy, concomitant and adjuvant chemotherapy with temozolomide (TMZ) significantly improves overall survival (OS). The methylation status of the O(6)-methylguanine-DNA methyltransferase (MGMT) promoter is predictive of TMZ response and a prognostic marker of cancer outcome. However, the promoter regions the methylation of which correlates best with survival in aggressive glioma and whether the promoter methylation status predictive value could be refined or improved by other MGMT-associated molecular markers are not precisely known. In a cohort of 87 malignant gliomas treated with radiotherapy and TMZ-based chemotherapy, we retrospectively determined the MGMT promoter methylation status, genotyped single nucleotide polymorphisms (SNPs) in the promoter region and quantified MGMT mRNA expression level. Each of these variables was correlated with each other and with the patients' OS. We found that methylation of the CpG sites within MGMT exon 1 best correlated with OS and MGMT expression levels, and confirmed MGMT methylation as a stronger independent prognostic factor compared to MGMT transcription levels. Our main finding is that the presence of only the A allele at the rs34180180 SNP in the tumor was significantly associated with shorter OS, independently of the MGMT methylation status. In conclusion, in the clinic, rs34180180 SNP genotyping could improve the prognostic value of the MGMT promoter methylation assay in patients with aggressive glioma treated with TMZ.

Role of Akt in human malignant glioma: from oncogenesis to tumor aggressiveness.

Gathering evidence has revealed that Akt signaling pathway plays an important role in glioma progression and aggressiveness. Among Akt kinases the most studied, Akt1, has been involved in many cellular processes that are in favor of cell malignancy. More recently, the actions of the two other isoforms, Akt2 and Akt3 have emerged in glioma. After a description of Akt pathway activation, we will explore the role of each isoform in malignant glioma that strengthens the current preclinical and clinical studies evaluating the impact of Akt pathway targeting in glioblastomas.

New in-capillary electrophoretic kinase assays to evaluate inhibitors of the PI3k/Akt/mTOR signaling pathway.

Human kinases are one of the most promising targets for cancer therapy. Methods able to measure the effects of drugs on these cell agents remain crucial for biologists and medicinal chemists. The current work therefore sought to develop an in-capillary enzymatic assay based on capillary electrophoresis (CE) to evaluate the inhibition of phosphatidylinositol-3-kinase (PI3K), protein kinase B (Akt), and the mammalian target of rapamycin (mTOR). These kinases belong to the same signaling pathway PI3K/Akt/mTOR. For this proposal, the capillary was used as a nanoreactor in which a few nanoliters of the kinase, its substrate, adenosine triphosphate (ATP), and the potent inhibitor were separately injected. A transverse diffusion of laminar flow profiles (TDLFP) approach was employed to mix the reactants. Adenosine diphosphate (ADP ) was detected online at 254 nm. The CE assay was first developed on the α isoform of PI3K. It was compared to five commercial kits frequently used to assess kinase inhibition, based on time-resolved fluorescence resonance energy transfer (TR-FRET) and bioluminescence. Each assay was evaluated in terms of sensitivity (S/B), reproducibility (Z'), and variability (r (2)). This CE method was easily extended to assay the inhibition of the ß, γ, and δ isoforms of PI3K, and of the other kinases of the pathway, Akt1 and mTOR, since it is based on in-capillary mixing by TDLFP and on ADP quantification by simple UV absorption. This work shows for the first time the evaluation of inhibitors of the kinases of the PI3K/Akt/mTOR pathway using a common in-capillary CE assay. Several inhibitors with a wide range of affinity toward these enzymes were tested.

Integrated High-Throughput Screening and Large-Scale Isobolographic Analysis to Accelerate the Discovery of Radiosensitizers With Greater Selectivity for Cancer Cells.

PURPOSE: High-throughput screening (HTS) platforms have been widely used to identify candidate anticancer drugs and drug-drug combinations; however, HTS-based identification of new drug-ionizing radiation (IR) combinations has rarely been reported. Herein, we developed an integrated approach including cell-based HTS and computational large-scale isobolographic analysis to accelerate the identification of radiosensitizing compounds acting strongly and more specifically on cancer cells. METHODS AND MATERIALS: In a 384-well plate format, 160 compounds likely to interfere with the cell response to radiation were screened on human glioblastoma (U251-MG) and cervix carcinoma (ME-180) cell lines, as well as on normal fibroblasts (CCD-19Lu). After drug exposure, cells were irradiated or not and short-term cell survival was assessed by high-throughput cell microscopy. Computational large-scale dose-response and isobolographic approach were used to identify promising synergistic drugs radiosensitizing cancer cells rather than normal cells. Synergy of a promising compound was confirmed on ME-180 cells by an independent 96-well assay protocol, and finally, by the gold-standard colony forming assay. RESULTS: We retained 4 compounds synergistic at 2 isoeffects in U251-MG and ME-180 cell lines and 11 compounds synergistically effective in only one cancer cell line. Among these 15 promising radiosensitizers, 5 compounds showed limited toxicity combined or not with IR on normal fibroblasts. CONCLUSIONS: Overall, this study demonstrated that HTS chemoradiation screening together with large-scale computational analysis is an efficient tool to identify synergistic drug-IR combinations, with concomitant assessment of unwanted toxicity on normal fibroblasts. It sparks expectations to accelerate the discovery of highly desired agents improving the therapeutic index of radiation therapy.

Temporal regulation of transgene expression controlled by amino acid availability in human T cells.

T cell therapy strategies, from allogeneic stem cell transplantation toward genetically-modified T cells infusion, develop powerful anti-tumor effects but are often accompanied by side effects and their efficacy remains sometimes to be improved. It therefore appears important to provide a flexible and easily reversible gene expression regulation system to control T cells activity. We developed a gene expression regulation technology that exploits the physiological GCN2-ATF4 pathway's ability to induce gene expression in T cells in response to one essential amino acid deficiency. We first demonstrated the functionality of NUTRIREG in human T cells by transient expression of reporter genes. We then validated that NUTRIREG can be used in human T cells to transiently express a therapeutic gene such as IL-10. Overall, our results represent a solid basis for the promising use of NUTRIREG to regulate transgene expression in human T cells in a reversible way, and more generally for numerous preventive or curative therapeutic possibilities in cellular immunotherapy strategies.

Differential Remodeling of the Oxylipin Pool After FLASH Versus Conventional Dose-Rate Irradiation In Vitro and In Vivo.

PURPOSE: The products of lipid peroxidation have been implicated in human diseases and aging. This prompted us to investigate the response to conventional (CONV) versus FLASH irradiation of oxylipins, a family of bioactive lipid metabolites derived from omega-3 or omega-6 polyunsaturated fatty acids through oxygen-dependent non-enzymatic as well as dioxygenase-mediated free radical reactions. METHODS AND MATERIALS: Ultrahigh performance liquid chromatography coupled to tandem mass spectrometry was used to quantify the expression of 37 oxylipins derived from eicosatetraenoic, eicosapentaenoic and docosahexaenoic acid in mouse lung and in normal or cancer cells exposed to either radiation modality under precise monitoring of the temperature and oxygenation. Among the 37 isomers assayed, 14-16 were present in high enough amount to enable quantitative analysis. The endpoints were the expression of oxylipins as a function of the dose of radiation, normoxia versus hypoxia, temperature and post-irradiation time. RESULTS: In normal, normoxic cells at 37°C radiation elicited destruction and neosynthesis of oxylipins acting antagonistically on a background subject to rapid remodeling by oxygenases. Neosynthesis was observed in the CONV mode only, in such a way that the level of oxylipins at 5 minutes after FLASH irradiation was 20-50% lower than in non-irradiated and CONV-irradiated cells. Hypoxia mitigated the differential CONV versus FLASH response in some oxylipins. These patterns were not reproduced in tumor cells. Depression of specific oxylipins following FLASH irradiation was observed in mouse lung at 5 min following irradiation, with near complete recovery in 24 hours and further remodeling at one week and two months post-irradiation. CONCLUSIONS: Down-regulation of oxylipins was a hallmark of FLASH irradiation specific of normal cells. Temperature effects suggest that this process occurs via diffusion-controlled, bimolecular recombination of a primary radical species upstream from peroxyl radical formation and evoke a major role of the membrane composition and fluidity in response to the FLASH modality.

Proton FLASH Radiation Therapy and Immune Infiltration: Evaluation in an Orthotopic Glioma Rat Model.

PURPOSE: FLASH radiation therapy (FLASH-RT) is a promising radiation technique that uses ultrahigh doses of radiation to increase the therapeutic window of the treatment. FLASH-RT has been observed to provide normal tissue sparing at high dose rates and similar tumor control compared with conventional RT, yet the biological processes governing these radiobiological effects are still unknown. In this study, we sought to investigate the potential immune response generated by FLASH-RT in a high dose of proton therapy in an orthotopic glioma rat model. METHODS AND MATERIALS: We cranially irradiated rats with a single high dose (25 Gy) using FLASH dose rate proton irradiation (257 ± 2 Gy/s) or conventional dose rate proton irradiation (4 ± 0.02 Gy/s). We first assessed the protective FLASH effect that resulted in our setup through behavioral studies in naïve rats. This was followed by a comprehensive analysis of immune cells in blood, healthy tissue of the brain, and tumor microenvironment by flow cytometry. RESULTS: Proton FLASH-RT spared memory impairment produced by conventional high-dose proton therapy and induced a similar tumor infiltrating lymphocyte recruitment. Additionally, a general neuroinflammation that was similar in both dose rates was observed. CONCLUSIONS: Overall, this study demonstrated that FLASH proton therapy offers a neuro-protective effect even at high doses while mounting an effective lymphoid immune response in the tumor.

Oxygen supplementation in anesthesia can block FLASH effect and anti-tumor immunity in conventional proton therapy.

BACKGROUND: Radiation-induced neurocognitive dysfunction is a major adverse effect of brain radiation therapy and has specific relevance in pediatric oncology, where serious cognitive deficits have been reported in survivors of pediatric brain tumors. Moreover, many pediatric patients receive proton therapy under general anesthesia or sedation to guarantee precise ballistics with a high oxygen content for safety. The present study addresses the relevant question of the potential effect of supplemental oxygen administered during anesthesia on normal tissue toxicity and investigates the anti-tumor immune response generated following conventional and FLASH proton therapy. METHODS: Rats (Fischer 344) were cranially irradiated with a single high dose of proton therapy (15 Gy or 25 Gy) using FLASH dose rate proton irradiation (257 ± 2 Gy/s) or conventional dose rate proton irradiation (4 ± 0.02 Gy/s), and the toxicities in the normal tissue were examined by histological, cytometric and behavioral analysis. Glioblastoma-bearing rats were irradiated in the same manner and tumor-infiltrating leukocytes were quantified by flow cytometry. RESULTS: Our findings indicate that supplemental oxygen has an adverse impact on both functional and anatomical evaluations of normal brain following conventional and FLASH proton therapy. In addition, oxygen supplementation in anesthesia is particularly detrimental for anti-tumor immune response by preventing a strong immune cell infiltration into tumoral tissues following conventional proton therapy. CONCLUSIONS: These results demonstrate the need to further optimize anesthesia protocols used in radiotherapy with the goal of preserving normal tissues and achieving tumor control, specifically in combination with immunotherapy agents.

Proton therapy is a type of precise radiotherapy that can have reduced side effects. Children undergoing proton therapy are often given a general anesthetic, supplemented with high oxygen levels as a measure of safety. However, the consequences of modifying the oxygen concentration in the treatment have not been studied. In this study, we evaluated the consequences of adding oxygen in the anesthesia in a model of brain tumor after conventional proton therapy and a new radiotherapy technique, FLASH proton therapy. We observed that oxygen supplementation can cause more brain damage in FLASH proton therapy and block anti-tumor immune cell infiltration into the tumor in conventional proton therapy. Overall, this study should be taken into consideration when designing new protocols of radiotherapy, specifically those including FLASH proton therapy and combinations with immune-targeted treatments.

Waiting times before initiation of radiotherapy might not affect outcomes for patients with glioblastoma: a French retrospective analysis of patients treated in the era of concomitant temozolomide and radiotherapy.

Purpose of this study was to determine the effect of waiting time for radiotherapy on overall survival of patients with glioblastoma treated in the EORTC-NCIC trial at 18 centers in France. A total of 400 adult patients with glioblastoma who were treated between January 1, 2006 and December 31, 2006 were included. There were 282 patients with "minimum criteria" according to the EORTC-NCIC trial: (i) concurrent chemotherapy with temozolomide; and (ii) age between 18 and 70 years old. Among these patients, 229 were treated with adjuvant temozolomide and were classified as "maximal criteria". One-hundred and eighteen patients were in the "without minimal criteria" group. Waiting time from the first symptom (FS-RT), pathology diagnosis (P-RT), multidisciplinary meeting (MM-RT), surgery (S-RT), and CT scan for delineation (CT-RT) until the start of radiotherapy were recorded. Median follow-up for all patients was 327 days. Overall, median FS-RT, P-RT, MM-RT, CT-RT, and S-RT times were 77, 36, 32, 12, and 41 days, respectively. Median, and 12 and 24-month overall survival were 409 days, and 56.3 ± 2.1 % and 27.6 ± 2.6 %, respectively. Univariate analysis failed to reveal a difference in survival, irrespective of the delay. In multivariate analysis, independent favorable prognostic factors for overall survival were age (p ≤ 0.0001) and type of surgery (p = 0.0006). In this large series treated during the EORTC-NCIC protocol period, waiting time until radiotherapy did not seem to affect patient outcome.

DTI Abnormalities Related to Glioblastoma: A Prospective Comparative Study with Metastasis and Healthy Subjects.

(1) Background: Glioblastoma multiforme (GBM) shows complex mechanisms of spreading of the tumor cells, up to remote areas, and little is still known of these mechanisms, thus we focused on MRI abnormalities observable in the tumor and the brain adjacent to the lesion, up to the contralateral hemisphere, with a special interest on tensor diffusion imaging informing on white matter architecture; (2) Material and Methods: volumes, macroscopic volume (MV), brain-adjacent-tumor (BAT) volume and abnormal color-coded DTI volume (aCCV), and region-of-interest samples (probe volumes, ipsi, and contra lateral to the lesion), with their MRI characteristics, apparent diffusion coefficient (ADC), fractional anisotropy (FA) values, and number of fibers (DTI fiber tracking) were analyzed in patients suffering GBM (n = 15) and metastasis (n = 9), and healthy subjects (n = 15), using ad hoc statistical methods (type I error = 5%) (3) Results: GBM volumes were larger than metastasis volumes, aCCV being larger in GBM and BAT ADC was higher in metastasis, ADC decreased centripetally in metastasis, FA increased centripetally either in GBM or metastasis, MV and BAT FA values were higher in GBM, ipsi FA values of GBM ROIs were higher than those of metastasis, and the GBM ipsi number of fibers was higher than the GBM contra number of fibers; (4) Conclusions: The MV, BAT and especially the aCCV, as well as their related water diffusion characteristics, could be useful biomarkers in oncology and functional oncology.

Local control and radionecrosis of brain metastases from non-small-cell lung cancer treated by hypofractionated stereotactic radiotherapy: Evaluation of predictive factors.

Background: The objective of our study was to report predictive factors of local control (LC) and radionecrosis (RN) of brain metastases (BM) of non-small cell lung carcinoma (NSCLC) treated by multifractionated stereotactic radiotherapy (MF-SRT) according to French recommendations. Method: From 2012 to 2020, 87 patients with 101 BM were retrospectively included. The median age was 63 years (37-85). GTV was defined using contrast-enhanced T1w MRI and was isotropically extended by 2 mm to form PTV. Mean maximum BM diameter was 24.5 mm (10-46). Patients were treated with dynamic arctherapy from May 2012 to February 2016 and then with VMAT. The total prescribed dose was 23.1 Gy prescribed to the encompassing 70% isodose, in 3 fractions. Results: LC rates at 6 months, 1 year and 2 years was 95.7%, 90.7% and 87.9% respectively. In multivariate analysis, high GTV Dmin (HR = 0.822, p = 0.012) was in favor of better LC whereas a large maximum diameter was predictive of poor LC (HR = 1.124, p = 0.02). GTV Dmin of 27.4 Gy was identified as a discriminant threshold of LC. In case of GTV Dmin ≥ 27.4 Gy, LC at 1 year was 95.3% versus 75.1% with GTV Dmin < 27.4 Gy. Cumulative incidence of RN at 6 months, 1 year and 2 years was 6.3%, 15.4% and 18.1%, respectively. In multivariate analysis, only dyslipidemia was predictive of RN (HR = 2.69, p = 0.03). No dosimetric predictive factor of RN was found in our study. Conclusion: MF-SRT (3x7.7 Gy on 70% isodose line, with PTV = GTV + 2 mm; according to French recommendations) of BM from NSCLC gives high LC rates with acceptable RN rate. A GTV Dmin of at least 27.4 Gy could be proposed to optimize dosimetric objectives. No dosimetric predictive factors of RN were found in this study. However, dyslipidemia was identified as a potential predictive factor of RN.

Clinical and technical challenges of cancer reirradiation: Words of wisdom.

Since the development of new radiotherapy techniques that have improved healthy tissue sparing, reirradiation (reRT) has become possible. The selection of patients eligible for reRT is complex given that it can induce severe or even fatal side effects. The first step should therefore be to assess, in the context of multidisciplinary staff meeting, the patient's physical status, the presence of sequelae resulting from the first irradiation and the best treatment option available. ReRT can be performed either curatively or palliatively to treat a cancer-related symptom that is detrimental to the patient's quality of life. The selected techniques for reRT should provide the best protection of healthy tissue. The construction of target volumes and the evaluation of constraints regarding the doses that can be used in this context have not yet been fully codified. These points raised in the literature suggest that randomized studies should be undertaken to answer pending questions.

Outcome of giant pituitary tumors requiring surgery.

Objective: The management of giant pituitary tumors is complex, with few publications and recommendations. Consequently, patient's care mainly relies on clinical experience. We report here a first large series of patients with giant pituitary tumors managed by a multidisciplinary expert team, focusing on treatments and outcome. Methods: A retrospective cohort study was conducted. Giant pituitary tumors were defined by a main diameter > 40mm. Macroprolactinomas sensitive to dopamine agonists were excluded. All patients were operated by a single neurosurgical team. After surgery, multimodal management was proposed, including hormone replacement, radiotherapy and anti-tumor medical therapies. Outcome was modeled using Kaplan-Meyer representation. A logistic regression model was built to identify the risk factors associated with surgical complications. Results: 63 consecutive patients presented a giant adenoma, most often with visual defects. Patients were operated once, twice or three times in 59%, 40% and 1% of cases respectively, mainly through endoscopic endonasal approach. Giant adenomas included gonadotroph, corticotroph, somatotroph, lactotroph and mixed GH-PRL subtypes in 67%, 14%, 11%, 6% and 2% of patients respectively. Vision improved in 89% of patients with prior visual defects. Severe surgical complications occurred in 11% of patients, mainly for tumors > 50 mm requiring microscopic transcranial approach. Additional radiotherapy was needed for 29% of patients, 3 to 56 months after first surgery. For 6% of patients, Temozolomide treatment was required, 19 to 66 months after first surgery. Conclusions: Giant pituitary tumors require multimodal management, with a central role of surgery. Most often, tumor control can be achieved by expert multidisciplinary teams.