Advancements in Image-Based Models for High-Grade Gliomas Might Be Accelerated.

The first half of 2022 saw the publication of several major research advances in image-based models and artificial intelligence applications to optimize treatment strategies for high-grade gliomas, the deadliest brain tumors. We review them and discuss the barriers that delay their entry into clinical practice; particularly, the small sample size and the heterogeneity of the study designs and methodologies used. We will also write about the poor and late palliation that patients suffering from high-grade glioma can count on at the end of life, as well as the current legislative instruments, with particular reference to Italy. We suggest measures to accelerate the gradual progress in image-based models and end of life care for patients with high-grade glioma.

Radiotherapy of high-grade gliomas: dealing with a stalemate.

This article discusses the studies on radiotherapy of high-grade gliomas published between January 1, 2022, and June 30, 2022, with special reference to their molecular biology basis. The focus was on advances in radioresistance, radiosensitization and the toxicity of radiotherapy treatments. In the first half of 2022, several important advances have been made in understanding resistance mechanisms in high-grade gliomas. Furthermore, the development of several radiosensitization procedures for these deadly tumors, including studies with small molecule radiosensitizers, new fractionation protocols, and new immunostimulatory agents, has progressed in both the preclinical and clinical settings, reflecting the frantic research effort in the field. However, since 2005 our research efforts fail to produce significant improvements to treatment guidelines for high-grade gliomas. Possible reasons for this stalemate and measures to overcome it are discussed.

Recapitulating the Key Advances in the Diagnosis and Prognosis of High-Grade Gliomas: Second Half of 2021 Update.

High-grade gliomas (World Health Organization grades III and IV) are the most frequent and fatal brain tumors, with median overall survivals of 24-72 and 14-16 months, respectively. We reviewed the progress in the diagnosis and prognosis of high-grade gliomas published in the second half of 2021. A literature search was performed in PubMed using the general terms "radio* and gliom*" and a time limit from 1 July 2021 to 31 December 2021. Important advances were provided in both imaging and non-imaging diagnoses of these hard-to-treat cancers. Our prognostic capacity also increased during the second half of 2021. This review article demonstrates slow, but steady improvements, both scientifically and technically, which express an increased chance that patients with high-grade gliomas may be correctly diagnosed without invasive procedures. The prognosis of those patients strictly depends on the final results of that complex diagnostic process, with widely varying survival rates.

Most recent update of preclinical and clinical data on radioresistance and radiosensitivity of high-grade gliomas-a radiation oncologist's perspective.

PURPOSE: This review article discusses the studies concerning advances in radiotherapy of high-grade gliomas published in the second half of 2021. METHODS: A literature search was performed in PubMed using the terms ("gliom* and radio*") and time limits 1 July 2021-31 December 2021. The articles were then manually selected for relevance to the analyzed topics. RESULTS: Considerable progress has been made in the preclinical field on the mechanisms of radioresistance and radiosensitization of high-grade gliomas (HGG). However, fewer early-phase (I/II) clinical trials have been performed and, of the latter, even fewer have produced results that justify moving to phase III. In the 6­month period under consideration, no studies were published that would lead to a change in clinical practice and the overall survival (OS) of patients remained similar to that of 2005, the year in which it increased significantly for the last time thanks to introduction of the alkylating agent temozolomide. CONCLUSION: After 17 years of stalemate in improving the OS of patients with HGG, an in-depth analysis of the causes should be carried out in order to identify whether the research efforts conducted so far, including in the radiotherapeutic field, have been the most effective or require improvement. In our opinion, in addition to the therapeutic difficulties related to the biology of HGG tumors (e.g., high infiltrating capacity, multiple resistance mechanisms, blood-brain barrier), some public research policy choices may also play a role, especially in consideration of the limited interest of the pharmaceutical industry in the field of rare cancers.

Improving control of high-grade glioma by ultra-hyper-fractionated radiotherapy.

Ionizing radiation is a mainstay of high-grade glioma therapy. The current standard radiotherapeutic schedule involves a total 60 Gy split in 2.0 Gy fractions delivered on weekdays for six weeks. Thereafter, almost invariably the tumor relapses and progresses. In vitro studies have demonstrated that the therapeutic effectiveness of ionizing radiation towards high-grade glioma cells is greatly increased by splitting the total dose in fractions ten times smaller [0.1-0.5 Gy instead of standard 2.0 Gy-ultra-hyper-fractionated radiotherapy (ultra-hyper-FRT)]. Recently, it became possible to consistently translate this therapeutic effect to the animal setting, by using glioma-initiating cell-driven faithful animal modeling. A re-analysis of the literature reporting radiotherapeutic clinical trials also suggests that the lower the average fraction size, the higher is the achievable overall survival of patients. However, average fraction sizes ≤ 0.5 Gy have never been thoroughly investigated in the clinics. We propose to study in the clinical setting the therapeutic effect of an ultra-hyper-FRT schedule promptly extending the conventional radiation component of the current guidelines ("Stupp") therapeutic protocol.

Ultra-hyper-fractionated radiotherapy for high-grade gliomas.

High-grade gliomas (HGGs; WHO grades III and IV) are invariably lethal brain tumors. Low-dose hyper-radiosensitivity (HRS) of HGG is a well-established phenomenon in vitro. However, possibly linked to the unavailability of accurate animal models of the diseases, this therapeutic effect could not be consistently translated to the animal setting, thus impairing its subsequent clinical development. The purpose of this study was to develop radiotherapeutic (RT) schedules permitting to significantly improve the overall survival of faithful animal models of HGG that have been recently made available. We used primary glioma initiating cell (GIC)-driven orthotopic animal models that accurately recapitulate the heterogeneity and growth patterns of the patients' tumors, to investigate the therapeutic effects of low radiation doses toward HGG. With the same total dose, RT fractions ≤0.5 Gy twice per week [ultra-hyper-fractionation (ultra-hyper-FRT)] started at early stages of tumor progression (a condition that in the clinical setting often occurs at the end of the guidelines treatment) improved the effectiveness of RT and the animal survival in comparison to standard fractions. For the same cumulative dose, the use of fractions ≤0.5 Gy may permit to escape one or more tumor resistance mechanisms thus increasing the effectiveness of RT and the overall animal survival. These findings suggest investigating in the clinical setting the therapeutic effect of an ultra-hyper-FRT schedule promptly extending the conventional RT component of the current guideline ("Stupp") therapeutic protocol.

Radiotherapy of High-Grade Gliomas: First Half of 2021 Update with Special Reference to Radiosensitization Studies.

Albeit the effort to develop targeted therapies for patients with high-grade gliomas (WHO grades III and IV) is evidenced by hundreds of current clinical trials, radiation remains one of the few effective therapeutic options for them. This review article analyzes the updates on the topic "radiotherapy of high-grade gliomas" during the period 1 January 2021-30 June 2021. The high number of articles retrieved in PubMed using the search terms ("gliom* and radio*") and manually selected for relevance indicates the feverish research currently ongoing on the subject. During the last semester, significant advances were provided in both the preclinical and clinical settings concerning the diagnosis and prognosis of high-grade gliomas, their radioresistance, and the inevitable side effects of their treatment with radiation. The novel information concerning tumor radiosensitization was of special interest in terms of therapeutic perspective and was discussed in detail.

The efficacy and toxicity of ATM inhibition in glioblastoma initiating cells-driven tumor models.

The Ataxia Telangiectasia Mutated (ATM)-mediated DNA damage response (DDR) is a major mechanism of resistance of glioblastoma (GB) - initiating cells (GICs) to radiotherapy. The closely related Ataxia Telangiectasia and Rad3-related protein (ATR) is also involved in tumor resistance to radio- and chemotherapy. It has been shown that pharmacological inhibition of ATM protein may overcome the DDR-mediated resistance in GICs and significantly radiosensitize GIC-driven GB. Albeit not essential for life as shown by the decade-long lifespan of AT patients, the ATM protein may be involved in a number of important functions other than the response to DNA damage. We discuss our current knowledge about the toxicity of pharmacologic inhibition of ATM and ATR proteins.

Radiosensitization of orthotopic GIC-driven glioblastoma by doxycycline causes skin damage.

Doxycycline (DXC) is a tetracycline antibiotic which has been proposed as a breast cancer radiosensitizer by specifically reducing the expression of the DNA repair enzyme DNA PK in breast cancer initiating cells. Since DXC presents favorable pharmacokinetics properties including the capacity to cross the blood-brain barrier, it has been hypothesized that it could radiosensitize brain tumors as well. We have investigated the radiosensitizing capacity of DXC towards human glioma initiating cells (GIC)-driven orthotopic glioblastomas (GB) in NOD/SCID mice that faithfully mimic the growth properties of the clinical tumors of origin. DXC at 10 mg/Kg body weight was subcutaneously delivered daily, 5 days/week for 4 weeks. At the same time, radiotherapeutic fractions of 0.25 Gy to the head were delivered every 3-4 days (twice/week) for 15 weeks. No survival advantage was observed in DXC-treated mice as compared to vehicle-treated mice by this radiosensitizing protocol. On the contrary, skin damage with hair loss and deep ulcers were observed after 4 weeks in DXC-treated mice leading to discontinuation of drug treatment. These results do not support the use of DXC as a radiosensitizer for brain tumors and indicate skin damage as an important side effect of DXC.

Author Correction: Faithful animal modelling of human glioma by using primary initiating cells and its implications for radiosensitization therapy.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Augmentation of 5-Aminolevulinic Acid Treatment of Glioblastoma by Adding Ciprofloxacin, Deferiprone, 5-Fluorouracil and Febuxostat: The CAALA Regimen.

The CAALA (Complex Augmentation of ALA) regimen was developed with the goal of redressing some of the weaknesses of 5-aminolevulinic acid (5-ALA) use in glioblastoma treatment as it now stands. 5-ALA is approved for use prior to glioblastoma surgery to better demarcate tumor from brain tissue. 5-ALA is also used in intraoperative photodynamic treatment of glioblastoma by virtue of uptake of 5-ALA and its preferential conversion to protoporphyrin IX in glioblastoma cells. Protoporphyrin IX becomes cytotoxic after exposure to 410 nm or 635 nm light. CAALA uses four currently-marketed drugs-the antibiotic ciprofloxacin, the iron chelator deferiprone, the antimetabolite 5-FU, and the xanthine oxidase inhibitor febuxostat-that all have evidence of ability to both increase 5-ALA mediated intraoperative glioblastoma demarcation and photodynamic cytotoxicity of in situ glioblastoma cells. Data from testing the full CAALA on living minipigs xenotransplanted with human glioblastoma cells will determine safety and potential for benefit in advancing CAALA to a clinical trial.

Faithful animal modelling of human glioma by using primary initiating cells and its implications for radiosensitization therapy [ARRIVE 1].

It has been reported that the ATM kinase inhibitor KU60019 preferentially radiosensitizes orthotopic high grade gliomas (HGG) driven by established U87 and U1242 cell lines bearing specific TP53 mutations. We wished to determine whether those results could be extended to tumors driven by primary glioma initiating cells (GIC) that closely mimic clinical tumors. Orthotopic HGG were developed in immunodeficient non-obese diabetic-severe combined immunodeficient (NOD-SCID) mice by intracranial injection of primary GIC isolated from the adult glioblastoma COMI (acronym of patient's name) and the pediatric anaplastic astrocytoma 239/12. Similar to the clinical tumors of origin, the orthotopic tumors COMI and 239/12 displayed different growth properties with a voluminous expansive lesion that exerted considerable mass effect on the adjacent structures and an infiltrating, gliomatosis-like growth pattern with limited compressive attitude, respectively. Significant elongations of median animal survival bearing the adult COMI tumor was observed after one KU60019 convection enhanced delivery followed by total 7.5 Gy of ionizing radiation delivered in fifteen 0.5 Gy fractions, as compared to animals treated with vehicle + ionizing radiation (105 vs 89 days; ratio: 0.847; 95% CI of ratio 0.4969 to 1.198; P:0.0417) [ARRIVE 16]. Similarly, a trend to increased median survival was observed with the radiosensitized pediatric tumor 239/12 (186 vs 167 days; ratio: 0.8978; 95% CI of ratio: 0.5352 to 1.260; P: 0.0891) [ARRIVE 16]. Our results indicate that radiosensitization by KU60019 is effective towards different orthotopic gliomas that faithfully mimic the clinical tumors and that multiple GIC-based animal models may be essential to develop novel therapeutic protocols for HGG transferable to the clinics.

Brain microglia activation induced by intracranial administration of oligonucleotides and its pharmacological modulation.

Oligonucleotide overloading results in type I interferonopathies such as the Aicardi-Goutiéres Syndrome, a progressive encephalopathy determined by an immune response against endogenous DNA/RNA molecules. No therapy targeting pathogenic mechanisms is available for affected patients. Accordingly, we set up an in vitro/in vivo experimental model aimed at reproducing the pathogenic mechanisms of type I interferonopathies, in order to develop an effective pharmacological modulation and toxicological alterations caused by intracranial delivery of encapsulated CpG. The in vitro model used Aicardi-Goutiéres Syndrome immortalized lymphocytes activated by interferon I and co-cultured with human astrocytes; lymphocyte neurotoxicity was attenuated by the calcineurin-inhibitor Tacrolimus and by the anti-interferon monoclonal antibody Sifalimumab. The in vivo model was set up in mice by subcutaneous injection of encapsulated CpG oligonucleotides; the immune-stimulating activity was demonstrated by cytometric analysis in the spleen. To mime pathogenesis of type I interferonopathies in the central nervous system, CpG oligonucleotides were administered intracranially in mice. In the brain, CpG overload induced a rapid activation of macrophage-like microglial cells and focal accumulation mononuclear cells. The subcutaneous administration of Tacrolimus and, more potently, Sifalimumab attenuated CpG-induced brain alterations. These findings shed light on molecular mechanisms triggered by oligonucleotides to induce brain damage. Monoclonal antibodies inhibiting interferon seem a promising therapeutic strategy to protect brain in type I interferonopathies.

ATR kinase inhibitors NVP-BEZ235 and AZD6738 effectively penetrate the brain after systemic administration.

Ataxia Telangiectasia and Rad3 related protein (ATR) is a central mediator of the response to DNA damage that may cause the quiescent resistance of cancer initiating cells to genotoxic radiotherapy. NVP-BEZ235 is a dual PI3K/mTOR inhibitor that also effectively targets ATR with IC50 = 21 × 10- 9 M in cells. AZD6738 does not target significantly PI3K/mTOR-related kinases but specifically inhibits ATR with IC50 = 74 × 10- 9 M in cells. Both drugs have been proposed as radiosensitizers of different tumors including glioblastoma (GB), the most malignant brain tumor. In order to study the radiosensitizing properties of ATR inhibitors NVP-BEZ235 and AZD6738 towards GB, we have preliminarily investigated their capacity to penetrate the brain after systemic administration. Tumor-free CD-1 mice were inoculated i.p. with 25 mg/Kg body weight of NVP-BEZ235 or AZD6738. 1, 2, 6 and 8 h later, blood was collected by retro-orbital bleeding after which the mice were euthanized and the brains explanted. Blood and brain samples were then extracted and NVP-BEZ235 and AZD6738 concentrations determined by High Performance Liquid Chromatography/Mass Spectrometry. We found for NVP-BEZ235 and especially for AZD6738, elevated bioavailability and effective brain penetration after intraperitoneal administration. Albeit low drug and radiation dosages were used, a trend to toxicity of NVP-BEZ235 followed by ionizing radiation (IR) towards mice bearing primary glioma initiating cells (GIC)-driven orthotopic tumors was yet observed, as compared to AZD6738 + IR and vehicle+IR. Survival was never improved with median values of 99, 86 and 101 days for vehicle+IR, NVP-BEZ235 + IR and AZD6738 + IR-treated mice, respectively. Although the present results indicate favorable pharmacokinetics properties of ATR inhibitors NVP-BEZ235 and AZD6738, they do not lend support to their use as radiosensitizers of GB.

Blocking epithelial-to-mesenchymal transition in glioblastoma with a sextet of repurposed drugs: the EIS regimen.

This paper outlines a treatment protocol to run alongside of standard current treatment of glioblastoma- resection, temozolomide and radiation. The epithelial to mesenchymal transition (EMT) inhibiting sextet, EIS Regimen, uses the ancillary attributes of six older medicines to impede EMT during glioblastoma. EMT is an actively motile, therapy-resisting, low proliferation, transient state that is an integral feature of cancers' lethality generally and of glioblastoma specifically. It is believed to be during the EMT state that glioblastoma's centrifugal migration occurs. EMT is also a feature of untreated glioblastoma but is enhanced by chemotherapy, by radiation and by surgical trauma. EIS Regimen uses the antifungal drug itraconazole to block Hedgehog signaling, the antidiabetes drug metformin to block AMP kinase (AMPK), the analgesic drug naproxen to block Rac1, the anti-fibrosis drug pirfenidone to block transforming growth factor-beta (TGF-beta), the psychiatric drug quetiapine to block receptor activator NFkB ligand (RANKL) and the antibiotic rifampin to block Wnt- all by their previously established ancillary attributes. All these systems have been identified as triggers of EMT and worthy targets to inhibit. The EIS Regimen drugs have a good safety profile when used individually. They are not expected to have any new side effects when combined. Further studies of the EIS Regimen are needed.

Advances in drug delivery to high grade gliomas.

If cancer is hard to be treated, brain cancer is even more, caused by the inability of many effective drugs given systemically to cross the blood brain and blood tumor barriers and reach adequate concentrations at the tumor sites. Effective delivery of drugs to brain cancer tissues is thus a necessary, albeit not sufficient, condition to effectively target the disease. In order to analyze the current status of research on drug delivery to high grade gliomas (HGG-WHO grades III and IV), the most frequent and aggressive brain cancers, a literature search was conducted in PubMed using the terms: "drug delivery and brain tumor" over the publication year 2015. Currently explored drug delivery techniques for HGG include the convection and permeabilization-enhanced deliveries, drug-releasing depots and Ommaya reservoirs. The efficacy/safety ratio widely varies among these techniques and the success of current efforts to increase this ratio widely varies as well.

Non-routine Tracers for PET Imaging of High-grade Glioma.

Thorough imaging is crucial for diagnosis and treatment of high-grade gliomas (HGG), lethal brain tumours with median survival ranging 1-5 years after diagnosis. Positron-emission tomography (PET) is acquiring importance in imaging of HGG since it has the formidable advantage of providing information on tumour metabolism that may be critical for correct diagnosis and treatment planning. Recently employed PET tracers designed for the non-routine investigation of specific aspects of HGG metabolism, including hypoxia, neoangiogenesis, expression of integrins and stem cell markers, are reviewed herein. A thorough choice from among these non-routine tracers may provide important metabolic information complementing those obtained with more common PET analyses, for the sake of diagnostic, prognostic, treatment planning or research purposes.

Positron emission tomography of high-grade gliomas.

High-grade gliomas [HGG (WHO grades III-IV)] are almost invariably fatal. Imaging of HGG is important for orientating diagnosis, prognosis and treatment planning and is crucial for development of novel, more effective therapies. Given the potentially unlimited number of usable tracing molecules and the elevated number of available radionuclides, PET allows gathering multiple informations on HGG including data on tissue metabolism and drug pharmacokinetics. PET studies on the diagnosis, prognosis and treatment of HGG carried out by most frequently used tracers and radionuclides ((11)C and (18)F) and published in 2014 have been reviewed. These studies demonstrate that a thorough choice of tracers may confer elevated diagnostic and prognostic power to PET imaging of HGG. They also suggest that a combination of PET and MRI may give the most complete and reliable imaging information on HGG and that research on hybrid PET/MRI may be paying back in terms of improved diagnosis, prognosis and treatment planning of these deadly tumours.

Nanoparticle-mediated drug delivery to high-grade gliomas.

High grade gliomas (HGGs) are fatal brain tumors due to their infiltration capacity and the presence of resistant cell populations. Further, the brain is naturally protected from many exogenous molecules by the brain blood barrier (BBB), which limits or cancels passage of cytotoxic drugs to the tumor sites. In order to cope with the latter problem, nanoparticle (NP)-based carriers are intensively investigated, due to multiple possibilities to drive them across the BBB to the tumor sites and drop cytotoxic molecules there. The current status of research on NP for drug delivery to HGGs has been analyzed. The results indicate gold, lipids and proteins as three main materials featuring NP formulations for HGG treatment. Albeit specific drug targeting to HGG cells may have not been so far significantly improved, NP may help drugs crossing the BBB and enter the brain thus potentially fixing at least one part of the problem. FROM THE CLINICAL EDITOR: High grade gliomas (HGG) are very aggressive tumours and current therapy remains unsatisfactory. The advance in nanomedicine has allowed the development of novel treatment modalities. In this review article, the authors outlined the current status in using nanoparticle (NP)-based carriers for drug delivery to HGG. This should help readers to understand and develop ideas for further drug carrier designs.