Investigating survival, quality of life and cognition in PROton versus photon therapy for IDH-mutated diffuse grade 2 and 3 GLIOmas (PRO-GLIO): a randomised controlled trial in Norway and Sweden.

INTRODUCTION: The use of proton therapy increases globally despite a lack of randomised controlled trials demonstrating its efficacy and safety. Proton therapy enables sparing of non-neoplastic tissue from radiation. This is principally beneficial and holds promise of reduced long-term side effects. However, the sparing of seemingly non-cancerous tissue is not necessarily positive for isocitrate dehydrogenase (IDH)-mutated diffuse gliomas grade 2-3, which have a diffuse growth pattern. With their relatively good prognosis, yet incurable nature, therapy needs to be delicately balanced to achieve a maximal survival benefit combined with an optimised quality of life. METHODS AND ANALYSIS: PRO-GLIO (PROton versus photon therapy in IDH-mutated diffuse grade 2 and 3 GLIOmas) is an open-label, multicentre, randomised phase III non-inferiority study. 224 patients aged 18-65 years with IDH-mutated diffuse gliomas grade 2-3 from Norway and Sweden will be randomised 1:1 to radiotherapy delivered with protons (experimental arm) or photons (standard arm). First intervention-free survival at 2 years is the primary endpoint. Key secondary endpoints are fatigue and cognitive impairment, both at 2 years. Additional secondary outcomes include several survival measures, health-related quality of life parameters and health economy endpoints. ETHICS AND DISSEMINATION: To implement proton therapy as part of standard of care for patients with IDH-mutated diffuse gliomas grade 2-3, it should be deemed safe. With its randomised controlled design testing proton versus photon therapy, PRO-GLIO will provide important information for this patient population concerning safety, cognition, fatigue and other quality of life parameters. As proton therapy is considerably more costly than its photon counterpart, cost-effectiveness will also be evaluated. PRO-GLIO is approved by ethical committees in Norway (Regional Committee for Medical & Health Research Ethics) and Sweden (The Swedish Ethical Review Authority) and patient inclusion has commenced. Trial results will be published in international peer-reviewed journals, relevant conferences, national and international meetings and expert forums. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT05190172).

[Glioblastoma in adults]. / Glioblastom hos voksne.

Glioblastoma is the most common form of primary brain cancer in adults, and the disease has a serious prognosis. Although great progress has been made in molecular characteristics, no major breakthroughs in treatment have been achieved for many years. In this article we present a clinical review of current diagnostics and treatment, as well as the challenges and opportunities inherent in developing improved and more personalised treatment.

[Brain metastases ­ diagnostics and treatment] / Hjernemetastasar ­ diagnostikk og behandling.

An ageing population as well as improved diagnostics, monitoring and treatment mean that an increasing incidence of brain metastases can be expected. Patients with brain metastases were previously regarded as a homogenous group with a very poor prognosis. However, the current picture is more complex. The development of new treatment methods, better molecular understanding and personalised medicine require a focus on multidisciplinary collaboration to provide optimal treatment for individual patients. This clinical review article provides an overview of important factors related to the diagnosis and treatment of patients with brain metastases.

PKM2 Interacts With the Cdk1-CyclinB Complex to Facilitate Cell Cycle Progression in Gliomas.

PKM2 is a phosphotyrosine-binding glycolytic enzyme upregulated in many cancers, including glioma, and contributes to tumor growth by regulating cell cycle progression. We noted, however, that in multiple glioma cell lines, PKM2 knock-down resulted in an accumulation of cells in G2-M phase. Moreover, PKM2 knock-down decreased Cdk1 activity while introducing a constitutively active Cdk1 reversed the effects of PKM2 knock-down on cell cycle progression. The means by which PKM2 increases Cdk1 activity have not been described. Transient interaction of T14/Y15-phosphorylated Cdk1 with cyclin B allows Cdk7-mediated pT161 Cdk1 phosphorylation followed by cdc25C-mediated removal of pT14/Y15 and activation of Cdk1 in cycling cells. In the present course of investigation, PKM2 modulation did not influence Cdk7 activity, but phosphotyrosine binding forms of PKM2 co-immunoprecipitated with pY15-containing Cdk1-cyclinB and enhanced formation of active pT161 Cdk1-cyclin B complexes. Moreover, exogenous expression of phosphotyrosine binding forms of PKM2 reversed the effects of PKM2 knock-down on G2-M arrest. We here show that PKM2 binds and stabilize otherwise transient pY15-containing Cdk1-cyclinB complexes that in turn facilitate Cdk1-cyclin B activation and entry of cells into mitosis. These results, therefore, establish metabolic enzyme PKM2 as a direct interactor and activator of Cdk1-cyclin B complex and thereby directly controls mitotic progression and the growth of brain tumor cells.

Phosphoglycerate mutase 1 (PGAM1) overexpression promotes radio- and chemoresistance in gliomas by activating the DNA damage response.

The glycolytic enzyme PGAM1 is overexpressed in gliomas where it efficiently facilitates the repair of DNA damage. Mechanistically, PGAM1 prevents inactivation of the ataxia-telangiectasia mutated (ATM) signaling pathway by sequestering the wild-type p53-induced phosphatase 1 (WIP1) in the cytoplasm. Genetic inhibition of PGAM1 expression subsequently sensitizes glioma cells against irradiation and chemotherapy-induced DNA damage.

Phosphoglycerate Mutase 1 Activates DNA Damage Repair via Regulation of WIP1 Activity.

The metabolic enzyme phosphoglycerate mutase 1 (PGAM1) is overexpressed in several types of cancer, suggesting an additional function beyond its established role in the glycolytic pathway. We here report that PGAM1 is overexpressed in gliomas where it increases the efficiency of the DNA damage response (DDR) pathway by cytoplasmic binding of WIP1 phosphatase, thereby preventing WIP1 nuclear translocation and subsequent dephosphorylation of the ATM signaling pathway. Silencing of PGAM1 expression in glioma cells consequently decreases formation of γ-H2AX foci, increases apoptosis, and decreases clonogenicity following irradiation (IR) and temozolomide (TMZ) treatment. Furthermore, mice intracranially implanted with PGAM1-knockdown cells have significantly improved survival after treatment with IR and TMZ. These effects are counteracted by exogenous expression of two kinase-dead PGAM1 mutants, H186R and Y92F, indicating an important non-enzymatic function of PGAM1. Our findings identify PGAM1 as a potential therapeutic target in gliomas.

Rapid Conversion of Mutant IDH1 from Driver to Passenger in a Model of Human Gliomagenesis.

Missense mutations in the active site of isocitrate dehydrogenase 1 (IDH1) biologically and diagnostically distinguish low-grade gliomas and secondary glioblastomas from primary glioblastomas. IDH1 mutations lead to the formation of the oncometabolite 2-hydroxyglutarate (2-HG) from the reduction of α-ketoglutarate (α-KG), which in turn facilitates tumorigenesis by modifying DNA and histone methylation as well blocking differentiation processes. Although mutant IDH1 expression is thought to drive the gliomagenesis process, the extent to which it remains a viable therapeutic target remains unknown. To address this question, we exposed immortalized (p53/pRb deficient), untransformed human astrocytes to the mutant IDH1 inhibitor AGI-5198 prior to, concomitant with, or at intervals after, introduction of transforming mutant IDH1, then measured effects on 2-HG levels, histone methylation (H3K4me3, H3K9me2, H3K9me3, or H3K27me3), and growth in soft agar. Addition of AGI-5198 prior to, or concomitant with, introduction of mutant IDH1 blocked all mutant IDH1-driven changes, including cellular transformation. Addition at time intervals as short as 4 days following introduction of mutant IDH1 also suppressed 2-HG levels, but had minimal effects on histone methylation, and lost the ability to suppress clonogenicity in a time-dependent manner. Furthermore, in two different models of mutant IDH1-driven gliomagenesis, AGI-5198 exposures that abolished production of 2-HG also failed to decrease histone methylation, adherent cell growth, or anchorage-independent growth in soft agar over a prolonged period. These studies show although mutant IDH1 expression drives gliomagenesis, mutant IDH1 itself rapidly converts from driver to passenger. IMPLICATIONS: Agents that target mutant IDH may be effective for a narrow time and may require further optimization or additional therapeutics in glioma. Mol Cancer Res; 14(10); 976-83. ©2016 AACR.

The DNA repair protein ALKBH2 mediates temozolomide resistance in human glioblastoma cells.

INTRODUCTION: Glioblastoma multiforme (GBM; World Health Organization astrocytoma grade IV) is the most frequent and most malignant primary brain tumor in adults. Despite multimodal therapy, all such tumors practically recur during the course of therapy, causing a median survival of only 14.6 months in patients with newly diagnosed GBM. The present study was aimed at examining the expression of the DNA repair protein AlkB homolog 2 (ALKBH2) in human GBM and determining whether it could promote resistance to temozolomide chemotherapy. METHODS: ALKBH2 expression in GBM cell lines and in human GBM was determined by quantitative real-time PCR (qRT-PCR) and gene expression analysis, respectively. Drug sensitivity was assessed in GBM cells overexpressing ALKBH2 and in cells in which ALKBH2 expression was silenced by small-interfering (si)RNA. ALKBH2 expression following activation of the p53 pathway was examined by western blotting and qRT-PCR. RESULTS: ALKBH2 was abundantly expressed in established GBM cell lines and human GBM, and temozolomide exposure increased cellular ALKBH2 expression levels. Overexpression of ALKBH2 in the U87 and U251 GBM cell lines enhanced resistance to the methylating agents temozolomide and methyl methanesulfonate but not to the nonmethylating agent doxorubicin. Conversely, siRNA-mediated knockdown of ALKBH2 increased sensitivity of GBM cells to temozolomide and methyl methanesulfonate but not to doxorubicin or cisplatin. Nongenotoxic activation of the p53 pathway by the selective murine double minute 2 antagonist nutlin-3 caused a significant decrease in cellular ALKBH2 transcription levels. CONCLUSION: Our findings identify ALKBH2 as a novel mediator of temozolomide resistance in human GBM cells. Furthermore, we place ALKBH2 into a new cellular context by showing its regulation by the p53 pathway.

Tumor vasculature: the Achilles' heel of cancer?

INTRODUCTION: Tumor-associated angiogenesis is one of the essential hallmarks underlying cancer development and metastasis. Anti-angiogenic agents accordingly aim to restrain cancer progression by blocking the formation of new vessels, improving the delivery of chemotherapeutic agents to the tumor site and reducing the shedding of metastatic cells into the circulation. This review article addresses some key issues in the use of angiogenesis inhibitors in cancer. AREAS COVERED: The authors review the complex interactions between cell signaling pathways involved in tumor angiogenesis, and focus in particular on the molecular mechanisms that may induce resistance to angiogenesis inhibitors. They will also discuss some novel therapeutic strategies evolving within anti-angiogenic therapy such as the targeting of VEGFR-3, endothelial integrins and hepatocyte growth factor-MET signaling. EXPERT OPINION: Although anti-angiogenic therapy is targeted at the non-malignant part of the tumor, the intricate network of growth promoting signaling pathways and in particular the redundancy when single pathways are targeted in endothelial cells represents a major therapeutic obstacle. A key challenge will be to develop more efficient inhibitors, combined with an individualized approach based on each tumor's own endothelial signaling profile. Furthermore, reliable biomarkers which pinpoint those patients that will benefit from anti-angiogenic therapy need to be identified.

Molecular mechanisms of temozolomide resistance in glioblastoma multiforme.

Glioblastoma multiforme (GBM; WHO astrocytoma grade IV) is considered incurable owing to its inherently profound resistance towards current standards of therapy. Considerable effort is being devoted to identifying the molecular basis of temozolomide resistance in GBMs and exploring novel therapeutic regimens that may improve overall survival. Several independent DNA repair mechanisms that normally safeguard genome integrity can facilitate drug resistance and cancer cell survival by removing chemotherapy-induced DNA adducts. Furthermore, subpopulations of cancer stem-like cells have been implicated in the treatment resistance of several malignancies including GBMs. Thus, a growing number of molecular mechanisms contributing to temozolomide resistance are being uncovered in preclinical studies and, consequently, we are being presented with a broad range of potentially novel targets for therapy. A substantial future challenge is to successfully exploit the increasing molecular knowledge contributing to temozolomide resistance in robust clinical trials and to ultimately improve overall survival for GBM patients.

DNA repair and cancer stem-like cells--potential partners in glioma drug resistance?

Glioblastoma is the most malignant and frequent primary brain tumour in adults. Current treatment remains insufficient as these tumours display a diffuse infiltrative growth pattern and tend to recur despite extensive debulking surgery followed by radio- and chemotherapy. The alkylating agents carmustine (1,3-bis-(2-chloroethyl)-1-nitrosourea, or BCNU) and temozolomide (TMZ) are the drugs of choice for adjuvant glioma chemotherapy. However, several independent DNA repair mechanisms can restore the integrity of alkylated DNA bases, and thus contribute to drug resistance and subsequent therapy failure. Recent work suggests that glioblastomas develop as cellular and functional hierarchies through small subpopulations of stem cell-like cancer cells that are responsible for tumour initiation and maintenance. Such cells also appear to possess enhanced DNA repair capacity compared to other cells within the tumours. Challenges in glioblastoma therapy are to determine (1) whether the cancer stem-like cell subpopulations represent a clinically novel target for therapy, and (2) which additional treatment strategies should be applied to improve quality of life and prolong survival of glioblastoma patients. This review addresses clinically relevant mechanisms which contribute to glioma resistance towards current alkylating agent-based chemotherapy, and discusses related mechanisms and treatment strategies in the light of the cancer stem cell hypothesis.