Long-Term Tumor Control Following Targeted Alpha Therapy (TAT) of Low-Grade Gliomas (LGGs): A New Treatment Paradigm?

The median survival time has been reported to vary between 5 and 8 years in low-grade (WHO grade 2) astrocytoma, and between 10 and 15 years for grade 2 oligodendroglioma. Targeted alpha therapy (TAT), using the modified peptide vector [213Bi]Bi/[225Ac]Ac-DOTA-substance P, has been developed to treat glioblastoma (GBM), a prevalent malignant brain tumor. In order to assess the risk of late neurotoxicity, assuming that reduced tumor cell proliferation and invasion should directly translate into good responses in low-grade gliomas (LGGs), a limited number of patients with diffuse invasive astrocytoma (n = 8) and oligodendroglioma (n = 3) were offered TAT. In two oligodendroglioma patients, TAT was applied as a second-line treatment for tumor progression, 10 years after targeted beta therapy using [90Y]Y-DOTA-substance P. The radiopharmaceutical was locally injected directly into the tumor via a stereotactic insertion of a capsule-catheter system. The activity used for radiolabeling was 2-2.5 GBq of Bismuth-213 and 17 to 35 MBq of Actinium-225, mostly applied in a single fraction. The recurrence-free survival times were in the range of 2 to 16 years (median 11 years) in low-grade astrocytoma (n = 8), in which TAT was administered following a biopsy or tumor debulking. Regarding oligodendroglioma, the recurrence-free survival time was 24 years in the first case treated, and 4 and 5 years in the two second-line cases. In conclusion, TAT leads to long-term tumor control in the majority of patients with LGG, and recurrence has so far not manifested in patients with low-grade (grade 2) astrocytomas who received TAT as a first-line therapy. We conclude that targeted alpha therapy has the potential to become a new treatment paradigm in LGG.

Locoregional Treatment of Glioblastoma With Targeted α Therapy: [ 213 Bi]Bi-DOTA-Substance P Versus [ 225 Ac]Ac-DOTA-Substance P-Analysis of Influence Parameters.

BACKGROUND: Glioblastoma (GB) is the most malignant primary brain tumor. Therefore, introduction of new treatment options is critically important. The aim of this study was to assess local treatment with α emitters [ 213 Bi]Bi-DOTA-substance P (SP) and [ 225 Ac]Ac-DOTA-SP. METHODS: Treatment was performed as salvage therapy in patients with recurrent primary and secondary GB. [ 213 Bi]Bi-DOTA-SP with injected activity 1.85 GBq per cycle was used in 20 primary (48.2 ± 11.8 years old) and in 9 secondary (38.8 ± 10.8 years old) GB patients and [ 225 Ac]Ac-DOTA-SP in 15 primary (45.1 ± 9.9 years old) and in 6 secondary (37.8 ± 6.4 years old) GB patients with a dose escalation scheme (10, 20, and 30 MBq). RESULTS: Local treatment with [ 213 Bi]Bi-DOTA-SP and [ 225 Ac]Ac-DOTA-SP was well tolerated with only few adverse effects. There was no statistically significant difference between [ 213 Bi]Bi-DOTA-SP and [ 225 Ac]Ac-DOTA-SP groups in survival parameters. For primary GB, survival parameters of patients treated with [ 213 Bi]Bi-DOTA-SP and [ 225 Ac]Ac-DOTA-SP were as follows(in months): progression-free survival time, 2.7 versus 2.4; OS-d (overall survival from time of diagnosis to death from any cause), 23.6 versus 21.0; OS-t (overall survival from the start of treatment to death from any cause), 7.5 versus 5.0; and OS-r (overall survival from recurrence in primary tumors to death from any cause), 10.9 versus 12.0. Survival parameters of secondary GB patients treated with [ 213 Bi]Bi-DOTA-SP and [ 225 Ac]Ac-DOTA-SP were as follows (in months): progression-free survival time, 5.8 versus 2.4; OS-d, 52.3 versus 65.0; OS-t, 16.4 versus 16.0; and OS-c (overall survival from conversion into secondary GB multiforme to death from any cause), 18.4 versus 36.0. CONCLUSIONS: The similarity results of 213 Bi or 225 Ac may suggest that the local treatment of brain tumors can be greatly simplified. The experience to date shows that local radioisotope treatment of brain tumors requires further dosimetry studies, taking into account the complexity of biological processes.

Dose escalation study of targeted alpha therapy with [225Ac]Ac-DOTA-substance P in recurrence glioblastoma - safety and efficacy.

Glioblastoma is the most common and malignant primary brain tumour, with a poor prognosis. Introduction of new treatment options is critically important. The study aimed to assess the appropriateness of escalation doses and toxicity of [225Ac]Ac-DOTA-SP therapy. MATERIAL AND METHODS: A total of 21 patients (age of 43.0 ± 9.5 years), with histologically confirmed recurrent or conversion glioblastoma grade 4 following a standard therapy, have been included in the study. One to 2 intracavitary port-a-cath systems were stereotactically inserted. Patients were treated with escalation dose protocol with 10, 20 and 30 MBq per cycle totally 1-6 doses of [225Ac]Ac-DOTA-SP in 2-month intervals. Therapeutic response was monitored by clinical performance status and MRI imaging. RESULTS: Treatment was well tolerated with mostly mild temporary adverse effects (oedema, epileptic seizures, aphasia, hemiparesis) mainly in the group of patients treated with 30 MBq of [225Ac]Ac-DOTA-SP. Only one patient treated with 30 MBq revealed thrombopenia grade 3. There was no other grade 3 and 4 toxicity related to [225Ac]Ac-DOTA-treatment in all groups. The median overall survival time from the primary diagnosis (OS-d) was 35.0 months and from the diagnosis of the recurrence/conversion (OS-r/c) was 13.2 months. From the start of treatment with [225Ac]Ac-DOTA-SP, the median PFS was 2.4 months, and the OS-t was 9.0 months. There were no statistically significant differences between the investigated dose escalation groups. CONCLUSIONS: Treatment of recurrent glioblastoma with [225Ac]Ac-DOTA-SP is safe and well tolerated up to 30 MBq per cycle. The escalation dose protocol showed good tolerability. Only mild temporary adverse effects were observed. No remarkable haematological, kidney and liver toxicity was seen.

225Ac- and 213Bi-Substance P Analogues for Glioma Therapy.

Within the last decades, there has been no major improvement in treatment of patients with glioma, especially with glioblastoma multiforme (GBM) which is related to specific features of this tumor type, such as heterogeneity at the macroscopic, microscopic and genetic level, the infiltrative nature of tumors and the obstacle of the brain-blood barrier which limits the accessability of most drugs. The current standard of care is surgical resection, followed by radio- and chemotherapy. After first-line treatment of the primary lesion, tumor recurrence is diagnosed in virtually all GBM patients. Treatment of tumor recurrence represents a challenging clinical task. Surgical resection to relief symptoms of mass effect and/or salvage chemotherapy are often considered as last therapeutic option. A new treatment option is urgently needed. Targeted alpha therapy with an intratumoral injection of 213Bi-DOTA-Substance P (SP) or 225Ac-DOTAGA-Substance P has been introduced into the therapeutic armamentarium of recurrent GBM. There are many advantages of using SP such as very high prevalence of increased NK-1 expression in GBM cells, regardless of the degree of malignancy, and expression of the NK-1 receptor system not only on the membrane of cancer cells but also strong expression of NK1 receptors within the tumor neovasculature suggesting concomitant targeting of vascular and neoplastic structures. Radioisotopes with different physical properties, mainly beta-emitting metallic radionuclides, were implemented for brain tumor treatment. Based on their radiophysical properties, however, alpha emitters exhibit more promising properties. In investigator-initiated phase I and II studies, targeted alpha therapy using Bi-213/Ac-225 radiolabeled Substance P for malignant gliomas compare favorably with standard therapy, with the limitation that no large controlled series have so far been generated. Further development should focus on the improvement of the biological and chemical properties of the compound and the application by dedicated catheter systems to improve the intratumoral distribution of the radiopharmaceutical within growth and infiltrative zone of these glial neoplasms.

Long-Term Results of Targeted Low-Grade Glioma Treatment with 213Bi-DOTA-[Thi8,Met(O2)11]-Substance P.

The aim was to evaluate long-term effectiveness, functional outcome, and side effects of targeted α radiotherapy as an alternative treatment for low-grade gliomas (LGGs) in eloquent brain areas. Five patients with gliomas World Health Organization (WHO) II-IV were treated with tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-213Bi substance P. In this study, the LGG patients' (WHO II) clinical and radiological long-term outcome was examined. Ten years after treatment with DOTA-213Bi substance P, both LGG patients are still alive without evidence for tumor recurrence and without new functional deficits. Targeted α radiotherapy of LGG might have the potential of long-term tumor control, due to the short tissue range of α particles especially for eloquently located LGG.

Safety and efficacy of targeted alpha therapy with 213Bi-DOTA-substance P in recurrent glioblastoma.

Treatment options for recurrent glioblastoma multiforme (GBM) are very limited. GBM cells express high levels of the GPCR neurokinin type 1 receptor (NK-1R), and a modified substance P can be used as its ligand for the tumor cell targeting. Targeted alpha therapy with DOTA-Substance P labeled with the short range alpha emitter 213Bi allows for selective irradiation and killing of tumor cells. MATERIAL AND METHODS: Twenty patients with recurrent GBM were included into the study following a standard therapy. 1-2 intracavitary or intratumoral port-a-cath systems were stereotactically inserted. Patients were treated with 1-7 doses of 213Bi-DOTA-Substance P (213Bi-DOTA-SP) in 2-month intervals. 68Ga-DOTA-Substance P (68Ga-DOTA-SP) was co-injected with 213Bi-DOTA-SP to assess the biodistribution using PET/CT. Therapeutic response was monitored with performance status and MRI imaging. RESULTS: Treatment with activity up to 11.2 GBq 213Bi-DOTA-SP was well tolerated with only mild and transient adverse reactions. The median progression free survival was 2.7 months. The median overall survival from the first diagnosis was 23.6 months and median survival after recurrence was 10.9 months. The median survival time from the start of 213Bi-DOTA-SP was 7.5 months. CONCLUSIONS: Treatment of recurrent GBM with 213Bi-DOTA-SP is safe and well tolerated. The median overall survival after recurrence of 10.9 months compares favorably to the available alternative treatment options. Once the supply of high activity 225Ac/213Bi radionuclide generators is secured, targeted alpha therapy with 213Bi-DOTA-SP may evolve as a promising novel option to treat recurrent GBM.

Prolonged survival in secondary glioblastoma following local injection of targeted alpha therapy with 213Bi-substance P analogue.

BACKGROUND: Glioblastoma multiforme (GBM), the most common malignant brain tumor, mainly manifests as a primary de novo and less frequently as a secondary glial neoplasm. GBM has been demonstrated to overexpress the NK-1 receptor and substance P can be used as a ligand for targeted therapy. Alpha emitters, e.g. 213Bi, that deposit their high energy within a short range allow the selective irradiation of tumor cells while sparing adjacent neuronal structures. MATERIAL AND METHODS: Among 50 glioma patients of different subtypes that have to date been treated with targeted alpha therapy at the Medical University Warsaw, we report here the data on nine patients with secondary GBM. Following surgery, chemo- and radiotherapy, recurrent GBM was treated by intracavitary injection of 1-6 doses of 0.9-2.3 GBq 213Bi- DOTA-[Thi8,Met(O2)11]-substance P (213Bi-DOTA-SP) in 2-month intervals. 68Ga-DOTA-[Thi8,Met(O2)11]-substance P (68Ga-DOTA-SP) was co-injected with the therapeutic doses to assess biodistribution using PET/CT. Therapeutic response was monitored with MRI. RESULTS: Treatment with activities ranging from 1.4 to 9.7 (median 5.8) GBq 213Bi- DOTA-SP was well tolerated with only mild transient adverse reactions, mainly headaches due to a transient perfocal edema reaction. The median progression free survival and overall survival time following the initiation of alpha therapy was 5.8 and 16.4 months, respectively. The median overall survival time from the first diagnosis was 52.3 months. Two out of nine patients are still alive 39 and 51 months, respectively, after the initiation of the therapy. CONCLUSIONS: Targeted alpha therapy of secondary GBM with 213Bi-DOTA-SP is safe and well tolerated and may evolve as a promising novel therapeutic option for secondary GBM.

SYK inhibition blocks proliferation and migration of glioma cells and modifies the tumor microenvironment.

Background: Glioblastoma (GBM) is one of the most aggressive human brain tumors, with a median survival of 15-18 months. There is a desperate need to find novel therapeutic targets. Various receptor protein kinases have been identified as potential targets; however, response rates in clinical studies have been somewhat disappointing. Targeting the spleen tyrosine kinase (SYK), which acts downstream of a range of oncogenic receptors, may therefore show more promising results. Methods: Kinase expression of brain tumor samples including GBM and low-grade tumors were compared with normal brain and normal human astrocytes by microarray analysis. Furthermore, SYK, LYN, SLP76, and PLCG2 protein expressions were analyzed by immunohistochemistry, western blot, and immunofluorescence of additional GBM patient samples, murine glioma samples, and cell lines. SYK was then blocked chemically and genetically in vitro and in vivo in 2 different mouse models. Multiphoton intravital imaging and multicolor flow cytometry were performed in a syngeneic immunocompetent C57BL/6J mouse GL261 glioma model to study the effect of these inhibitors on the tumor microenvironment. Results: SYK, LYN, SLP76, and PLCG2 were found expressed in human and murine glioma samples and cell lines. SYK inhibition blocked proliferation, migration, and colony formation. Flow cytometric and multiphoton imaging imply that targeting SYK in vivo attenuated GBM tumor growth and invasiveness and reduced B and CD11b+ cell mobility and infiltration. Conclusions: Our data suggest that gliomas express a SYK signaling network important in glioma progression, inhibition of which results in reduced invasion with slower tumor progression.

Targeted Radiolabeled Compounds in Glioma Therapy.

Malignant gliomas of World Health Organization (WHO) grades II-IV represent the largest entity within the group of intrinsic brain tumors and are graded according to their pathophysiological features with survival times between more than 10 years (WHO II) and only several months (WHO IV). Gliomas arise from astrocytic or oligodendrocytic precursor cells and exhibit an infiltrative growth pattern lacking a clearly identifiable tumor border. The development of effective treatment strategies of the invasive tumor cell front represents the main challenge in glioma therapy. The therapeutic standard consists of surgical resection and, depending on the extent of resection and WHO grade, adjuvant external beam radiotherapy or systemic chemotherapy. Within the last decades, there has been no major improvement of the prognosis of patients with glioma. The consistent overexpression of neurokinin type 1 receptors in gliomas WHO grades II-IV has been used to develop a therapeutic substance P-based targeting system. A substance P-analogue conjugated to the DOTA or DOTAGA chelator has been labeled with different alpha-particle or beta-particle emitting radionuclides for targeted glioma therapy. The radiopharmaceutical has been locally injected into the tumors or the resection cavity. In several clinical studies, the methodology has been examined in adjuvant and neoadjuvant clinical settings. Although no large controlled series have so far been generated, the results of radiolabeled substance P-based targeted glioma therapy compare favorably with standard therapy. Recently, labeling with the alpha particle emitting Bi-213 has been found to be promising due to the high linear energy transfer and the very short tissue range of 0.08 mm. Further development needs to focus on the improvement of the stability of the compound and the application by dedicated catheter systems to improve the intratumoral distribution of the radiopharmaceutical within the prognostically critical infiltrative growing zone of the glioma.

90Y-DOTATOC as a Therapeutic Option for Complex Recurrent or Progressive Meningiomas.

UNLABELLED: The standard treatment of meningiomas is surgery or radiotherapy. Complex, especially recurrent or progressive cases, may exhibit tumor growth involving critical neurovascular structures or diffuse growth, resulting in limited efficacy and higher risk of standard treatment. We evaluated whether somatostatin receptor-targeted radionuclide therapy with (90)Y-DOTATOC may be a therapeutic option. METHODS: Fifteen patients with recurrent or progressive meningiomas after multimodal pretreatment or unfavorable medical risk profile were treated with systemic (90)Y-DOTATOC. Endpoints were progression-free survival and toxicity. RESULTS: Usually applied doses were 7,400 MBq/m(2) of (90)Y-DOTATOC in 2 fractions. Mean observation time was 49.7 mo (range, 12-137 mo). Overall median progression-free survival was at least 24 mo. Toxicity was moderate, mostly hematologic (n = 8) and transient. CONCLUSION: (90)Y-DOTATOC therapy is feasible and may represent a promising second- or third-line option for complex meningiomas, which are progressive or otherwise not treatable with a reasonable risk-benefit ratio.

MNK1 pathway activity maintains protein synthesis in rapalog-treated gliomas.

High levels of mammalian target of rapamycin complex 1 (mTORC1) activity in malignant gliomas promote tumor progression, suggesting that targeting mTORC1 has potential as a therapeutic strategy. Remarkably, clinical trials in patients with glioma revealed that rapamycin analogs (rapalogs) have limited efficacy, indicating activation of resistance mechanisms. Targeted depletion of MAPK-interacting Ser/Thr kinase 1 (MNK1) sensitizes glioma cells to the mTORC1 inhibitor rapamycin through an indistinct mechanism. Here, we analyzed how MNK1 and mTORC1 signaling pathways regulate the assembly of translation initiation complexes, using the cap analog m7GTP to enrich for initiation complexes in glioma cells followed by mass spectrometry-based quantitative proteomics. Association of eukaryotic translation initiation factor 4E (eIF4E) with eIF4E-binding protein 1 (4EBP1) was regulated by the mTORC1 pathway, whereas pharmacological blocking of MNK activity by CGP57380 or MNK1 knockdown, along with mTORC1 inhibition by RAD001, increased 4EBP1 binding to eIF4E. Furthermore, combined MNK1 and mTORC1 inhibition profoundly inhibited 4EBP1 phosphorylation at Ser65, protein synthesis and proliferation in glioma cells, and reduced tumor growth in an orthotopic glioblastoma (GBM) mouse model. Immunohistochemical analysis of GBM samples revealed increased 4EBP1 phosphorylation. Taken together, our data indicate that rapalog-activated MNK1 signaling promotes glioma growth through regulation of 4EBP1 and indicate a molecular cross-talk between the mTORC1 and MNK1 pathways that has potential to be exploited therapeutically.

Erlotinib resistance in EGFR-amplified glioblastoma cells is associated with upregulation of EGFRvIII and PI3Kp110δ.

BACKGROUND: The treatment efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors like erlotinib has not met expectations for glioblastoma therapy, even for EGFR-overexpressing tumors. We determined possible mechanisms of therapy resistance using the unique BS153 glioblastoma cell line, which has retained amplification of the egfr gene and expression of EGFR variant (v)III. METHODS: Functional effects of erlotinib, gefitinib, and cetuximab on BS153 proliferation, migration, and EGFR-dependent signal transduction were systematically compared in vitro. The tumor-initiating capacity of parental and treatment-resistant BS153 was studied in Naval Medical Research Institute/Foxn1(nu) mice. Potential mediators of resistance were knocked down using small interfering (si)RNA. RESULTS: Erlotinib and gefitinib inhibited proliferation and migration of BS153 in a dose-dependent manner, whereas cetuximab had no effect. BS153 developed resistance to erlotinib (BS153(resE)) but not to gefitinib. Resistance was associated with strong upregulation of EGFRvIII and subsequent activation of the phosphatidylinositol-3-OH kinase (PI3K) pathway in BS153(resE) and an increased expression of the regulatory 110-kDa delta subunit of PI3K (p110δ). Knockdown of EGFRvIII in BS153(resE) largely restored sensitivity to erlotinib. Targeting PI3K pharmacologically caused a significant decrease in cell viability, and specifically targeting p110δ by siRNA partially restored erlotinib sensitivity in BS153(resE). In vivo, BS153 formed highly invasive tumors with an unusual growth pattern, displaying numerous satellites distant from the initial injection site. Erlotinib resistance led to delayed onset of tumor growth as well as prolonged overall survival of mice without changing tumor morphology. CONCLUSIONS: EGFRvIII can mediate resistance to erlotinib in EGFR-amplified glioblastoma via an increase in PI3Kp110δ. Interfering with PI3Kp110δ can restore sensitivity toward the tyrosine kinase inhibitor.

Deltex-1 activates mitotic signaling and proliferation and increases the clonogenic and invasive potential of U373 and LN18 glioblastoma cells and correlates with patient survival.

Glioblastoma (GBM) is a highly malignant primary tumor of the central nervous system originating in glial cells. GBM results in more years of life lost than any other cancer type. Low levels of Notch receptor expression correlates with prolonged survival in various high grade gliomas independent of other markers. Different downstream pathways of Notch receptors have been identified. We tested if the Notch/Deltex pathway, which is distinct from the canonical, CSL-mediated pathway, has a role in GBM. We show that the alternative or non-canonical Notch pathway functioning through Deltex1 (DTX1) mediates key features of glioblastoma cell aggressiveness. For example, DTX1 activates the RTK/PI3K/PKB and the MAPK/ERK mitotic pathways and induces anti-apoptotic Mcl-1. The clonogenic and growth potential of established glioma cells correlated with DTX1 levels. Microarray gene expression analysis further identified a DTX1-specific, MAML1-independent transcriptional program - including microRNA-21- which is functionally linked to the changes in tumor cell aggressiveness. Over-expression of DTX1 increased cell migration and invasion correlating to ERK activation, miR-21 levels and endogenous Notch levels. In contrast to high and intermediate expressors, patients with low DTX1 levels have a more favorable prognosis. The alternative Notch pathway via DTX1 appears to be an oncogenic factor in glioblastoma and these findings offer new potential therapeutic targets.

Anisotropic phantom measurements for quality assured use of diffusion tensor imaging in clinical practice.

BACKGROUND: Diffusion-weighted magnetic resonance imaging (MRI) is being increasingly applied in clinical practice, for example in neuronavigation and in modern radiation treatment planning. Quality assurance (QA) is therefore important to avoid clinical errors. PURPOSE: To compare four analytical programs and a neuronavigation tool to evaluate our in-house diffusion-weighted imaging protocol in order to be able to implement diffusion tensor imaging (DTI) into clinical practice. MATERIAL AND METHODS: A phantom containing crossing fibers was used for the QA. Fiber tracking and fractional anisotropy (FA) analyses were performed, and the geometrical resolution was verified using the phantom. RESULTS: FA results were reproducible within each program and no significant differences between programs were observed. Also, no significant differences in FA values were found when comparing the results between the four software programs. Geometrical resolution of the anatomical data-set was satisfactory; however the crossing of the fibers was not accurately represented by three of the four programs. CONCLUSION: Phantom QA is necessary before using DTI for novel procedures to identify the uncertainties associated with DTI data. It is important to remember that the results are software-dependent and that representation of the tracts may vary between software products. We therefore recommend caution with regard to the application of fiber tracking results intraoperatively when dealing with abnormal fiber tract anatomy.

Pathway analysis of glioblastoma tissue after preoperative treatment with the EGFR tyrosine kinase inhibitor gefitinib--a phase II trial.

Amplification of the epidermal growth factor receptor (EGFR) gene is one of the most common oncogenic alterations in glioblastoma (45%) making it a prime target for therapy. However, small molecule inhibitors of the EGFR tyrosine kinase showed disappointing efficacy in clinical trials for glioblastoma. Here we aimed at investigating the molecular effects of the tyrosine kinase inhibitor gefitinib on the EGFR signaling pathway in human glioblastoma. Twenty-two patients selected for reoperation of recurrent glioblastoma were treated within a phase II trial for 5 days with 500 mg gefitinib before surgery followed by postoperative gefitinib until recurrence. Resected glioblastoma tissues exhibited high concentrations of gefitinib (median, 4.1 µg/g), 20 times higher than respective plasma. EGFR-pathway activity was evaluated with phosphorylation-specific assays. The EGFR was efficiently dephosphorylated in treated patients as compared to a control cohort of 12 patients. However, no significant effect on 12 pathway constituents was detected. In contrast, in vitro treatment of a glioblastoma cell line, BS-153, with endogenous EGFRwt amplification and EGFRvIII expression resulted not only in dephosphorylation of the EGFR, but also of key regulators in the pathway such as AKT. Treating established xenografts of the same cell line as an in vivo model showed dephosphorylation of the EGFR without affecting downstream signal transductors, similar to the human glioblastoma. Taken together, gefitinib reaches high concentrations in the tumor tissue and efficiently dephosphorylates its target. However, regulation of downstream signal transducers in the EGFR pathway seems to be dominated by regulatory circuits independent of EGFR phosphorylation.

MAP kinase-interacting kinase 1 regulates SMAD2-dependent TGF-ß signaling pathway in human glioblastoma.

Glioblastoma multiforme (GBM) is the most common aggressive brain cancer with a median survival of approximately 1 year. In a search for novel molecular targets that could be therapeutically developed, our kinome-focused microarray analysis identified the MAP (mitogen-activated protein) kinase-interacting kinase 1 (MNK1) as an attractive theranostic candidate. MNK1 overexpression was confirmed in both primary GBMs and glioma cell lines. Inhibition of MNK1 activity in GBM cells by the small molecule CGP57380 suppressed eIF4E phosphorylation, proliferation, and colony formation whereas concomitant treatment with CGP57380 and the mTOR inhibitor rapamycin accentuated growth inhibition and cell-cycle arrest. siRNA-mediated knockdown of MNK1 expression reduced proliferation of cells incubated with rapamycin. Conversely, overexpression of full-length MNK1 reduced rapamycin-induced growth inhibition. Analysis of polysomal profiles revealed inhibition of translation in CGP57380 and rapamycin-treated cells. Microarray analysis of total and polysomal RNA from MNK1-depleted GBM cells identified mRNAs involved in regulation of TGF-ß pathway. Translation of SMAD2 mRNA as well as TGF-ß-induced cell motility and vimentin expression was regulated by MNK1 signaling. Tissue microarray analysis revealed a positive correlation between the immunohistochemical staining of MNK1 and SMAD2. Taken together, our findings offer insights into how MNK1 pathways control translation of cancer-related mRNAs including SMAD2, a key component of the TGF-ß signaling pathway. Furthermore, they suggest MNK1-controlled translational pathways in targeted strategies to more effectively treat GBM.

SMOC1 is a tenascin-C interacting protein over-expressed in brain tumors.

Tenascin-C is an extracellular matrix protein over-expressed in a large variety of cancers. In the present study, we aimed at identifying new interactors of tenascin-C by purifying secreted proteins on a tenascin-C affinity column. Analysis of eluates by mass spectrometry revealed phosphoglycerate kinase 1, clusterin, fibronectin, SPARC-related modular calcium-binding protein 1 (SMOC1) and nidogen-2 as potential interactors of tenascin-C. The interaction between tenascin-C and SMOC1 was confirmed by co-immunoprecipitation and further analyzed by Surface Plasmon Resonance Spectroscopy, which revealed an apparent dissociation constant (K(D)) value of 2.59∗10(-9)M. Further analyses showed that this binding is reduced in the presence of EDTA. To investigate whether SMOC1 itself could be over-expressed in the context of tumorigenesis, we analyzed data of two independent RNA profiling studies and found that mRNA levels of SMOC1 are significantly increased in oligodendrogliomas compared to control brain samples. In support of these data, western blot analysis of protein extracts from 12 oligodendrogliomas, 4 astrocytomas and 13 glioblastomas revealed elevated levels compared to healthy brain extract. Interestingly, cell migration experiments revealed that SMOC1 can counteract the chemo-attractive effect of tenascin-C on U87 glioma cells. The present study thus identified SMOC1 as a new cancer-associated protein capable of interacting with tenascin-C in vitro.

Notch signaling in glioblastoma: a developmental drug target?

Malignant gliomas are among the most devastating tumors for which conventional therapies have not significantly improved patient outcome. Despite advances in imaging, surgery, chemotherapy and radiotherapy, survival is still less than 2 years from diagnosis and more targeted therapies are urgently needed. Notch signaling is central to the normal and neoplastic development of the central nervous system, playing important roles in proliferation, differentiation, apoptosis and cancer stem cell regulation. Notch is also involved in the regulation response to hypoxia and angiogenesis, which are typical tumor and more specifically glioblastoma multiforme (GBM) features. Targeting Notch signaling is therefore a promising strategy for developing future therapies for the treatment of GBM. In this review we give an overview of the mechanisms of Notch signaling, its networking pathways in gliomas, and discuss its potential for designing novel therapeutic approaches.

Copeptin is associated with mortality and outcome in patients with acute intracerebral hemorrhage.

BACKGROUND: Spontaneous intracerebral hemorrhage (ICH) accounts for a high mortality and morbidity. Early prediction of outcome is crucial for optimized care and treatment decision. Copeptin, the C-terminal part of provasopressin, has emerged as a new prognostic marker in a variety of diseases, but its prognostic value in ICH is unknown. METHODS: In 40 consecutive patients who were admitted to the hospital within 72 hours after a spontaneous ICH, the plasma copeptin level was measured with a sandwich immunoassay upon admission. The prognostic value of copeptin to predict 30 day mortality and functional outcome after 90 days was assessed. A favorable outcome was defined as a Barthel score above 85 and a score below 3 on the Modified Rankin Scale. RESULTS: Copeptin correlated positively with hematoma volume (r = 0.32, p < 0.05) and negatively with the Glasgow Coma Scale (GCS) on admission (r = -0.35, p < 0.05). Copeptin levels were higher in patients who died within 30 days than in 30-day survivors (179.0 pmol/l (IQR 33.7- 566.0) vs. 12.9 pmol/l (IQR 5.2 - 42.8), p = 0.003). Copeptin levels were also higher in patients with an unfavorable functional outcome at 90 days compared to patients with a favorable outcome (32.4 pmol/l (IQR 9.5-97.8) vs. 11.9 pmol/l (IQR 3.2-19.8), p = 0.04). For the prediction of death, receiver-operating-characteristics analysis revealed an area under the curve (AUC) for copeptin of 0.88 (95%CI 0.75-1.00). The predictive value of the copeptin concentration was thus similar to that of GCS (AUC 0.82 (95%CI 0.59-1.00) p = 0.53), of the ICH Score (AUC 0.89, (95%CI 0.76-1.00), p = 0.94) and the ICH Grading Scale (AUC 0.86 (95%CI 0.69-1.00), p = 0.81). CONCLUSIONS: Copeptin is a new prognostic marker in patients with an ICH. If this finding can be confirmed in larger studies, copeptin might be an additional valuable tool for risk stratification and decision-making in the acute phase of ICH.