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Walter B, Hirsch S, Kuhlburger L, Stahl A, Schnabel L, Wisser S, Haeusser LA, Tsiami F, Plöger S, Aghaallaei N, Dick AM, Skokowa J, Schmees C, Templin M, Schenke-Layland K, Tatagiba M, Nahnsen S, Merk DJ, Tabatabai G. Functionally-instructed modifiers of response to ATR inhibition in experimental glioma. J Exp Clin Cancer Res 2024; 43:77. [PMID: 38475864 DOI: 10.1186/s13046-024-02995-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 02/25/2024] [Indexed: 03/14/2024] Open
Abstract
BACKGROUND The DNA damage response (DDR) is a physiological network preventing malignant transformation, e.g. by halting cell cycle progression upon DNA damage detection and promoting DNA repair. Glioblastoma are incurable primary tumors of the nervous system and DDR dysregulation contributes to acquired treatment resistance. Therefore, DDR targeting is a promising therapeutic anti-glioma strategy. Here, we investigated Ataxia telangiectasia and Rad3 related (ATR) inhibition (ATRi) and functionally-instructed combination therapies involving ATRi in experimental glioma. METHODS We used acute cytotoxicity to identify treatment efficacy as well as RNAseq and DigiWest protein profiling to characterize ATRi-induced modulations within the molecular network in glioma cells. Genome-wide CRISPR/Cas9 functional genomic screens and subsequent validation with functionally-instructed compounds and selected shRNA-based silencing were employed to discover and investigate molecular targets modifying response to ATRi in glioma cell lines in vitro, in primary cultures ex vivo and in zebrafish and murine models in vivo. RESULTS ATRi monotherapy displays anti-glioma efficacy in vitro and ex vivo and modulates the molecular network. We discovered molecular targets by genome-wide CRISPR/Cas9 loss-of-function and activation screens that enhance therapeutic ATRi effects. We validated selected druggable targets by a customized drug library and functional assays in vitro, ex vivo and in vivo. CONCLUSION In conclusion, our study leads to the identification of novel combination therapies involving ATRi that could inform future preclinical studies and early phase clinical trials.
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Affiliation(s)
- Bianca Walter
- Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Sophie Hirsch
- Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Laurence Kuhlburger
- Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Quantitative Biology Center, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Biomedical Data Science, Department of Computer Science, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Aaron Stahl
- NMI Natural and Medical Sciences Institute, University of Tübingen, 72770, Reutlingen, Germany
| | - Leonard Schnabel
- Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Silas Wisser
- Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Lara A Haeusser
- Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- German Consortium for Translational Cancer Research (DKTK), Partner Site Tübingen, 72076, Tübingen, Germany
| | - Foteini Tsiami
- Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Sarah Plöger
- NMI Natural and Medical Sciences Institute, University of Tübingen, 72770, Reutlingen, Germany
| | - Narges Aghaallaei
- Division of Translational Oncology, Department of Internal Medicine II, University Hospital Tübingen, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Advaita M Dick
- Division of Translational Oncology, Department of Internal Medicine II, University Hospital Tübingen, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Julia Skokowa
- Division of Translational Oncology, Department of Internal Medicine II, University Hospital Tübingen, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Christian Schmees
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- NMI Natural and Medical Sciences Institute, University of Tübingen, 72770, Reutlingen, Germany
| | - Markus Templin
- NMI Natural and Medical Sciences Institute, University of Tübingen, 72770, Reutlingen, Germany
| | - Katja Schenke-Layland
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- NMI Natural and Medical Sciences Institute, University of Tübingen, 72770, Reutlingen, Germany
- Institute of Biomedical Engineering, Department for Medical Technologies and Regenerative Medicine, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Marcos Tatagiba
- Center for Neuro-Oncology, Comprehensive Cancer Center Tübingen-Stuttgart, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Department of Neurosurgery, University Hospital Tübingen, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Sven Nahnsen
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Quantitative Biology Center, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Biomedical Data Science, Department of Computer Science, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Daniel J Merk
- Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Ghazaleh Tabatabai
- Department of Neurology & Interdisciplinary Neuro-Oncology, University Hospital Tübingen, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tübingen, 72076, Tübingen, Germany.
- Cluster of Excellence (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", Eberhard Karls University Tübingen, 72076, Tübingen, Germany.
- German Consortium for Translational Cancer Research (DKTK), Partner Site Tübingen, 72076, Tübingen, Germany.
- Center for Neuro-Oncology, Comprehensive Cancer Center Tübingen-Stuttgart, Eberhard Karls University Tübingen, 72076, Tübingen, Germany.
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Zhang W, Vaubel RA, Oh JH, Mladek AC, Talele S, Zhang W, Waller KL, Burgenske DM, Sarkaria JN, Elmquist WF. Delivery versus Potency in Treating Brain Tumors: BI-907828, a MDM2-p53 Antagonist with Limited BBB Penetration but Significant In Vivo Efficacy in Glioblastoma. Mol Cancer Ther 2024; 23:47-55. [PMID: 37828724 PMCID: PMC10843165 DOI: 10.1158/1535-7163.mct-23-0217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 08/03/2023] [Accepted: 10/10/2023] [Indexed: 10/14/2023]
Abstract
MDM2-p53 inhibition may be effective in glioblastoma (GBM). This study evaluates the pharmacokinetics/pharmacodynamics of BI-907828, a potent antagonist of MDM2, in GBM, and demonstrates a translational paradigm with a focus on a unified "Delivery - Potency - Efficacy" relationship in drug development for central nervous system(CNS) tumors. BI-907828 was tested for cytotoxicity and MDM2-p53 pathway inhibition. Systemic pharmacokinetics and transport mechanisms controlling CNS distribution were evaluated in mice. BI-907828 free fractions in cell media, mouse and human specimens were measured to determine "active" unbound concentrations. Efficacy measures, including overall survival and target expression were assessed in mouse orthotopic GBM xenografts. BI-907828 exhibited potent inhibition of MDM2-p53 pathway and promoted cell death in GBM TP53 wild-type cells. MDM2-amplified cells are highly sensitive to BI-907828, with an effective unbound concentration of 0.1 nmol/L. The CNS distribution of BI-907828 is limited by blood-brain barrier (BBB) efflux mediated by P-gp, resulting in a Kp,uu_brain of 0.002. Despite this seemingly "poor" BBB penetration, weekly administration of 10 mg/kg BI-907828 extended median survival of orthotopic GBM108 xenografts from 28 to 218 days (P < 0.0001). This excellent efficacy can be attributed to high potency, resulting in a limited, yet effective, exposure in the CNS. These studies show that efficacy of BI-907828 in orthotopic models is related to high potency even though its CNS distribution is limited by BBB efflux. Therefore, a comprehensive understanding of all aspects of the "Delivery - Potency - Efficacy" relationship is warranted in drug discovery and development, especially for treatment of CNS tumors.
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Affiliation(s)
- Wenjuan Zhang
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota
| | | | - Ju-Hee Oh
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota
| | - Ann C. Mladek
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Surabhi Talele
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota
| | - Wenqiu Zhang
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota
| | - Katie L. Waller
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - Jann N. Sarkaria
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - William F. Elmquist
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota
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Zhang W, Oh JH, Zhang W, Rathi S, Le J, Talele S, Sarkaria JN, Elmquist WF. How Much is Enough? Impact of Efflux Transporters on Drug delivery Leading to Efficacy in the Treatment of Brain Tumors. Pharm Res 2023; 40:2731-2746. [PMID: 37589827 PMCID: PMC10841221 DOI: 10.1007/s11095-023-03574-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 07/19/2023] [Indexed: 08/18/2023]
Abstract
The lack of effective chemotherapeutic agents for the treatment of brain tumors is a serious unmet medical need. This can be attributed, in part, to inadequate delivery through the blood-brain barrier (BBB) and the tumor-cell barrier, both of which have active efflux transporters that can restrict the transport of many potentially effective agents for both primary and metastatic brain tumors. This review briefly summarizes the components and function of the normal BBB with respect to drug penetration into the brain and the alterations in the BBB due to brain tumor that could influence drug delivery. Depending on what is rate-limiting a compound's distribution, the limited permeability across the BBB and the subsequent delivery into the tumor cell can be greatly influenced by efflux transporters and these are discussed in some detail. Given these complexities, it is necessary to quantify the extent of brain distribution of the active (unbound) drug to compare across compounds and to inform potential for use against brain tumors. In this regard, the metric, Kp,uu, a brain-to-plasma unbound partition coefficient, is examined and its current use is discussed. However, the extent of active drug delivery is not the only determinant of effective therapy. In addition to Kp,uu, drug potency is an important parameter that should be considered alongside drug delivery in drug discovery and development processes. In other words, to answer the question - How much is enough? - one must consider how much can be delivered with how much needs to be delivered.
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Affiliation(s)
- Wenjuan Zhang
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA
| | - Ju-Hee Oh
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA
| | - Wenqiu Zhang
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA
| | - Sneha Rathi
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA
| | - Jiayan Le
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA
| | - Surabhi Talele
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA
| | - Jann N Sarkaria
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN, USA
| | - William F Elmquist
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA.
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Talele S, Zhang W, Chen J, Gupta SK, Burgenske DM, Sarkaria JN, Elmquist WF. Central Nervous System Distribution of the Ataxia-Telangiectasia Mutated Kinase Inhibitor AZD1390: Implications for the Treatment of Brain Tumors. J Pharmacol Exp Ther 2022; 383:91-102. [PMID: 36137710 PMCID: PMC9513858 DOI: 10.1124/jpet.122.001230] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 08/01/2022] [Indexed: 08/18/2023] Open
Abstract
Effective drug delivery to the brain is critical for the treatment of glioblastoma (GBM), an aggressive and invasive primary brain tumor that has a dismal prognosis. Radiation therapy, the mainstay of brain tumor treatment, works by inducing DNA damage. Therefore, inhibiting DNA damage response (DDR) pathways can sensitize tumor cells to radiation and enhance cytotoxicity. AZD1390 is an inhibitor of ataxia-telangiectasia mutated kinase, a critical regulator of DDR. Our in vivo studies in the mouse indicate that delivery of AZD1390 to the central nervous system (CNS) is restricted due to active efflux by P-glycoprotein (P-gp). The free fraction of AZD1390 in brain and spinal cord were found to be low, thereby reducing the partitioning of free drug to these organs. Coadministration of an efflux inhibitor significantly increased CNS exposure of AZD1390. No differences were observed in distribution of AZD1390 within different anatomic regions of CNS, and the functional activity of P-gp and breast cancer resistance protein also remained the same across brain regions. In an intracranial GBM patient-derived xenograft model, AZD1390 accumulation was higher in the tumor core and rim compared with surrounding brain. Despite this heterogenous delivery within tumor-bearing brain, AZD1390 concentrations in normal brain, tumor rim, and tumor core were above in vitro effective radiosensitizing concentrations. These results indicate that despite being a substrate of efflux in the mouse brain, sufficient AZD1390 exposure is anticipated even in regions of normal brain. SIGNIFICANCE STATEMENT: Given the invasive nature of glioblastoma (GBM), tumor cells are often protected by an intact blood-brain barrier, requiring the development of brain-penetrant molecules for effective treatment. We show that efflux mediated by P-glycoprotein (P-gp) limits central nervous system (CNS) distribution of AZD1390 and that there are no distributional differences within anatomical regions of CNS. Despite efflux by P-gp, concentrations effective for potent radiosensitization are achieved in GBM tumor-bearing mouse brains, indicating that AZD1390 is an attractive molecule for clinical development of brain tumors.
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Affiliation(s)
- Surabhi Talele
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., W.F.E.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.C., S.K.G., D.M.B., J.N.S.)
| | - Wenjuan Zhang
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., W.F.E.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.C., S.K.G., D.M.B., J.N.S.)
| | - Jiajia Chen
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., W.F.E.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.C., S.K.G., D.M.B., J.N.S.)
| | - Shiv K Gupta
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., W.F.E.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.C., S.K.G., D.M.B., J.N.S.)
| | - Danielle M Burgenske
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., W.F.E.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.C., S.K.G., D.M.B., J.N.S.)
| | - Jann N Sarkaria
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., W.F.E.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.C., S.K.G., D.M.B., J.N.S.)
| | - William F Elmquist
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., W.F.E.); Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (J.C., S.K.G., D.M.B., J.N.S.)
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Talele S, Zhang W, Oh JH, Burgenske DM, Mladek AC, Dragojevic S, Sarkaria JN, Elmquist WF. Central Nervous System Delivery of the Catalytic Subunit of DNA-Dependent Protein Kinase Inhibitor Peposertib as Radiosensitizer for Brain Metastases. J Pharmacol Exp Ther 2022; 381:217-228. [PMID: 35370138 PMCID: PMC9190234 DOI: 10.1124/jpet.121.001069] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 03/21/2022] [Indexed: 07/22/2023] Open
Abstract
Cytotoxic effects of chemotherapy and radiation therapy (RT) used for the treatment of brain metastases results from DNA damage within cancer cells. Cells rely on highly evolved DNA damage response (DDR) pathways to repair the damage caused by these treatments. Inhibiting these repair pathways can further sensitize cancer cells to chemotherapy and RT. The catalytic subunit of DNA-dependent protein kinase, in a complex with Ku80 and Ku70, is a pivotal regulator of the DDR, and peposertib is a potent inhibitor of this catalytic subunit. The characterization of central nervous system (CNS) distributional kinetics of peposertib is critical in establishing a therapeutic index in the setting of brain metastases. Our studies demonstrate that the delivery of peposertib is severely restricted into the CNS as opposed to peripheral organs, by active efflux at the blood-brain barrier (BBB). Peposertib has a low free fraction in the brain and spinal cord, further reducing the active concentration, and distributes to the same degree within different anatomic regions of the brain. However, peposertib is heterogeneously distributed within the metastatic tumor, where its concentration is highest within the tumor core (with disrupted BBB) and substantially lower within the invasive tumor rim (with a relatively intact BBB) and surrounding normal brain. These findings are critical in guiding the potential clinical deployment of peposertib as a radiosensitizing agent for the safe and effective treatment of brain metastases. SIGNIFICANCE STATEMENT: Effective radiosensitization of brain metastases while avoiding toxicity to the surrounding brain is critical in the development of novel radiosensitizers. The central nervous system distribution of peposertib, a potent catalytic subunit of DNA-dependent protein kinase inhibitor, is restricted by active efflux in the normal blood-brain barrier (BBB) but can reach significant concentrations in the tumor core. This finding suggests that peposertib may be an effective radiosensitizer for intracranial tumors with an open BBB, while limited distribution into normal brain will decrease the risk of enhanced radiation injury.
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Affiliation(s)
- Surabhi Talele
- Department of Pharmaceutics, Brain Barriers Research Center, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., J.-H.O., W.F.E.) and Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (D.M.B., A.C.M., S.D., J.N.S.)
| | - Wenjuan Zhang
- Department of Pharmaceutics, Brain Barriers Research Center, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., J.-H.O., W.F.E.) and Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (D.M.B., A.C.M., S.D., J.N.S.)
| | - Ju-Hee Oh
- Department of Pharmaceutics, Brain Barriers Research Center, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., J.-H.O., W.F.E.) and Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (D.M.B., A.C.M., S.D., J.N.S.)
| | - Danielle M Burgenske
- Department of Pharmaceutics, Brain Barriers Research Center, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., J.-H.O., W.F.E.) and Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (D.M.B., A.C.M., S.D., J.N.S.)
| | - Ann C Mladek
- Department of Pharmaceutics, Brain Barriers Research Center, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., J.-H.O., W.F.E.) and Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (D.M.B., A.C.M., S.D., J.N.S.)
| | - Sonja Dragojevic
- Department of Pharmaceutics, Brain Barriers Research Center, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., J.-H.O., W.F.E.) and Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (D.M.B., A.C.M., S.D., J.N.S.)
| | - Jann N Sarkaria
- Department of Pharmaceutics, Brain Barriers Research Center, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., J.-H.O., W.F.E.) and Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (D.M.B., A.C.M., S.D., J.N.S.)
| | - William F Elmquist
- Department of Pharmaceutics, Brain Barriers Research Center, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota (S.T., W.Z., J.-H.O., W.F.E.) and Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (D.M.B., A.C.M., S.D., J.N.S.)
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Abstract
Glioblastoma (GBM) is a highly invasive primary brain tumor in adults with a 5-year survival rate of less than 10%. Conventional radiotherapy with photons, along with concurrent and adjuvant temozolomide, is the mainstay for treatment of GBM although no significant improvement in survival rates has been observed over the last 20 years. Inherent factors such as tumor hypoxia, radioresistant GBM stem cells, and upregulated DNA damage response mechanisms are well established as contributing to treatment resistance and tumor recurrence. While it is understandable that efforts have focused on targeting these factors to overcome this phenotype, there have also been striking advances in precision radiotherapy techniques, including proton beam therapy and carbon ion radiotherapy (CIRT). These enable higher doses of radiation to be delivered precisely to the tumor, while minimizing doses to surrounding normal tissues and organs at risk. These alternative radiotherapy techniques also benefit from increased biological effectiveness, particularly in the case of CIRT. Although not researched extensively to date, combining these new radiation modalities with radio-enhancing agents may be particularly effective in improving outcomes for patients with GBM.
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Affiliation(s)
- Radhika Aiyappa-Maudsley
- Department of Molecular and Clinical Cancer Medicine, University of Liverpool, William Henry Duncan Building, Liverpool, L7 8TX, UK
| | - Anthony J Chalmers
- Institute of Cancer Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Jason L Parsons
- Department of Molecular and Clinical Cancer Medicine, University of Liverpool, William Henry Duncan Building, Liverpool, L7 8TX, UK
- Clatterbridge Cancer Centre NHS Foundation Trust, Clatterbridge Road, Bebington, CH63 4JY, UK
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