Enhancement of the therapeutic effects of fractionated and low dose rate radiotherapy by inhibition of PARP-1.

Lead Research Organisation: University of Sussex
Department Name: Brighton and Sussex Medical School

Abstract

Successful anti-cancer therapies exploit the differences that exist between malignant and healthy cells. However, many current treatments are limited by the damage they inflict upon the normal tissues of the body. In the case of the malignant brain tumour known as glioblastoma multiforme (GBM), the tumour cells are rapidly dividing whereas the surrounding normal brain cells are non-dividing. We have found that blocking the activity of a protein known as PARP-1 makes cells more sensitive to radiotherapy treatment, but only if they are actively dividing. Combining radiotherapy treatment with a drug that inhibited PARP-1 activity would increase the ability of the radiation to kill the rapidly dividing cancer cells without causing additional damage to surrounding healthy cells, and may therefore increase cure rates. The aim of our project is to verify that the PARP inhibitors increase the sensitivity of tumour cells derived from GBM specimens without affecting normal brain cells, and to determine the radiotherapy schedule that gives the best results. The project will also investigate the interactions that take place between PARP-1 and other molecules involved in the response to radiotherapy, with a view to identifying combinations of drug treatments that will maximise the anti-cancer effects of radiotherapy.

Technical Summary

Aim: To enhance the effectiveness of conventional radiotherapy regimes by inhibiting the function of the nuclear protein poly(ADP-ribose) polymerase-1 (PARP-1).
Background: PARP-1 is rapidly activated by single and double strand breaks in DNA, and contributes to resolution of these lesions by modulating multiple DNA repair pathways. The observation that PARP-1 inhibitors sensitise actively dividing but not growth-arrested human tumour cells to ionising radiation suggests that PARP-1 inhibition might enhance the therapeutic ratio of conventional radiotherapy regimes. Pronounced sensitisation of certain cell lines to very low doses of radiation, and evidence that PARP-1 inhibition reduces the rate of DNA strand break repair, indicates that PARP-1 inhibition and continuous low dose rate radiotherapy might a particularly effective combination.
Objectives:
1. To ascertain the extent to which PARP-1 inhibition enhances sensitivity of human tumour cells to fractionated and continuous low dose rate radiation, and to identify the common features of those cell lines in which radiosensitisation is most marked.
2. To elucidate the mechanisms underlying the radiosensitising effects of PARP-1 inhibition.
Methods:
1. The effect of inhibition of PARP-1 on radiosensitivity of a variety of human tumour cell lines will be measured using an established clonogenic survival assay. Highly potent and specific PARP-1 inhibitors will be used in collaboration with KuDOS Pharmaceuticals. Cells will be exposed to three radiation regimes: a range of single acute doses (0.05-5 Gy); a series of daily 2 Gy fractions; and continuous low dose rate radiation (in collaboration with the Gray Cancer Institute). Cell line characteristics that correlate with the magnitude of the radiosensitising effect of PARP-1 inhibition will be identified.
2. The interactions that determine radiation sensitivity will be investigated by measuring the effect of PARP-1 inhibition on clonogenic survival in cell lines lacking specific DNA repair proteins. Cells deficient in ATM, XRCC1, DNA-PKcs and BRCA1 are available at the host institute; PARP-1 and PARP-2 knockout cell lines will be provided by Gilbert de Murcia. Relevant associations will be characterised by biochemical analysis of protein-protein interactions in vitro. Comet assays and assessment of H2AX foci will enable quantitative analysis of the effect of PARP-1 status on resolution of DNA single and double strand breaks. The relative contributions of PARP-1 and PARP-2 to radiation sensitivity will be elucidated by measuring survival, DNA repair and protein interactions in PARP-1 and PARP-2 knockout cell lines.

Publications

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Chalmers AJ (2009) Cytotoxic effects of temozolomide and radiation are additive- and schedule-dependent. in International journal of radiation oncology, biology, physics

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Yu SK (2007) Patients receiving standard-dose temozolomide therapy are at risk of Pneumocystis carinii pneumonia. in Clinical oncology (Royal College of Radiologists (Great Britain))

 
Description Cancer Research UK Strategic Review of Radiation Biology and Radiation Oncology
Geographic Reach National 
Policy Influence Type Participation in a advisory committee
 
Description ICR MSc Oncology Module Leader
Geographic Reach National 
Policy Influence Type Influenced training of practitioners or researchers
Impact Increase in academic clinical oncology personnel in the UK. Increase in radiotherapy clinical trials.
 
Description MRC Senior Clinical Fellowship
Amount £1,400,000 (GBP)
Organisation Medical Research Council (MRC) 
Sector Public
Country United Kingdom
Start 08/2009 
End 07/2014
 
Description Clinical trial of olaparib in recurrent glioblastoma 
Organisation AstraZeneca
Country United Kingdom 
Sector Private 
PI Contribution I am Chief Investigator and have written the protocol.
Collaborator Contribution Approved funding for a phase I clinical trial. The Drug Development Office of CRUK are managing the study, for which I am Chief Investigator. Astra Zeneca has provided drug and performed some assays.
Impact Phase I clinical trial.
Start Year 2009
 
Description Clinical trial of olaparib in recurrent glioblastoma 
Organisation Cancer Research UK
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution I am Chief Investigator and have written the protocol.
Collaborator Contribution Approved funding for a phase I clinical trial. The Drug Development Office of CRUK are managing the study, for which I am Chief Investigator. Astra Zeneca has provided drug and performed some assays.
Impact Phase I clinical trial.
Start Year 2009
 
Description Local therapy for glioblastoma multiforme 
Organisation BTG
Department Biocompatibles
Country United Kingdom 
Sector Private 
PI Contribution Conducted experiments, intellectual discussion.
Collaborator Contribution Provided reagents and intellectual discussion.
Impact Clinical trial protocol developed - not funded.
Start Year 2008
 
Description Radiation and temozolomide interactions 
Organisation University College London
Department UCL Cancer Institute
Country United Kingdom 
Sector Academic/University 
PI Contribution Generated data, co-authors on publication.
Collaborator Contribution Generated additional data, co-author on paper.
Impact Publication: Cytotoxic effects of temozolomide and radiation are additive- and schedule-dependent. Chalmers AJ, Ruff EM, Martindale C, Lovegrove N, Short SC. Int J Radiat Oncol Biol Phys. 2009 Dec 1;75(5):1511-9.
Start Year 2008
 
Description UK glioblastoma radiotherapy-drug combinations consortium 
Organisation CTRad
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution Based on my previous scientific and clinical research in this field I initiated and am organising and hosting a workshop aimed at developing a multi-centre, multi-arm, multi-stage clinical trial of radiotherapy in combination with various DNA repair inhibitors in the treatment of glioblastoma. The consortium will include clinicians, biological and imaging scientists, pharmaceutical companies, statisticians and consumer representatives.
Collaborator Contribution CTRad supporting workshop expenses and travel for invited speakers. NCRI Brain Tumour CSG supporting workshop administration. Clinical Trials Unit Glasgow supporting workshop administration and future development of the clinical trial.
Impact Workshop taking place in Glasgow on 16-17 March 2017
Start Year 2016
 
Description UK glioblastoma radiotherapy-drug combinations consortium 
Organisation Cancer Research UK
Department Clinical Trials Unit (CTU) Glasgow
Country United Kingdom 
Sector Academic/University 
PI Contribution Based on my previous scientific and clinical research in this field I initiated and am organising and hosting a workshop aimed at developing a multi-centre, multi-arm, multi-stage clinical trial of radiotherapy in combination with various DNA repair inhibitors in the treatment of glioblastoma. The consortium will include clinicians, biological and imaging scientists, pharmaceutical companies, statisticians and consumer representatives.
Collaborator Contribution CTRad supporting workshop expenses and travel for invited speakers. NCRI Brain Tumour CSG supporting workshop administration. Clinical Trials Unit Glasgow supporting workshop administration and future development of the clinical trial.
Impact Workshop taking place in Glasgow on 16-17 March 2017
Start Year 2016
 
Description UK glioblastoma radiotherapy-drug combinations consortium 
Organisation National Cancer Research Institute (NCRI)
Department NCRI Brain Tumour CSG
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution Based on my previous scientific and clinical research in this field I initiated and am organising and hosting a workshop aimed at developing a multi-centre, multi-arm, multi-stage clinical trial of radiotherapy in combination with various DNA repair inhibitors in the treatment of glioblastoma. The consortium will include clinicians, biological and imaging scientists, pharmaceutical companies, statisticians and consumer representatives.
Collaborator Contribution CTRad supporting workshop expenses and travel for invited speakers. NCRI Brain Tumour CSG supporting workshop administration. Clinical Trials Unit Glasgow supporting workshop administration and future development of the clinical trial.
Impact Workshop taking place in Glasgow on 16-17 March 2017
Start Year 2016
 
Description Brain Tumour Support Group 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Participants in your research and patient groups
Results and Impact Informal presentation on my research and on clinical trials for patients with brain tumours.

None.
Year(s) Of Engagement Activity 2007,2009