Improved pharmacodynamic (PD) assessment of low dose PARP inhibitor PD activity for radiotherapy and chemotherapy combination trials
Publication year
2018Source
Radiotherapy and Oncology, 126, 3, (2018), pp. 443-449ISSN
Publication type
Article / Letter to editor

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Organization
Pulmonary Diseases
Radiation Oncology
Journal title
Radiotherapy and Oncology
Volume
vol. 126
Issue
iss. 3
Page start
p. 443
Page end
p. 449
Subject
Radboudumc 9: Rare cancers RIHS: Radboud Institute for Health Sciences; Radboudumc 9: Rare cancers RIMLS: Radboud Institute for Molecular Life SciencesAbstract
BACKGROUND: PARP inhibitors are currently evaluated in combination with radiotherapy and/or chemotherapy. As sensitizers, PARP inhibitors are active at very low concentrations therefore requiring highly sensitive pharmacodynamic (PD) assays. Current clinical PD-assays partly fail to provide such sensitivities. The aim of our study was to enable sensitive PD evaluation of PARP inhibitors for clinical sensitizer development. MATERIAL AND METHODS: PBMCs of healthy individuals and of olaparib and radiotherapy treated lung cancer patients were collected for ELISA-based PD-assays. RESULTS: PAR-signal amplification by ex vivo irradiation enabled an extended quantification range for PARP inhibitory activities after ex vivo treatment with inhibitors. This "radiation-enhanced-PAR" (REP) assay provided accurate IC50 values thereby also revealing differences among healthy individuals. Implemented in clinical radiotherapy combination Phase I trials, the REP-assay showed sensitive detection of PARP inhibition in patients treated with olaparib and establishes strong PARP inhibitory activities at low daily doses. CONCLUSIONS: Combination trials of radiotherapy and novel targeted agent(s) often require different and more sensitive PD assessments than in the monotherapy setting. This study shows the benefit and relevance of sensitive and adapted PD-assays for such combination purposes and provides proof of clinically relevant cellular PARP inhibitory activities at low daily olaparib doses.
This item appears in the following Collection(s)
- Academic publications [234108]
- Faculty of Medical Sciences [89175]
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