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ATR inhibition induces synthetic lethality and overcomes chemoresistance in TP53- or ATM-defective chronic lymphocytic leukemia cells.

Kwok, Marwan and Davies, Nicholas and Agathanggelou, Angelo and Smith, Edward and Oldreive, Ceri and Petermann, Eva and Stewart, Grant and Brown, Jeff and Lau, Alan and Pratt, Guy and Parry, Helen and Taylor, Malcolm and Moss, Paul and Hillmen, Peter and Stankovic, Tatjana (2016) ATR inhibition induces synthetic lethality and overcomes chemoresistance in TP53- or ATM-defective chronic lymphocytic leukemia cells. Blood, 127 (5). pp. 582-95. ISSN 1528-0020. This article is available to all HEFT staff and students via http://tinyurl.com/z795c8c by using their HEFT Athens login IDs

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Official URL: http://www.bloodjournal.org/content/127/5/582.long...

Abstract

TP53 and ataxia telangiectasia mutated (ATM) defects are associated with genomic instability, clonal evolution, and chemoresistance in chronic lymphocytic leukemia (CLL). Currently, therapies capable of providing durable remissions in relapsed/refractory TP53- or ATM-defective CLL are lacking. Ataxia telangiectasia and Rad3-related (ATR) mediates response to replication stress, the absence of which leads to collapse of stalled replication forks into chromatid fragments that require resolution through the ATM/p53 pathway. Here, using AZD6738, a novel ATR kinase inhibitor, we investigated ATR inhibition as a synthetically lethal strategy to target CLL cells with TP53 or ATM defects. Irrespective of TP53 or ATM status, induction of CLL cell proliferation upregulated ATR protein, which then became activated in response to replication stress. In TP53- or ATM-defective CLL cells, inhibition of ATR signaling by AZD6738 led to an accumulation of unrepaired DNA damage, which was carried through into mitosis because of defective cell cycle checkpoints, resulting in cell death by mitotic catastrophe. Consequently, AZD6738 was selectively cytotoxic to both TP53- and ATM-defective CLL cell lines and primary cells. This was confirmed in vivo using primary xenograft models of TP53- or ATM-defective CLL, where treatment with AZD6738 resulted in decreased tumor load and reduction in the proportion of CLL cells with such defects. Moreover, AZD6738 sensitized TP53- or ATM-defective primary CLL cells to chemotherapy and ibrutinib. Our findings suggest that ATR is a promising therapeutic target for TP53- or ATM-defective CLL that warrants clinical investigation.

Item Type: Article
Additional Information: This article is available to all HEFT staff and students via http://tinyurl.com/z795c8c by using their HEFT Athens login IDs
Subjects: WH Haemic and lymphatic systems. Haematology
Divisions: Planned IP Care > Oncology and Clinical Haematology
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Depositing User: Mrs Caroline Tranter
Date Deposited: 10 Feb 2017 10:19
Last Modified: 10 Feb 2017 10:19
URI: http://www.repository.heartofengland.nhs.uk/id/eprint/1186

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