2. Academic Validation
  3. Polθ inhibitors elicit BRCA-gene synthetic lethality and target PARP inhibitor resistance

Polθ inhibitors elicit BRCA-gene synthetic lethality and target PARP inhibitor resistance

  • Nat Commun. 2021 Jun 17;12(1):3636. doi: 10.1038/s41467-021-23463-8.
Diana Zatreanu  # 1 2,  Helen M R Robinson  # 3,  Omar Alkhatib 3,  Marie Boursier 3,  Harry Finch 3,  Lerin Geo 3,  Diego Grande 3,  Vera Grinkevich 3,  Robert A Heald 3,  Sophie Langdon 3,  Jayesh Majithiya 3,  Claire McWhirter 3,  Niall M B Martin 3,  Shaun Moore 3,  Joana Neves 3,  Eeson Rajendra 3,  Marco Ranzani 3,  Theresia Schaedler 3,  Martin Stockley 3,  Kimberley Wiggins 3,  Rachel Brough 1 2,  Sandhya Sridhar 1 2,  Aditi Gulati 1 2,  Nan Shao 1 2,  Luned M Badder 4,  Daniela Novo 2,  Eleanor G Knight 2,  Rebecca Marlow 2 4,  Syed Haider 2,  Elsa Callen 5,  Graeme Hewitt 6,  Joost Schimmel 7,  Remko Prevo 8,  Christina Alli 9,  Amanda Ferdinand 9,  Cameron Bell 9,  Peter Blencowe 9,  Chris Bot 9,  Mathew Calder 9,  Mark Charles 9,  Jayne Curry 9,  Tennyson Ekwuru 9,  Katherine Ewings 9,  Wojciech Krajewski 9,  Ellen MacDonald 9,  Hollie McCarron 9,  Leon Pang 9,  Chris Pedder 9,  Laurent Rigoreau 9,  Martin Swarbrick 9,  Ed Wheatley 9,  Simon Willis 9,  Ai Ching Wong 9,  Andre Nussenzweig 5,  Marcel Tijsterman 7,  Andrew Tutt 2 4,  Simon J Boulton 3 6,  Geoff S Higgins 8,  Stephen J Pettitt 10 11,  Graeme C M Smith 12,  Christopher J Lord 13 14
Affiliations

Affiliations

  • 1 CRUK Gene Function Laboratory, The Institute of Cancer Research, London, UK.
  • 2 The Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London, UK.
  • 3 Artios Pharma, The Glenn Berge Building, Babraham Research Campus, Cambridge, UK.
  • 4 The Breast Cancer Now Research Unit, King's College London, London, UK.
  • 5 Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA.
  • 6 The Francis Crick Institute, London, UK.
  • 7 Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
  • 8 Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford, UK.
  • 9 Cancer Research UK, Therapeutic Discovery Laboratories, Jonas Webb Building, Babraham Research Campus, Cambridge, UK.
  • 10 CRUK Gene Function Laboratory, The Institute of Cancer Research, London, UK. [email protected].
  • 11 The Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London, UK. [email protected].
  • 12 Artios Pharma, The Glenn Berge Building, Babraham Research Campus, Cambridge, UK. [email protected].
  • 13 CRUK Gene Function Laboratory, The Institute of Cancer Research, London, UK. [email protected].
  • 14 The Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London, UK. [email protected].
  • # Contributed equally.
PMID: 34140467 DOI: 10.1038/s41467-021-23463-8
Abstract

To identify approaches to target DNA repair vulnerabilities in Cancer, we discovered nanomolar potent, selective, low molecular weight (MW), allosteric inhibitors of the polymerase function of DNA polymerase Polθ, including ART558. ART558 inhibits the major Polθ-mediated DNA repair process, Theta-Mediated End Joining, without targeting Non-Homologous End Joining. In addition, ART558 elicits DNA damage and synthetic lethality in BRCA1- or BRCA2-mutant tumour cells and enhances the effects of a PARP Inhibitor. Genetic perturbation screening revealed that defects in the 53BP1/Shieldin complex, which cause PARP Inhibitor resistance, result in in vitro and in vivo sensitivity to small molecule Polθ polymerase inhibitors. Mechanistically, ART558 increases biomarkers of single-stranded DNA and synthetic lethality in 53BP1-defective cells whilst the inhibition of DNA nucleases that promote end-resection reversed these effects, implicating these in the synthetic lethal mechanism-of-action. Taken together, these observations describe a drug class that elicits BRCA-gene synthetic lethality and PARP Inhibitor synergy, as well as targeting a biomarker-defined mechanism of PARPi-resistance.

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