Developing modulators of tumour hypoxia through inhibition of cellular oxygen consumption
Nicole Machado,
United Kingdom
OC-0098
Abstract
Developing modulators of tumour hypoxia through inhibition of cellular oxygen consumption
Authors: Nicole Machado1, James Holt-Martyn2, Gonzalo Rodriguez-Berriguete1, Elysia Traynor1, Rathi Puliyadi3, Christopher Schofield2, Geoff Higgins1
1University of Oxford , Department of Oncology, Oxford, United Kingdom; 2University of Oxford , Department of Chemistry, Oxford, United Kingdom; 3University of Oxford , Department of Oncology , Oxford, United Kingdom
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Purpose or Objective
Tumor hypoxia is strongly associated with poor clinical outcomes and radiation therapy resistance (1). Previous studies have demonstrated that reducing the oxygen consumption rate (OCR) of tumour cells can be an effective strategy in increasing local oxygen availability to overcome hypoxia (2-4). Recent screening work by the Higgins lab has identified a prodrug, referred to as compound A, to strongly reduce OCR in vitro (4). However, compound A is completely metabolized in vivo to compound B, which has no effect on OCR (4). In the present work, derivatives of compound A that evade metabolism but maintain OCR inhibition have been assessed for their efficacy as tumour hypoxia modulators.
Material and Methods
OCR in Fadu and HCT116 cells is measured after 24 hour treatments with compound A derivatives 719 and 1059, compound A, compound B at 30µM, 10µM, and 5µM. Hypoxia is assessed in HCT116 spheroids using EF5 and quantified by immunofluorescent staining after 24 hour incubation with 719, 1059, compound A, and compound B at 10µM and 2µM. 719 and 1059 are administered via oral gavage in HCT116 nude mice xenografts to assess tumour hypoxia alleviation via EF5 staining. 719 is delivered once daily at 15 mg/kg for 8 days (n=4-5) and 1059 is delivered twice daily at 60 mg/kg for 7 days (n=7-8). OCR in HCT116 cells is measured after 24-hour treatments with a new, more soluble series of compound A derivatives.
Results
719 and 1059 significantly reduce OCR in both cell lines and alleviate hypoxia in spheroids, outperforming compound A at 10 µM or lower. Oral delivery of 719 and 1059, at dosing schedules determined by toxicity and drug solubility limits, do not reduce hypoxia in vivo. 17 out of the 24 new compound A derivatives, optimized for improved solubility, produce a more than 50% reduction in OCR in HCT116 cells.
Conclusion
Compound A derivatives 719 and 1059 are potent inhibitors of OCR and alleviate hypoxia in 3D spheroids in vitro. Oral delivery of 719 and 1059 is ineffective in reducing hypoxia in vivo. Further screening in 2D and 3D in vitro models of a pharmacokinetically favorable series of compound A derivatives will guide the selection of a suitable in vivo candidate molecule for tumour hypoxia modification. This work will identify potential hypoxia modifiers to help improve radiotherapy efficacy in clinic.
References
(1) Wilson WR, et al. Nat Rev Cancer. 2011 Jun;11(6):393-410.
(2) Jordan BF, et al. Front Pharmacol. 2012 May;3:94.
(3) Zannella VE, et al. Clin Cancer Res. 2013 Dec 15;19(24):6741-50.
(4) Ashton TM, et al. Nat Commun. 2016 Jul 25;7:12308.