Abstract A110: Hypoxia-selective DNA-PK inhibitor

• Published in: Molecular cancer therapeutics Vol. 17; no. 1_Supplement; p. A110
• Main Authors: Kyle, Alastair H., Baker, Jennifer H.E., Fryer, Karen H., Banaáth, Judit, Wang, Taixiang, Porres, Soraya S., Mann, Sam E., Hynd, George, Menear, Keith, Minchinton, Andrew I.
• Format: Journal Article
• Language: English
• Published: 01.01.2018
• ISSN: 1535-7163; 1538-8514
• DOI: 10.1158/1535-7163.TARG-17-A110

Abstract Targeting tumor hypoxia continues to be a goal of translational radiation oncology owing to overwhelming preclinical and clinical validation of the importance of tumor oxygenation to radiation sensitivity. We describe a rational, structure-based drug development and characterization program for novel prodrugs that can target DNA-PK selectively within hypoxic tumor cells. The dual selectivity of these prodrugs has the potential to substantially improve the therapeutic index of radiation therapy used to treat numerous cancers. Using several biochemical, cell and novel tissue-based screening systems we explored the mechanistic and biologic activity of two new classes of DNA-PK inhibitors. Iterative improvements in molecular activity were driven by high-throughput assays utilizing both immunostaining and clonogenic survival endpoints. Kinase selectivity and in vitro ADME assays facilitated the identification of drug-like compounds with the potential for good oral bioavailability. 3D-tissue culture models helped explore tissue penetration and bystander effects and experiments analyzing the oxygen dependence of prodrug cleavage to the active DNA-PK inhibitors guided the selection of hypoxic trigger moieties. Novel parental compounds and hypoxia-activated prodrugs in two distinct chemical classes that are potent inhibitors of DNA-PK have been developed. Lead compounds exhibit high in vitro potency and good oral drug-like properties and show significant enhancement of radiation-induced cytotoxicity. In vivo experiments indicate excellent oral bioavailability with plasma T½‘s exceeding 30 minutes and significant antitumor activity against human xenografts. Citation Format: Alastair H. Kyle, Jennifer H.E. Baker, Karen H. Fryer, Judit Bana áth, Taixiang Wang, Soraya S. Porres, Sam E. Mann, George Hynd, Keith Menear, Andrew I. Minchinton. Hypoxia-selective DNA-PK inhibitor [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A110.