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U87/Centrin2-EGFP/H2B-mCherry/puro cells were seeded on dishes with cover slip bottoms, treated with AZ32 (3 uM), and irradiated (5 Gy). Time-lapse videos were recorded intermittently (every 7 min) over 16 hrs. Treatment results in 11% aberrant mitoses (see Fig. 3F).

U87/shp53/Centrin2-EGFP/H2B-mCherry/shp53 cells were seeded on dishes with cover slip bottoms and irradiated (5 Gy). Time-lapse videos were recorded intermittently (every 7 min) over 16 hrs. Treatment results in 12% aberrant mitoses (see Fig. 3F).

U87/Centrin2-EGFP/H2B-mCherry/puro cells were seeded on dishes with cover slip bottoms and irradiated (5 Gy). Time-lapse videos were recorded intermittently (every 7 min) over 16 hrs. Treatment results in 2.7% aberrant mitoses (see Fig. 3F).

Inhibition of ataxia-telangiectasia mutated (ATM) during radiotherapy of glioblastoma multiforme (GBM) may improve tumor control by short-circuiting the response to radiation-induced DNA damage. A major impediment for clinical implementation is that current inhibitors have limited central nervous system (CNS) bioavailability; thus, the goal was to identify ATM inhibitors (ATMi) with improved CNS penetration. Drug screens and refinement of lead compounds identified AZ31 and AZ32. The compounds were then tested in vivo for efficacy and impact on tumor and healthy brain. Both AZ31 and AZ32 blocked the DNA damage response and radiosensitized GBM cells in vitro. AZ32, with enhanced blood–brain barrier (BBB) penetration, was highly efficient in vivo as radiosensitizer in syngeneic and human, orthotopic mouse glioma model compared with AZ31. Furthermore, human glioma cell lines expressing mutant p53 or having checkpoint-defective mutations were particularly sensitive to ATMi radiosensitization. The mechanism for this p53 effect involves a propensity to undergo mitotic catastrophe relative to cells with wild-type p53. In vivo, apoptosis was >6-fold higher in tumor relative to healthy brain after exposure to AZ32 and low-dose radiation. AZ32 is the first ATMi with oral bioavailability shown to radiosensitize glioma and improve survival in orthotopic mouse models. These findings support the development of a clinical-grade, BBB-penetrating ATMi for the treatment of GBM. Importantly, because many GBMs have defective p53 signaling, the use of an ATMi concurrent with standard radiotherapy is expected to be cancer-specific, increase the therapeutic ratio, and maintain full therapeutic effect at lower radiation doses. Mol Cancer Ther; 17(8); 1637–47. ©2018 AACR.

Background AZD0156 and AZD6738 are potent and selective inhibitors of ataxia-telangiectasia-kinase (ATM) and ataxia-telangiectasia-mutated and Rad3-related (ATR), respectively, important sensors/signallers of DNA damage. Methods We used multiplexed targeted-mass-spectrometry to select pRAD50(Ser635) as a pharmacodynamic biomarker for AZD0156-mediated ATM inhibition from a panel of 45 peptides, then developed and tested a clinically applicable immunohistochemistry assay for pRAD50(Ser635) detection in FFPE tissue. Results We found moderate pRAD50 baseline levels across cancer indications. pRAD50 was detectable in 100% gastric cancers (n = 23), 99% colorectal cancers (n = 102), 95% triple-negative-breast cancers (TNBC) (n = 40) and 87.5% glioblastoma-multiformes (n = 16). We demonstrated AZD0156 target inhibition in TNBC patient-derived xenograft models; where AZD0156 monotherapy or post olaparib treatment, resulted in a 34–72% reduction in pRAD50. Similar inhibition of pRAD50 (68%) was observed following ATM inhibitor treatment post irinotecan in a colorectal cancer xenograft model. ATR inhibition, using AZD6738, increased pRAD50 in the ATM-proficient models whilst in ATM-deficient models the opposite was observed, suggesting pRAD50 pharmacodynamics post ATR inhibition may be ATM-dependent and could be useful to determine ATM functionality in patients treated with ATR inhibitors. Conclusion Together these data support clinical utilisation of pRAD50 as a biomarker of AZD0156 and AZD6738 pharmacology to elucidate clinical pharmacokinetic/pharmacodynamic relationships, thereby informing recommended Phase 2 dose/schedule.

Inhibition of ataxia-telangiectasia mutated (ATM) during radiotherapy of glioblastoma multiforme (GBM) may improve tumor control by short-circuiting the response to radiation-induced DNA damage. A major impediment for clinical implementation is that current inhibitors have limited central nervous system (CNS) bioavailability; thus, the goal was to identify ATM inhibitors (ATMi) with improved CNS penetration. Drug screens and refinement of lead compounds identified AZ31 and AZ32. The compounds were then tested in vivo for efficacy and impact on tumor and healthy brain. Both AZ31 and AZ32 blocked the DNA damage response and radiosensitized GBM cells in vitro. AZ32, with enhanced blood–brain barrier (BBB) penetration, was highly efficient in vivo as radiosensitizer in syngeneic and human, orthotopic mouse glioma model compared with AZ31. Furthermore, human glioma cell lines expressing mutant p53 or having checkpoint-defective mutations were particularly sensitive to ATMi radiosensitization. The mechanism for this p53 effect involves a propensity to undergo mitotic catastrophe relative to cells with wild-type p53. In vivo, apoptosis was >6-fold higher in tumor relative to healthy brain after exposure to AZ32 and low-dose radiation. AZ32 is the first ATMi with oral bioavailability shown to radiosensitize glioma and improve survival in orthotopic mouse models. These findings support the development of a clinical-grade, BBB-penetrating ATMi for the treatment of GBM. Importantly, because many GBMs have defective p53 signaling, the use of an ATMi concurrent with standard radiotherapy is expected to be cancer-specific, increase the therapeutic ratio, and maintain full therapeutic effect at lower radiation doses. Mol Cancer Ther; 17(8); 1637–47. ©2018 AACR.

ATM plays a central role in the detection, signalling, and repair of DNA double-strand breaks (DSB), the most cytotoxic lesion induced by ionizing radiation (IR) and certain chemotherapies. ATM is also activated by reactive oxygen species (ROS) induced by cellular exposures to IR. Genetic ablation and pharmacologic inhibition of ATM is associated with extreme hypersensitivity of glioblastoma multiforme (GBM) tumor cells to IR, especially those with checkpoint defects such as p53 abrogations. GBM is the most common and lethal form of brain tumor. Median survival of patients is 12-15 months, despite surgery, fractionated radiotherapy, and temozolomide standard of care. Poor survival is attributed to an inability to excise all tumor tissue (if operable), dissemination of disease into regions with an intact blood-brain barrier (BBB), and an intrinsic radio- and chemo-resistance. With ATM activity robustly upregulated in GBM stem cells, ATM represents an attractive radiosensitization target. Here, we describe the activity of AZD1390, a potent, selective, and orally bioavailable ATM inhibitor optimized for BBB penetration in preclinical model species. AZD1390 demonstrates exquisitely potent cellular inhibition of ATM activity (IC50 0.78 nM) with >1000-fold activity over closely related (PIKKs) and distant kinases. We confirm target and pathway engagement by Western blot and imaging pan-nuclear and discreet pATM foci staining (IC50 0.6-3nM). Radiosensitization of a panel of GBM cell lines and NCI-H2228 lung cells was confirmed in antiproliferation and clonogenic assays (IC50 3 nM). DEF37 of 2.7 was seen in p53 mutant GBM cells dosed at 3nM and p53 mutant GBM cell lines were more radiosensitized than wild type cells. Radiosensitization was confirmed in vivo in mouse orthotopic NCI-H2228 lung tumor models implanted directly into brain or via carotid artery injection showing dose-dependent tumor growth inhibition and remarkable increases in survival of mice when dosing AZD1390 PO an hour before four daily fractions of 2.5 Gy IR to the whole head. 20 mg/kg QD or BID gave the best survival benefit that correlated with bioluminescent tumor growth inhibition. Doses lower than 2 mg/kg were not efficacious, suggesting free brain PK cover over ATM IC50 of 3 hours or more are required for efficacy. Efficacy was also achieved in a dose-dependent manner in orthotopic GL261 murine GBM syngeneic models dosed in combination with either whole head radiotherapy or stereotactic beam radiotherapy. A PK PD efficacy relationship was establish by correlating AZD1390 free brain PK levels, phospho-ATM/Rad50 detection in tumor by IHC, and tumor growth inhibition and survival. Significant brain exposure was observed in a nonhuman primate PET study utilizing 11C-labelled AZD1390, further supporting the ability of the compound to efficiently cross the BBB. With confirmation that AZD1390 is not a substrate for human efflux transporters and having favorable pharmacokinetic and pharmacodynamic properties, AZD1390 is now in early clinical development for use as a radiosensitizer in central nervous system malignancies. Citation Format: Steve T. Durant, Kurt G. Pike, Nicola Colclough, Lucy Riches, Antonio Garcia-Trinidad, Thomas Hunt, Stephanie Ling, Jonathan Stott, Ian Barrett, Li Zheng, Yingchun Wang, Kan Chen, Tianwei Zhang, Venkatesh Pilla Reddy, Andrew Sykes, Peter Johnstrom, Gemma Jones, Andrew Pierce, Jeremy Karlin, Jenna Kahn, Jasmine Allen, Kristoffer Valerie, Ruth Illingworth, Martin Pass. AZD1390, a potent and selective orally bioavailable blood-brain barrier-penetrant ATM inhibitor, radiosensitizes and improves survival of orthotopic glioma and metastatic brain tumor models [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 A104.

It is well established that Janus kinase (JAK) tyrosine kinases play a key role in the activation of STAT6 by IL-4. In this study, we investigated additional molecules involved in this process. We previously found that IL-4 and TNF-α cooperate in the activation of STAT6 and NF-κB, suggesting that these transcription factors are regulated by common intracellular signaling pathways. To test this hypothesis, we analyzed the effect of known inhibitors of NF-κB on the activation of STAT6. We discovered that inhibitors of phosphatidylcholine-specific phospholipase C (PC-PLC), but not other lipases, blocked the activation of STAT6 by IL-4. The activation of PC-PLC seems to be an early event in IL-4 signaling, because its inhibition abrogated JAK activation and STAT6 tyrosine phosphorylation. Interestingly, we found that the effects of pervanadate and sodium orthovanadate on STAT6 activation correspond to their effect on PC-PLC. Thus, pervanadate by itself activated PC-PLC, JAK, and STAT6, whereas sodium orthovanadate suppressed PC-PLC, JAK, and STAT6 activation by IL-4. We further found that PC-PLC activation is necessary but not sufficient to promote STAT6 activation, and therefore, additional intracellular pathways regulated by IL-4 and pervanadate may collaborate with PC-PLC to signal STAT6 activation. It has been reported that IL-4 signals PC-PLC activation; in this study, we provide evidence that this phospholipase plays a key role in IL-4 signaling.

Mutations in K-Ras commonly occur in colorectal, pancreatic and lung cancer, whereas mutations in BRAF are frequently found in melanomas. In past years, several studies have pointed to the role of Ras/Raf in the control of several metabolism pathways including glycolysis, mitochondrial respiration and glutamine metabolism [1-4]. The PDC complex is one of the central enzymes in the aerobic metabolism which converts the pyruvate produced during the glycolysis into Acetyl CoA used in the TCA cycle. In this work we show a pronounced sensitivity to PDHK-4 depletion in different mutant K-Ras cell lines, resulting in an increase of cell death and inhibition of cell growth in colorectal and lung tumor cell lines. Interestingly, cells expressing wild type K-Ras were signifinantly resistant to PDHK-4 depletion. This sensitivity in mutant Ras cells was correlated with a decrease in ERK phosphorylation, suggesting a possible inactivation in the Ras signaling pathway after PDHK-4 knock-down. Further studies will allow us to understand the biological mechanism by which Ras function is affecting the metabolic pathways involved in the regulation of PDC complex in cancer cells. Understanding the link between the PDC complex and Ras could be relevant to target cancer progression more effectively.