Publications by authors named "Barry R Davies"

57 Publications

Design and optimisation of dendrimer-conjugated Bcl-2/x inhibitor, AZD0466, with improved therapeutic index for cancer therapy.

Commun Biol 2021 Jan 25;4(1):112. Epub 2021 Jan 25.

Pharmaceutical Sciences, R&D, AstraZeneca, Macclesfield, SK10 2NA, UK.

Dual Bcl-2/Bcl-x inhibitors are expected to deliver therapeutic benefit in many haematological and solid malignancies, however, their use is limited by tolerability issues. AZD4320, a potent dual Bcl-2/Bcl-x inhibitor, has shown good efficacy however had dose limiting cardiovascular toxicity in preclinical species, coupled with challenging physicochemical properties, which prevented its clinical development. Here, we describe the design and development of AZD0466, a drug-dendrimer conjugate, where AZD4320 is chemically conjugated to a PEGylated poly-lysine dendrimer. Mathematical modelling was employed to determine the optimal release rate of the drug from the dendrimer for maximal therapeutic index in terms of preclinical anti-tumour efficacy and cardiovascular tolerability. The optimised candidate is shown to be efficacious and better tolerated in preclinical models compared with AZD4320 alone. The AZD4320-dendrimer conjugate (AZD0466) identified, through mathematical modelling, has resulted in an improved therapeutic index and thus enabled progression of this promising dual Bcl-2/Bcl-x inhibitor into clinical development.
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http://dx.doi.org/10.1038/s42003-020-01631-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7835349PMC
January 2021

AZD4320, A Dual Inhibitor of Bcl-2 and Bcl-x, Induces Tumor Regression in Hematologic Cancer Models without Dose-limiting Thrombocytopenia.

Clin Cancer Res 2020 Dec 28;26(24):6535-6549. Epub 2020 Sep 28.

DMPK, Oncology R&D, AstraZeneca, Boston, Massachusetts.

Purpose: Targeting Bcl-2 family members upregulated in multiple cancers has emerged as an important area of cancer therapeutics. While venetoclax, a Bcl-2-selective inhibitor, has had success in the clinic, another family member, Bcl-x, has also emerged as an important target and as a mechanism of resistance. Therefore, we developed a dual Bcl-2/Bcl-x inhibitor that broadens the therapeutic activity while minimizing Bcl-x-mediated thrombocytopenia.

Experimental Design: We used structure-based chemistry to design a small-molecule inhibitor of Bcl-2 and Bcl-x and assessed the activity against cell lines, patient samples, and models. We applied pharmacokinetic/pharmacodynamic (PK/PD) modeling to integrate our understanding of on-target activity of the dual inhibitor in tumors and platelets across dose levels and over time.

Results: We discovered AZD4320, which has nanomolar affinity for Bcl-2 and Bcl-x, and mechanistically drives cell death through the mitochondrial apoptotic pathway. AZD4320 demonstrates activity in both Bcl-2- and Bcl-x-dependent hematologic cancer cell lines and enhanced activity in acute myeloid leukemia (AML) patient samples compared with the Bcl-2-selective agent venetoclax. A single intravenous bolus dose of AZD4320 induces tumor regression with transient thrombocytopenia, which recovers in less than a week, suggesting a clinical weekly schedule would enable targeting of Bcl-2/Bcl-x-dependent tumors without incurring dose-limiting thrombocytopenia. AZD4320 demonstrates monotherapy activity in patient-derived AML and venetoclax-resistant xenograft models.

Conclusions: AZD4320 is a potent molecule with manageable thrombocytopenia risk to explore the utility of a dual Bcl-2/Bcl-x inhibitor across a broad range of tumor types with dysregulation of Bcl-2 prosurvival proteins.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-0863DOI Listing
December 2020

Genetic Alterations in the PI3K/AKT Pathway and Baseline AKT Activity Define AKT Inhibitor Sensitivity in Breast Cancer Patient-derived Xenografts.

Clin Cancer Res 2020 Jul 27;26(14):3720-3731. Epub 2020 Mar 27.

Experimental Therapeutics Group, Vall d'Hebron Institute of Oncology, Barcelona, Spain.

Purpose: AZD5363/capivasertib is a pan-AKT catalytic inhibitor with promising activity in combination with paclitaxel in triple-negative metastatic breast cancer harboring PI3K/AKT-pathway alterations and in estrogen receptor-positive breast cancer in combination with fulvestrant. Here, we aimed to identify response biomarkers and uncover mechanisms of resistance to AZD5363 and its combination with paclitaxel.

Experimental Design: Genetic and proteomic markers were analyzed in 28 HER2-negative patient-derived xenografts (PDXs) and in patient samples, and correlated to AZD5363 sensitivity as single agent and in combination with paclitaxel.

Results: Four PDX were derived from patients receiving AZD5363 in the clinic which exhibited concordant treatment response. Mutations in / and absence of mTOR complex 1 (mTORC1)-activating alterations, for example, in or , were associated with sensitivity to AZD5363 monotherapy. Interestingly, excluding from the composite biomarker increased its accuracy from 64% to 89%. Moreover, resistant PDXs exhibited low baseline pAKT S473 and residual pS6 S235 upon treatment, suggesting that parallel pathways bypass AKT/S6K1 signaling in these models. We identified two mechanisms of acquired resistance to AZD5363: cyclin D1 overexpression and loss of p.E17K.

Conclusions: This study provides insight into putative predictive biomarkers of response and acquired resistance to AZD5363 in HER2-negative metastatic breast cancer.
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http://dx.doi.org/10.1158/1078-0432.CCR-19-3324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7814659PMC
July 2020

The Discovery of 7-Methyl-2-[(7-methyl[1,2,4]triazolo[1,5-]pyridin-6-yl)amino]-9-(tetrahydro-2-pyran-4-yl)-7,9-dihydro-8-purin-8-one (AZD7648), a Potent and Selective DNA-Dependent Protein Kinase (DNA-PK) Inhibitor.

J Med Chem 2020 04 15;63(7):3461-3471. Epub 2020 Jan 15.

Oncology R&D, AstraZeneca, Cambridge CB4 0FZ, U.K.

DNA-PK is a key component within the DNA damage response, as it is responsible for recognizing and repairing double-strand DNA breaks (DSBs) via non-homologous end joining. Historically it has been challenging to identify inhibitors of the DNA-PK catalytic subunit (DNA-PKcs) with good selectivity versus the structurally related PI3 (lipid) and PI3K-related protein kinases. We screened our corporate collection for DNA-PKcs inhibitors with good PI3 kinase selectivity, identifying compound . Optimization focused on further improving selectivity while improving physical and pharmacokinetic properties, notably co-optimization of permeability and metabolic stability, to identify compound (AZD7648). Compound had no significant off-target activity in the protein kinome and only weak activity versus PI3Kα/γ lipid kinases. Monotherapy activity in murine xenograft models was observed, and regressions were observed when combined with inducers of DSBs (doxorubicin or irradiation) or PARP inhibition (olaparib). These data support progression into clinical studies (NCT03907969).
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http://dx.doi.org/10.1021/acs.jmedchem.9b01684DOI Listing
April 2020

AZD7648 is a potent and selective DNA-PK inhibitor that enhances radiation, chemotherapy and olaparib activity.

Nat Commun 2019 11 7;10(1):5065. Epub 2019 Nov 7.

Bioscience, Oncology R&D, AstraZeneca, Cambridge, UK.

DNA-dependent protein kinase (DNA-PK) is a critical player in the DNA damage response (DDR) and instrumental in the non-homologous end-joining pathway (NHEJ) used to detect and repair DNA double-strand breaks (DSBs). We demonstrate that the potent and highly selective DNA-PK inhibitor, AZD7648, is an efficient sensitizer of radiation- and doxorubicin-induced DNA damage, with combinations in xenograft and patient-derived xenograft (PDX) models inducing sustained regressions. Using ATM-deficient cells, we demonstrate that AZD7648, in combination with the PARP inhibitor olaparib, increases genomic instability, resulting in cell growth inhibition and apoptosis. AZD7648 enhanced olaparib efficacy across a range of doses and schedules in xenograft and PDX models, enabling sustained tumour regression and providing a clear rationale for its clinical investigation. Through its differentiated mechanism of action as an NHEJ inhibitor, AZD7648 complements the current armamentarium of DDR-targeted agents and has potential in combination with these agents to achieve deeper responses to current therapies.
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http://dx.doi.org/10.1038/s41467-019-12836-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6838110PMC
November 2019

Targeting castration-resistant prostate cancer with androgen receptor antisense oligonucleotide therapy.

JCI Insight 2019 09 5;4(17). Epub 2019 Sep 5.

Department of Urology and.

Sustained therapeutic responses from traditional and next-generation antiandrogen therapies remain elusive in clinical practice due to inherent and/or acquired resistance resulting in persistent androgen receptor (AR) activity. Antisense oligonucleotides (ASO) have the ability to block target gene expression and associated protein products and provide an alternate treatment strategy for castration-resistant prostate cancer (CRPC). We demonstrate the efficacy and therapeutic potential of this approach with a Generation-2.5 ASO targeting the mouse AR in genetically engineered models of prostate cancer. Furthermore, reciprocal feedback between AR and PI3K/AKT signaling was circumvented using a combination approach of AR-ASO therapy with the potent pan-AKT inhibitor, AZD5363. This treatment strategy effectively improved treatment responses and prolonged survival in a clinically relevant mouse model of advanced CRPC. Thus, our data provide preclinical evidence to support a combination strategy of next-generation ASOs targeting AR in combination with AKT inhibition as a potentially beneficial treatment approach for CRPC.
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http://dx.doi.org/10.1172/jci.insight.122688DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6777919PMC
September 2019

Preclinical Evaluation of AZ12601011 and AZ12799734, Inhibitors of Transforming Growth Factor Superfamily Type 1 Receptors.

Mol Pharmacol 2019 02 20;95(2):222-234. Epub 2018 Nov 20.

Cancer Research UK Beatson Institute, Garscube Estate, Bearsden, Glasgow, United Kingdom (L.C.S., G.J.F., B.H., O.J.S., G.J.I.);Institute of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom (O.J.S., G.J.I.) Division of Cellular Medicine, School of Medicine, University of Dundee, Dundee, United Kingdom (R.G.T., L.S.S.); and AstraZeneca Bioscience, Oncology (G.D.H., S.T.B., B.R.D.) and Medicinal Chemistry, Oncology (F.W.G.), IMED Biotech Unit, AstraZeneca, Cambridge, United Kingdom

The transforming growth factor (TGF) superfamily includes TGF, activins, inhibins, and bone morphogenetic proteins (BMPs). These extracellular ligands have essential roles in normal tissue homeostasis by coordinately regulating cell proliferation, differentiation, and migration. Aberrant signaling of superfamily members, however, is associated with fibrosis as well as tumorigenesis, cancer progression, metastasis, and drug-resistance mechanisms in a variety of cancer subtypes. Given their involvement in human disease, the identification of novel selective inhibitors of TGF superfamily receptors is an attractive therapeutic approach. Seven mammalian type 1 receptors have been identified that have context-specific roles depending on the ligand and the complex formation with the type 2 receptor. Here, we characterize the biologic effects of two transforming growth factor receptor 1 (TGFBR1) kinase inhibitors designed to target TGF signaling. AZ12601011 [2-(2-pyridinyl)-4-(1H-pyrrolo[3,2-c]pyridin-1-yl)-6,7-dihydro-5H-cyclopenta[d]pyrimidine]; structure previously undisclosed] and AZ12799734 [4-({4-[(2,6-dimethyl-3-pyridinyl)oxy]-2-pyridinyl}amino)benzenesulfonamide] (IC = 18 and 47 nM, respectively) were more effective inhibitors of TGF-induced reporter activity than SB-431542 [4-[4-(1,3-benzodioxol-5-yl)-5-(2-pyridinyl)-1H-imidazol-2-yl]benzamide] (IC = 84 nM) and LY2157299 [4-[2-(6-methylpyridin-2-yl)-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazol-3-yl]quinoline-6-carboxamide monohydrate]] (galunisertib) (IC = 380 nM). AZ12601011 inhibited phosphorylation of SMAD2 via the type 1 receptors activin A receptor type 1B (ALK4), TGFBR1, and activin A receptor type 1C (ALK7). AZ12799734, however, is a pan TGF/BMP inhibitor, inhibiting receptor-mediated phosphorylation of SMAD1 by activin A receptor type 1L, bone morphogenetic protein receptor type 1A, and bone morphogenetic protein receptor type 1B and phosphorylation of SMAD2 by ALK4, TGFBR1, and ALK7. AZ12601011 was highly effective at inhibiting basal and TGF-induced migration of HaCaT keratinocytes and, furthermore, inhibited tumor growth and metastasis to the lungs in a 4T1 syngeneic orthotopic mammary tumor model. These inhibitors provide new reagents for investigating in vitro and in vivo pathogenic processes and the contribution of TGF- and BMP-regulated signaling pathways to disease states.
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http://dx.doi.org/10.1124/mol.118.112946DOI Listing
February 2019

Optimizing the design of population-based patient-derived tumor xenograft studies to better predict clinical response.

Dis Model Mech 2018 10 31;11(11). Epub 2018 Oct 31.

Quantitative Biology, Discovery Sciences, IMED Biotech Unit, AstraZeneca, Cambridge CB4 0WG, UK

The high attrition rate of preclinical agents entering oncology clinical trials has been associated with poor understanding of the heterogeneous patient response, arising from limitations in the preclinical pipeline with cancer models. Patient-derived tumor xenograft (PDX) models have been shown to better recapitulate the patient drug response. However, the platform of evidence generated to support clinical development in a drug discovery project typically employs a limited number of models, which may not accurately predict the response at a population level. Population PDX studies, large-scale screens of PDX models, have been proposed as a strategy to model the patient inter-tumor heterogeneity. Here, we present a freely available interactive tool that explores the design of a population PDX study and how it impacts the sensitivity and false-positive rate experienced. We discuss the reflection process needed to optimize the design for the therapeutic landscape being studied and manage the risk of false-negative and false-positive outcomes that the sponsor is willing to take. The tool has been made freely available to allow the optimal design to be determined for each drug-disease area. This will allow researchers to improve their understanding of treatment efficacy in the presence of genetic variability before taking a drug to clinic. In addition, the tool serves to refine the number of animals to be used for population-based PDX studies, ensuring researchers meet their ethical obligation when performing animal research.
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http://dx.doi.org/10.1242/dmm.036160DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6262806PMC
October 2018

Delineating the distinct role of AKT in mediating cell survival and proliferation induced by CD154 and IL-4/IL-21 in chronic lymphocytic leukemia.

Oncotarget 2017 Nov 7;8(61):102948-102964. Epub 2017 Nov 7.

Department of Molecular and Clinical Cancer Medicine, University of Liverpool, Liverpool, UK.

The functional significance of AKT in chronic lymphocytic leukemia (CLL) remains unclear. Given the importance of non-malignant T cells in regulating clonal expansion in CLL, we investigated the role of AKT in T cell-mediated cytoprotection and proliferation using an established co-culture system in which primary CLL cells were incubated on a monolayer of transfected mouse fibroblasts expressing human CD40L (CD154). Stimulation of CLL cells via CD40 induced activation of AKT, which was closely associated with downregulation of its negative regulator PTEN, and protected CLL cells from killing by bendamustine. This cytoprotective effect of CD40 stimulation was prevented by a selective inhibitor of AKT. Stimulation of CLL cells with CD154 + IL-4 or IL-21 induced proliferation detected as reduced fluorescence of cells pre-stained with CFSE. AKT inhibition produced a significant, consistent reduction in proliferation induced by CD154 + IL-4 and a reduction in proliferation induced by CD154 + IL-21 in most but not all cases. In contrast, AKT inhibition had no effect on the proliferation of normal B cells induced by CD154 + IL-4 or IL-21. These findings indicate that AKT contributes in a significant way to T-cell mediated survival and proliferation signalling in CLL and support the clinical evaluation of AKT inhibitors in this disease.
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http://dx.doi.org/10.18632/oncotarget.22292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5732702PMC
November 2017

Akt inhibition improves long-term tumour control following radiotherapy by altering the microenvironment.

EMBO Mol Med 2017 12;9(12):1646-1659

Division of Cancer Sciences, School of Medical Sciences, University of Manchester, Manchester, UK

Radiotherapy is an important anti-cancer treatment, but tumour recurrence remains a significant clinical problem. In an effort to improve outcomes further, targeted anti-cancer drugs are being tested in combination with radiotherapy. Here, we have studied the effects of Akt inhibition with AZD5363. AZD5363 administered as an adjuvant after radiotherapy to FaDu and PE/CA PJ34 tumours leads to long-term tumour control, which appears to be secondary to effects on the irradiated tumour microenvironment. AZD5363 reduces the downstream effectors VEGF and HIF-1α, but has no effect on tumour vascularity or oxygenation, or on tumour control, when administered prior to radiotherapy. In contrast, AZD5363 given after radiotherapy is associated with marked reductions in tumour vascular density, a decrease in the influx of CD11b myeloid cells and a failure of tumour regrowth. In addition, AZD5363 is shown to inhibit the proportion of proliferating tumour vascular endothelial cells which may contribute to improved tumour control with adjuvant treatment. These new insights provide promise to improve outcomes with the addition of AZD5363 as an adjuvant therapy following radiotherapy.
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http://dx.doi.org/10.15252/emmm.201707767DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5709765PMC
December 2017

A Phase I Open-Label Study to Identify a Dosing Regimen of the Pan-AKT Inhibitor AZD5363 for Evaluation in Solid Tumors and in -Mutated Breast and Gynecologic Cancers.

Clin Cancer Res 2018 05 24;24(9):2050-2059. Epub 2017 Oct 24.

Division of Medical Oncology, The Netherlands Cancer Institute, Amsterdam, the Netherlands.

This phase I, open-label study (Study 1, D3610C00001; NCT01226316) was the first-in-human evaluation of oral AZD5363, a selective pan-AKT inhibitor, in patients with advanced solid malignancies. The objectives were to investigate the safety, tolerability, and pharmacokinetics of AZD5363, define a recommended dosing schedule, and evaluate preliminary clinical activity. Patients were aged ≥18 years with World Health Organization (WHO) performance status of 0 to 1. Dose escalation was conducted within separate continuous and intermittent [4 days/week (4/7) or 2 days/week (2/7)] schedules with safety, pharmacokinetic, and pharmacodynamic analyses. Expansion cohorts of approximately 20 patients each explored AZD5363 activity in -mutant breast and gynecologic cancers. MTDs were 320, 480, and 640 mg for continuous ( = 47), 4/7 ( = 21), and 2/7 ( = 22) schedules, respectively. Dose-limiting toxicities were rash and diarrhea for continuous, hyperglycemia for 2/7, and none for 4/7. Common adverse events were diarrhea (78%) and nausea (49%) and, for Common Terminology Criteria for Adverse Events grade ≥3 events, hyperglycemia (20%). The recommended phase II dose (480 mg bid, 4/7 intermittent) was assessed in -mutant breast and gynecologic expansion cohorts: 46% and 56% of patients, respectively, showed a reduction in tumor size, with RECIST responses of 4% and 8%. These responses were less than the prespecified 20% response rate; therefore, the criteria to stop further recruitment to the -mutant cohort were met. At the recommended phase II dose, AZD5363 was well tolerated and achieved plasma levels and robust target modulation in tumors. Proof-of-concept responses were observed in patients with -mutant cancers treated with AZD5363. .
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http://dx.doi.org/10.1158/1078-0432.CCR-17-2260DOI Listing
May 2018

Inhibition of the PI3K/AKT/mTOR pathway activates autophagy and compensatory Ras/Raf/MEK/ERK signalling in prostate cancer.

Oncotarget 2017 Aug 23;8(34):56698-56713. Epub 2017 May 23.

The Cancer Research Unit, Department of Biology, University of York, York YO10 5DD, UK.

The PI3K/AKT/mTOR pathway is frequently activated in advanced prostate cancer, due to loss of the tumour suppressor PTEN, and is an important axis for drug development. We have assessed the molecular and functional consequences of pathway blockade by inhibiting AKT and mTOR kinases either in combination or as individual drug treatments. In established prostate cancer cell lines, a decrease in cell viability and in phospho-biomarker expression was observed. Although apoptosis was not induced, a G1 growth arrest was observed in PTEN null LNCaP cells, but not in BPH1 or PC3 cells. In contrast, when the AKT inhibitor AZD7328 was applied to patient-derived prostate cultures that retained expression of PTEN, activation of a compensatory Ras/MEK/ERK pathway was observed. Moreover, whilst autophagy was induced following treatment with AZD7328, cell viability was less affected in the patient-derived cultures than in cell lines. Surprisingly, treatment with a combination of both AZD7328 and two separate MEK1/2 inhibitors further enhanced phosphorylation of ERK1/2 in primary prostate cultures. However, it also induced irreversible growth arrest and senescence. treatment of a patient-derived xenograft (PDX) of prostate cancer with a combination of AZD7328 and the mTOR inhibitor KU-0063794, significantly reduced tumour frequency upon re-engraftment of tumour cells. The results demonstrate that single agent targeting of the PI3K/AKT/mTOR pathway triggers activation of the Ras/MEK/ERK compensatory pathway in near-patient samples. Therefore, blockade of one pathway is insufficient to treat prostate cancer in man.
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http://dx.doi.org/10.18632/oncotarget.18082DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5593594PMC
August 2017

A pharmacokinetic-pharmacodynamic model predicting tumour growth inhibition after intermittent administration with the mTOR kinase inhibitor AZD8055.

Br J Pharmacol 2017 Aug 6;174(16):2652-2661. Epub 2017 Jul 6.

AstraZeneca, Cambridge, UK.

Background And Purpose: AZD8055 is a potent orally available mTOR kinase inhibitor with in vitro and in vivo antitumour activity against a range of tumour types. Preclinical studies showed that AZD8055 induced a dose-dependent pharmacodynamic effect in xenograft models in vivo, but a lack of understanding of the relative contributions of the maximum inhibition of the biomarkers and the duration of inhibition to the antitumour effect, limited the rational design of experiments to optimize the dose and schedules of treatment.

Experimental Approach: In this study, a mathematical modelling approach was developed to relate pharmacodynamics and antitumour activity using preclinical data generated in mice bearing U87-MG xenografts.

Key Results: Refinement and validation of the model was carried out in a panel of additional human tumour xenograft models with different growth rates and different sensitivity to AZD8055 (from partial growth inhibition to regression). Finally, the model was applied to accurately predict the efficacy of high, intermittent dosing schedules of AZD8055.

Conclusions And Implications: Overall, this new model linking pharmacokinetics, pharmacodynamic biomarkers and efficacy across several tumour xenografts with different sensitivity to AZD8055 was able to identify the optimal dose and route of administration to maximize the antitumour efficacy in preclinical models and its potential for translation into man.
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http://dx.doi.org/10.1111/bph.13886DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5522991PMC
August 2017

Sensitivity to PI3K and AKT inhibitors is mediated by divergent molecular mechanisms in subtypes of DLBCL.

Blood 2017 07 15;130(3):310-322. Epub 2017 Feb 15.

Translational Oncology, University Hospital Münster, Münster, Germany.

Activated B-cell-like (ABC) and germinal center B-cell-like diffuse large B-cell lymphoma (DLBCL) represent the 2 major molecular DLBCL subtypes. They are characterized by differences in clinical course and by divergent addiction to oncogenic pathways. To determine activity of novel compounds in these 2 subtypes, we conducted an unbiased pharmacologic in vitro screen. The phosphatidylinositol-3-kinase (PI3K) α/δ (PI3Kα/δ) inhibitor AZD8835 showed marked potency in ABC DLBCL models, whereas the protein kinase B (AKT) inhibitor AZD5363 induced apoptosis in PTEN-deficient DLBCLs irrespective of their molecular subtype. These in vitro results were confirmed in various cell line xenograft and patient-derived xenograft mouse models in vivo. Treatment with AZD8835 induced inhibition of nuclear factor κB signaling, prompting us to combine AZD8835 with the Bruton's tyrosine kinase inhibitor ibrutinib. This combination was synergistic and effective both in vitro and in vivo. In contrast, the AKT inhibitor AZD5363 was effective in PTEN-deficient DLBCLs through downregulation of the oncogenic transcription factor MYC. Collectively, our data suggest that patients should be stratified according to their oncogenic dependencies when treated with PI3K and AKT inhibitors.
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http://dx.doi.org/10.1182/blood-2016-12-758599DOI Listing
July 2017

Combination treatment of prostate cancer with FGF receptor and AKT kinase inhibitors.

Oncotarget 2017 Jan;8(4):6179-6192

Department of Pathology and Immunology, Baylor College of Medicine and Michael E. DeBakey Department of Veterans Affairs Medical Center Baylor College of Medicine, Houston, 77030, TX, USA.

Activation of the PI3K/AKT pathway occurs in the vast majority of advanced prostate cancers (PCas). Activation of fibroblast growth factor receptor (FGFR) signaling occurs in a wide variety of malignancies, including PCa. RNA-Seq of castration resistant PCa revealed expression of multiple FGFR signaling components compatible with FGFR signaling in all cases, with multiple FGF ligands expressed in 90% of cases. Immunohistochemistry confirmed FGFR signaling in the majority of xenografts and advanced PCas. AZD5363, an AKT kinase inhibitor and AZD4547, a FGFR kinase inhibitor are under active clinical development. We therefore sought to determine if these two drugs have additive effects in PCa models. The effect of both agents, singly and in combination was evaluated in a variety of PCa cell lines in vitro and in vivo. All cell lines tested responded to both drugs with decreased invasion, soft agar colony formation and growth in vivo, with additive effects seen with combination treatment. Activation of the FGFR, AKT, ERK and STAT3 pathways was examined in treated cells. AZD5363 inhibited AKT signaling and increased FGFR1 signaling, which partially compensated for decreased AKT kinase activity. While AZD4547 could effectively block the ERK pathway, combination treatment was needed to completely block STAT3 activation. Thus combination treatment with AKT and FGFR kinase inhibitors have additive effects on malignant phenotypes in vitro and in vivo by inhibiting multiple signaling pathways and mitigating the compensatory upregulation of FGFR signaling induced by AKT kinase inhibition. Our studies suggest that co-targeting these pathways may be efficacious in advanced PCa.
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http://dx.doi.org/10.18632/oncotarget.14049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5351622PMC
January 2017

Identification of Pharmacodynamic Transcript Biomarkers in Response to FGFR Inhibition by AZD4547.

Mol Cancer Ther 2016 11 22;15(11):2802-2813. Epub 2016 Aug 22.

AstraZeneca Pharmaceutical, Oncology iMed, CRUK-CI, Li Ka Shing Centre, Cambridge, United Kingdom.

The challenge of developing effective pharmacodynamic biomarkers for preclinical and clinical testing of FGFR signaling inhibition is significant. Assays that rely on the measurement of phospho-protein epitopes can be limited by the availability of effective antibody detection reagents. Transcript profiling enables accurate quantification of many biomarkers and provides a broader representation of pathway modulation. To identify dynamic transcript biomarkers of FGFR signaling inhibition by AZD4547, a potent inhibitor of FGF receptors 1, 2, and 3, a gene expression profiling study was performed in FGFR2-amplified, drug-sensitive tumor cell lines. Consistent with known signaling pathways activated by FGFR, we identified transcript biomarkers downstream of the RAS-MAPK and PI3K/AKT pathways. Using different tumor cell lines in vitro and xenografts in vivo, we confirmed that some of these transcript biomarkers (DUSP6, ETV5, YPEL2) were modulated downstream of oncogenic FGFR1, 2, 3, whereas others showed selective modulation only by FGFR2 signaling (EGR1). These transcripts showed consistent time-dependent modulation, corresponding to the plasma exposure of AZD4547 and inhibition of phosphorylation of the downstream signaling molecules FRS2 or ERK. Combination of FGFR and AKT inhibition in an FGFR2-mutated endometrial cancer xenograft model enhanced modulation of transcript biomarkers from the PI3K/AKT pathway and tumor growth inhibition. These biomarkers were detected on the clinically validated nanoString platform. Taken together, these data identified novel dynamic transcript biomarkers of FGFR inhibition that were validated in a number of in vivo models, and which are more robustly modulated by FGFR inhibition than some conventional downstream signaling protein biomarkers. Mol Cancer Ther; 15(11); 2802-13. ©2016 AACR.
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http://dx.doi.org/10.1158/1535-7163.MCT-16-0297DOI Listing
November 2016

Identification of differential PI3K pathway target dependencies in T-cell acute lymphoblastic leukemia through a large cancer cell panel screen.

Oncotarget 2016 Apr;7(16):22128-39

Oncology iMED, AstraZeneca, Alderley Park, Macclesfield, SK10 4TG, United Kingdom.

Selective phosphoinositide 3-kinase (PI3K)/AKT/mTOR inhibitors are currently under evaluation in clinical studies. To identify tumor types that are sensitive to PI3K pathway inhibitors we screened compounds targeting PI3Kα/δ (AZD8835), PI3Kβ/δ (AZD8186), AKT (AZD5363) and mTORC1/2 (AZD2014) against a cancer cell line panel (971 cell lines). There was an enrichment of hematological malignancies that were sensitive to AKT and mTOR inhibition, with the greatest degree of sensitivity observed in T-cell acute lymphoblastic leukemia (T-ALL). We found that all NOTCH mutant T-ALL cell lines were sensitive to AKT and mTORC1/2 inhibitors, with only partial sensitivity to agents that target the PI3K α, β or δ isoforms. Induction of apoptosis only occurred following AKTi treatment in cell lines with PTEN protein loss and high levels of active AKT. In summary, we have demonstrated that T-ALL cell lines show differential sensitivity to inhibition at different nodes in the PI3K/AKT/mTOR pathway and inhibiting AKT or mTOR may have a therapeutic benefit in this disease setting.
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http://dx.doi.org/10.18632/oncotarget.8031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5008349PMC
April 2016

Efficacy of targeted AKT inhibition in genetically engineered mouse models of PTEN-deficient prostate cancer.

Oncotarget 2016 Mar;7(13):15959-76

Department of Urology, Kinki University Faculty of Medicine, Osaka-Sayama, Osaka, Japan.

The PI3K/AKT pathway is frequently altered in advanced human prostate cancer mainly through the loss of functional PTEN, and presents as potential target for personalized therapy. Our aim was to determine the therapeutic potential of the pan-AKT inhibitor, AZD5363, in PTEN-deficient prostate cancer. Here we used a genetically engineered mouse (GEM) model of PTEN-deficient prostate cancer to evaluate the in vivo pharmacodynamic and antitumor activity of AZD5363 in castration-naïve and castration-resistant prostate cancer. An additional GEM model, based on the concomitant inactivation of PTEN and Trp53 (P53), was established as an aggressive model of advanced prostate cancer and was used to further evaluate clinically relevant endpoints after treatment with AZD5363. In vivo pharmacodynamic studies demonstrated that AZD5363 effectively inhibited downstream targets of AKT. AZD5363 monotherapy significantly reduced growth of tumors in castration-naïve and castration-resistant models of PTEN-deficient prostate cancer. More importantly, AZD5363 significantly delayed tumor growth and improved overall survival and progression-free survival in PTEN/P53 double knockout mice. Our findings demonstrate that AZD5363 is effective against GEM models of PTEN-deficient prostate cancer and provide lines of evidence to support further investigation into the development of treatment strategies targeting AKT for the treatment of PTEN-deficient prostate cancer.
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http://dx.doi.org/10.18632/oncotarget.7557DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4941290PMC
March 2016

Differential regulation of mTOR signaling determines sensitivity to AKT inhibition in diffuse large B cell lymphoma.

Oncotarget 2016 Feb;7(8):9163-74

AstraZeneca Oncology, Waltham, Massachusetts, MA, USA.

Agents that target components of the PI3K/AKT/mTOR pathway are under investigation for the treatment of diffuse large B cell lymphoma (DLBCL). Given the highly heterogeneous nature of DLBCL, it is not clear whether all subtypes of DLBCL will be susceptible to PI3K pathway inhibition, or which kinase within this pathway is the most favorable target. Pharmacological profiling of a panel of DLBCL cell lines revealed a subset of DLBCL that was resistant to AKT inhibition. Strikingly, sensitivity to AKT inhibitors correlated with the ability of these inhibitors to block phosphorylation of S6K1 and ribosomal protein S6. Cell lines resistant to AKT inhibition activated S6K1 independent of AKT either through upregulation of PIM2 or through activation by B cell receptor (BCR) signaling components. Finally, combined inhibition of AKT and BTK, PIM2, or S6K1 proved to be an effective strategy to overcome resistance to AKT inhibition in DLBCL.
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http://dx.doi.org/10.18632/oncotarget.7036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4891033PMC
February 2016

AZD2014, an Inhibitor of mTORC1 and mTORC2, Is Highly Effective in ER+ Breast Cancer When Administered Using Intermittent or Continuous Schedules.

Mol Cancer Ther 2015 Nov 10;14(11):2508-18. Epub 2015 Sep 10.

AstraZeneca Oncology, CRUK Cambridge Institute, Cambridge, United Kingdom.

mTOR is an atypical serine threonine kinase involved in regulating major cellular functions, such as nutrients sensing, growth, and proliferation. mTOR is part of the multiprotein complexes mTORC1 and mTORC2, which have been shown to play critical yet functionally distinct roles in the regulation of cellular processes. Current clinical mTOR inhibitors only inhibit the mTORC1 complex and are derivatives of the macrolide rapamycin (rapalogs). Encouraging effects have been observed with rapalogs in estrogen receptor-positive (ER(+)) breast cancer patients in combination with endocrine therapy, such as aromatase inhibitors. AZD2014 is a small-molecule ATP competitive inhibitor of mTOR that inhibits both mTORC1 and mTORC2 complexes and has a greater inhibitory function against mTORC1 than the clinically approved rapalogs. Here, we demonstrate that AZD2014 has broad antiproliferative effects across multiple cell lines, including ER(+) breast models with acquired resistance to hormonal therapy and cell lines with acquired resistance to rapalogs. In vivo, AZD2014 induces dose-dependent tumor growth inhibition in several xenograft and primary explant models. The antitumor activity of AZD2014 is associated with modulation of both mTORC1 and mTORC2 substrates, consistent with its mechanism of action. In combination with fulvestrant, AZD2014 induces tumor regressions when dosed continuously or using intermittent dosing schedules. The ability to dose AZD2014 intermittently, together with its ability to block signaling from both mTORC1 and mTORC2 complexes, makes this compound an ideal candidate for combining with endocrine therapies in the clinic. AZD2014 is currently in phase II clinical trials.
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http://dx.doi.org/10.1158/1535-7163.MCT-15-0365DOI Listing
November 2015

Tumors with AKT1E17K Mutations Are Rational Targets for Single Agent or Combination Therapy with AKT Inhibitors.

Mol Cancer Ther 2015 Nov 8;14(11):2441-51. Epub 2015 Sep 8.

Gatehouse Park, Waltham, Massachusetts.

AKT1(E17K) mutations occur at low frequency in a variety of solid tumors, including those of the breast and urinary bladder. Although this mutation has been shown to transform rodent cells in culture, it was found to be less oncogenic than PIK3CA mutations in breast epithelial cells. Moreover, the therapeutic potential of AKT inhibitors in human tumors with an endogenous AKT1(E17K) mutation is not known. Expression of exogenous copies of AKT1(E17K) in MCF10A breast epithelial cells increased phosphorylation of AKT and its substrates, induced colony formation in soft agar, and formation of lesions in the mammary fat pad of immunodeficient mice. These effects were inhibited by the allosteric and catalytic AKT inhibitors MK-2206 and AZD5363, respectively. Both AKT inhibitors caused highly significant growth inhibition of breast cancer explant models with AKT1(E17K) mutation. Furthermore, in a phase I clinical study, the catalytic Akt inhibitor AZD5363 induced partial responses in patients with breast and ovarian cancer with tumors containing AKT1(E17K) mutations. In MGH-U3 bladder cancer xenografts, which contain both AKT1(E17K) and FGFR3(Y373C) mutations, AZD5363 monotherapy did not significantly reduce tumor growth, but tumor regression was observed in combination with the FGFR inhibitor AZD4547. The data show that tumors with AKT1(E17K) mutations are rational therapeutic targets for AKT inhibitors, although combinations with other targeted agents may be required where activating oncogenic mutations of other proteins are present in the same tumor.
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http://dx.doi.org/10.1158/1535-7163.MCT-15-0230DOI Listing
November 2015

Development and exploitation of a novel mutant androgen receptor modelling strategy to identify new targets for advanced prostate cancer therapy.

Oncotarget 2015 Sep;6(28):26029-40

Northern Institute for Cancer Research, Newcastle University, Newcastle Upon Tyne, NE2 4HH, UK.

The persistence of androgen receptor (AR) signalling in castrate-resistant prostate cancer (CRPC) highlights the unmet clinical need for the development of more effective AR targeting therapies. A key mechanism of therapy-resistance is by selection of AR mutations that convert anti-androgens to agonists enabling the retention of androgenic signalling in CRPC. To improve our understanding of these receptors in advanced disease we developed a physiologically-relevant model to analyse the global functionality of AR mutants in CRPC. Using the bicalutamide-activated AR(W741L/C) mutation as proof of concept, we demonstrate that this mutant confers an androgenic-like signalling programme and growth promoting phenotype in the presence of bicalutamide. Transcriptomic profiling of AR(W741L) highlighted key genes markedly up-regulated by the mutant receptor, including TIPARP, RASD1 and SGK1. Importantly, SGK1 expression was found to be highly expressed in the KUCaP xenograft model and a CRPC patient biopsy sample both of which express the bicalutamide-activated receptor mutant. Using an SGK1 inhibitor, AR(W741L) transcriptional and growth promoting activity was reduced indicating that exploiting functional distinctions between receptor isoforms in our model may provide new and effective therapies for CRPC patients.
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http://dx.doi.org/10.18632/oncotarget.4347DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4694883PMC
September 2015

AKT Antagonist AZD5363 Influences Estrogen Receptor Function in Endocrine-Resistant Breast Cancer and Synergizes with Fulvestrant (ICI182780) In Vivo.

Mol Cancer Ther 2015 Sep 26;14(9):2035-48. Epub 2015 Jun 26.

Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, United Kingdom.

PI3K/AKT/mTOR signaling plays an important role in breast cancer. Its interaction with estrogen receptor (ER) signaling becomes more complex and interdependent with acquired endocrine resistance. Targeting mTOR combined with endocrine therapy has shown clinical utility; however, a negative feedback loop exists downstream of PI3K/AKT/mTOR. Direct blockade of AKT together with endocrine therapy may improve breast cancer treatment. AZD5363, a novel pan-AKT kinase catalytic inhibitor, was examined in a panel of ER(+) breast cancer cell lines (MCF7, HCC1428, T47D, ZR75.1) adapted to long-term estrogen deprivation (LTED) or tamoxifen (TamR). AZD5363 caused a dose-dependent decrease in proliferation in all cell lines tested (GI50 < 500 nmol/L) except HCC1428 and HCC1428-LTED. T47D-LTED and ZR75-LTED were the most sensitive of the lines (GI50 ∼ 100 nmol/L). AZD5363 resensitized TamR cells to tamoxifen and acted synergistically with fulvestrant. AZD5363 decreased p-AKT/mTOR targets leading to a reduction in ERα-mediated transcription in a context-specific manner and concomitant decrease in recruitment of ER and CREB-binding protein (CBP) to estrogen response elements located on the TFF1, PGR, and GREB1 promoters. Furthermore, AZD5363 reduced expression of cell-cycle-regulatory proteins. Global gene expression highlighted ERBB2-ERBB3, ERK5, and IGFI signaling pathways driven by MYC as potential feedback-loops. Combined treatment with AZD5363 and fulvestrant showed synergy in an ER(+) patient-derived xenograft and delayed tumor progression after cessation of therapy. These data support the combination of AZD5363 with fulvestrant as a potential therapy for breast cancer that is sensitive or resistant to E-deprivation or tamoxifen and that activated AKT is a determinant of response, supporting the need for clinical evaluation.
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http://dx.doi.org/10.1158/1535-7163.MCT-15-0143DOI Listing
September 2015

Combining AZD8931, a novel EGFR/HER2/HER3 signalling inhibitor, with AZD5363 limits AKT inhibitor induced feedback and enhances antitumour efficacy in HER2-amplified breast cancer models.

Int J Oncol 2015 Aug 22;47(2):446-54. Epub 2015 Jun 22.

Oncology iMED, AstraZeneca, Alderley Park, Macclesfield SK10 4TG, UK.

The phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signalling network is frequently de-regulated in breast cancer and has been shown to mediate resistance to anti-HER2 agents. Whilst constitutive activation of this pathway is emerging as a marker of sensitivity to various PI3K pathway inhibitors, activity of these agents in the clinic may be limited by the presence of feedback loops, leading to reactivation of receptor tyrosine kinases, such as HER2/HER3. To determine whether inhibition of HER2 could increase the efficacy of AZD5363, a novel AKT inhibitor, a panel of breast cancer cells was dosed with AZD5363 in combination with AZD8931, an inhibitor of EGFR/HER2/HER3 signalling. We show that the combined treatment resulted in synergistic growth inhibition and enhanced cell death, specifically in the HER2-amplified cell lines. Investigation of the mechanism by western blot analysis revealed that the addition of AZD8931 prevented the induction of HER2/HER3 phosphorylation induced by AZD5363 and resulted in concomitant inhibition of both the PI3K/AKT/mTOR and ERK signalling pathways and induction of apoptosis. Using the HCC1954 xenograft model, which is resistant to trastuzumab, we show that the combination of AZD5363 and AZD8931 is more efficacious than either agent alone, resulting in profound tumour regressions. We conclude that the activity of AZD5363 in HER2-amplified breast cancer cells is enhanced by the addition of AZD8931 and that dual targeting of AKT and EGFR/HER2/HER3 signalling is an attractive treatment option to be explored in the clinic.
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http://dx.doi.org/10.3892/ijo.2015.3062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4501645PMC
August 2015

Validation of a predictive modeling approach to demonstrate the relative efficacy of three different schedules of the AKT inhibitor AZD5363.

Cancer Chemother Pharmacol 2015 Aug 20;76(2):343-56. Epub 2015 Jun 20.

Oncology iMED, AstraZeneca, Alderley Park, Mereside, Macclesfield, Cheshire, SK10 4TG, UK,

Purpose: Intermittent dosing of inhibitors of the PI3K/AKT/mTOR network offers the potential to maximize the therapeutic margin. Here, we validate a predictive modeling approach to establish the relative efficacy of continuous and two intermittent dosing schedules of the AKT inhibitor AZD5363.

Methods: A mathematical model of pharmacokinetics, pharmacodynamics and anti-tumor effect was constructed based upon experimental data from dosing regimens that give constant and transient inhibition of the AKT pathway.

Results: Continuous and intermittent dosing of AZD5363 inhibited growth of BT474c xenografts and caused dose- and time-dependent inhibition of AKT substrate phosphorylation. Both dosing schedules inhibited proliferation, but a higher intermittent dose also induced apoptosis. The mathematical model described this pharmacodynamic and efficacy data well, for both monotherapy and combination dosing with docetaxel, and predicted that equivalent efficacy could be achieved at 1.3- and 1.7× continuous dose when AZD5363 was dosed intermittently for 4 and 2 days per week, respectively. These predictions were confirmed in two independent xenograft models. Moreover, the model also correctly predicted the relative efficacy of three different sequences of intermittent dosing of AZD5363 with docetaxel.

Conclusions: Equivalent anti-tumor activity to continuous dosing can be achieved at modestly increased intermittent doses of AZD5363. These intermittent dosing regimens may potentially overcome tolerability issues seen with continuous dosing and enable greater flexibility of dosing schedule in combination with other agents, including chemotherapy.
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http://dx.doi.org/10.1007/s00280-015-2795-7DOI Listing
August 2015

Inhibition of PI3Kβ signaling with AZD8186 inhibits growth of PTEN-deficient breast and prostate tumors alone and in combination with docetaxel.

Mol Cancer Ther 2015 Jan 14;14(1):48-58. Epub 2014 Nov 14.

Oncology Innovative Medicines, AstraZeneca, Alderley Park, Macclesfield, Cheshire, United Kingdom.

Loss of PTEN protein results in upregulation of the PI3K/AKT pathway, which appears dependent on the PI3Kβ isoform. Inhibitors of PI3Kβ have potential to reduce growth of tumors in which loss of PTEN drives tumor progression. We have developed a small-molecule inhibitor of PI3Kβ and PI3Kδ (AZD8186) and assessed its antitumor activity across a panel of cell lines. We have then explored the antitumor effects as single agent and in combination with docetaxel in triple-negative breast (TNBC) and prostate cancer models. In vitro, AZD8186 inhibited growth of a range of cell lines. Sensitivity was associated with inhibition of the AKT pathway. Cells sensitive to AZD8186 (GI50 < 1 μmol/L) are enriched for, but not exclusively associated with, PTEN deficiency. In vivo, AZD8186 inhibits PI3K pathway biomarkers in prostate and TNBC tumors. Scheduling treatment with AZD8186 shows antitumor activity required only intermittent exposure, and that increased tumor control is achieved when AZD8186 is used in combination with docetaxel. AZD8186 is a potent inhibitor of PI3Kβ with activity against PI3Kδ signaling, and has potential to reduce growth of tumors dependent on dysregulated PTEN for growth. Moreover, AZD8186 can be combined with docetaxel, a chemotherapy commonly used to treat advanced TBNC and prostate tumors. The ability to schedule AZD8186 and maintain efficacy offers opportunity to combine AZD8186 more effectively with other drugs.
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http://dx.doi.org/10.1158/1535-7163.MCT-14-0406DOI Listing
January 2015

High Efficacy of Combination Therapy Using PI3K/AKT Inhibitors with Androgen Deprivation in Prostate Cancer Preclinical Models.

Eur Urol 2015 Jun 12;67(6):1177-1185. Epub 2014 Sep 12.

Department of Urology, Erasmus MC, University Medical Center Rotterdam, The Netherlands.

Background: The phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT pathway is frequently activated during prostate cancer (PCa) progression through loss or mutation of the phosphatase and tensin homolog (PTEN) gene. Following the androgen receptor (AR) pathway, it is the second major driver of PCa growth.

Objective: To assess efficacy of novel PI3K/AKT-targeted therapies in PCa models, as a single agent and in combination with androgen deprivation.

Design, Setting, And Participants: Twelve human PCa cell lines were tested in vitro for sensitivity to the AKT inhibitor AZD5363 and the PI3K beta/delta inhibitor AZD8186. The combination of AZD5363 and AZD8186 with castration was evaluated in vivo in PTEN-negative versus PTEN-positive patient-derived xenografts. Tumors and plasma were collected for biomarker analysis.

Outcome Measurements And Statistical Analysis: In vitro growth inhibition was determined by methylthiazolyldiphenyl-tetrazolium bromide assay. In vivo efficacy was monitored by caliper measurements of subcutaneous tumor volume. PI3K/AKT and AR pathway activity was analyzed by Western blot, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction.

Results And Limitations: AZD5363 and AZD8186 inhibited in vitro growth of 10 of 12 and 7 of 12 PCa cell lines, respectively, with increased sensitivity under androgen depletion. In vivo, AZD5363 and AZD8186 as single agents significantly inhibited growth of PTEN-negative PC346C xenografts compared to placebo by 60% and 66%, respectively. Importantly, combination of either agent with castration resulted in long-lasting tumor regression, which persisted after treatment cessation. Expression of AR-target genes kallikrein-related peptidase 3 (KLK3, also known as PSA); transmembrane protease, serine 2 (TMPRSS2); and FK506 binding protein 5 (FKBP5) was upregulated after PI3K/AKT inhibition. Neither compound inhibited tumor growth in the PTEN-positive PC310 model.

Conclusions: Combination with hormonal therapy improved efficacy of PI3K/AKT-targeted agents in PTEN-negative PCa models. Upregulation of AR-target genes upon PI3K/AKT inhibition suggests a compensatory crosstalk between the PI3K-AR pathways. These data strongly advocate for further clinical evaluation.

Patient Summary: Inactivation of the PTEN gene is a common event promoting prostate cancer (PCa) progression. This preclinical study illustrates the potent anticancer activity of novel PTEN-targeted drugs on PCa models, particularly in combination with hormonal therapy.
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http://dx.doi.org/10.1016/j.eururo.2014.08.053DOI Listing
June 2015

Overcoming endocrine resistance due to reduced PTEN levels in estrogen receptor-positive breast cancer by co-targeting mammalian target of rapamycin, protein kinase B, or mitogen-activated protein kinase kinase.

Breast Cancer Res 2014 Sep 11;16(5):430. Epub 2014 Sep 11.

Introduction: Activation of the phosphatidylinositol 3-kinase (PI3K) pathway in estrogen receptor α (ER)-positive breast cancer is associated with reduced ER expression and activity, luminal B subtype, and poor outcome. Phosphatase and tensin homolog (PTEN), a negative regulator of this pathway, is typically lost in ER-negative breast cancer. We set out to clarify the role of reduced PTEN levels in endocrine resistance, and to explore the combination of newly developed PI3K downstream kinase inhibitors to overcome this resistance.

Methods: Altered cellular signaling, gene expression, and endocrine sensitivity were determined in inducible PTEN-knockdown ER-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer cell and/or xenograft models. Single or two-agent combinations of kinase inhibitors were examined to improve endocrine therapy.

Results: Moderate PTEN reduction was sufficient to enhance PI3K signaling, generate a gene signature associated with the luminal B subtype of breast cancer, and cause endocrine resistance in vitro and in vivo. The mammalian target of rapamycin (mTOR), protein kinase B (AKT), or mitogen-activated protein kinase kinase (MEK) inhibitors, alone or in combination, improved endocrine therapy, but the efficacy varied by PTEN levels, type of endocrine therapy, and the specific inhibitor(s). A single-agent AKT inhibitor combined with fulvestrant conferred superior efficacy in overcoming resistance, inducing apoptosis and tumor regression.

Conclusions: Moderate reduction in PTEN, without complete loss, can activate the PI3K pathway to cause endocrine resistance in ER-positive breast cancer, which can be overcome by combining endocrine therapy with inhibitors of the PI3K pathway. Our data suggests that the ER degrader fulvestrant, to block both ligand-dependent and -independent ER signaling, combined with an AKT inhibitor is an effective strategy to test in patients.
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http://dx.doi.org/10.1186/s13058-014-0430-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303114PMC
September 2014

Combination AZD5363 with Enzalutamide Significantly Delays Enzalutamide-resistant Prostate Cancer in Preclinical Models.

Eur Urol 2015 Jun 20;67(6):986-990. Epub 2014 Aug 20.

The Vancouver Prostate Centre, University of British Columbia, Vancouver, BC, Canada. Electronic address:

Unlabelled: The phosphatidylinositol-4,5-bisphosphate 3-kinase/Akt (PI3K/Akt) pathway is a key pathway activated in castrate-resistant prostate cancer (CRPC). This preclinical study evaluates targeting of Akt with AZD5363 alone and in combination with enzalutamide (ENZ) to prevent and delay resistance. Our results demonstrate AZD5363 has significant proapoptotic, antiproliferative activity as monotherapy in ENZ-resistant cell lines in vitro and significantly decreased tumour growth in ENZ-resistant xenograft. The combination of AZD5363 and ENZ showed synergistic decreases in cell proliferation and induced cell-cycle arrest and apoptosis in prostate cancer cell lines LNCaP and C4-2. Notably, the combination of AZD5363 and ENZ resulted in an impressive regression of castrate-resistant LNCaP xenograft tumours without any recurrence demonstrated, whereas progression occurred with both monotherapies. Serum prostate-specific antigen (PSA) levels were also continuously suppressed, and nadir PSA levels were lower in the combination arm compared to ENZ alone. Combination AZD5363 and ENZ at time of castration similarly resulted in significant regression of tumours, with greater relative suppression of PSA compared to when administered to castrate-resistant xenografts. In summary, combination AZD5363 and ENZ significantly delays the development of ENZ resistance in preclinical models through synergistic increases in apoptosis and cell cycle arrest. Our results also suggest greater efficacy may be seen with earlier combination treatment. This study provides preclinical data to support evaluation of combination targeting of the PI3K/Akt pathway and the androgen-receptor axis in the clinic using AZD5363 and ENZ, respectively.

Patient Summary: Targeting of the Akt and androgen receptor pathways with AZD5363 and enzalutamide, respectively, significantly delayed the development of enzalutamide-resistant prostate cancer through increased apoptosis and cell cycle arrest. This preclinical synergy provides a strong rationale for clinical evaluation of this combination.
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http://dx.doi.org/10.1016/j.eururo.2014.08.006DOI Listing
June 2015