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

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.

Abstract B98: Development and evaluation of selective, reversible LSD1 inhibitors from fragment startpoints

There is currently considerable interest in lysine-specific histone demethylase 1 (LSD1) as a therapeutic target in human malignancies. Specifically LSD1 has been demonstrated to be an essential regulator of leukaemia stem cell potential, inhibiting differentiation and apoptosis in the MLL-AML setting. There are a variety of potent irreversible LSD1 inhibitors available but here we present two series of reversible aminothiazole inhibitors obtained through the expansion of hits derived from a high concentration biochemical screen of a fragment library. The potency of the initial fragment hits was increased 32-fold through synthesis, with one series of compounds showing clear structure activity relationships (SAR) and inhibitory activities in the range of 7 to 187 µM in a biochemical assay. This series also showed selectivity against the homologous amine oxidase enzyme monoamine oxidase A (MAO-A).

This work represents one of the first reported examples of a reversible small molecule inhibitor of LSD1 with clear SAR and selectivity against MAO-A, and could provide a platform for the development of more potent reversible inhibitors. We also report the first Proof of Mechanism (POM) cell based assay utilizing CD86 expression as a surrogate marker of LSD1 activity in THP1 cells and its use to evaluate both our compounds and some recently reported reversible LSD1 inhibitors.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B98.

Citation Format: Alex Stowell, Niall Hamilton, James Hitchin, Julian Blagg, Rosemary Burke, Samantha Burns, Mark J. Cockerill, Emma Fairweather, Colin Hutton, Allan Jordan, Daniel Mould, Graeme Thomson, Ian Waddell, Donald Ogilvie. Development and evaluation of selective, reversible LSD1 inhibitors from fragment startpoints. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B98.

Discovery of AZD8931, an Equipotent, Reversible Inhibitor of Signaling by EGFR, HER2, and HER3 Receptors

Deregulation of HER family signaling promotes proliferation and tumor cell survival and has been described in many human cancers. Simultaneous, equipotent inhibition of EGFR-, HER2-, and HER3-mediated signaling may be of clinical utility in cancer settings where the selective EGFR or HER2 therapeutic agents are ineffective or only modestly active. We describe the discovery of AZD8931 (2), an equipotent, reversible inhibitor of EGFR-, HER2-, and HER3-mediated signaling and the structure-activity relationships within this series. Docking studies based on a model of the HER2 kinase domain helped rationalize the increased HER2 activity seen with the methyl acetamide side chain present in AZD8931. AZD8931 exhibited good pharmacokinetics in preclinical species and showed superior activity in the LoVo tumor growth efficacy model compared to close analogues. AZD8931 is currently being evaluated in human clinical trials for the treatment of cancer.

Abstract 3324: The discovery and optimisation of small-molecule inhibitors of human 5’-tyrosyl DNA phosphodiesterase (Tdp2)

Topoisomerases (topo) regulate DNA topology by the transient cleavage and re-ligation of DNA during transcription and replication. Topo II poisons such as etoposide can induce abortive DNA strand breaks in which topo II remains covalently bound to a 5’ DNA strand terminus via a phosphotyrosyl linker. Tyrosyl DNA phosphodiesterase 2 (Tdp2, TTRAP, EAPII) is a recently discovered human 5’-tyrosyl DNA phosphodiesterase which repairs this topo-mediated DNA damage, therefore playing a central role in maintaining normal DNA topology in cells. Cellular depletion of Tdp2 has been shown to result in an increased susceptibility and sensitivity to topo II-induced DNA double strand breaks. It has therefore been proposed that selective pharmacological inhibition of Tdp2 may be a novel approach to overcome intrinsic or acquired resistance to topo II targeted drug therapy.

To date, no known drug-like inhibitors of Tdp2 have been identified. We have recently reported a robust ‘mix and read’ HTS compatible assay and this was used to screen a diverse chemical library of approximately 92,000 compounds. From this endeavour, 2 distinct hit series have been identified. Following further chemical exploration of the original hit compounds, small molecule inhibitors of Tdp2 with sub-100nM potencies have been identified. This poster will describe our biological and chemical progress in this area, detailing SAR and some lessons learnt during investigation of this target.

Citation Format: Allan M. Jordan, Paul Depledge, Nicola Hamilton, James Hitchin, Gemma Hopkins, Laura Maguire, Alison McGonagle, Daniel Mould, Ali Raoof, Mathew Rushbrooke, James Smith, Kate Smilth, Graeme Thomson, Fabrice Turlais, Ian Waddell, Mandy Watson, Donald Ogilvie. The discovery and optimisation of small-molecule inhibitors of human 5’-tyrosyl DNA phosphodiesterase (Tdp2). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3324. doi:10.1158/1538-7445.AM2013-3324

Generation of assays and antibodies to facilitate the study of human 5'-tyrosyl DNA phosphodiesterase

Topoisomerases regulate DNA topology by the transient cleavage and religation of DNA during transcription and replication. Topoisomerase II (Topo II) poisons such as etoposide can induce abortive DNA strand breaks in which Topo II remains covalently bound to a 5' DNA strand terminus via a phosphotyrosyl linker. Tyrosyl DNA phosphodiesterase 2 (Tdp2) is a recently discovered human 5'-tyrosyl DNA phosphodiesterase that repairs this topoisomerase-mediated DNA damage, thereby playing a central role in maintaining normal DNA topology in cells. Cellular depletion of Tdp2 has been shown to result in increased susceptibility and sensitivity to Topo II-induced DNA double-strand breaks, thereby revealing Tdp2 as a potentially attractive anticancer target. No drug-like inhibitors of Tdp2 have been identified to date, and assays suitable for high-throughput screening (HTS) have not been widely reported. Here we have identified a new and effective chromogenic substrate for Tdp2 and developed a homogeneous and robust HTS assay. A second novel Tdp2 assay was also developed to cross-validate hit matter identified from an HTS. In addition, a new and specific Tdp2 antibody is described. Together, these new tools will aid in the identification of novel Tdp2 inhibitors and the investigation of the role of Tdp2 in cancer.

Towards a differentiated understanding of active travel behaviour: using social theory to explore everyday commuting

Fostering physical activity is an established public health priority for the primary prevention of a variety of chronic diseases. One promising population approach is to seek to embed physical activity in everyday lives by promoting walking and cycling to and from work (‘active commuting’) as an alternative to driving. Predominantly quantitative epidemiological studies have investigated travel behaviours, their determinants and how they may be changed towards more active choices. This study aimed to depart from narrow behavioural approaches to travel and investigate the social context of commuting with qualitative social research methods. Within a social practice theory framework, we explored how people describe their commuting experiences and make commuting decisions, and how travel behaviour is embedded in and shaped by commuters' complex social worlds. Forty-nine semi-structured interviews and eighteen photo-elicitation interviews with accompanying field notes were conducted with a subset of the Commuting and Health in Cambridge study cohort, based in the UK. The findings are discussed in terms of three particularly pertinent facets of the commuting experience. Firstly, choice and decisions are shaped by the constantly changing and fluid nature of commuters' social worlds. Secondly, participants express ambiguities in relation to their reasoning, ambitions and identities as commuters. Finally, commuting needs to be understood as an embodied and emotional practice. With this in mind, we suggest that everyday decision-making in commuting requires the tactical negotiation of these complexities. This study can help to explain the limitations of more quantitative and static models and frameworks in predicting travel behaviour and identify future research directions.

A community prevention model to prevent children from inhaling and ingesting harmful legal products

Children's misuse of harmful legal products (HLPs), including inhaling or ingesting everyday household products, prescription drugs, and over-the-counter drugs, constitutes a serious health problem for American society. This article presents a community prevention model (CPM) focusing on this problem among pre and early adolescents. The model, consisting of a community mobilization strategy and environmental strategies targeting homes, schools, and retail outlets, is designed to increase community readiness and reduce the availability of HLPs, which is hypothesized to reduce HLPs use among children. The CPM is being tested in Alaskan rural communities as part of an inprogress eight-year National Institute on Drug Abuse randomized-controlled trial. This paper presents the CPM conceptual framework, describes the model, and highlights community participation, challenges, and lessons learned from implementation of the model over a 21-month period.

Preclinical pharmacology of AZD5363, an inhibitor of AKT: pharmacodynamics, antitumor activity, and correlation of monotherapy activity with genetic background

AKT is a key node in the most frequently deregulated signaling network in human cancer. AZD5363, a novel pyrrolopyrimidine-derived compound, inhibited all AKT isoforms with a potency of 10 nmol/L or less and inhibited phosphorylation of AKT substrates in cells with a potency of approximately 0.3 to 0.8 μmol/L. AZD5363 monotherapy inhibited the proliferation of 41 of 182 solid and hematologic tumor cell lines with a potency of 3 μmol/L or less. Cell lines derived from breast cancers showed the highest frequency of sensitivity. There was a significant relationship between the presence of PIK3CA and/or PTEN mutations and sensitivity to AZD5363 and between RAS mutations and resistance. Oral dosing of AZD5363 to nude mice caused dose- and time-dependent reduction of PRAS40, GSK3β, and S6 phosphorylation in BT474c xenografts (PRAS40 phosphorylation EC(50) ~ 0.1 μmol/L total plasma exposure), reversible increases in blood glucose concentrations, and dose-dependent decreases in 2[18F]fluoro-2-deoxy-D-glucose ((18)F-FDG) uptake in U87-MG xenografts. Chronic oral dosing of AZD5363 caused dose-dependent growth inhibition of xenografts derived from various tumor types, including HER2(+) breast cancer models that are resistant to trastuzumab. AZD5363 also significantly enhanced the antitumor activity of docetaxel, lapatinib, and trastuzumab in breast cancer xenografts. It is concluded that AZD5363 is a potent inhibitor of AKT with pharmacodynamic activity in vivo, has potential to treat a range of solid and hematologic tumors as monotherapy or a combinatorial agent, and has potential for personalized medicine based on the genetic status of PIK3CA, PTEN, and RAS. AZD5363 is currently in phase I clinical trials.

AZD8931, an equipotent, reversible inhibitor of signaling by epidermal growth factor receptor, ERBB2 (HER2), and ERBB3: a unique agent for simultaneous ERBB receptor blockade in cancer

PURPOSE

To test the hypothesis that simultaneous, equipotent inhibition of epidermal growth factor receptor (EGFR; erbB1), erbB2 (human epidermal growth factor receptor 2), and erbB3 receptor signaling, using the novel small-molecule inhibitor AZD8931, will deliver broad antitumor activity in vitro and in vivo.

EXPERIMENTAL DESIGN

A range of assays was used to model erbB family receptor signaling in homodimers and heterodimers, including in vitro evaluation of erbB kinase activity, erbB receptor phosphorylation, proliferation in cells, and in vivo testing in a human tumor xenograft panel, with ex vivo evaluation of erbB phosphorylation and downstream biomarkers. Gefitinib and lapatinib were used to compare the pharmacological profile of AZD8931 with other erbB family inhibitors.

RESULTS

In vitro, AZD8931 showed equipotent, reversible inhibition of EGFR (IC(50), 4 nmol/L), erbB2 (IC(50), 3 nmol/L), and erbB3 (IC(50), 4 nmol/L) phosphorylation in cells. In proliferation assays, AZD8931 was significantly more potent than gefitinib or lapatinib in specific squamous cell carcinoma of the head and neck and non-small cell lung carcinoma cell lines. In vivo, AZD8931 inhibited xenograft growth in a range of models while significantly affecting EGFR, erbB2, and erbB3 phosphorylation and downstream signaling pathways, apoptosis, and proliferation.

CONCLUSIONS

AZD8931 has a unique pharmacologic profile providing equipotent inhibition of EGFR, erbB2, and erbB3 signaling and showing greater antitumor activity than agents with a narrower spectrum of erbB receptor inhibition in specific preclinical models. AZD8931 provides the opportunity to investigate whether simultaneous inhibition of erbB receptor signaling could be of utility in the clinic, particularly in the majority of solid tumors that do not overexpress erbB2.

Evaluation of AZD8931, an Equipotent Inhibitor of erbB1, erbB2, and erbB3 Receptor Signaling, on Ligand Stimulated Breast Cancer Cell Lines with Differing Levels of erbB2 Expression

Background: Further treatment options for patients whose breast cancers do not overexpress erbB2 are required. AZD8931, an equipotent, reversible inhibitor of erbB1 (HER1, EGFR), erbB2 (HER2), and erbB3 (HER3) receptor signaling may be useful in this setting and may lead to inhibition of tumor cell proliferation, invasion, metastasis, angiogenesis and tumor cell survival.Objectives: To compare the activity of AZD8931 with other erbB inhibitors (gefitinib [G] and lapatinib [L]) in breast cancer cell lines stimulated with erbB ligands.Methods: A panel of 9 breast cancer cell lines with differing erbB2 expression levels were used: erbB2+/ER+ (BT474c; MDA-MB-361); erbB2+/ER- (MDA-MB-453; SKBR-3); erbB2-/ER+ (MCF7; T47D; ZR75-1); or erbB2-/ER- (MDA-MB-231; MDA-MB-468). Following overnight serum starvation, cells were incubated with AZD8931, G or L (0-10 µM) for 90 min and then stimulated with erbB ligands (50 ng/ml; EGF, TGFα, amphiregulin, epiregulin, betacellulin, neuregulin1, or HBEGF) for 5 min before lysis. Levels of phosphorylated erbB1, erbB2, and erbB3 were analyzed by ELISA. For IC50 determination, mean basal phosphorylation was subtracted. Geometric mean IC50s were calculated from triplicate assays and 2-sided unequal variance t-tests compared logIC50s.Results: AZD8931 demonstrated potent inhibitory activity (IC50s ≤10610 nM) when phosphorylation of erbB1, erbB2 or erbB3 receptors was driven by any erbB ligand. G demonstrated potent inhibitory activity (IC50s ≤20 nM) when the phosphorylation of erbB1 and erbB2 was driven by any erbB ligand. L more strongly inhibited the phosphorylation of erbB2 (IC50s ≤10 nM) than erbB1 (IC50s &lt;400 nM) and showed a ligand and cell-dependant range of activities against erbB3 phosphorylation. AZD8931 was particularly differentiated from G and L in the inhibition of neuregulin1-driven erbB3 phosphorylation: IC50s were lower for AZD8931 (1-5 nM) than for G (1-120 nM) or L (20-80 nM) in the majority of the cell lines tested. Inhibition of erbB1 phosphorylation driven by EGF (IC50s ≤ vs &gt;20 nM), TGFα (≤5 vs &gt;20 nM), HB-EGF (≤ vs &gt;25 nM), or betacellulin (≤6 vs 10-118 nM) also indicated more potent inhibitory activity for AZD8931 over L in cell lines that respond to ligand stimulation. No phosphorylation response to amphiregulin was seen in any of the cell lines.Conclusion: This study demonstrates that in a range of breast cell lines with varying levels of erbB2 expression, AZD8931 is a potent and balanced inhibitor of erbB1, erbB2, and erbB3 signaling. The pharmacological profile of AZD8931 is thus distinct from G and L and suggests that AZD8931 offers an agent to test the hypothesis that combined, balanced inhibition of erbB signaling could provide clinical benefit. AZD8931 may be particularly useful in the treatment of solid tumors that do not overexpress erbB2 including trastuzumab-ineligible breast cancer, an area of unmet medical need. AZD8931 is being evaluated in a Phase I clinical trial.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5059.