Mandy Lawson

Characterization of a selective and potent antagonist of human P2X7 receptors, AZ11645373

The ATP‐gated P2X7 receptor has been shown to play a role in several inflammatory processes, making it an attractive target for anti‐inflammatory drug discovery. We have recently identified a novel set of cyclic imide compounds that inhibited P2X7 receptor‐mediated dye uptake in human macrophage THP‐1 cells. In this study the actions and selectivity of one of these compounds, AZ11645373, were characterized.

AZD9496: An Oral Estrogen Receptor Inhibitor That Blocks the Growth of ER-Positive and ESR1-Mutant Breast Tumors in Preclinical Models.

Fulvestrant is an estrogen receptor (ER) antagonist administered to breast cancer patients by monthly intramuscular injection. Given its present limitations of dosing and route of administration, a more flexible orally available compound has been sought to pursue the potential benefits of this drug in patients with advanced metastatic disease. Here we report the identification and characterization of AZD9496, a nonsteroidal small-molecule inhibitor of ERα, which is a potent and selective antagonist and downregulator of ERα in vitro and in vivo in ER-positive models of breast cancer. Significant tumor growth inhibition was observed as low as 0.5 mg/kg dose in the estrogen-dependent MCF-7 xenograft model, where this effect was accompanied by a dose-dependent decrease in PR protein levels, demonstrating potent antagonist activity. Combining AZD9496 with PI3K pathway and CDK4/6 inhibitors led to further growth-inhibitory effects compared with monotherapy alone. Tumor regressions were also seen in a long-term estrogen-deprived breast model, where significant downregulation of ERα protein was observed. AZD9496 bound and downregulated clinically relevant ESR1 mutants in vitro and inhibited tumor growth in an ESR1-mutant patient-derived xenograft model that included a D538G mutation. Collectively, the pharmacologic evidence showed that AZD9496 is an oral, nonsteroidal, selective estrogen receptor antagonist and downregulator in ER(+) breast cells that could provide meaningful benefit to ER(+) breast cancer patients. AZD9496 is currently being evaluated in a phase I clinical trial. Cancer Res; 76(11); 3307-18. ©2016 AACR.

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. Mol Cancer Ther; 14(1); 48–58. ©2014 AACR.

Agonist-specific patterns of beta(2)-adrenoceptor responses in human airway cells during prolonged exposure.

Background and purpose:  β2‐Adrenoceptor agonists (β2‐agonists) are important bronchodilators used in the treatment of asthma and chronic obstructive pulmonary disease. At the molecular level, β2‐adrenergic agonist stimulation induces desensitization of the β2‐adrenoceptor. In this study, we have examined the relationships between initial effect and subsequent reduction of responsiveness to restimulation for a panel of β2‐agonists in cellular and in vitro tissue models.

Design driven HtL: The discovery and synthesis of new high efficacy β2-agonists

The design and synthesis of a new series of high efficacy β(2)-agonists devoid of the key benzylic alcohol present in previously described highly efficacious β(2)-agonists is reported. A hypothesis for the unprecedented level of efficacy is proposed based on considerations of β(2)-adrenoceptor crystal structure, other biophysical data and modeling studies.

From libraries to candidate: The discovery of new ultra long-acting dibasic β2-adrenoceptor agonists

Libraries of dibasic compounds designed around the molecular scaffold of the DA(2)/β(2) dual agonist sibenadet (Viozan™) have yielded a number of promising starting points that have been further optimised into novel potent and selective target molecules with required pharmacokinetic properties. From a shortlist, 31 was discovered as a novel, high potency, and highly efficacious β(2)-agonist with high selectivity and a duration of action commensurable with once daily dosing.

Discovery of AZD3199, An Inhaled Ultralong Acting β2 Receptor Agonist with Rapid Onset of Action.

A series of dibasic des-hydroxy β2 receptor agonists has been prepared and evaluated for potential as inhaled ultralong acting bronchodilators. Determination of activities at the human β-adrenoreceptors demonstrated a series of highly potent and selective β2 receptor agonists that were progressed to further study in a guinea pig histamine-induced bronchoconstriction model. Following further assessment by onset studies in guinea pig tracheal rings and human bronchial rings contracted with methacholine (guinea pigs) or carbachol (humans), duration of action studies in guinea pigs after intratracheal (i.t.) administration and further selectivity and safety profiling AZD3199 was shown to have an excellent over all profile and was progressed into clinical evaluation as a new ultralong acting inhaled β2 receptor agonist with rapid onset of action.

Combined inhibition of mTOR and CDK4/6 is required for optimal blockade of E2F function and long term growth inhibition in estrogen receptor positive breast cancer

The cyclin dependent kinase (CDK)–retinoblastoma (RB)–E2F pathway plays a critical role in the control of cell cycle in estrogen receptor–positive (ER+) breast cancer. Small-molecule inhibitors of CDK4/6 have shown promise in this tumor type in combination with hormonal therapies, reflecting the particular dependence of this subtype of cancer on cyclin D1 and E2F transcription factors. mTOR inhibitors have also shown potential in clinical trials in this disease setting. Recent data have suggested cooperation between the PI3K/mTOR pathway and CDK4/6 inhibition in preventing early adaptation and eliciting growth arrest, but the mechanisms of the interplay between these pathways have not been fully elucidated. Here we show that profound and durable inhibition of ER+ breast cancer growth is likely to require multiple hits on E2F-mediated transcription. We demonstrate that inhibition of mTORC1/2 does not affect ER function directly, but does cause a decrease in cyclin D1 protein, RB phosphorylation, and E2F-mediated transcription. Combination of an mTORC1/2 inhibitor with a CDK4/6 inhibitor results in more profound effects on E2F-dependent transcription, which translates into more durable growth arrest and a delay in the onset of resistance. Combined inhibition of mTORC1/2, CDK4/6, and ER delivers even more profound and durable regressions in breast cancer cell lines and xenografts. Furthermore, we show that CDK4/6 inhibitor–resistant cell lines reactivate the CDK–RB–E2F pathway, but remain sensitive to mTORC1/2 inhibition, suggesting that mTORC1/2 inhibitors may represent an option for patients that have relapsed on CDK4/6 therapy. Mol Cancer Ther; 17(5); 908–20. ©2018 AACR.

Abstract 3264: AZD8186: a potent selective inhibitor of PI3Kβ targeting PTEN-deficient tumours dependent on dysregulated PI3Kβ signalling.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC AZD8186 is a novel potent small molecule that targets the lipid kinase PI3Kβ with selectivity vs PI3Kα. AZD8186 reduces pAKT-S473 in the PTEN deficient MDA-MB-468 cell line with an IC50 <5nM, while in the PI3Kα-dependent PIK3CA mutant line BT474 it is 200 fold less potent. AZD8186 also demonstrates cellular activity versus PI3Kβ, inhibiting IgM-dependent pAKT-S473 with an IC50 of 15nM. In cell line panels, sensitivity to AZD8186 is associated in part with loss of PTEN function suggesting that targeting tumours that have lost normal levels of PTEN function through deletion, mutation or down regulation might enrich for sensitivity to AZD8186. Deficiencies in PTEN are described in a number of tumour types such as prostate, squamous lung, breast, renal and glioblastoma. AZD8186 has single anti-tumour activity in pre-clinical models representing each of these settings, which is associated with dynamic regulation of a number of key pathway biomarkers. Clinically, agents such as AZD8186 are likely to be used in combination. The use of AZD8186 in conjunction with either androgen therapy or docetaxol has been explored in cell lines and pre-clinical disease models. Combining AZD8186 with MDV-3100 resulted in synergistic inhibition of LNCAP prostate tumour cell growth, demonstrating the potential to combine with androgen therapy. Moreover in HCC70 (breast) and PC3 (prostate) tumour xenografts AZD8186 shows increased benefit in combination with docetaxel, demonstrating the ability to combine with cytotoxic chemotherapy. Exploration of dose and schedule revealed that efficacy can be maintained in combination with docetaxol at a lower dose of AZD8186 than required for monotherapy activity. Moreover efficacy was maintained when the frequency of AZD8186 dosing was reduced using a shorter intermittent schedule. Understanding how AZD8186 combines with standards of care for PTEN null disease segments provides important insight into how agents targeting PI3Kβ-dependent tumours may be used most effectively in the clinic. [Current affiliation for S. Cosulich is Novartis, Basel, Switzerland.] Citation Format: Urs Hancox, Sabina Cosulich, Hannah Dry, Lynsey Hanson, Clare Crafter, Bernard Barlaam, Martina Fitzek, Lara Ward, Marie Cumberbatch, Steve Powell, Rebecca Ellston, Mandy Lawson, Steve Wedge, Liz Harrington, Stephen Green, Simon T. Barry. AZD8186: a potent selective inhibitor of PI3Kβ targeting PTEN-deficient tumours dependent on dysregulated PI3Kβ signalling. [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 3264. doi:10.1158/1538-7445.AM2013-3264

Abstract DDT01-03: Discovery and pre-clinical pharmacology of AZD9496: An oral, selective estrogen receptor down-regulator (SERD)

With over 70% of breast cancers expressing estrogen receptor alpha protein (ERα), treatment with either anti-hormonal therapies that directly block ERα function (e.g. tamoxifen) or therapies that block the production of estrogen itself (e.g. anastrozole) have proven to be effective treatments for the disease. Following the discovery of the ERα antagonist tamoxifen in the 1960s, identification of the selective estrogen receptor down-regulator (SERD) fulvestrant represented a further step forward in the treatment of advanced ER+ breast cancer, especially in the endocrine resistance setting where ERα appears to be activated by a ligand independent route through other growth factor signaling pathways. In addition, fulvestrant has also shown significant overall survival (OS) results in the FIRST trial comparing 500 mg fulvestrant with anastrozole in first line advanced ER+ve patients where the majority of patients had not received prior endocrine therapy. Given fulvestrant9s low bioavailability following intramuscular injection and the levels of ERα protein in clinical samples after treatment, the question remains as to whether an agent that could achieve higher steady state levels of drug more rapidly and drive further decreases in ERα levels would give enhanced clinical benefit. We have identified a novel, potent, non-steroidal SERD that can be administered orally and could yield improved exposure and clinical benefit. This presentation will describe the discovery and pre-clinical pharmacology of AZD9496, a small molecule that can antagonise ERα and induce receptor degradation in breast cancer cell lines at picomolar concentrations. The good oral pharmacokinetic properties of the compound in pre-clinical species led to significant tumor growth inhibition in an endocrine sensitive MCF-7 xenograft model at a dose of 5 mg/kg and >90% reduction in ER-regulated, progesterone receptor (PR) levels. Tumor regressions were seen in a long term estrogen deprived (LTED) in vivo model, representing the aromatase resistant setting, and corresponded with significant reductions in ERα protein levels, >90% at 5 mg/kg dose. AZD9496 also showed antagonist and down-regulation activity against ERα mutant protein both in vitro and in vivo. These findings strongly supported selection of AZD9496 as a clinical candidate for the treatment of ER+ve breast cancer and the drug is now under evaluation in a Phase 1 clinical trial. Citation Format: Hazel Weir, Mandy Lawson, Rowena Callis, Michael Hulse, Michael Tonge, Gareth Davies, Graeme Walker, Rachel Rowlinson, Jon Curwen, Zena Wilson, Steve Powell, Robert Bradbury, Alfred Rabow, Craig Donald, David Buttar, Richard Norman, Camila de Almeida, Peter Ballard, Gordon Currie, David Andrews, Graham Richmond, Anne Marie Mazzola, Ermira Pazolli, Brendon Ladd, Celina D9Cruz, Chris De Savi. Discovery and pre-clinical pharmacology of AZD9496: An oral, selective estrogen receptor down-regulator (SERD). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr DDT01-03. doi:10.1158/1538-7445.AM2015-DDT01-03