Identification of Novel, Selective Ataxia-Telangiectasia Mutated Kinase Inhibitors with the Ability to Penetrate the Blood-Brain Barrier: The Discovery of AZD1390

The inhibition of ataxia-telangiectasia mutated (ATM) has been shown to chemo- and radio-sensitize human glioma cells in vitro and therefore might provide an exciting new paradigm in the treatment of glioblastoma multiforme (GBM). The effective treatment of GBM will likely require a compound with the potential to efficiently cross the blood-brain barrier (BBB). Starting from clinical candidate AZD0156, 4, we investigated the imidazoquinolin-2-one scaffold with the goal of improving likely CNS exposure in humans. Strategies aimed at reducing hydrogen bonding, basicity, and flexibility of the molecule were explored alongside modulating lipophilicity. These studies identified compound 24 (AZD1390) as an exceptionally potent and selective inhibitor of ATM with a good preclinical pharmacokinetic profile. 24 showed an absence of human transporter efflux in MDCKII-MDR1-BCRP studies (efflux ratio <2), significant BBB penetrance in nonhuman primate PET studies (Kp,uu 0.33) and was deemed suitable for development as a clinical candidate to explore the radiosensitizing effects of ATM in intracranial malignancies.

Identification and optimization of a novel series of selective PIP5K inhibitors

Phosphatidyl inositol (4,5)-bisphosphate (PI(4,5)P₂) plays several key roles in human biology and the lipid kinase that produces PI(4,5)P₂, PIP5K, has been hypothesized to provide a potential therapeutic target of interest in the treatment of cancers. To better understand and explore the role of PIP5K in human cancers there remains an urgent need for potent and specific PIP5K inhibitor molecules. Following a high throughput screen of the AstraZeneca collection, a novel, moderately potent and selective inhibitor of PIP5K, 1, was discovered. Detailed exploration of the SAR for this novel scaffold resulted in the considerable optimization of both potency for PIP5K, and selectivity over the closely related kinase PI3Kα, as well as identifying several opportunities for the continued optimization of drug-like properties. As a result, several high quality in vitro tool compounds were identified (8, 20 and 25) that demonstrate the desired biochemical and cellular profiles required to aid better understanding of this complex area of biology.

Diverse, Potent, and Efficacious Inhibitors That Target the EED Subunit of the Polycomb Repressive Complex 2 Methyltransferase

Aberrant activity of the histone methyltransferase polycomb repressive complex 2 (PRC2) has been linked to several cancers, with small-molecule inhibitors of the catalytic subunit of the PRC2 enhancer of zeste homologue 2 (EZH2) being recently approved for the treatment of epithelioid sarcoma (ES) and follicular lymphoma (FL). Compounds binding to the EED subunit of PRC2 have recently emerged as allosteric inhibitors of PRC2 methyltransferase activity. In contrast to orthosteric inhibitors that target EZH2, small molecules that bind to EED retain their efficacy in EZH2 inhibitor-resistant cell lines. In this paper we disclose the discovery of potent and orally bioavailable EED ligands with good solubilities. The solubility of the EED ligands was optimized through a variety of design tactics, with the resulting compounds exhibiting in vivo efficacy in EZH2-driven tumors.

Discovery of a Series of 7-Azaindoles as Potent and Highly Selective CDK9 Inhibitors for Transient Target Engagement

Optimization of a series of azabenzimidazoles identified from screening hit 2 and the information gained from a co-crystal structure of the azabenzimidazole-based lead 6 bound to CDK9 led to the discovery of azaindoles as highly potent and selective CDK9 inhibitors. With the goal of discovering a highly selective and potent CDK9 inhibitor administrated intravenously that would enable transient target engagement of CDK9 for the treatment of hematological malignancies, further optimization focusing on physicochemical and pharmacokinetic properties led to azaindoles 38 and 39. These compounds are highly potent and selective CDK9 inhibitors having short half-lives in rodents, suitable physical properties for intravenous administration, and the potential to achieve profound but transient inhibition of CDK9 in vivo.

Discovery of AZD4573, a Potent and Selective Inhibitor of CDK9 That Enables Short Duration of Target Engagement for the Treatment of Hematological Malignancies

A CDK9 inhibitor having short target engagement would enable a reduction of Mcl-1 activity, resulting in apoptosis in cancer cells dependent on Mcl-1 for survival. We report the optimization of a series of amidopyridines (from compound 2), focusing on properties suitable for achieving short target engagement after intravenous administration. By increasing potency and human metabolic clearance, we identified compound 24, a potent and selective CDK9 inhibitor with suitable predicted human pharmacokinetic properties to deliver transient inhibition of CDK9. Furthermore, the solubility of 24 was considered adequate to allow i.v. formulation at the anticipated effective dose. Short-term treatment with compound 24 led to a rapid dose- and time-dependent decrease of pSer2-RNAP2 and Mcl-1, resulting in cell apoptosis in multiple hematological cancer cell lines. Intermittent dosing of compound 24 demonstrated efficacy in xenograft models derived from multiple hematological tumors. Compound 24 is currently in clinical trials for the treatment of hematological malignancies.

Pharmacology of the ATM Inhibitor AZD0156: Potentiation of Irradiation and Olaparib Responses Preclinically

AZD0156 is a potent and selective, bioavailable inhibitor of ataxia-telangiectasia mutated (ATM) protein, a signaling kinase involved in the DNA damage response. We present preclinical data demonstrating abrogation of irradiation-induced ATM signaling by low doses of AZD0156, as measured by phosphorylation of ATM substrates. AZD0156 is a strong radiosensitizer in vitro, and using a lung xenograft model, we show that systemic delivery of AZD0156 enhances the tumor growth inhibitory effects of radiation treatment in vivo Because ATM deficiency contributes to PARP inhibitor sensitivity, preclinically, we evaluated the effect of combining AZD0156 with the PARP inhibitor olaparib. Using ATM isogenic FaDu cells, we demonstrate that AZD0156 impedes the repair of olaparib-induced DNA damage, resulting in elevated DNA double-strand break signaling, cell-cycle arrest, and apoptosis. Preclinically, AZD0156 potentiated the effects of olaparib across a panel of lung, gastric, and breast cancer cell lines in vitro, and improved the efficacy of olaparib in two patient-derived triple-negative breast cancer xenograft models. AZD0156 is currently being evaluated in phase I studies (NCT02588105).

Discovery of a Series of 3-Cinnoline Carboxamides as Orally Bioavailable, Highly Potent, and Selective ATM Inhibitors

We report the discovery of a novel series of 3-cinnoline carboxamides as highly potent and selective ataxia telangiectasia mutated (ATM) kinase inhibitors. Optimization of this series focusing on potency and physicochemical properties (especially permeability) led to the identification of compound 21, a highly potent ATM inhibitor (ATM cell IC₅₀ 0.0028 μM) with excellent kinase selectivity and favorable physicochemical and pharmacokinetics properties. In vivo, 21 in combination with irinotecan showed tumor regression in the SW620 colorectal tumor xenograft model, superior inhibition to irinotecan alone. Compound 21 was selected for preclinical evaluation alongside AZD0156.

The brain-penetrant clinical ATM inhibitor AZD1390 radiosensitizes and improves survival of preclinical brain tumor models

Poor survival rates of patients with tumors arising from or disseminating into the brain are attributed to an inability to excise all tumor tissue (if operable), a lack of blood-brain barrier (BBB) penetration of chemotherapies/targeted agents, and an intrinsic tumor radio-/chemo-resistance. Ataxia-telangiectasia mutated (ATM) protein orchestrates the cellular DNA damage response (DDR) to cytotoxic DNA double-strand breaks induced by ionizing radiation (IR). ATM genetic ablation or pharmacological inhibition results in tumor cell hypersensitivity to IR. We report the primary pharmacology of the clinical-grade, exquisitely potent (cell IC₅₀, 0.78 nM), highly selective [>10,000-fold over kinases within the same phosphatidylinositol 3-kinase-related kinase (PIKK) family], orally bioavailable ATM inhibitor AZD1390 specifically optimized for BBB penetration confirmed in cynomolgus monkey brain positron emission tomography (PET) imaging of microdosed ¹¹C-labeled AZD1390 (K_p,uu, 0.33). AZD1390 blocks ATM-dependent DDR pathway activity and combines with radiation to induce G₂ cell cycle phase accumulation, micronuclei, and apoptosis. AZD1390 radiosensitizes glioma and lung cancer cell lines, with p53 mutant glioma cells generally being more radiosensitized than wild type. In in vivo syngeneic and patient-derived glioma as well as orthotopic lung-brain metastatic models, AZD1390 dosed in combination with daily fractions of IR (whole-brain or stereotactic radiotherapy) significantly induced tumor regressions and increased animal survival compared to IR treatment alone. We established a pharmacokinetic-pharmacodynamic-efficacy relationship by correlating free brain concentrations, tumor phospho-ATM/phospho-Rad50 inhibition, apoptotic biomarker (cleaved caspase-3) induction, tumor regression, and survival. On the basis of the data presented here, AZD1390 is now in early clinical development for use as a radiosensitizer in central nervous system malignancies.

Orally Bioavailable and Blood-Brain Barrier-Penetrating ATM Inhibitor (AZ32) Radiosensitizes Intracranial Gliomas in Mice

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.

Abstract A124: Discovery of the clinical candidate AZD1390: a high-quality, potent, and selective inhibitor of ATM kinase with the ability to cross the blood-brain barrier

Glioblastoma multiforme (GBM) is the most common and lethal form of primary brain tumor, and current treatment (surgery followed by fractionated radiotherapy and temozolomide) provides a median survival of just 12-15 months (1,2). The poor prognosis associated with GBM is attributed to an extensive infiltration into surrounding brain tissue (thereby limiting the effectiveness of surgical excision), an intrinsic chemo/radioresistance of the tumor, and the presence of the blood-brain barrier (BBB), which limits the ability of certain chemotherapies to reach the tumor. Ataxia telangiectasia mutant (ATM) is a serine/threonine protein kinase from the phosphatidylinositol 3-kinase-related kinase (PIKK) family of protein kinases and plays a crucial role in the cellular DNA damage response signalling activated by DNA double-strand breaks (DSB). Activated ATM promotes DNA repair and S/G1-cell cycle checkpoints to prevent premature mitosis, maintain genomic integrity, and promote appropriate cell survival or death pathways. DSBs arise intrinsically through the collapse of stalled replication forks, which are induced by a wide range of chemotherapies, or extrinsically through exposure to ionizing radiation. Therefore, ATM inhibition represents an exciting clinical opportunity as a target to hyper-sensitize tumors to chemo/radiotherapy. The optimization of compound properties suitable to allow efficient BBB penetration remains a significant challenge within Medicinal Chemistry, and failure to consider these can severely restrict the utility of an agent for CNS disease. Herein, we describe the identification of AZD1390, a first-in-class orally available and CNS penetrant ATM inhibitor suitable for the treatment of intracranial malignancies. This presentation represents the first disclosure of the Medicinal Chemistry strategies employed to optimize BBB penetration, alongside the SAR for ATM potency, selectivity, and pharmacokinetic properties. AZD1390 is an exceptionally potent inhibitor of ATM in cells (IC50 = 0.78 nM) with &gt;10,000-fold selectivity over closely related members of the PIKK family of enzymes and excellent selectivity across a broad panel of kinases. AZD1390 displays excellent oral bioavailability in preclinical species (66% in rat and 74% in dog), is not a substrate for human efflux transporters, and has been shown to efficiently cross the BBB in non-human primate PET studies. Profound tumor regressions and increased animal survival (&gt;50 days) have been observed in orthotopic xenograft models of brain cancer following just 2 or 4 days combination treatment of AZD1390 with radiotherapy, compared to radiotherapy treatment alone. These data support the potential of CNS-penetrant ATM inhibitors to provide an important new therapeutic agent for the treatment of intracranial malignancies. AZD1390 is currently undergoing early clinical assessment. References: (1) Stupp R, Hegi ME, Gilbert MR, Chakravarti A. Chemoradiotherapy in malignant glioma: standard of care and future directions, J Clin Oncol 2007;25:4127-36. (2) Ajaz M, Jefferies S, Brazil L, Watts C, Chalmers A. Current and investigational drug strategies for glioblastoma. Clin Oncol 2014;26:419-30.

Citation Format: Kurt G. Pike. Discovery of the clinical candidate AZD1390: a high-quality, potent, and selective inhibitor of ATM kinase with the ability to cross the blood-brain barrier [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 A124.

Abstract A104: 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

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 &gt;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.

Targeting the kinase activities of ATR and ATM exhibits antitumoral activity in mouse models of MLL-rearranged AML

Among the various subtypes of acute myeloid leukemia (AML), those with chromosomal rearrangements of the MLL oncogene (AML-MLL) have a poor prognosis. AML-MLL tumor cells are resistant to current genotoxic therapies because of an attenuated response by p53, a protein that induces cell cycle arrest and apoptosis in response to DNA damage. In addition to chemicals that damage DNA, efforts have focused on targeting DNA repair enzymes as a general chemotherapeutic approach to cancer treatment. Here, we found that inhibition of the kinase ATR, which is the primary sensor of DNA replication stress, induced chromosomal breakage and death of mouse AML(MLL) cells (with an MLL-ENL fusion and a constitutively active N-RAS independently of p53. Moreover, ATR inhibition as a single agent exhibited antitumoral activity, both reducing tumor burden after establishment and preventing tumors from growing, in an immunocompetent allograft mouse model of AML(MLL) and in xenografts of a human AML-MLL cell line. We also found that inhibition of ATM, a kinase that senses DNA double-strand breaks, also promoted the survival of the AML(MLL) mice. Collectively, these data indicated that ATR or ATM inhibition represent potential therapeutic strategies for the treatment of AML, especially MLL-driven leukemias.

Discovery of 4,6-disubstituted pyrimidines as potent inhibitors of the heat shock factor 1 (HSF1) stress pathway and CDK9

Heat shock factor 1 (HSF1) is a transcription factor that plays key roles in cancer, including providing a mechanism for cell survival under proteotoxic stress. Therefore, inhibition of the HSF1-stress pathway represents an exciting new opportunity in cancer treatment. We employed an unbiased phenotypic screen to discover inhibitors of the HSF1-stress pathway. Using this approach we identified an initial hit (1) based on a 4,6-pyrimidine scaffold (2.00 μM). Optimisation of cellular SAR led to an inhibitor with improved potency (25, 15 nM) in the HSF1 phenotypic assay. The 4,6-pyrimidine 25 was also shown to have high potency against the CDK9 enzyme (3 nM).

Abstract 4859: Identifying high quality, potent and selective inhibitors of ATM kinase: Discovery of AZD0156

Ataxia telangiectasia mutant (ATM) is a serine/threonine protein kinase from the phosphatidylinositol 3-kinase-related kinase (PIKK) family of protein kinases (also comprising ATR, DNA-PKcs, mTOR etc.) and plays a crucial role in the cellular DNA damage response signalling activated by DNA double strand breaks (DSB). Activated ATM promotes DNA repair and S/G1-cell cycle checkpoints to prevent premature mitosis, maintain genomic integrity and promote appropriate cell survival or death pathways. DSBs arise intrinsically through the collapse of stalled replication forks, which are induced by a wide range of chemotherapies, or extrinsically through exposure to ionizing radiation. Therefore, ATM inhibition represents an exciting clinical opportunity as a target to hyper-sensitize tumors to chemo/radiotherapy.

Herein, we describe our efforts to identify multiple, novel series of ATM inhibitors. We will describe our optimization efforts with particular attention given to improving the potency of the compounds in cellular systems and the selectivity of the compounds over other closely related proteins (e.g. ATR, mTOR etc.). We will also describe our efforts to optimize both the physicochemical properties of the molecules as well as the pharmacokinetic profile to enable low dose, oral administration in the clinic. These efforts culminated in the discovery of the clinical candidate AZD0156, a first in class orally available ATM inhibitor. AZD0156 shows sub-nanomolar potency in cell based assays of ATM inhibition with selectivities of greater than 1000 fold over other members of the PIKK family of enzymes. AZD0156 is a permeable, highly soluble compound with excellent preclinical pharmacokinetic properties including oral bioavailability. AZD0156 shows robust efficacy in mouse xenograft models after oral administration when combined with DSB inducing agents. AZD0156 is currently undergoing early clinical assessment.

Citation Format: Kurt G. Pike. Identifying high quality, potent and selective inhibitors of ATM kinase: Discovery of AZD0156. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4859.

Discovery of Novel 3-Quinoline Carboxamides as Potent, Selective, and Orally Bioavailable Inhibitors of Ataxia Telangiectasia Mutated (ATM) Kinase

A novel series of 3-quinoline carboxamides has been discovered and optimized as selective inhibitors of the ataxia telangiectasia mutated (ATM) kinase. From a modestly potent HTS hit (4), we identified molecules such as 6-[6-(methoxymethyl)-3-pyridinyl]-4-{[(1R)-1-(tetrahydro-2H-pyran-4-yl)ethyl]amino}-3-quinolinecarboxamide (72) and 7-fluoro-6-[6-(methoxymethyl)pyridin-3-yl]-4-{[(1S)-1-(1-methyl-1H-pyrazol-3-yl)ethyl]amino}quinoline-3-carboxamide (74) as potent and highly selective ATM inhibitors with overall ADME properties suitable for oral administration. 72 and 74 constitute excellent oral tools to probe ATM inhibition in vivo. Efficacy in combination with the DSB-inducing agent irinotecan was observed in a disease relevant model.

Correction: Discovery of 4,6-disubstituted pyrimidines as potent inhibitors of the heat shock factor 1 (HSF1) stress pathway and CDK9. See DOI: 10.1039/c6md00159a

Correction for ‘Discovery of 4,6-disubstituted pyrimidines as potent inhibitors of the heat shock factor 1 (HSF1) stress pathway and CDK9’ by Carl S. Rye et al., Med. Chem. Commun., 2016, 7, 1580–1586.

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

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.

Pyrimidinone nicotinamide mimetics as selective tankyrase and wnt pathway inhibitors suitable for in vivo pharmacology

The canonical Wnt pathway plays an important role in embryonic development, adult tissue homeostasis, and cancer. Germline mutations of several Wnt pathway components, such as Axin, APC, and ß-catenin, can lead to oncogenesis. Inhibition of the poly(ADP-ribose) polymerase (PARP) catalytic domain of the tankyrases (TNKS1 and TNKS2) is known to inhibit the Wnt pathway via increased stabilization of Axin. In order to explore the consequences of tankyrase and Wnt pathway inhibition in preclinical models of cancer and its impact on normal tissue, we sought a small molecule inhibitor of TNKS1/2 with suitable physicochemical properties and pharmacokinetics for hypothesis testing in vivo. Starting from a 2-phenyl quinazolinone hit (compound 1), we discovered the pyrrolopyrimidinone compound 25 (AZ6102), which is a potent TNKS1/2 inhibitor that has 100-fold selectivity against other PARP family enzymes and shows 5 nM Wnt pathway inhibition in DLD-1 cells. Moreover, compound 25 can be formulated well in a clinically relevant intravenous solution at 20 mg/mL, has demonstrated good pharmacokinetics in preclinical species, and shows low Caco2 efflux to avoid possible tumor resistance mechanisms.

Discovery of AZD3147: a potent, selective dual inhibitor of mTORC1 and mTORC2

High throughput screening followed by a lead generation campaign uncovered a novel series of urea containing morpholinopyrimidine compounds which act as potent and selective dual inhibitors of mTORC1 and mTORC2. We describe the continued compound optimization campaign for this series, in particular focused on identifying compounds with improved cellular potency, improved aqueous solubility, and good stability in human hepatocyte incubations. Knowledge from empirical SAR investigations was combined with an understanding of the molecular interactions in the crystal lattice to improve both cellular potency and solubility, and the composite parameters of LLE and pIC50-pSolubility were used to assess compound quality and progress. Predictive models were employed to efficiently mine the attractive chemical space identified resulting in the discovery of 42 (AZD3147), an extremely potent and selective dual inhibitor of mTORC1 and mTORC2 with physicochemical and pharmacokinetic properties suitable for development as a potential clinical candidate.

Predictive blood glucose lowering efficacy by Glucokinase activators in high fat fed female Zucker rats

BACKGROUND AND PURPOSE

Glucokinase (GK) is the rate-limiting enzyme of hepatic glucose metabolism and acts as a sensor for glucose-stimulated insulin release in beta-cells. Here we examine whether the lowering of blood glucose levels in the rat by small molecule glucokinase activators (GKAs) can be predicted from in vitro enzyme potencies and plasma compound exposure.

EXPERIMENTAL APPROACH

We developed an insulin resistant and hyperinsulinemic animal model, the high fat fed female Zucker (fa/fa) rat (HFFZ), and measured the acute in vivo glucose-lowering efficacy of a number of GKAs in an oral glucose tolerance test.

KEY RESULTS

Four GKAs (at 1 to 30 mg kg(-1)), with different in vitro enzyme potencies, dose-dependently improved oral glucose tolerance in HFFZ rats (10-40% decrease glucose area under the curve (AUC) from vehicle control). The extent of glucose lowering, or the pharmacodynamic (PD) effect, of a GKA was directly related to the total compound concentration in the plasma; the pharmacokinetic (PK) measurement. This PK-PD relationship was extended across a series of GKAs by accounting for differences in protein binding and in the in vitro potency.

CONCLUSIONS AND IMPLICATIONS

When the unbound GKA compound level is greater than the in vitro enzyme potency there was significant blood glucose lowering in vivo. This latter relationship was upheld in non-diabetic Wistar rats orally dosed with a GKA. The robust and predictive nature of the PK-PD relationship for GKAs may prove of value in testing these agents in early human clinical studies.

Design of a potent, soluble glucokinase activator with excellent in vivo efficacy

The optimisation of a series of glucokinase activators is described, including attempts to uncouple the relationship between potency and plasma protein binding, and to better understand the key pharmacokinetic properties of the series. The use of unbound clearance as an optimisation parameter facilitated the identification of GKA50, a compound which combines excellent potency and pharmacokinetics with good free drug levels and solubility, and exhibits in vivo efficacy at 1mg/kg po in an acute rat OGTT model.

A novel series of p38 MAP kinase inhibitors for the potential treatment of rheumatoid arthritis

A novel p38 MAP kinase inhibitor structural class was discovered through selectivity screening. The rational analogue design, synthesis and structure-activity relationship of this series of bis-amide inhibitors is reported. The inhibition in vitro of human p38alpha enzyme activity and lipopolysaccharide-induced tumour necrosis factor-alpha release is described for the series. The activity in vivo and pharmacokinetic properties are exemplified for the more potent analogues.