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.

Brain exposure of the ATM inhibitor AZD1390 in humans-a positron emission tomography study

BACKGROUND

The protein kinase ataxia telangiectasia mutated (ATM) mediates cellular response to DNA damage induced by radiation. ATM inhibition decreases DNA damage repair in tumor cells and affects tumor growth. AZD1390 is a novel, highly potent, selective ATM inhibitor designed to cross the blood-brain barrier (BBB) and currently evaluated with radiotherapy in a phase I study in patients with brain malignancies. In the present study, PET was used to measure brain exposure of 11C-labeled AZD1390 after intravenous (i.v.) bolus administration in healthy subjects with an intact BBB.

METHODS

AZD1390 was radiolabeled with carbon-11 and a microdose (mean injected mass 1.21 µg) was injected in 8 male subjects (21-65 y). The radioactivity concentration of [11C]AZD1390 in brain was measured using a high-resolution PET system. Radioactivity in arterial blood was measured to obtain a metabolite corrected arterial input function for quantitative image analysis. Participants were monitored by laboratory examinations, vital signs, electrocardiogram, adverse events.

RESULTS

The brain radioactivity concentration of [11C]AZD1390 was 0.64 SUV (standard uptake value) and reached maximum 1.00% of injected dose at Tmax[brain] of 21 min (time of maximum brain radioactivity concentration) after i.v. injection. The whole brain total distribution volume was 5.20 mL*cm-3. No adverse events related to [11C]AZD1390 were reported.

CONCLUSIONS

This study demonstrates that [11C]AZD1390 crosses the intact BBB and supports development of AZD1390 for the treatment of glioblastoma multiforme or other brain malignancies. Moreover, it illustrates the potential of PET microdosing in predicting and guiding dose range and schedule for subsequent clinical studies.

Abstract 6168: Characterization of ATM inhibitor (AZD1390) distribution and pharmacodynamic changes in brain and glioblastoma in preclinical models to inform on mechanism of action

Ataxia telangiectasia mutated (ATM) kinase is a key factor in DNA double strand break response and is constitutively activated in glioblastoma, leading to marked radioresistance [Bartkova, Carruthers] and therefore an attractive radiosensitisation target in this disease. AZD1390, a potent ATM inhibitor optimized to cross the blood brain barrier, is being evaluated with radiotherapy in Phase 1 (NCT03423628). Positron emission tomography (PET) studies demonstrated AZD1390 brain exposure in healthy human subjects. This study characterises ATM inhibitor penetration and distribution in brain and GBM, as well as pharmacodynamic biomarker changes in human orthotopic GBM patient-derived explant (PDX) models. Radiation +/- AZD1390 treatment was evaluated for compound concentration in plasma and relative abundance in brain/ GBM regions by mass spectrometry imaging (MSI). Parallel samples were analysed by immunohistochemistry for biomarkers of DNA damage response and ATM signalling. We show AZD1390 penetrates brain tissue with preferential compound accumulation into tumour. Higher ratios of AZD1390 in GBM versus normal brain correlate with improved efficacy and greater levels of DNA damage. Moreover, AZD1390 in the GBM region was heterogeneously distributed with MSI characterized specific metabolic clusters having varied AZD1390 intensities. As expected, radiation treatment activated ATM signalling (indicated by increase in pRAD50 and γH2AX positive cells) which was effectively inhibited by AZD1390 co-treatment. Our work provides novel insights into ATM inhibitor pharmacokinetics in brain tumours and demonstrates the benefit of using MSI in conjunction with pharmacodynamic markers to provide a more complete picture of AZD1390 mechanism of action for future translational studies on clinical GBM samples.

Citation Format: Lenka Oplustil O'Connor, Gregory Hamm, Maria Udriste, Stephanie Ling, Joanne Wilson, Steve Durant, Gareth Hughes, Sabina Cosulich, Wenlin Shao, Martin Pass, Gemma Jones, Andrew Pierce, Richard Goodwin, Mark O'Connor, Carl Barrett, Elizabeth Harrington. Characterization of ATM inhibitor (AZD1390) distribution and pharmacodynamic changes in brain and glioblastoma in preclinical models to inform on mechanism of action [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6168.

Capivasertib, an AKT Kinase Inhibitor, as Monotherapy or in Combination with Fulvestrant in Patients with AKT1 E17K-Mutant, ER-Positive Metastatic Breast Cancer

PURPOSE

The activating mutation AKT1 E17K occurs in approximately 7% of estrogen receptor-positive (ER+) metastatic breast cancer (MBC). We report, from a multipart, first-in-human, phase I study (NCT01226316), tolerability and activity of capivasertib, an oral AKT inhibitor, as monotherapy or combined with fulvestrant in expansion cohorts of patients with AKT1 E17K-mutant ER+ MBC.

PATIENTS AND METHODS

Patients with an AKT1 E17K mutation, detected by local (next-generation sequencing) or central (plasma-based BEAMing) testing, received capivasertib 480 mg twice daily, 4 days on, 3 days off, weekly or 400 mg twice daily combined with fulvestrant at the labeled dose. Study endpoints included safety, objective response rate (ORR; RECIST v1.1), progression-free survival (PFS), and clinical benefit rate at 24 weeks (CBR24). Biomarker analyses were conducted in the combination cohort.

RESULTS

From October 2013 to August 2018, 63 heavily pretreated patients received capivasertib (20 monotherapy, 43 combination). ORR was 20% with monotherapy, and within the combination cohort was 36% in fulvestrant-pretreated and 20% in fulvestrant-naïve patients, although the latter group may have had more aggressive disease at baseline. AKT1 E17K mutations were detectable in plasma by BEAMing (95%, 41/43), droplet digital PCR (80%, 33/41), and next-generation sequencing (76%, 31/41). A ≥50% decrease in AKT1 E17K at cycle 2 day 1 was associated with improved PFS. Combination therapy appeared more tolerable than monotherapy [most frequent grade ≥3 adverse events: rash (9% vs. 20%), hyperglycemia (5% vs. 30%), diarrhea (5% vs. 10%)].

CONCLUSIONS

Capivasertib demonstrated clinically meaningful activity in heavily pretreated patients with AKT1 E17K-mutant ER+ MBC, including those with prior disease progression on fulvestrant. Tolerability and activity appeared improved by the combination.

Proliferation and AKT Activity Biomarker Analyses after Capivasertib (AZD5363) Treatment of Patients with ER+ Invasive Breast Cancer (STAKT)

PURPOSE

The STAKT study examined short-term exposure (4.5 days) to the oral selective pan-AKT inhibitor capivasertib (AZD5363) to determine if this drug can reach its therapeutic target in sufficient concentration to significantly modulate key biomarkers of the AKT pathway and tumor proliferation.

PATIENTS AND METHODS

STAKT was a two-stage, double-blind, randomized, placebo-controlled, "window-of-opportunity" study in patients with newly diagnosed ER⁺ invasive breast cancer. Stage 1 assessed capivasertib 480 mg b.i.d. (recommended monotherapy dose) and placebo, and stage 2 assessed capivasertib 360 and 240 mg b.i.d. Primary endpoints were changes from baseline in AKT pathway markers pPRAS40, pGSK3β, and proliferation protein Ki67. Pharmacologic and pharmacodynamic properties were analyzed from blood sampling, and tolerability by adverse-event monitoring.

RESULTS

After 4.5 days' exposure, capivasertib 480 mg b.i.d. (n = 17) produced significant decreases from baseline versus placebo (n = 11) in pGSK3β (H-score absolute change: -55.3, P = 0.006) and pPRAS40 (-83.8, P < 0.0001), and a decrease in Ki67 (absolute change in percentage positive nuclei: -9.6%, P = 0.031). Significant changes also occurred in secondary signaling biomarker pS6 (-42.3, P = 0.004), while pAKT (and nuclear FOXO3a) also increased in accordance with capivasertib's mechanism (pAKT: 81.3, P = 0.005). At doses of 360 mg b.i.d. (n = 5) and 240 mg b.i.d. (n = 6), changes in primary and secondary biomarkers were also observed, albeit of smaller magnitude. Biomarker modulation was dose and concentration dependent, and no new safety signals were evident.

CONCLUSIONS

Capivasertib 480 mg b.i.d. rapidly modulates key biomarkers of the AKT pathway and decreases proliferation marker Ki67, suggesting future potential as an effective therapy in AKT-dependent breast cancers.

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).

Abstract 4868: A preclinical PK/PD model based on a mouse glioblastoma survival model for AZD1390, a novel, brain-penetrant ATM kinase inhibitor, to predict the inhibition of DNA damage response induced by radiation and the human efficacious dose

AZD1390 is a novel, highly selective, brain-penetrant, potent inhibitor of the Ataxia Telangiectasia Mutated (ATM) kinase. ATM is activated in response to double-strand breaks (DSBs) and coordinates cellular responses to ionising radiation and other insults. Radiation is the mainstay of treatment for patients with brain tumors, and glioma cells are exquisitely sensitive to ATM inhibition. Therefore, AZD1390 is in clinical development in combination with radiation therapy for the treatment of patients with Glioblastoma Multiforme (GBM) and brain metastases from solid tumours (NCT03423628). [1] The aim of this work was to develop a translational PK/PD-efficacy model for AZD1390 that would enable the project team to assess the extent/duration of inhibition of target engagement required and help to predict the optimal dose and regimen of AZD1390 to treat patients with brain malignancies in combination with radiation.

Time-course data of pharmacokinetics (PK), pharmacodynamics (PD) and tumor growth inhibition from mouse NCI-H2228 brain tumor orthotopic model studies were used to build a PK-PD/Efficacy or survival model. ATM activation is induced by IR treatment, becoming transiently phosphorylated within minutes of IR exposure and dissipates over a 24-hour period. This model quantitatively and dynamically integrates AZD1390 brain PK to the rate and extent of inhibition of phosphorylation of ATM, a proximal PD marker of ATM kinase activation caused by radiation induced DNA damage in the tumor and rate of induction of cell death (determined by bioluminescence signalling as a measure of tumor growth). In parallel, we also modelled cell cycle profiles in GBM cell lines to complement the in-vivo modelling work. The pATM time-course relative to IR radiation (2 Gy) was modelled using AZD1390 concentrations in the brain tumor and the corresponding pATM inhibition, which was then linked to efficacy by estimating tumor cell kill rate via exponential tumor growth model. The free brain concentration of AZD1390 that resulted in half-maximal inhibition (EC50) of pATM after radiation was estimated to be 0.8 nM (range 0.4 to 1.6 nM). Significant tumor regression in orthotopic tumor model was observed at doses &gt;5 mg/kg. An average pATM inhibition over 24h in the mouse GBM survival model was in the range of 44% (5 mg/kg QD) to 88% (20 mg/kg BD). The % overall survival at 5 mg/kg QD and 20 mg/kg BD dose were 56% and 100%, respectively.

Conclusion: The translation of mouse survival data to clinical schedules is unknown, thus efficacious dose was anchored to pATM inhibition required to deliver significant tumor regression.

References:

1. Durant ST et al., The brain-penetrant clinical ATM inhibitor AZD1390 radiosensitizes and improves survival of preclinical brain tumor models. Sci. Adv. 2018;4.

Citation Format: Venkatesh Pilla Reddy, Andy Sykes, Nicola Colclough, Stephen T. Durant, Lenka Oplustil O'Connor, Matthias Hoch, Nuria Buil Bruna, Serena De Vita, Melinda Merchant, Martin Pass. A preclinical PK/PD model based on a mouse glioblastoma survival model for AZD1390, a novel, brain-penetrant ATM kinase inhibitor, to predict the inhibition of DNA damage response induced by radiation and the human efficacious dose [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4868.

BEECH: a dose-finding run-in followed by a randomised phase II study assessing the efficacy of AKT inhibitor capivasertib (AZD5363) combined with paclitaxel in patients with estrogen receptor-positive advanced or metastatic breast cancer, and in a PIK3CA mutant sub-population

BACKGROUND

BEECH investigated the efficacy of capivasertib (AZD5363), an oral inhibitor of AKT isoforms 1-3, in combination with the first-line weekly paclitaxel for advanced or metastatic estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer, and in a phosphoinositide 3-kinase, catalytic, alpha polypeptide mutation sub-population (PIK3CA+).

PATIENTS AND METHODS

BEECH consisted of an open-label, phase Ib safety run-in (part A) in 38 patients with advanced breast cancer, and a randomised, placebo-controlled, double-blind, phase II expansion (part B) in 110 women with ER+/HER2- metastatic breast cancer. In part A, patients received paclitaxel 90 mg/m2 (days 1, 8 and 15 of a 28-day cycle) with capivasertib taken twice daily (b.i.d.) at two intermittent ascending dosing schedules. In part B, patients were randomly assigned, stratified by PIK3CA mutation status, to receive paclitaxel with either capivasertib or placebo. The primary end point for part A was safety to recommend a dose and schedule for part B; primary end points for part B were progression-free survival (PFS) in the overall and PIK3CA+ sub-population.

RESULTS

Capivasertib was well tolerated, with a 400 mg b.i.d. 4 days on/3 days off treatment schedule selected in part A. In part B, median PFS in the overall population was 10.9 months with capivasertib versus 8.4 months with placebo [hazard ratio (HR) 0.80; P = 0.308]. In the PIK3CA+ sub-population, median PFS was 10.9 months with capivasertib versus 10.8 months with placebo (HR 1.11; P = 0.760). Based on the Common Terminology Criteria for Adverse Event v4.0, the most common grade ≥3 adverse events in the capivasertib group were diarrhoea, hyperglycaemia, neutropoenia and maculopapular rash. Dose intensity of paclitaxel was similar in both groups.

CONCLUSIONS

Capivasertib had no apparent impact on the tolerability and dose intensity of paclitaxel. Adding capivasertib to weekly paclitaxel did not prolong PFS in the overall population or PIK3CA+ sub-population of ER+/HER2- advanced/metastatic breast cancer patients.ClinicalTrials.gov: NCT01625286.

Abstract P2-12-01: Dose- and exposure-response relationship and biomarker correlation analysis in breast tumors from patients treated with capivasertib, an AKT inhibitor, in the STAKT randomized, placebo controlled pre-surgical study

Background: Capivasertib (AZD5363), an AKT1,2,3 inhibitor, significantly improved progression-free and overall survival when added to paclitaxel in triple negative breast cancer (BC) patients (Schmid et al. ASCO 2018). We have previously reported in STAKT, robust target inhibition at 480mg BD versus placebo, including significant decreases in the primary biomarkers (PBs) - Ki67, pPRAS40 & pGSK3β - in primary BCs (Robertson et al. SABCS 2017). We now report the dose- and exposure-response relationship of capivasertib and the correlation between primary and secondary (pAKT, pS6, nuclear FOXO3a) tumor biomarkers.

Design: STAKT was a two-stage, double blind, randomized, placebo controlled 'window-of-opportunity' trial in newly diagnosed ER+ BC patients. Stage 1 assessed capivasertib at a dose of 480mg BD p.o. versus placebo. Stage 2 assessed capivasertib at two lower doses 360mg and 240mg BD. Tumor biopsies were taken prior to 1st dose and after 4.5 days of dosing. Evaluable patients (who required pre-defined minimum baseline PD values for PBs) included placebo (n=11), capivasertib at 480mg (n=17), 360mg (n=5) and 240mg (n=6). Blood samples for pharmacokinetic (PK) studies were scheduled at pre-dose; 2, 4, optional 6 & 8 hrs post first dose on Day 1; ˜2-4 h post last dose on Day 5 (before biopsy). The % change from baseline for PBs were evaluated against the following exposure variables (placebo=0): i) Dose, ii) Observed Cmax Day 1 (˜2h post-dose), iii) Observed plasma concentration on Day 5, iv) Model-predicted plasma concentration Day 5 at time of biopsy, and v) Model-predicted AUC on Day 5. Spearman correlation coefficient measured the strength and direction of association between biomarkers.

Results:

· Significant mean reductions in % change from baseline were observed for the PBs pGSK3β (-39%; p&lt;0.006), pPRAS40 (-50%; p&lt;0.0001) and Ki67 (-23%; p=0.052) at 480mg versus placebo. At 360mg and 240mg, mean % changes from baseline in pGSK3β were -27% and -9%, respectively; in pPRAS40 -45% and -28%, respectively; and in Ki67 0% and +22%, respectively.

· Dose-response relationships for individual % change from baseline could be described by an Emax model for all PBs. Overall, the correlation to PK exposure (observed or predicted) was similar to the correlation to dose.

· Correlation coefficient analyses between biomarkers at capivasertib 480mg BD identified- i) Positive correlations for pGSK3β with Ki67 (ρ = 0.52, p-value &lt; 0.05) & with pS6 (ρ = 0.54, p-value&lt;0.05); ii) Negative correlations between FOXO3a and Ki67 (ρ = -0.75, p-value&lt;0.001) pGSK3β (ρ = -0.71, p-value&lt;0.001) & also pS6 (ρ = -0.61, p-value&lt;0.001).Correlation coefficients for lower doses are not robust due to small sample size in these groups.

Conclusions

· Capivasertib caused dose- and concentration- dependent effects on biomarkers after only 4.5 days.

· Significant changes in the PBs were demonstrated at 480 mg BD. Biomarker changes was observed at 360mg and 240mg BD, but statistical analysis was limited by the small sample size at lower doses.

· Correlation between a number of tumor biomarkers (relative changes) were identified for capivasertib 480mg BD.

Citation Format: Gee J, Coleman RE, Cheung KL, Evans A, Holcombe C, Skene A, Rea D, Ahmed S, Jahan A, Horgan K, Rauchhaus P, Littleford R, Finlay P, Cheung A, Cullberg M, de Bruin E, Foxley A, Koulai L, Pass M, Schiavon G, Rugman P, Deb R, Robertson JFR. Dose- and exposure-response relationship and biomarker correlation analysis in breast tumors from patients treated with capivasertib, an AKT inhibitor, in the STAKT randomized, placebo controlled pre-surgical study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-12-01.

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.

Abstract 4909: Adaptive oncology phase 1 study of first-in-class inhibitor of ataxia telangiectasia mutated protein kinase (ATM), in combination with olaparib

Background: AZD0156 is a highly selective first oral ATM inhibitor in the clinic. Coordinating DNA single and double strand break repair, AZD0156 enhances the preclinical activity of olaparib, leading to its development as an antitumor agent in combination. We report here results from an ongoing phase 1 adaptive dose escalation study of AZD0156 in combination with olaparib.

Methods: This phase I study is to assess the safety, tolerability, pharmacokinetics (PK) and preliminary efficacy of escalating doses of AZD0156 in combination with olaparib in patients with advanced malignancies. AZD0156 is mainly metabolized by CYP3A and FMO, which undergo genetic polymorphism. The flexible language incorporated in the protocol also allow rapid dose escalation beyond subtherapeutic doses.

Results: PK data from the first 2 dose cohorts were lower than predicted and the AZD0156 dose was increased 4 X and dosing changed from QD (daily) to BD (twice daily). The mean terminal half-life of AZD0156 was 9-12 hours and PK was dose proportional. No significant drug-drug interactions (DDI) were observed with olaparib. Minor toxicities included nausea, vomiting and anemia in about 40% of patients in all cohorts. Grade 3 and 4 hematologic toxicities were observed in AZD0156 120mg BD with olaparib 200mg BD, and this dose level was considered intolerable. At doses of AZD0156 of 30 and 60mg BD, active target engagement was demonstrated. PK profile was similar across FMO genotype.

Conclusion: Hematologic toxicities, consistent with the mode of action, emerged as dose-limiting toxicities of AZD0156 in combination with olaparib. Pharmacologically active doses of AZD0156 with olaparib were achieved more quickly in patients by using real-time PK, real-time genotyping, safety, DDI assessment, and PK/PD modelling.

Citation Format: Yingxue Chen, Martin Pass, Nuria Bui Bruna, Christine Stephens, Andrew Pierce, Wouter Hanekom, Hani Gabra, Helen Tomkinson, Nidal Al-Huniti. Adaptive oncology phase 1 study of first-in-class inhibitor of ataxia telangiectasia mutated protein kinase (ATM), in combination with olaparib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4909.

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.

A Phase I Open-Label Study to Identify a Dosing Regimen of the Pan-AKT Inhibitor AZD5363 for Evaluation in Solid Tumors and in PIK3CA-Mutated Breast and Gynecologic Cancers

Purpose: 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.Experimental Design: 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 PIK3CA-mutant breast and gynecologic cancers.Results: MTDs were 320, 480, and 640 mg for continuous (n = 47), 4/7 (n = 21), and 2/7 (n = 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 PIK3CA-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 PIK3CA-mutant cohort were met.Conclusions: 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 PIK3CA-mutant cancers treated with AZD5363. Clin Cancer Res; 24(9); 2050-9. ©2017 AACRSee related commentary by Costa and Bosch, p. 2029.

Abstract P4-04-06: AZD5363, an AKT inhibitor, significantly inhibits key biomarkers of the AKT pathway and Ki67, in a randomized, placebo, controlled study (STAKT) in human breast cancers

Background: AKT is an important intracellular control point through which Type 1 growth factors and IGFR signal. Mutations in PIK3CA, AKT and PTEN are prevalent in estrogen receptor positive (ER+) breast cancer (BC) and have been implicated in resistance to endocrine therapies. AZD5363 is an inhibitor of AKT 1, 2 and 3 currently in Phase 2 trials for BC and other solid cancers.

Design: The study examined whether AZD5363 impacts on key biomarkers within the AKT pathway and their subsequent effects on Ki67, a marker of tumor proliferation. STAKT is a multi-center, two-stage, double blind, randomized, placebo controlled, biomarker 'window-of-opportunity' trial in women with newly diagnosed, previously untreated ER+ BC who were deemed would require chemotherapy as part of their primary treatment regimen. Stage 1 assessed AZD5363 at a dose of 480mg bd p.o. versus matching placebo. Up to 30 patients per arm were permitted, to allow 12 subjects per arm with evaluable paired biopsies - obtained at baseline, and after 4.5 days of AZD5363 / placebo. Primary endpoint markers were pPRAS40, pGSK3β and Ki67 assessed by immunohistochemistry. pPRAS40 and pGSK3β were assessed by H-scores and measured separately for cytoplasmic (cyto), nuclear (nuc) and total (cyto+nuc) staining. Ki67 was assessed as % positive staining of 500 tumor nuclei. Laboratory staff were blinded to treatment arm and whether the biopsies were taken before or after AZD5363/placebo. Changes in marker expression (both absolute and %) between biopsies were calculated, and compared between the two groups. An ANOVA test was applied for normally distributed data and Wilcoxon Mann-Whitney used if not normally distributed.

Results: 28/36 patients were evaluable with patient & tumor characteristics as follows: 17 received AZD5363 and 11 placebo; the median ages were 48 & 49 years respectively. 27 patients were Caucasian and 1 African-American. Tumors were all ER+. For HER2 status 8 were positive & 9 negative in the AZD5363 treated group compared to 2 & 9 respectively in the placebo group.

For pPRAS40 and pGSK3β cyto was the predominant staining while for Ki67 staining was nuclear. Changes in each marker with associated p-values are shown in the table.

MarkerType of change vs baselineDegree of change in AZD5363 arm (n=17)p-value versus placebo arm (n=11)pPRAS40 (H-score)TotalAbsolute-83.8&lt;0.0001Total%-50.2&lt;0.0001CytoAbsolute-90.0&lt;0.0001Cyto%-55.8&lt;0.0001NucAbsolute+6.90.42Nuc%+8.90.94pGSK3β (H-score)TotalAbsolute-55.30.006Total%-39.00.006CytoAbsolute-53.60.006Cyto%-39.20.006NucAbsolute-2.80.065Nuc%-36.50.058Ki67 (% cells+)Absolute-9.60.031%-29.40.052

Conclusions• AZD5363 for 4.5 days caused highly significant falls in pGSK3β and pPRAS40, key markers of AKT pathway activation

• AZD53643 also caused a significant decline in Ki67 even after only 4.5 days of drug. This is one of the shortest 'window'-studies to report such an early effect on proliferation.

• Placebo controlled 'window' studies of this short duration can provide important evidence of the therapeutic potential early in a drug's development.

Citation Format: Robertson JFR, Coleman RE, Cheung KL, Evans A, Holcombe C, Skene A, Rea D, Ahmed S, Jahan A, Kelly S, Horgan K, Rauchhaus P, Littleford R, Foxley A, Lindemann JPO, Pass M, Rugman P, Deb R, Finlay P, Gee JMW. AZD5363, an AKT inhibitor, significantly inhibits key biomarkers of the AKT pathway and Ki67, in a randomized, placebo, controlled study (STAKT) in human breast cancers [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-04-06.

Abstract P5-21-32: AZD5363 in combination with fulvestrant in AKT1-mutant ER-positive metastatic breast cancer

Background: E17K is the most common activating AKT1 mutation and was shown to be a therapeutic target in this multipart Phase 1 study of AZD5363 (NCT01226316), an oral and selective pan-AKT kinase inhibitor, in patients (pts) with AKT1-mutant (AKT1m) advanced solid tumors. In heavily pretreated AKT1m (E17K) ER+ metastatic breast cancer (MBC) pts, monotherapy achieved an objective response rate (ORR) of 20% and a median progression-free survival of 5.5 months (95% CI, 2.9−6.9). Suppression of PI3K-AKT signaling results in induction of ER-dependent transcription, potentially limiting the response to single-agent PI3K/AKT inhibitors. We explored the hypothesis that simultaneous inhibition of AKT and ER signaling would enhance antitumor efficacy in AKT1m ER+ MBC.

Methods: In an expansion of this study, we administered oral AZD5363 400 mg twice daily, 4 days on 3 days off, and fulvestrant 500 mg, to AKT1m (detected in tumor tissue by local screening and/or plasma BEAMing) ER+ HER2– MBC pts, enrolled into a fulvestrant-naïve (FN) or fulvestrant-resistant (FR) cohort (max 24 pts/cohort). Key objectives included safety and efficacy by RECIST v1.1. We report results of a planned interim analysis conducted when 12 pts/cohort reached maturity for assessment of 24-week clinical benefit rate (CBR), defined as the percentage of responders plus those with stable disease (SD) ≥24 weeks.Data cut-off occurred in June 2017.

Results: At the time of analysis, 24 AKT1m pts (23 E17K, 1 E40K) had received treatment. FN had more visceral disease (83.3% vs 66.7%) and ER+/PR– status (25% vs 8.3%) than FR. Median number of prior anticancer regimens was 4.5 (range 1–9) and 6 (2–11) in FN and FR, respectively, with more chemotherapy (CT) and less hormone therapy (HT) exposure in FN vs FR [3 (0–5) vs 2 (0–6) and 2 (0–4) vs 4 (2–6) prior CT and HT, respectively]. Prior palbociclib was received by 1 (8.3%) and 4 (33.3%) pts in FN and FR, respectively. Clinical efficacy is detailed below; CBR was 33% and 42% in FN and FR, respectively (Table 1). There was 1 unconfirmed partial response in patients treated with prior palbociclib and 3 SD. At data cut-off, 18 pts had discontinued treatment: progressive disease, n=12; adverse events (AEs), n=2; other reasons, n=4. AEs were observed in all 24 pts, most commonly diarrhea (71%), nausea (63%), vomiting and decreased appetite (29%). Grade ≥3 AEs occurred in 13 (54%) pts, most frequently maculopapular rash (n=3), nausea, hyperglycemia and back pain (all n=2). Dose reduction due to AEs occurred in 3 pts.

Table 1. Clinical efficacy FNFREligible for interim data cut-off, n1212ORR, n (%)2 (17)4 (33)CBR, n (%)4 (33)5 (42)Confirmed response (complete/partial response), n (%)2 (17)4 (33)SD ≥24 weeks, n (%)2 (17)1 (8)

Conclusions: AZD5363 plus fulvestrant is clinically active in AKT1m ER+ MBC pts, including in pts with demonstrated prior resistance to fulvestrant. Comparatively lower efficacy was observed in the FN cohort; factors that may have potentially contributed (eg disease characteristics) will be explored. cfDNA and genomic data will also be presented.

Citation Format: Smyth LM, Oliveira M, Ciruelos E, Tamura K, El-Khoueiry A, Mita A, You B, Renouf DJ, Sablin M-P, Lluch A, Mayer IA, Bando H, Yamashita H, Ambrose H, de Bruin E, Carr TH, Corcoran C, Foxley A, Lindemann JPO, Maudsley R, Pass M, Rutkowski A, Schiavon G, Banerji U, Scaltriti M, Taylor BS, Chandarlapaty S, Baselga J, Hyman DM. AZD5363 in combination with fulvestrant in AKT1-mutant ER-positive metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-21-32.

Abstract P5-21-05: Withdrawn

This abstract was withdrawn by the authors.

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.

AKT Inhibition in Solid Tumors With AKT1 Mutations

Purpose AKT1 E17K mutations are oncogenic and occur in many cancers at a low prevalence. We performed a multihistology basket study of AZD5363, an ATP-competitive pan-AKT kinase inhibitor, to determine the preliminary activity of AKT inhibition in AKT-mutant cancers. Patients and Methods Fifty-eight patients with advanced solid tumors were treated. The primary end point was safety; secondary end points were progression-free survival (PFS) and response according to Response Evaluation Criteria in Solid Tumors (RECIST). Tumor biopsies and plasma cell-free DNA (cfDNA) were collected in the majority of patients to identify predictive biomarkers of response. Results In patients with AKT1 E17K-mutant tumors (n = 52) and a median of five lines of prior therapy, the median PFS was 5.5 months (95% CI, 2.9 to 6.9 months), 6.6 months (95% CI, 1.5 to 8.3 months), and 4.2 months (95% CI, 2.1 to 12.8 months) in patients with estrogen receptor-positive breast, gynecologic, and other solid tumors, respectively. In an exploratory biomarker analysis, imbalance of the AKT1 E17K-mutant allele, most frequently caused by copy-neutral loss-of-heterozygosity targeting the wild-type allele, was associated with longer PFS (hazard ratio [HR], 0.41; P = .04), as was the presence of coincident PI3K pathway hotspot mutations (HR, 0.21; P = .045). Persistent declines in AKT1 E17K in cfDNA were associated with improved PFS (HR, 0.18; P = .004) and response ( P = .025). Responses were not restricted to patients with detectable AKT1 E17K in pretreatment cfDNA. The most common grade ≥ 3 adverse events were hyperglycemia (24%), diarrhea (17%), and rash (15.5%). Conclusion This study provides the first clinical data that AKT1 E17K is a therapeutic target in human cancer. The genomic context of the AKT1 E17K mutation further conditioned response to AZD5363.

Abstract P3-06-03: The short term effects of an AKT inhibitor (AZD5363) on biomarkers of the AKT pathway and anti-tumour activity in a breast cancer paired biopsy study (STAKT trial)

This abstract was withdrawn by the authors.

Abstract 3041: Blood-brain barrier penetrating ATM inhibitor (AZ32) radiosensitises intracranial gliomas in mice

Ataxia-telangiectasia mutated (ATM) kinase is a central DNA damage response (DDR) component signalling the presence of DNA double strand breaks (DSBs) to DNA repair, checkpoint and survival pathways. Clinical doses of fractionated radiotherapy directed at tumours kill cells by inducing single strand breaks and DSBs, the latter being particularly lethal to all cells if not repaired. Poor survival rates of glioblastoma multiforme (GBM) patients is attributed to an inability to excise all invasive tumor tissue (if operable) and an intrinsic tumour chemo/radioresistance, which has been linked to elevated ATM activity in glioma stem cells.

ATM inhibition (ATMi) radiosensitises cancer cell lines in vitro and in vivo. ATMi also acutely radiosensitises patient-derived glioma stem cells more effectively than by inhibiting other DDR or cell cycle checkpoint components (PARP, ATR, Chk1). Checkpoint-defective glioblastoma multiforme (GBM) cell lines seem to be particularly radio-sensitised by ATMi. In addition, several studies suggest that normal brain is radioprotected when ATM activity is deficient, suggesting ATM is required for apoptosis in neurons. ATMi in brain may therefore provide a wide therapeutic margin. Furthermore, ATM's role in signalling DNA damage independent redox stress has been linked to promoting neoangiogenesis in tumour vasculature. Taken together, these studies suggest ATM is an extremely attractive target to inhibit during and potentially following radiotherapy. However, one impediment to preclinical and clinical studies is that current ATMi's have limited CNS bioavailability.

We report AZ32 as the first known selective, orally bioavailable blood-brain barrier (BBB) penetrating ATMi probe. AZ32 inhibits the DDR and radiosensitizes p53/checkpoint-defective GBM cells in vitro. Oral daily dosing providing sufficient mouse free brain pharmacokinetic exposures over AZ32's ATM IC50, during just four daily doses of whole brain irradiation results in significant improvement in median overall survival of syngeneic orthotopic mouse glioma models (log-rank AZ32/radiation vs. radiation p = 0.0194). Tumor eradication was confirmed by tumor imaging. This result was recapitulated with a human orthotopic model. These findings support the development of clinical grade BBB-penetrating ATMi as a potential treatment for GBM and potentially other intracranial tumours dosed in combination with fractionated radiotherapy used in standard clinical practice.

Citation Format: Steve T. Durant, Jeremy Karlin, Kurt Pike, Nicola Colclough, N Mukhopadhyay, S F. Ahmad, J M. Bekta, M Tokarz, Catherine Bardelle, Gareth Hughes, Bhavika Patel, Andrew Thomason, Elaine Cadogan, Ian Barrett, Alan Lau, Martin Pass, Kristoffer Valerie. Blood-brain barrier penetrating ATM inhibitor (AZ32) radiosensitises intracranial gliomas in mice. [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 3041.

Discovery of a Potent, Selective, Orally Bioavailable, and Efficacious Novel 2-(Pyrazol-4-ylamino)-pyrimidine Inhibitor of the Insulin-like Growth Factor-1 Receptor (IGF-1R)

Optimization of cellular lipophilic ligand efficiency (LLE) in a series of 2-anilino-pyrimidine IGF-1R kinase inhibitors led to the identification of novel 2-(pyrazol-4-ylamino)-pyrimidines with improved physicochemical properties. Replacement of the imidazo[1,2-a]pyridine group of the previously reported inhibitor 3 with the related pyrazolo[1,5-a]pyridine improved IGF-1R cellular potency. Substitution of the amino-pyrazole group was key to obtaining excellent kinase selectivity and pharmacokinetic parameters suitable for oral dosing, which led to the discovery of (2R)-1-[4-(4-{[5-chloro-4-(pyrazolo[1,5-a]pyridin-3-yl)-2-pyrimidinyl]amino}-3,5-dimethyl-1H-pyrazol-1-yl)-1-piperidinyl]-2-hydroxy-1-propanone (AZD9362, 28), a novel, efficacious inhibitor of IGF-1R.

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.

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.

Physician behaviors surrounding the implementation of decision and communication AIDS in a breast cancer clinic: a qualitative analysis of staff intern perceptions

The aim of this paper is to examine how physician behavior facilitated or impeded our implementation of decision and communication aids in a breast cancer clinic. Staff interns provided decision and communication aids to patients and wrote up case notes for each patient they served. We used grounded theory to code our staff interns' case notes. We then identified barriers and facilitators to our program's implementation from each category we generated in the coding. Facilitators included physicians reading patient questions and then bringing the staff interns to the consultation. Barriers included physicians forgetting to bring the staff interns to the appointments and discouraging interns from speaking during the consultation. Physicians vary in their cooperation with our program. Our next steps will be to inquire directly with physicians about how to adapt our program design. We will also seek to position the staff interns as mentees to increase physician commitment to our program.

Discovery of checkpoint kinase inhibitor (S)-5-(3-fluorophenyl)-N-(piperidin-3-yl)-3-ureidothiophene-2-carboxamide (AZD7762) by structure-based design and optimization of thiophenecarboxamide ureas

Checkpoint kinases CHK1 and CHK2 are activated in response to DNA damage that results in cell cycle arrest, allowing sufficient time for DNA repair. Agents that lead to abrogation of such checkpoints have potential to increase the efficacy of such compounds as chemo- and radiotherapies. Thiophenecarboxamide ureas (TCUs) were identified as inhibitors of CHK1 by high throughput screening. A structure-based approach is described using crystal structures of JNK1 and CHK1 in complex with 1 and 2 and of the CHK1-3b complex. The ribose binding pocket of CHK1 was targeted to generate inhibitors with excellent cellular potency and selectivity over CDK1and IKKβ, key features lacking from the initial compounds. Optimization of 3b resulted in the identification of a regioisomeric 3-TCU lead 12a. Optimization of 12a led to the discovery of the clinical candidate 4 (AZD7762), which strongly potentiates the efficacy of a variety of DNA-damaging agents in preclinical models.

Structure-activity relationship of a series of non peptidic RGD integrin antagonists targeting α5β1: part 1

Potent antagonists of the integrin α(5)β(1), which are RGD mimetics built from tyrosine are described. This letter describes the optimization of in vitro potency obtained by variation of two parts of the molecule, the basic group and the linker between the basic group and the phenyl central core.

Structure-activity relationship of a series of non peptidic RGD integrin antagonists targeting α5β1: part 2

Potent antagonists of the integrin α(5)β(1), which are RGD mimetics built from tyrosine are described. This paper describes the optimization of in vitro potency obtained by variation of two parts of the molecule, the central aromatic core and the amide moiety.

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.

Abstract B238: Novel imidazo[1,2-a]pyridines as inhibitors of the IGF-1R tyrosine kinase

The Insulin-like Growth Factor-1 Receptor (IGF-1R) is a receptor tyrosine kinase which plays an important role in cancer by promoting proliferation and survival through activation of the Ras/Raf/MAPK and PI3K/Akt signaling pathways. Deregulation of the IGF-1R axis has been reported in a variety of solid cancers and occurs by overexpression of either the receptor or its ligands (IGF-1 and IGF-2) or by down-regulation of IGF binding proteins (in particular IGFBP3). Therapeutic approaches to inhibit IGF-1R signaling include antibodies targeting the receptor and small molecule inhibitors of the tyrosine kinase. The latter strategy offers a potential advantage by simultaneously inhibiting the closely related Insulin Receptor A (IR-A) tyrosine kinase. Indeed, IR-A can drive tumor growth in some cancer cell lines and has been suggested has a potential escape mechanism for IGF-1R inhibition.

Following a cell based high throughput screening, we have identified a series of imidazo[1,2-a]pyridines inhibiting the IGF-1R kinase. Although hit compounds carried a significant activity against CDK2, modifications of the aniline part has led to more potent and selective inhibitors. We selected 1-[4-[4-[(5-chloro-4-imidazo[1,2-a]pyridin-3-yl-pyrimidin-2-yl)amino]-3-methoxy-phenyl]piperazin-1-yl]ethanone (5) as a lead compound having good pharmacokinetics in pre-clinical species. Compound (5) displays a dual inhibition of IGF-1R and the insulin receptor tyrosine kinase as measured in biochemical assays as well as in cellular auto-phosphorylation assays. Structure-activity relationship around (5) is described for IGF-1R inhibition as well as for the hERG ion channel.

Compound (5) has been assessed in an in vivo efficacy model based on the NIH 3T3 fibroblast cell line transfected to express human IGF-1R and IGF1 ligand. In contrast to the non-transfected parent line, this cell line rapidly grows as a sub-cutaneous xenograft in nude mouse, thus providing a suitable model to measure anti-IGF-1R pharmacology by tumor growth inhibition. The high expression of IGF-1R also enables the generation of good quality PD data using receptor phosphorylation as an endpoint.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B238.

Induction of heart valve lesions by small-molecule ALK5 inhibitors

Aberrant signaling by transforming growth factor-β (TGF-β) and its type I (ALK5) receptor has been implicated in a number of human diseases and this pathway is considered a potential target for therapeutic intervention. Transforming growth factor-β signaling via ALK5 plays a critical role during heart development, but the role of ALK5 in the adult heart is poorly understood. In the current study, the preclinical toxicology of ALK5 inhibitors from two different chemistry scaffolds was explored. Ten-week-old female Han Wistar rats received test compounds by the oral route for three to seven days. Both compounds induced histopathologic heart valve lesions characterized by hemorrhage, inflammation, degeneration, and proliferation of valvular interstitial cells. The pathology was observed in all animals, at all doses tested, and occurred in all four heart valves. Immunohistochemical analysis of ALK5 in rat hearts revealed expression in the valves, but not in the myocardium. Compared to control animals, protein levels of ALK5 were unchanged in the heart valves of treated animals. We also observed a physeal dysplasia in the femoro-tibial joint of rats treated with ALK5 inhibitors, a finding consistent with a pharmacological effect described previously with ALK5 inhibitors. Overall, these findings suggest that TGF-β signaling via ALK5 plays a critical role in maintaining heart valve integrity.

Novel imidazo[1,2-a]pyridine based inhibitors of the IGF-1 receptor tyrosine kinase: optimization of the aniline

Following the discovery of imidazopyridine 1 as a potent IGF-1R tyrosine kinase inhibitor, the aniline part has been modified with the aim to optimize the properties of this series. The structure-activity relationships against IGF-1R kinase activity as well as inhibition of the hERG ion channel are discussed.

Abstract 4477: Characterization of AZD5363, an orally bioavailable, potent ATP-competitive inhibitor of AKT kinases with pharmacodynamic and antitumor activity in preclinical models

AKT is a key node in the most frequently de-regulated signaling pathway in human cancer, and has been shown to mediate resistance to a range of cytotoxic, anti-hormonal and targeted therapies. AZD5363 inhibits all AKT isoforms with a potency of &lt;10 nM, and inhibits phosphorylation of the AKT substrate PRAS40 in BT474c cells with a potency of 0.31 μM. AZD5363 monotherapy inhibits the proliferation of 22/150 solid and hematological tumour cell lines with a potency of &lt; 1μM. Cell lines derived from breast cancers show the highest frequency of response. Pharmacodynamics have been studied in BT474c xenografts growing in nude mice following oral dosing. A dose of 300 mg/kg AZD5363 significantly inhibits pPRAS40, pGSK3β and pS6 for at least 24 h; pPRAS40 was inhibited by 70-90% for 24 h following a 300 mg/kg dose. These biomarkers were also significantly inhibited for at least 8 h following a 100 mg/kg dose. A good correlation was observed between plasma exposure of AZD5363 and inhibition of PRAS40 phosphorylation (EC50 ∼ 0.1 μM). Chronic dosing of AZD5363 causes dose-dependent inhibition of BT474c xenografts; schedules of 300 mg/kg qd and 150 mg/kg bd resulted in &gt;90% inhibition of BT474c xenograft growth. Chronic monotherapy dosing resulted in profound growth inhibition or regression of multiple other xenografts derived from a range of solid tumour types. AZD5363 also greatly enhanced the anti-tumor activity of cytotoxic and novel targeted therapies in xenograft models. It is concluded that AZD5363 is a potent inhibitor of AKT with pharmacodynamic and anti-tumor activity in vivo, and has potential to treat a range of solid and hematological malignancies. AZD5363 is currently in phase 1 clinical trials.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4477. doi:10.1158/1538-7445.AM2011-4477

AZD8055 is a potent, selective, and orally bioavailable ATP-competitive mammalian target of rapamycin kinase inhibitor with in vitro and in vivo antitumor activity

The mammalian target of rapamycin (mTOR) kinase forms two multiprotein complexes, mTORC1 and mTORC2, which regulate cell growth, cell survival, and autophagy. Allosteric inhibitors of mTORC1, such as rapamycin, have been extensively used to study tumor cell growth, proliferation, and autophagy but have shown only limited clinical utility. Here, we describe AZD8055, a novel ATP-competitive inhibitor of mTOR kinase activity, with an IC50 of 0.8 nmol/L. AZD8055 showed excellent selectivity (approximately 1,000-fold) against all class I phosphatidylinositol 3-kinase (PI3K) isoforms and other members of the PI3K-like kinase family. Furthermore, there was no significant activity against a panel of 260 kinases at concentrations up to 10 micromol/L. AZD8055 inhibits the phosphorylation of mTORC1 substrates p70S6K and 4E-BP1 as well as phosphorylation of the mTORC2 substrate AKT and downstream proteins. The rapamycin-resistant T37/46 phosphorylation sites on 4E-BP1 were fully inhibited by AZD8055, resulting in significant inhibition of cap-dependent translation. In vitro, AZD8055 potently inhibits proliferation and induces autophagy in H838 and A549 cells. In vivo, AZD8055 induces a dose-dependent pharmacodynamic effect on phosphorylated S6 and phosphorylated AKT at plasma concentrations leading to tumor growth inhibition. Notably, AZD8055 results in significant growth inhibition and/or regression in xenografts, representing a broad range of human tumor types. AZD8055 is currently in phase I clinical trials.

The discovery and optimisation of pyrido[2,3-d]pyrimidine-2,4-diamines as potent and selective inhibitors of mTOR kinase

We describe a novel series of potent inhibitors of the kinase activity of mTOR. The compounds display good selectivity relative to other PI3K-related kinase family members and, in cellular assays, inhibit both mTORC1 and mTORC2 complexes and exhibit good antiproliferative activity.

Discovery of a novel class of 2-ureido thiophene carboxamide checkpoint kinase inhibitors

Checkpoint kinase-1 (Chk1, CHEK1) is a Ser/Thr protein kinase that mediates the cellular response to DNA-damage. A novel class of 2-ureido thiophene carboxamide urea (TCU) Chk1 inhibitors is described. Inhibitors in this chemotype were optimized for cellular potency and selectivity over Cdk1.

Inhibitors of epidermal growth factor receptor tyrosine kinase: Novel C-5 substituted anilinoquinazolines designed to target the ribose pocket

A series of novel C-5 substituted anilinoquinazolines, selected on the basis of docking experiments and overlays with ATP in the active site of EGFR tyrosine kinase, have been prepared and found to be potent inhibitors. In vivo pharmacokinetics and disease model activity are discussed.