Martina Fitzek

Discovery of (R)-8-(1-(3,5-difluorophenylamino)ethyl)-N,N-dimethyl-2-morpholino-4-oxo-4H-chromene-6-carboxamide (AZD8186): a potent and selective inhibitor of PI3Kβ and PI3Kδ for the treatment of PTEN-deficient cancers.

Several studies have highlighted the dependency of PTEN deficient tumors to PI3Kβ activity and specific inhibition of PI3Kδ has been shown activity against human B-cell cancers. We describe the discovery and optimization of a series of 8-(1-anilino)ethyl)-2-morpholino-4-oxo-4H-chromene-6-carboxamides as PI3Kβ/δ inhibitors, which led to the discovery of the clinical candidate 13, also known as AZD8186. On the basis of the lower lipophilicity of the chromen-4-one core compared to the previously utilized pyrido[1,2-a]pyrimid-4-one core, this series of compounds displayed high metabolic stability and suitable physical properties for oral administration. Compound 13 showed profound pharmacodynamic modulation of p-Akt in PTEN-deficient PC3 prostate tumor bearing mice after oral administration and showed complete inhibition of tumor growth in the mouse PTEN-deficient PC3 prostate tumor xenograft model. 13 was selected as a clinical candidate for treatment of PTEN-deficient cancers and has recently entered phase I clinical trials.

Discovery of novel imidazo[1,2-a]pyridines as inhibitors of the insulin-like growth factor-1 receptor tyrosine kinase

We disclose a novel series of insulin-like growth factor-1 receptor kinase inhibitors based on the 3-(pyrimidin-4-yl)-imidazo[1,2-a]pyridine scaffold. The influence on the inhibitory activity of substitution on the imidazopyridine and at the C5 position of the pyrimidine is discussed. In the course of this optimization, we discovered a potent and selective inhibitor with suitable pharmacokinetics for oral administration.

Inhibition of PI3Kβ Signaling with AZD8186 Inhibits Growth of PTEN-Deficient Breast and Prostate Tumors Alone and in Combination with Docetaxel

Loss of PTEN protein results in upregulation of the PI3K/AKT pathway, which appears dependent on the PI3Kβ isoform. Inhibitors of PI3Kβ have potential to reduce growth of tumors in which loss of PTEN drives tumor progression. We have developed a small-molecule inhibitor of PI3Kβ and PI3Kδ (AZD8186) and assessed its antitumor activity across a panel of cell lines. We have then explored the antitumor effects as single agent and in combination with docetaxel in triple-negative breast (TNBC) and prostate cancer models. In vitro, AZD8186 inhibited growth of a range of cell lines. Sensitivity was associated with inhibition of the AKT pathway. Cells sensitive to AZD8186 (GI50 < 1 μmol/L) are enriched for, but not exclusively associated with, PTEN deficiency. In vivo, AZD8186 inhibits PI3K pathway biomarkers in prostate and TNBC tumors. Scheduling treatment with AZD8186 shows antitumor activity required only intermittent exposure, and that increased tumor control is achieved when AZD8186 is used in combination with docetaxel. AZD8186 is a potent inhibitor of PI3Kβ with activity against PI3Kδ signaling, and has potential to reduce growth of tumors dependent on dysregulated PTEN for growth. Moreover, AZD8186 can be combined with docetaxel, a chemotherapy commonly used to treat advanced TBNC and prostate tumors. The ability to schedule AZD8186 and maintain efficacy offers opportunity to combine AZD8186 more effectively with other drugs. Mol Cancer Ther; 14(1); 48–58. ©2014 AACR.

Discovery of 9-(1-anilinoethyl)-2-morpholino-4-oxo-pyrido[1,2-a]pyrimidine-7-carboxamides as PI3Kβ/δ inhibitors for the treatment of PTEN-deficient tumours

Starting from TGX-221, we designed a series of 9-(1-anilinoethyl)-2-morpholino-4-oxo-pyrido[1,2-a]pyrimidine-7-carboxamides as potent and selective PI3Kβ/δ inhibitors. Structure-activity relationships and structure-property relationships around the aniline and the amide substituents are discussed. We identified compounds 17 and 18, which showed profound pharmacodynamic modulation of phosphorylated Akt in the PC3 prostate tumour xenograft, after a single oral dose. Compound 17 also gave significant inhibition of tumour growth in the PC3 prostate tumour xenograft model after chronic oral dosing.

Discovery of 1-(4-(5-(5-amino-6-(5-tert-butyl-1,3,4-oxadiazol-2-yl)pyrazin-2-yl)-1-ethyl-1,2,4-triazol-3-yl)piperidin-1-yl)-3-hydroxypropan-1-one (AZD8835): A potent and selective inhibitor of PI3Kα and PI3Kδ for the treatment of cancers

Starting from potent inhibitors of PI3Kα having poor general kinase selectivity (e.g., 1 and 2), optimisation of this series led to the identification of 25, a potent inhibitor of PI3Kα (wild type, E545K and H1047R mutations) and PI3Kδ, selective versus PI3Kβ and PI3Kγ, with excellent general kinase selectivity. Compound 25 displayed low metabolic turnover and suitable physical properties for oral administration. In vivo, compound 25 showed pharmacodynamic modulation of AKT phosphorylation and near complete inhibition of tumour growth (93% tumour growth inhibition) in a murine H1047R PI3Kα mutated SKOV-3 xenograft tumour model after chronic oral administration at 25mg/kg b.i.d. Compound 25, also known as AZD8835, is currently in phase I clinical trials.

Design of selective PI3Kα inhibitors starting from a promiscuous pan kinase scaffold.

Starting from compound 1, a potent PI3Kα inhibitor having poor general kinase selectivity, we used structural data and modelling to identify key exploitable differences between PI3Kα and the other kinases. This approach led us to design chemical modifications of the central pyrazole, which solved the poor kinase selectivity seen as a strong liability for the initial compound 1. Amongst the modifications explored, a 1,3,4-triazole ring (as in compound 4) as a replacement of the initial pyrazole provided good potency against PI3Kα, with excellent kinase selectivity.

Discovery of imidazole vinyl pyrimidines as a novel class of kinase inhibitors which inhibit Tie-2 and are orally bioavailable.

Tie-2 is a receptor tyrosine kinase which is involved in angiogenesis and thereby growth of human tumours. The discovery and SAR of a novel class of imidazole-vinyl-pyrimidine kinase inhibitors, which inhibit Tie-2 in vitro is reported. Their synthesis was carried out by condensation of imidazole aldehydes with methyl pyrimidines. These compounds are lead-like, with low molecular weight, good physical properties and oral bioavailability.

Discovery of a series of 8-(2,3-dihydro-1,4-benzoxazin-4-ylmethyl)-2-morpholino-4-oxo-chromene-6-carboxamides as PI3Kβ/δ inhibitors for the treatment of PTEN-deficient tumours

We report the discovery and optimisation of a series of 8-(2,3-dihydro-1,4-benzoxazin-4-ylmethyl)-2-morpholino-4-oxo-chromene-6-carboxamides, leading to compound 16 as a potent and selective PI3Kβ/δ inhibitor: PI3Kβ cell IC50 0.012 μM (in PTEN null MDA-MB-468 cell) and PI3Kδ cell IC50 0.047 μM (in Jeko-1 B-cell), with good pharmacokinetics and physical properties. In vivo, 16 showed profound pharmacodynamic modulation of AKT phosphorylation in a mouse PTEN-deficient PC3 prostate tumour xenograft after a single oral dose and gave excellent tumour growth inhibition in the same model after chronic oral dosing. Compound 16 was selected as a preclinical candidate for the treatment of PTEN-deficient tumours.

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

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC AZD8186 is a novel potent small molecule that targets the lipid kinase PI3Kβ with selectivity vs PI3Kα. AZD8186 reduces pAKT-S473 in the PTEN deficient MDA-MB-468 cell line with an IC50 <5nM, while in the PI3Kα-dependent PIK3CA mutant line BT474 it is 200 fold less potent. AZD8186 also demonstrates cellular activity versus PI3Kβ, inhibiting IgM-dependent pAKT-S473 with an IC50 of 15nM. In cell line panels, sensitivity to AZD8186 is associated in part with loss of PTEN function suggesting that targeting tumours that have lost normal levels of PTEN function through deletion, mutation or down regulation might enrich for sensitivity to AZD8186. Deficiencies in PTEN are described in a number of tumour types such as prostate, squamous lung, breast, renal and glioblastoma. AZD8186 has single anti-tumour activity in pre-clinical models representing each of these settings, which is associated with dynamic regulation of a number of key pathway biomarkers. Clinically, agents such as AZD8186 are likely to be used in combination. The use of AZD8186 in conjunction with either androgen therapy or docetaxol has been explored in cell lines and pre-clinical disease models. Combining AZD8186 with MDV-3100 resulted in synergistic inhibition of LNCAP prostate tumour cell growth, demonstrating the potential to combine with androgen therapy. Moreover in HCC70 (breast) and PC3 (prostate) tumour xenografts AZD8186 shows increased benefit in combination with docetaxel, demonstrating the ability to combine with cytotoxic chemotherapy. Exploration of dose and schedule revealed that efficacy can be maintained in combination with docetaxol at a lower dose of AZD8186 than required for monotherapy activity. Moreover efficacy was maintained when the frequency of AZD8186 dosing was reduced using a shorter intermittent schedule. Understanding how AZD8186 combines with standards of care for PTEN null disease segments provides important insight into how agents targeting PI3Kβ-dependent tumours may be used most effectively in the clinic. [Current affiliation for S. Cosulich is Novartis, Basel, Switzerland.] Citation Format: Urs Hancox, Sabina Cosulich, Hannah Dry, Lynsey Hanson, Clare Crafter, Bernard Barlaam, Martina Fitzek, Lara Ward, Marie Cumberbatch, Steve Powell, Rebecca Ellston, Mandy Lawson, Steve Wedge, Liz Harrington, Stephen Green, Simon T. Barry. AZD8186: a potent selective inhibitor of PI3Kβ targeting PTEN-deficient tumours dependent on dysregulated PI3Kβ signalling. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3264. doi:10.1158/1538-7445.AM2013-3264

Discovery of a series of 8-(1-phenylpyrrolidin-2-yl)-6-carboxamide-2-morpholino-4H-chromen-4-one as PI3Kβ/δ inhibitors for the treatment of PTEN-deficient tumours

Attempts to lock the active conformation of compound 4, a PI3Kβ/δ inhibitor (PI3Kβ cell IC50 0.015μM), led to the discovery of a series of 8-(1-phenylpyrrolidin-2-yl)-6-carboxamide-2-morpholino-4H-chromen-4-ones, which showed high levels of potency and selectivity as PI3Kβ/δ inhibitors. Compound 10 proved exquisitely potent and selective: PI3Kβ cell IC50 0.0011μM in PTEN null MDA-MB-468 cell and PI3Kδ cell IC50 0.014μM in Jeko-1 B-cell, and exhibited suitable physical properties for oral administration. In vivo, compound 10 showed profound pharmacodynamic modulation of AKT phosphorylation in a mouse PTEN-null PC3 prostate tumour xenograft after a single oral dose and gave excellent tumour growth inhibition in the same model after chronic oral dosing. Based on these results, compound 10 was selected as one of our PI3Kβ/δ preclinical candidates.