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.

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.

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.

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.

SY13-3 Src is one of the oldest and most studied proto-oncogenes. A constitutively active form of this non-receptor tyrosine kinase, v-Src kinase, encoded by the mutant Src gene within the Rous Sarcoma Virus genome can transform fibroblasts. Although evidence for activating mutations within the cellular Src homologue, c-Src, in human tumours is limited and controversial, there is a significant body of data describing high levels of c-Src kinase expression and activity in many human tumour types. In many cases, this appears to be driven by post-translational activation mechanisms. This has been linked to poor clinical prognosis, tumour progression and in particular, tumour dissemination. These observations are supported by accumulating pre-clinical data suggesting that increased Src kinase activity predominantly leads to changes in cell behaviour that contribute to an invasive tumour phenotype. The increased understanding of the role of Src kinase in multiple signalling pathways together with structural knowledge of the kinase and their implications for rational drug design has led to renewed interest in Src as a therapeutic target in cancer. Here we report on the structure activity relationships and key pre-clinical findings that led to the discovery of AZD0530 as an orally available, highly potent, dual specific inhibitor of Src and Abl kinases. Clinical studies in healthy volunteers have demonstrated the tolerability of AZD0530 during once daily continuous oral dosing and have provided, for the first time, pharmacodynamic data to indicate an AZD0530 dose dependent inhibition of Src dependant activity in man. Clinical plans to explore the Src and Abl kinase activity of this well tolerated and clinically active compound are currently being developed.