Compelling molecular biology publications have reported the implication of phosphoinositide kinase PI3Kβ in PTEN-deficient cell line growth and proliferation. These findings supported a scientific rationale for the development of PI3Kβ-specific inhibitors for the treatment of PTEN-deficient cancers. This paper describes the discovery of 2-[2-(2,3-dihydro-indol-1-yl)-2-oxo-ethyl]-6-morpholin-4-yl-3H-pyrimidin-4-one (7) and the optimization of this new series of active and selective pyrimidone indoline amide PI3Kβ inhibitors. 2-[2-(2-Methyl-2,3-dihydro-indol-1-yl)-2-oxo-ethyl]-6-morpholin-4-yl-3H-pyrimidin-4-one (28), identified following a carefully designed methyl scan, displayed improved physicochemical and in vitro pharmacokinetic properties. Structural biology efforts enabled the acquisition of the first X-ray cocrystal structure of p110β with the selective inhibitor compound 28 bound to the ATP site. The nonplanar binding mode described herein is consistent with observed structure-activity relationship for the series. Compound 28 demonstrated significant in vivo activity in a UACC-62 xenograft model in mice, warranting further preclinical investigation. Following successful development, compound 28 entered phase I/Ib clinical trial in patients with advanced cancer.

Most of the phosphoinositide-3 kinase (PI3K) kinase inhibitors currently in clinical trials for cancer treatment exhibit pan PI3K isoform profiles. Single PI3K isoforms differentially control tumorigenesis, and PI3Kβ has emerged as the isoform involved in the tumorigenicity of PTEN-deficient tumors. Herein we describe the discovery and optimization of a new series of benzimidazole- and benzoxazole-pyrimidones as small molecular mass PI3Kβ-selective inhibitors. Starting with compound 5 obtained from a one-pot reaction via a novel intermediate 1, medicinal chemistry optimization led to the discovery of compound 8, which showed a significant activity and selectivity for PI3Kβ and adequate in vitro pharmacokinetic properties. The X-ray costructure of compound 8 in PI3Kδ showed key interactions and structural features supporting the observed PI3Kβ isoform selectivity. Compound 8 achieved sustained target modulation and tumor growth delay at well tolerated doses when administered orally to SCID mice implanted with PTEN-deficient human tumor xenografts.

CD123, the alpha chain of the IL-3 receptor, is an attractive target for acute myeloid leukemia (AML) treatment. However, cytotoxic antibodies or T cell engagers targeting CD123 had insufficient efficacy or safety in clinical trials. We show that expression of CD64, the high-affinity receptor for human IgG, on AML blasts confers resistance to anti-CD123 antibody-dependent cell cytotoxicity (ADCC) in vitro. We engineer a trifunctional natural killer cell engager (NKCE) that targets CD123 on AML blasts and NKp46 and CD16a on NK cells (CD123-NKCE). CD123-NKCE has potent antitumor activity against primary AML blasts regardless of CD64 expression and induces NK cell activation and cytokine secretion only in the presence of AML cells. Its antitumor activity in a mouse CD123+ tumor model exceeds that of the benchmark ADCC-enhanced antibody. In nonhuman primates, it had prolonged pharmacodynamic effects, depleting CD123+ cells for more than 10 days with no signs of toxicity and very low inflammatory cytokine induction over a large dose range. These results support clinical development of CD123-NKCE.

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The synthesis and pharmacological activity of new nonpeptide angiotensin II (AII) receptor antagonists are presented. These [1,2,4]-triazolo[1,5-c]pyrimidine and 1,2,4-triazolo[4,3-c]pyrimidine derivatives represent a new class of bicyclic antagonists that produced a potent, oral antihypertensive activity in the renal artery-ligated rat model. In vitro, they displayed a high affinity for rat adrenal AII receptors and were found to be specific for the AT1 receptor subtype. A SAR study has shown the importance of the 8-[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl for oral activity and the critical role of alkyl substituents at 5- and 7-positions. No significant differences were found between the [1,5-c] and [4,3-c]series. UP 269-6 (5-methyl-7-n-propyl-8-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl ]- [1,2,4]-triazolo[1,5-c]pyrimidin-2(3H)-one, derivative 29) was selected as the lead compound. It was shown to be a highly potent antihypertensive derivative (decrease in mean arterial pressure of 39.6 +/- 7.2 mmHg at 1 mg/kg po in renal artery-ligated rat) with a long duration of action which displayed a high affinity for adrenal AII receptors with a marked selectivity for the AT1 receptor subtype (Ki AT1 = 24 nM; Ki AT2 = 79,200 nM). This compound is currently undergoing extensive pharmacological and clinical development.