Characterization of LY3023414, a Novel PI3K/mTOR Dual Inhibitor Eliciting Transient Target Modulation to Impede Tumor Growth.

The PI3K/AKT/mTOR pathway is among the most frequently altered pathways in cancer cell growth and survival. LY3023414 is a complex fused imidazoquinolinone with high solubility across a wide pH range designed to inhibit class I PI3K isoforms and mTOR kinase. Here, we describe the in vitro and in vivo activity of LY3023414. LY3023414 was highly soluble at pH 2-7. In biochemical testing against approximately 266 kinases, LY3023414 potently and selectively inhibited class I PI3K isoforms, mTORC1/2, and DNA-PK at low nanomolar concentrations. In vitro, inhibition of PI3K/AKT/mTOR signaling by LY3023414 caused G1 cell-cycle arrest and resulted in broad antiproliferative activity in cancer cell panel screens. In vivo, LY3023414 demonstrated high bioavailability and dose-dependent dephosphorylation of PI3K/AKT/mTOR pathway downstream substrates such as AKT, S6K, S6RP, and 4E-BP1 for 4 to 6 hours, reflecting the drug's half-life of 2 hours. Of note, equivalent total daily doses of LY3023414 given either once daily or twice daily inhibited tumor growth to similar extents in multiple xenograft models, indicating that intermittent target inhibition is sufficient for antitumor activity. In combination with standard-of-care drugs, LY3023414 demonstrated additive antitumor activity. The novel, orally bioavailable PI3K/mTOR inhibitor LY3023414 is highly soluble and exhibits potent in vivo efficacy via intermittent target inhibition. It is currently being evaluated in phase I and II trials for the treatment of human malignancies. Mol Cancer Ther; 15(10); 2344-56. ©2016 AACR.

Pharmacological inhibition of nicotinamide phosphoribosyltransferase (NAMPT), an enzyme essential for NAD+ biosynthesis, in human cancer cells: metabolic basis and potential clinical implications.

Nicotinamide phosphoribosyltransferase (NAMPT) catalyzes the first rate-limiting step in converting nicotinamide to NAD(+), essential for cellular metabolism, energy production, and DNA repair. NAMPT has been extensively studied because of its critical role in these cellular processes and the prospect of developing therapeutics against the target, yet how it regulates cellular metabolism is not fully understood. In this study we utilized liquid chromatography-mass spectrometry to examine the effects of FK866, a small molecule inhibitor of NAMPT currently in clinical trials, on glycolysis, the pentose phosphate pathway, the tricarboxylic acid (TCA) cycle, and serine biosynthesis in cancer cells and tumor xenografts. We show for the first time that NAMPT inhibition leads to the attenuation of glycolysis at the glyceraldehyde 3-phosphate dehydrogenase step due to the reduced availability of NAD(+) for the enzyme. The attenuation of glycolysis results in the accumulation of glycolytic intermediates before and at the glyceraldehyde 3-phosphate dehydrogenase step, promoting carbon overflow into the pentose phosphate pathway as evidenced by the increased intermediate levels. The attenuation of glycolysis also causes decreased glycolytic intermediates after the glyceraldehyde 3-phosphate dehydrogenase step, thereby reducing carbon flow into serine biosynthesis and the TCA cycle. Labeling studies establish that the carbon overflow into the pentose phosphate pathway is mainly through its non-oxidative branch. Together, these studies establish the blockade of glycolysis at the glyceraldehyde 3-phosphate dehydrogenase step as the central metabolic basis of NAMPT inhibition responsible for ATP depletion, metabolic perturbation, and subsequent tumor growth inhibition. These studies also suggest that altered metabolite levels in tumors can be used as robust pharmacodynamic markers for evaluating NAMPT inhibitors in the clinic.

Posttraumatic growth after childbirth: a prospective study.

A growing body of research has examined the potential for positive change following challenging and traumatic events, this is known as posttraumatic growth (PTG). Childbirth is a valuable opportunity to extend previous work on PTG as it allows the role of different variables to be considered prospectively. The aim of this study was to prospectively examine correlates of PTG after birth, including sociodemographic and obstetric variables, social support and psychological distress, using a prospective, longitudinal design. A total of 125 women completed questionnaires during their third trimester of pregnancy and 8 weeks after birth. At least a small degree of positive change following childbirth was reported by 47.9% of women; however, average levels of growth were lower than generally reported in other studies. A regression model of age, type of delivery, posttraumatic stress symptoms during pregnancy and general distress after birth significantly predicted 32% of the variance in growth after childbirth. The strongest predictors of growth were operative delivery (ß 0.23-0.30) and posttraumatic stress symptoms in pregnancy (ß 0.32). These findings emphasise the importance of assessing pre-event characteristics when considering the development of PTG after a challenging event.

Tasisulam sodium, an antitumor agent that inhibits mitotic progression and induces vascular normalization.

LY573636-sodium (tasisulam) is a small molecule antitumor agent with a novel mechanism of action currently being investigated in a variety of human cancers. In vitro, tasisulam induced apoptosis via the intrinsic pathway, resulting in cytochrome c release and caspase-dependent cell death. Using high content cellular imaging and subpopulation analysis of a wide range of in vitro and in vivo cancer models, tasisulam increased the proportion of cells with 4N DNA content and phospho-histone H3 expression, leading to G(2)-M accumulation and subsequent apoptosis. Tasisulam also blocked VEGF, epidermal growth factor, and fibroblast growth factor-induced endothelial cell cord formation but did not block acute growth factor receptor signaling (unlike sunitinib, which blocks VEGF-driven angiogenesis at the receptor kinase level) or induce apoptosis in primary endothelial cells. Importantly, in vivo phenocopying of in vitro effects were observed in multiple human tumor xenografts. Tasisulam was as effective as sunitinib at inhibiting neovascularization in a Matrigel plug angiogenesis assay in vivo and also caused reversible, non G(2)-M-dependent growth arrest in primary endothelial cells. Tasisulam also induced vascular normalization in vivo. Interestingly, the combination of tasisulam and sunitinib significantly delayed growth of the Caki-1 renal cell carcinoma model, whereas neither agent was active alone. These data show that tasisulam has a unique, dual-faceted mechanism of action involving mitotic catastrophe and antiangiogenesis, a phenotype distinct from conventional chemotherapies and published anticancer agents.

Binary insecticidal crystal protein from Bacillus thuringiensis, strain PS149B1: effects of individual protein components and mixtures in laboratory bioassays.

A family of novel binary insecticidal crystal proteins, with activity against western corn rootworm, Diabrotica virgifera virgifera LeConte, was identified from Bacillus thuringiensis Berliner. A binary insecticidal crystal protein (bICP) from B. thuringiensis strain PS149B1 is composed of a 14-kDa protein (Cry34Abl) and a 44-kDaprotein (Cry35Ab1). These proteins have been co-expressed in transgenic maize plants, Zea mays L., and effectively control western corn rootworm larvae under field conditions. Laboratory experiments were conducted to better understand the contribution of each component protein to the in vivo activity of the bICP. The 14-kDa protein is active alone against southern corn rootworm, Diabrotica undecimpunctata howardi Barber, and was synergized by the 44-kDa protein. In mixtures, the concentration of the 14-kDa protein had a greater impact on efficacy than the 44-kDa component. Although both proteins are clearly required for maximal insecticidal activity, laboratory results did not support the formation of a stable, fixed-ratio complex of the two component proteins.