Notch signaling is an area of great interest in oncology. RO4929097 is a potent and selective inhibitor of γ-secretase, producing inhibitory activity of Notch signaling in tumor cells. The RO4929097 IC50 in cell-free and cellular assays is in the low nanomolar range with >100-fold selectivity with respect to 75 other proteins of various types (receptors, ion channels, and enzymes). RO4929097 inhibits Notch processing in tumor cells as measured by the reduction of intracellular Notch expression by Western blot. This leads to reduced expression of the Notch transcriptional target gene Hes1. RO4929097 does not block tumor cell proliferation or induce apoptosis but instead produces a less transformed, flattened, slower-growing phenotype. RO4929097 is active following oral dosing. Antitumor activity was shown in 7 of 8 xenografts tested on an intermittent or daily schedule in the absence of body weight loss or Notch-related toxicities. Importantly, efficacy is maintained after dosing is terminated. Angiogenesis reverse transcription-PCR array data show reduced expression of several key angiogenic genes. In addition, comparative microarray analysis suggests tumor cell differentiation as an additional mode of action. These preclinical results support evaluation of RO4929097 in clinical studies using an intermittent dosing schedule. A multicenter phase I dose escalation study in oncology is under way.
AIMSRT2104 is a novel, first-in-class, highly selective small molecule activator of the NAD + dependent deacetylase SIRT1. SRT2104 was dosed to healthy male and female volunteers in a series of phase 1 clinical studies that were designed to elucidate tolerability and pharmacokinetics associated with oral dosing to aid in dose selection for subsequent clinical trials. METHODSIn the first-in-human study, there was both a single dose phase and 7 day repeat dose phase. Doses used ranged from 0.03 to 3.0 g. A radioactive microtracer study was subsequently conducted to determine systemic clearance, bioavailability and preliminary metabolism, and a crossover study was conducted to determine the effect of gender, formulation and feeding state on SRT2104 pharmacokinetics. RESULTSSRT2104 was well tolerated in all of these studies, with no serious adverse reactions observed. SRT2104 displayed a dose-dependent, but sub-proportional increase in exposure following single dose and repeated dose administration. Accumulation of three-fold or less occurs after 7 days of repeat dosing. The mean bioavailability was circa 14% and the mean clearance was circa 400 ml min -1. Although there were no substantial effects on exposure resulting from gender or formulation differences, a notable food effect was observed, manifested as up to four-fold increase in exposure parameters. CONCLUSIONSIn the absence of an optimized formulation of SRT2104, the food effect can be used to maximize exposure in future clinical studies. Combined with the good tolerability of all doses demonstrated in these studies, the favourable selectivity profile of SRT2104 allows for the use of this SIRT1 modulator for target validation in the clinic.
In vitro prediction of physiologically relevant transport of therapeutic molecules across the microcirculation represents an intriguing opportunity to predict efficacy in human populations. On‐chip microvascular networks (MVNs) show physiologically relevant values of molecular permeability, yet like most systems, they lack an important contribution to transport: the ever‐present fluid convection through the endothelium. Quantification of transport through the MVNs by current methods also requires confocal imaging and advanced analytical techniques, which can be a bottleneck in industry and academic laboratories. Here, it is shown that by recapitulating physiological transmural flow across the MVNs, the concentration of small and large molecule therapeutics can be directly sampled in the interstitial fluid and analyzed using standard analytical techniques. The magnitudes of transport measured in MVNs reveal trends with molecular size and type (protein versus nonprotein) that are expected in vivo, supporting the use of the MVNs platform as an in vitro tool to predict distribution of therapeutics in vivo.
The effects of intravenous practolol 0.4 mg/kg were studied in 12 hypertensive patients during halothane/nitrous oxide anaesthesia. Practolol decreased heart rate (HR) and cardiac output (Q) from the elevated levels following atropine administration during anaesthesia, but values of arterial pressure (AP), HR and Q after the combination of atropine and practolol were not significantly different from those during anaesthesia prior to blockade. The effects of a similar anaesthetic sequence were studied in a further 11 treated hypertensive patients given practolol by mouth 1.5 mg/kg/6 hours for at least 48 hours preoperatively in addition to current anti-hypertensive therapy. By comparison with treated hypertensive patients previously studied, those pretreated with practolol had similar AP awake, but higher AP throughout anaesthesia with either spontaneous or artificial ventilation. Cardiac output was higher and systemic vascular resistance was lower both before and during anaesthesia. Both the present groups of patients showed significantly attenuated responses of tachycardia and hypertension following laryngoscopy and intubation compared with previous studies. The incidence of dysrhythmia and e.c.g. evidence of myocardial ischaemia was significantly lower (4%) in beta-blocked patients compared with those who had not received practolol (38%).
Potent and selective antagonists of the voltage-gated sodium channel Na1.7 represent a promising avenue for the development of new chronic pain therapies. We generated a small molecule atropisomer quinolone sulfonamide antagonist AMG8379 and a less active enantiomer AMG8380. Here we show that AMG8379 potently blocks human Na1.7 channels with an IC of 8.5 nM and endogenous tetrodotoxin (TTX)-sensitive sodium channels in dorsal root ganglion (DRG) neurons with an IC of 3.1 nM in whole-cell patch clamp electrophysiology assays using a voltage protocol that interrogates channels in a partially inactivated state. AMG8379 was 100- to 1000-fold selective over other Na family members, including Na1.4 expressed in muscle and Na1.5 expressed in the heart, as well as TTX-resistant Na channels in DRG neurons. Using an ex vivo mouse skin-nerve preparation, AMG8379 blocked mechanically induced action potential firing in C-fibers in both a time-dependent and dose-dependent manner. AMG8379 similarly reduced the frequency of thermally induced C-fiber spiking, whereas AMG8380 affected neither mechanical nor thermal responses. In vivo target engagement of AMG8379 in mice was evaluated in multiple Na1.7-dependent behavioral endpoints. AMG8379 dose-dependently inhibited intradermal histamine-induced scratching and intraplantar capsaicin-induced licking, and reversed UVB radiation skin burn-induced thermal hyperalgesia; notably, behavioral effects were not observed with AMG8380 at similar plasma exposure levels. AMG8379 is a potent and selective Na1.7 inhibitor that blocks sodium current in heterologous cells as well as DRG neurons, inhibits action potential firing in peripheral nerve fibers, and exhibits pharmacodynamic effects in translatable models of both itch and pain.
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