Nutritional Status Improved in Cystic Fibrosis Patients with the G551D Mutation After Treatment with Ivacaftor.

BACKGROUND: The cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gating mutation G551D prevents sufficient ion transport due to reduced channel-open probability. Ivacaftor, an oral CFTR potentiator, increases the channel-open probability. AIM: To further analyze improvements in weight and body mass index (BMI) in two studies of ivacaftor in patients aged ≥6 years with CF and the G551D mutation. METHODS: Patients were randomized 1:1 to ivacaftor 150 mg or placebo every 12 h for 48 weeks. Primary end point (lung function) was reported previously. Other outcomes included weight and height measurements and CF Questionnaire-Revised (CFQ-R). RESULTS: Studies included 213 patients (aged ≤ 20 years, n = 105; aged > 20 years, n = 108). In patients ≤20 years, adjusted mean change from baseline to week 48 in body weight was 4.9 versus 2.2 kg (ivacaftor vs. placebo, p = 0.0008). At week 48, change from baseline in mean weight-for-age z-score was 0.29 versus -0.06 (p < 0.0001); change in mean BMI-for-age z-score was 0.26 versus -0.13 (p < 0.0001). In patients >20 years, adjusted mean change from baseline to week 48 in body weight was 2.7 versus -0.2 kg (p = 0.0003). Mean BMI change at week 48 was 0.9 versus -0.1 kg/m(2) (p = 0.0003). There was no linear correlation evident between changes in body weight and improvements in lung function or sweat chloride. Significant CFQ-R improvements were seen in perception of eating, body image, and sense of ability to gain weight. CONCLUSIONS: Nutritional status improved following treatment with ivacaftor for 48 weeks.

Evaluation of cynomolgus monkeys for the identification of endogenous biomarkers for hepatic transporter inhibition and as a translatable model to predict pharmacokinetic interactions with statins in humans.

Inhibition of hepatic transporters such as organic anion transporting polypeptides (OATPs) 1B can cause drug-drug interactions (DDIs). Determining the impact of perpetrator drugs on the plasma exposure of endogenous substrates for OATP1B could be valuable to assess the risk for DDIs early in drug development. As OATP1B orthologs are well conserved between human and monkey, we assessed in cynomolgus monkeys the endogenous OATP1B substrates that are potentially suitable to assess DDI risk in humans. The effect of rifampin (RIF), a potent inhibitor for OATP1B, on plasma exposure of endogenous substrates of hepatic transporters was measured. From the 18 biomarkers tested, RIF (18 mg/kg, oral) caused significant elevation of plasma unconjugated and conjugated bilirubin, which may be attributed to inhibition of cOATP1B1 and cOATP1B3 based on in vitro to in vivo extrapolation analysis. To further evaluate whether cynomolgus monkeys are a suitable translational model to study OATP1B-mediated DDIs, we determined the inhibitory effect of RIF on in vitro transport and pharmacokinetics of rosuvastatin (RSV) and atorvastatin (ATV). RIF strongly inhibited the uptake of RSV and ATV by cOATP1B1 and cOATP1B3 in vitro. In agreement with clinical observations, RIF (18 mg/kg, oral) significantly decreased plasma clearance and increased the area under the plasma concentration curve (AUC) of intravenously administered RSV by 2.8- and 2.7-fold, and increased the AUC and maximum plasma concentration of orally administered RSV by 6- and 10.3-fold, respectively. In contrast to clinical findings, RIF did not significantly increase plasma exposure of either intravenous or orally administered ATV, indicating species differences in the rate-limiting elimination pathways.

Nonpungent capsaicin analogs (capsinoids) increase energy expenditure through the activation of brown adipose tissue in humans.

BACKGROUND: Capsinoids-nonpungent capsaicin analogs-are known to activate brown adipose tissue (BAT) thermogenesis and whole-body energy expenditure (EE) in small rodents. BAT activity can be assessed by [¹8F]fluorodeoxyglucose-positron emission tomography (FDG-PET) in humans. OBJECTIVES: The aims of the current study were to examine the acute effects of capsinoid ingestion on EE and to analyze its relation to BAT activity in humans. DESIGN: Eighteen healthy men aged 20-32 y underwent FDG-PET after 2 h of cold exposure (19°C) while wearing light clothing. Whole-body EE and skin temperature, after oral ingestion of capsinoids (9 mg), were measured for 2 h under warm conditions (27°C) in a single-blind, randomized, placebo-controlled, crossover design. RESULTS: When exposed to cold, 10 subjects showed marked FDG uptake into adipose tissue of the supraclavicular and paraspinal regions (BAT-positive group), whereas the remaining 8 subjects (BAT-negative group) showed no detectable uptake. Under warm conditions (27°C), the mean (±SEM) resting EE was 6114 ± 226 kJ/d in the BAT-positive group and 6307 ± 156 kJ/d in the BAT-negative group (NS). EE increased by 15.2 ± 2.6 kJ/h in 1 h in the BAT-positive group and by 1.7 ± 3.8 kJ/h in the BAT-negative group after oral ingestion of capsinoids (P < 0.01). Placebo ingestion produced no significant change in either group. Neither capsinoids nor placebo changed the skin temperature in various regions, including regions close to BAT deposits. CONCLUSION: Capsinoid ingestion increases EE through the activation of BAT in humans. This trial was registered at http://www.umin.ac.jp/ctr/ as UMIN 000006073.