Impact of the molar activity and PSMA expression level on [18F]AlF-PSMA-11 uptake in prostate cancer.

This two-part preclinical study aims to evaluate prostate specific membrane antigen (PSMA) as a valuable target for expression-based imaging applications and to determine changes in target binding in function of varying apparent molar activities (MAapp) of [18F]AlF-PSMA-11. For the evaluation of PSMA expression levels, male NOD/SCID mice bearing prostate cancer (PCa) xenografts of C4-2 (PSMA+++), 22Rv1 (PSMA+) and PC-3 (PSMA-) were administered [18F]AlF-PSMA-11 with a medium MAapp (20.24 ± 3.22 MBq/nmol). SUVmean and SUVmax values were respectively 3.22 and 3.17 times higher for the high versus low PSMA expressing tumors (p < 0.0001). To evaluate the effect of varying MAapp, C4-2 and 22Rv1 xenograft bearing mice underwent additional [18F]AlF-PSMA-11 imaging with a high (211.2 ± 38.9 MBq/nmol) and/or low MAapp (1.92 ± 0.27 MBq/nmol). SUV values showed a significantly increasing trend with higher MAapp. Significant changes were found for SUVmean and SUVmax between the high versus low MAapp and medium versus low MAapp (both p < 0.05), but not between the high versus medium MAapp (p = 0.055 and 0.25, respectively). The effect of varying MAapp was more pronounced in low expressing tumors and PSMA expressing tissues (e.g. salivary glands and kidneys). Overall, administration of a high MAapp increases the detection of low expression tumors while also increasing uptake in PSMA expressing tissues, possibly leading to false positive findings. In radioligand therapy, a medium MAapp could reduce radiation exposure to dose-limiting organs with only limited effect on radionuclide accumulation in the tumor.

Quantitative and Qualitative Analyses of Biodistribution and PET Image Quality of a Novel Radiohybrid PSMA, 18F-rhPSMA-7, in Patients with Prostate Cancer.

Radiohybrid PSMA (rhPSMA) ligands, a new class of theranostic prostate-specific membrane antigen (PSMA)-targeting agents, feature fast 18F synthesis and utility for labeling with radiometals. Here, we assessed the biodistribution and image quality of 18F-rhPSMA-7 to determine the best imaging time point for patients with prostate cancer. Methods: In total, 202 prostate cancer patients who underwent a clinically indicated 18F-rhPSMA-7 PET/CT were retrospectively analyzed, and 12 groups based on the administered activity and uptake time of PET scanning were created: 3 administered activities (low, 222-296 MBq; moderate, 297-370 MBq; and high, 371-444 MBq) and 4 uptake time points (short, 50-70 min; intermediate, 71-90 min; long, 91-110 min; and extra long, ≥111 min). For quantitative analyses, SUVmean and organ- or tumor-to-background ratio were determined for background, healthy organs, and 3 representative tumor lesions. Qualitative analyses assessed overall image quality, nonspecific blood-pool activity, and background uptake in bone or marrow using 3- or 4-point scales. Results: In quantitative analyses, SUVmean showed a significant decrease in the blood pool and lungs and an increase in the kidneys, bladder, and bones as the uptake time increased. SUVmean showed a trend to increase in the blood pool and bones as the administered activity increased. However, no significant differences were found in 377 tumor lesions with respect to the administered activity or uptake time. In qualitative analyses, the overall image quality was stable along with the uptake time, but the proportion rated to have good image quality decreased as the administered activity increased. All other qualitative image parameters showed no significant differences for the administered activities, but they showed significant trends with increasing uptake time: less nonspecific blood activity, more frequent background uptake in the bone marrow, and increased negative impact on clinical decision making. Conclusion: The biodistribution of 18F-rhPSMA-7 was similar to that of established PSMA ligands, and tumor uptake of 18F-rhPSMA-7 was stable across the administered activities and uptake times. An early imaging time point (50-70 min) is recommended for 18F-rhPSMA-7 PET/CT to achieve the highest overall image quality.

Radiation Dosimetry and Biodistribution of 18F-PSMA-11 for PET Imaging of Prostate Cancer.

Prostate-specific membrane antigen (PSMA) is highly overexpressed in prostate cancer. Many PSMA analog radiotracers for PET/CT prostate cancer staging have been developed, such as 68Ga-PSMA-11. This radiotracer has achieved good results in multiple clinical trials, but because of the superior imaging characteristics of 18F-fluoride, 18F-PSMA-11 was developed. The aim of this study was to evaluate the administration safety and radiation dosimetry of 18F-PSMA-11. Methods: Six patients (aged 62-68 y; mean, 66 ± 2 y) with suspected prostate cancer recurrence after previous treatment were administered 2 MBq of 18F-PSMA-11 per kilogram of body weight and then underwent low-dose PET/CT imaging at 0, 20, 50, 90, and 300 min after injection. To evaluate the safety of administration, vital parameters were monitored. To assess toxicity, full blood count and biochemical parameters were determined. According to the latest International Commission on Radiological Protection recommendations, radiation dosimetry analysis was performed using IDAC-Dose 2.1. For blood activity measurement, small samples of venous blood were collected at various time points after injection. The unbound 18F-fluoride fraction was determined in plasma at 20, 50, and 90 min after administration to evaluate the defluorination rate of 18F-PSMA-11. Results: After injection, 18F-PSMA-11 cleared rapidly from the blood. At 5 h after injection, 29.0% ± 5.9% of the activity was excreted in urine. The free 18F fraction in plasma increased from 9.7% ± 1.0% 20 min after injection to 22.2% ± 1.5% 90 min after injection. The highest tracer uptake was observed in kidneys, bladder, spleen, and liver. No study drug-related adverse events were observed. The calculated mean effective dose was 12.8 ± 0.6 µSv/MBq. Conclusion:18F-PSMA-11 can be safely administered and results in a mean effective dose of 12.8 ± 0.6 µSv/MBq. Therefore, the total radiation dose is lower than for other PSMA PET agents and in the same range as 18F-DCFPyL.

Preclinical characterization of the novel HCV NS3 protease inhibitor GS-9256.

BACKGROUND: GS-9256 is an inhibitor of HCV NS3 protease with a macrocyclic structure and novel phosphinic acid pharmacophore. METHODS: Key preclinical properties of GS-9256 including in vitro antiviral activity, cross-resistance and pharmacokinetic properties were investigated in non-human species. RESULTS: In genotype (GT) 1b Huh-luc cells with a replicon encoding luciferase, GS-9256 had a mean 50% effective concentration (EC50) value of 20.0 nM, with minimal cytotoxicity. Antiviral activity was similar in a number of additional GT1b and GT1a replicon cell lines. Similar potency was observed in chimeric replicons encoding the NS3 protease of GT1 clinical isolates. GS-9256 was less active in GT2a replicon cells (14.2-fold increase in EC50). Additive to synergistic in vitro antiviral activity was observed when GS-9256 was combined with other agents including interferon-α, ribavirin, NS5B polymerase inhibitors GS-6620 and tegobuvir, as well as the NS5A inhibitor ledipasvir. GS-9256 retained wild-type activity against all tested NS5B and NS5A inhibitor resistance mutations. GS-9256 was metabolically stable in microsomes and hepatocytes of tested species, including rodents, dogs and humans. GS-9256 had high bioavailability in mice (near 100%) and moderate bioavailability in rats (14%), dogs (21%) and monkeys (14%). Elimination half-lives were approximately 2 h in mice, 0.6 h in rats, 5 h in dogs and 4 h in monkey. A study in bile duct-cannulated rats indicated that the major route of elimination is through biliary excretion of unmetabolized GS-9256. CONCLUSIONS: GS-9256 showed a favourable preclinical profile supportive of clinical development for the treatment of chronic HCV infection in GT1 patients.

Pharmacokinetics of butafosfan after intravenous and intramuscular administration in piglets.

The pharmacokinetics and bioavailability of butafosfan in piglets were investigated following intravenous and intramuscular administration at a single dose of 10 mg/kg body weight. Plasma concentration-time data and relevant parameters were best described by noncompartmental analysis after intravenous and intramuscular injection. The data were analyzed through WinNolin 6.3 software. After intravenous administration, the mean pharmacokinetic parameters were determined as T1/2λz of 3.30 h, Cl of 0.16 L kg/h, AUC of 64.49 ± 15.07 µg h/mL, Vss of 0.81 ± 0.44/kg, and MRT of 1.51 ± 0.27 h. Following intramuscular administration, the Cmax (28.11 µg/mL) was achieved at Tmax (0.31 h) with an absolute availability of 74.69%. Other major parameters including AUC and MRT were 48.29 ± 21.67 µg h/mL and 1.74 ± 0.29 h, respectively.

Comparative assessment of the environmental hazards of and exposure to perfluoroalkyl phosphonic and phosphinic acids (PFPAs and PFPiAs): Current knowledge, gaps, challenges and research needs.

Perfluoroalkyl phosphonic and phosphinic acids (PFPAs and PFPiAs) are sub-groups of per- and polyfluoroalkyl substances (PFASs) that have been commercialized since the 1970s, particularly as defoamers in pesticide formulations and wetting agents in consumer products. Recently, C4/C4 PFPiA and its derivatives have been presented as alternatives to long-chain PFASs in certain applications. In this study, we systematically assess the publicly available information on the hazardous properties, occurrence, and exposure routes of PFPAs and PFPiAs, and make comparisons to the corresponding properties of their better-known carboxylic and sulfonic acid analogs (i.e. PFCAs and PFSAs). This comparative assessment indicates that [i] PFPAs likely have high persistence and long-range transport potential; [ii] PFPiAs may transform to PFPAs (and possibly PFCAs) in the environment and biota; [iii] certain PFPAs and PFPiAs can only be slowly eliminated from rainbow trout and rats, similarly to long-chain PFCAs and PFSAs; [iv] PFPAs and PFPiAs have modes-of-action that are both similar to, and different from, those of PFCAs and PFSAs; and [v] the measured levels of PFPAs/PFPiAs in the global environment and biota appear to be low in comparison to PFCAs and PFSAs, suggesting, for the time being, low risks from PFPAs and PFPiAs alone. Although risks from individual PFPAs/PFPiAs are currently low, their ongoing production and use and high persistence will lead to increasing exposure and risks over time. Furthermore, simultaneous exposure to PFPAs, PFPiAs and other PFASs may result in additive effects necessitating cumulative risk assessments. To facilitate effective future research, we highlight possible strategies to overcome sampling and analytical challenges.

A shortcut to high-affinity Ga-68 and Cu-64 radiopharmaceuticals: one-pot click chemistry trimerisation on the TRAP platform.

Due to its 3 carbonic acid groups being available for bioconjugation, the TRAP chelator (1,4,7-triazacyclononane-1,4,7-tris(methylene(2-carboxyethylphosphinic acid))) is chosen for the synthesis of trimeric bioconjugates for radiolabelling. We optimized a protocol for bio-orthogonal TRAP conjugation via Cu(I)-catalyzed Huisgen-cycloaddition of terminal azides and alkynes (CuAAC), including a detailed investigation of kinetic properties of Cu(II)-TRAP complexes. TRAP building blocks for CuAAC, TRAP(alkyne)3 and TRAP(azide)3 were obtained by amide coupling of propargylamine/3-azidopropyl-1-amine, respectively. For Cu(II) complexes of neat and triply amide-functionalized TRAP, the equilibrium properties as well as pseudo-first-order Cu(II)-transchelation, using 10 to 30 eq. of NOTA and EDTA, were studied by UV-spectrophotometry. Dissociation of any Cu(II)-TRAP species was found to be independent on the nature or excess of a competing chelator, confirming a proton-driven two-step mechanism. The respective thermodynamic stability constants (log K(ML): 19.1 and 17.6) and dissociation rates (k: 38 × 10(-6) and 7 × 10(-6) s(-1), 298 K, pH 4) show that the Cu(II) complex of the TRAP-conjugate possesses lower thermodynamic stability but higher kinetic inertness. At pH 2-3, its demetallation with NOTA was complete within several hours/days at room temperature, respectively, enabling facile Cu(II) removal after click coupling by direct addition of NOTA trihydrochloride to the CuAAC reaction mixture. Notwithstanding this, an extrapolated dissociation half life of >100 h at 37 °C and pH 7 confirms the suitability of TRAP-bioconjugates for application in Cu-64 PET (cf. t(1/2)(Cu-64) = 12.7 h). To showcase advantages of the method, TRAP(DUPA-Pep)3, a trimer of the PSMA inhibitor DUPA-Pep, was synthesized using 1 eq. TRAP(alkyne)3, 3.3 eq. DUPA-Pep-azide, 10 eq. Na ascorbate, and 1.2 eq. Cu(II)-acetate. Its PSMA affinity (IC50), determined by the competition assay on LNCaP cells, was 18-times higher than that of the corresponding DOTAGA monomer (IC50: 2 ± 0.1 vs. 36 ± 4 nM), resulting in markedly improved contrast in Ga-68-PET imaging. In conclusion, the kinetic inertness profile of Cu(II)-TRAP conjugates allows for simple Cu(II) removal after click functionalisation by means of transchelation, but also confirms their suitability for Cu-64-PET as demonstrated previously (Dalton Trans., 2012, 41, 13803).

Dose-dependent effects of lesogaberan on reflux measures in patients with refractory gastroesophageal reflux disease: a randomized, placebo-controlled study.

BACKGROUND: The γ-aminobutyric acid type B-receptor agonist lesogaberan (AZD3355) has been developed for use in patients with gastroesophageal reflux disease (GERD) symptoms despite proton pump inhibitor (PPI) therapy (partial responders). This study aimed to explore the dose-response effect of lesogaberan on reflux episodes in partial responders. METHODS: In this randomized, single-centre, double-blind, crossover, placebo-controlled study, partial responders taking optimised PPI therapy were given 30, 90, 120 and 240 mg doses of lesogaberan. Each dose was given twice (12 h apart) during a 24-h period, during which impedance-pH measurements were taken. RESULTS: Twenty-five patients were included in the efficacy analysis and 27 in the safety analysis. The effect of lesogaberan on the mean number of reflux episodes was dose-dependent, and all doses significantly reduced the mean number of reflux episodes relative to placebo. Lesogaberan also dose-dependently reduced the mean number of acid reflux episodes (except the 30 mg dose) and weakly acid reflux episodes (all doses) significantly, relative to placebo. Regardless of dose, lesogaberan had a similar effect on the percentage of time with esophageal pH < 4 [mean reduction: 68.5% (30 mg), 54.2% (90 mg), 65.9% (120 mg), 72.1% (240 mg); p < 0.05 except 90 mg dose]. No adverse events led to discontinuation and no serious adverse events occurred during active treatment. CONCLUSIONS: Lesogaberan inhibited reflux in a dose-dependent manner in partial responders taking optimised PPI therapy, and these effects were significant versus placebo. All lesogaberan doses were well tolerated and were not associated with clinically relevant adverse events. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01043185.

Unexpected finding of delayed-onset seizures in HIV-positive, treatment-experienced subjects in the Phase IIb evaluation of fosdevirine (GSK2248761).

BACKGROUND: Fosdevirine (GSK2248761) is a non-nucleoside reverse transcriptase inhibitor with HIV-1 activity against common efavirenz-resistant strains. Two partially blind, randomized, Phase IIb studies were initiated (1 in treatment-naive and 1 in treatment-experienced subjects with HIV) to select a once-daily dose of fosdevirine for Phase III trials. METHODS: In the SIGNET study, treatment-naive subjects were randomized 1:1:1 to receive once-daily fosdevirine 100 or 200 mg or efavirenz 600 mg, each along with tenofovir disoproxil fumarate/emtricitabine 300 mg/200 mg or abacavir/lamivudine 600 mg/300 mg. In the SONNET study, treatment-experienced subjects with non-nucleoside reverse transcriptase inhibitor-resistant HIV-1 were randomized 1:1:1 to treatment with fosdevirine 100 or 200 mg once daily or etravirine 200 mg twice daily, each along with twice-daily darunavir/ritonavir 600/100 mg and raltegravir 400 mg. The primary efficacy end point was the proportion of subjects with HIV-1 RNA<50 copies/ml. Safety and pharmacokinetics were also addressed. RESULTS: A total of 35 subjects were exposed to fosdevirine 100 or 200 mg. Trials were halted when 5 treatment-experienced subjects (1 receiving fosdevirine 100 mg, 4 receiving fosdevirine 200 mg) developed new-onset seizures after ≥4 weeks of exposure to fosdevirine. There was no clear association between seizures and fosdevirine plasma drug levels. Time to seizure onset ranged from 28 to 81 days, and all 5 subjects experienced ≥1 seizure after drug discontinuation. CONCLUSIONS: The delayed onset of seizures after fosdevirine exposure and persistence after discontinuation is without precedent in antiretroviral drug development, leading to additional investigation and underscoring the need for careful subject monitoring.

Central nervous system disposition and metabolism of Fosdevirine (GSK2248761), a non-nucleoside reverse transcriptase inhibitor: an LC-MS and Matrix-assisted laser desorption/ionization imaging MS investigation into central nervous system toxicity.

The CNS disposition and metabolism of Fosdevirine (FDV), an HIV non-nucleoside reverse transcriptase inhibitor, was investigated in four patients who unexpectedly experienced seizures after at least 4 weeks of treatment in a Phase IIb, HIV-1 treatment experienced study. In addition, the CNS disposition and metabolism of FDV was examined in samples from rabbit, minipig, and monkey studies. LC-MS was used to characterize and estimate the concentrations of FDV and its metabolites in cerebral spinal fluid (seizure patients, rabbit, and monkey) and brain homogenate (rabbit, minipig, and monkey). The application of matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) provided the spatial distribution of FDV and its metabolites in brain tissue (rabbit, minipig, and monkey). A cysteine conjugate metabolite resulting from an initial glutathione (GSH) Michael addition to the trans-phenyl acrylonitrile moiety of FDV was the predominant drug-related component in the samples from seizure patients, rabbits, and minipigs. This metabolite persisted in the CNS for an extended period of time after the last dose in both seizure patients and minipigs. Furthermore, the localization of this metabolite was found to be highly associated with the white matter in rabbit and minipig brain sections by MALDI IMS. In contrast, the predominant component in monkey CNS was FDV, which was shown to be highly associated with the gray matter. On the basis of these data, several hypothesizes are considered, which might provide insights into species differences in CNS toxicity/seizures observed after FDV dosing.

Effect of food on the bioavailability of lesogaberan given as an oral solution or as modified-release capsules in healthy male volunteers.

The novel Type B gamma-aminobutyric acid (GABAB)-receptor agonist lesogaberan (AZD3355) has been evaluated as an add-on to proton pump inhibitor treatment for gastroesophageal reflux disease, but the effect of food on the bioavailability of this compound has not been assessed. In this openlabel crossover study, healthy males received single 100 mg doses of lesogaberan (oral solution (A) or oral modified release (MR) capsules with a dissolution rate of 50% (B) or 100% (C) over 4 h) with and without food. Blood plasma concentrations of lesogaberan were assessed over 48 h. A log-transformed geometric mean Cmax and AUC ratio within the 90% confidence interval (CI) range (0.80 - 1.25) was defined as excluding a clinically relevant food effect. Overall, 57 subjects completed the study. Only the oral lesogaberan solution had a fed/fasting Cmax ratio outside the 90% CI range (Cmax ratio: 0.76). AUC ratios were within the 90% CI limits for all three lesogaberan formulations. The only substantial change in tmax associated with food intake was observed for the oral solution (1.0 h without food, 1.8 h with food). In conclusion, a clinically relevant food effect could be excluded for the lesogaberan MR formulations, but not for the oral lesogaberan solution.

Drug interaction profile for GSK2248761, a next generation non-nucleoside reverse transcriptase inhibitor.

AIM: To evaluate potential drug interactions with antiretroviral therapies or supportive therapies for use in conjunction with the once daily, next generation non-nucleoside reverse transcriptase inhibitor GSK2248761 in patients with HIV-1 infection. METHODS: A series of phase I drug interaction studies was conducted. RESULTS: GSK2248761 was shown to be a weak CYP3A4 and CYP2D6 inhibitor in a clinical study with a probe cocktail. Mean plasma concentration-time profiles for atazanavir, tenofovir disoproxil fumarate/emtricitabine (TDF/FTC), darunavir (DRV, administered with ritonavir [RTV]), and drospirenone/ethinylestradiol were similar following co-administration of GSK2248761. Plasma raltegravir AUC(0,τ) and C(max) increased by 18% with no change in Cτ when raltegravir was co-administered with GSK2248761. Lopinavir (LPV) plasma AUC(0,τ), C(max) and Cτ decreased by 23%, 14% and 40%, respectively, following administration of lopinavir/ritonavir with GSK2248761. Atorvastatin, rosuvastatin and simvastatin AUC(0,∞) and C(max) increased following co-administration with GSK2248761, with the largest changes observed for simvastatin (3.7-fold and 4.3-fold). Changes in maximum and extent of GSK2248761 exposure were marginal after co-administration with atazanavir, TDF/FTC and raltegravir compared with GSK2248761 administered alone. Co-administration of GSK2248761 with DRV/RTV and LPV/RTV increased plasma GSK2248761 exposures by 1.25- to ≤2-fold compared with GSK2248761 administered alone, and increases in GSK2248761 exposure were higher following single dose co-administration of DRV/RTV or LPV/RTV compared with multiple doses. There were few drug-related AEs, and no treatment-related trends in blood chemistry, haematology, urinalysis, vital signs or ECG findings. CONCLUSIONS: These studies indicate that GSK2248761 was safe and well tolerated in healthy adults treated in these studies at the doses and duration of therapy evaluated.

Dietary bioaccumulation of perfluorophosphonates and perfluorophosphinates in juvenile rainbow trout: evidence of metabolism of perfluorophosphinates.

The perfluorophosphonates (PFPAs) and perfluorophosphinates (PFPiAs) are high production volume chemicals that have been observed in Canadian surface waters and wastewater environments. To examine whether their occurrence would result in contamination of organisms in aquatic ecosystems, juvenile rainbow trout (Oncorhynchus mykiss) were separately exposed to a mixture of C6, C8, and C10 monoalkylated PFPAs and a mixture of C6/C6, C6/C8, and C8/C8 dialkylated PFPiAs in the diet for 31 days, followed by 32 days of depuration. Tissue distribution indicated preferential partitioning to blood and liver. Depuration half-lives ranged from 3 to 43 days and increased with the number of perfluorinated carbons present in the chemical. The assimilation efficiencies (α, 7-34%) and biomagnification factors (BMFs, 0.007-0.189) calculated here for PFPAs and PFPiAs were lower than those previously observed for the perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs) in the same test organism. Bioaccumulation was observed to decreased in the order of PFSAs > PFCAs > PFPAs of equal perfluorocarbon chain length and was dependent on the charge of the polar headgroup. Bioaccumulation of the PFPiAs was observed to be low due to their rapid elimination via metabolism to the corresponding PFPAs. Here, we report the first observation of an in vivo cleavage of the carbon-phosphorus bond in fish, as well as, the first in vivo biotransformation of a perfluoroalkyl acid (PFAA). As was previously observed for PFCAs and PFSAs, none of the BMFs determined here for the PFPAs and PFPiAs were greater than one, which suggests PFAAs do not biomagnify from dietary exposure in juvenile rainbow trout.

Pharmacokinetic profile of lesogaberan (AZD3355) in healthy subjects: a novel GABA(B)-receptor agonist reflux inhibitor.

BACKGROUND: Lesogaberan (AZD3355) is a novel reflux inhibitor developed as an add-on treatment to proton pump inhibitors (PPIs) for symptom relief in patients with gastroesophageal reflux disease who have a partial response to PPI therapy. OBJECTIVE: The aim of this study was to evaluate the pharmacokinetic profile of lesogaberan in healthy subjects after single oral and intravenous administration of (14)C-labeled lesogaberan and non-(14)C-labeled lesogaberan. STUDY DESIGN: This was an open-label, single-center, randomized, two-way crossover, phase I study. PARTICIPANTS: Ten healthy male subjects took part in the study. INTERVENTION: Volunteers were randomized to receive a single dose of either orally dosed (100 mg) or intravenously infused (20 mg) non-(14)C-labeled lesogaberan, and then orally (100 mg) or intravenously (20 mg) administered (14)C-labeled lesogaberan in a crossover design. Treatment periods were separated by a washout period of at least 7 days. MAIN OUTCOME MEASURES: Analyses of the rate and route of excretion, dose recovery, area under the plasma concentration versus time curve (AUC), AUC to the last quantifiable concentration, maximal plasma concentration (C(max)), time to C(max), the apparent elimination half-life, bioavailability, total clearance, renal clearance, fraction of the bioavailable dose excreted unchanged in the urine, cumulative amount of drug excreted unchanged in urine, and the apparent volume of distribution at steady state of lesogaberan. RESULTS: Lesogaberan was rapidly and extensively absorbed from the gastrointestinal tract and C(max) was achieved within 1-2 hours of oral dosing. The terminal half-life of lesogaberan was between 11 and 13 hours. Renal clearance accounted for approximately 22% of total body clearance. Based on the recovery of administered radioactivity, approximately 84% of the dose was excreted into the urine either as the parent compound or as water-soluble metabolite(s). There were no safety concerns raised during the study. CONCLUSION: Orally administered lesogaberan is rapidly absorbed with high bioavailability and the majority of the dose is excreted by the kidneys either as the parent compound or as metabolites. The major elimination pathway for lesogaberan in man is metabolism.

Synthesis and biological evaluation of aryl-phospho-indole as novel HIV-1 non-nucleoside reverse transcriptase inhibitors.

A novel series of 3-aryl-phospho-indole (API) non-nucleoside reverse transcriptase inhibitors of HIV-1 was developed. Chemical variation in the phosphorus linker led to the discovery of 3-phenyl-methyl-phosphinate-2-carboxamide 14, which possessed excellent potency against wild-type HIV-1 as well as viruses bearing K103N and Y181C single mutants in the reverse transcriptase gene. Chiral separation of the enantiomers showed that only R enantiomer retained the activity. The pharmacokinetic, solubility, and metabolic properties of 14 were assessed.

Evaluation of the pharmacokinetic interaction between lesogaberan (AZD3355) and esomeprazole in healthy subjects.

BACKGROUND: Transient lower esophageal sphincter relaxations (TLESRs) have been identified as a primary cause of reflux events in patients with gastroesophageal reflux disease (GERD). GABA(B) receptor agonists such as lesogaberan (AZD3355) have been shown to inhibit TLESRs in healthy subjects and patients with GERD, and, therefore, offer a novel therapeutic add-on strategy to acid suppression for the management of GERD. As lesogaberan is being developed as an add-on treatment for the management of patients with GERD who have a partial response to proton pump inhibitor (PPI) therapy, it is important to rule out any clinically important pharmacokinetic drug-drug interaction between lesogaberan and PPIs. OBJECTIVE: To evaluate the effect of esomeprazole on the pharmacokinetics and safety of lesogaberan and vice versa. STUDY DESIGN: This was an open-label, randomized, three-way crossover study. The study was open to healthy adult male and female subjects. The study subjects received treatment with, in random order, lesogaberan (150 mg twice daily [dose interval 12 hours]), esomeprazole (40 mg once daily), and a combination of both, during 7-day treatment periods. MAIN OUTCOME: The presence or absence of pharmacokinetic interactions between lesogaberan and esomeprazole was assessed by measuring the steady-state area under the plasma concentration-time curves during the dosing interval (AUC(τ)) and the maximum observed plasma concentration (C(max)) for lesogaberan and esomeprazole. RESULTS: Thirty male subjects (mean age 23.2 years, 97% Caucasian) were randomized to treatment and 28 subjects completed the study (one subject was lost to follow-up, and one subject discontinued due to an adverse event). The 95% confidence intervals of the geometric mean ratios for AUC(τ) and C(max) of lesogaberan and esomeprazole administered alone and concomitantly were within the recognized boundaries of bioequivalence (0.8-1.25). No new safety concerns were raised during this study. The number of patients with adverse events during treatment with lesogaberan alone (n = 17) and concomitantly with esomeprazole (n = 18) were comparable but higher than with esomeprazole alone (n = 10). Paresthesia (episodic, mild, and transient), pharyngitis, and flatulence were the most frequently reported adverse events. CONCLUSIONS: There was no observed pharmacokinetic interaction between lesogaberan and esomeprazole when concomitantly administered to healthy subjects, and concomitant therapy was well tolerated. TRIAL REGISTRATION NUMBER (clinicaltrials.gov): NCT00684190.

Effect of lesogaberan, a novel GABA(B)-receptor agonist, on transient lower oesophageal sphincter relaxations in male subjects.

BACKGROUND: Transient lower oesophageal sphincter relaxations (TLESRs) are a major mechanism behind gastro-oesophageal reflux disease (GERD). AIM: To assess the effect of lesogaberan (AZD3355) - a novel peripherally active GABA(B) receptor agonist - on TLESRs. METHODS: Twenty-four healthy men were enrolled in this single-blind, placebo-controlled, randomized, single-centre, three-period crossover phase 1 study. Subjects were randomized to receive single oral doses of lesogaberan (0.8 mg/kg), baclofen (40 mg) and placebo, separated by washout periods of < or = 7 days. Subjects finished a meal 1 h after the dose. Oesophageal manometry and pH-metry measurements were taken during the 3 h after the meal. RESULTS: Twenty-one subjects completed the study. Compared with placebo, lesogaberan 0.8 mg/kg significantly reduced the number of TLESRs by 36% [geometric mean ratio (GMR): 0.64; 95% confidence interval (CI): 0.51-0.82] and significantly reduced the number of acid reflux episodes (mean reduction: 1.6; 95% CI: 0.34-2.9). Lesogaberan also significantly increased lower oesophageal sphincter (LES) pressure by 39% compared with placebo (GMR: 1.39; 95% CI: 1.18-1.64). Comparable results were observed with baclofen. Similar numbers of adverse events were reported by subjects taking lesogaberan and placebo. CONCLUSION: Compared with placebo, lesogaberan significantly reduced TLESRs and acid reflux episodes and increased LES pressure.

IDX-899, an aryl phosphinate-indole non-nucleoside reverse transcriptase inhibitor for the potential treatment of HIV infection.

Antiretroviral drug resistance is one of the complications of highly active antiretroviral therapy (HAART). Second-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs) are being developed for use in patients infected with HIV-1 because of the enhanced activity of these inhibitors against viruses that are resistant to the first-generation NNRTIs. IDX-899 (GSK-2248761), under development by Idenix Pharmaceuticals Inc and ViiV Healthcare, is an aryl phosphinate-indole second-generation NNRTI that potently and selectively inhibits wild-type and NNRTI-resistant HIV-1 in vitro. Preclinical data for IDX-899 suggest a significantly greater barrier to resistance compared with that of the first-generation NNRTI efavirenz. Two pathways of resistance have been identified for IDX-899 in vitro that include Glu138Lys and Val90Ile/Tyr181Cys mutations. Pharmacokinetic studies demonstrated that IDX-899 exhibits linear, dose-proportional and food-dependent pharmacokinetics; Cmin concentrations achieved with this drug allow once-daily dosing. In phase I clinical trials, IDX-899 reduced HIV-1 RNA and increased CD4+ cell counts in treatment-naïve patients infected with HIV-1. At the time of publication, a phase II clinical trial of IDX-899 was being conducted.

Microdose pharmacokinetics of IDX899 and IDX989, candidate HIV-1 non-nucleoside reverse transcriptase inhibitors, following oral and intravenous administration in healthy male subjects.

IDX899 and IDX989 are new non-nucleoside reverse-transcriptase inhibitors (NNRTIs) that exhibit potent inhibition of HIV-1 replication, including NNRTI-resistant mutants. This microdose study investigates the pharmacokinetics and determined oral bioavailability. For each compound, 4 healthy male subjects are randomized to receive via a crossover design a single 100-microg oral and intravenous dose together with 100 nCi of [(14)C]-labeled drug. Plasma and urine samples are obtained over a period of 168 hours postdose and analyzed for total, unchanged drug and major metabolites using an accelerator mass spectrometry method. Based on total radioactivity, oral absorption is near complete. For the parent drug, mean absolute bioavailability is 61% and 65% for IDX899 and IDX989, respectively. Both compounds are extensively metabolized especially after oral dosing. Observed terminal phase half-lives after oral and intravenous doses range from 4 to 10 hours and are comparable for the 2 compounds. Urine excretion of radioactivity for both compounds is less than 10%. These data show for the first time that IDX899 and IDX989 possess favorable pharmacokinetic properties in humans, including high mean absolute bioavailability and long half-life. IDX899 has been selected based on these initial pharmacokinetic assessments and other criteria as the candidate for further clinical development.

Single-dose escalation and multiple-dose safety, tolerability, and pharmacokinetics of IDX899, a candidate human immunodeficiency virus type 1 nonnucleoside reverse transcriptase inhibitor, in healthy subjects.

IDX899 is a novel nonnucleoside reverse transcriptase inhibitor (NNRTI) with potent in vitro activity against wild-type and NNRTI-resistant strains of human immunodeficiency virus type 1 (HIV-1) and with a high genetic barrier to resistance. Single rising doses of 50 and 100 (given by use of a 50-mg capsule) and 200, 400, 800, and 1,200 mg (given by use of a 200-mg capsule) of IDX899 or matching placebo were administered sequentially to cohorts of healthy male subjects, followed by the administration of multiple doses of 800 mg once daily (QD) or 400 mg twice daily (BID) for 7 days. A single dose of 400 mg was also administered to a cohort of females. IDX899 was administered orally under fasted (50- to 400-mg doses) and then fed (> or = 200-mg doses) conditions. Exposure to IDX899 was dose proportional and comparable in males and females. With a different drug-to-excipient ratio, the 50-mg capsule led to a higher exposure but a shorter mean terminal half-life (t(1/2)) of 6.2 to 6.8 h. The 200-mg capsule resulted in a more sustained exposure with a longer mean t(1/2) of 7.9 to 14.6 h. Food enhanced absorption by approximately twofold, while it delayed the time to the maximum concentration. The mean concentration at 24 h following the administration of a single 200-mg dose under fed conditions exceeded the in vitro protein binding-adjusted 90% inhibitory concentration by fourfold. The levels of plasma exposure were similar between the single dosing and the repeat dosing with 800 mg QD and was approximately twofold higher with 400 mg BID. Mean steady-state trough levels were 0.9 microg/ml (range, 0.2 to 2.5 microg/ml) and 2.1 microg/ml (range, 0.5 to 4.5 microg/ml) for the 800-mg QD and 400-mg BID regimens, respectively. The level of excretion of unchanged drug in urine was negligible. IDX899 was well tolerated; and no serious adverse events, dose-dependent adverse events, or laboratory abnormalities were detected. These favorable safety and pharmacokinetic results support further clinical studies with patients with HIV-1 infection by the use of a QD regimen.