Biomarker-assisted dose selection for safety and efficacy in early development of PNU-100480 for tuberculosis.

Tuberculosis is a serious global health threat for which new treatments are urgently needed. This study examined the safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple ascending doses of the oxazolidinone PNU-100480 in healthy volunteers, using biomarkers for safety and efficacy. Subjects were randomly assigned to PNU-100480 or placebo (4:1) at schedules of 100, 300, or 600 mg twice daily or 1,200 mg daily for 14 days or a schedule of 600 mg twice daily for 28 days to which pyrazinamide was added on days 27 and 28. A sixth cohort was given linezolid at 300 mg daily for 4 days. Signs, symptoms, and routine safety tests were monitored. Bactericidal activity against Mycobacterium tuberculosis was measured in ex vivo whole-blood culture. Plasma drug and metabolite concentrations were compared to the levels required for inhibition of M. tuberculosis growth and 50% inhibition of mitochondrial protein synthesis. All doses were safe and well tolerated. There were no hematologic or other safety signals during 28 days of dosing at 600 mg twice daily. Plasma concentrations of PNU-100480 and metabolites at this dose remained below those required for 50% inhibition of mitochondrial protein synthesis. Cumulative whole-blood bactericidal activity of PNU-100480 at this dose (-0.316 ± 0.04 log) was superior to the activities of all other doses tested (P < 0.001) and was significantly augmented by pyrazinamide (-0.420 ± 0.06 log) (P = 0.002). In conclusion, PNU-100480 was safe and well tolerated at all tested doses. Further studies in patients with tuberculosis are warranted. Biomarkers can accelerate early development of new tuberculosis treatments.

Pharmacokinetics and whole-blood bactericidal activity against Mycobacterium tuberculosis of single doses of PNU-100480 in healthy volunteers.

BACKGROUND: The oxazolidinone PNU-100480 is superior to linezolid against experimental murine tuberculosis. Two metabolites contribute to but do not fully account for its superiority. This study examined the safety, tolerability, pharmacokinetics, and mycobactericidal activity of single ascending doses of PNU-100480. METHODS: Nineteen healthy volunteers received 2 escalating single oral doses (35-1500 mg) of PNU-100480 or placebo. Eight subjects received 4 daily doses of 300 mg of linezolid. Drug concentrations and bactericidal activity against Mycobacterium tuberculosis in whole-blood bactericidal culture were measured. RESULTS: All doses were safe and well tolerated. PNU-100480 doses to 1000 mg were well absorbed and showed approximately proportional increases in exposures of parent and metabolites. The geometric mean maximal concentrations of PNU-100480, PNU-101603, and PNU-101244 (sulfoxide and sulfone metabolites) at 1000 mg were 839, 3558, and 54 ng/mL, respectively. The maximal whole-blood bactericidal activity (-0.37 +/- .06 log/day) occurred at combined PNU levels > or =2 times the minimum inhibitory concentration. The observed geometric mean maximal concentration for linezolid was 6425 ng/mL. Its maximal whole-blood bactericidal activity also occurred at > or =2 times the minimum inhibitory concentration, but it was only -0.16 +/- .05 log/day (P< .001) Neither drug showed enhanced activity at higher concentrations. CONCLUSIONS: Single doses of PNU-100480 to 1000 mg were well tolerated and exhibited antimycobacterial activity superior to 300 mg of linezolid at steady state. Additional studies are warranted to define its role in drug-resistant tuberculosis.

Human sebum requires de novo lipogenesis, which is increased in acne vulgaris and suppressed by acetyl-CoA carboxylase inhibition.

Sebum plays important physiological roles in human skin. Excess sebum production contributes to the pathogenesis of acne vulgaris, and suppression of sebum production reduces acne incidence and severity. We demonstrate that sebum production in humans depends on local flux through the de novo lipogenesis (DNL) pathway within the sebocyte. About 80 to 85% of sebum palmitate (16:0) and sapienate (16:1n10) were derived from DNL, based on stable isotope labeling, much higher than the contribution of DNL to triglyceride palmitate in circulation (~20%), indicating a minor contribution by nonskin sources to sebum lipids. This dependence on local sebocyte DNL was not recapitulated in two widely used animal models of sebum production, Syrian hamsters and Göttingen minipigs. Confirming the importance of DNL for human sebum production, an acetyl-CoA carboxylase inhibitor, ACCi-1, dose-dependently suppressed DNL and blocked synthesis of fatty acids, triglycerides, and wax esters but not free sterols in human sebocytes in vitro. ACCi-1 dose-dependently suppressed facial sebum excretion by ~50% (placebo adjusted) in human individuals dosed orally for 2 weeks. Sebum triglycerides, wax esters, and free fatty acids were suppressed by ~66%, whereas non-DNL-dependent lipid species, cholesterol, and squalene were not reduced, confirming selective modulation of DNL-dependent lipids. Last, individuals with acne vulgaris exhibited increased sebum production rates relative to individuals with normal skin, with >80% of palmitate and sapienate derived from DNL. These findings highlight the importance of local sebocyte DNL for human skin sebaceous gland biology and illuminate a potentially exploitable therapeutic target for the treatment of acne vulgaris.

In vitro microbiological characterization of a novel azalide, two triamilides and an azalide ketal against bovine and porcine respiratory pathogens.

Several novel 15-membered-ring macrolide agents (azalide 1, triamilides 2 and 3, and the azalide 3,6-ketal 4) were identified as potential antibacterial agents against Mannheimia (formerly named as Pasteurella) haemolytica, Pasteurella multocida, Haemophilus somnus and Actinobacillus pleuropneumoniae, important etiological agents of bovine and porcine respiratory disease. Compound 3 is the major component of the antibiotic tulathromycin. Antibacterial activity against tilmicosin-resistant P. multocida field isolates was also tested. In vitro MIC 50/90 analysis revealed that the four newly synthesized compounds were more potent than tilmicosin against M. haemolytica (4 to approximately 8x), P. multocida (8 to approximately 16x), A. pleuropneumoniae (4x), H. somnus (2x and 16x), and tilmicosin-resistant P. multocida (32x). In time-kill kinetic studies, all four novel compounds and tilmicosin showed bactericidal activity against M. haemolytica, P. multocida and A. pleuropneumoniae at both 4x and 8x MIC. A functional assay using genetically defined mutants revealed that all four novel compounds were poorer substrates for the efflux pump, AcrA/B system, than tilmicosin. A pH study using LPS mutants indicated that the enhanced in vitro potency of the triamilides, particularly compound 3 was mainly due to better penetration of the molecule through the outer membrane. The third amine group at the C-4'' position of the triamilde molecules contributed to this increased membrane penetration by increasing overall basicity. These studies indicate that the four novel compounds have potential as antibacterial agents against bovine and porcine respiratory disease.

Mycobactericidal activity of sutezolid (PNU-100480) in sputum (EBA) and blood (WBA) of patients with pulmonary tuberculosis.

RATIONALE: Sutezolid (PNU-100480) is a linezolid analog with superior bactericidal activity against Mycobacterium tuberculosis in the hollow fiber, whole blood and mouse models. Like linezolid, it is unaffected by mutations conferring resistance to standard TB drugs. This study of sutezolid is its first in tuberculosis patients. METHODS: Sputum smear positive tuberculosis patients were randomly assigned to sutezolid 600 mg BID (N = 25) or 1200 mg QD (N = 25), or standard 4-drug therapy (N = 9) for the first 14 days of treatment. Effects on mycobacterial burden in sputum (early bactericidal activity or EBA) were monitored as colony counts on agar and time to positivity in automated liquid culture. Bactericidal activity was also measured in ex vivo whole blood cultures (whole blood bactericidal activity or WBA) inoculated with M. tuberculosis H37Rv. RESULTS: All patients completed assigned treatments and began subsequent standard TB treatment according to protocol. The 90% confidence intervals (CI) for bactericidal activity in sputum over the 14 day interval excluded zero for all treatments and both monitoring methods, as did those for cumulative WBA. There were no treatment-related serious adverse events, premature discontinuations, or dose reductions due to laboratory abnormalities. There was no effect on the QT interval. Seven sutezolid-treated patients (14%) had transient, asymptomatic ALT elevations to 173±34 U/L on day 14 that subsequently normalized promptly; none met Hy's criteria for serious liver injury. CONCLUSIONS: The mycobactericidal activity of sutezolid 600 mg BID or 1200 mg QD was readily detected in sputum and blood. Both schedules were generally safe and well tolerated. Further studies of sutezolid in tuberculosis treatment are warranted. TRIAL REGISTRATION: ClinicalTrials.gov NCT01225640.

Rapid evaluation in whole blood culture of regimens for XDR-TB containing PNU-100480 (sutezolid), TMC207, PA-824, SQ109, and pyrazinamide.

There presently is no rapid method to assess the bactericidal activity of new regimens for tuberculosis. This study examined PNU-100480, TMC207, PA-824, SQ109, and pyrazinamide, singly and in various combinations, against intracellular M. tuberculosis, using whole blood culture (WBA). The addition of 1,25-dihydroxy vitamin D facilitated detection of the activity of TMC207 in the 3-day cultures. Pyrazinamide failed to show significant activity against a PZA-resistant strain (M. bovis BCG), and was not further considered. Low, mid, and high therapeutic concentrations of each remaining drug were tested individually and in a paired checkerboard fashion. Observed bactericidal activity was compared to that predicted by the sum of the effects of individual drugs. Combinations of PNU-100480, TMC207, and SQ109 were fully additive, whereas those including PA-824 were less than additive or antagonistic. The cumulative activities of 2, 3, and 4 drug combinations were predicted based on the observed concentration-activity relationship, published pharmacokinetic data, and, for PNU-100480, published WBA data after oral dosing. The most active regimens, including PNU-100480, TMC207, and SQ109, were predicted to have cumulative activity comparable to standard TB therapy. Further testing of regimens including these compounds is warranted. Measurement of whole blood bactericidal activity can accelerate the development of novel TB regimens.

Synthesis and SAR of heteroaryl-phenyl-substituted pyrazole derivatives as highly selective and potent canine COX-2 inhibitors.

The discovery of heteroaryl-phenyl-substituted pyrazole derivatives as canine selective COX-2 inhibitors is described. Structure-activity relationship (SAR) studies of this class of compounds led to the identification of compound 1 which demonstrated a canine whole blood COX-2 inhibitory IC50 of 12 nM and selectivity ratio of COX-1/COX-2 greater than 4000-fold.

5-Heteroatom-substituted pyrazoles as canine COX-2 inhibitors: Part 2. Structure-activity relationship studies of 5-alkylethers and 5-thioethers.

Structure-activity relationship (SAR) studies of novel 2-[3-trifluoromethyl-5-alkyl(thio)ether pyrazo-1-yl]-5-methanesulfonyl pyridine derivatives for canine COX enzymes are described. The 4-cyano-5-alkyl ethers were found to have excellent potency and selectivity, whereas the 5-thioethers were potent but less selective than the ether analogs in a canine whole blood (CWB) COX-2 assay.

5-heteroatom substituted pyrazoles as canine COX-2 inhibitors. Part 1: Structure-activity relationship studies of 5-alkylamino pyrazoles and discovery of a potent, selective, and orally active analog.

Structure-activity relationship (SAR) studies of the novel 2-[3-di and trifluoromethyl-5-alkylamino pyrazo-1-yl]-5-methanesulfonyl (SO(2)Me)/sulfamoyl (SO(2)NH(2))-pyridine derivatives for canine COX enzymes are described. The studies led to the identification of 2e as lead with potent in vitro activity, selectivity, and in vivo activity in dogs and cats.

Discovery of a potent, selective and orally active canine COX-2 inhibitor, 2-(3-difluoromethyl-5-phenyl-pyrazol-1-yl)-5-methanesulfonyl-pyridine.

Structure-activity relationship (SAR) studies of 2-[3-di(and tri)fluoromethyl-5-arylpyrazol-1-yl]-5-methanesulfonylpyridine derivatives for canine COX enzymes are described. This led to the identification of 12a as a lead candidate for further progression. The in vitro and in vivo activity of 12a for the canine COX-2 enzyme as well as its in vivo efficacy and pharmacokinetic properties in dog are highlighted.