Phase 2, Randomized, Double-Blind, Dose-Ranging Study Evaluating the Safety, Tolerability, Population Pharmacokinetics, and Efficacy of Oral Torezolid Phosphate in Patients with Complicated Skin and Skin Structure Infections

Trius Therapeutics, Inc., 6310 Nancy Ridge Drive, Suite 105, San Diego, CA 92121, USA.
Antimicrobial Agents and Chemotherapy (Impact Factor: 4.48). 02/2011; 55(2):583-92. DOI: 10.1128/AAC.00076-10
Source: PubMed


Torezolid (TR-700) is the active moiety of the prodrug torezolid phosphate ([TP] TR-701), a second-generation oxazolidinone with 4- to 16-fold greater potency than linezolid against Gram-positive species including methicillin-resistant Staphylococcus aureus (MRSA). A double-blind phase 2 study evaluated three levels (200, 300, or 400 mg) of oral, once-daily TP over 5 to 7 days for complicated skin and skin structure infections (cSSSI). Patients 18 to 75 years old with cSSSI caused by suspected or confirmed Gram-positive pathogens were randomized 1:1:1. Of 188 treated patients, 76.6% had abscesses, 17.6% had extensive cellulitis, and 5.9% had wound infections. S. aureus, the most common pathogen, was isolated in 90.3% of patients (139/154) with a baseline pathogen; 80.6% were MRSA. Cure rates in clinically evaluable patients were 98.2% at 200 mg, 94.4% at 300 mg, and 94.4% at 400 mg. Cure rates were consistent across diagnoses, regardless of lesion size or the presence of systemic signs of infection. Clinical cure rates in patients with S. aureus isolated at baseline were 96.6% overall and 96.8% for MRSA. TP was safe and well tolerated at all dose levels. No patients discontinued treatment due to an adverse event. Three-stage hierarchical population pharmacokinetic modeling yielded a geometric mean clearance of 8.28 liters/h (between-patient variability, 32.3%), a volume of the central compartment of 71.4 liters (24.0%), and a volume of the peripheral compartment of 27.9 liters (35.7%). Results of this study show a high degree of efficacy at all three dose levels without significant differences in the safety profile and support the continued evaluation of TP for the treatment of cSSSI in phase 3 trials.

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Available from: Philippe Prokocimer, Jun 22, 2014
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    • "For all study subjects , there were no statistically significant differences seen between any of the tested doses regardless of lesion type, lesion size, and severity of infection. This result was true in both the modified intent-to-treat and the clinically evaluable populations , and it was seen at both end-of-therapy (EOT) and test-of-cure (TOC) visit (7 to 14 days post treatment) endpoints [41]. Since all doses were administered on a daily basis, the clinical trial validates the preclinical findings that support once-daily dosing, as well as the dose choice based on the nonneutropenic infection model studies. "
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    ABSTRACT: In the Staphylococcus aureus neutropenic murine thigh-infection model, the ratio of the free area under the 24-hour concentration-time curve to the minimum inhibitory concentration (fAUC/MIC) was found to be the pharmacodynamic index most closely linked to bacterial effect, with a ratio of approximately 50 producing a static effect. Further work was undertaken in neutropenic versus non-neutropenic animals. The presence of granulocytes increased the activity of tedizolid considerably, 25-fold on average, and maximal effect was achieved at an exposure equivalent to approximately 200 mg tedizolid phosphate per day in humans (dosing regimen used in phase 2 and 3 clinical trials). The fAUC/MIC was also found to be the pharmacodynamically linked variable in the S. aureus neutropenic murine pneumonia model; the fAUC/MIC ratio required for a static effect was approximately 20. Pharmacokinetic (PK) data demonstrate that tedizolid penetrates well into the epithelial lining fluid (ELF) of the lung. Data from the pneumonia infection model and ELF penetration PK study support exploring its use in pneumonia.
    Preview · Article · Jan 2014 · Clinical Infectious Diseases
    • "MRSA and MSSA strains also show 16 times lower frequency of spontaneous resistance as compared to strains exposed to linezolid. Torezolid has undergone phase II clinical trials for complicated skin and soft tissue infections with good efficacy and an acceptable side effect profile.[8] Its mean half-life of 8-11.1 h is approximately two-fold longer than that of linezolid, thus allowing once-daily dosing.[9] "
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    ABSTRACT: In order to deal with the rising problem of antibiotic resistance, newer antibacterials are being discovered and added to existing pool. Since the year 2000, however, only four new classes of antibacterials have been discovered. These include the oxazolidinones, glycolipopeptides, glycolipodepepsipeptide and pleuromutilins. Newer drugs were added to existing classes of antibiotics, such as streptogramins, quinolones, beta-lactam antibiotics, and macrolide-, tetracycline- and trimethoprim-related drugs. Most of the antibacterials are directed against resistant S. aureus infections, with very few against resistant gram-negative infections. The following article reviews the antibacterials approved by the FDA after the year 2000 as well as some of those in clinical trials. Data was obtained through a literature search via Pubmed and google as well as a detailed search of our library database.
    No preview · Article · Nov 2012 · North American Journal of Medical Sciences
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    • "A 600 mg dose was selected as early dosing estimates projected that it could be in the range of the therapeutic dose for the treatment of skin infections. However, results of a recent Phase 2 study showed a high degree of efficacy at lower doses [19] "
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    ABSTRACT: Plasma concentrations of antimicrobial drugs have long been used to correlate exposure with effect, yet one cannot always assume that unbound plasma and tissue concentrations are similar. Knowledge about unbound tissue concentrations is important in the development of antimicrobial drugs, since most infections are localised in tissues. Therefore, a clinical microdialysis study was conducted to evaluate the distribution of tedizolid (TR-700), the active moiety of the antimicrobial prodrug tedizolid phosphate (TR-701), into interstitial fluid (ISF) of subcutaneous adipose and skeletal muscle tissues following a single oral 600 mg dose of tedizolid phosphate in fasting conditions. Twelve healthy adult subjects were enrolled. Two microdialysis probes were implanted into the thigh of each subject, one into the vastus medialis muscle and one into subcutaneous adipose tissue. Probes were calibrated using retrodialysis. Dialysate samples were collected every 20 min for 12h following a single oral dose of 600 mg tedizolid phosphate, and blood samples were drawn over 24h. Unbound tedizolid levels in plasma were similar to those in muscle and adipose tissue. The ratios of unbound (free) AUC in tissues over unbound AUC in plasma (fAUC(tissue)/fAUC(plasma)) were 1.1 ± 0.2 and 1.2 ± 0.2 for adipose and muscle tissue, respectively. The median half-life was 8.1, 9.2 and 9.6h for plasma, adipose tissue and muscle tissue, respectively. Mean protein binding was 87.2 ± 1.8%. The study drug was very well tolerated. The results of this study show that tedizolid distributes well into ISF of adipose and muscle tissues. Unbound levels of tedizolid in plasma, adipose tissue and muscle tissue were well correlated. Free plasma levels are indicative of unbound levels in the ISF of muscle and adipose tissues.
    Full-text · Article · May 2012 · International journal of antimicrobial agents
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