Abla A. Creasey

Assessment of the safety of recombinant tissue factor pathway inhibitor in patients with severe sepsis: a multicenter, randomized, placebo-controlled, single-blind, dose escalation study.

Objective To identify a safe and potentially effective recombinant tissue factor pathway inhibitor (rTFPI) dose for further clinical evaluation in patients with severe sepsis. Design Prospective, randomized, single-blind, placebo-controlled, dose escalation, multicenter, multinational phase II clinical trial. Setting Thirty-eight intensive care units in the United States and Europe. Patients Two hundred and ten subjects with severe sepsis who received standard supportive care and antimicrobial therapy. Interventions Subjects received a continuous intravenous infusion of placebo or rTFPI at 0.025 or 0.05 mg/kg/hr for 4 days (96 hrs). Measurements and Main Results There were no significant imbalances in demographics, severity of illness, or source of infection in patients randomized to placebo or either dose of rTFPI. A 20% relative reduction in 28-day all-cause mortality was observed when all rTFPI-treated patients were compared with all placebo patients. An improvement in pulmonary organ dysfunction score and in a composite intensive care unit score (pulmonary, cardiovascular, and coagulation) were also noted in the rTFPI-treated patients. Logistic regression modeling indicated a substantial treatment by baseline laboratory international normalized ratio (INR) interaction effect when only treatment and INR were in the model (p = .037) and when baseline Acute Physiology and Chronic Health Evaluation (APACHE II) and log10 interleukin 6 were adjusted for (p = .026). This interaction effect indicates that higher baseline INR is associated with a more pronounced beneficial rTFPI effect. There was no increase in mortality in subjects treated with either dose of rTFPI compared with placebo. Biological activity, as detected by a statistically significant reduction in thrombin-antithrombin complexes (TATc), was noted in the all rTFPI-treated patients compared with those receiving placebo. There were no major imbalances across all treatment groups with respect to safety. The frequency of adverse events (AEs) and severe adverse events (SAEs) was similar among the treatment groups, with a slight increase in SAEs and SAEs involving bleeding in the 0.05 mg/kg/hr rTFPI group. The overall incidence of AEs involving bleeding was 28% of patients in the all placebo group and 23% of patients in the all rTFPI-treated group; a slight but statistically insignificant increase in incidence of SAEs involving bleeding was observed in the all rTFPI group (9%) as compared with the all placebo group (6%;p = .39). Conclusions Although the trial was not powered to show efficacy, a trend toward reduction in 28-day all-cause mortality was observed in the all rTFPI group compared with all placebo. This study demonstrates that rTFPI doses of 0.025 and 0.05 mg/kg/hr could be safely administered to severe sepsis patients. Additionally, rTFPI demonstrated bioactivity, as shown by reduction in TATc complexes and interleukin-6 levels. These findings warrant further evaluation of rTFPI in an adequately powered, placebo controlled, randomized trial for the treatment of severe sepsis.

The activity of tissue factor pathway inhibitor in experimental models of superantigen-induced shock and polymicrobial intra-abdominal sepsis.

ObjectivesTo study recombinant human tissue factor pathway inhibitor (rhTFPI) in a superantigen-induced shock model and in a cecal ligation and puncture (CLP) model of peritonitis in mice. DesignProspective, randomized, experimental study. SettingAn experimental animal research laboratory. SubjectsEighty BALB/c mice for the superantigen model, and 56 BALB/c mice for the CLP model. InterventionsIn the superantigen-induced shock model, animals received rhTFPI (350 mg/kg) subcutaneously every 12 hrs (n = 30) or saline control (n = 30) for 60 hrs after staphylococcal enterotoxin B (SEB; 10 &mgr;g iv) and a sublethal dose of E. coli O111:B4 lipopolysaccharide (LPS; 75 &mgr;g ip). Control groups received SEB alone (n = 10) and LPS alone (n = 10). In the CLP model, rhTFPI or saline was given every 8 hrs for 48 hrs by using a 21-gauge needle (n = 9) or 23-gauge needle (n = 14) for CLP. A sham surgery control group (n = 10) was also included. Measurements and Main Results There was 0% mortality in the SEB and LPS control groups. The mortality rate was 64% in the saline control group that received both SEB and LPS (19 of 30), whereas the rhTFPI- treated animals had a mortality rate of 20% (6 of 30;p < .01). The rhTFPI-treated group had significantly lower interleukin-6 levels (61.8 ± 41 pg/mL vs. 285 ± 63 pg/mL;p < .05) than the control group but no differences in tumor necrosis factor-&agr; or interferon-&ggr; levels.In the CLP experiment, rhTFPI-treated animals did not have any survival advantage over the control group after the large-bore (21-gauge) needle puncture. The rhTFPI group had significantly improved 7-day mortality rate after CLP with the small-bore needle (23-gauge; 21.4% [rhTFPI] vs. 71.4% [control], p < .01). Plasma LPS, interleukin-6, interferon-&ggr;, and tumor necrosis factor-&agr; levels were unchanged by rhTFPI treatment, but significantly reduced LPS (p = .006) and IFN&ggr; (p = .001) levels were found in the peritoneal fluid. ConclusionsTissue factor pathway inhibitor significantly improves the mortality rate in models of superantigen-induced shock and polymicrobial intra-abdominal infection, supporting its potential use in clinical trials for septic shock.

Tissue factor pathway inhibitor activity in severe sepsis.

ObjectiveTo review the preclinical and clinical evidence that provides the therapeutic rationale for recombinant human tissue factor pathway inhibitor (rTFPI) as a novel treatment for human sepsis. Data SourcesA summary of published English-language literature regarding preclinical studies and limited information published about three phase II clinical studies for the evaluation of rTFPI safety in sepsis patients. Data SummaryTissue factor pathway inhibitor, the physiologic inhibitor of the tissue factor pathway, interrupts activation of coagulation at multiple steps, including tissue factor VIIa activity, Xa activity, prothrombinase complex, and thrombin generation. Recombinant human TFPI exhibits anticoagulant and anti-inflammatory activities in animal models and humans with sepsis. These activities appear to have an important therapeutic role in protecting the microvasculature from injury and preventing multiple organ failure in sepsis. ConclusionsTissue factor pathway inhibitor is a potent inhibitor of clotting in the microvasculature, which is thought to protect organs from injury. Recombinant TFPI improved survival of septic animals in multiple models. Recent phase II results suggest that rTFPI is well tolerated, and they show a trend toward reduction in 28-day all-cause mortality in rTFPI-treated patients; in addition, rTFPI demonstrated significant reduction in thrombin generation. These results suggest that a powered study is indicated to further evaluate rTFPI utility for the adjunctive management of severe sepsis.

A clinical evaluation committee assessment of recombinant human tissue factor pathway inhibitor (tifacogin) in patients with severe community-acquired pneumonia

IntroductionThe purpose of this analysis was to determine the potential efficacy of recombinant human tissue factor pathway inhibitor (tifacogin) in a subpopulation of patients with community-acquired pneumonia (CAP) from a phase III study of severe sepsis.MethodsA retrospective review of patients with suspected pneumonia was conducted by an independent clinical evaluation committee (CEC) blinded to treatment assignment. The CEC reanalyzed data from patients enrolled in an international multicenter clinical trial of sepsis who had a diagnosis of pneumonia as the probable source of sepsis. The primary efficacy measure was all-cause 28-day mortality.ResultsOf 847 patients identified on case report forms with a clinical diagnosis of pneumonia, 780 (92%) were confirmed by the CEC to have pneumonia. Of confirmed pneumonia cases, 496 (63.6%) met the definition for CAP. In the CEC CAP population, the mortality rates of the tifacogin and placebo groups were 70/251 (27.9%) and 80/245 (32.7%), respectively. The strongest signals were seen in patients with CAP not receiving concomitant heparin, having microbiologically confirmed infection, or having the combination of documented infection and no heparin. The reduction in mortality in this narrowly defined subgroup when treated with tifacogin compared with placebo was statistically significant (17/58 [29.3%] with tifacogin and 28/54 [51.9%] with placebo; unadjusted P value of less than 0.02).ConclusionsTifacogin administration did not significantly reduce mortality in any severe CAP patient. Exploratory analyses showed an improved survival in patients who did not receive concomitant heparin with microbiologically confirmed infections. These data support the rationale of an ongoing phase III study exploring the potential benefit of tifacogin in severe CAP.Trial RegistrationClinicalTrials.gov identifier NCT00084071.

Randomized, blinded, placebo-controlled trial of tissue factor pathway inhibitor in porcine septic shock.

ABSTRACT This study tested the hypothesis that tissue factor pathway inhibitor (TFPI) would improve mortality and morbidity evoked by peritonitis-induced bacteremia in pigs. Secondarily, it sought to determine if TFPI treatment would attenuate cardiodynamic abnormalities produced by this septic model. 32 pigs were chronically instrumented with intracardiac transducers to measure left ventricular pressure and diameter, pulmonary and aortic pressures, and cardiac output. At least 5 days after surgery to implant transducers, basal cardiovascular readings and blood samples were obtained. Using a randomized, blinded study design, either purified, reconstituted TFPI (1 mg/kg bolus, 10 mg/kg/min for 48 h), placebo (arginine buffer), or saline was administered to pigs immediately after Escherichia coli 0111.B4 (3.0–11 ± 109 colony-forming U/kg)-laden fibrin clots were implanted intraperitoneally, producing peritonitis and bacteremia. Pigs did not receive antibiotics or supportive therapy. No significant differences in primary or secondary endpoints were noted between the arginine and saline groups, so these data were combined into a control group (N = 20). 5 of 12 TFPI pigs survived (42%), while 5 of 20 control pigs survived (25%); this difference was not significant (p = .714, Fishers exact test). TFPI treatment augmented cardiac output in surviving pigs, but did not affect any other cardiovascular performance variable (heart rate, % diameter shortening, or systemic and pulmonary vascular resistance). In controls, peritonitis induced rapid increase in plasma tumor necrosis factor-± (428 ± 771 to 5,933 ± 559 pg/mL at 2 h) and interleukin-8 (180 ± 153 to 1,393 ± 145 pg/mL at 2 h). TFPI treatment significantly attenuated cytokine responses to sepsis, reducing peak tumor necrosis factor-± to 2,103 ± 813 pg/mL and reducing peak interleukin-8 levels to 534 ± 211 pg/mL at 2 h (p < .05, Tukey test, two-way ANOVA). In conclusion, TFPI treatment attenuated important mediator components of the inflammatory response but did not provide significant survival benefit.

Enhanced Bioavailability of a Poorly Water-Soluble Weakly Basic Compound Using a Combination Approach of Solubilization Agents and Precipitation Inhibitors: A Case Study

Poorly water-soluble weakly basic compounds which are solubilized in gastric fluid are likely to precipitate after the solution empties from the stomach into the small intestine, leading to a low oral bioavailability. In this study, we reported an approach of combining solubilization agents and precipitation inhibitors to produce a supersaturated drug concentration and to prolong such a drug concentration for an extended period of time for an optimal absorption, thereby improving oral bioavailability of poorly water-soluble drugs. A weakly basic compound from Johnson and Johnson Pharmaceutical Research and Development was used as a model compound. A parallel microscreening precipitation method using 96-well plates and a TECAN robot was used to assess the precipitation of the tested compound in the simulated gastric fluid (SGF) and the simulated intestinal fluid (SIF), respectively, for lead solubilizing agents and precipitation inhibitors. The precipitation screening results showed vitamin E TPGS was an effective solubilizing agent and Pluronic F127 was a potent precipitation inhibitor for the tested compound. Interestingly, the combination of Pluronic F127 with vitamin E TPGS resulted in a synergistic effect in prolonging compound concentration upon dilution in SIF. In addition, HPMC E5 and Eudragit L100-55 were found to be effective precipitation inhibitors for the tested compounds in SGF. Furthermore, optimization DOE study results suggested a formulation sweet spot comprising HPMC, Eudragit L 100-55, vitamin E TPGS, and Pluronic F127. The lead formulation maintained the tested compound concentration at 300 μg/mL upon dilution in SIF, and more than 70% of the compound remained solubilized compared with the compound alone at <1 μg/mL of its concentration. Dosing of the solid dosage form predissolved in SGF in dogs resulted in 52% of oral bioavailability compared to 26% for the suspension control, a statistically significant increase (p = 0.002). The enhanced oral bioavailability of the tested compound could be attributed to generation and prolongation of a supersaturated drug concentration in vivo by the solubilizing agents and precipitation inhibitors. The study demonstrates that the combination approach of solubilization agents and precipitation inhibitors provides improved oral bioavailability for a poorly water-soluble weakly basic compound.