Effect of eritoran, an antagonist of MD2-TLR4, on mortality in patients with severe sepsis: the ACCESS randomized trial.

IMPORTANCE: Eritoran is a synthetic lipid A antagonist that blocks lipopolysaccharide (LPS) from binding at the cell surface MD2-TLR4 receptor. LPS is a major component of the outer membrane of gram-negative bacteria and is a potent activator of the acute inflammatory response. OBJECTIVE: To determine if eritoran, a TLR4 antagonist, would significantly reduce sepsis-induced mortality. DESIGN, SETTING, AND PARTICIPANTS: We performed a randomized, double-blind, placebo-controlled, multinational phase 3 trial in 197 intensive care units. Patients were enrolled from June 2006 to September 2010 and final follow-up was completed in September 2011. INTERVENTIONS: Patients with severe sepsis (n = 1961) were randomized and treated within 12 hours of onset of first organ dysfunction in a 2:1 ratio with a 6-day course of either eritoran tetrasodium (105 mg total) or placebo, with n = 1304 and n = 657 patients, respectively. MAIN OUTCOME MEASURES: The primary end point was 28-day all-cause mortality. The secondary end points were all-cause mortality at 3, 6, and 12 months after beginning treatment. RESULTS: Baseline characteristics of the 2 study groups were similar. In the modified intent-to-treat analysis (randomized patients who received at least 1 dose) there was no significant difference in the primary end point of 28-day all-cause mortality with 28.1% (366/1304) in the eritoran group vs 26.9% (177/657) in the placebo group (P = .59; hazard ratio, 1.05; 95% CI, 0.88-1.26; difference in mortality rate, -1.1; 95% CI, -5.3 to 3.1) or in the key secondary end point of 1-year all-cause mortality with 44.1% (290/657) in the eritoran group vs 43.3% (565/1304) in the placebo group, Kaplan-Meier analysis of time to death by 1 year, P = .79 (hazard ratio, 0.98; 0.85-1.13). No significant differences were observed in any of the prespecified subgroups. Adverse events, including secondary infection rates, did not differ between study groups. CONCLUSIONS AND RELEVANCE: Among patients with severe sepsis, the use of eritoran, compared with placebo, did not result in reduced 28-day mortality. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00334828.

Phase 2 trial of eritoran tetrasodium (E5564), a toll-like receptor 4 antagonist, in patients with severe sepsis.

OBJECTIVES: Endotoxin is a potent stimulus of proinflammatory response and systemic coagulation in patients with severe sepsis. Endotoxin is a component of Gram-negative bacteria that triggers an innate immune response through Toll-like receptor 4 signaling pathways in myeloid cells. We evaluated safety and tolerability of two dose regimens of eritoran tetrasodium (E5564), a synthetic Toll-like receptor 4 antagonist, and explored whether it decreases 28-day mortality rate in subjects with severe sepsis. DESIGN: Prospective, randomized, double-blind, placebo-controlled, multicenter, ascending-dose phase II trial. SETTING: Adult intensive care units in the United States and Canada. PATIENTS: Three hundred adults within 12 hrs of recognition of severe sepsis, with Acute Physiology and Chronic Health Evaluation (APACHE) II-predicted risk of mortality between 20% and 80%. INTERVENTIONS: Intravenous eritoran tetrasodium (total dose of either 45 mg or 105 mg) or placebo administered every 12 hrs for 6 days. MEASUREMENTS AND MAIN RESULTS: Prevalence of adverse events was similar among subjects treated with 45 mg or 105 mg of eritoran tetrasodium or with placebo. For modified intent-to-treat subjects, 28-day all-cause mortality rates were 26.6% (eritoran tetrasodium 105 mg), 32.0% (eritoran tetrasodium 45 mg), and 33.3% in the placebo group. Mortality rate in the eritoran tetrasodium 105-mg group was not significantly different from placebo (p = .335). In prespecified subgroups, subjects at highest risk of mortality by APACHE II score quartile had a trend toward lower mortality rate in the eritoran tetrasodium 105-mg group (33.3% vs. 56.3% placebo group, p = .105). A trend toward a higher mortality rate was observed in subjects in the lowest APACHE II score quartile for the eritoran 105-mg group (12.0% vs. 0.0% placebo group, p = .083). CONCLUSIONS: Eritoran tetrasodium treatment appears well tolerated. The observed trend toward a lower mortality rate at the 105-mg dose, in subjects with severe sepsis and high predicted risk of mortality, should be further investigated.

TLR4 antagonists for endotoxemia and beyond.

Toll-like receptor 4 (TLR4) controls the major responding signaling system that detects the presence of Gram-negative infectious pathogens, by responding to endotoxin from their outer membrane. Normally, TLR-bearing cells signal the immune system to mount a pro-inflammatory, antibacterial response and resolve infection. However, TLR4 can also respond to a variety of 'endogenous' ligands, such as fibronectin and heat shock proteins. Overstimulation or continued stimulation of TLR4 by any ligand can result in a systemic inflammatory response, progressing to hypotension, shock, organ failure and even death. This review discusses current, preclinical and clinical research regarding eritoran (E-5564), an analog of the non-toxic lipid A from Rhodobacter sphaeroides, as well as other antagonists of TLR4 in a variety of diseases.

Antagonism of in vivo and ex vivo response to endotoxin by E5564, a synthetic lipid A analogue.

E5564, a synthetic lipid A analogue, is a selective, highly active antagonist of endotoxin-mediated activation of immune cells. Preclinical research has indicated that E5564 can block endotoxin-mediated induction of cytokines and endotoxin or Gram-negative bacterial-induced death in animal models. Recent phase I clinical trials have focused on the ability of E5564 to block responsiveness to endotoxin. This was done in two ways: in vivo challenge of human volunteers with 4 ng/kg endotoxin, and by use of an ex vivo assay which utilizes blood drawn from volunteers administered E5564 and challenged with endotoxin at concentrations that ranged from 50 pg/ml to 10 ng/ml. In vivo, > or = 100 microg of E5564 completely blocked signs, symptoms and cytokines induced by concomitantly-administered endotoxin. In contrast, subjects receiving a 50 microg dose of E5564 demonstrated a graded response; cytokines were inhibited > or = 95%, but many signs and symptoms of endotoxemia were still evident. E5564 demonstrated a long pharmacokinetic half-life (> 30 h); however, ex vivo analysis indicated that while single doses of 350 microg induced a nearly complete block of the effects of 1 ng/ml endotoxin immediately upon E5564 administration, antagonistic activity declined rapidly (t(1/2) < 1 h). Similar results were obtained in vivo using a delayed endotoxin challenge. These results have driven us to examine antagonistic activity of E5564 in vivo and ex vivo after administration by continuous infusion or twice-daily dosing. Results from these multiple-dose studies indicate that under these conditions of administration, plasma levels of E5564 can be predictive of long-term pharmacodynamic activity.

Experimental human endotoxemia is associated with depression of load-independent contractility indices: prevention by the lipid a analogue E5531.

OBJECTIVE: To evaluate the efficacy of a novel lipopolysaccharide (LPS) antagonist, E5531, in blocking LPS-induced cardiac responses including myocardial depression (as assessed by relatively load-independent echocardiographic indices of contractility) in a human model of experimental endotoxemia. DESIGN: Randomized, prospective, placebo-controlled, double-blind trial. SETTING: ICU procedure room. PARTICIPANTS: Thirty-two healthy, male volunteers. INTERVENTIONS: Administration of LPS (4 ng/kg) and either a placebo or one of four sequential doses of E5531 (100 microg, 250 microg, 500 microg, or 1,000 microg) followed by volumetric echocardiography before and during 4-L saline solution infusion (3 L over 3 h, followed by 1 L over 2 h). RESULTS: In addition to the generation of a hyperdynamic circulation throughout the study period, administration of LPS resulted in a biphasic contractility response. Ejection fraction (EF), rate-corrected mean velocity of circumferential fiber shortening (Vcfc), peak systolic BP (SBP)/end-systolic volume index (ESVI) ratio, and end-systolic pressure (Pes)/ESVI ratio increased at the 3-h post-LPS assessment, compared to a control group of subjects receiving only similar amounts of saline solution (minimum p < 0.001). End-systolic myocardial wall stress (sigmaes)/ESVI ratio, one of the most load independent of the contractility indices, was unchanged. At 5 h after endotoxin, EF, Vcfc, SBP/ESVI, Pes/ESVI, and sigmaes/ESVI were all decreased (minimum p < 0.01), indicating myocardial depression. When present, early (3 h after LPS), apparent enhancement of myocardial contractility and later (5 h after LPS) myocardial depression were substantially blunted by administration of E5531 (minimum p < 0.025), typically in a concentration-dependent manner. CONCLUSIONS: Endotoxin generates significant myocardial depression when measured using highly load-independent indices of cardiac contractility. E5531 is a potent inhibitor of the early hyperdynamic cardiovascular and later myocardial depression response seen in experimental human endotoxemia.

Safety, pharmacokinetics, and pharmacodynamics of E5564, a lipid A antagonist, during an ascending single-dose clinical study.

E5564, a structural analog of the lipid A portion of lipopolysaccharide (LPS), is a potent antagonist of the biochemical and physiologic effects of LPS in several in vitro and in vivo models and is currently under clinical development as a possible therapeutic for the treatment of sepsis and septic shock. The objectives of this study were to (1) assess the safety and tolerability of E5564 following a 30-minute intravenous (i.v.) infusion, (2) evaluate the pharmacokinetic profile of E5564, and (3) measure the ability of E5564 to block LPS stimulation ex vivo in blood taken from subjects up to 8 hours after ending the infusion. Healthy male volunteers (n = 7/dose group) were randomly assigned to each of four dose levels (350, 1000, 2000, or 3500 micrograms). Within each dose group, 5 subjects received drug and 2 received placebo. E5564 or matching placebo was administered by a 30-minute infusion, and blood samples were collected at predetermined time points. All doses of E5564 were demonstrated to be safe and well tolerated. E5564 plasma concentrations were determined using a validated LC/MS/MS method. The Cmax and AUC of E5564 increased in a dose-proportional manner. E5564 pharma-cokinetics were characterized by a slow clearance (0.67-0.95 mL/h/kg), a small volume of distribution (41-54 mL/kg), and a relatively long elimination half-life (42-51 h). As measured in the ex vivo assay, E5564 inhibited LPS-induced tumor necrosis factor-alpha (TNF-alpha) in a dose-dependent manner, and at the higher doses (2 and 3.5 mg), antagonistic activity was measurable up to 8 hours postinfusion. E5564 lacked LPS-like agonist activity at doses up to 3.5 mg. Taken together, we believe that E5564 is a safe, potent antagonist of LPS in blood and will likely benefit patients in the treatment of LPS-related diseases.

Deactivation of the lipopolysaccharide antagonist eritoran (E5564) by high-density lipoprotein-associated apolipoproteins.

Lipid A, the active moiety of LPS, exerts its effects through interaction with TLR4, triggering a signalling cascade that results in the release of pro-inflammatory cytokines. Eritoran is a lipid A analogue that competes with LPS for binding to TLR4; however, after intravenous administration, it undergoes a time-dependent deactivation as a consequence of binding to high-density lipoproteins (HDLs). The site of eritoran association with HDL remains unknown. Therefore the aim of this study was to determine if HDL-associated apolipoproteins A1, A2, serum amyloid A (SAA) and C1, inhibit the ability of eritoran to block LPS-induced TNF-α release from whole blood. Eritoran activity after LPS stimulation in human whole blood was assessed in the presence of reconstituted HDL (rHDL) containing different apos. In rHDL, the major apolipoproteins in both the healthy and septic state, A1 and SAA, caused a significant reduction in eritoran antagonistic activity and had a greater effect than minor apolipoproteins A2 and C1. Apolipoproteins associated with HDL are likely to facilitate eritoran deactivation. Apolipoproteins A1 and SAA should be of particular focus as they are the major apos found on HDL in both the healthy and septic state. Further evaluation of the physical association between apolipoproteins and eritoran should be explored.

Safety, pharmacokinetics and pharmacodynamics of four-hour intravenous infusions of eritoran in healthy Japanese and Caucasian men.

Eritoran, a synthetic analogue of lipid A, has been shown to bind to TLR4/MD-2 complex and thereby block the interaction of endotoxins with TLR4. We report here the results of a study conducted to assess the single-dose safety and tolerability, as well as the pharmacokinetics and pharmacodynamics, of eritoran infusion in Japanese and Caucasian healthy adult men. Sixty-four men (aged 20-45 years; body mass index 18-30 kg/m(2)) were randomized into four groups: 4-mg total dose (six Japanese and six Caucasian men); 12-mg total dose (12 Japanese and 12 Caucasian men); 28-mg total dose (six Japanese and six Caucasian men); and placebo (eight Japanese and eight Caucasian men). Eritoran in single doses up to 28 mg over 4 h was well tolerated, with no apparent ethnic differences noted. Plasma concentrations were slightly higher in Japanese versus Caucasian men; these differences were not significant after adjustment for differences in body mass (clearance: approximately 1.2 ml/h/kg; volume of distribution at steady state: approximately 0.07 l/kg). The ex vivo endotoxin inhibitory activity of eritoran was similar in Japanese and Caucasian men. The data do not indicate any need for clinical dose adjustment for possible ethnic-based differences in drug distribution or metabolism.

Influence of severity of illness on the effects of eritoran tetrasodium (E5564) and on other therapies for severe sepsis.

Disease severity varies widely in patients with severe sepsis. Eritoran tetrasodium (E5564), a TLR4 antagonist, blocks the binding of endotoxin and is being evaluated as a novel therapy for severe sepsis. This analysis aimed to assess the efficacy of eritoran based on severity of illness and similar effects in other recent sepsis trials. Prospective covariates from a randomized, double-blind, placebo-controlled, phase 2 trial were analyzed for treatment interaction measured by 28-day mortality. Five statistical interaction methodologies were used. The modified intent-to-treat population (n = 292), all-cause 28-day mortality was as follows: placebo, 33.3% (32/96); eritoran 45 mg/105 mg, 29.6% (58/196). Logistic regression analysis identified Acute Physiology and Chronic Health Evaluation II scores, predicted-risk-of-mortality scores, IL-6, age, sex, race, and eritoran use as associated with survival. Significant treatment interactions were observed (eritoran vs. placebo) for baseline covariates: Acute Physiology and Chronic Health Evaluation II (P = 0.035), predicted-risk-of-mortality scores (P = 0.008), number of organ failures (P = 0.079), international normalized ratio (P = 0.05), and acute physiology score (P = 0.039). I analysis showed that 38% of the total eritoran treatment variance was explained by the severity-of-illness heterogeneity rather than by chance. No interactions observed with other variables. Consistent with the finding in this eritoran trial, other sepsis trials (IL-1 receptor antagonist, TNFsr-p55, antithrombin, drotrecogin alfa-activated) also demonstrated significant treatment by severity interaction. Potential survival benefits of eritoran in severe sepsis patients were associated with high severity of illness. These findings were used to design a phase 3 trial. Similar treatment by severity-of-illness interaction was found in most recent sepsis trials.

Continuous pharmacodynamic activity of eritoran tetrasodium, a TLR4 antagonist, during intermittent intravenous infusion into normal volunteers.

BACKGROUND: Eritoran tetrasodium (E5564), a structural analogue of the lipid A portion of endotoxin (lipopolysaccharide or LPS), is an antagonist of LPS and other Toll-like receptor 4 (TLR4) ligands. Eritoran tetrasodium quantitatively blocks LPS response in vivo in animal and human endotoxemia models and demonstrates a long pharmacokinetic half-life, but a short pharmacodynamic half-life. The objective of this study was to assess the safety, and pharmacokinetic and pharmacodynamic profile of E5564 infused twice-daily at three target steady-state plasma levels of approximately 1, 3 and 10 microg/ml in healthy volunteers. RESULTS: Loading and maintenance doses of up to 77 mg over 3 days in females and 105 mg over 6 days in males were safe and well-tolerated except for self-limiting phlebitis at the drug infusion site. Plasma levels reached steady state by 24 h. The C(max), C(min), and C(88), AUC(0 -infinity) were dose proportional and gender independent. Pharmacodynamic activity measured by an ex vivo LPS challenge assay, demonstrated dose-dependence for both E5564 and LPS and plasma levels of approximately 3 microg/ml E5564 or greater blocked up to 1 ng/ml LPS. CONCLUSIONS: Every 12-h dosing of E5564 can replace continuous infusion, while maintaining uninterrupted blocking of high-dose LPS.

Influence of plasma cholesterol and triglyceride concentrations and eritoran (E5564) micelle size on its plasma pharmacokinetics and ex vivo activity following single intravenous bolus dose into healthy female rabbits.

PURPOSE: Eritoran (E5564) is a glycophospholipid that acts as a toll-like receptor 4 (TLR4) antagonist that is being tested as a treatment for severe sepsis and septic shock. In the blood, eritoran binds to plasma lipoproteins altering its pharmacokinetic and pharmacodynamic (PD) effects in vivo. The purpose of this study was to determine the influence of changes in plasma cholesterol and triglyceride concentrations on the plasma pharmacokinetics and ex vivo activity of eritoran following single intravenous bolus dosing of eritoran to healthy female rabbits fed either a regular chow diet or a cholesterol-enriched diet. This was done with eritoran administered as stable micelle formulations of mean hydrodynamic diameters of 8 or 27 nm). METHODS: Female New Zealand White rabbits were fed a standard diet for 7 days and then randomly assigned either a regular chow diet [regular-diet (n = 9)] or a cholesterol-enriched diet [cholesterol-diet (n = 12)] for an additional 7 days. Following feeding of these diets a single intravenous bolus dose of eritoran (0.5 mg/kg) formulated into either "small micelles" (8 nm in diameter) or "large micelles" (27 nm in diameter) was administered to regular-fed and cholesterol-fed rabbits. Serial blood samples were obtained prior to eritoran administration and at the following times post injection: 0.083 (5 min), 1, 2, 4, 8, 10, 24, 48 and 72 h. Plasma was analyzed for eritoran concentrations using LC/MS/MS. Total plasma cholesterol (TC) and triglyceride (TG) levels were quantified using enzymatic kits. Plasma eritoran pharmacokinetic (PK) parameters were estimated by non-compartmental analysis using the WinNonlin nonlinear estimation program. To analyze PD activity, whole blood obtained at 0.083 (5 min), 2, 24, 48 and 72 h following eritoran administration was assessed for ex vivo activity by measuring the ability of 1 and 10 ng/ml LPS to elicit TNF-alpha release. RESULTS: Total plasma cholesterol and triglyceride levels were significantly higher in cholesterol-fed rabbits compared to the rabbits fed a regular chow diet. Diet had no effect on the estimated plasma PK parameters. However, PD activity of both small and large micelle eritoran as measured by an ex vivo challenge dose of 1 ng/ml LPS was reduced in blood of cholesterol-fed rabbits compared to normal-fed rabbits. Comparison of PK parameters for small and large micelles indicated that small micelles had increased AUC(0-72 h), decreased plasma clearance and increased initial concentration (measured at 5 min post administration) compared to the large micelle formulation. Consistent with this observation, eritoran formulated into small micelles had significantly greater ex vivo activity than large micelles and was independent of TC and TG concentrations. CONCLUSIONS: These findings suggest that plasma pharmacokinetics and activity of eritoran maybe influenced by eritoran micelle size and plasma TC and TG concentrations.

Safety, pharmacokinetics, pharmacodynamics, and plasma lipoprotein distribution of eritoran (E5564) during continuous intravenous infusion into healthy volunteers.

Eritoran, a structural analogue of the lipid A portion of lipopolysaccharide (LPS), is an antagonist of LPS in animal and human endotoxemia models. Previous studies have shown that low doses (350 to 3,500 microg) of eritoran have demonstrated a long pharmacokinetic half-life but a short pharmacodynamic half-life. The present study describes the safety, pharmacokinetics and pharmacodynamics, and lipid distribution profile of eritoran during and after a 72-h intravenous infusion of 500, 2,000, or 3,500 microg/h into healthy volunteers. Except for the occurrence of phlebitis, eritoran administration over 72 h was safe and well tolerated. Eritoran demonstrated a slow plasma clearance (0.679 to 0.930 ml/h/kg of body weight), a small volume of distribution (45.6 to 49.8 ml/kg), and a relatively long half-life (50.4 to 62.7 h). In plasma, the majority (approximately 55%) of eritoran was bound to high-density lipoproteins. During infusion and for up to 72 h thereafter, ex vivo response of blood to 1- or 10-ng/ml LPS was inhibited by > or =85%, even when the lowest dose of eritoran (500 microg/h) was infused. Inhibition of response was dependent on eritoran dose and the concentration of LPS used as an agonist. Finally, in vitro analysis with purified lipoprotein and protein fractions from plasma obtained from healthy volunteers indicated that eritoran is inactivated by high-density but not low-density lipoproteins, very-low-density lipoproteins, or albumin. From these results, we conclude that up to 252 mg of eritoran can be safely infused into normal volunteers over 72 h and even though it associates extensively with high-density lipoproteins, antagonistic activity is maintained, even after infusion ceases.

Association of the endotoxin antagonist E5564 with high-density lipoproteins in vitro: dependence on low-density and triglyceride-rich lipoprotein concentrations.

The objective of this study was to determine the distribution profile of the novel endotoxin antagonist E5564 in plasma obtained from fasted human subjects with various lipid concentrations. Radiolabeled E5564 at 1 microM was incubated in fasted plasma from seven human subjects with various total cholesterol (TC) and triglyceride (TG) concentrations for 0.5 to 6 h at 37 degrees C. Following these incubations, plasma samples were separated into their lipoprotein and lipoprotein-deficient fractions by ultracentrifugation and were assayed for E5564 radioactivity. TC, TG, and protein concentrations in each fraction were determined by enzymatic assays. Lipoprotein surface charge within control and phosphatidylinositol-treated plasma and E5564's influence on cholesteryl ester transfer protein (CETP) transfer activity were also determined. We observed that the majority of E5564 was recovered in the high-density lipoprotein (HDL) fraction. We further observed that incubation in plasma with increased levels of TG-rich lipoprotein (TRL) lipid (TC and TG) concentrations resulted in a significant increase in the percentage of E5564 recovered in the TRL fraction. In further experiments, E5564 was preincubated in human TRL. Then, these mixtures were incubated in hypolipidemic human plasma for 0.5 and 6 h at 37 degrees C. Preincubation of E5564 in purified TRL prior to incubation in human plasma resulted in a significant decrease in the percentage of drug recovered in the HDL fraction and an increase in the percentage of drug recovered in the TRL and low-density lipoprotein fractions. These findings suggest that the majority of the drug binds to HDLs. Preincubation of E5564 in TRL prior to incubation in normolipidemic plasma significantly decreased the percentage of drug recovered in the HDL fraction. Modifications to the lipoprotein negative charge did not alter the E5564 concentration in the HDL fraction. In addition, E5564 does not influence CETP-mediated transfer activity. Information from these studies could be used to help identify the possible components of lipoproteins which influence the interaction of E5564 with specific lipoprotein particles.

Blocking of responses to endotoxin by E5564 in healthy volunteers with experimental endotoxemia.

E5564 is a second-generation synthetic analogue of the lipid A component of endotoxin (lipopolysaccharide [LPS]). The ability of E5564 to block the toxic activity of LPS was assessed in a double-blind, placebo-controlled study. A bolus infusion of endotoxin (4 ng/kg) was administered to healthy subjects to induce a mild transient syndrome similar to clinical sepsis. Single E5564 doses of 50-250 microg ameliorated or blocked all of the effects of LPS in a dose-dependent manner. All E5564 dose groups had statistically significant reductions in elevated temperature, heart rate, C-reactive protein levels, white blood cell count, and cytokine levels (tumor necrosis factor-alpha and interleukin-6), compared with placebo (P<.01). In doses of > or = 100 microg, E5564 acted as an LPS antagonist and completely eliminated these signs. E5564 also blocked or ameliorated LPS-induced fever, chills, headache, myalgia, and tachycardia (P<.01). These results demonstrate that E5564 blocks the effects of LPS in a human model of clinical sepsis and indicate its potential in the treatment and/or prevention of clinical sepsis.

Extended in vivo pharmacodynamic activity of E5564 in normal volunteers with experimental endotoxemia [corrected].

E5564 (alpha-D-glucopyranose) is a synthetic antagonist of bacterial endotoxin that has been shown to completely block human endotoxin response. Low doses of E5564 (0.35-3.5 mg) have a long pharmacokinetic half-life, but a surprisingly short ex vivo and in vivo pharmacodynamic half-life (generally less than several hours). To determine whether extended antagonistic activity can be achieved in vivo, this study assesses the pharmacodynamic activity of 4- and 72-h infusions of E5564 into normal volunteers. Administration of 3.5 mg of E5564/h x 72 h completely blocked effects of endotoxin challenge at the end of dosing (72 h), and at 48 and 72 h postdosing. Similarly, a 4-h infusion of E5564, 3 mg/h completely blocked endotoxin administered 8 h postdosing. A lower dose of E5564, 0.5 mg/h x 4 h, ameliorated but did not block most effects of endotoxin 8 h postdosing (p <0.05). Finally, the effect of varying plasma lipoprotein content on E5564 activity was studied in subjects having high or low cholesterol levels (>180 or <140 mg/dl) after 72-h infusion of 252 mg of E5564. No differences were observed. These results demonstrate that E5564 blocks the effects of endotoxin in a human model of clinical sepsis and indicate its potential in the treatment and/or prevention of clinical sepsis.