EVERE SEPSIS, A SYNDROME OF acute infection complicated by organ dysfunction, is caused by a dysregulated systemic inflammatory response. Sepsis can progress to systemic hypotension (septic shock), 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, Ϫ1.1; 95% CI, Ϫ5.3 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.

Summary There is pressing need to develop alternatives to annual influenza vaccines and antiviral agents licensed for mitigating influenza infection. Previous studies reported that acute lung injury (ALI) caused by chemical or microbial insults is secondary to generation of host-derived, oxidized phospholipid that potently stimulates Toll-like Receptor 4 (TLR4)-dependent inflammation1. Subsequently, we reported that TLR4−/− mice are highly refractory to influenza-induced lethality2, and hypothesized that therapeutic antagonism of TLR4 signaling would protect against influenza-induced ALI. Herein, we report that therapeutic administration of Eritoran (E5564), a potent, well-tolerated, synthetic TLR4 antagonist3,4, blocks influenza-induced lethality in mice, as well as lung pathology, clinical symptoms, cytokine and oxidized phospholipid expression, and decreases viral titers. CD14 and TLR2 are also required for Eritoran-mediated protection, and CD14 directly binds Eritoran and inhibits ligand binding to MD2. Thus, Eritoran blockade of TLR signaling represents a novel therapeutic approach for inflammation associated with influenza, and possibly other, infections.

␣-D-Glucopyranose,3-O-decyl-2-deoxy-6-O-[2-deoxy-3-O-[(3R)-3-methoxydecyl]-6-O-methyl-2-[[(11Z)-1-oxo-11-octadecenyl]amino]-4-O-phosphono-␤-D-glucopyranosyl]-2- [(1,3-dioxotetradecyl)amino]-1-(dihydrogen phosphate), tetrasodium salt (E5564) is a second-generation synthetic lipodisaccharide designed to antagonize the toxic effects of endotoxin, a major immunostimulatory component of the outer cell membrane of Gram negative bacteria. In vitro, E5564 dose dependently (nanomolar concentrations) inhibited lipopolysaccharide (LPS)-mediated activation of primary cultures of human myeloid cells and mouse tissue culture macrophage cell lines as well as human or animal whole blood as measured by production of tumor necrosis factor-␣ and other cytokines. E5564 also blocked the ability of Gram negative bacteria to stimulate human cytokine production in whole blood. In vivo, E5564 blocked induction of LPS-induced cytokines and LPS or bacterial-induced lethality in primed mice. E5564 was devoid of agonistic activity when tested both in vitro and in vivo and has no antagonistic activity against Gram positive-mediated cellular activation at concentrations up to 1 M. E5564 blocked LPSmediated activation of nuclear factor-B in toll-like receptor 4/MD-2-transfected cells. In a mouse macrophage cell line, activity of E5564 was independent of serum, suggesting that E5564 exerts its activity through the cell surface receptor(s) for LPS, without the need for serum LPS transfer proteins. Similar, another lipid A-like antagonist, E5564 associates with plasma lipoproteins, causing low concentrations of E5564 to be quantitatively inactivated in a dose-and time-dependent manner. However, compared with E5531, E5564 is a more potent inhibitor of cytokine generation, and higher doses retain activity for durations likely sufficient to permit clinical application. These results indicate that E5564 is a potent antagonist of LPS and lacks agonistic activity in human and animal model systems, making it a potentially effective therapeutic agent for treatment of disease states caused by endotoxin.

Acute graft-versus-host disease (GVHD) and leukemic relapse remain the two major obstacles to successful outcomes after allogeneic bone marrow transplantation (BMT). Recent studies have demonstrated that the loss of gastrointestinal tract integrity, and specifically the translocation of LPS into the systemic circulation, is critical to the induction of cytokine dysregulation that contributes to GVHD. Using a mouse BMT model, we studied the effects of direct LPS antagonism on GVHD severity and graft-versus-leukemia (GVL) activity. Administration of B975, a synthetic lipid-A analogue from day 0 to day +6, reduced serum TNF-α levels, decreased intestinal histopathology, and resulted in significantly improved survival and a reduction in clinical GVHD, compared with control-treated animals. Importantly, B975 had no effect on donor T cell responses to host antigens in vivo or in vitro. When mice received lethal doses of P815 tumor cells at the time of BMT, administration of B975 did not impair GVL activity and resulted in significantly improved leukemia-free survival. These findings reveal a critical role for LPS in the early inflammatory events contributing to GVHD and suggest that a new class of pharmacologic agents, LPS antagonists, may help to prevent GVHD while preserving T cell responses to host antigens and GVL activity.