TREM-1 therapy for the treatment of empyema

Project Summary/Abstract The incidence of empyema is increasing and associated with a mortality rate of 20% in patients older than 65 years. About 30% of patients with advanced empyema have contraindications to surgery, showing an urgent need for novel approaches. The long-term goal of this project is to develop first-in-class TREM-1 therapy for empyema to be used standalone or in combination with single chain tissue plasminogen activator (sctPA, or alteplase) to decrease fibrinolysin dose, minimizing risk of hemorrhagic complications. Parapneumonic effusion and empyema are associated with amplified, acute inflammatory response largely mediated by activated macrophages and neutrophils. TREM-1 is overexpressed on these cells upon inflammation and amplifies inflammatory response. TREM-1 mediates cytokine release and is involved in acute and chronic inflammatory disorders, which implicates TREM-1 as a promising target in inflammation. Targeting TREM-1 in rodent empyema and pneumonia models resulted in a decrease in the inflammation and pleural injury and an increase in the survival. However, current TREM-1 blockers all attempt to block binding of TREM-1 to its unknown ligand(s) and have a risk of failure in the clinic. One of such blockers, LR12 peptide developed by Inotrem (France), recently failed in Phase IIb sepsis trial. To minimize risk of failure in the clinic, we developed a ligand-independent TREM-1 inhibitory peptide sequence GF9 that can be used in a form of free peptide GF9 or as a part of trifunctional peptide GA31 formulated into macrophage-specific lipopeptide complexes (LPC) to improve its half-life and targeting. The hypothesis of this Phase I project is that ligand-independent TREM-1 therapy can be developed as an effective treatment for empyema to suppress inflammation and reduce mortality and morbidity. Earlier, we showed that GF9 and GA31-LPC inhibit inflammatory cytokine release, protect against septic shock and reverse lung fibrosis in mice. Phase I aims to test if these agents attenuate pleural and systemic inflammatory responses in a Streptococcus pneumoniae-induced rabbit model of acute empyema that recapitulates human disease. Considering pros and cons of GF9 and GA31-LPC, we suggest to test both. Specific aims of this project are to: 1) generate and characterize in vitro GMP-friendly GF9 and GA31- LPC injectables, and 2) test GF9 and GA31-LPC comparatively in a rabbit model of acute empyema. We will synthesize and characterize GMP-friendly GF9 and GA31-LPC for their composition, size, stability, and inhibitory effect on cytokine release by LPS-stimulated U937 macrophages. We will then test two doses of GF9 and GA31-LPC in rabbits with acute empyema. We will monitor development of empyema and analyze pleural inflammation and injury. Comprehensive histology/IHC studies will be performed. It is anticipated that this Phase I study will identify a novel, first-in-class, well-tolerable agent as a powerful platform for development of safe and effective therapy capable of treating empyema.