Concurrent targeting of inflammation and the inhibition of the fibrinolytic system to increase the efficacy of empyema treatment - Abstract: The incidence and mortality of empyema or pleural sepsis has steadily risen over the past several decades. While, after antibiotics, surgery is widely accepted as the first choice to treat empyema in adults, up to 30% of patients are poor candidates for both surgery and conventional high dose intrapleural fibrinolytic therapy (IPFT). Substituting non-surgical drainage of pleural fluid with a low-dose Alteplase (ALT)-based intervention could positively affect the survival of patients with advanced-stage empyema. Our preclinical studies in three rabbit models of pleural injury have demonstrated that Docking Site Peptide (DSP) increases the efficacy of Alteplase (ALT) up to 8-fold by affecting Plasminogen Activator Inhibitor 1 (PAI-1). Next, we determined that a decrease in intrapleural inflammation coincides with successful treatment with ALT/DSP in a model of advanced- stage empyema (effective bolus dose of ALT is unknown; >13.5 mg). Thus, targeting both pleural fibrosis and inflammation may result in a further increase in the efficacy of ALT in our preclinical model, which closely recapitulates empyema in humans. Increased levels of the Triggering Receptor Expressed on Myeloid Cells 1 (TREM-1) and proinflammatory biomarkers in pleural fluids of patients with empyema and rabbit models of empyema indicate TREM-1-mediated activation of inflammation. A TREM-1 peptide inhibitor, GF9, will be tested with ALT/DSP (ALT/DSP/GF9) in rabbit models of acute and advanced-stage empyema in order to further increase the efficacy of ALT. This milestone driven MPI proposal is focused on preclinical testing and optimization of a novel therapeutic strategy (Two-Target Fibrinolytic Therapy; T2FT), concurrently targeting two distinct mechanisms that contribute to disease severity and therapeutic outcomes of several thrombotic and fibrotic pathologies (R61), followed by the development, formulation and testing of a novel T2FT Product (DSP/GF9) suitable for rapid translation to clinical trials (R33). Our hypothesis is that simultaneous targeting of TREM-1 and PAI-1 mechanisms with short peptides GF9 and DSP is a clinically tractable strategy to increase the efficacy of ALT in the treatment of empyema. Our objective is to develop a T2FT Product (DSP/GF9) that, in combination with low dose of ALT, is suitable for treatment of high-risk patients with advanced-stage empyema. T2FT offers a novel pharmacological option for patients who are recommended for surgery but either decline or are at too high a risk for surgery or high ALT dose IPFT. Our hypothesis will be tested and objective achieved in three specific Aims: (i) Development and preclinical validation of a low dose T2FT in a rabbit model of acute, early- stage empyema (R61); (ii) Optimization and preclinical validation of low dose T2FT for advanced-stage empyema in a rabbit model (R61); (iii) GMP-friendly pilot production, stability, formulation, toxicity, and efficacy studies of low dose ALT single injection T2FT treatment for translation to clinical application (R33). This is a genuine University/Industry collaboration that focuses on the development and commercialization of a novel treatment. UTHSCT (Contact PI: Dr. Komissarov) contributes a validated rabbit model of empyema, ALT/DSP methodology, and matching funds. SignaBlok (PI: Dr. Sigalov) contributes well-tolerable formulations of GF9, a novel mechanism-based TREM-1 inhibitory peptide that has been validated preclinically in multiple inflammation- associated pathologies, and over 13 years of industrial experience to serve as a business accelerator and steer the project towards the market. The anticipated product, a GMP-friendly low-dose T2FT for empyema will be manufactured in a pilot. If successful, this project could elucidate a Catalyze-guided bench-to-bedside pathway towards industry.
