Development of Monothiol Human Thioredoxin-1 (ORP100S) as an Inhaled Treatment for Acute Viral Lung Injury

Background and Rationale: Pulmonary insult caused by viral infection is a primary cause of acute lung injury (ALI) and its severe form, acute respiratory distress syndrome (ARDS). Established respiratory viruses including H1N1 and H5N1 influenza, herpes simplex virus (HSV), and adenovirus HAdV-B2 are associated with ALI/ARDS, resulting in ~190,000 U.S. cases annually with mortality ranging from 27% to 47%. The emergence of novel pandemic coronavirus SARS-CoV-2 in late 2019 has caused a further 217 million additional respiratory infections worldwide, many of them severe, with 4.5 million deaths. Despite rapid development of vaccines, highly infectious new variants and limited efficacy of available treatments have only increased the urgency for development of safe and effective therapies for acute and chronic lung injury/disorders. Of particular interest are pathogen-agnostic strategies that may also be effective against future novel viral strains. Human thioredoxin (TRX) is a target-selective thiol-disulfide exchange enzyme that acts homeostatically in the lung to modulate inflammatory cytokine release and abnormal airway mucus viscoelasticity via regulatory interaction with extracellular cell-surface protein disulfides. TRX lowers inflammation in acute lung injury, and published studies show it can prevent viral pneumonia and increase survival in influenza-infected mice. Despite obvious potential as a therapeutic, TRX in its native form exhibits poor pharmacology by injection and has intracellular as well as extracellular activities, creating theoretical potential for undesirable off-target effects. To solve this problem, we have utilized protein design strategies to develop a modified TRX, ORP100S, optimized for extracellular delivery and function with greatly increased half-life and decreased potential for intracellular uptake and off-target activity (U.S. Patent 9,168,290). This molecule was shown to lack test article-related acute toxicity and attenuated neutrophil influx and inflammatory cytokine release levels in rats, and demonstrated anti-inflammatory activity in human lung cell microcosms in vitro. ORP100S was found to be a potent normalizer of human airway mucus and sputum and restored normal mucociliary transport ex vivo on living tracheae with transplanted obstructive sputum from human patients with cystic fibrosis. Our results, along with the published literature on TRX, suggest that ORP100S has excellent potential to be a safe and effective treatment for serious airway diseases, including ALI/ARDS associated with COVID-19 and other viruses. Objective: Our overall objective is to advance ORP100S to human clinical trials for approval. Key components of our development plan include establishing minimum effective dose levels based on an understanding of the pharmacodynamic effect of ORP100S in vitro and in vivo for relevant viral diseases (COVID-19 and influenza), as well as establishing a validated bioanalytical method for the detection and quantification of ORP100S in plasma/serum and lung matrices from humans and non-clinical toxicology species (rat and non-human primate). Proposed Research: In the current proposal, we plan to complete the following specific aims: 1) In vitro pharmacodynamics of ORP100S in 3-D lung organoids that authentically recapitulate disease. 2) In vivo pharmacodynamics of ORP100S in a Syrian golden hamster SARS-CoV-2 post-exposure prophylaxis infection model. 3) In vivo pharmacodynamics of inhaled ORP100S in a mouse influenza model. 4) Develop and validate a hybrid immunocapture-LC-MS/MS bioanalytical method for the quantitation of ORP100S in bronchiolar lavage fluid and serum/plasma matrices. Impact: Near term, the proposed project will enable us to conduct Investigational New Drug (IND)-enabling toxicology studies and build a pharmacology data package to support first in human trials via a U.S. Food and Drug Administration (FDA) IND filing. These are critical development milestones toward clinical evaluation of ORP100S. Subsequent efforts will encompass clinical studies to demonstrate safety and efficacy in order to advance to FDA approval and commercialization. Based on its novel host-directed mechanism, ORP100S is positioned to fill a key treatment gap to minimize the need for hospitalization due to respiratory viral infection by reducing the progression to late-stage severe disease. Relevance: ORP100S is proposed as a novel therapy for viral acute and chronic lung injury/disorders that is suitable for home or field administration. As a host-directed treatment, it will also enhance preparedness for future pandemics caused by yet-unknown pathogens. As of August 25, 2021, there were over 341,000 COVID-19 cases in the U.S. Department of Defense (DOD) (military and civilian) with 419 deaths, and over 315,000 cases identified at Department of Veterans Affairs (VA) facilities (13,693 deaths). In 2019-20, influenza resulted in 405,000 hospitalizations and 22,000 deaths. ORP100S has particular military relevance as it may also treat chronic obstructive airway diseases such as chronic obstructive pulmonary disease (COPD) that have a disproportionately high incidence rate in military personnel and Veterans and may predispose to severe COVID. Less