Elusys Therapeutics, Inc. (Elusys), a biopharmaceutical company developing antibody therapies to treat infectious disease, presented data demonstrating that obiltoxaximab (ETI-204) demonstrated a statistically significant survival benefit across a range of disease severity in animal model studies assessing treatment of inhalational anthrax, as well as effectiveness in post-exposure prophylaxis. Obiltoxaximab is the company's investigational monoclonal antibody (mAb) anthrax antitoxin for the treatment and prevention of inhalational anthrax used in a bioterror attack. Study results were highlighted in poster presentations at the ASM Biodefense and Emerging Diseases Research meeting being held this week in Washington, DC. Obiltoxaximab is in late stage development, and is a candidate for future acquisition into the Strategic National Stockpile, the U.S. government's repository of critical medical supplies for biowarfare preparedness.
In the first presentation, results of four studies conducted in a monkey treatment model of inhalational anthrax were discussed; survival to 28 days was the primary endpoint. There was significant survival for the majority of obiltoxaximab treatment groups (5/8) over placebo groups (p<0.025). Statistically significant obiltoxaximab survival benefit versus placebo were demonstrated across a range of disease severity. Survival outcomes were shown to be dependent on severity of disease prior to treatment as measured by the amount of bacteria in the blood; 16 mg/kg of ETI-204 was determined to be the maximally efficacious dose.
A second presentation by Elusys demonstrated significant efficacy in two studies in monkeys. In both studies, obiltoxaximab was dosed via a single intramuscular injection (IM) at 16 mg/kg, 18-48 hours following challenge with aerosolized B. anthracis spores. Survival to day 28 or day 56 was the primary endpoint. In the first study, obiltoxaximab survival was 100%, 83% and 50% at 18, 24 and 36 hours compared to zero survival in the placebo group. In the second study, obiltoxaximab survival was 93%, 43%, and 25% at 24, 36 and 48 hours compared to 10% in placebo. IM obiltoxaximab was significantly efficacious compared to placebo when given at 18 and 24 hours post-exposure, and provided increased protection compared to controls at 36 and 48 hours post-exposure. Obiltoxaximab prevented development of Protective Antigen (PA) toxemia and bacteremia in the majority of animals when administered at 18 or 24 hours post challenge, and effectively neutralized serum PA in animals treated at 36 and 48 hours post challenge.
"Elusys is pleased to be presenting important data on the efficacy and pharmacology of obiltoxaximab," said Elizabeth Posillico, PhD, President and Chief Executive Officer of Elusys. "We have completed the nonclinical efficacy studies required for filing our biologics license application and are delighted and confident that our BLA will be submitted in the coming weeks. We believe that obiltoxaximab can be an important addition to the Strategic National Stockpile to help protect the U.S. public from this deadly bioterror threat."