US regulators have green lighted a new treatment for inhalation anthrax, a rare disease that can occur after exposure to infected animals or contaminated animal products, or as a result of an intentional release of anthrax spores.

When inhaled, anthrax bacteria replicate in the body and produce toxins that can cause massive and irreversible tissue injury and death. The spores are resistant to destruction and can be spread by release in the air, making Anthrax an attractive target for use in bioterrorism.

Elusys Therapeutics’ Anthim (obiltoxaximab) is a monoclonal antibody has been designed to neutralise the toxins produced by anthrax, approved for both treatment and prophylaxis via the FDA’s Animal Rule, which allows efficacy findings from adequate and well-controlled animal studies to support marketing clearance when it is not feasible or ethical to conduct efficacy trials in humans.

Trials showed that more animals treated with Anthim lived compared to animals treated with placebo, and that administering the injection in combination with other antibacterial drugs boosted survival outcomes. The drug was also evaluated in 320 healthy human volunteers, which found the most frequently reported side effects were headache, itching (pruritus), upper respiratory tract infections, cough, nasal congestion, hives, and bruising, swelling and pain at the infusion site.

Anthim does carry a boxed warning alerting patients and healthcare providers that it can cause allergic reactions, including anaphylaxis, and thus should be administered in settings where patients can be monitored and treated for anaphylaxis. “However, given that anthrax is a very serious and often deadly condition, the benefit of Anthim for treating anthrax is expected to outweigh this risk,” the FDA said.

“As preparedness is a cornerstone of any bioterrorism response, we are pleased to see continued efforts to develop treatments for anthrax,” noted Edward Cox, director of the Office of Antimicrobial Products in FDA’s Center for Drug Evaluation and Research.