Anthim (obiltoxaximab) injection approved for treatment of inhalational anthrax

On Friday, March 18, the U.S. Food and Drug Administration approved Anthim (obiltoxaximab) injection to treat inhalational anthrax in combination with appropriate antibacterial drugs. Anthim is also approved to prevent inhalational anthrax when alternative therapies are not available or not appropriate.

Inhalational anthrax is 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. It is caused by breathing in the spores of the bacterium Bacillus anthracis. When inhaled, the anthrax bacteria replicate in the body and produce toxins that can cause massive and irreversible tissue injury and death. Anthrax is a potential bioterrorism threat because the spores are resistant to destruction and can be spread by release in the air.

"As preparedness is a cornerstone of any bioterrorism response, we are pleased to see continued efforts to develop treatments for anthrax," said Edward Cox, M.D., M.P.H, director of the Office of Antimicrobial Products in FDA's Center for Drug Evaluation and Research.

Anthim is a monoclonal antibody that neutralizes toxins produced by B. anthracis. Anthim was approved under the FDA's Animal Rule, which allows efficacy findings from adequate and well-controlled animal studies to support FDA approval when it is not feasible or ethical to conduct efficacy trials in humans.

Anthim's effectiveness for treatment and prophylaxis of inhalational anthrax was demonstrated in studies conducted in animals based on survival at the end of the studies. More animals treated with Anthim lived compared to animals treated with placebo. Anthim administered in combination with antibacterial drugs resulted in higher survival outcomes than antibacterial therapy alone.

The safety of Anthim was evaluated in 320 healthy human volunteers. 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 carries a Boxed Warning alerting patients and health care providers that the drug can cause allergic reactions (hypersensitivity), including a severe reaction called anaphylaxis. Anthim 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.

Anthim was developed by Elusys Therapeutics, Inc. of Pine Brook, New Jersey, in conjunction with the U.S. Department of Health and Human Services' Biomedical Advanced Research and Development Authority.