raxibacumab + obiltoxaximab

**Raxibacumab + obiltoxaximab** is a combination of two monoclonal antibodies approved for the treatment and prophylaxis of inhalational anthrax due to *Bacillus anthracis*. Raxibacumab, a human IgG1λ monoclonal antibody, and obiltoxaximab, a chimeric IgG1 kappa monoclonal antibody, both neutralize anthrax toxins by binding to **protective antigen (PA)**, preventing its interaction with host cell receptors (ANTXR1/2) and blocking translocation of lethal factor (LF) and edema factor (EF) into cells. This combination is used with antibacterial drugs like ciprofloxacin or levofloxacin for treatment, and when alternatives are unavailable for prevention; both were developed under FDA Animal Rule based on rabbit and macaque survival data, with raxibacumab originally by Human Genome Sciences (acquired by GSK) and obiltoxaximab by Elusys Therapeutics.