Tosatoxumab (AR-301; KBSA301), a human immunoglobulin G1 monoclonal antibody, specifically targets and neutralizes S. aureus alpha-toxin (alpha-hemolysin; Hla) by binding to its N-terminal epitope. This interaction blocks the toxin's ability to form functional pore oligomers, crucial for its pathogenic activity. As a result, Tosatoxumab offers promising potential as an adjunctive passive immunotherapy alongside conventional antibiotics for S. aureus pneumonia [1] [2].