An injectable formulation composed of opebacan, a 21 kDa recombinant fragment of human bactericidal/permeability-increasing protein (BPI), with potential anti-infective activity. Upon intravenous administration, opebacan is able to mimic BPI and binds to and neutralizes lipopolysaccharides (LPS or endotoxins), which are components of the cell wall of gram-negative bacteria that induce a potent innate immune response. This may prevent an endotoxin-mediated inflammatory response and may prevent graft-versus-host-disease (GvHD) after myeloablative allogeneic hematopoietic stem cell transplantation (aHSCT). BPI, a host-defense protein against microbial infection, is naturally produced by neutrophils. Chemotherapy and radiation therapy induce neutropenia and depletion of endogenous BPI. These therapies also cause intestinal damage and release of bacterial endotoxins into the bloodstream, which initiate a systemic inflammatory response, activate donor T-lymphocytes and possibly cause GvHD following aHSCT.