Elubrixin (SB-656933) is a CXCR2 antagonist that demonstrates dose-dependent effects on neutrophil activation and recruitment. In preclinical studies, the compound was shown to inhibit CXCL1-induced CD11b up-regulation on PMNs in an in vitro whole blood assay and to be active in in vivo rodent inhalation challenge models of airway inflammation that used endotoxin and ozone to induce airway neutrophilia. Elubrixin was being developed by GlaxoSmithKline for the treatment of chronic obstructive pulmonary disease, cystic fibrosis and ulcerative colitis. Elubrixin was withdrawn from the Phase II trial due to the lack of efficacy.