Hu23F2G (23F2G, LeukArrestTM) is a humanised leukointegrin monoclonal antibody that is in phase II trials with ICOS Corporation and Abbott in the US for the treatment of trauma-induced haemorrhagic shock. ICOS has initiated a phase II study of Hu23F2G in patients with multiple sclerosis undergoing acute exacerbations. No significant clinical benefit was seen in this trial, however an additional phase II trial has been initiated using a multiple dosing regimen. Phase II trials in patients with myocardial infarction (MI) and in patients with ischaemic stroke have been completed. The study in patients with MI was being conducted by the Mayo Physician Alliance for Cardiovascular Trials, an affiliate of the Mayo Clinic in Rochester, USA. ICOS Corporation humanised the monoclonal antibody to the CD18 receptor on leukocytes and has exclusive rights to Hu23F2G in the USA. Abbott has exclusive rights to Hu23F2G outside the USA.ICOS is also investigating the potential of Hu23F2G in the treatment of cerebral vasospasm, head trauma and restenosis in preclinical studies. Hu23F2G may also have potential in the treatment of acute peripheral arterial occlusion and in the preservation of solid transplant organs; these indications are at the research stage of development.