Rovelizumab, also known as LeukArrest and Hu23F2G, is a humanized monoclonal antibody which was an experimental immunosuppressive drug. Rovelizumab was developed by Icos to treat patients suffering from haemorrhagic shock. The drug is a monoclonal antibody that suppresses white blood cells which become overly active during shock. During testing the number of patients given the drug was low because rovelizumab had to be delivered within four hours of the injury and consent was required. Often the patient was unconscious and relatives had to be reached to give consent. In June 1998, Icos and many medical centers asked the United States Food and Drug Administration (FDA) to waive consent requirements in situations where the patient was at high risk of dying and relatives could not be reached.