Mavrilimumab (CAM 3001) is a monoclonal antibody with antiviral activity that has an affinity for the α subunit of the granulocytic-macrophage colony-stimulating factor (GM-CSF) receptor and blocks downstream intracellular signaling of GM-CSF. GM-CSF may be associated with an overactive inflammatory response associated with respiratory failure and death, and could be used to study rheumatoid arthritis.