CSF2 and rheumatoid arthritis: In the Environment and Reproductive Health (EARTH) study 106, mavrilimumab modulated the pathophysiological pathways associated with RA, including acute‐phase proteins (CRP and IL‐6) and molecules involved in bone damage [matrix metalloproteinase‐3 (MMP3)], confirming that GM‐CSF acts upstream in the pathogenesis of RA.