Filgotinib maleate (GLPG0634 maleate) is a selective, orally available JAK1 inhibitor with anti-inflammatory and antiviral activities. Filgotinib maleate can effectively inhibit the activities of JAK1 , JAK2 , JAK3 and TYK2 with IC 50 values of 10 nM, 28 nM, 810 nM and 116 nM, respectively. Filgotinib maleate also inhibits HIV-1 driven gene transcription and reduces proliferation of HIV-1 infected cells. Filgotinib maleate can be used in the study of rheumatoid arthritis and inflammatory bowel disease.