The invention relates to methods and compositions for treating undifferentiated arthritis (UA) and/or preventing the development of rheumatoid arthritis (RA) in subjects with UA by administering to a subject in need thereof an effective amount of soluble CTLA4 molecule.本發明係關於藉由向有需要之病患投與有效量之可溶性CTLA4分子來治療未分類關節炎(UA)及/或預防患有UA之病患發生風濕性關節炎(RA)之方法及組合物。