Objective: To investigate the response to and safety of anti–tumor necrosis factor (anti-TNF) therapy in human T lymphotropic virus type I (HTLV-I)–positive patients with rheumatoid arthritis (RA).
Methods: Therapeutic response was evaluated in 10 HTLV-I–positive and 20 HTLV-I–negative patients with RA (sex and age matched) at 3 months after the beginning of anti-TNF therapy using the European League Against Rheumatism improvement criteria. As secondary end points, the discontinuation rate of anti-TNF therapy and its safety, especially the development of adult T cell leukemia (ATL), were evaluated over a 2-year period.
Results: Significantly higher baseline levels of C-reactive protein (CRP) were observed in HTLV-I–positive patients than in HTLV-I–negative patients (P = 0.0003). The response rate to anti-TNF therapy was lower in HTLV-I–positive patients than in HTLV-I–negative patients. The median CRP level, erythrocyte sedimentation rate, and Disease Activity Score in 28 joints at 3 months after anti-TNF treatment in HTLV-I–positive patients were significantly higher than in HTLV-I– negative patients (P = 0.003, P = 0.03, and P = 0.003, respectively). The discontinuation rate due to insufficient response was significantly higher in HTLV-I–positive patients than in HTLV-I–negative patients (P = 0.013). During the 2-year observation period, no patients developed ATL.
Conclusion: These data suggest that HTLV-I–positive patients with RA had higher inflammation and greater resistance to anti-TNF treatment than HTLV-I–negative patients. Further study is necessary to determine whether HTLV-I infection should be measured when anti-TNF agents are administered to patients with RA, especially in areas were HTLV-I is endemic.