To evaluate the effectiveness of tumor necrosis factor (TNF) inhibitors for the treatment of human T lymphotropic virus type I (HTLV-I)-positive patients with rheumatoid arthritis (RA) in an area endemic for HTLV-I infection.
We conducted an observational study of 585 RA patients in whom TNF inhibitors were newly introduced as a first biologic disease-modifying antirheumatic drug in an area in southwestern Japan that is endemic for HTLV-I infection.
Fifty patients (8.5%) were anti-HTLV-I antibody-positive. The ages of the patients in this group were significantly higher at entry compared with the ages of patients who were anti-HTLV-I antibody-negative (n = 535). The median Disease Activity Score in 28 joints using the erythrocyte sedimentation rate (DAS28-ESR) was 5.21. Among the total group of patients, 82% were anti-citrullinated protein antibody (ACPA)-positive. The persistence rate of TNF inhibitors at 24 weeks was 89%. The median DAS28-ESR was significantly decreased at 24 weeks in each group. The European League Against Rheumatism (EULAR) response rate was significantly better in the anti-HTLV-I antibody-negative patients (P = 0.0277). Multiple regression analysis demonstrated that anti-HTLV-I antibody status was significantly associated with the EULAR response rate and change in the DAS28-ESR and was prominent especially in the ACPA-negative subjects. No patients developed adult T cell leukemia/lymphoma (ATL) or HTLV-I-associated myelopathy (HAM) during the 24-week treatment period.
The efficacy of TNF inhibitors may be attenuated in anti-HTLV-I antibody-positive patients with RA. ATL and HAM did not develop when TNF inhibitors were used for 24 weeks, but the long-term risk is not known.