Treatment of rheumatoid arthritis after regression of lymphoproliferative disorders in patients treated with methotrexate: a retrospective, multi-center descriptive study.

OBJECTIVES: To identify the optimal treatment for rheumatoid arthritis (RA) after the regression of lymphoproliferative disorders (LPDs). METHODS: The subjects were 232 patients with RA who developed LPD between 2000 and 2017 at seven hospitals participating in the LPD-WG study. Kaplan-Meier and Cox proportional regression analyses were performed to determine the factors associated with the rate of LPD relapse and the retention of biological disease-modifying antirheumatic drugs (bDMARDs). RESULTS: Treatment for RA was resumed in 138 patients after spontaneous regression of LPD after the discontinuation of methotrexate and in 52 patients after chemotherapy for LPD (persistent-LPD). LPD relapses occurred in 23 patients. Not DMARDs use but Hodgkin's lymphoma was identified as a risk factor for LPD relapse. In 88 RA patients treated with bDMARDs [tocilizumab, 39 patients; abatacept 20 patients; tumor necrosis factor inhibitor, 29 patients], the one-year retention rate was 67.8%. The risk factors for discontinuation of bDMARDs were persistent-LPD, non-diffuse large B-cell lymphomas (non-DLBCL), and a high clinical disease activity index (CDAI). Tocilizumab showed the highest retention rate among bDMARDs, particularly in DLBCL. CONCLUSION: Although any bDMARD could be used in patients after LPD regression, effectiveness and risk for relapse should be carefully assessed for each LPD subtype.