%0 Journal Article %T Efficacy of Abatacept for Arthritis in Patients with an Overlap Syndrome between Rheumatoid Arthritis and Systemic Lupus Erythematosus %A Kei Ikeda %A Yoshie Sanayama %A Sohei Makita %A Junichi Hosokawa %A Mieko Yamagata %A Daiki Nakagomi %A Katsuhiko Takabayashi %A Hiroshi Nakajima %J Journal of Immunology Research %D 2013 %R 10.1155/2013/697525 %X Introduction. This study aimed to investigate the efficacy of abatacept for arthritis in patients with rhupus, an overlap syndrome between rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Methods. Patients who fulfilled both the 2010 ACR/EULAR criteria for RA classification and the 1997 ACR revised criteria for classification of SLE and received abatacept treatment for arthritis were retrospectively studied. Results. Six rhupus patients who fulfilled the inclusion criteria above were identified. All patients had active arthritis despite receiving antirheumatic drugs including methotrexate when abatacept was initiated. Clinical Disease Activity Index (CDAI) significantly decreased between baseline and 12 weeks ( ) and remained low through 24 weeks. All patients achieved either a good or moderate response according to the EULAR response criteria at 24 weeks. Health Assessment Questionnaire-Disability Index (HAQ-DI) also significantly decreased between baseline and 24 weeks ( ). In addition, the levels of immunoglobulin G and anti-DNA antibody significantly decreased between baseline and 24 weeks ( and , resp.). Conclusions. Treatment with abatacept is likely to be efficacious in patients with rhupus whose arthritis is refractory to methotrexate. In addition, abatacept may have a moderate effect on abnormal antibody production in rhupus patients. 1. Introduction The clinical coexistence of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) is a rare occurrence frequently referred to as ¡°rhupus syndrome¡± [1]. Increasing evidence suggests that arthritis in patients with rhupus can cause joint damage indistinguishable from that of RA, requiring aggressive treatment [2¨C5]. However, TNF antagonists, which are the most potent agents in preventing joint damage in RA when used in combination with methotrexate (MTX), can induce production of autoantibodies characteristic to SLE such as antinuclear antibodies (ANA) or anti-DNA antibodies [6, 7]. Less frequently but more importantly, TNF antagonists can cause lupus manifestations in RA [6¨C10] and rhupus syndrome [11]. Abatacept is a fully human, soluble fusion protein that consists of the extracellular domain of human cytotoxic T-lymphocyte antigen 4 (CTLA-4) and the Fc portion of IgG1, which selectively modulates the CD80/CD86:CD28 costimulatory signals and interactions between activated T cells and antigen presenting cells (APCs). The use of abatacept in patients with RA is associated with sustained efficacy both in disease activity and in radiographic progression without inducing %U http://www.hindawi.com/journals/jir/2013/697525/