Remarkable efficacy of tocilizumab for treating rheumatoid arthritis in patients with high platelet counts

Objectives. To optimize the efficacy of treatment with tocilizumab for rheumatoid arthritis (RA), we comparatively analyzed the outcome of tocilizumab treatment in patients with normal background changes associated closely with IL-6. Patients and Methods. The study involved 87 patients with RA satisfying the diagnostic criteria of the American College of Rheumatology (ACR) and receiving continuous tocilizumab treatment for 24 weeks or longer. The outcome of tocilizumab treatment in these patients was comparatively analyzed in relation to the baseline platelet count (the high platelet count group and the normal group), pretreatment hemoglobin levels (the low group and the normal platelet count group), and speed of bone destruction (the rapid progression group and slow progression group). Results. Treatment with tocilizumab significantly improved the 28-joint disease activity score using the erythrocyte sedimentation rate (DAS28-ESR) and Clinical Disease Activity Index (CDAI), regardless of baseline platelet count, hemoglobin level, or annual speed of bone destruction (Delta TSS). The margins of improvement in DAS28-ESR and CDAI did not differ depending on baseline hemoglobin level or Delta TSS, but the improvement was significantly greater in the high platelet count group than in the normal platelet count group. Conclusions. These results suggest that in patients with high platelet count, IL-6 is a more important factor involved in RA pathogenesis and that tocilizumab is suitable as a first-line biologic for the treatment of RA patients with high platelet count.