Background In recent years, biological agents are widely used for the treatment of rheumatoid arthritis (RA) and there are several registries for the treatment of RA in other countries. However, in Japan, these studies are limited. Now, we set up the registry of RA patients treated using biological agents named Tsurumai Biologics Communication (TBC) and collected 2072 cases until now . Abatacept is recognized as one of the treatment for RA patients with no effect of anti-TNF agents by EULAR recommendation  and it is used in more than 50 countries. It came to be used newly in Japan since September, 2010.
Objectives Clinical Phase II trials in Japan, ACR improvement rates, compared with placebo showed significantly improvement in the group of ABT (abatacept) 2 mg/kg and 10 mg/kg.
The purpose of this research was to evaluate the patient who reduced the dose of ABT by 250mg (5 mg/kg).
Methods The efficacy, safety, continuity were evaluated of 15 cases in TBC registry which treat half amount (250 mg) dose of ABT.Background Patients - average age 60.1 and average disease duration 12.4 years, 12 females, 3 males, 53.7kg average body weight, the dosage is 5.3mg/kg body weight in terms of average, 13 cases combined with MTX, 13 cases of Bio naive.
Results Disease activities before the start of treatment, 6 patients were high disease activity, 3 patients were moderate disease activity, 1 patients were low disease activity,and 5 patient was remission.
At 24 weeks after treatment, 5 patients because of inadequate response, which was continued back to the normal dose, 10 cases were continued at half dose, all patients confirmed the improvement in disease activity.
Serious adverse events in all 15 cases have not been observed.
Conclusions In our reports, half dose of ABT treatment is potentially as an alternative treatment to the patients such as elderly patients or in response to economic reasons.
Kojima T, et al. Mod Rheumatol. 2011 [Epub ahead of print].
Osef S et al. Ann Rheum Dis 2010 69:964-975.
Disclosure of Interest None Declared