Introduction of biologics, Such as infliximab, to the therapy of rheumatoid arthritis (RA) patients has revolutionized the treatment of this disease. However, biomarkers for predicting the efficacy of the drug at an early phase of treatment for selecting real responders have not been found. We here present predictive markets based On a thorough transcriptome analysis of white blood cells from RA patients. RNA from whole blood cells of consecutive 42 patients before the first infusion was analyzed with microarrays for training Studies. Samples from the subsequent 26 consecutive patients were used for a prospective study. We categorized the results into no inflammation and residual inflammation groups using the serum C-reactive protein (CRP) level at 14 weeks after the first infusion. The accuracy of prediction in our study was 65.4%. (C) 2009 Elsevier Inc. All rights reserved.