Background/Purpose:

The multi-biomarker disease activity (MBDA) score assessed with 0.2 mL serum has been reported as a novel composite disease activity index for patients with rheumatoid arthritis (RA). We reported the correlation of MBDA score with conventional composite measures such as DAS28 in patients with RA. However, the estimation of the MBDA score in RA patients treated with anti-IL-6 receptor antibody tocilizumab (TCZ) has not been investigated. Purpose of this study is to clarify if the MBDA score could reflect disease activity and track therapeutic effect including clinical and radiographic outcomes in RA patients treated with TCZ.

Methods:

Fifty two RA patients who treated with TCZ were enrolled. The MBDA algorithm combines 12 serum biomarkers (VCAM-1, EGF, VEGF-A, IL-6, TNF-RI, MMP-1, MMP-3, YKL-40, Leptin, Resistin, CRP, SAA) into a single score from 1-100 according the Vectra™ DA algorithm. MBDA disease activity categories were defined as high (HDA>44), moderate (MDA>29≤44), low (LDA<25≤29) and remission (REM≤25). Radiographic changes were assessed by the modified total Sharp score (mTSS). For statistic analysis, Spearman's rank correlation coefficients and Pearson's chi-square test were used. All p-values are two sided and <0.05 were considered significant.

Results:

At baseline (BL), patients had median age of 57±18, disease duration of 12.4±11.2 years, DAS28 of 5.6±1.3, CDAI of 22.1±12.2, HAQ-DI of 1.4±0.9 and mTSS of 106±112. MTX was used in 86.5% and positivity of RF was 78.8%. MBDA score at BL was 57.7±19.2 and were correlated well with DAS28 and CDAI (ρ=0.63 and 0.57, respectively, p<0.0001). TCZ improved MBDA score from 57.7 to 43.7 and 42.5 at W24 and W52, respectively, DAS28 from 5.6 to 2.5 and 2.9, CDAI from 22.2 to 6.4 and 5.6, at BL, W24 and W52, respectively. Changes of MBDA from BL to 52W by TCZ were significantly correlated with those of DAS28 (r=0.471, p<0.001) and CDAI (r=0.373, p<0.01). MBDA-REM ratio at W52 was significantly correlated with DAS28-REM ratio (AUROC=0.643) and CDAI-REM ratio (0.768). Yearly progression of mTSS (ΔmTSS) was improved from 12.3±14.9 to 0.5±2.5 by TCZ and 77% achieved ΔmTSS<0. Interestingly, all patients who achieved MBDA-LDA (8), MBDA-REM (3) or Boolean-REM (5) at W24 showed ΔmTSS<0.5, whereas some of DAS28-REM and CDAI-REM did ΔmTSS>0.5. Patients who achieved MBDA-REM or Boolean-REM at W24 revealed higher likelihood ratio for achieving both radiographic and functional REM at W52 than those who DAS28-REM and CDAI-REM. 

Conclusion:

This is the first report of the MBDA estimated in RA patients treated with TCZ. TCZ efficiently improved MBDA score and BL and changes of MBDA were correlated with those of conventional composite measures. Although additional data are needed to assess the relationship between MBDA and radiographic and functional remission, The MBDA score reflects disease activity and tracks therapeutic effects and MBDA-REM might be preferable to DAS28-REM for predicting good outcome in both radiographic damage and physical function in RA patients treated with TCZ.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-multi-biomarker-disease-activity-vectra-da-algorithm-score-reflects-clinical-disease-activity-and-structural-changes-in-rheumatoid-arthritis-patients-treated-with-tocilizumab/