Circulating Th17.1 cells as candidate for prediction of therapeutic response to abatacept in patients with rheumatoid arthritis: exploratory research

T helper 17.1 cells (Th17.1) are highly pathogenic T cells in inflammatory diseases. This study aimed to identify Th cell biomarkers, including the analysis of Th17.1, that predict therapeutic response to abatacept in patients with rheumatoid arthritis. The circulating Th subsets among CD4+ T lymphocytes in 40 patients with rheumatoid arthritis before abatacept treatment were determined using multicolor flow cytometry. All patients received abatacept treatment for 24 weeks, and the change in disease activity score, including 28-joint count C-reactive protein, and the responsiveness of other indices to abatacept treatment were evaluated according the European League Against Rheumatism criteria [good responders, moderate responders, and non-responders]. The correlation between the abatacept responses and the Th subsets (baseline) was analyzed. Logistic regression analysis with inverse probability weighting method was conducted to calculate odds ratio adjusted for patient characteristics. The proportion of baseline Th17.1 cells was significantly lower in patients categorized as good responders than in those categorized as non-good responders (moderate responders and non-responders; p = 0.0064). The decrease in 28-joint count C-reactive protein after 24 weeks of abatacept therapy also showed a significant negative correlation with the proportion of Th17.1 cells. The adjusted odds ratio for achieving good response in patients with baseline Th17.1 level below the median value was 14.6 (95% confidence interval, 2.9-72.3; p = 0.0021) relative to that in the remaining patients. The proportion of Th17.1 cells at baseline is a good candidate for the prediction of response to abatacept treatment. These novel findings may represent an important step in the pursuit of precision medicine.