Plasma concentration of cf-nDNA in RA treated with tocilizumab or TNF-I. Time course of plasma cf-nDNA treated with tocilizumab (TCZ) (A) and TNF-I (B). qPCR for cf-nDNA concentration using primers against 115-bp ALU repeats. ***P < 0.001; n.s.: not significant (Mann–Whitney U test). Time course of plasma cf-nDNA treated in biological treatment-naïve (bio-naïve) patients with TCZ (C) and TNF-I (D). **P < 0.01; n.s.: not significant (Mann–Whitney U test). (E, G) Plasma cf-nDNA concentration in bio-naïve patients (remission or active disease) at week 12 treated with TCZ (C) or TNF-I (E). **P < 0.01; n.s.: not significant (Mann–Whitney U test). (F, H) cf-nDNA and DAS28ESR correlations at week 12 in bio-naïve patients treated with TCZ (D) or TNF-I (F). Straight line: regression line, grey area: 95% confidence interval, Spearman’s rank correlation coefficient