Pharmacokinetics
The PK analysis set comprised 26 patients in the SAR200 + 26W taper group and 14 patients in the SAR150 + 26W taper group. All pre-dose concentrations of functional sarilumab in serum at week 0 were below the lower limit of quantification (312.5 ng/mL). After multiple SC administrations of sarilumab, the observed trough concentrations of functional sarilumab increased over time from week 0 through week 52 in sarilumab groups. At week 24, the mean trough concentration of functional sarilumab increased 2.7-fold with a 1.3-fold increase in dose. There was an accumulation of sarilumab following SC administrations of sarilumab 150 and 200 mg, with the accumulation ratio of ~ 9-fold based on the mean trough concentrations (Additional file 