“…Such differences may be related to different dosing schedules (taking into account the weight (here and [20]) or not [16] for TCZ), as well as the various analytical methods used to quantify the mAbs. Here, we used a highly specific LC-MS/MS method, adapted from our previously published method [27,30], whereas other studies used various ELISA methods [16,20,36,43], for which the analytical limits have been well-described [25,28,44,45]. For example, Mazilu et al used the Promonitor â assay, for which a large bias was found relative to our LC-MS/MS method (mean underestimation of RTX concentration of 69%) or the Lisa-tracker â kit [30].…”