Figure 3. Natalizumab C_trough (A) and α4-Integrin Saturation on MNCs (B) for All Participants Who Had an MS Relapse.

^aRelapses are shown at the time of the visit closest to the recorded relapse. Five participants from the SID arm and 7 participants from the EID arm had relapse. Participant 06 from the EID arm had relapse at week 72, and there is no PD sample for this participant at this timepoint. In the overall population, mean serum natalizumab C_trough ranged from 10–21 μg/mL for Q6W and 33–38 μg/mL in Q4W participants. Mean trough % α-4 integrin saturation on MNCs remained above 65.5% in Q6W participants and above 77.9% in Q4W participants. C_trough = trough concentrations; EID = extended-interval dosing; MNC = mononuclear cells; PK = pharmacokinetic; Q4W = every 4 weeks; Q6W = every 6 weeks; SID = standard-interval dosing.