An Open-Label Extension Study Assessing the Long-Term Efficacy and Safety of ALX-0061 in Subjects With Rheumatoid Arthritis

This was a multicenter, open-label extension (OLE) Phase II study designed to evaluate the long-term efficacy and safety of ALX-0061 (i.e., vobarilizumab) administered subcutaneously (s.c.) in subjects with active rheumatoid arthritis (RA) who had completed the treatment and assessment period of one of the preceding Phase IIb studies with ALX-0061 (ALX0061-C201 and ALX0061-C202; placebo and ALX-0061 treatment arms only), and who achieved at least 20% improvement in swollen joint count (SJC) and/or tender joint count (TJC) (66/68 counts) compared to Baseline at the final visit of the preceding study (i.e., Week 24 for Study ALX0061-C201 and Week 12 for Study ALX0061-C202).

Eligible subjects received one of the following treatments during the preceding Phase IIb studies ALX0061-C201 and ALX0061-C202: * Study ALX0061-C201: * Placebo (+ methotrexate \[MTX\]), or * ALX-0061 75 mg every 4 weeks (q4w) (+ MTX), or * ALX-0061 150 mg q4w (+ MTX), or * ALX-0061 150 mg every 2 weeks (q2w) (+ MTX), or * ALX-0061 225 mg q2w (+ MTX), for 24 weeks * Study ALX0061-C202: * ALX-0061 150 mg q4w, or * ALX-0061 150 mg q2w, or * ALX-0061 225 mg q2w, for 12 weeks At the Week 24 (ALX0061-C201) or Week 12 (ALX0061-C202) visit of the previous study, informed consent was obtained from all subjects who were deemed potentially eligible for the OLE study, according to the inclusion and exclusion criteria. This was marked as the Week 0 visit of the C203 study. Of note, the Baseline time point in the analyses of this study was defined the Baseline value of the parent study. In this OLE study, eligible subjects received ALX-0061 150 mg s.c. injections, beginning at Week 0 and every 2 weeks thereafter, up to and including Week 102. Eligible subjects from the preceding study ALX0061-C201 also continued their MTX treatment. Maintenance of the response (i.e., at least 20% improvement in both SJC and TJC compared to Baseline of the preceding study) was reassessed at the study visits at Weeks 12, 24, 36, 48, 60, 72, 84, and 96. Subjects who failed to maintain response and met the Efficacy Discontinuation Criteria were discontinued from this study.