This OLE study (CL04041024) included an 82-week open-label Treatment Period that followed completion of one of the core studies (Study CREDO 1, 2 or 3). The OLE open-label Treatment Period lasted from Visit 1 (OLE Baseline/Week 24) to Visit 10 (End of Treatment (EoT)/Week 106), followed by a 20-week Safety Follow-Up Period from Week 106 to Week 126. The first visit of the OLE study was the same visit as the Week 24 visit in the core studies.
Subjects were randomized to 1 of the 2 OKZ treatment groups in the OLE study based on the treatment received in the core studies. Subjects who had received OKZ (q2w or q4w) in the core study in which they had participated (including subjects who received placebo in Study CREDO 3 and were re-randomized to OKZ at Week 16) received the same OKZ treatment regimen in the OLE study. Subjects who had received placebo (Study CREDO 1 and CREDO 2) or adalimumab (Study CREDO 2) in the core study in which they had participated were randomized in a 1:1 ratio to OKZ 64 mg q2w or OKZ 64 mg q4w regimens in the OLE study.
For the first 12 weeks of the OLE, all subjects were required to remain on a stable dose of background methotrexate (MTX) at 15 to 25 mg/week (or≥10 mg/week if there was documented intolerance to higher doses) with a stable route of administration (oral, SC, or intramuscular (IM)). After 12 weeks (Visit 4 [Week 36] of the OLE study), the Investigator might adjust the MTX dosage and route, per local guidelines. Methotrexate might be adjusted only for safety reasons according to Investigator discretion before Visit 4 (Week 36) of the OLE study.
Subjects who had been on rescue disease-modifying anti-rheumatic drugs (DMARDs) during the core studies were asked to continue these medications for the first 12 weeks of the OLE study. The Investigator could adjust these background medications if deemed appropriate after Visit 4 (Week 36) of the OLE study. Background rescue therapy might be adjusted only for safety reasons according to Investigator discretion before Visit 4 (Week 36) of the OLE study.
Throughout the study, concomitant treatment with folic acid ≥ 5 mg per week or equivalent was required for all subjects.
Subjects returned to the study site periodically for safety and response assessments as per the Schedule of Events.
The last dose of open-label study treatment in the OLE study was administered at Week 104 for all subjects. After completion of the 82-week open-label Treatment Period, subjects entered the 20-week Safety Follow-Up Period. During the Safety Follow-Up Period, subjects returned for 3 visits at +4, +8, and +22 weeks after the last dose of study treatment.
Subjects who discontinued the open-label treatment prematurely required to come for the EoT Visit 2 weeks after the last study treatment administration and then return for the 3 Safety Follow-Up Visits +4, +8, and +22 weeks after the last study treatment administration.
Adverse events were assessed throughout the study period and evaluated using the Common Technology Criteria version 4.0 (CTCAE v 4.0).
There were ongoing monitoring of safety events, including laboratory findings by the Sponsor or its designee. In addition, safety parameters were assessed throughout the study by an independent Data Safety Monitoring Board (DSMB).