The purpose of this study was to determine how effective and safe the study drug Olokizumab was in patients with Rheumatoid Arthritis (RA) who had been already receiving, but not fully responding to treatment with methotrexate (MTX).

The primary objective of this study was to evaluate the efficacy of olokizumab (OKZ) 64 mg administered subcutaneously (SC) once every 2 weeks (q2w) or once every 4 weeks (q4w) relative to placebo in subjects with moderately to severely active rheumatoid arthritis (RA) inadequately controlled by methotrexate (MTX) therapy.

The goal of this Phase III study was to assess the efficacy, tolerability, and safety of OKZ in subjects with moderately to severely active RA who had responded inadequately to MTX. The primary endpoint of the trial was at Week 12. Olokizumab was expected to reduce the disease activity and improve physical function. The study was expected to provide safety information in a large group of subjects over at least a 24 week period.

The CREDO 1 study included a 4-week Screening Period, a double-blind Treatment Period from Week 0 to Week 24, and a Safety Follow-Up Period from Week 24 to Week 44.

At randomization, a total of 428 eligible subjects were randomly assigned to 1 of 3 treatment groups in a 1:1:1 ratio:

1. OKZ 64 mg q4w: SC injection of OKZ 64 mg q4w (alternating with SC injection of placebo OKZ q4w to maintain blinding) + MTX.
2. OKZ 64 mg q2w: SC injection of OKZ 64 mg q2w + MTX.
3. Placebo: SC injection of placebo q2w + MTX

Throughout the double-blind Treatment Period, all subjects were required to remain on a stable dose of background 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, and concomitant treatment with folic acid ≥5 mg per week or equivalent is required for all subjects. The last dose of study treatment (OKZ or placebo) was at Week 22 in all groups.

Following Visit 2 (randomization), subjects returned to the study site at least every other week through Week 24 for response and safety assessments as per the study Schedule of Events.

Subjects were classified in terms of their response to study treatment at Week 14, with non-responders defined as subjects in any treatment group who had not improved by at least 20% in both swollen and tender joint counts (66-68 joint assessment). Starting at or as close as possible to Week 14, non-responders were administered sulfasalazine and/or hydroxychloroquine as rescue medication in addition to the assigned treatment.

After completion of the 24-week double-blind Treatment Period, subjects either rolled over into the long-term open-label extension (OLE) study or entered the Safety Follow-Up Period. During the Safety Follow-Up Period, subjects returned for visits +4, +8, and +22 weeks after the last dose of study treatment.

Subjects who discontinued the randomized treatment prematurely were required to come for the End of Treatment (EoT) Visit 2 weeks after the last study treatment administration and then continued with the scheduled study visits as per the Schedule of Events.

The study was conducted at approximately 50 sites across 4 countries globally, which included Russia, Belarus, Turkey, and Bulgaria.

Inclusion Criteria:

Subjects may be enrolled in the study only if they meet all of the following criteria:

• Subjects willing and able to sign informed consent

• Subjects must have a diagnosis of adult onset RA classified by ACR/EULAR 2010 revised classification criteria for RA for at least 12 weeks prior to Screening.

• Inadequate response to treatment with MTX for at least 12 weeks prior to Screening at a dose of 15 to 25 mg/week (or ≥10 mg/week if intolerant to higher doses).

  • The dose and means of administering MTX must have been stable for at least 6 weeks prior to Screening.

• Subjects must be willing to take folic acid or equivalent throughout the study

• Subjects must have moderately to severely active RA disease as defined by all of the following:

  • ≥6 tender joints (68 joint count) at Screening and baseline; and
  • ≥6 swollen joints (66 joint count) at Screening and baseline; and
  • CRP above ULN at Screening based on the central laboratory results.

Exclusion Criteria:

• Diagnosis of any other inflammatory arthritis or systemic rheumatic disease (e.g., gout, psoriatic or reactive arthritis, Crohn's disease, Lyme disease, juvenile idiopathic arthritis, or systemic lupus erythematosus). However, subjects could have secondary Sjogren's syndrome or hypothyroidism

• Subjects who were Steinbrocker class IV functional capacity (incapacitated, largely or wholly bed-ridden or confined to a wheelchair, with little or no self-care)

• Prior exposure to any licensed or investigational compound directly or indirectly targeting IL-6 or IL-6R (including tofacitinib or other Janus kinases and spleen tyrosine kinase [SYK] inhibitors)

• Prior treatment with cell-depleting therapies, including anti-CD20 or investigational agents (e.g., CAMPATH, anti-CD4, anti-CD5, anti-CD3, and anti-CD19)

• Prior use of bDMARDs, with the following exception:

  • Subjects who discontinued TNFi therapy due to a reason other than lack of efficacy were allowed to enter the study (TNFi therapy was not to be discontinued to facilitate a subject's participation in the study but should instead have been previously discontinued as part of a subject's medical management of RA). The use of TNFi therapy within the following windows prior to baseline was exclusionary:

  1. 4 weeks for etanercept
  2. 8 weeks for infliximab
  3. 10 weeks for adalimumab, certolizumab, and golimumab

• Use of parenteral and/or intra-articular glucocorticoids within 4 weeks prior to baseline

• Use of oral glucocorticoids greater than 10 mg/day prednisone (or equivalent), or change in dosage within 2 weeks prior to baseline

• Prior documented history of no response to hydroxychloroquine and sulfasalazine

• Prior use of cDMARDs (other than MTX) within the following windows prior to baseline (cDMARDs were not to be discontinued to facilitate a subject's participation in the study, but should instead have been previously discontinued as part of a subject's medical management of RA):

  1. 4 weeks for sulfasalazine, azathioprine, cyclosporine, hydroxychloroquine, chloroquine, gold, penicillamine, minocycline, or doxycycline
  2. 12 weeks for leflunomide unless the subject has completed the following elimination procedure at least 4 weeks prior to baseline: Cholestyramine at a dosage of 8 grams 3 times daily for at least 24 hours, or activated charcoal at a dosage of 50 grams 4 times daily for at least 24 hours
  3. 24 weeks for cyclophosphamide

• Vaccination with live vaccines in the 6 weeks prior to baseline or planned vaccination with live vaccines during the study

• Participation in any other investigational drug study within 30 days or 5 times the terminal half-life of the investigational drug, whichever is longer, prior to baseline

• Other treatments for RA (e.g., Prosorba Device/Column) within 6 months prior to baseline

• Use of intra-articular hyaluronic acid injections within 4 weeks prior to baseline

• Use of non-steroidal anti-inflammatory drugs (NSAIDs) on unstable dose or switching of NSAIDs within 2 weeks prior to baseline

• Previous participation in this study (randomized) or another study of OKZ

• Subjects with acute or chronic viral hepatitis B or C infection as detected by blood tests at Screening (e.g., positive for hepatitis B surface antigen [HBsAg], total hepatitis B core antibody [anti-HBc], or hepatitis C virus antibody [HCV Ab])

  a. Subjects who were positive for hepatitis B surface antibody (anti-HBs), but negative for HBsAg and anti-HBc, were eligible

• Subjects with HIV infection

• Subjects with:

  1. Suspected or confirmed current active TB disease or a history of active TB disease
  2. Close contact (i.e., sharing the same household or other enclosed environment, such as a social gathering place, workplace, or facility, for extended periods during the day) with an individual with active TB within 1.5 years prior to Screening.

• Concurrent malignancy or a history of malignancy within the last 5 years (with the exception of successfully treated carcinoma in situ of the cervix and successfully treated basal cell carcinoma and squamous cell carcinoma not less than 1 year prior to Screening [and no more than 3 excised skin cancers within the last 5 years prior to Screening])

• Subjects with any infection requiring oral antibiotic or antiviral therapy in the 2 weeks prior to Screening or at baseline, injectable anti-infective therapy in the last 4 weeks prior to baseline, or serious or recurrent infection with a history of hospitalization in the 6 months prior to baseline

• Subjects with evidence of disseminated herpes zoster infection, zoster encephalitis, meningitis, or other non-self-limited herpes zoster infections in the 6 months prior to baseline

• Subjects with planned surgery during the study or surgery ≤4 weeks prior to Screening and from which the subject had not fully recovered, as judged by the Investigator

• Subjects with diverticulitis or other symptomatic GI conditions that might predispose the subject to perforations, including subjects with a history of such predisposing conditions (e.g., diverticulitis, GI perforation, or ulcerative colitis)

• Pre-existing central nervous system demyelinating disorders (e.g., multiple sclerosis and optic neuritis)

• History of chronic alcohol or drug abuse as judged by the Investigator

• Female subjects who are pregnant, currently lactating, have lactated within the last 12 weeks, or who were planning to become pregnant during the study or within 6 months of last dose of study treatment

• Female subjects of childbearing potential (unless permanent cessation of menstrual periods, determined retrospectively after a woman had experienced 12 months of natural amenorrhea as defined by the amenorrhea with underlying status [e.g., correlative age] or 6 months of natural amenorrhea with documented serum follicle-stimulating hormone levels >40 mIU/mL and estradiol <20 pg/mL) who were not willing to use a highly effective method of contraception during the study and for at least 6 months after the last administration of study treatment OR Male subjects with partners of childbearing potential not willing to use a highly effective method of contraception during the study and for at least 3 months after the last administration of study treatment;

• Subjects with a known hypersensitivity to any component of the OKZ drug product, or placebo

• Subjects with a known hypersensitivity or contraindication to any component of the rescue medication

• History of severe allergic or anaphylactic reactions to human, humanized, or murine monoclonal antibodies

The above information was not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.