Abrilumab (AMG 181) in Adults With Moderate to Severe Crohn's Disease

The primary objective of this study is to evaluate the efficacy of abrilumab as measured by the proportion of participants achieving Crohn's Disease Activity Index (CDAI) remission (CDAI \< 150) after treatment for 8 weeks.

The study consisted of a 24-week double-blind treatment period, a 108-week open-label treatment period, and a 2-year safety follow-up period.

Participants who did not reach minimal improvement, or experienced disease worsening after initial response, had the option to receive open-label abrilumab 210 mg every 3 months (Q3M) beginning at double-blind period week 12 or after. Not reaching minimal improvement was defined as not having an improvement in CDAI score of ≥ 70 points from baseline on 2 consecutive visits (at or after week 8) at least 2 weeks apart. Disease worsening after week 8 (or week 12) response was defined as having an increase in CDAI score of ≥ 70 points from the week 8 (or week 12) CDAI score on 2 consecutive visits at least 2 weeks apart, and a CDAI score of \> 150.

Participants were planned to be randomized in a 2:1:2:1 ratio to SC placebo or abrilumab at 21 mg, 70 mg (on day 1, week 2, week 4, and every 4 weeks thereafter until week 24), or 210 mg (on day 1 followed by placebo in weeks 2 and 4 and every 4 weeks thereafter until week 24), respectively. Due to a consistent discrepancy between the investigational product (IP) instruction manual (IPIM) description of vial positions and the actual vial positions in the IP package participants were initially randomized to 3 arms (placebo, 70 mg, and 210 mg) with a randomization ratio of 3:2:1. The study was temporarily paused while this issue was investigated. Once the discrepancy was corrected, Protocol Amendment 3 implemented, and affected participants completed their double-blind treatment period, the study resumed enrollment and randomization per protocol. Neither the randomization nor study blind was compromised and therefore the intent-to-treat principle was maintained.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosed with ileal, ileo-colonic, or colonic Crohn's disease for a minimum of 6 months prior to baseline
* Moderately to severely active Crohn's disease defined by a CDAI score ≥ 220 and ≤ 450 at baseline
* Evidence of active inflammation within 12 weeks prior to baseline
* Demonstrated an inadequate response to, loss of response to, or intolerance to at least one of the following agents: Immunomodulators and/or anti-tumor necrosis factor (TNF) agents or to corticosteroids (non-US sites only).
* Neurological exam free of clinically significant, unexplained signs or symptoms during screening and no clinically significant change prior to randomization
* Subject has no known history of active tuberculosis and has a negative test for tuberculosis during screening

Exclusion Criteria:

* Short bowel syndrome
* Stricture with obstructive symptoms within 3 months
* Bowel surgery within 12 weeks prior baseline, or has planned bowel surgery within 24 weeks from baseline
* Ileostomy and/or colostomy
* Any gastric or intestinal pouch
* Evidence of an infected abscess
* Bowel perforation or evidence of non-inflammatory obstruction during the 6 months prior to baseline
* Stool positive for C. difficile toxin at screening
* Any uncontrolled or clinically significant systemic disease
* Known to have tested positive for hepatitis B virus surface antigen, hepatitis C virus antibody, or human immunodeficiency virus (HIV)
* Any underlying condition that predisposes subject to infections
* Subject has malignancy (other than resected cutaneous basal or cutaneous squamous cell carcinoma, or treated in situ cervical cancer considered cured) within 5 years of baseline
* Received an anti-TNF agent, cyclosporine, mycophenolate mofetil, sirolimus (rapamycin), thalidomide, tacrolimus, topical (rectal) aminosalicylic acid (eg, mesalamine) or topical (rectal) steroids, intravenous or intramuscular corticosteroids within protocol-specified time periods.
* Any prior exposure to antagonists of integrins or integrin ligands (eg, natalizumab, efalizumab, or vedolizumab), rituximab, or TNF kinoid immunotherapies, AMG 181, or any form of cell-based transplantation
* Received treatment of infection with intravenous (within 30 days of baseline) or oral (within 14 days prior to baseline) antibiotics, antivirals, or antifungals
* Significant laboratory abnormalities
* Pregnant or breast feeding