A Study of Efficacy and Safety of Mongersen (GED-0301) for the Treatment of Adult and Adolescent Subjects With Active Crohn's Disease

Inclusion Criteria: Subjects must satisfy the following criteria to be enrolled in the study: * Male or female ≥ 12 years * Subject is able to swallow the IP tablets * Active Crohn's disease (CD) disease as determined by the Crohn's Disease Activity Index (CDAI) score and the Simple Endoscopic Score for Crohn's Disease (SES-CD) * Must meet a determined average minimum number of daily stools or rating of abdominal pain over a 7day period * Subject must have failed or experienced intolerance to at least one of the following: budesonide; systemic corticosteroids; immunosuppressants (eg, azathiopurine, 6-mercaptopurine, or methotrexate); or biologics for the treatment of CD (ie, infliximab, adalimumab, certolizumab, or vedolizumab). Exclusion Criteria: • The presence of any of the following will exclude a subject from enrollment: Diagnosis of ulcerative colitis (UC), indeterminate colitis, ischemic colitis, microscopic colitis, radiation colitis or diverticular disease-associated colitis, or colitis due to immunodeficiency * Local manifestations of Crohn's Disease (CD) such as abscesses, short bowel syndrome; or other disease complications for which surgery might be indicated or could confound the evaluation of efficacy * Subject has strictures with prestenotic dilatation, requiring procedural intervention, or with obstructive symptoms. In addition, subjects with colonic strictures that are not passable with an age-appropriate colonoscope, or strictures in the ileum or ileocecal valve that are fibrotic in nature, will be excluded * Intestinal resection within 6 months or any intra-abdominal surgery within 3 months prior to the Screening Visit * Ileostomy or a colostomy * Subject has a history of any clinically significant medical condition that, in the investigator's opinion, would prevent the subject from participating in the study * Adolescents with delayed growth or pubertal development who are on corticosteroids at baseline and who should not continue treatment with the same dose of corticosteroids until the Week 12 visit.