Efficacy and Safety Study of Ontamalimab as Induction Therapy in Participants With Moderate to Severe Crohn's Disease (CARMEN CD 305)

Participants must be between greater than or equal to (\> =) 16 and less than or equal to (\<=) 80 years of age; participants less than (\<) 18 years of age must weigh \>=40 kg and must have body mass index \>=16.5 kilogram per meter square (kg/m\^2)

Participants must have active moderate to severe ileal (terminal ileum), ileocolic, or colonic CD at baseline (Visit 2) as defined by:

1. CDAI score between 220 and 450 (inclusive) AND

2. Meeting the following subscores in the 2 item PRO:

i. Abdominal pain subscore \>= 5 (average worst daily pain on the 11 point NRS) and abdominal pain subscore \>= 2 (average daily pain on the 4-point abdominal pain variable of CDAI) over the 7 most recent days out of the 10 days before colonoscopy preparation (may or may not be contiguous) AND/OR ii. Average of the daily stool frequency subscore \>=4 of type 6/7 (very soft stools/liquid stools) as shown in the BSFS over the 7 most recent days out of the 10 days before colonoscopy preparation (may or may not be contiguous) c. Presence of ulcerations that are characteristic to CD, as determined by a colonoscopy performed during screening, and as defined by the SES-CD \>6 (SES CD \>=4 for isolated ileitis) Note that the participant must be confirmed as meeting the CDAI score and PRO subscore requirements before a colonoscopy is done

Participants must have a documented diagnosis (endoscopic with histology) of CD for \>=3 months before screening. Documented diagnosis is defined as:

1. A biopsy report in which the description of the histological findings is consistent with the CD diagnosis AND

2. A report documenting disease duration based upon prior colonoscopy Note: If a biopsy report is not available in the source document at the time of screening, a biopsy must be performed during the screening colonoscopy and the histology report should be consistent with the CD diagnosis. If the histology description does not support the CD diagnosis at this time point, the participant should not be randomized

Participants must have had an inadequate response to, or lost response to, or had an intolerance to at least 1 conventional treatment such as sulfasalazine or mesalamine (5-aminosalicylic acid \[5-ASA\]), glucocorticoids, or immunosuppressants (azathioprine \[AZA\], 6-mercaptopurine \[6-MP\] or methotrexate \[MTX\]) or anti-tumor necrosis factor (anti-TNF). Participants who have had an inadequate response to sulfasalazine or mesalamine should have also failed at least 1 other conventional treatment such as glucocorticoids

Participants receiving any treatment(s) for CD are eligible provided they have been, and are anticipated to be, on a stable dose for the designated period of time

Participants are males or nonpregnant, nonlactating females who, if sexually active, agree to comply with the contraceptive requirements of the protocol, or females of nonchildbearing potential. Males and females of reproductive potential who are sexually active must agree to use appropriate contraception (ie, highly effective methods for female and medically appropriate methods for male study participants, for the duration of the study

Participants with past medical history or presence of toxic megacolon

Participants with presence of enterovesical (ie, between the bowel and urinary bladder) or enterovaginal fistulae

Participants with current symptomatic diverticulitis or diverticulosis

Participants with clinically significant obstructive colonic stricture, or who have a history of bowel surgery within 6 months before screening, or who are likely to require surgery for CD during the treatment period. Participants who have undergone previous colonic resection or ileocolectomy more than 6 months before screening must have at least 25 cm of colon remaining

Participants with past medical history of multiple small bowel resections resulting in clinically significant short bowel syndrome

Participants requiring total parenteral nutrition

Participants with past medical history of bowel surgery resulting in an existing or current stoma. Participants who had a j-pouch are excluded as a j-pouch could result in a stoma

Participants have had prior treatment with ontamalimab (formerly PF-00547659; SHP647)

Participants with known or suspected intolerance or hypersensitivity to the investigational product(s), closely related compounds, or any of the stated ingredients

Participants have received any nonbiologic treatment with immunomodulatory properties (other than AZA, 6-MP, or MTX) or continuous antibiotics (\>2 weeks) for the treatment of CD within 30 days before baseline (Visit 2)

Participants have received anti-TNF treatment within 60 days before baseline (Visit 2)

Participants have received any biologic with immunomodulatory properties (other than anti-TNFs) within 90 days before baseline (Visit 2)

Participants have ever received anti-integrin/adhesion molecule treatment (eg, natalizumab,vedolizumab, efalizumab, etrolizumab, or any other investigational anti-integrin/adhesion molecule)

Participants have received lymphocytes apheresis or selective monocyte granulocytes apheresis within 60 days before baseline (Visit 2)

Participants have received enteral nutrition treatment within 30 days before baseline (Visit 2)

Participants have received parenteral or rectal glucocorticoids or rectal 5-ASA within 14 days before screening colonoscopy

Participants have taken \>20 milligram per day(mg/day) of prednisone, \>9 mg/day of budesonide, or equivalent oral systemic corticosteroid dose within 14 days before baseline (Visit 2) or have taken \>=40 mg/day of prednisone or equivalent oral systemic corticosteroid dose within 6 weeks before baseline (Visit 2)

Participants have participated in other investigational studies within either 30 days or 5 half-lives of investigational product used in the study (whichever is longer) before screening (Visit 1)

Participants have received a live (attenuated) vaccine within 30 days before the baseline visit (Visit 2)

Participants with active enteric infections (positive stool culture and sensitivity), Clostridium difficile infection or pseudomembranous colitis (subjects with C. difficile infection at screening may be allowed retest after treatment), evidence of active cytomegalovirus infection or Listeria monocytogenes, known active invasive fungal infections such as histoplasmosis or parasitic infections, clinically significant underlying disease that could predispose the subjects to infections, or a history of serious infection (requiring parenteral antibiotic and/or hospitalization) within 4 weeks before the baseline visit (Visit 2)

Participants with abnormal chest x-ray or other imaging findings at screening (Visit 1), such as presence of active tuberculosis (TB), general infections, heart failure, or malignancy (A chest x-ray, computed tomography scan, etc, performed up to 12 weeks before study entry \[screening, Visit 1\] may be used if available; documentation of the official reading must be located and available in the source documentation)

Participants with evidence of active or latent infection with Mycobacterium tuberculosis (TB) or participants with this history who have not completed a generally accepted full course of treatment before baseline (Visit 2) are excluded All other participants must have either the Mantoux (purified protein derivative \[PPD\]) tuberculin skin test or interferon-gamma release assay (IGRA) performed

Participants who have no history of previously diagnosed active or latent TB are excluded if they have a positive Mantoux (PPD) tuberculin skin test (ie \>= 5 millimeter \[mm\] induration) or a positive IGRA (the latter to be tested at the site's local laboratory) during screening or within 12 weeks before screening If the IGRA cannot be performed locally, a central laboratory may be used, with prior agreement from the sponsor:

1. An IGRA is strongly recommended for participants with a prior Bacillus Calmette-Guérin vaccination but may be used for any participant Documentation of IGRA product used and the test result must be in the participant's source documentation if performed locally Acceptable IGRA products include QuantiFERON-TB Gold Plus In-Tube Test

2. If the results of the IGRA are indeterminate, the test may be repeated, and if a negative result is obtained, enrollment may proceed In participants with no history of treated active or latent TB, a positive test on repeat will exclude the participantParticipants with a history of active or latent TB infection must follow instructions for "Participants with a prior diagnosis of active or latent TB are excluded unless both of the following criteria are met" in this criterion

3. Participants with repeat indeterminate IGRA results, with no prior TB history, may be enrolled after consultation with a pulmonary or infectious disease specialist who determines low risk of infection (ie, participant would be acceptable for immunosuppressant \[eg, anti-TNF\] treatment without additional action) This consultation must be included in source documentation Results from a chest x-ray, taken within the 12 weeks before or during screening (Visit 1)must show no abnormalities suggestive of active TB infection as determined by a qualified medical specialist

Participants with a pre-existing demyelinating disorder such as multiple sclerosis or new onset seizures, unexplained sensory motor, or cognitive behavioral, neurological deficits, or significant abnormalities noted during screening

Participants with any unexplained symptoms suggestive of PML based on the targeted neurological assessment during the screening period

Participants with a transplanted organ. Skin grafts to treat pyoderma gangrenosum are allowed

Participants with a significant concurrent medical condition at the time of screening (Visit 1) or baseline (Visit 2), including, but not limited to, the following:

1. Any major illness/condition or evidence of an unstable clinical condition (eg, renal, hepatic, hematologic, GI \[except disease under study\], endocrine, cardiovascular, pulmonary, immunologic \[eg, Felty's syndrome\], or local active infection/infectious illness) that, in the investigator's judgment will substantially increase the risk to the subject if he or she participates in the study

2. Cancer or history of cancer or lymphoproliferative disease within the previous 5 years (other than resected cutaneous basal cell carcinoma, squamous cell carcinoma, or carcinoma in situ of the uterine cervix that has been treated with no evidence of recurrence)

3. Presence of acute coronary syndrome (eg, acute myocardial infarction, unstable angina pectoris) within 24 weeks before screening (Visit 1)

4. History of significant cerebrovascular disease within 24 weeks before screening (Visit 1)

Participants who have had significant trauma or major surgery within 4 weeks before the screening (Visit 1), or with any major elective surgery scheduled to occur during the study.

Participant with evidence of cirrhosis with or without decompensation (ie, esophageal varices, hepatic encephalopathy, portal hypertension, ascites)

Participant with primary sclerosing cholangitis

Participant with chronic hepatitis C virus (HCV) (positive HCV antibody \[HCVAb\] and HCV RNA) Note: Participant who are HCVAb positive without evidence of HCV RNA may be considered eligible (spontaneous viral clearance or previously treated and cured \[defined as no evidence of HCV RNA at least 12 weeks prior to baseline\])

Participant with any of the following abnormalities in hematology and/or serum chemistry profiles during screening (Visit 1) Note: Screening laboratory tests, if the results are considered by the investigator to be transient and inconsistent with the subject's clinical condition, may be repeated once during the screening period for confirmation results must be reviewed for eligibility prior to the screening colonoscopy procedure

1. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels \>=3.0 × the upper limit of normal (ULN)

2. Total bilirubin level \>=1.5 × ULN or \>2.0 × ULN if the subject has a known documented history of Gilbert's syndrome

3. Hemoglobin level less than or equal to(\<=80) gram per liter(g/L) (8.0 g/deciliter\[dL\])

4. Platelet count \<=100× 10\^9/L (100,000 cells/mm\^3) or \>=1000 × 10\^9/L (1,000,000 cells/mm\^3)\*

5. White blood cell count \<=3.5 × 10\^9/L (3500 cells/mm\^3)

6. Absolute neutrophil count \<2 × 10\^9/L (2000 cells/mm\^3)

7. Serum creatinine level \>1.5 × ULN or estimated glomerular filtration rate \<30 millilter per minute (mL/min)/173 meter square (m\^2) based on the abbreviated Modification of Diet in RenalDisease Study Equation Note: if platelet count is \<150,000 cells/mm3, a further evaluation should be performed to rule out cirrhosis, unless another etiology has already been identified

Participant with known human immunodeficiency virus (HIV) infection based on documented history with positive serological test, or positive HIV serologic test at screening, tested at the site's local laboratory in accordance with country requirements or tested at the central laboratory Note: A documented negative HIV test within 6 months of screening is acceptable and does not need to be repeated

With known human immunodeficiency virus (HIV) infection based on documented history with positive serological test, or positive HIV serologic test at screening, tested at the site's local laboratory in accordance with country requirements or tested at the central laboratory.

Participants who have, or who have a history of (within 2 years before screening), serious psychiatric disease, alcohol dependency, or substance/drug abuse or dependency of any kind including abuse of medicinal marijuana (cannabis)

What this study is about