Study Evaluating AZD7798 for Treatment in Crohn's Disease Patients With an Ileostomy

Inclusion Criteria:

• 18 to 80 years of age.

• Diagnosis of Crohn's disease established with clinical, imaging, endoscopic, and/orhistopathologic evidence.

• Ileostomy for at least 3 months.

• Prior to screening endoscopy, clinical suspicion of active ileal inflammation basedon at least one of the following: previous endoscopy, imaging (CT, MRI, IUS), or FCPabove upper reference limit.

• Active ileal Crohn's disease as determined by active intestinal mucosalinflammation, as demonstrated on video recorded ileoscopy performed during thescreening period and scored by a blinded central reader with agreement on the SES CD ≥ 4 of the ileal segment proximal to the stoma. Participants with inflammation inadditional intestinal segments are not excluded.

• Capable of giving signed informed consent.

Exclusion Criteria:

• Concomitant additional gastrointestinal luminal inflammatory diseases

• Strictures/stenoses preventing passage of endoscope throughout the specified segment

• Short bowel syndrome

• Within 3 months prior to screening:

1. Diagnosis of peritonitis or need treatment of peritonitis

2. Bowel perforation or evidence of obstruction

• All intrabdominal, cutaneous and perianal/perirectal abscesses and fistulae areexcluded with exception of: cutaneous and perianal/perirectal abscesses which areadequately drained 4 weeks prior to randomization, and intraabdominal fistulaebetween bowel segments only without complications

• Ongoing or expected nutritional dependency on total enteral or parenteral nutritionduring study (partial nutrition acceptable).

• In participants with any remaining colon and/or rectum, evidence of an increasedrisk of colorectal cancer, including:

1. Adenomatous colonic/rectal polyps that have not been removed

2. Intestinal dysplasia

3. Not undertaking appropriate surveillance, if indicated, for colorectaldysplasia/malignancy

• Reversal of ileostomy or formation of J-pouch planned prior to end of study period.

• High-output stoma (eg, > 2000 mL/24 hours) associated with volume depletion and/orelectrolyte disturbance to the extent that, in the opinion of the Investigator, itmay put the participant at undue risk because of participation in the study, orimpact their ability to participate in the study or interfere with theinterpretation of study data.

• Any of the following treatments within the specified time period:

1. An anti-TNF biologic within 8 weeks prior to randomization

2. Any biologic targeting immune response other than an anti-TNF (includingvedolizumab and ustekinumab) within 12 weeks prior to randomization.

3. Other advanced small molecule treatments for Crohn's disease within 4 weeksprior to randomization

4. Cyclosporine, mycophenolate mofetil, sirolimus (rapamycin), thalidomide, ortacrolimus within 4 weeks prior to randomization

5. Treatment with apheresis (eg, Adacolumn, Cellsorba) within 4 weeks prior torandomization

6. Administration of any live vaccine within 4 weeks prior to randomization, orplanned administration of any such vaccine during the study

7. Faecal microbiota transplantation within 4 weeks prior to randomization

8. Regular intake of NSAIDs within 12 weeks prior to screening ileoscopy andduring the study (defined as at least times per week for more than 3 months;not applicable to daily aspirin use up to 325 mg per day)

9. Lymphocyte-depleting treatment, including, but not limited to rituximab, within 12 months prior to randomization

• Any changes in dosing of the following medications prior to screening ileoscopy asoutlined

1. 5-aminosalicylates within 2 weeks

2. Oral corticosteroids within 2 weeks. Also excluded if on stable dosing ofsteroids exceeding the following dose equivalents:

(i) Systemic steroids > 20 mg/day prednisolone dose or equivalent (ii) Locallytargeted steroids exceeding maximum budesonide dose or equivalent [9 mg/day] (c)Immunomodulators (thiopurines or methotrexate) within 4 weeks (d) Antibiotic therapyfor the treatment of Crohn's disease, eg, ciprofloxacin or metronidazole within 2weeks (e) Probiotics within 2 weeks

• Evidence of recent or currently active infection, including use of IV or oralantibiotics for documented infection within 30 days prior to screening.

• Evidence of chronic hepatitis B or C infection

• History of TB (active or latent) unless an appropriate course of treatment has beencompleted.

• Positive diagnostic TB test at screening.

• History of serious opportunistic infection within 12 months prior to screening

• Symptomatic herpes zoster infection within 3 months prior to screening.

• Positive C. difficile toxin test at screening.

• Any identified immunodeficiency

• Any other abnormal laboratory results at screening, which, in the opinion of theInvestigator, will prevent the participant from completing the study or willinterfere with the interpretation of the study results

• Prolonged QTcF interval > 450 ms (or > 480 ms for patients with bundle branch block)or congenital long-QT syndrome or family history of long-QT syndrome or suddencardiac death in age < 40 years.

• Clinically significant cardiovascular conditions

• Reproduction:

1. Pregnant and breastfeeding participants, or those planning to breastfeed duringthe study

2. FOCBP, unless they agree to complete abstinence or to use a highly effectivecontraceptive method AND barrier method

• Current malignancy or history of malignancy

• Current significant major or unstable respiratory disease, heart disease,cerebrovascular disease, haematological disease, hepatic disease including largeduct primary sclerosing cholangitis with jaundice, recurrent cholangitis orcirrhosis, renal disease, gastrointestinal disease, or other major disease otherthan active Crohn's disease.

• Current enrolment in another interventional study or treatment with anyinvestigational drug within 4 months (or 5 half-lives, whichever is longer) prior toscreening

• Unstable lifestyle factors

• Participants committed to an institution by virtue of an order issued either by thejudicial or the administrative authorities.

• Involvement in the planning and/or conduct of the study

• Judgement by the Investigator that the participant should not participate in thestudy if the participant is unlikely to comply with study procedures, restrictions,and requirements.

• Previous randomization in the present study.