A Study of Darvadstrocel for Treating Complex Perianal Fistulas in Children and Teenagers With Crohn's Disease

Inclusion Criteria:

1. Has a CD diagnosis based on accepted clinical, endoscopic, histological and/orradiologic criteria at least 6 months before the screening visit.

2. Has complex perianal fistula refractory to at least one of the following treatments:immunosuppressants or biologics (anti-TNFs, anti-integrin, anti-interleukin [IL] 12/23). Fistula(s) refractory to therapy is defined in this study as follows:Immunosuppressants: Inadequate response after 3 months, based on clinicalassessment, or more treatment with azathioprine, 6-mercaptopurine or methotrexate.Biologics: Inadequate response after 14 weeks (16 weeks for anti-IL 12/23), based onclinical assessment, or more standard treatment for induction and maintenance.

3. A complex perianal fistula(s) that meets one or more of the following criteria,modified from the American Gastroenterological Association (AGA) technical review:High intersphincteric, transsphincteric, extrasphincteric, or suprasphincteric asassessed by MRI. Presence of 2 or 3 external openings (tracts) as assessed byclinical examination. Associated fluid (abscess) collections as determined by MRI. This study requires that the participant has complex perianal fistulas with amaximum of 2 internal openings and a maximum of 3 external openings, based onclinical assessment. Darvadstrocel treatment is targeted for fistulas that connectbetween internal and external openings. A central reading of a locally performedpelvic MRI will be performed to confirm the location of the fistula and potentialassociated perianal abscess(es). Fistulas must have been draining for at least 6weeks before the screening visit. Participants with actively draining simplesubcutaneous fistulas, at the time of the screening visit, are not allowed in thisstudy.

4. Has inactive or mildly active luminal CD defined by meeting all of the followingcriteria:

5. Colonoscopy, flexible sigmoidoscopy or rectoscopy performed either at screeningor within the 6 months before screening, demonstrating no rectal ulcers largerthan 0.5 cm. A participant who has documented rectal ulcers larger than 0.5 cmwithin the 6 months before screening but has undergone subsequent treatment maybe eligible if there are no rectal ulcers larger than 0.5 cm on a sigmoidoscopyor rectoscopy performed after treatment or at the time of screening.

6. The improvement of, or no worsening in stool frequency, sustained for 1 week ormore, in the interval between the colonoscopy, flexible sigmoidoscopy orrectoscopy in inclusion criteria 4(a) and the screening visit.

7. No initiation or intensification of treatment with corticosteroids,immunosuppressants, or monoclonal antibody dose regimen between thecolonoscopy, flexible sigmoidoscopy or rectoscopy in inclusion criteria 4(a)and the screening visit.

Exclusion Criteria:

1. Has received any investigational compound within 12 weeks/84 days before screening.

2. Has received darvadstrocel/eASC in a previous clinical study or as a therapeuticagent.

3. The participant weighs <10 kg at screening.

4. Has concomitant perianal fistula(s) with only internal or external opening(s).

5. Has concomitant internal fistula(s) such as ileo-vesical, rectovaginal orileo-colonic fistula(s).

6. Has an abscess >2 cm, unless resolved in the preparation procedure.

7. Has rectal and/or anal stenosis, and/or active proctitis, which would restrict thesurgical procedure.

8. The participant underwent surgery for the fistula other than drainage or setonplacement.

9. Has diverting stomas.

10. Has ongoing systemic corticosteroid treatment or has been treated with systemiccorticosteroids within 4 weeks before screening.

11. The participant requires new treatment with immunosuppressants/anti-TNF agentsduring the screening period.

12. The participant has known or suspected COVID-19 by the investigator within the past 2 months (additional testing may be performed at the discretion of theinvestigator). Positive antibody testing for COVID without other evidence of currentor recent active infection does not exclude participation. Participants who were inscreening at the time that COVID-19-related factors resulted in discontinuation mayalso be rescreened with approval of the sponsor or designee.

13. The participant requires surgery in the perianal region for reasons other thanfistulas at the time of screening or foreseen either during the study and/or duringthe 24 weeks after treatment administration.

14. Has malignant tumor or a prior history of any malignant tumor, including any type offistula carcinoma.

15. Has current or recent (within 3 months before the screening) history of abnormal,severe, progressive, uncontrolled hepatic, hematologic, gastrointestinal (exceptCD), endocrine, pulmonary, cardiac, neurological, psychiatric, or cerebral disease.

16. Has either congenital or acquired immunodeficiencies, including participants knownto be HIV carriers or participants with, in the judgment of the investigator, aresuspected to have monogenic inflammatory bowel disease.

17. Has previously received a bone marrow transplant.

18. Has a contraindication to MRI scan or other planned study procedures.

19. Has a contraindication to the anesthetic procedure.

20. Had major surgery or severe trauma within 6 months before the screening visit.