Phase 3 Study of Cx601 in Participants With Complex Perianal Fistulising Crohn's Disease

The purpose of this study is to evaluate the efficacy of darvadstrocel for the treatment of complex perianal fistulas in adult participants with Crohn's disease over 24 weeks.

The drug being tested in this study is called Darvadstrocel (Cx601). This study will assess the efficacy for 24 and 52 weeks, and safety for 156 weeks of darvadstrocel when administered with intralesional injection in adult participants with Crohn's disease whose complex perianal fistulas were previously treated and refractory.

The study enrolled 22 participants. All participants who will meet the criteria will be assigned to screening period for approximately 5 weeks and after that will be enrolled the treatment period which will be the day of study product administration. After the treatment period, this study will include the follow-up period for approximately 52 weeks after study product administration, and the long-term follow-up period from Week 52 to Week 156.

This multi-center trial will be conducted in Japan. The overall time to participate is totally approximately 156 weeks (3 years) from the start of treatment period plus follow-up and long-term follow-up period. Participants will make multiple visits to the clinic and a final visit 156 weeks after treatment of study product for a follow-up assessment.

Eligibility Criteria:
Inclusion Criteria:

1. In the opinion of the investigator, the participant is capable of understanding and complying with the protocol requirements.
2. The participant or, when applicable, the participant's legally acceptable representative signs and dates a written, informed consent form and any required privacy authorization prior to the initiation of any study procedures.
3. The participant who was diagnosed with Crohn's disease at least 6 months prior to the screening period according to the Diagnostic Criteria for Crohn's Disease issued by Research Group for Intractable Inflammatory Bowel Disease Designated as Specified Disease by the Ministry of Health, Labour and Welfare (MHLW) of Japan (revised January 2017).
4. The participant is either a male or female outpatient, aged 18 years or older at the time of signing the informed consent form.
5. The participant who has non-active or mildly active Crohn's disease defined by the Crohn's disease activity index (CDAI) =\<220 evaluated at any time between Visit 1 and Visit 2.
6. The participant who has complex perianal fistulas with a maximum of 2 internal openings and a maximum of 3 external openings, confirmed by clinical assessment and MRI. All of the external openings must connect to internal openings. Fistula must have been draining for at least 6 weeks prior to the screening. Complex perianal fistula is defined as the one that meets 1 or more of the following criteria:

   * High (ie, above the dentate line) inter-sphincteric or trans-sphincteric fistula, extrasphincteric fistula, or supra-sphincteric fistula.
   * Presence of \>=2 external openings (tracts).
   * Associated fluid collections.
7. The participant whose perianal fistulas were previously treated and have shown an inadequate response (absence of closure of part or all fistula tract, or new fistula during induction treatment) or a loss of response (fistula relapse after complete closure of initial fistula, or fistula worsening after partial closure of initial fistula during maintenance treatment) while they were receiving either immunosuppressants or biologics, or having documented intolerance (occurrence, at any time, of an unacceptable level of treatment-related side effects that makes necessary treatment discontinuation) to any of these treatments administered at least approved or recommended doses during the minimum period mentioned;

   * Antibiotics (ciprofloxacin or metronidazole): 1 or more month treatment.
   * Immunosuppressants (azathioprine, 6-mercaptopurine or methotrexate): 3 or more months treatment.
   * Biologics (anti-tumor necrosis factors \[TNFs\], anti-integrin or anti-interleukin \[IL\]-12/23): 14 or more weeks (16 or more weeks for anti-IL-12/23) standard treatment for induction or maintenance.
8. A male participant who is nonsterilized and sexually active with a female partner of childbearing potential agrees to use adequate contraception from signing of informed consent up to Week 52 of the study.
9. A female participant of childbearing potential who is sexually active with a nonsterilized male partner agrees to use routinely adequate contraception from signing of informed consent up to Week 52 of the study.

Exclusion Criteria:

1. The participant whose CDAI is \>220 at any time between Visit 1 and Visit 2, or who has active Crohn's disease requiring a new of escalating immediate therapy.
2. The participant who has concomitant rectovaginal or rectovesical fistulas.
3. The participant who has \>2 internal openings of \>3 external openings.
4. The participant who is naïve to protocol required treatment for complex perianal fistulising Crohn's disease (ie, antibiotics, immunosuppressants or biologics).
5. The participant who has an abscess or collections \>2 cm.
6. The participant who has rectal and/or anal stenosis and/or active proctitis, which would restrict the surgical procedure.
7. The participant who underwent surgery other than drainage or seton placement for the to be treated fistula.
8. The participant who has diverting stomas.
9. The participant who was treated with systemic steroids in the 4 weeks prior to study product administration.
10. The participant receiving cytapheresis therapy.
11. The participant who requires new treatment with immunosuppressants/biologics/non-tapered systematic steroids during the screening period.
12. The participant who has renal impairment defined by creatinine clearance below 60 mL/minute calculated using Cockcroft-Gault formula or by serum creatinine \>=1.5 × upper limit of normal (ULN).
13. The participant who has hepatic impairment defined by both total bilirubin \>=1.5 × ULN, and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) \>=2.5 × ULN.
14. The participant who has history of abuse of alcohol or other addictive substances in the 6 months prior to the screening period.
15. The participant who has malignant tumour or who has a history of malignant tumour, including any type of fistula carcinoma.
16. The participant who has abnormal, severe, progressive, uncontrolled hepatic, hematological, gastrointestinal (except Crohn's disease), endocrine, pulmonary, cardiac, neurological, psychiatric, or cerebral disease, or the participant who developed any of the above diseases within 3 months prior to the screening period.
17. The participant who has congenital or acquired immunodeficiency, including participants known to be Human Immunodeficiency Virus (HIV) carriers.
18. The participant who has clinically significant chronically active hepatopathy of any origin, including hepatic cirrhosis, and participants who is persistent positive for hepatitis B virus (HBV) surface antigen (HBsAg) and quantitative HBV polymerase chain reaction (PCR), or positive serology for hepatitis C virus (HCV) and quantitative HCV-PCR within 6 months prior to the screening period.
19. The participant who has known allergies or hypersensitivity to antibiotics (including but not limited to penicillin, streptomycin, gentamicin, aminoglycosides), Human Serum Albumin (HSA), bovine-derived materials, local anesthetics or gadolinium (MRI contrast agent).
20. The participant for whom MRI scan is contraindicated (eg, due to the presence of a pacemaker, a history of hip replacements, or severe claustrophobia).
21. The participant who has major surgery (eg, surgery under general anesthesia, laparotomy, thoracotomy, craniotomy) or severe trauma within 6 months prior to the screening period.
22. The female participant who is pregnant, or is lactating.
23. The participant who has received any investigational drug within 12 weeks (84 days) prior to the screening.
24. The participant who has received expanded allogeneic adipose-derived stem cells (eASC) in a previous clinical study or as a therapeutic agent.
25. The participant who needs perianal surgery other than fistulas preparation required by the protocol during the screening, or the participant who will receive a perianal surgery within 24 weeks after study product administration.
26. The participant for whom anesthesia is contraindicated.
27. The participant who received excluded medications or treatment.