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

Inclusion Criteria

• In the opinion of the investigator, the participant is capable of understanding and complying with the protocol requirements.
• 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.
• 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).
• The participant is either a male or female outpatient, aged 18 years or older at the time of signing the informed consent form.
• The participant who has non-active or mildly active Crohn's disease defined by the Crohn's disease activity index (CDAI) = =2 external openings (tracts).
• Associated fluid collections.
• 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.
• 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.
• 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

• 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.
• The participant who has concomitant rectovaginal or rectovesical fistulas.
• The participant who has >2 internal openings of >3 external openings.
• The participant who is naïve to protocol required treatment for complex perianal fistulising Crohn's disease (ie, antibiotics, immunosuppressants or biologics).
• The participant who has an abscess or collections >2 cm.
• The participant who has rectal and/or anal stenosis and/or active proctitis, which would restrict the surgical procedure.
• The participant who underwent surgery other than drainage or seton placement for the to be treated fistula.
• The participant who has diverting stomas.
• The participant who was treated with systemic steroids in the 4 weeks prior to study product administration.
• The participant receiving cytapheresis therapy.
• The participant who requires new treatment with immunosuppressants/biologics/non-tapered systematic steroids during the screening period.
• 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).
• The participant who has hepatic impairment defined by both total bilirubin >=1.5 × ULN,