The Efficacy of Fecal Microbiota Transplatation on Axial Spondyloarthritis Patients Resistant to Conventional Treatment

Inclusion Criteria: * Adult patient (age 18 to 75 years old) with SpA, meeting the ASAS classification criteria for axial SpA, with presence of radiographic sacro-illitis (ankylosing spondylitis) or not. * Patient suffering of active SpA, with or without treatment, having a BASDAI score ≥ 4 (0-10) at baseline and a score of back pain ≥ 4 (0-10) despite optimal drug management for at least 6 months including at least 2 different NSAIDs at the maximum tolerated dose for at least 2 months (or less in case of intolerance or contra-indication) and at least a first line of biotherapy (anti-TNFα or anti-IL-17) for at least 4 months (or less in case of intolerance or contra-indication). * Subjects are allowed to continue NSAID, sulfasalazin (≤ 3 g/day) and/or methotrextae ( ≤ 25 mg/week) and/or hydroxychloroquine (≤ 400 mg/day) and/or oral corticosteroid (≤ 10 mg/day of prednisone), as long as these treatments have remained at stable dose for 4 weeks prior to baseline. * Subjects are allowed to continue anti-TNFα, anti-IL-17 or JAKinhibitor therapies, as long as these treatments have remained at stable dose for 3 months prior to baseline. * Women of childbearing potential with efficient contraceptive protection at the inclusion and during at least the interventional phase (D168). * Patient with health insurance (AME except). * Patient is willing to provide written informed consent prior to enrolment and agrees to follow the protocol. Exclusion Criteria: 1. Patient under legal protection (guardianship or curatorship) 2. Subject who, in the judgment of the Investigator, is likely to be non-compliant or uncooperative during the study, or unable to cooperate because of a language problem, poor mental development 3. Pregnant or breastfeeding woman 4. Patient with IBD in active state, according to the judgment of the Investigator 5. Corticosteroid injection within 4 weeks before inclusion 6. Active infection according to the judgment of the Investigator 7. Any antibiotic (including Sulfasalazin) or antifungal treatment within 4 weeks before inclusion 8. Probiotics intake within 4 weeks before inclusion 9. Known infection with Clostridoides difficile or Escherichia coli within 10 days before inclusion 10. Patients with unstable severe condition other than axial SpA on that could jeopardize treatment procedure or evaluation according to the investigator's assessment 11. Previous FMT treatment 12. Contra-indication to colon preparation (Moviprep® or Moviprep orange®) according to SmPC 13. Current or past evidence of bowel obstruction 14. Confirmed or suspected intestinal ischemia 15. Confirmed or suspected toxic megacolon or gastrointestinal perforation 16. Extended colectomy (\> two-thirds of colon) 17. Any gastro-intestinal bleeding in the past 3 months before inclusion 18. Any history of gastro-intestinal surgery in the past 3 months before inclusion 19. Severe organ dysfunction 20. Any contra-indication to swallow capsules 21. Known allergy or intolerance to IMP and / or excipients according to Investigator's Brochure 22. Lack of access to a refrigerator to store the medication (MaaT033® or MaaT030®) 23. Concomitant participation in another interventional clinical trial