Transfer of FRozen Encapsulated Multidonor Stool Filtrate for Active Ulcerative COlitis

Inclusion Criteria:

• Age between 18 and 75 years

• Prior endoscopic confirmation of UC of at least 6 months AND with a minimum diseaseextent of 15 cm from the anal verge.

• Having active disease, defined with a Mayo Score between 4-10 and Mayo endoscopicsubscore >1

• Failure of conventional therapy or treatment with biologicals and / or smallmolecules.

• previous medical therapy:

• oral 5-ASA compounds (5-ASA); stable dosing for 4 weeks before randomization;

• Azathioprine, 6-Mercaptopurine (6-MP) or Methotrexate (MTX); stable dosing for 8 weeks before randomization;

• Oral corticosteroid therapy (prednisone ≤ 20 mg/day or budesonide ≤ 9 mg/day);stable dosing for 2 weeks before randomization;

• Topical therapy (foams, clysms) with mesalazine or budesonide: stable dosingfor 2 weeks before randomization.

• previous vaccination against SARS-CoV-2 or previous SARS-CoV-2 infection or positiveserology

• Ability to understand and willingness to sign informed consent document in patientswhom the investigator believes can and will comply with the requirements of theprotocol.

• Potentially childbearing patient: negative pregnancy test and use of a highlyeffective contraceptive method

Exclusion Criteria:

• Crohn's disease or indeterminate colitis or proctitis ulcerosa alone

• Acute abdomen or other clinical emergencies (e.g. toxic megacolon, fulminantgastrointestinal hemorrhage, ileus, perforation, etc.)

• Previous operations on the colon: colectomy, partial colon resections

• current gastrointestinal infections

• Congenital or acquired immunodeficiency

• severe comorbidity (e.g. insulin-dependent diabetes mellitus, decompensated livercirrhosis, primary sclerosing cholangitis, renal impairment > grade 2)

• diagnosis of a malignoma in the last 3 years

• refusal of endoscopies with video documentation

• No specific therapy for ulcerative colitis to date

• Lack of immunity to SARS-CoV-2

• Previous treatment with TNF-, IL12/IL23-, IL23- or integrin-antibodies within thelast 8 weeks before randomisation

• Treatment with calcineurin inhibitors within the last 4 weeks before randomization

• Treatment with JAK inhibitors (e.g., tofacitinib, filgotinib, or upadacitinib)within the last 4 weeks prior to randomization

• Treatment with S1P receptor modulators (e.g. ozanimod, etrasimod) within the last 4weeks before randomization

• Systemic antibiotic treatment within the last 8 weeks prior to randomization.

• Known intolerance of metronidazole or vancomycin

• Previous FMT or FMFT, previous participation in this study (screening allowed)

• Participation in a clinical trial within the last 3 months

• Use of probiotics in tablet, capsule, or powder form, or appropriate drinkingyogurts (or similar) within 2 weeks prior to randomization

• Failure to ensure frozen storage of investigational products

• Addictive or other medical conditions or circumstances that do not allow the subjectto appreciate the nature, significance, scope, and possible consequences of theclinical trial

• Indications that the patient would be unlikely to comply with the protocol (e.g.,unwillingness to cooperate - compliance questionable)