A Study to Evaluate Biomarkers in Moderate to Severe Ulcerative Colitis (UC) Patients Treated With Different Targeted Therapies

Inclusion Criteria: * Male and female patients ≥ 18 years of age (at the time of signing the ICF) * Established diagnosis of ulcerative colitis with a minimum disease duration of 3 months * Moderate to severe active UC defined by Mayo Score ≥ 6 * Moderate to severe active UC defined by endoscopy score of ≥2 * Indication to start any biological or small molecule agent (anti-TNF, anti- IL12/23, anti-integrin and JAK-inhibitors) * In case of treatment with corticosteroid: stable dose for at least 3 weeks prior to baseline, dosage ≤ 20 mg prednisone * Indication for an endoscopy for the assessment of disease activity as for standards of care and current guidelines * Able to comply with the study procedures * Person affiliated to or beneficiary of a social security plan * Person informed about study organization and able to sign informed consent form Exclusion Criteria: * Diagnosis of indeterminate colitis, microscopic colitis, ischaemic colitis, infectious colitis, radiation colitis * Absolute contraindications to endoscopy procedures or complication during previous endoscopy * Bleeding disorders * Indication for surgery for UC * Rectal topical therapy (enemas or suppositories) ≤ 2 weeks prior to baseline * Treatment with \> 20 mg prednisone within 3 weeks prior to baseline * Anaemia (haemoglobin \< 10 g/dl) at baseline * Any circumstances which could contradict a study participation and lead the Investigator to assess the patient as unsuitable for study participation for any other reason * Person referred in articles L.1121-5, L. 1121-7 and L.1121-8 of the Public Health Code: * Pregnant, parturient or breastfeeding woman * Minor person (non-emancipated) * Adult person under legal protection (any form of public guardianship) * Adult person incapable of giving consent and not under legal protection * Person deprived of liberty for judicial or administrative decision, person under psychiatric care as referred in articles L. 3212-1 and L. 3213-1