Dose-Evaluation Study of the Efficacy and Safety of TLA Gut™ Leukapheresis Treatment in Patients With Ulcerative Colitis

Inclusion Criteria: Female or male patients 18 to 80 years of age * Active UC without Ileorectal anastomosis (IRA) * Active UC is defined as: * Total Mayo score of ≥ 6 to 11 points * Flexible rectosigmoidoscopy findings of 2 or 3 (0 inactive disease, 1; mild disease, 2; moderate disease or 3; severe disease) * Minimum extension of inflammation 10 cm from anus. * Active disease with no medical treatment OR Active disease despite receiving concomitant therapy with one or more of the following agents: * ≤20 mg prednisolone daily. Stable dose ≥1 week prior to the start of the investigation. * 5-Aminosalicylate (5-ASA) agents for ≥4 weeks and stable dose for ≥2 weeks (local or systemic administration) * Rectal administration of corticosteroids in a stable dose for ≥2 weeks * Azathioprine or 6-mercaptopurine for ≥8 weeks or stable dose ≥2 weeks * No anti-tumour necrosis factor (TNF) treatment (Adalimumab, Infliximab, Golimumab, Certolizumab), anti-integrin-treatment (vedolizumab), Interleukin (IL)-12/23 inhibitor (Ustekinumab) or Janus Kinase (JAK) treatment (Tofacitinib) during the last 4 weeks prior to entering the study * Patients with peripheral veins suitable for extracorporeal treatment - must be examined by the treating apheresis specialist * Willing and able to give written informed consent Exclusion Criteria: Involvement in any investigational drug or device trial within 30 days prior to this investigation * Patients with peripheral veins not suitable for extracorporeal treatment * Fever, defined as a temperature of \>38,5 Celsius degrees (ºC), at the Screening Visit * Heart failure * Coronary artery disease * Cardiomyopathy * Valvular heart disease * Cardiac arrythmia class IV * Underweight person (BMI \< 19) * Hypotension (\< 90/55 mmHG) * Hypoproteinemia * Evidence of toxic megacolon * History of hypersensitivity to heparin * Heparin-induced thrombocytopenia * History of cerebrovascular incident * Known clinically significant bleeding disorder * Colectomy planned within 6 months * Concomitant anticoagulant therapy * History of hypercoagulable disorders * Severe anaemia or Leukopenia * Patients with active viral hepatitis and/or human immunodeficiency virus (HIV) infections * A positive urine pregnancy test at the screening visit * Patients that are nursing Local intestinal treatments with suppositories, enemas, creams, ointments or foams during the last 2 weeks * Current daily smoking habits * Patients unwilling to meet the requirements of the clinical investigational plan * Other medical or social reasons for exclusion at the discretion of the investigator