Ulcerative colitis (UC) represents one of the major entities of idiopathic inflammatory bowel diseases which are defined as chronically relapsing inflammations of the gastrointestinal tract not due to specific pathogens. It is characterised by a superficial, continuous mucosal inflammation, which predominantly affects the large intestine. The clinical course is typically marked by periods of asymptomatic remission punctuated by unpredictable recurrent attacks. The symptoms of the patients are marked by persistent diarrhoea with severe faecal urgency and often incontinence, rectal bleeding, abdominal cramping and weight loss.

Uncontrolled activation of mucosal effector T cells has been identified as the main pathogenic mechanism involved in the initiation and perpetuation of intestinal inflammatory reactions.

Patients with moderate UC are initially treated with mesalazine, applied both orally and rectally. If symptoms do not improve, systemic corticosteroids are to be administered. Patients who do not respond to systemic corticosteroids may become eligible for treatment with a calcineurin inhibitor or an anti-tumor necrosis factor (TNF)α antibody. Alternatively, patients may have to undergo major colorectal surgery.

Patients who do not adequately respond to these treatment strategies exhibit serious drawbacks. Colorectal surgery may result in a severely compromised quality of life.

Therefore, patients with moderate or severe UC may significantly benefit from new therapeutic alternatives.

The transcription factor GATA-3 is an interesting target for a novel therapeutic strategy in UC.

GATA-3 is the key regulation factor of Th2-driven immune responses. It is indispensable for the differentiation and activation of Th2 cells, integrates Th2 signals, and induces Th2 cytokine expression. Results of a recent clinical trial in children showed that GATA-3 is involved in the pathogenesis of the acute phase of UC.

The investigational product SB012 contains the DNAzyme hgd40 that targets GATA-3. By cleaving GATA-3 mRNA hgd40 reduces specific cytokine production and thereby reduces key features of mucosal inflammation.

DNAzymes are completely generated by chemical synthesis, not by use of any living organism and are therefore not biological drugs.

This study will evaluate the efficacy, safety, tolerability and pharmacokinetics of the topical formulation SB012 available in a concentration of 7.5mg/ml hgd40 in 30ml PBS once daily as a ready-for-use enema in patients with active UC.

Inclusion Criteria:

The trial population consists of adult subjects of both sexes with active ulcerative colitis aged 18 to 75 years.

The main inclusion criteria comprise:

• Fully capable to give informed consent.
• Mentally able to understand the nature, significance, implications and risks of the clinical trial and to follow instructions of the trial staff.
• Written informed consent
• Clinical Mayo Score of ≥3
• Total Mayo Score of ≥6
• Endoscopic Mayo score ≥2 in the sigmoid
• Body mass index ≥18.0 to ≤29.0kg/m2 and body weight ≥50 to ≤100kg
• Negative urine pregnancy test (female subject only)
• Using two methods of contraception

Exclusion Criteria:

• Colectomy and presence of ileal pouch-anal anastomosis or ileorectal anastomosis
• Diagnosis of ulcerative proctitis, fulminant colitis, toxic megacolon, of colitis indeterminata or Crohn's disease
• Ileostoma
• Anti-TNFα treatment with adalimumab, certolizumab, etanercept, golimumab, or infliximab ≤4 weeks prior to screening visit.
• Change in systemic glucocorticoid treatment ≤1 weeks prior to screening visit
• Change in 5-Aminosalicylic Acid (ASA) therapy ≤1 week prior to screening visit
• Start of treatment with an immunosuppressive agent ≤3 months prior to screening visit
• Change in treatment with an immunosuppressive agent ≤4 weeks prior to baseline visit
• Planned concomitant therapeutic administration of suppositories or foams or enema other than the IMP.
• Impaired blood coagulation (Quick value <50% and/or partial thromboplastin time (PTT) >55sec and/or platelet count <50.000/μl.)
• Signs of renal insufficiency
• Signs of hepatic insufficiency.
• Current treatment with drugs of high hepatotoxic potential.
• Evidence of recent alcohol abuse.
• Acute or chronic heart failure with NYHA functional class III or IV.
• Known active tuberculosis.
• Known acute serious infections or sepsis.
• Known current malignant disease.
• Positive blood test against HBs antigen, anti-HBc antibodies, anti-HCV antibodies or anti-HIV-1/2 antibodies.
• Known opportunistic infections including invasive fungal infections.
• Known hypersensitivity to the IMP or any of their formulation ingredients.
• Any condition that is thought to reduce the compliance to cooperate with the trial procedures.
• Employee of the department of the investigator, of the Center for Clinical Studies (CCS) or of the sponsor.
• Prior participation in this clinical trial.
• Participation in an interventional clinical trial within the last three months (six months in case of a biological IMP) or be under the exclusion period from another clinical trial.
• Known or planned absence that may collide with the clinical trial visit schedule.