P049 A new preclinical rationale for first-line therapy of ulcerative colitis

H. Thorlacius1, A. Bjoerk2, Ö. Nordle2, G. Hedlund2

1Department of Clinical Sciences, Section of Surgery Skåne University Hospital Lund University, Malmö, Sweden, 2Pharmacyl AB, Preclinical Research, Bjärred, Sweden


Ulcerative colitis (UC) is a chronic inflammatory condition with no known medical cure. 5-Aminosalicylic acid (5-ASA [mesalazine]) represents the cornerstone of first-line therapy for mild-to-moderate UC. Sulfasalazine (SASP) is the original agent in this class of drugs. Meta-analyses of patients with mild-to-moderately active UC comparing 5-ASA to placebo showed 5-ASA to be significantly superior to placebo. However, about two-thirds of patients treated with 5-ASA fail to enter clinical remission. It is therefore most important to identify strategies to accelerate and maximise the therapeutic effects of 5-ASA. Therapeutic intervention against NFκB activation is a useful strategy for treatment of UC. The 4-alkanoylaminobenzamide PM0503 inhibits the breakdown of the NFκB inhibitor IκBβ, and SASP/5-ASA inhibits the breakdown of IκBα. This elicited a hypothesis of a possible synergistic action and converging effect on NFκB signalling. In the present study, we investigated the effect of combining SASP/5-ASA with PM0503 in experimental colitis.


SASP and PM0503 alone or in combination were administered for 5 days to Balb/c mice with colitis triggered by 5% dextran sulphate sodium (DSS). Blood in the stool, stool consistency and body weight loss were evaluated daily on a 0–4 point scale. The disease activity index (DAI) was calculated by summarising the total score of these three parameters.


Addition of 5% DSS in the drinking water for 5 days produced reproducible symptoms of colitis. PM0503 was shown to inhibit DSS induced colitis by reducing mean DAI at day 5 from 6.9 in controls to 1.7 (a 75% decrease). Mean DAI recorded with SASP treatment at optimal doses in the same series of experiments was 4.4 (a 36% decrease). Furthermore, and most important, lower doses of PM0503 acted synergistically with SASP in ameliorating DSS-induced disease severity. The combination of PM0503 and SASP using suboptimal doses having minimal beneficial effects as monotherapies, showed more than 50% disease inhibition at day 5. In addition, no toxicity was observed with PM0503 alone or in combination with SASP.


Our findings offer a preclinical rationale for simultaneous coadministration of PM0503 and a 5-ASA agent such as SASP or 5-ASA as first-line treatment for patients with UC.