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

Abstract

Abstract Background 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. Methods 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. Results 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. Conclusion 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.