P1109 Impact of concomitant mesalazine administration on the efficacy and safety of advanced therapies in ulcerative colitis: a meta-analysis over the induction and maintenance phases

Abstract Background Mesalazine (msz) is commonly used alongside advanced therapies in ulcerative colitis (UC), but its precise effects on efficacy and safety are not fully defined. This meta-analysis indirectly evaluates the impact of concomitant msz use on clinical and endoscopic outcomes and safety profiles in adults with moderate-to-severe UC treated with approved biological agents and small molecules. Methods A meta-analysis of RCTs including approved biological agents (Adalimumab, Infliximab, Golimumab, Mirikizumab, Guselkumab, Ozanimod, Etrasimod, Ustekinumab) and small molecules (Tofacitinib, Upadacitinib) in UC patients reporting concomitant msz use was conducted through a search of four databases. Available data on clinical remission, endoscopic remission, mucosal healing and adverse events were extracted. Msz co-therapy prevalence was categorized using the median concomitant use across datasets as the baseline threshold. Studies were stratified into ‘High’ and ‘Low’ prevalence groups based on this median. Pooled proportions for each outcome and subgroup were estimated, with between-group differences tested by two-tailed z-tests. Separate analyses were performed for induction and maintenance phases, including only approved UC treatment doses. Meta-regression assessed correlations between concomitant mesalazine prevalence and treatment outcomes. Results 32 Phase II and III RCTs were included. No statistically significant differences were shown during the induction phase (Table1). In the maintenance phase, the subgroup with a higher prevalence of msz use showed significantly greater mucosal healing than the low-prevalence group (45.0%[95%CI,32.0%–58.0%] vs. 29.0%[95%CI,21.0%–39.0%]), with a borderline positive correlation in meta-regression (r = 0.503,p=0.067) (Figure1). Conversely, infection rates were significantly higher among patients with higher msz prevalence during maintenance therapy (23.0% [95%CI,0.9%–47.0%] vs. 0.1%[95%CI,0.0%–12.0%]), supported by a significant meta-regression correlation (r = 0.396,p=0.015). No difference was found in serious infection rates between the high and low prevalence groups (p > 0.05). No other efficacy nor safety outcomes showed significant differences between groups. Conclusion The concomitant use of msz and advanced therapies is associated with improved mucosal healing during maintenance therapy for UC, suggesting a potential synergistic effect in the long term. Future prospective studies incorporating histologic outcomes are warranted to elucidate the mechanistic contribution of msz in combination regimens. Conflict of interest: Rodríguez-Lago, Iago: Financial support for traveling and educational activities from or has served as an advisory board member for Abbvie, Adacyte, Alfasigma, Biogen, Chiesi, Faes Farma, Ferring, Fresenius Kabi, Galapagos, Johnson & Johnson, Eli Lilly, Mirum Pharmaceuticals, Merck, Pfizer, Roche, Takeda, and Tillotts Pharma. Research support from AbbVie. Supported by a research grant from Gobierno Vasco-Eusko Jaurlaritza (Grant No 2020111061 and 2023222006). D’Amico, Ferdinando: Grant: ECCO fellowship grant 2020 ECCO grant 2021 Personal Fees: F D’Amico has served as a speaker for Abbvie, Alfasigma, Ferring, Lilly, Sandoz, Janssen, Fresenius Kabi, Galapagos, Giuliani, MSD, Pfizer, Takeda, Tillotts, and Omega Pharma he also served as an advisory board member for Abbvie, AnaptysBio, Ferring, Fresenius Kabi, Galapagos, Janssen, Lilly, MSD, Takeda, and Nestlè. Bamias, Giorgos: Grants: Grants from Takeda, AbbVie, Mylan/Viatris/Biocon, Genesis Pharma, Ferring, Vianex, and Aenorasis Consulting Fees and Speaker Honoraria: AbbVie, Adacyte Therapeutics, Amgen, Bristol Myers Squibb, Faran, Ferring, Galenica, Genesis Pharma, J&ampJ, Lilly, MSD, Mylan/Viatris/Biocon, Pfizer, Shattuck Labs, Takeda, Vianex Mrs. Miranda Azpiazu, Patricia: Employed at Faes Farma S.A Barreiro-de Acosta, Manuel: MBA has been speaker, consultant and advisory member for or has received research funding from MSD, AbbVie, Janssen, Kern Pharma, Celltrion, Takeda, Alphasigma, Lilly, Pfizer, Sandoz, Biocon, Abivax, Fresenius, Faes Farma, Ferring, Tillots, Chiesi, Adacyte, Diasorin, Oncostellae and SunRock.