Abstract:Objective To evaluate the efficacy of vedolizumab（VDZ）in the treatment of ulcerative colitis（UC）and explore its safety. Methods A retrospective analysis was performed on the clinical data of UC patients treated with VDZ in the Affiliated Huai'an Hospital of Xuzhou Medical University from December 2020 to December 2024. The activity degree and endoscopic severity of UC disease were evaluated using the Modified Mayo Score（MMS）and the Ulcerative Colitis Endoscopic Index of Severity （UCEIS），respectively. Inflammatory markers ［white blood cell（WBC），lymphocyte（LYM），C-reactive protein（CRP），erythrocyte sedimentation rate（ESR），fecal calprotectin（Fc）］and nutritional indicators［body mass index（BMI），albumin（ALB）］were compared between pre-and post-treatment.The patients were divided into the VDZ first-line treatment group and the VDZ second-line treatment group based on whether biological agents were used in their previous treatment of UC，to evaluate the differences in the efficacy of VDZ between the two groups，and the adverse events were recorded. Results A total of 54 UC patients were finally included，with males accounting for 40.74%，the age being（48.85 ± 16.75）years，and the disease duration being 46.00（25.50，70.25）months. At 14th week，the clinical response rate was 51.85% and clinical remission rate was 20.37%. At 30th week，the clinical response rate，clinical remission rate，and endoscopic remission rate reached 66.67%，46.30%，and 27.78%，respectively. At 30th week，compared with the second-line group（n=26）, the first-line VDZ treatment group （n=28）exhibited significantly higher clinical response（82.14% vs 50.00%，χ2=6.268，P=0.012）and clinical remission rate（71.43% vs 19.23%，χ2=14.774，P=0.001）. Compared with baseline values，nutritional indicators significantly increased and inflammatory markers significantly decreased at 30th week（P<0.01）. The incidence of adverse events was 3.70%（2/54）. Conclusion VDZ demonstrates favorable efficacy in both induction and maintenance therapy for UC，significantly improving nutritional status，suppressing inflammation，and exhibiting a high safety profile. Among patients receiving biological agents for the first time，choosing VDZ may yield better effects.