Profile of Patients Initiating Mirikizumab for Ulcerative Colitis in the United States

Abstract BACKGROUND Mirikizumab (miri), an anti-interleukin (IL)-23p19 monoclonal antibody approved for ulcerative colitis (UC) and Crohn’s disease, demonstrated sustained efficacy and safety in patients with moderately to severely active UC in LUCENT clinical trials.1,2 However, real-world data on utilization of miri in the United States (US) are limited. METHODS This retrospective observational study used administrative claims from HealthVerity, a database that merges and deduplicates pharmacy and medical claims and enrollment information from closed claims data suppliers participating in the HealthVerity Marketplace. We described baseline demographic, clinical characteristics, and treatment history of UC patients in the US initiating miri and at 3 months follow-up. Adults diagnosed with UC who initiated miri between October 26, 2023 (post-US Food and Drug Administration approval) and July 2025 with at least 3-month follow-up available were included. The index date was defined as the date of the first medical or pharmacy claim for intravenous (IV) miri. Baseline was defined as 12 months prior to the index date (pre-index period), and outcomes were assessed 3 months after baseline. Descriptive statistics were used to report patient characteristics and outcomes. RESULTS A total of 233 patients initiating IV miri for UC were identified, of whom 142 (60.9%) had 3 months of follow-up and were included in this analysis. Patients had a mean (standard deviation SD) age of 41.8(14.6) years, 51.4% were female. Most commonly reported baseline comorbidities were anemia (26.1%), abdominal pain (20.4%), hypertension (18.3%). Baseline immunomodulator use was reported in 10 (7.0%) patients, 5-aminosalicylate use in 64 (45.1%), oral corticosteroid use in 96 (67.6%, Figure 1A). Baseline advanced UC therapy use was observed in 104 (73.2%) patients: 77 (54.2%) received one advanced therapy; 23 (16.2%) received two; and 4 (2.8%) received three or more advanced therapies. Within baseline advanced therapies, 84 (59.2%) patients used biologics, 33 (23.2%) used Janus Kinase Inhibitors (JAKi), and 4 (2.8%) used Sphingosine-1-Phosphate (S1P) receptor modulators. The most recent baseline advanced therapy before miri was approximately equally distributed between anti-integrin, JAKi, and IL12-23 (Figure 1B). Oral corticosteroid prescriptions declined from 67.6% at baseline to 28.2% in the 3 months after initiation. CONCLUSION Most patients initiating mirikizumab were previously exposed to biologics and failed one prior advanced therapy. Even so, more than 25% of the early initiators of mirikizumab included patients with no advanced therapy at baseline. Further research will evaluate follow-up treatment patterns with mirikizumab use.