Mirikizumab effectiveness in a pregnant woman with acute severe ulcerative colitis: a case report

Acute severe ulcerative colitis is a potentially life-threatening condition that requires hospitalization with early and aggressive intervention to prevent complications. Mirikizumab (an anti-IL-23 monoclonal antibody) is recommended for the treatment of adult patients with moderate-to-severe ulcerative colitis. Currently, there is lack of evidence supporting its use in acute severe colitis, and no evidence has been produced on the use of this medication in pregnant women. A 30-year-old pregnant woman, with a 4-year history of corticosteroid-refractory pancolitis, who had failure to respond to multiple biological therapies, including infliximab, adalimumab, and vedolizumab, presented with acute severe ulcerative colitis and suspected threatened preterm rupture of membranes at 18 weeks' gestation. After administering five days of intravenous corticosteroids, the patient showed an unfavorable clinical and endoscopic response. Given the corticosteroid-refractory ASUC and the significant obstetric and neonatal risks associated with colectomy, Mirikizumab was initiated as a rescue therapy. Remarkably, within one day of receiving the first dose, the patient exhibited significant clinical improvement. One month after Mirikizumab initiation, the patient maintained clinical remission with improved markers. At 35 weeks and 4 days of gestation, the patient underwent an urgent cesarean section, delivering a preterm female infant. This is the first reported case regarding the efficacy and safety of Mirikizumab as a rescue therapy in a pregnant woman with severe acute ulcerative colitis. Further research is needed to confirm its efficacy in ASUC and the safety of this drug during pregnancy.