Intensification with Intravenous Ustekinumab in Refractory Crohn's Disease

Background: The rates of clinical and biochemical responses in Crohn's disease (CD) patients treated with intravenous (IV) ustekinumab (UST) intensification are scarcely described. Methods: Patients with diagnosis of CD who were under intensified IV ustekinumab treatment (130 mg every 4 weeks) were retrospectively included, evaluating the clinical and biochemical response 12 weeks after the change in treatment regimen (switch from SC to IV), as well as the serum levels of the drug. Results: Twenty-seven patients, all of whom had transitioned to intensified intravenous ustekinumab treatment due to a secondary loss of response to the drug, were included in the retrospective analysis. At the baseline visit, prior to changing IV UST, differences in levels were observed between intensified and non-intensified patients (7216 vs. 2842 ng/mL, p = 0.00005). However, no significant differences were found between these two groups 12 weeks after IV intensification (7949 vs. 7937 ng/mL; p = 0.99). In patients with previous intensified UST SC, a decrease in fecal calprotectin was observed 12 weeks after starting IV intensification, going from a mean of 1463 ug/g to 751 ug/g, although the differences were not significant (p = 0.14). Conclusion: In our experience, intensifying treatment with IV UST leads to clinical and biochemical improvements in CD patients with a secondary loss of response to SC maintenance with this drug, and an increase in drug levels was observed 12 weeks after IV UST intensification.