Body Mass Index Does Not Impact Clinical Efficacy of Ustekinumab in Crohn’s Disease: A Post Hoc Analysis of the IM-UNITI Trial

BACKGROUND: This post hoc analysis aimed to evaluate the impact of BMI on the efficacy of ustekinumab in the IM-UNITI study. METHODS: The relationship between body mass index (BMI) and efficacy of ustekinumab was evaluated using data from a 44-week maintenance study of ustekinumab in Crohn's disease (IM-UNITI, NCT01369355, YODA #2019-4105). The primary endpoints of interest were clinical remission (CR), defined as Crohn's disease activity index <150 and corticosteroid-free CR at week 44. Patients were stratified into the following subgroups according to their BMI at study entry: underweight <18.5 kg/m2, normal 18.5 to 25 kg/m2, overweight 25 to <30 kg/m2, and obese ≥30 kg/m2. The χ 2 test of linear trend was conducted for comparisons of frequencies between the 3 cohorts. Multivariate regression analyses evaluated possible association between BMI and efficacy outcomes of CR and corticosteroid-free CR, with adjustment for variables found significant on univariate analyses. Results are presented as odds ratios with 95% confidence intervals. Data were analyzed using Stata/IC 15. RESULTS: A total of 254 patients treated with ustekinumab were included in this analysis. At week 44 of IM-UNITI, rates of CR did not differ among those whose BMI was underweight (67.9%%; 19 of 28 patients), normal (51.3%; 60 of 117), overweight (45.1%; 32 of 71), or obese (55.3%; 21 of 38; P = 0.89). Multivariate logistic analysis did not find BMI to be a significant predictor of CR when adjusted for covariates. Ustekinumab drug level at week 44 was significantly lower in obese patients (median level 2.98 mcg/mL; interquartile range [IQR], 2.86) compared with patients who were overweight (4.84 mcg/mL; IQR, 3.51; P = 0.021) or had underweight or normal BMI (4.43 mcg/m;, IQR, 2.82; P = 0.014). CONCLUSIONS: Although BMI impacts ustekinumab drug levels, there was no impact of BMI on clinical efficacy. Further studies of the pharmacodynamic effects of ustekinumab in patients with high BMI are needed.