Effects of Ustekinumab on Histologic Disease Activity in Patients With Crohn's Disease

BACKGROUND & AIMS: Although ustekinumab is an effective therapy for moderate to severe Crohn's disease (CD), its effects on the microscopic manifestations of CD are unknown. METHODS: We evaluated the effects of ustekinumab on histologic CD activity in an analysis of data from 251 participants in phase 3 induction and maintenance studies. Two endoscopic biopsy samples were collected at weeks 0, 8, and 44 from the ileum, splenic flexure, and rectum (18 biopsy samples from each patient). Histologic activity was assessed based on global histology activity scores (GHASs). RESULTS: At week 8, the mean GHAS was significantly reduced after ustekinumab induction treatment (from 10.4 +/- 7.0 to 7.1 +/- 5.9; P < .001) but not in patients who received placebo (from 9.2 +/- 6.4 to 7.8 +/- 6.2). At week 44 in the randomized maintenance therapy population, the mean GHAS remained reduced from week 8 in patients who received subcutaneous ustekinumab (90 mg every 8 weeks; from 7.4 +/- 7.7 to 6.1 +/- 4.7) but not every 12 weeks (from 5.3 +/- 3.9 to 8.7 +/- 4.1) or placebo (from 9.2 +/- 3.8 to 10.9 +/- 7.1). In the pooled (randomized and nonrandomized) maintenance therapy population, histologic improvement continued in patients given ustekinumab every 8 weeks (from 7.1 +/- 6.2 to 5.2 +/- 4.2; P < .0001) but not in those given ustekinumab every 12 weeks (from 6.1 +/- 5.7 to 7.2 +/- 5.1) or placebo (from 8.2 +/- 4.2 to 8.9 +/- 6.8). A significantly greater proportion of patients achieved histologic response (>= 50% decrease in GHAS from baseline) at week 44 if they received ustekinumab every 8 weeks (50% in the randomized maintenance population and 54% in the pooled maintenance population) compared with every 12 weeks (17% and 39% in the randomized and pooled populations, respectively) or placebo (0% and 22% in the randomized and pooled populations, respectively) (P = .0137 for every 8 weeks vs placebo and P = .3529 for every 12 weeks vs placebo in the randomized population; P = .0168 for every 8 weeks vs placebo and P = .3069 for every 12 weeks vs placebo in the pooled population). Regional and overall mean GHASs correlated with the simple endoscopic score for CD (r = .6255, P < .0001). Multivariate analysis found an association between histologic improvement and endoscopic or histologic burden at baseline. CONCLUSIONS: In an analysis of data from participants in phase 3 induction and maintenance trials, we found histologic improvement in a greater proportion of patients given ustekinumab vs placebo. The largest improvements occurred in patients who received ustekinumab maintenance therapy every 8 weeks.