In patients with Crohn disease, greater clinical and endoscopic improvements at week 12 were conferred by all three dose regimens of guselkumab (a selective p19 interleukin-23 antagonist) when compared with placebo, along with a favorable safety profile.

• In a phase 2 double-blind, placebo-controlled study (GALAXI-1), patients were randomized 1:1:1:1:1 to: intravenous guselkumab 200 mg, 600 mg, or 1,200 mg at weeks 0, 4, 8; intravenous ustekinumab ∼6 mg/kg at week 0 and 90 mg subcutaneously at week 8; or placebo.

• Participants were 309 patients, of whom nearly 50% had disease refractory to prior biologic therapy.

• Compared to placebo, significantly greater decreases from baseline in Crohn’s Disease Activity Index and significantly greater proportions of patients had clinical remission in each guselkumab group at week 12.

• At week 12, the proportions of patients who achieved clinical response, Patient Reported Outcomes-2 remission, clinical-biomarker response, and endoscopic response were greater with guselkumab treatment than placebo.

• Ustekinumab was also found to be efficacious than placebo.

• Across treatment groups, the observed safety event rates were generally similar.