A Cochrane review included 4 studies with 606 subjects. Vedolizumab was significantly superior to placebo for induction of remission, clinical response, and endoscopic remission and prevention of relapse. After 4 to 6 weeks of therapy 77% (293/382) of vedolizumab patients failed to enter clinical remission compared to 92% (205/224) of placebo patients (RR 0.86, 95% CI 0.80 to 0.91; 4 studies 606 patients). After 6 weeks of therapy 48% of vedolizumab patients failed to have a clinical response compared to 72% of placebo patients (RR 0.68, 95% CI 0.59 to 0.78; 3 studies 601 patients). After 4 to 6 weeks of therapy 68% of vedolizumab patients failed to enter endoscopic remission compared to 81% of placebo patients (RR 0.82, 95% CI 0.75 to 0.91; 3 studies, 583 patients). After 52 weeks of therapy, 54% of vedolizumab patients had a clinical relapse compared to 84% of placebo patients (RR 0.67, 95% CI 0.59 to 0.77; 1 study, 373 patients). One small study (28 patients) found no statistically significant difference in endoscopic response (RR 1.00, 95% CI 0.62 to 1.61).
There was no statistically significant difference between vedolizumab and placebo in terms of the risk of any adverse event (RR 0.99, 95% CI 0.93 to 1.07), or serious adverse events (RR 1.01, 95% CI 0.72 to 1.42). There was a statistically significant difference in withdrawals due to adverse events. Six per cent of vedolizumab patients withdrew due to an adverse event compared to 11% of placebo patients (RR 0.55, 95% CI 0.35 to 0.87; 2 studies, 941 patients). Adverse events commonly reported across the studies included: worsening ulcerative colitis, headache, nasopharyngitis, upper respiratory tract infection, nausea, and abdominal pain.