Probiotic Treatment of Ulcerative Colitis with Trichuris suis ova: A Randomized, Double-blinded, Placebo-controlled Clinical Trial (the PROCTO Trial).

Background and aims: To demonstrate that administration of 7500 Trichuris suis ova every second week over 24 weeks would reduce the intestinal inflammation in moderate ulcerative colitis.

Methods: A single-centre, randomized, double-blinded, placebo-controlled, phase 2b clinical trial of 7500 Trichuris suis ova every two weeks for 24 weeks compared to placebo in moderate activity of ulcerative colitis (Mayo score 6-10) were performed. Primary outcome: Clinical remission. Secondary outcomes: Clinical response at 24 weeks, complete corticosteroid-free clinical remission, endoscopic remission, symptomatic remission at 12 and 24 weeks and partial Mayo score over time.

Results: 119 patients were randomized to Trichuris suis ova (n=60) and placebo (n=59). At week 24, clinical remission was achieved in 30% of Trichuris suis ova-treated vs. 34% of placebo-treated (RR=0.89; CI:0.52-1.50; p=0.80, ITT). No difference was found in clinical response in any of the clinical response subgroups. However, in patients who did not need treatment with corticosteroids during the trial, a temporary effect of TSO was seen in the analysis of symptomatic remission of week 12 (p=0.01), and the partial Mayo score at week 14 and week 18 (p<0.05 and p=0.02).

Conclusions: Compared to placebo, Trichuris suis ova was not superior in achieving clinical remission at week 24 in ulcerative colitis or in achieving clinical Mayo score reduction, complete corticosteroid-free clinical remission or endoscopic remission. However, Trichuris suis ova treatment induced symptomatic temporary remission at week 12.