Use of MM-SES-CD Endoscopic Improvement Thresholds Enhances Effect Size Differentiation between Adalimumab vs. Placebo: A Post-hoc Analysis of the EXTEND Trial.

Introduction: The Modified Multiplier of the SES-CD (MM-SES-CD) refines the assessment of endoscopic Crohn's Disease (CD) severity by differentially weighting parameters in the original SES-CD. A threshold of <22.5 for MM-SES-CD suggests endoscopic remission and correlates with a low risk of long-term disease progression. This study examines whether MM-SES-CD-defined endoscopic remission (ER) and response criteria are more sensitive to treatment effects compared to conventional SES-CD definitions.

Methods: This post-hoc analysis of the EXTEND trial compared various SES-CD and MM-SES-CD definitions of ER and endoscopic response in CD patients treated with adalimumab or placebo. The study included participants with moderate-severe CD and a baseline MM-SES-CD score ≥22.5. The primary outcome of ER, defined as MM-SES-CD <22.5, was evaluated at weeks 12 and 52. AUC analyses compared thresholds for predicting week 52 ER.

Results: Of the 100 participants (77.5% of the EXTEND population), 51 received adalimumab and 49 placebo. At week 12, 62% achieved MM-SES-CD ≥20% reduction from baseline, compared to 39% with SES-CD ≥50% reduction. At week 52, 56.9% of adalimumab-treated participants achieved MM-SES-CD <22.5, compared to 10.2% in the placebo group. MM-SES-CD ≥20% reduction at week 12 better predicted week 52 ER than SES-CD ≥50% reduction (AUC: 0.73 vs. 0.62, p=0.002).

Conclusion: MM-SES-CD definitions improved discrimination between treatment and placebo and offered superior predictive accuracy for week 52 ER. Its use may enhance trial efficiency and better predict long-term disease outcomes.