Background: Human transglutaminase 2 (TG2) is key in celiac disease (CeD) pathogenesis and target of the oral TG2 inhibitor ZED1227. In the phase2a CEC-003/CEL study, ZED1227 improved intestinal histology during gluten-challenge. However, despite a gluten-free diet (GFD) up to half of patients continue to experience symptoms and persistent villous atrophy, highlighting need for additional treatments.
Aim: To evaluate the efficacy and safety of ZED1227 in CeD patients with residual symptoms and villous atrophy despite adherence to a GFD.
Methods: CEC-004/CEL was a double-blind, randomized, placebo-controlled phase2b trial. Adults with CeD on a GFD for ≥1 year and ≥1 moderate-to-severe gastrointestinal symptom underwent a 5-week placebo run-in. Patients with a villous height-to-crypt depth ratio (VH:CrD) ≤2.5 were randomized (1:1:1:1) to placebo 3x daily (TID), ZED1227 10mg TID, ZED1227 25mg TID, or ZED1227 50mg once daily (QD) for 12 weeks. No gluten challenge was performed. The primary endpoint was patients achieving both ≥0.4 improvement in VH:CrD and ≥15% improvement in either non-stool gastrointestinal symptoms or diarrhea severity on the Celiac Disease Symptom Diary (CDSD).
Results: Among 397 randomized patients, 92.7% completed treatment. The primary endpoint was achieved by 27.1%, 16.9%, 25.3%, and 19.3% of patients receiving ZED1227 10mg TID, 25mg TID, 50mg QD, and placebo, respectively, with no significant differences versus placebo. Mean VH:CrD changes were 0.21, 0.17, and 0.26 with ZED1227 versus 0.12 with placebo; only 50mg QD was significantly superior to placebo (p<0.05). CDSD GI total severity scores improved significantly within all groups, without significant between-group differences. Safety profiles were comparable across groups, with no treatment-related serious adverse events.
Conclusions: Although the primary endpoint was not met, ZED1227 50mg QD produced a significant histologic benefit versus placebo and showed a favorable safety profile, consistent with previous findings. Placebo-group improvements highlight challenges evaluating therapies in partially treated CeD without gluten exposure.