SUMMARY
Background
Gluten-free diet (GFD) is the only management available for celiac disease (CeD), a permanent immune intolerance to gluten. Nexvax2® is the first therapeutic vaccine designed to treat CeD. The adjuvant-free formulation of peptides is intended to engage and render gluten-specific CD4+ T cells unresponsive to further antigenic stimulation. We have assessed safety and pharmacodynamics of Nexvax2® in patients with CeD on GFD.
Methods
In two randomized, double-blind, placebo-controlled, phase 1 studies at 12 community sites in Australia, New Zealand and the United States, we screened for HLA-DQ2·5+ CeD patients (aged 18–70 years) on GFD. The screening and post-treatment periods included either a crossover, placebo-controlled, oral gluten challenge (OGC) to mobilize and assess T cells responsive to Nexvax2 or, for the final cohort in each study, endoscopy and duodenal histology without OGC. Participants and study staff were masked to the gluten content of food provided for each interval of the OGCs. One of two sequences of active and placebo challenges was assigned (1:1) by central randomization using a simple block method. The sequence of challenges was active/placebo then active/placebo, or placebo/active then active/placebo for the OGCs in the screening and post-treatment periods, respectively. Participants with a negative interferon (IFN)-γ release assay (IGRA) to Nexvax2 peptides after the screening OGC, or Marsh score >1 were discontinued before dosing. There was temporal allocation of participants to sequential cohorts assessing multiple fixed intradermal doses of Nexvax2 (60µg, 90µg, or 150µg weekly in the 3-dose study; or 150µg, or 300µg two-times weekly in the 16-dose study) in 0.1 mL 0.9% sodium chloride. A maximum tolerated dose (MTD) was administered in the final biopsy cohort in each study. Participants within each cohort were assigned to receive Nexvax2 or placebo by central randomization (2:1, respectively) using simple block method in SAS software Version 9·2. Participants, investigators, and study staff were masked to the treatment assignment, except for the study pharmacist. The primary endpoint was the number and percentage of adverse events in the treatment period. Other safety outcomes included duodenal histology, gastrointestinal symptoms, plasma cytokines, and immune cell frequencies. The main pharmacodynamic endpoint was IGRA to Nexvax2 peptides. All participants who received Nexvax2 or placebo, the safety population, were included in an intention to treat analysis for the primary endpoint. Additional post hoc analyses were also performed. Both trials were completed and closed before data analysis. Trials were registered with Australian New Zealand Clinical Trials Registry, numbers ACTRN12612000355875 and ACTRN12613001331729.
Findings
Participants were screened from November 28, 2012 to August 14, 2014, and August 3, 2012 to September 10, 2013, for the 3-dose and 16-dose studies respectively. Across both studies, 136 (80%) of 169 volunteers met initial eligibility crite...
