Randomised clinical trial: a placebo‐controlled study of subcutaneous or intradermal NEXVAX2, an investigational immunomodulatory peptide therapy for coeliac disease

Background Nexvax2 contains three gluten-derived peptides, intended to tolerize coeliac disease patients to gluten. Sequences cover six epitopes that trigger immune activation in human leucocyte antigen-DQ2.5-positive patients, most notably after an initial dose. Patients experience gastrointestinal symptoms with increases in serum interleukin-2. Consistent with Nexvax2's induction of non-responsiveness, reactivity disappears after repeated doses, or is avoided with gradual dose escalation. Early clinical trials used intradermal dosing, but pharmacokinetics and rapid onset of effect suggest that subcutaneous delivery may also be effective. Aims To document the relative bioavailability of Nevax2 peptides after subcutaneous and intradermal dosing, and the tolerability and ability of subcutaneous dosing to induce non-responsiveness to Nexvax2 peptides. Methods A randomised, double-blind, placebo-controlled study was conducted to assess plasma pharmacokinetics after subcutaneous and intradermal Nexvax2 dosing in HLA DQ2.5-positive patients, who had symptoms after an oral gluten challenge. Randomisation was to semi-weekly Nexvax2 (n = 12) or placebo (n = 2) injections, over a 5-week subcutaneous dose escalation and 2-week maintenance period, the latter with four doses of 900 mu g, two subcutaneous and two intradermal. Post-dose circulating peptide and interleukin-2 levels were assessed. Investigators recorded adverse events experienced by patients. Results Subcutaneous dosing resulted in slightly greater exposure. Interleukin-2 responses were seen with the gluten challenge but not after subcutaneous or intradermal dosing of 900 mu g. Adverse events were generally mild and self-limited. Conclusions Subcutaneous and intradermal dosing of Nexvax2 yield similar bioavailability of constituent peptides; subcutaneous dose escalation avoids an immune response to dominant gluten epitopes.