Safety and pharmacodynamics of a novel recombinant botulinum toxin E (rBoNT-E): Results of a phase 1 study in healthy male subjects compared with abobotulinumtoxinA (Dysport®).

Naturally occurring botulinum toxin (BoNT) serotypes have different pharmacological features of therapeutic and aesthetic interest. This phase 1, double-blind, placebo-controlled study (EudraCT: 2016-002609-20) assessed safety, tolerability and pharmacodynamics (PD) of the first recombinant BoNT serotype E (rBoNT-E) versus abobotulinumtoxinA (Dysport®), administered to extensor digitorum brevis (EDB) of healthy males. Subjects were randomised 3:1 (n = 28) to single ascending rBoNT-E (0.04-3.6 ng) doses or placebo. A further 24 subjects received abobotulinumtoxinA (20, 40, or 70 U) or placebo. PD were assessed using compound muscle action potential (CMAP) amplitude. Demographics were similar between groups. All rBoNT-E doses were well tolerated (no severe treatment-emergent adverse events [TEAEs], serious adverse events, or treatment-related toxicities). Most TEAEs were mild/moderate and treatment-unrelated. rBoNT-E had a faster onset of action (days 1-2 post-injection), greater peak effect (>90% CMAP inhibition), and shorter duration of effect at highest tested doses versus abobotulinumtoxinA (onset of action ≤7 days post-injection; 70% maximal CMAP inhibition). rBoNT-E duration of effect was 2-7 weeks versus >26 weeks for abobotulinumtoxinA. Dose-dependent effects were observed for magnitude and duration of EDB CMAP inhibition, plateauing at 0.9 and 3.6 ng. rBoNT-E demonstrated a good safety profile and a PD profile that may address unmet therapeutic and aesthetic patient needs.